CN1420224A - Buttonhole sewing machine - Google Patents

Abstract

A buttonhole sewing machine (10), comprising: a cloth feed table (13), a hook seat (31), a needle plate (32) with a needle hole (32b), a rotating mechanism for rotating the hook seat (31) ( 15). A bobbin thread cutting device (30) for cutting the bobbin thread after sewing is finished. The bobbin thread holding mechanism is composed of the bobbin thread guiding surface (32f) of the needle plate (32) and the bobbin thread presser foot (27). . An opening (32c) opening to one side from the needle hole (32b) is provided in the needle plate (32). And it is equipped with a guide mechanism composed of a rotating mechanism (15) and a cloth feeding table (13) that draw out the lower thread from the opening (32c) and guide it to the lower thread holding mechanism to hold it after sewing. Therefore, on the buttonhole sewing machine, the end of the bobbin thread can be held and cut as short as possible, and can be reliably sewn into the next buttonhole stitch.

Description

Buttonhole Sewing Machine

technical field

The present invention relates to a buttonhole sewing machine for forming buttonhole stitches by chain sewing, and more particularly to the cutting and holding of the lower thread.

Background technique

Conventionally, a buttonhole sewing machine is known in which a buttonhole is formed by starting operation of the sewing machine, and a buttonhole stitch is formed around the buttonhole by chain sewing. In such a buttonhole sewing machine, the needle on which the upper thread is threaded moves up and down and swings, while the hook on which the lower thread is threaded moves, and the stitches are formed around the buttonhole by the coordinated action of both.

In the buttonhole sewing machine, as described in Japanese Patent Application Publication No. 9-225166, after the overlock stitch is formed, the bobbin thread (hook thread) connected between the hook and the processed fabric is cut off and the side of the hook is cut off. The thread end is kept until the next seaming mechanism. In the buttonhole sewing machine described in the above bulletin, guide grooves are formed on the needle plate for conveying the processed cloth on the needle plate in a prescribed direction after the buttonhole stitches are formed, thereby transferring the processed cloth, That is, the end of the buttonhole stitch guides the bottom thread connected to the hook under the needle plate into the above-mentioned guide groove, and in the state where the bottom thread is held by the holding part provided at the rear end of the needle plate, and close to the lock The position at the end of the buttonhole stitch cuts off the bottom thread. The end of thread on the side of the rotary hook held by the above-mentioned holding portion is sewn into the buttonhole stitch as the cloth is conveyed due to the buttonhole when the next sewing starts.

However, the above-mentioned bottom line cutting and maintaining mechanism has the following problems:

(1) In order to guide the lower thread into the guide groove by the movement of the processed material on the needle plate, it is necessary to feed the processed material a considerable distance and pull the lower thread from the hook for a long time before cutting the lower thread. In this way, the bottom thread is pulled out for a long time. In addition to wasting the bottom thread, the thread end that must be sewn into the next buttonhole stitch is also very long, or the stitches with ugly appearance are formed, or the thread ends are exposed from the buttonhole stitch forming part, thereby reduce its commodity value.

(2) The bobbin thread held by the above-mentioned holding portion is gradually sewn into the buttonhole stitch as the next buttonhole is performed, and immediately comes out from the holding portion. The bobbin thread that comes out from the holding part is in a free state that is opened from the top of the guide groove relative to the guide groove, and it is easy to be sewn in in a state where it is released from the buttonhole stitch forming part, and forms a lock when it comes out. After buttonhole stitching, it is necessary to cut the exposed thread ends by hand.

In addition, in the eyelet sewing machine, since the needle and the needle plate rotate synchronously at the eyelet part, once the thread end that must be sewn is very long as described in (1), the thread end reaches the rotating part, And when changing the direction of the needle plate relative to the cloth while rotating, it is easy to come out from the stitches.

(3) The position of the guide groove on the needle plate, which is set at the needle drop position (inner needle) on the side of the buttonhole and the needle drop position far from the buttonhole in order to reliably guide the thread end and sew it into the buttonhole stitch. (outer needle) position.

However, in buttonhole sewing machines, as is well known, there is a practice of threading a filler thread between the upper thread and the lower thread. A filler thread hole for guiding a filler thread into a buttonhole stitch and formed on a needle plate is formed between an inner needle and an outer needle. That is, the filling thread hole is formed at almost the same position as the guide groove of the above announcement, so such a needle plate with the guide groove cannot be used for sewing the overlock of the filling thread.

In addition, a bobbin thread cutting device for a buttonhole sewing machine is well known and described in JP-A-2001-232086. The bobbin thread cutting device described in this bulletin is arranged on a cloth feeding table for conveying processed cloth. It is a structure in which the lower thread is cut right below the end of the buttonhole stitch of the processed material after the buttonhole stitch is completed and the cloth feed table is sent to the predetermined origin position.

However, since the bobbin thread cutting device is fixed on the cloth feeding table, if the length of the buttonhole stitches changes, it is necessary to adjust or replace the positions of the other parts constituting the bobbin thread cutting device, which is very troublesome. In other words, the slit length has to be specified as a certain length.

The object of the present invention is to reliably sew the next buttonhole stitch even if the length of the cut bobbin thread remaining on the hook is short on a buttonhole sewing machine provided with a bobbin thread cutting and holding device.

In addition, another object is to adapt to various seam lengths without adjusting or replacing parts of the bobbin thread cutting device, and to make the parts common regardless of the presence or absence of filler threads.

Contents of the invention

In order to solve the above-mentioned problems, the invention described in the first aspect of the present invention, as shown in FIGS. And move up and down, and make the needle fall alternately at the outer needle drop position far away from the buttonhole and the inner needle drop position near the buttonhole formed on the processed fabric, and perform the needle bar and device for swinging the needle according to the specified swinging direction On the sewing machine base (base 12), the cloth feeding mechanism (cloth feeding table 13) that transfers the processed cloth to at least one direction perpendicular to the above-mentioned needle swing direction is arranged on the sewing machine base facing the above-mentioned needle bar, and There is a rotary hook seat (31) that cooperates with the above-mentioned needle bar and winds the bobbin thread on the above-mentioned upper thread (left-handed hook 6, right-handed hook 5). The needle plate (32) including the two-point needle holes (32b) at the inner needle entry position and the outer needle entry position, the rotation mechanism (rotation mechanism 15) that rotates the needle bar and the hook seat when locking the buttonhole, and the needle at the buttonhole locking The bobbin thread cutting device (bobbin thread cutting device 30) that cuts the bobbin thread connected to the processing cloth from the rotary hook after the trace is finished, keeps the bobbin thread connected to the bobbin thread before cutting with the bobbin thread cutting device, and after cutting, when the buttonhole is locked next time The bobbin thread holding mechanism that uses the above-mentioned cloth feeding mechanism to transfer the processed cloth and keep the end of the thread to be sewn into the stitch naturally is characterized in that the buttonhole of the buttonhole stitch (W) is formed around the buttonhole (H) On the sewing machine (10), the bobbin thread holding mechanism is provided around the needle plate, and the needle plate is provided with an opening (32c) which is continuously opened to one side from the needle hole, and has the bobbin thread cut off after the buttonhole is finished. Before, the bobbin thread that passes through the needle hole from the rotary hook and is connected to the material to be processed is held by the bobbin thread holding mechanism and drawn out from the opening.

According to the invention according to the first aspect of the present invention, after the buttonhole is completed, the bobbin thread that passes through the needle hole from the hook and is connected to the material to be processed is drawn out and guided by the guide mechanism from the opening of the needle plate, and held at the needle plate. It is installed on the bobbin thread holding mechanism around the needle plate, and in this state, the bobbin thread cutting device cuts the bobbin thread between the hook and the processed fabric.

That is, it is not necessary to send the processed cloth for a considerable distance before cutting the bottom thread in order to guide the bottom thread in the guide groove as described in the above-mentioned Japanese Unexamined Patent Publication No. 9-225166, but only guide the bottom thread from the needle hole to the periphery of the needle plate through the opening. The bottom line keeps the agency, so it doesn't have to be elicited as long as the above announcement.

Therefore, the lower thread connected from the hook to the material to be processed can be cut in an extremely short state by the lower thread cutting device. In short, the thread remaining on the side of the processed fabric can be as short as the distance from the end point of the buttonhole stitch to the needle plate, and is held by the bobbin thread holding mechanism, and the thread remaining on the side of the hook can be shortened to the needle. board distance. Therefore, the end of the thread to be sewn in next time the buttonhole is short, does not look ugly, and can be reliably sewn in.

In addition, waste is reduced due to the small withdrawal of the bobbin thread.

In addition, the phrase "feeds the processed cloth at least in one direction perpendicular to the above-mentioned swinging direction" about the cloth feeding mechanism means that it may be configured to be movable in other directions.

Furthermore, the lower thread holding mechanism may be provided around the needle plate, but it is also possible to specifically modify the setting of the needle plate, or install a plate-shaped member capable of clamping the lower thread on the needle plate.

Or as described in claim 2, also can be made of needle plate and other parts.

That is, according to the buttonhole sewing machine described in the first aspect of the present invention, the invention described in the second aspect of the present invention is characterized in that: the bobbin thread holding mechanism is arranged on the needle plate, and guides the cut bobbin thread end into the lock formed next time. The lower thread guide portion (lower thread guide surface 32f) in the buttonhole stitching and the lower thread presser member (lower thread presser 27) for pressing the lower thread onto the lower thread guide portion are constituted.

According to the invention described in the second aspect of the present invention, since the lower thread is clamped by pressing the lower thread on the lower thread guide part by the lower thread presser member, and is guided by the lower thread guide part when the next buttonhole is locked, it is possible to reliably sew. into the buttonhole stitch. In addition, if the needle plate is made small, and the needle hole at the position where the stitches are formed is close to the bottom thread guide, the thread end can also be kept as hard as possible until it is reliably sewn into the stitches, and will not come out of the stitches.

In addition, since the bobbin thread holding mechanism also serves as a guide member in addition to holding it, the structure of this part can be simplified.

According to the buttonhole sewing machine according to the second aspect of the present invention, the invention according to the third aspect of the present invention is characterized in that the bobbin thread presser member is driven by a common driving mechanism (the upper thread cutting driving mechanism 60) with the bobbin thread cutting mechanism. , and press the lower thread onto the lower thread guide.

According to the invention described in claim 3, since the bobbin thread presser member is driven by the same driving mechanism as the bobbin thread cutting mechanism, the overall structure can be simplified. In addition, since the driving source is the same, there is almost no deviation in the synchronous one-time adjustment of the bottom thread pressing and bottom thread cutting.

The buttonhole sewing machine according to claim 2 or 3 of the present invention, or the invention according to claim 4 , includes: an upper thread cutting device (upper thread cutting device 7 ) that cuts the upper thread after the buttonhole is completed; The upper thread cutting driving device (60) of the upper thread cutting device is characterized in that:

At least one of the lower thread cutting mechanism and the lower thread presser member is driven by the upper thread cutting device.

According to the invention described in claim 3, since at least one of the lower thread cutting mechanism and the lower thread presser member is driven by the upper thread cutting device, the overall structure can be simplified.

The buttonhole sewing machine according to any one of the present inventions 2 to 4, the invention described in the fifth aspect of the present invention is characterized in that it has an adjustable minimum distance between the bobbin thread guide part and the bobbin thread presser member to keep the bobbin thread close The adjustment mechanism (stop bolt 21 and nut 22).

According to the invention described in claim 5 of the present invention, since the minimum distance between the bobbin thread guide and the bobbin thread presser member for keeping the bobbin thread close can be adjusted by the adjusting mechanism, and the holding force can be adjusted to suit the thickness or properties of the bobbin thread being held, Therefore, the bottom thread will not come out at the beginning of sewing due to weak holding force, or the bottom thread will not be cut due to strong holding force on the contrary. In addition, from another point of view, it is also possible to adjust the force when the bobbin thread guide part and the bobbin thread presser part are handed over, and to prevent the impact on the needle plate, which is an important part, when the bobbin thread is held.

According to the buttonhole sewing machine according to any one of the inventions 1 to 5, the invention according to the invention according to the sixth invention is characterized in that the above-mentioned guide mechanism is composed of the above-mentioned rotating mechanism and the above-mentioned cloth feeding mechanism, After the buttonhole, first use the cloth feeding mechanism to transport the processed cloth to the opening of the needle plate, and then use the rotating mechanism to rotate the needle plate together with the hook seat to connect the bobbin thread from the above hook through the needle hole to the processed cloth. Guide the bottom thread holding mechanism along the outer peripheral surface of the needle plate.

According to the invention described in claim 6 of the present invention, since the lower thread passing through the needle hole is first guided to the opening by the feed mechanism, and then the needle plate is rotated by the rotating mechanism, the lower thread is relatively guided along the outer peripheral surface of the needle plate. , and guide it to the bottom line holding mechanism. That is to say, it is not necessary to set up a new mechanism for the guide mechanism but utilize the existing mechanism provided on the buttonhole sewing machine, so compared with setting a dedicated mechanism, it can save cost and space.

In addition, by properly controlling the feeding amount of the cloth feeding mechanism, it is possible to change the drawing-out amount of the bobbin thread. As a result, the length of the bobbin thread remaining on the processing cloth side can be selected, and it can also be changed appropriately to a certain extent, and the degree of freedom is high.

In addition, the cloth feeding and rotating actions can also be used only to guide the bobbin thread. In addition, the operation to start the next buttonhole can also be used. In this case, the operation time for guiding the bobbin thread is not required in terms of time, and the efficiency is high.

According to the buttonhole sewing machine according to any one of the inventions 1 to 6, the invention according to the invention of the invention 7 is characterized in that the bobbin thread holding mechanism is provided at the inner needle drop position and the outer needle drop position in the connecting needle hole. The position between the straight lines of the needle position and the vertical plane perpendicular to the straight line.

According to the invention according to claim 7, the bobbin thread holding mechanism is installed between the straight line connecting the inner needle entry position and the outer needle entry position in the needle hole and coincides with a vertical plane perpendicular to the straight line. , so the bottom thread held by the bottom thread holding mechanism is naturally guided between the inside needle drop position and the outside needle drop position when the buttonhole starts, and is reliably sewn into the stitch.

In the buttonhole sewing machine according to any one of claims 1 to 7, the invention according to claim 8 is characterized in that the bobbin thread holding mechanism is provided below the needle hole.

According to the invention described in claim 8, since the lower thread holding mechanism is provided under the needle hole, it is easy to form a hole for passing the filling thread on the needle plate, and the parts can be used in common regardless of whether the filling thread is required or not. .

In the buttonhole sewing machine according to any one of the inventions 1 to 8, the invention according to the invention of the invention 9 is characterized in that the bobbin thread cutting mechanism is used to feed the bobbin thread after the bobbin thread is held by the bobbin thread holding mechanism. Before the mechanism transfers the processed fabric, the bottom thread is cut off.

According to the invention of claim 9, since the bobbin thread cutting mechanism cuts the bobbin thread connected to the processing cloth from the rotary hook after the bobbin thread holding mechanism holds the bobbin thread holding mechanism and before the processing cloth is transferred by the cloth feeding mechanism, it does not Can draw the long bottom thread that is connected with processing cloth from rotary hook as described in above-mentioned Japanese patent unexamined flat 9-225166 announcement. Thereby, the bobbin thread cutting mechanism cuts off the bobbin thread which is connected with the processed cloth from the rotary hook in a state shortened as much as possible. That is, the thread remaining on the side of the processed fabric is only the distance from the end point of the buttonhole stitch to the needle plate, and is held by the bobbin thread holding mechanism, that is to say, the thread remaining on the side of the hook is shortened to the distance from the needle plate. length. Therefore, the thread that is sewn in the next time the buttonhole is sewn in is short, does not look unsightly, and can be sewn in reliably.

In addition, since the bobbin thread is drawn out less, waste of machine thread is reduced.

In the buttonhole sewing machine according to any one of claims 1 to 9, the invention according to claim 10 is characterized in that the bobbin thread cutting mechanism is provided on the hook base.

According to the invention described in claim 10 of the present invention, since the bobbin thread cutting mechanism is provided on the hook seat, the cutting position is fixed, and the bobbin thread cutting mechanism can be independent of the slit length, so it is not necessary to adjust or replace the parts of the bobbin thread cutting mechanism according to the slit length. etc. It is not limited by the fixed seam length of the buttonhole, and buttonholes of free length can be sewn.

Description of drawings

Fig. 1 is an exemplary view of a buttonhole sewing machine according to the present invention, (a) is an overall perspective view, and (b) is a partial side sectional view of a machine base.

Fig. 2 is a plan view showing the structure of the upper thread cutting drive mechanism.

Fig. 3 is a front plan view of the lower thread cutting device.

Fig. 4 is a side view of the lower thread cutting device of Fig. 3 .

Fig. 5 is a plan view of the bobbin thread cutting device seen from above.

Fig. 6 is a perspective view of a needle plate member.

Fig. 7 is a control program diagram of the buttonhole sewing machine in Fig. 1 .

Fig. 8 is an operation sequence diagram of the lower thread cutting device of Fig. 3 .

FIG. 9 is a continuation diagram of FIG. 8 .

Fig. 10 is a detailed plan view of the bobbin thread cutting device seen from above in Fig. 8(c).

Fig. 11 is a detailed plan view of the bobbin thread cutting device seen from above at the time of Fig. 8(d).

Fig. 12 is a detailed plan view of the bobbin thread cutting device seen from above in Fig. 8(e).

Fig. 13 is a state view of the second stopper pin of the lower thread cutting knife arm of the lower thread cutting device abutting against the hook seat before the lower thread is cut.

In the figure: 5-right-handed hook, 6-left-handed hook, 7-upper thread cutting device (upper thread cutting mechanism), 10-buttonhole sewing machine, 11-needle bar, 12-base part (sewing machine base), 14b -Arm (sewing machine arm), 15-rotation mechanism (rotation device), 18-sewing machine needle (needle), 13-cloth feeding table (cloth feeding mechanism), 20-bottom thread cutter, 21-stop bolt (adjustment mechanism), 22-nut (adjusting mechanism), 24-bottom thread presser foot mounting seat, 26-bottom thread cutter arm, 26d-protruding pin, 27-bottom thread presser foot (bottom thread pressing part), 27a-bottom thread pressing surface, 30 -Lower thread cutting device, 31-hook seat, 32-needle plate, 32c-opening part, 32d-lower corner part, 32e-peripheral part, 32f-lower thread guide surface (lower thread guide part), 60-needle thread cutting drive mechanism, 69-thread cutting drive arm, 86-machine thread cutting action cylinder, 78-upper thread cutter, 81-spindle motor, W-lock buttonhole stitch, H-buttonhole.

Detailed ways

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

A buttonhole sewing machine 10 (hereinafter, simply referred to as the sewing machine 10 ) of the present invention shown in FIG. 1 is an automatically controlled sewing machine that performs buttonhole locking with chain stitches. Sewing machine 10, which can form various buttonhole stitches by selecting patterns. Here, the overlock stitch W is formed around the buttonhole H composed of the drop-shaped round eye portion h1 and the straight line portion h2 shown in FIG. 9( b ), for example. The overlock stitch W is composed of a right side seam w1, a round eye seam w2 around the round eye h1, a left side seam w3, and a straight backtack seam w4.

The sewing machine 10 of Fig. 1 mainly has: a substantially rectangular box-shaped base portion 12, a vertical body portion 14a rising from the rear portion of the base portion 12, and a vertical body portion 14a protruding forward from the vertical body portion 14a. The arm portion 14b is placed on the sewing machine table (not shown) via the lower cover 16 . At the front portion of the arm portion 14b, there is provided a needle bar 11 capable of moving up and down and swinging in the left and right directions (X direction in FIG.

In addition, the sewing machine 10 further includes an operation panel 90 for the operator to perform various settings, and a control device 110 for controlling a series of sewing operations of the sewing machine 10 (see FIG. 7 ).

An upper shaft extending in the front-rear direction is provided in the arm portion 14b (not shown). In addition, a lower shaft extending in the front-rear direction is provided inside the base portion 12 . The upper shaft and the lower shaft are connected by a synchronous belt, and driven by a main shaft motor 81 to rotate synchronously.

The above-mentioned needle bar 11 is connected to the upper shaft through a needle bar vertical driving mechanism and a swing mechanism which are not shown in the arm portion 14b. Furthermore, the swing mechanism is the same as that provided in a conventional buttonhole sewing machine capable of mechanically adjusting the width of the swing stitch, so the description thereof will be omitted. In a word, the amplitude of the pendulum in this embodiment is mechanically adjusted and can be preset.

In the frame portion 12, a hook base 31 having a left-hand hook 6 passing through the bobbin thread and a right-hand hook 5 that assists the left-hand hook 6 is provided facing the needle bar 11 . The left and right rotary hooks 6, 5 are connected to the lower shaft by a drive mechanism not shown. Needle bar 11 and rotary hook seat 31, it is the same synchronous action as the sewing machine in the past, and lower thread is wound on upper thread to form overlock stitch by both cooperative actions.

And, the needle bar 11 and the hook base 31 are connected with a rotating mechanism (rotating device) 15 having a rotating motor (pulse motor for rotating) 84 and a timing belt, and synchronously rotate around a vertical rotating shaft, and Here, radial stitches are formed around the drop-shaped eye portion h1 of the buttonhole H (round eye seam portion w2 ).

On the upper surface of the base portion 12, a cloth feed stand (cloth feed mechanism) 13 for positioning the processed cloth thereon is provided. On the upper surface of the cloth feed table 13, there are provided presser feet 2 for pressing the cloth to be processed on both sides where buttonholes are to be formed.

The cloth feed table 13 is a thin rectangular box as a whole, and is provided with the X-axis motor 82 and the Y-axis motor 83 in the base part 12, and controlled by the CPU 113, it can be moved to the left and right directions (X direction) and Move in the forward and backward direction (Y direction).

In the state where the cloth feed table 13 is positioned at the specified origin position, and above and below the predetermined positions for forming the buttonholes on the processed cloth carried on it, opposite fixed cutters (not shown) and bearings are provided. Knife table 4.

The knife holder 4 is arranged at the rear of the needle bar 11 , and a fixed cutter is arranged on the base portion 12 facing the knife holder 4 . The knife holder 4 is driven up and down by the cloth cutting motor (pulse motor) 85 located above it.

When sewing, at first, the cloth cutting motor 85 is driven at the origin position, and the knife holder 4 is lowered toward the fixed cutter, and the processed cloth positioned between the knife holder 4 and the fixed cutter is cut, and formed Buttonhole (here round buttonhole) H.

Then, with the operation of the start switch 92 (Fig. 7), the cloth feed table 13 is driven to move to the sewing start position ahead of the origin position, that is, the processed cloth carried on the cloth feed table 13 is moved to the front of the sewing machine needle 18. below. The overlock around the buttonhole H is sewn from the lower end of the right seam w1, through the eyelet seam w2, to the left seam w3, and finally to the straight reinforcement seam w4. In order to sew in this order, the cloth feed table 13 starts to move from the above-mentioned sewing start position in the Y direction, and moves forward until the apex of the buttonhole H (the front end of the round buttonhole h1) faces the sewing machine needle, and then moves to the sewing machine needle. The back returns to the sewing end position which is almost the same as the sewing start position.

Once the sewing is finished, the cloth feed table 13 is controlled to return to the original position from the sewing end position. And, when positioning the processing cloth in this embodiment, the cloth feeding table 13 has already moved to the prescribed positioning position.

In the sewing machine 10, the upper thread cutting device 7 and the lower thread cutting device 30 for cutting the upper thread and the lower thread respectively are provided on the above-mentioned rotary hook base 31 . As will be described later, on the sewing machine 10, after the sewing is finished and before the cloth feed table starts to move to the origin position, the upper thread is cut by the upper thread cutting device 7, and at the halfway position to the origin, the lower thread cutting device 30 is used to cut the upper thread. Cut the bottom line.

In the present invention, since the needle thread cutting device 7 has a well-known structure, its detailed description will be omitted. However, since the bobbin thread cutting loader 30 which is the characteristic of the present invention utilizes the same driving source as the upper thread cutting device 7, the driving mechanism of the upper thread cutting device 7 will be described first below.

The upper thread cutting device 7 of the upper thread cutting mechanism, as shown in FIG. constitute.

The upper thread cutting operation arm 78a for operating the upper thread cutter 78 is rotatably mounted on the mounting member 31a fixed to the hook base 31 about an axis parallel to the front-rear direction of the sewing machine 10. A needle thread cutter 78 is fixed to an upper portion of the needle thread cutting operation arm 78a. In FIG. 2, in order to simplify the bobbin thread cutting device 30, only the frame portion 12 is schematically shown by a two-dot chain line.

On the upper thread cutting operation arm 78a, one end of an unillustrated operating arm spring is hung, and the spring for the operating arm is used to apply a pulling force to rotate in a predetermined direction, and the upper thread cutting 78 is positioned at a predetermined cutting standby position. In addition, the pivot point of the upper thread cutting operation arm 78a is the central rotary shaft 42 which will be described later.

The upper thread cutting operation arm 78a is provided with a convex portion 78c, and the upper thread cutting operation arm 78a, which is pressed downward by the upper spring force of the upper spring against the upper thread cutting operation arm 78a by the upper thread cutting driving mechanism 60, rotates in the direction opposite to the predetermined direction. In this way, the upper thread cutting operation of the upper thread cutter 78 is performed.

The upper thread cutting driving mechanism 60 is composed of a thread cutting cylinder 86 , a thread cutting link 61 , a thread cutting driving shaft 64 , and a cutting driving arm 69 .

The base of the thread cutting cylinder 86 is rotatably supported by the cylinder bracket 66 fixed to the machine base 12 by set screws 66a, 66a. And the thread cutting cylinder 86 can advance and retreat the connecting rod 86a installed on its front portion, and the stretching amount of the connecting rod 86a is usually a fixed value.

The end portion of the link 86a is rotatably connected to one end of the tangent link 61 forming a substantially T-shape via the cylinder knuckle 67 . The middle part of the thread cutting link 61 is rotatably supported on the base part 12 by the rotating shaft 61a. Furthermore, the other end of the thread cutting link 61 is rotatably connected to a thread cutting drive shaft 64 extending almost vertically. A thread cutting drive arm 69 is provided at an upper end portion of the thread cutting drive shaft 64 . And, when the rotary hook seat 31 is at a rotation angle of 180 degrees, the thread cutting driving arm 69 and the convex portion 78c of the upper thread cutter 78 overlap up and down, and if at 0 degrees, the protruding pin 26d of the bobbin thread cutting loading 30 described later and The thread cutting drive arm 69 is coincident.

According to the upper thread cutting driving mechanism 60, the cutting driving arm 69 operates while the thread cutting driving shaft 64 driven by the driving force of the thread cutting cylinder 86 moves up and down.

That is, as shown in FIG. 2, in the state where the thread cutting cylinder 86 is closed, the link 86a is extended, and at this time, the cutting drive arm 69 is in a stopped state at the top dead center. In addition, once the thread trimming cylinder 86 is turned on, the link 86a is retracted, and the cutting driving arm 69 moves downward due to the counterclockwise rotation of the thread trimming link 61, and stops at the bottom dead center. If the rotary hook seat 31 is positioned at the position of turning 180 degrees at this time, then the cutting drive arm 69 presses the convex portion 78c downward, and the upper thread cutter 78 located at the cutting standby position moves, and the upper thread is cut off. Make the thread cutting cylinder 86 in the closed state again, then the cutting drive arm 69 moves to the upper dead point, and the upper thread cutter 78 returns to the cutting standby position due to the pulling force of the above-mentioned moving arm spring.

If the hook seat 31 is located at the 0-degree rotation position, the cutting drive arm 69 drives the bobbin thread cutting device 30 to cut the bobbin thread. This will be described later.

Next, the lower thread cutting device 30 of the lower thread cutting mechanism will be described.

First, its structure will be described with reference to FIGS. 3 to 6 .

Bottom thread cutting device 30, it is arranged on the rotary hook seat 31, is made of bobbin thread cutter 20 and bobbin thread presser foot 27, and bobbin thread is cut off near needle plate 32 near needle plate 32 after sewing. Left-hand hook 6, which is fixed on the hook mounting seat 6a shown in Figure 4, and passes through the bottom thread. In addition, the hook mounting base 6a has a structure capable of swinging on a plane perpendicular to the plane of the drawing in FIG. Therefore, the left-hand hook 6 performs a predetermined reciprocating motion under the needle plate during sewing. In addition, the above-mentioned right-hand hook 5 also reciprocates synchronously with the left-hand hook 6, and assists the operation of winding the lower thread passed through the left-hand hook 6 around the upper thread passed through the machine needle 18.

Bottom thread cutter 20, it is slightly hook-shaped, and its root end is fixed on the bottom thread cutter arm 26 with stop screw, and moves simultaneously with bottom thread cutter arm 26.

One of the front ends of the lower thread cutter 20 is a blade portion 20a for cutting the lower thread. The other is a polished escape portion 20b (FIG. 5) that does not cut even if it touches the bottom thread.

The bobbin thread cutter arm 26 extends from the main portion 26a slightly bent in the middle to which the bobbin thread cutter 20 is fixed, extends from the main portion 26a to the right in FIG. The bolt support part 26b of the movable bolt 33 is extended leftward from the main part 26a, and the pin support part 26c which fixes the protruding pin 26d protruding rearward is comprised.

The lower part of the main part 26a is rotatably mounted on the central rotating shaft 42 inserted in the mounting part 31a, and rotates around it.

The 1st stopper bolt 33 of the bolt support part 26b is screwed in the screw hole of the bolt support part 26b by a predetermined amount, and the lower surface part 33a abuts on the hook seat 31. As shown in FIG. And, one end of the lower thread cutting spring 25 (Fig. 3 shows only a part, and the others are indicated by dotted lines) is hung in the middle of the bolt supporting portion 26b, and the other end of the lower thread cutting spring 25 is hung on the hook seat. The bobbin thread cutter arm 26 is usually pulled clockwise in FIG. 3 by the bobbin thread cutting spring 25, and in the initial state, the lower surface portion 33a of the first stopper bolt 33 stops at the abutment against the hook seat 31. state, and the bobbin thread cutter 20 avoids to the position that does not hinder sewing. That is, the height ( H1 ) of the first stopper bolt 33 protruding downward from the bolt support portion 26 b determines the initial position of the lower thread cutter arm 26 .

When the rotation position of the hook base 31 is 0 degrees, the protruding pin 26d of the pin support portion 26c overlaps with the above-mentioned cutting driving arm 69 (FIG. 4).

The second stopper bolt 34 is screwed vertically through the pin support portion 26c by a predetermined amount, and its lower surface portion 34a protrudes from the pin support portion 26c. When cutting the bottom thread, the rotary position of the hook seat 31 is 0 degrees, and once the protruding pin 26d is pressed by the descending of the cutting drive arm 69, the bottom thread cutter arm 26 overcomes the bottom thread cutting spring 25 and is moved counterclockwise in Fig. 3 . direction drive. At this time, the lower surface portion 34a of the second stopper bolt 34 just abuts against the hook seat 31 so that it cannot rotate counterclockwise. The length of the second stopper bolt 34 protruding downward from the pin support portion 26c in this way is the rotation distance necessary for the lower thread cutter 20 to cut the lower thread reliably, and determines the length of the lower thread cutter arm without unnecessary movement. 26 the action end position.

Where indicated by oblique lines on the inner surface of the main portion 26a, there is a flat and concave concave surface 26e. The side surface (hereinafter referred to as the concave side surface) 26f forming the concave surface 26e abuts against the coaxially rotatable bolt 36 when the bobbin thread cutter arm 26 rotates counterclockwise, and is pushed in the same direction.

A lower thread presser 27 is provided facing the lower thread cutter 20 via a needle plate 32 to be described later. The bobbin thread presser 27, as shown in FIG. 6, is a device for holding the bobbin thread by pressing the bobbin thread pressing surface 27a formed on the front end portion 27f against the bobbin thread guide surface 32f of the needle plate 32.

Bottom thread presser foot 27 has bottom thread presser pin 28 inserted in its central part. Both ends of the lower thread presser pin 28 are supported on the lower thread presser mount 24, so the lower thread presser 27 can rotate around the lower thread presser pin 28 relative to the lower thread presser mount 24. Bottom thread presser foot installation seat 24, it is to look slightly square from the rear and slightly triangular shape from the side.

In addition, under the bottom thread presser foot mounting seat 24, there is a bottom thread presser foot return spring 23, and the bottom thread presser foot return spring 23 abuts against the bottom thread presser foot mounting seat 24 and the hook seat 31, and exerts force to make the two Between the two to the direction of expansion, that is, the pressure of the bobbin thread presser foot mounting seat 24 to the direction of the hook seat 31.

A screw hole 24a (FIG. 5) is drilled on the side of the bottom thread presser foot mounting seat 24, and the stop bolt 21 is passed through the screw hole 24a. The front end of the stopper bolt 21 abuts against the side surface 31b of the mounting member 31a. The screwing amount of the stopper bolt 21 into the screw hole 24a is changed to change the distance from the side surface 31b of the mounting member 31a. Therefore, the distance between the front end portion 27f and the needle plate 32 is changed around the center rotation axis 42. Specifically, the stop bolt 21 is adjusted to adjust the distance between the bottom thread pressing surface 27a of the bottom thread presser foot 27 and the bottom thread guide surface 32f of the needle plate 32 to maintain the bottom thread with an appropriate force according to the thickness or characteristics of the bottom thread, and In this state, the nut 22 is tightened to fix the stopper bolt 21 . That is, the stopper bolt 21 and the nut 22 constitute the adjustment mechanism of the present invention.

In addition, as mentioned above, the lower thread presser mounting base 24 and the lower thread presser 27 use the lower thread presser return spring 23 to apply pressure to the lower thread pressing surface 27a in a direction close to the lower thread guide surface 32f. However, the stop bolt 21 abuts against the side surface 31b of the mounting member 31a to prevent the bobbin thread presser 27 from being pushed toward the needle plate 32 side. That is, it can also be said that the method of adjusting with the adjustment mechanism prevents the strong impact given to the needle plate 32 by the lower thread presser foot 27 .

In addition, the distance between the bobbin thread presser 27 and the bobbin thread guide surface 32f may be approximately 0 mm, for example, if the bobbin thread is to be firmly held, and if the bobbin thread is quite thick, the distance of the bobbin thread thickness may be maintained.

In the lower thread presser 27, the front end portion 27f is bent toward the lower thread guide surface 32f of the needle plate 32 in the middle. Details of the front end portion 27f will be described later.

The lower end portion 27g of the bobbin thread presser foot 27 forms an inverted U-shaped opening separated by two forks, and the stopper pin 29 is passed through the opening (FIG. 3 and FIG. 4). The head of the stopper pin 29 abuts against the lower end 27g as shown in FIG. Furthermore, a bobbin thread presser spring 40 is attached around the shaft of the stopper pin 29 inside the lower end portion 27g. The lower end 27g of the lower thread presser 27 can be swung rearward by the lower thread presser spring 40, thereby pushing the side surface 32h (the shaded part in FIG. 6 ) of the needle plate 32 toward the front end. The opposite side surface 27d of the side surface 32h of the triangular pyramid part 27c of the part 27f. Therefore, the lower end 27g is pressed by the lower end 27g of the lower thread presser spring 40, and abuts against the inner surface of the head of the stop pin 29, so that the lower end 27g of the lower end 27 of the lower thread presser 27 cannot continue to swing backward, and the opposite side 27d does not press the side too much. 32h.

In addition, FIG. 11(b) shows an enlarged view of a state where the side surface 32h and the opposite side surface 27d are in contact.

The inner side of the bobbin thread presser mounting seat 24 extends below the bolt 37 and becomes an extension portion 24c. On the extension part 24c, it overlaps with it, and it overlaps with the bottom thread presser foot fulcrum seat 35 of a flat plate whose size spreads to the bottom inner side of the main part 26a of the bottom thread cutting arm 26, and the extension part 24c and the bottom thread presser foot fulcrum seat 35 are substantially Be fixed together with screw 36 on. Also, on the extension part 24c, a longitudinal long hole for passing the screw 36 is formed, and in the state where the height position of the extension part 24c (bottom thread presser foot mounting seat 24) relative to the bottom thread presser fulcrum seat 35 is adjusted , and fix it with screw 36.

The lower part of the lower thread presser foot fulcrum seat 35 passes through the above-mentioned central rotating shaft 42, and the lower thread presser foot pivot seat 35 and the lower thread presser foot mounting seat 24 can flexibly rotate around the central rotating shaft 42.

When the bottom thread cutter arm 26 rotates counterclockwise, the bottom thread presser fulcrum seat 35 and the bottom thread presser foot mounting seat 24 push the screw 36 together, so that the bottom thread presser foot mounting seat 24, i.e. The bobbin thread presser 27 rotates counterclockwise around the center rotation shaft 42 .

The needle plate 32, as shown in FIG. 6, has a needle hole 32b through which the needle 18 passes, and is supported by a leg portion 38 having a screw hole 38a formed in the center. The needle plate 32 is fixed on the mounting part 31a by the screws on the screw holes 38a.

The needle hole 32b is made into a horizontally elongated shape in which the needle 18 can swing in the needle hole 32b when overlocking. Fig. 5 is a diagram showing needle entry positions in the needle hole 32b indicated by points P1 and P2. During sewing, point P1 is an inner needle entry position close to the buttonhole, and point P2 is an outer needle entry position far from the buttonhole (see FIG. 9( d )). In addition, the specific positions of the points P1 and P2 with respect to the pinhole 32b can be appropriately changed.

The opening portion 32c is formed continuously with the needle hole 32b, and a part of the needle plate 32 is cut away. In addition, the edge portion 32e of the left hand is formed into an arc shape from the pinhole 32b in FIG. 6, and the lower corner portion 32d (the portion indicated by the thick line) is chamfered and ground. As will be described later, before cutting after sewing, the bobbin thread relatively exits from the opening 32c and moves toward the bobbin thread guide surface 32f along the lower corner 32d. At this time, since the lower corner 32d is round and polished, The bobbin thread can move smoothly without drawing out unnecessary parts.

On the leg portion 38, a lower thread guide surface (lower thread guide portion) 32f is formed on the upper side of the screw hole 38a to be narrower and continuous with the lower surface of the needle plate 32 on the side surface. The bobbin thread guide surface 32f is a mechanism for pinching the cut bobbin thread between the bobbin thread pressing surface 27a formed on the front end portion 27f of the bobbin thread presser 27 . That is, the lower thread guide surface 32f and the lower thread presser foot 27 constitute the lower thread holding mechanism of the present invention.

The bobbin thread guide surface 32f is provided in the middle of the straight line connecting the inner needle entry position P1 and the outer needle entry position P2 in the needle hole 32b and in a vertical plane perpendicular to the straight line. The bobbin thread held on the bobbin thread holding mechanism, which almost coincides with the above-mentioned plane, is naturally guided to be sewn into the overlock stitch at the beginning of sewing.

In addition, on the front end portion 27f of the lower thread presser 27, a protruding surface 27b is formed that protrudes further than the lower thread pressing surface 27a. The protruding surface 27b is in surface contact with a rear side surface 32g formed on the upper rear side of the leg portion 38, which is stepped from the bobbin thread guide surface 32f. And as mentioned above, the triangular pyramid part 27c of a triangular pyramid shape is formed in the upper surface of the front-end|tip part 27f. The opposite side surface 27d of the triangular pyramid portion 27c is in contact with the side surface 32h of the edge portion 32e of the needle plate 32 .

When the lower thread is clamped between the lower thread guide surface 32f and the lower thread pressing surface 27a, the protruding surface 27b and the rear side surface 32g contact the opposite side surface 27d and the side surface 32h respectively, so that the lower thread never escapes.

FIG. 7 shows the control device 110 of the sewing machine 10. As shown in FIG.

The control device 110 shown in FIG. 7 is composed of ROM (Read Only Memory) 111, RAM (Random Access Memory) 112, CPU (Central Processing Unit) 113, EEPROM (Electrically Erasable and Programmable Read Only Memory) 115 and the like.

The control device 110 is connected with the operation panel 90 and the start switch 92 through the interface 114, and is connected with various actuators such as the spindle motor 81, the X-axis motor 82, the Y-axis motor 83, the rotation motor 84, the cloth cutting motor 85, and the thread cutting cylinder 86. actuator connection.

In addition, between the interface 114 and the spindle motor 81, the X-axis motor 82, the Y-axis motor 83, the rotation motor 84, and the cloth cutting motor 85, there are a spindle motor drive circuit 81a, an X-axis motor drive circuit 82a, and a Y-axis motor drive circuit 82a for driving each motor. Shaft motor driving circuit 83a, rotating motor driving circuit 84a, cloth cutting motor driving circuit 85a, and between the interface 114 and the thread cutting cylinder 86, there is a thread cutting cylinder driving solenoid valve 86a.

In addition, an X-axis origin sensor 82b, a Y-axis origin sensor 83b, and a rotation axis sensor 82b for detecting the respective origin positions of the X-axis motor 82, the Y-axis motor 83, the rotation motor 84, and the cloth cutting motor 85 are connected to the control device 110 through the interface 114. Origin sensor 84b, cloth cutting origin sensor 85b.

In ROM111, controls for controlling various actuators such as the spindle motor 81, X-axis motor 82, Y-axis motor 83, rotary motor 84, cloth cutting motor 85, thread trimming cylinder 86, and buttonhole sewing are solidified. program and control data.

The EEPROM 115 stores a plurality of graphic data, and also stores the numerical value when the numerical value of the data item in the graphic data is changed through the operation panel 90 . In addition, RAM112 has a function as a temporary memory for various processes during sewing. The pattern data refers to a series of setting data necessary for forming buttonhole stitches such as the sewing length and the number of stitches.

The CPU 113 controls a series of processes related to buttonholes including cloth cutting, sewing, upper thread cutting, and bobbin thread cutting in accordance with the control program and control data of the ROM 111 since the start signal is input from the start switch 92 .

That is, the CPU 113 drives and controls the rotation of the spindle motor 81 through the spindle motor drive line 81 a connected through the interface 114 . Spindle motor 81, which drives machine needle 18 up and down and drives the upper shaft of left and right swing needles, and the hook mechanism that cooperates with machine needle 18 and forms stitches.

Further, CPU 113 drives cloth feed table 13 in a predetermined direction while driving and controlling X-axis motor 82 and Y-axis motor 83 by using X-axis motor drive line 82 a and Y-axis motor drive line 83 a connected through interface 114 .

Furthermore, the CPU 113 drives and controls the rotation motor 84 through the rotation motor drive line 84 a connected through the interface 114 . The needle 18 and the hook base 31 are rotated (rotated) by the rotary motor 84 to form the eye stitch portion w2 of radial stitches around the eye h1 (see FIG. 9( b )).

In addition, the CPU 113 drives and controls the cloth cutting motor 85 through the cloth cutting motor drive line 85 a connected through the interface 114 to move the knife holder 4 up and down.

Also, the CPU 113 drives the thread trimming cylinder 86 through the thread trimming cylinder driving solenoid valve 86a connected through the interface 114 at a predetermined timing after the sewing is completed.

In the series of processes described above, the CPU 113 drives the X-axis motor 82 and the Y-axis motor 83 while detecting the states of the X-axis origin sensor 82b, the Y-axis origin sensor 83b, the rotation origin sensor 84b, and the cloth cutting origin sensor 85b. , Rotary motor 84, cloth cutting motor 85, and control the movement of the cloth feeding table 13, the rotation angle of the needle bar 11 and the hook seat 31, the lowering position of the knife table 4, etc.

Next, referring to FIGS. 3 , 4 , and 8 to 13 , the operation of the sewing machine 10 having the above-mentioned configuration will be described centering on the bobbin thread cutting device 30 . In FIGS. 8 and 9 , the buttonhole stitch W formed on the processed material S ( FIG. 4 ) overlaps with parts such as the needle plate 32 under the processed material S. As shown in FIG. In addition, the bottom thread T drawn out from the left-hand hook 6 is indicated by a dotted line and a black dot, and particularly a black dot indicates the position of the bottom thread at substantially the same height as the needle plate 32 . And omit the upper thread connected with the needle 18 from the buttonhole stitch W.

The sewing of the buttonhole H and the buttonhole stitch W ends with the sewing of the straight backtack W4. At this time, as shown in FIG. 8(a), the longitudinal direction of the needle hole 32b of the needle plate 32 is parallel to the pendulum direction of the straight reinforcement seam W4, and the rotary position of the hook seat 31 is 270 degrees. At this time, the positional relationship between the lower thread cutter 20, the front end portion 27f of the lower thread presser 27, the rotary hook 6, and the needle plate 32 is shown in the figure. It is the state of FIG. 3 . The lower thread guide surface 32f of the needle plate 32 is in contact with the lower thread pressing surface 27a of the lower thread presser 27 .

Then, the rotating mechanism 15 is driven by the rotating motor 84, and the hook seat 31 is returned 90 degrees clockwise, and its rotating position is 180 degrees. At this time, the lower thread T in the needle hole 32b moves to the position seen from the rear of the opening 32c. At this 180-degree rotational position, the thread cutting cylinder 86 is driven to cut the upper thread with the upper thread cutter 78 .

Then, drive the Y-axis motor 83 to move the cloth feeding table 13 backward by a predetermined distance (equivalent to the distance from the pinhole 32b to the opening 32c, such as about 4mm), as shown in Figure 8(c) or Figure 10 , the bobbin thread T connected to the sewing end position of the buttonhole stitch W also moves together, and reaches the opening 32c. As shown in FIG. 10 , the protruding pin 26 d of the bobbin thread cutter arm 26 is located at a position completely opposite to the thread cutting driving arm 69 . In addition, the white dots near the needle plate 32 in FIGS. 10 to 12 indicate the bottom thread T in the previous state.

Subsequently, the hook base 31 is rotationally driven with a rotational position of 0 degrees as a target. Therefore, the needle plate 32 rotates clockwise and reaches the bottom line T of the opening 32c. As shown in FIG. 8(d) and FIG. to guide in the counterclockwise direction.

Next, as shown in FIG. 8( e ) and FIG. 12 , the rotation position is 0 degrees, and the bobbin thread T reaches a position between the bobbin thread guide surface 32 f of the needle plate 32 and the bobbin thread pressing surface 27 a of the bobbin thread presser foot 27 . The previous FIG. 4 shows the state of the rotation position of 0 degrees, and the protruding pin 26d of the bobbin thread cutter arm 26 is located below the thread cutting driving arm 69 . In this way, the bobbin thread is guided by the operation of the rotating mechanism 15 and the cloth feed table 13, which is the guiding mechanism of the present invention.

Dotted lines A, B, and C in FIG. 4 represent movement of the lower thread T relative to the needle plate 32 when the hook base 31 rotates. That is, in FIGS. 8( a ), ( b ), the bottom line T is inside the pinhole 32 b as indicated by the dotted line A. As shown in FIG. Then, in the state of FIG. 8( c ) after the cloth feed table 13 has moved, it reaches the opening portion 32 c as indicated by the dotted line B. As shown in FIG. And, because needle plate 32 rotates 180 degrees and is in the state of Fig. 8 (e), at this moment then as shown in the dotted line C of Fig. 4, it has covered the necessary way of bobbin thread cutter 20.

After Fig. 8(e), the thread cutting cylinder 86 is driven to lower the cutting drive arm 69, and the protruding pin 26 is pressed downward. In this way, the pulling force of the lower thread cutting spring 25 is overcome, and the lower thread cutter arm 26 and the lower thread cutter 20 start to rotate counterclockwise in FIG. 3 around the central rotating shaft 42 at the same time. At this time, the lower thread is evacuated and slid by the evacuation portion 20b of the lower thread cutter 20 without cutting.

And on the way, the bolt 36 is pressed with the concave side surface 26f inside the lower thread cutter arm 26, and the lower thread presser foot 27 also rotates in the same direction around the central rotating shaft 42 together with the lower thread presser foot mounting seat 24. Therefore, as shown in FIG. 8( f ), the blade portion 20 a of the lower thread cutter 20 completely crosses the lower thread T, and the front end 27 f of the lower thread presser 27 is also slightly separated from the needle plate 32 . The lower thread stopped at the contact portion between the lower thread presser 27 and the needle plate 32 is in a state of being in contact with the lower thread guide surface 32f as shown in FIG. 6 . The rotation of the bobbin thread cutter arm 26 (bottom thread cutter 20 ) and the bobbin thread presser 27 stops at the position where the second stopper bolt 34 abuts against the rotary hook 31 as shown in FIG. 13 .

In addition, the lower thread presser 27, as described above, has its front end 27f pressed against the needle plate 32 by the lower thread presser spring 40, but since it is not excessively restricted by the stopper pin 29, the front end 27f does not It exceeds the most protruding portion of the arc-shaped edge portion 32e.

Once the thread trimming cylinder 86 returns to its original state, the thread trimming drive arm 69 returns upward. Therefore, the bobbin thread cutter 20 and the bobbin thread cutter arm 26 are subjected to the tension of the bobbin thread cutting spring 25, and the bobbin thread presser foot 27 and the bobbin thread presser foot mounting seat 24 are pressed by the bobbin thread presser foot return spring 23 to start a reset action.

During the reset operation, since the front end 27f of the lower thread presser 27 is pressed against the needle plate 32 by the lower thread presser spring 40, one side of the opposite side 27d of the triangular cone 27c contacts the edge 32e of the needle plate 32. Move aside. As soon as the bobbin thread presser foot 27 returns to the position where the stop bolt 21 abuts against the side surface 31b of the mounting member 31a, the bobbin thread pressing surface 27a presses the bobbin thread T crossing the bobbin thread guide surface 32f, and is clamped by both. At this time, the protruding surface 27b and the rear side surface 32g, and the opposite side surface 27d and the side surface 32h are in contact with each other, respectively, and the escape of the bottom thread T is not allowed.

After the lower thread T is clamped by the lower thread guide surface 32f and the lower thread pressing surface 27a, the blade portion 20a of the lower thread cutter 20 immediately cuts the lower thread T and returns to the initial position as shown in FIG. 9(a).

When the next sewing starts, at first, the cloth cutting motor 85 is driven to form the buttonhole H at the origin position of the cloth feed table 13, and then the cloth feed table 13 is sent forward to the specified sewing position, as shown in Figure 9 (c). shown, and start sewing from right side seam W1. The lower thread T connected to the left-hand hook 6 that has been cut and held after the last sewing is between the inner needle entry position and the outer needle entry position of the needle hole 32b due to the guide surface formed by the lower thread guide surface 32f and the lower thread pressing surface 27a. , so along with the needle plate 32 moves relatively to the rear, as shown in Figure 9 (d), the bottom thread T that was cut off and kept connected with the left-hand hook 6 after the last sewing is naturally sewn into the stitching.

In addition, in Fig.9 (c), (d), the white dot shows the position of the needle in sewing, and the bobbin thread for sewing supplied from the left-hand hook 6 is omitted.

According to the above-mentioned sewing machine 10, after the buttonhole is completed, the bobbin thread T passed from the left-hand hook 6 and connected to the processing cloth S is first guided to the opening 32c by the cloth feed table 13, and then the needle plate 32 is moved by the rotating mechanism 15. Rotate and relatively guide the lower thread guide surface 32f along the lower corner 32d of the outer periphery of the needle plate 32. The bobbin thread cutting device 30 cuts the bobbin thread held by the bobbin thread guide surface 32f and the bobbin thread pressing surface 27a of the bobbin thread presser foot 27 in its vicinity before the cloth to be processed is fed by the cloth feed stand 13 .

That is, since the lower thread T is guided from the needle hole 32b to the lower thread guide surface 32f at the rear of the needle plate 32 through the opening 32c, it is not necessary to draw out the long thread as described in the aforementioned JP-A-9-225166 publication.

Thereby, the end of thread remaining on the processing cloth side after cutting is only the distance from the end point of the buttonhole stitch to the needle plate 32, and is held by the bobbin thread holding mechanism, that is, the end of thread remaining on the rotary hook 6 side can be shortened to The length of the needle plate 32. Therefore, since the end of the thread that is sewn in next time is shortened, it is not ugly.

Furthermore, since the bobbin thread cutting device 30 is provided on the hook base 31, the bobbin thread can be cut at a predetermined position relative to the position of the buttonhole stitch. The so-called cutting position relative to the specified position of the buttonhole stitch position means that the bobbin thread cutting mechanism has nothing to do with the seam length, and there is no need to adjust or replace the parts of the bobbin thread cutting mechanism according to the seam length, and the sewing length cannot exceed the specified While the range is limited, free-length keyhole stitches can be sewed.

In addition, since the amount of bobbin thread drawn out is small, the waste of machine thread is also small.

Because the end of the thread is short, the bottom thread pressing surface 27a of the bottom thread presser foot 27 is used to press and hold the bottom thread on the bottom thread guide surface 32f, and the bottom thread guide surface 32f is set in the needle hole 32b to connect the inner needle drop position P1 and the outer side. The needle drop position P2 is in the middle of the straight line and in the vertical plane perpendicular to the straight line, so the bottom thread is naturally guided to be sewn into the overlock stitch when the next sewing starts.

In addition, the needle plate is made very small, and the lower thread pressing surface 27a and the lower thread guide surface 32f opposite to it are made to the maximum allowable length in the direction of the needle hole 32b, so that the needle hole 32b located at the position where the stitches are formed is close to the needle. Hole 32b, so the end of thread can be kept just completely sewn in continuously.

In addition, by appropriately controlling the conveying amount of the cloth feeding table 13, the bobbin thread remaining length on the processing cloth S side can be selected, and can also be appropriately changed to a certain extent, so the degree of freedom is high.

And, since the bobbin thread is guided by the cloth feeding table 13 and the rotating mechanism originally provided on the buttonhole sewing machine, it can save cost and space if compared with setting a dedicated mechanism for guiding.

In addition, before cutting, that is, in a state where the bobbin thread cannot freely move from the processing material S to the hook 6, since the bobbin thread is held first, it can be reliably held. In addition, the lower thread is cut while maintaining a certain tension, so the lower thread can be cut reliably.

Since the bobbin thread presser 27 and the bobbin thread cutter 20 are driven by the same drive mechanism as the upper thread cutting drive mechanism 60, the overall structure can be simplified. And because the driving source is the same, if one adjustment is made, there will be no deviation in the synchronization of clamping and cutting the bottom thread.

In addition, since the minimum distance between the bobbin thread presser 27 and the bobbin thread guide surface 32f can be adjusted by the adjustment mechanism composed of the stopper bolt 21 and the nut 22, the holding force can be optimized according to the thickness and properties of the bobbin thread. The bottom thread will come out due to weak holding force, or conversely, the bottom thread will be broken due to too strong holding force. In addition, on the other hand, it can also adjust the force when the lower thread presser 27 contacts the lower thread guide surface 32f, and prevent the impact on the needle plate 32, which is an important part, when the lower thread is held.

Since the lower thread guide surface 32f is arranged below the needle hole 32b, a hole for passing the filling thread almost on the same plane as the needle hole 32b on the needle plate can be formed, for example, as shown in the symbol R of FIG. The location forms the hole through the fill line. Thus, parts can be generalized regardless of whether lines are to be filled or not.

Also, the present invention is not limited to the above-mentioned embodiments.

For example, in this embodiment, the bobbin thread cutting mechanism is arranged on the rotary hook. In addition to shortening the thread end connected to the processing cloth from the rotary hook, it is not necessary to adjust and replace the structure of the bobbin thread cutting mechanism parts according to the seam length. The bobbin thread cutting mechanism for shortening the end of thread connected from the rotary hook to the material to be processed is not limited to the above-mentioned structure. That is, it is also possible to prevent the bobbin thread from being pulled out too long when the bobbin thread holding mechanism holds the processed cloth. Before transferring the material to be processed after holding the lower thread, shorten and cut the end of the thread connected from the rotary hook to the material to be processed by driving the lower thread cutting mechanism.

In addition, it is also applicable to a buttonhole sewing machine that forms backtacks of different shapes from the above-mentioned embodiment, or performs buttonhole stitches without backtacks, and is also applicable to a sewing machine that performs buttonholes around straight buttonholes other than round holes.

In addition, in the above, the lower thread is cut immediately after holding, but, of course, instead of cutting immediately after holding, the lower thread may be cut before the cloth is processed.

In addition, in the above-mentioned embodiment, the bobbin thread guide surface 32f of the needle plate and the bobbin thread pressing surface 27a of the bobbin thread presser are used to hold the cut bobbin thread, but it is also possible to install a plate spring at the rear of the needle plate. Keep the parts. According to such a structure, the above-mentioned bobbin thread presser 27 can be unnecessary, and the structure is simpler.

In addition, the lower corner portion 32d of the edge portion 32e of the needle plate 32 may be used to guide the lower thread. The lower thread drawn from the opening 32c of the needle plate 32 to the outside of the needle plate 32 may be guided along other members such as the mounting member 31a. structure.

According to the present invention described in the first aspect of the present invention, after the buttonhole stitching is completed, the bobbin thread that is connected to the processing cloth through the needle hole from the rotary hook can be guided and pulled out from the opening of the needle plate by the guide mechanism, and held in the needle plate. It is installed on the bobbin thread holding mechanism around the needle plate, and cuts the bobbin thread between the rotary hook and the material to be processed with the bobbin thread cutting in this state. That is to say, only the lower thread is led from the needle hole to the lower thread holding mechanism around the needle plate through the opening, so it is not necessary to draw so long as described in the above-mentioned Japanese Patent Laying-Open No. 9-225166 announcement.

Therefore, the bobbin thread cutting mechanism can cut the bobbin thread while shortening the bobbin thread connected to the material to be processed from the hook as much as possible. That is, the thread ends remaining on the processed fabric side may be shortened to the length of the needle plate to the extent of the distance from the overlock stitch to the needle plate. Therefore, when locking the buttonhole next time, the thread ends can be reliably sewn in without being unsightly due to shortening of the thread ends to be sewn in.

In addition, thread waste is reduced due to the small amount of bobbin thread drawn out.

According to the present invention described in the second aspect of the present invention, since the lower thread is held by the method of pressing the lower thread against the lower thread guide portion by the lower thread pressing member, and is guided by the guide portion when the buttonhole is locked next time, stitches can be reliably sewn. And, if the needle plate is made very small, the bottom thread guide is close to the pinhole where the stitches are formed, and the thread end that can be completely sewn into the limit of the stitches can be kept continuously, and will not come out of the stitches.

Therefore, the bobbin thread holding mechanism also serves as a guide member in addition to holding, so the structure of this part can be simplified.

According to the present invention described in claim 3, the bobbin thread presser member is driven by the same driving mechanism as the bobbin thread cutting mechanism, so that the overall structure can be simplified. In addition, since the driving source is the same, there will be no deviation in the synchronization between the bottom thread presser foot and the bottom thread cutting after one adjustment.

According to the present invention described in claim 4, since at least one of the lower thread cutting mechanism and the lower thread presser member is driven by the upper thread cutting drive mechanism, the overall structure can be simplified.

According to the present invention described in the fifth aspect of the present invention, since the minimum approach distance between the bobbin thread guide part and the bobbin thread presser part for holding the bobbin thread can be adjusted by the adjustment mechanism, and the rationalization of the holding force can be achieved according to the thickness and nature of the bobbin thread being held, Therefore, the bobbin thread will not come off at the beginning of sewing due to weak holding power, or conversely, the bobbin thread will not be cut due to strong holding power. In addition, from another perspective, it is possible to adjust the pressure when the lower thread presser foot part is in contact with the lower thread guide part, and it is possible to prevent impact on the needle plate, which is an important part, when holding the lower thread.

According to the present invention described in the sixth aspect of the present invention, since it first guides the bobbin thread passing through the needle hole to the opening with the cloth feeding mechanism, and then uses the rotating mechanism to rotate the needle plate and relatively guide it along the outer peripheral surface of the needle plate. the lower thread and guide it to the lower thread holding mechanism. That is to say, it is not necessary to set up a new mechanism for the guide mechanism but utilize the existing mechanism provided on the buttonhole sewing machine, so compared with setting a dedicated mechanism, it can save cost and space.

In addition, by properly controlling the feeding amount of the cloth feeding mechanism, it is possible to change the drawing-out amount of the bobbin thread. As a result, the length of the bobbin thread remaining on the processing cloth side can be selected, and it can also be changed appropriately to a certain extent, and the degree of freedom is high.

According to the invention according to claim 7, the bobbin thread holding mechanism is installed between the straight line connecting the inner needle entry position and the outer needle entry position in the needle hole and coincides with a vertical plane perpendicular to the straight line. , so the bottom thread held by the bottom thread holding mechanism is naturally guided between the inside needle drop position and the outside needle drop position when the buttonhole starts, and is reliably sewn into the stitch.

According to the invention described in claim 8, since the lower thread holding mechanism is provided under the needle hole, it is easy to form a hole for passing the filling thread on the needle plate, and the parts can be used in common regardless of whether the filling thread is required or not. .

According to the invention of claim 9, since the bobbin thread cutting mechanism cuts the bobbin thread connected to the processing cloth from the rotary hook after the bobbin thread holding mechanism holds the bobbin thread holding mechanism and before the processing cloth is transferred by the cloth feeding mechanism, it does not Can draw the long bottom thread that is connected with processing cloth from rotary hook as described in above-mentioned Japanese patent unexamined flat 9-225166 announcement. Thereby, the bobbin thread cutting mechanism cuts off the bobbin thread which is connected with the processed cloth from the rotary hook in a state shortened as much as possible. That is, the thread remaining on the side of the processed fabric is only the distance from the end point of the buttonhole stitch to the needle plate, and is held by the bobbin thread holding mechanism, that is to say, the thread remaining on the side of the hook is shortened to the distance from the needle plate. length. Therefore, the thread that is sewn in the next time the buttonhole is sewn in is short, does not look unsightly, and can be sewn in reliably.

In addition, since the bobbin thread is drawn out less, waste of machine thread is reduced.

According to the invention described in claim 10 of the present invention, since the bobbin thread cutting mechanism is provided on the hook seat, the cutting position is fixed, and the bobbin thread cutting mechanism can be independent of the slit length, so it is not necessary to adjust or replace the parts of the bobbin thread cutting mechanism according to the slit length. etc. It is not limited by the fixed seam length of the buttonhole, and buttonholes of free length can be sewn.

Claims (10)

1. A buttonhole sewing machine having: It is provided on the arm of the sewing machine, and supports the needle passing through the upper thread and moves up and down, and makes the needle fall alternately at the outer needle entry position far from the buttonhole and the inner needle entry position near the buttonhole formed on the processed fabric, and The needle bar that swings the needle according to the specified swing direction, A cloth feeding mechanism that is installed on the sewing machine base and at least moves the processed cloth in a direction perpendicular to the swing needle direction, facing the needle bar, it is provided on the sewing machine base, and has a hook seat that cooperates with the needle bar and winds the bobbin thread around the upper thread, On the hook seat, above the hook, there is a needle plate formed with two pinholes including the inner needle drop position and the outer needle drop position, Rotating mechanism that rotates the needle bar and hook base when locking the buttonhole The bobbin thread cutting device that cuts the bobbin thread connected between the hook and the processed fabric after the buttonhole stitching is completed, Keep the bottom thread connected with the rotary hook before cutting with the bottom thread cutting device, and use the cloth feeding mechanism to transfer the processed cloth when cutting the next buttonhole after cutting, and keep the thread end naturally sewn into the stitches The bottom line holding mechanism in is characterized in that: On the buttonhole sewing machine that forms buttonhole stitches around the buttonhole, the bobbin thread holding mechanism is arranged around the needle plate, and the needle plate is provided with an opening that is continuously opened from the needle hole to one side, and has a buttonhole After the end, and before the lower thread is cut, the lower thread that passes through the needle hole from the hook and is connected to the material to be processed can be held and pulled out from the opening by the lower thread holding mechanism. 2. The buttonhole sewing machine according to claim 1, characterized in that: the bottom thread holding mechanism is provided on the needle plate, and guides the cut bottom thread end into the buttonhole stitch formed next time, and The lower thread presser member is configured to press the lower thread on the lower thread guide portion. 3. The buttonhole sewing machine of claim 2, wherein: The bobbin thread presser is driven by the same drive mechanism as the bobbin thread cutting mechanism, and presses the bobbin thread against the bobbin thread guide. 4. The buttonhole sewing machine according to claim 2 or 3, comprising: an upper thread cutting device for cutting the upper thread after the buttonhole is finished, and an upper thread cutting drive device for driving the upper thread cutting device, characterized in that: At least one of the lower thread cutting mechanism and the lower thread presser member is driven by the upper thread cutting device. 5. The buttonhole sewing machine according to any one of claims 2-4, characterized in that it has an adjustment mechanism that can adjust the minimum distance between the bobbin thread guide and the bobbin thread presser member to keep the bobbin thread close. 6. The buttonhole sewing machine according to any one of claims 1 to 5, wherein the guiding mechanism is composed of the rotating mechanism and the cloth feeding mechanism, and after the buttonhole is locked, the cloth feeding mechanism is first used to The mechanism transports the processed cloth to the opening of the needle plate, and then uses the rotating mechanism to rotate the needle plate together with the hook seat, and guides the bobbin thread connected with the processed cloth from the hook through the needle hole along the outer peripheral surface of the needle plate The bottom line holds the body. 7. The buttonhole sewing machine according to any one of claims 1 to 6, characterized in that the bobbin thread holding mechanism is arranged between the straight line connecting the inner needle drop position and the outer needle drop position in the needle hole The position where the vertical plane coincides with the vertical direction of the straight line. 8. The buttonhole sewing machine according to any one of claims 1-7, characterized in that the bobbin thread holding mechanism is arranged below the needle hole. 9. The buttonhole sewing machine according to any one of claims 1 to 8, wherein the lower thread cutting mechanism cuts the lower thread after the lower thread is held by the lower thread holding mechanism and before the cloth for processing is transferred by the cloth feeding mechanism. cut off. 10. The buttonhole sewing machine according to any one of claims 1-9, characterized in that: The bottom thread cutting mechanism is arranged on the hook seat.

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