HK1141317B - Threader of sewing machine - Google Patents

Description

Threading device of sewing machine

Technical Field

The present invention relates to a threading device of a sewing machine for threading a needle hole by a hook portion attached to a lower end portion of a threading shaft by lowering and rotating the threading shaft close to a needle bar.

Background

Conventionally, in a sewing operation for forming a seam in a cloth by using a sewing machine, a sewing machine equipped with a threading device capable of easily threading a needle hole of a sewing needle has been put to practical use (see patent documents 1 and 2). For example, in patent document 1, when the operator lowers the thread passing lever, the thread passing shaft and the slider guide shaft are lowered, and the height positions of the thread passing shaft and the slider guide shaft are regulated by a step in which a slide pin at the upper end of the thread passing shaft abuts against a locking portion on the needle bar side. When the thread passing lever is further lowered, the thread passing shaft having the slide pin is rotated by a predetermined angle by the cam mechanism including the slide pin, and the hook attached to the lower end portion of the thread passing shaft is passed through the needle hole, and then thread is passed.

However, in patent document 1, it is necessary to manually hang a thread on a hook, and there is a problem that an operator needs to perform a threading operation with both hands. For this reason, in patent document 2, the upper thread supplied from the bobbin is hung in advance at a predetermined position of the sewing machine, and when the operator lowers the thread take-up lever, the height positions of the thread take-up shaft and the slider guide shaft are regulated by a step where a slide pin at the upper end portion of the thread take-up shaft abuts against a locking portion on the needle lever side.

When the thread passing lever is further lowered, the thread passing shaft provided with the slide pin is rotated by a predetermined angle by the cam mechanism including the slide pin, and the hook attached to the lower end portion of the thread passing shaft is passed through the needle hole. The hook is hooked on the upper thread which is hooked with the thread in a state of passing through the needle hole, and the corresponding hook is separated from the needle hole when the threading rod is lifted, so that the threading is performed. Thus, the operator can perform the threading operation only by the operation of lowering and raising the threading lever.

Patent document 1: japanese laid-open patent publication No. 2005-160592

Patent document 2: japanese laid-open patent publication No. 2002-200386

However, as is apparent from patent document 2 with reference to fig. 5 and 7 of patent document 2, in addition to the needle bar, two operation shafts, i.e., the thread passing shaft and the slider guide shaft, are required in order to control the operation of the hook mechanism fixed to the lower end portion of the thread passing shaft and to reliably thread the thread on the thread passing line. Therefore, the head portion including the needle bar of the sewing machine has a large inertia, and there is a problem that it is difficult to increase the speed when performing a delicate operation such as zigzag sewing.

Further, since the number of components is increased, it is difficult to make the entire head compact and to reduce the cost.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a threading device of a sewing machine, which can make the entire head portion compact and which enables an operator to perform a threading operation reliably with one hand.

In order to achieve the above object, a threading device of a sewing machine according to a first aspect of the present invention includes: a thread passing shaft which is close to a needle rod for moving the supported sewing needle up and down, can move up and down and is supported in a manner of rotating around the shaft; a threading hook fixed to a lower end of the threading shaft and having a hook portion capable of passing through a needle hole of a sewing needle and a first guide portion for guiding the hook portion to the needle hole; a positioning member for limiting a descending critical position of the thread passing shaft to a position where the hook portion and a needle hole of the sewing needle are consistent in height; a first rotating mechanism which rotates the first guide part by a predetermined angle near a descending critical point of the thread passing shaft so that the hook part passes through a needle hole of the sewing needle; and a thread guide member for guiding an upper thread to the hook portion in the vicinity of a descending critical point of the thread passing shaft, wherein the thread guide member has a thread hanging portion for hanging the thread and a second guide portion for guiding the thread hanging portion in a needle direction, and a second rotating mechanism for rotating the second guide portion by a predetermined angle in the vicinity of the descending critical point of the thread passing shaft so that the thread hanging portion crosses over a position of the needle and intersects the needle, the first rotating mechanism and the second rotating mechanism rotate the thread passing hook and the thread guide member in opposite directions to each other, and have a thread guide member fitted externally or internally to the thread passing shaft and fixed to a sewing machine main body and having a first cam hole and a second cam hole in a peripheral surface thereof, the first rotating mechanism having the first cam hole and a first cam shaft provided on the thread passing shaft and connected to the first cam hole, the second rotating mechanism includes the second cam hole and a second cam shaft provided in the thread guide member and fitted into the second cam hole, wherein the first cam hole has a tilt direction opposite to a tilt direction of the second cam hole, a width of the first cam hole in a vertical direction near an uppermost portion of the first cam hole is larger than a shaft diameter of the first cam shaft, and a biasing member configured to bias the thread hook and the thread guide member apart from each other is provided between the thread hook and the thread guide member.

A fourth aspect of the present invention is the threading device of the sewing machine according to the first aspect of the present invention, further comprising an operation body which is vertically movable and operates the threading shaft.

In the first aspect of the invention, the thread passing shaft is provided at a position close to the needle bar that moves the supported sewing needle up and down, and is supported so as to be movable up and down and rotatable about the shaft. A threading hook having a hook portion capable of passing through a needle hole of a sewing needle and a first guide portion for guiding the hook portion to the needle hole is attached to a lower end portion of the threading shaft. The first rotating mechanism rotates the first guide part by a specified angle near a descending critical point of the threading shaft so that the hook part passes through a needle hole of the sewing needle. The thread guide member rotatably guides the thread hanging portion in a direction of the sewing needle, and the second rotating mechanism rotates the second guide portion by a predetermined angle in the vicinity of a descending critical point of the thread passing shaft so that the thread hanging portion crosses the sewing needle. The rotation direction of the threading hook of the first rotating mechanism and the rotation direction of the thread guide member of the second rotating mechanism are opposite to each other, and the hook portion capable of passing through the needle hole of the sewing needle and the thread hanging portion capable of hanging the thread can be approached to or separated from each other by the vertical movement of one threading shaft. Thus, the upper thread is hooked on the thread hooking portion that rotates integrally with the second guide portion, and after the hook portion that rotates integrally with the first guide portion is inserted into the needle hole, the upper thread is hooked on the hook portion. The needle thread is inserted into the needle hole with the hook portion pulled back from the needle hole. Accordingly, the threading can be reliably performed in response to the vertical movement of one threading shaft, the entire head can be made compact, and the cost can be reduced. Further, even when sewing is required to be performed with a fine movement, since the inertia of the moving portion is small, it is not necessary to reduce the sewing speed in order to maintain the sewing accuracy.

The thread passing guide member is fixed to the sewing machine body by being fitted externally or internally to the thread passing shaft, and has a first cam hole and a second cam hole in its peripheral surface. The first rotating mechanism is composed of a first cam hole and a first cam shaft provided on the threading shaft and engaged with the first cam hole, and the second rotating mechanism is composed of a second cam hole and a second cam shaft provided on the thread guide member and engaged with the second cam hole. The inclination direction of the first cam hole and the inclination direction of the second cam hole are opposite directions, and when the first rotating mechanism rotates clockwise (counterclockwise) around the threading shaft, the second rotating mechanism rotates counterclockwise (clockwise) around the threading shaft. Thus, the relative rotation of the thread hooking portion for guiding the upper thread and the hook portion for threading the upper thread into the needle hole can be controlled by the vertical movement of one thread threading shaft, and the threading can be reliably performed. Therefore, the entire head can be made compact, and cost reduction can be achieved.

The width of the first cam hole in the vertical direction near the uppermost portion is made larger than the shaft diameter of the first camshaft. Thus, the second guide portion, i.e., the thread hooking portion on which the upper thread is hooked, can be further moved downward after the rotation of the first guide portion, i.e., the hook portion of the thread passing, is stopped. Further, by providing a biasing member, such as a spring, between the threading hook and the thread guide member for biasing the threading hook and the thread guide member apart from each other, the thread guide member can be moved to the original position, that is, the position where the upper thread can be hooked on the hook portion before the hook portion is disengaged from the needle hole. Therefore, for example, by inserting the hook portion into the needle hole in a state where the string portion is lowered further than the threading hook and pushing up the string portion before the hook portion is separated from the needle hole, the hook portion can be pulled out from the needle hole in a state where the upper thread is reliably hooked on the hook portion, and threading can be reliably performed.

In the fourth aspect of the present invention, an operation body that is vertically movable and operates the thread passing shaft is provided. The operator can move the threading shaft up and down and rotate the threading shaft by moving the operation body up and down, and can perform the threading operation with one hand.

The effects of the present invention are as follows.

According to the first aspect of the invention, the hook portion that can pass through the needle hole of the sewing needle and the thread hooking portion that hooks the thread can be moved closer to or away from each other by the vertical movement of the one thread passing shaft, in which the rotation direction of the first guide portion of the first rotating mechanism and the rotation direction of the second guide portion of the second rotating mechanism are opposite to each other. Thus, the upper thread is hooked on the thread hooking portion that rotates integrally with the second guide portion, and after the hook portion that rotates integrally with the first guide portion is inserted into the needle hole, the upper thread is hooked on the hook portion. The needle thread is inserted into the needle hole with the hook portion pulled back from the needle hole. Accordingly, the threading can be reliably performed in response to the vertical movement of one threading shaft, the entire head can be made compact, and the cost can be reduced. Further, even when sewing is required to be performed with a fine movement, since the inertia of the moving portion is small, it is not necessary to reduce the sewing speed in order to maintain the sewing accuracy.

The inclination direction of the first cam hole and the inclination direction of the second cam hole are opposite directions, and when the first rotating mechanism rotates clockwise (counterclockwise) about the threading shaft, the second rotating mechanism rotates counterclockwise (clockwise) about the threading shaft. Thus, the relative rotation of the thread hooking portion for guiding the upper thread and the hook portion for threading the upper thread into the needle hole can be controlled by the vertical movement of one thread threading shaft, and the threading can be reliably performed. Therefore, the entire head can be made compact, and cost reduction can be achieved.

Further, the second guide portion, i.e., the thread hooking portion on which the upper thread is hooked, may be moved further downward after the rotation of the first guide portion, i.e., the hook portion of the thread passing, is stopped. Further, by providing a biasing member, such as a spring, between the threading hook and the thread guide member for biasing the threading hook and the thread guide member apart from each other, the thread guide member can be moved to the original position, that is, the position where the upper thread can be hooked on the hook portion before the hook portion is disengaged from the needle hole. Therefore, for example, by inserting the hook portion into the needle hole in a state where the string portion is lowered further than the threading hook and pushing up the string portion before the hook portion is separated from the needle hole, the hook portion can be pulled out from the needle hole in a state where the upper thread is reliably hooked on the hook portion, and threading can be reliably performed.

According to the fourth invention, such excellent effects can be obtained: the operator can move the threading shaft up and down and rotate the threading shaft by moving the operation body up and down, and can perform the threading operation with one hand.

Drawings

Fig. 1 is a cross-sectional view on a surface including a needle bar in the left-right direction showing an arm structure of a sewing machine according to an embodiment of the present invention.

Fig. 2 is a sectional view for explaining the operation of the thread passing lever of the thread passing device of the sewing machine according to the embodiment of the present invention.

Fig. 3 is a three-side view (a plan view, a front view, and a side view) showing a structure of a thread guide member of a threading device of a sewing machine according to an embodiment of the present invention.

Fig. 4 is a two-side view (plan view and front view) showing the structure of a threading hook of a threading device of a sewing machine according to an embodiment of the present invention.

Fig. 5 is a perspective view showing an outline of a threading device of a sewing machine according to an embodiment of the present invention.

Fig. 6 is a schematic diagram illustrating an operation of the first camshaft moving in the first cam hole.

Fig. 7 is a front view, a schematic view, and a plan view illustrating an operation of the threading device of the sewing machine according to the embodiment of the present invention.

Fig. 8 is a front view, a schematic view, and a plan view illustrating an operation of the threading device of the sewing machine according to the embodiment of the present invention.

Fig. 9 is a front view, a schematic view, and a plan view illustrating an operation of the threading device of the sewing machine according to the embodiment of the present invention.

Description of the symbols

2: a first threading guide part; 3: a second threading guide part; 4: threading a bobbin; 5: a threading hook;

6: a wire guide member; 13: a needle bar arch seat; 14: a sewing needle; 14 a: a pinhole; 15: a needle bar;

17: an operation body; 20: a cam control member; 21: a first cam hole; 31: a second cam hole;

41: a first camshaft; 51: a first guide portion; 52: a hook portion; 61: a second guide portion;

62: a wire hanging part; 63: a second camshaft.

Detailed Description

The present invention will be described below with reference to the accompanying drawings showing embodiments thereof. In the following description, front, rear, left, and right as viewed from an operator who operates the sewing machine will be described as front, rear, left, and right. Fig. 1 is a cross-sectional view on a surface including a needle bar in the left-right direction showing an arm structure of a sewing machine according to an embodiment of the present invention. As shown in fig. 1, the arm portion of the sewing machine according to the present embodiment includes a needle bar support portion 1, a needle bar 15, a threading shaft 4 disposed close to the needle bar, and a first threading guide portion 2 and a second threading guide portion 3 which incorporate the threading shaft 4, are movable in the vertical direction, and are rotatable about the center axis of the threading shaft 4.

The up-and-down movement of the needle bar 15 is performed as follows. As shown in fig. 1, a thread take-up crank 11 of a thread take-up mechanism, not shown, is provided at a left end side portion of the main shaft 9, and a needle bar crank lever 12 is rotatably connected to the thread take-up crank 11 via a crank pin. A needle bar abutment 13 is connected to a substantially middle portion of the needle bar 15, and a needle bar crank lever 12 is connected to the needle bar abutment 13.

When sewing, the main shaft 9 is driven to rotate by a sewing machine motor; the needle bar 15 is driven to reciprocate up and down by the needle bar crank rod 12. The mechanism for driving the sewing needle 14 to swing by the needle bar support 1 using a stepping motor or the like is not particularly limited, and a general mechanism is sufficient, and therefore, a detailed description thereof will be omitted.

The threading hook 5 is provided at the lower end of the threading shaft 4 to be inserted through the needle hole 14a of the sewing needle 14. A thread guide member 6 is provided on the upper portion of the threading hook 5 via a compression spring 7 which urges the thread guide member 6 to push up the threading hook 5, and the thread guide member 6 is rotatable independently of the threading shaft 4 to guide the thread to the threading hook 5.

The positions of the threading hook 5 and the needle hole 14a of the sewing needle 14 can be adjusted to appropriate positions by the positioning plate (positioning member) 8. A needle bar supporting part 1 for supporting a needle bar 15 in a vertically movable manner is arranged on the head part of the arm part along the vertical direction, and the upper end part of the needle bar supporting part 1 is supported on a sewing machine frame in a swingable manner.

Further, the threading shaft 4 may be moved up and down in conjunction with the up and down movement of the needle bar 15, but the present invention is not limited to this, and for example, as shown in fig. 1, it is preferable to provide an operation mechanism 16 that can be operated by an operator with one hand. In the example shown in fig. 1, the operation mechanism 16 is composed of an operation body (operation lever) 17, a threading shaft connecting plate 18 connected to the threading shaft 4, and an operation body shaft 19, and moves the threading shaft 4 and the needle bar 15 up and down in conjunction with each other by moving the operation body 17 up and down. Thus, the operator can move the threading shaft 4 up and down and rotate by moving the operation body 17 up and down, and can perform the threading operation with one hand.

Next, a threading device for threading the upper thread through the needle hole 14a of the sewing needle 14 will be described. Fig. 2 is a sectional view for explaining the operation of the thread passing lever 4 of the thread passing device of the sewing machine according to the embodiment of the present invention. As shown in fig. 2, the thread passing lever 4 of the embodiment is connected to the first thread passing guide part 2 and the second thread passing guide part 3 by a cylindrical cam mechanism. The first thread guide portion 2 and the second thread guide portion 3 are fixed to the needle bar support 1 which moves up and down while approaching. In the present embodiment, the structure is such that: in order to reliably function the cylindrical cam mechanism, the thread guide portion is divided into two parts and each thread guide portion is screwed to the needle bar support portion 1 in order to more firmly fix the thread guide portion to the needle bar support portion 1. Of course, there is no particular problem in forming the threading guide portion as a single body without dividing it.

The thread passing lever 4 is provided so as to be insertable and fitted into the first cam hole 21 provided in the first thread passing guide portion 2, and a first cam shaft 41 protrudes from the peripheral surface. When the first thread guiding portion 2 and the second thread guiding portion 3 are lowered (raised) in conjunction with the lowering of the needle bar 15, the first cam shaft 41 moves along the first cam hole 21, and the threading hook 5 provided at the lower end of the threading rod 4 rotates clockwise (counterclockwise) as viewed from above (first rotation mechanism).

A second cam shaft (not shown) insertable and fitted into the second cam hole 31 provided in the second thread passing guide portion 3 is provided in the thread guide member 6 rotatably connected to the lower end portion of the thread passing lever 4. When the first thread passing guide portion 2 and the second thread passing guide portion 3 are lowered (raised) in conjunction with the lowering of the needle bar 15, the second cam shaft moves along the second cam hole 31, and the thread guide member 6 provided at the lower end of the thread passing lever 4 rotates in the direction opposite to the thread passing hook 5, that is, in the counterclockwise direction (clockwise direction) as viewed from above (second rotating mechanism). In this way, the threading hook 5 and the thread guide member 6 approach or separate in accordance with the vertical movement and rotation of one threading shaft 4, and the threading operation of the needle hole 14a can be controlled by only one threading shaft 4.

Fig. 3 is a three-side view (a plan view, a front view, and a side view) showing a structure of the thread guide 6 of the threading device of the sewing machine according to the embodiment of the present invention. Fig. 3(a) shows a plan view of the thread guide 6 of the threading device of the sewing machine according to the embodiment of the present invention, fig. 3(b) shows a front view, and fig. 3(c) shows a side view. The thread guide member 6 includes a second guide portion 61 that rotates about the threading shaft 4, and a thread hooking portion 62 that is bifurcated at an end of the second guide portion 61 so as not to interfere with the needle bar 15. The second guide portion 61 is provided with a second cam shaft 63 which is insertably fitted into the second cam hole 31 provided in the second threading guide portion 3. The second cam shaft 63 moves along the second cam hole 31, and the thread guide member 6 rotates counterclockwise (clockwise) as viewed from above the threading shaft 4. The thread hooking portion 62 is guided to the needle bar 15 in response to the rotation of the second guide portion 61 of the thread guide member 6, and the thread hooked by the thread hooking portion 62 is guided to the vicinity of the hook portion 52 (see fig. 4) of the threading hook 5.

Fig. 4 is a two-side view (front view and plan view) showing the structure of the threading hook 5 of the threading device of the sewing machine according to the embodiment of the present invention. Fig. 4(a) is a front view showing the structure of a threading hook 5 of a threading device of a sewing machine according to an embodiment of the present invention, and fig. 4(b) is a plan view. The first guide part 51 rotates around the threading shaft 4, and the hook 52 provided at the end of the first guide part 51 and used for hooking the thread. In response to the rotation of the first guide 51, the hook 52 comes out of or enters the needle hole 14a of the sewing needle 14, and the hook 52 threads the needle hole 14 a.

Fig. 5 is a perspective view showing an outline of a threading device of a sewing machine according to an embodiment of the present invention. Fig. 5 shows a state before threading, and in order to facilitate understanding of the structure of the thread threading lever 4, the distance between the thread threading lever 4 and the needle bar 15 is described to be larger than the actual distance.

When the operator lowers the operation body 17 with one hand, the thread passing lever 4 is lowered integrally with the needle bar 15. The needle bar 15 is lowered until the cam control member 20, which controls the action of the first cam shaft 41, comes into contact with the needle bar abutment 13. The first thread guiding part 2 and the second thread guiding part 3 are integrated with the thread passing shaft 4 and descend until the cam control part 20 contacts the needle bar arch 13 and the needle bar crank lever 12 is the lowest point by the needle bar arch 13 being pressed down. Accordingly, the threading hook 5 and the thread guide member 6 do not rotate.

When the cam control member 20 comes into contact with the needle bar abutment 13 and the needle bar crank pin 12 becomes the lowermost point, the needle bar 15 and the thread passing rod 4 are no longer lowered, and the first cam shaft 41 comes into contact with the end of the cam control member 20, so that the first cam shaft 41 moves along the upper edge portion of the first cam hole 21. In the present embodiment, the first cam shaft 41 operates as follows depending on the shape of the first cam hole 21.

Fig. 6 is a schematic diagram illustrating the operation of the first camshaft 41 moving in the first cam hole 21. As shown in fig. 6, the width in the vertical direction is larger than the shaft diameter of the first camshaft 41 in the vicinity of the uppermost portion of the first cam hole 21. Therefore, when the operating body 17 is raised from the lowest point, the time when the first cam shaft 41 starts to be raised can be delayed, and the operation can be controlled so that only the string hooking portion 62 of the string guiding member 6 is raised first and then the string threading hook 5 is disengaged from the needle hole 14 a. Therefore, the upper thread can be reliably hooked on the hook portion 52 of the threading hook 5 and then pulled out from the needle hole 14a, and the threading can be reliably performed.

The specific operation is as follows. When the cam control member 20 is in contact with the needle bar abutment 13 and the needle bar crank pin 12 is at the lowermost point, the first cam shaft 41 is positioned at the lowermost end of the first cam hole 21 in a state of being in contact with one end of the cam control member 20. When the operating body 17 is further lowered, the first cam shaft 41 moves along the movement locus 71, the threading shaft 4 does not rotate, and only the first threading guide 2 and the second threading guide 3 are further lowered. At this time, the second cam shaft 63 starts moving along the second cam hole 31, and the thread guide member 6 rotates counterclockwise as viewed from above, thereby starting moving in the direction of the needle bar 15. That is, since the first cam hole 21 and the second cam hole 31 are inclined in opposite directions, the threading hook 5 and the thread guide member 6 can be rotated in opposite directions to each other by one threading shaft 4.

When the operating body 17 is further lowered, the first cam shaft 41 moves along the movement locus 72, the threading shaft 4 rotates clockwise as viewed from above, and the threading hook 5 provided at the lower end moves toward the needle hole 14a and passes through. By the rotation of the threading shaft 4, the second cam shaft 63 further moves along the second cam hole 31 of the second threading guide 3. By further movement of the second cam shaft 63 along the second cam hole 31, the thread guide member 6 is further rotated counterclockwise as viewed from above and moved to a position to grip the needle bar 15.

By rotating the threading hook 5 and the thread guide member 6 in opposite directions to each other in this way, the upper thread hooked on the thread guide member 6 can be reliably guided to the threading hook 5, and threading can be reliably performed by pulling out the threading hook 5 hooking the upper thread from the needle hole 14 a.

In the present embodiment, the thread guide member 6 is further moved up and down by the compression spring 7 as the urging member in order to more reliably hook the upper thread on the threading hook 5. That is, the lengths of the first cam hole 21 and the second cam hole 31 are set so that the second cam shaft 63 reaches the lowermost point of the second cam hole 31 before the first cam shaft 41 reaches the uppermost point of the first cam hole 21, and the first cam shaft 41 is moved along the movement locus 73 when the operating body 17 is further lowered.

By doing so, after the second cam shaft 63 reaches the lowermost point of the second cam hole 31, the compression spring 7 is compressed, and only the wire guide member 6 further descends, and the operating body 17 reaches the lowermost point. Therefore, the thread guide member 6 finishes the rotational movement before the threading hook 5 passes through the needle hole 14a, and can be pushed down in advance downward compared with the position in the state where the hook portion 52 of the threading hook 5 passes through the needle hole 14 a.

When the operation body 17 starts to be raised, only the thread guide member 6 is raised by the elastic force of the compression spring 7, and the upper thread hooked on the thread guide member 6 is surely hooked on the hook portion 52 of the threading hook 5 passed through the needle hole 14 a. When the operating body 17 is further raised in this state, the first cam shaft 41 moves along the movement locus 74, the threading shaft 4 rotates counterclockwise as viewed from above, and the threading hook 5 provided at the lower end is disengaged from the needle hole 14 a. At this time, the thread hooked on the hook 52 passes through the needle hole 14a, and the threading is completed.

Fig. 7 to 9 are a front view, a schematic view, and a plan view illustrating an operation of the threading device of the sewing machine according to the embodiment of the present invention. Fig. 7(a) is a front view of an initial state and a schematic view showing a state of a cam, fig. 7(b) is a plan view showing a positional relationship between the threading hook 5 and the thread guide member 6 in the initial state, fig. 7(c) is a front view showing a state where the cam control member 20 is lowered and the needle bar crank lever 12 is at the lowermost point and a schematic view showing a state of the cam, fig. 7(d) is a plan view showing a positional relationship between the threading hook 5 and the thread guide member 6 in a state where the cam control member 20 is lowered and the needle bar crank lever 12 is at the lowermost point, fig. 7(e) is a front view showing a state where the first cam shaft 41 is raised along the movement trajectory 71 and a schematic view showing a state of the cam, and fig. 7(f) is a plan view showing a positional relationship between the threading hook 5 and the thread guide member 6 in a state where the first cam shaft 41 is raised along the movement trajectory 71.

From the position shown in fig. 7(a), when the operator lowers the operation body 17 with one hand, the thread passing lever 4 and the needle bar 15 are lowered integrally, and the thread passing lever 4 is lowered until the cam control member 20 for controlling the operation of the first cam shaft 41 comes into contact with the needle bar abutment 13 and the needle bar crank lever 12 is at the lowermost point as shown in fig. 7 (c). Since the threading hook 5 and the thread guide member 6 do not rotate until the cam control member 20 comes into contact with the needle bar abutment 13 and the needle bar crank lever 12 reaches the lowermost point, the positional relationship between the threading hook 5 and the thread guide member 6 is not changed as shown in fig. 7(b) and (d).

The operating body 17 is further lowered from the position shown in fig. 7(c), and when the position shown in fig. 7(e), that is, the first cam shaft 41 reaches the upper edge portion of the first cam hole 21, only the first thread passing guide 2 and the second thread passing guide 3 are further lowered without rotating the thread passing shaft 4. Therefore, the threading hook 5 does not rotate and does not move from the position shown in fig. 7(b) and (d). On the other hand, the second cam shaft 63 starts moving along the second cam hole 31, and as shown in fig. 7(f), the thread guide member 6 rotates counterclockwise as viewed from above, thereby starting moving in the direction of the needle bar 15.

Fig. 8(a) is a front view showing a state before the threading hook 5 passes through the needle hole 14a and a schematic view showing a cam state, fig. 8(b) is a plan view showing a positional relationship between the threading hook 5 and the thread guide member 6 before the threading hook 5 passes through the needle hole 14a, fig. 8(c) is a front view showing a state where the operation body 17 is at the lowermost point and a schematic view showing a cam state, fig. 8(d) is a plan view showing a positional relationship between the threading hook 5 and the thread guide member 6 when the operation body 17 is at the lowermost point, fig. 8(e) is a front view at the end of threading and a schematic view showing a cam state, and fig. 8(f) is a plan view showing a positional relationship between the threading hook 5 and the thread guide member 6 at the end of threading.

As shown in fig. 8(a), when the operating body 17 is further lowered, the first cam shaft 41 moves along the upper edge portion of the first cam hole 21, and the threading shaft 4 rotates clockwise as viewed from above. The first thread guide portion 2 and the second thread guide portion 3 are also further lowered. Accordingly, as shown in fig. 8(b), the threading hook 5 rotates toward the needle hole 14 a. On the other hand, the second cam shaft 63 continues to move along the second cam hole 31, and as shown in fig. 8(c), in a state where the operating body 17 is at the lowermost point, the hanging portion 62 of the thread guide member 6 is pressed down directly below the hook portion 52 in a state where the hook portion 52 of the threading hook 5 passes through the needle hole 14 a.

That is, the lengths of the first cam hole 21 and the second cam hole 31 are set so that the second cam shaft 63 reaches the lowermost point of the second cam hole 31 before the first cam shaft 41 reaches the uppermost point of the first cam hole 21, and when the operating body 17 is lowered, the first cam shaft 41 is moved along the movement locus 73. By doing so, after the second cam shaft 63 reaches the lowermost point of the second cam hole 31, the compression spring 7 is compressed, and only the wire guide member 6 further descends, and the operating body 17 reaches the lowermost point. By adjusting the length, inclination, and the like of the cam hole in this way, the operation time of the hook portion 52 of the threading hook 5 and the thread hooking portion 62 of the thread guide member 6 can be adjusted, and threading can be performed more reliably.

Therefore, before the threading hook 5 passes through the needle hole 14a, the thread guide member 6 finishes the rotational movement, and in a state where the operating body 17 is at the lowermost point, the thread guide member 6 is pressed downward from the position where the hook portion 52 of the threading hook 5 has passed through the needle hole 14 a. In this state, since the compression spring 7 is pressed down, the wire guide member 6 is pushed up by the elastic force of the compression spring 7 in a state where the operator is away from the operation body 17. As a result, as shown in fig. 8(e) and (f), only the thread guide member 6 is lifted without changing the horizontal positional relationship between the threading hook 5 and the thread guide member 6. Thus, the needle thread hooked on the thread hooking portion 62 is raised to the hook portion 52 of the threading hook 5, and is reliably locked to the hook portion 52.

Fig. 9(a) is a front view showing a state where the threading hook 5 is separated from the needle hole 14a and a schematic view showing a cam state, fig. 9(b) is a plan view showing a positional relationship between the threading hook 5 and the thread guide member 6 in a state where the threading hook 5 is separated from the needle hole 14a, fig. 9(c) is a front view showing a state where the cam control member 20 is in contact with the needle bar abutment 13 and a schematic view showing a cam state, fig. 9(d) is a plan view showing a positional relationship between the threading hook 5 and the thread guide member 6 in a state where the cam control member 20 is in contact with the needle bar abutment 13, fig. 9(e) is a front view showing an initial state and a schematic view showing a cam state, and fig. 9(f) is a plan view showing a positional relationship between the threading hook 5 and the thread guide member 6 in an initial state.

As shown in fig. 9(a), as the operating body 17 is raised, the threading hook 5 with the upper thread hooked on the hook portion 52 is disengaged from the needle hole 14a as shown in fig. 9 (b). Then, the needle thread is threaded through the needle hole 14 a.

When the operating body 17 is further raised, the first cam shaft 41 moves along the movement locus 74, that is, along the lower edge portion of the first cam hole 21, and the cam control member 20 returns to the state of contacting the needle bar abutment 13 as shown in fig. 9 (c). As the first cam shaft 41 moves along the upper edge portion of the first cam hole 21, the threading shaft 4 rotates counterclockwise as viewed from above. On the other hand, the second cam shaft 63 continues to move along the second cam hole 31, and the wire guide member 6 rotates clockwise as viewed from above, as shown in fig. 9 (d).

When the operating body 17 is further raised, the first cam shaft 41 returns to the lowermost end of the first cam hole 21, and the needle bar 15 and the threading shaft 4 are also raised. The second cam shaft 63 continues to move along the second cam hole 31, and as shown in fig. 9(f), the wire guide member 6 rotates clockwise as viewed from above and returns to the original position.

As described above, according to the present embodiment, since the inclination directions of the two cam holes are opposite to each other, the threading hook 5 and the thread guide member 6 can be rotated in opposite directions by one threading shaft 4, the head can be made compact as a whole, and the number of components can be reduced to reduce the cost. Further, even when sewing requiring a delicate operation, since the inertia of the moving portion is small, it is not necessary to reduce the sewing speed in order to maintain the sewing accuracy.

In addition, various modifications may be made to the above-described embodiments without departing from the scope of the main subject matter of the present invention.

Claims (2)

1. A threading device of a sewing machine is provided with:

a thread passing shaft which is close to a needle rod for moving the supported sewing needle up and down, can move up and down and is supported in a manner of rotating around the shaft;

a threading hook fixed to a lower end of the threading shaft and having a hook portion capable of passing through a needle hole of a sewing needle and a first guide portion for guiding the hook portion to the needle hole;

a positioning member for limiting a descending critical position of the thread passing shaft to a position where the hook portion and a needle hole of the sewing needle are consistent in height;

a first rotating mechanism which rotates the first guide part by a predetermined angle near a descending critical point of the thread passing shaft so that the hook part passes through a needle hole of the sewing needle; and the number of the first and second groups,

a thread guide member for guiding the upper thread to the hook part near the descending critical point of the thread passing shaft,

it is characterized in that the preparation method is characterized in that,

the thread guide member has a thread hooking portion for hooking the thread and a second guide portion for guiding the thread hooking portion in a direction of the sewing needle,

a second rotating mechanism which rotates the second guide part by a predetermined angle near a descending critical point of the thread passing shaft so that the thread hanging part crosses the sewing needle and crosses the sewing needle,

the first and second rotating mechanisms rotate the threading hook and the thread guide member in opposite directions to each other,

comprises a threading guide member which is fitted to the thread passing shaft and fixed to the sewing machine body, and has a first cam hole and a second cam hole on the peripheral surface,

the first rotation mechanism includes the first cam hole and a first cam shaft provided on the threading shaft and fitted in the first cam hole,

the second rotating mechanism includes the second cam hole and a second cam shaft provided in the wire guide member and fitted in the second cam hole,

the inclination direction of the first cam hole and the inclination direction of the second cam hole are opposite to each other,

the width of the first cam hole in the vertical direction near the uppermost portion is larger than the shaft diameter of the first camshaft,

the thread guide member is provided with a biasing member for biasing the thread hook and the thread guide member apart from each other.

2. The threading device of a sewing machine according to claim 1,

the thread threading device is provided with an operation body which can move up and down and operates the thread threading shaft.