JPH0475687A - Cloth feed mechanism of sewing machine - Google Patents

Abstract

PURPOSE:To reduce a difference of the feed amount between the forward feed and the backward feed by setting engaging areas of a driven gear engaged to a driving gear in the forward feed and the backward feed to each different area, and also, changing the pitch circle center position of the driven gear of an oscillating arm against a supporting shaft. CONSTITUTION:In a forward/backward feeding mechanism 1, a driven gear 13A provided on an oscillating arm 17 is engaged to a driving gear 11A rotated by a cloth feeding motor, a rotation of the cloth feed motor 11 is transferred to the oscillating arm 17 through both the gears, and the oscillating arm 17 oscillates centering around a supporting shaft 15 and allows feed dog H to move in the forward and the backward directions. Also, in the forward feed and the backward feed of working cloth, engaging areas of the driven gears 13A engaged to the driving gear 11A exist in each different area, and also, by a pitch circle center position changing means, the position of the pitch circle center PC of the driven sear 13A is changed against the supporting shaft 15 which becomes the center of oscillation. Therefore, when the supporting shaft and the position of the pitch circle center PC are equal, backlashes of both the gears in the forward feed and the backward feed are equal, and when the supporting shaft 15 and the position of the pitch circle center PC are different, the backlashes of both the gears are different in the forward feed and the backward feed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cloth feeding mechanism for a sewing machine, and more specifically, a cloth feeding motor that is different from the drive motor that drives the main shaft moves the workpiece cloth forward and backward. This invention relates to a fabric feeding mechanism of a sewing machine that moves the fabric backward.

[Prior Art] Conventionally, a cloth feeding mechanism has been known in which a cloth feeding motor provided separately from a main shaft drive motor is driven to transport a workpiece cloth forward and backward. This mechanism includes a back-and-forth drive mechanism that moves a feed table on which feed teeth are formed for transferring the work cloth in the front-rear direction, and a vertical drive mechanism that moves the feed table in the up-down direction. As shown in FIG. 5 (schematic view of the inside side of the sewing machine bed), the fabric feed motor (pulse motor) P rotates forward and backward at a predetermined angle, and the driven gear P3 meshes with the drive gear P2 of the fabric feed motor P. A swinging arm P5 that can swing in the direction of arrow a about a support shaft P4, a connecting shaft P6 provided on the free end side of the swinging arm P5, and a free end that is rotatably supported by the connecting shaft P6. It consists of a horizontal feed arm P8 slidably supported on a horizontal support surface P7.

A guide shaft P9 is vertically provided on both the upper and lower sides of the horizontal feed arm P8, and this guide shaft P9 is connected to the feed table PI.
O (with a feed dog P] formed at the top) so as to be vertically movable. Therefore, the forward and reverse rotational force of the cloth feed motor P1 is applied to the drive gear P2. When the signal is transmitted to the swing arm P5 via the driven gear P3 and the swing arm P5 swings, the horizontal feed arm P8 supported by the connecting shaft P6 moves in the direction indicated by the arrow (back and forth), and the feed base PIO moves as a guide. It is driven in the front-back direction via the shaft P9.

On the other hand, the vertical drive mechanism moves the arrow C to the feed table PIO by the rotation of the eccentric cam P12 that rotates in synchronization with the main shaft (path shown in the figure).
directional motion is applied to move the feed table PIO up and down along the guide shaft P9.

The workpiece cloth is transferred by applying a combination of such vertical and one-frontal movements to the feed table PIO.

[Problem to be solved by the invention] However, due to variations in the rotational angle accuracy of the cloth feed motor, mechanical parts machining accuracy, assembly accuracy, etc., and the influence of load inertia, it is difficult to perform machining using forward feed and backward feed (back feed). There were cases where a difference occurred in the amount of cloth fed.As a result, the fabric feeding mechanism of the sewing machine of the present invention It is an object of the present invention to solve the above problems and reduce the difference in feed amount between forward feed and backward feed.

[Means for Solving the Problems] The cloth feeding mechanism of the sewing machine of the present invention includes: a feed dog that transfers the work cloth; a back and forth feed mechanism that imparts back and forth movement to the feed dog; and the above-mentioned. In the fabric feeding mechanism of a sewing machine that is equipped with a vertical drive mechanism that imparts vertical movement to the feed dog and that intermittently transports the workpiece cloth forward and backward, The oscillator has a feed motor and a driven gear that meshes with a drive gear rotated by the cloth feed motor, and is oscillated about a predetermined support shaft, and the oscillation causes the feed dog to move in the front and back direction. and a pitch circle center position changing means for changing the pitch circle center position of the driven gear of the swing arm with respect to the support shaft, the pitch circle center position changing means meshing with the drive gear during forward feeding and backward feeding of the work cloth. The gist is that the meshing areas of the driven gears are in different areas.

[Function] The fabric feed mechanism of the sewing machine of the present invention having the above configuration (the feed dog is given back and forth movement by the back and forth feed mechanism, and the work cloth is intermittently moved by the up and down drive mechanism) Transfer forward and backward.With this forward and backward feeding mechanism (
A driven gear provided on the swinging arm meshes with the drive gear rotated by the front cloth feeding motor, and the rotation of the cloth feeding motor is transmitted to the swinging arm via both gears, and the two swinging arms are rotated. It swings around the support shaft to move the feed dog back and forth.

The meshing areas of the driven gear that meshes with the drive gear are in different areas when the work cloth is fed forward and backward, and the position of the pitch circle center of the driven gear is changed by the pitch circle center position changing means. Therefore, if the positions of the support shaft and the center of the pitch circle are the same, the pack lash of both gears during forward feed and backward feed will be equal, and the position of the support shaft and pitch circle If the center position is different (fS
The backlash of both gears differs between forward feed and backward feed. Since the feed amount depends on backlash, if there is a difference in the feed amount between forward feed and backward feed (by changing the center position of the pitch circle relative to the support shaft, By adjusting the backlash of the gears, the difference in feed amount is reduced.

[Embodiment] An embodiment of the cloth feeding mechanism of the sewing machine of the present invention will be described below.

As shown in the perspective view of FIG. 1, the cloth feeding mechanism of the sewing machine of the embodiment includes a back and forth drive mechanism 1 that moves a feed table to which a feed dog H is fixed in the front and rear directions, and a back and forth drive mechanism 1 that moves the feed table in the vertical direction. It is provided with a vertical drive mechanism 3 that moves. Additionally, a pitch circle center position changing mechanism shown in FIG. 2 is provided. Furthermore, an electronic control device 5 shown in the block diagram of FIG. 4 is provided.

As shown in FIG. 1, the longitudinal drive mechanism includes a pulse motor, a swing lever 13, a support shaft 15, a swing arm 7, a connecting shaft 9, a horizontal feed arm 21, a feed arm support 23, etc. Consisting of In addition, in the figure, the rotary hook K is shown by a dashed dotted line to facilitate understanding of the arrangement of these components.

The pulse motor] 1 is independent from the drive system of the lower shaft S (main shaft drive system) that is linked to the vertical movement of the sewing machine needle, and is synchronized with the lower shaft S by the electronic control device 5 (Fig. 2), which will be described later. The drive is controlled by A drive gear 11A is fixed to the soil force shaft. A light shielding plate]°]B is attached to the drive gear]1A. Further, - the photointerrupter 25 is connected to the light shielding plate 11B.
is installed at a location where it passes.

Swinging lever 13 (It is a plate material having two levers bent in an oval shape. A support shaft 15 is inserted through the bent portion, and the swinging lever 13 is supported by the support shaft) 5 so as to be swingable. A driven gear 13A that meshes with the drive gear 11A is attached to the tip of the lever that extends toward the front (towards the front of the drawing).
can be installed.

On the other hand, the side surface of the swinging arm 17 is fixed to a lever extending upward from the bent portion.

The side view of FIG. 2(A) shows the pitch circle center position changing mechanism as its fixing structure.

As shown in the figure, the swing lever 13 has 13 elongated holes 14C, 148.14C in the lower center of the upper plate.

Upper elongated hole 14A [i Connection shaft 1 passing through swing arm 17
It has an outer diameter of 9, a width (minor axis) between the paths, and a length (long axis) larger than the diameter. The lower elongated hole 14C is connected to the swing arm 17.
The width (minor axis) between the diameter and the width of the support shaft 15 passing through the passageway (short axis) is larger than the outer diameter (long axis). Moreover, the elongated hole 14B in the center has a vertical (long axis) larger than the outer diameter of the screw 16 that fixes the swinging lever 13 to the swinging arm 7. In other words, the swinging lever 3 is a connecting shaft] 9 and the spindle] 5,
The swinging arm 17 is movable in the vertical direction.

This movement (the center of the pitch circle of the driven gear 13A is the support shaft)
As a result, the swinging arm 17 is deviated from the axis of the swing arm 17 in the vertical direction. An explanatory diagram is shown in FIG. Driven gear 1 as shown
The center PC of the pitch circle P13A of 3A is shifted from the axis (rotation center) RC of the support shaft]5.

The pitch circle center position changing mechanism of the embodiment further has a configuration for finely adjusting the amount of deviation between the pitch circle center PC and the axis RC of the support shaft 15. FIG. 2(B) shows a rear view of the fine adjustment mechanism. As shown in the figure, a male screw member 18 is rotatably supported in the vertical direction by a support member 18A on the swing arm]7. The swing lever] 3 has a threaded ply plate 13B into which the thread of the male threaded member 18 is threaded. Therefore, the male threaded member 18
By rotating the swing lever]
3 rises and falls in the vertical direction of the swinging arm 17.

In this way, the amount of deviation between the pitch circle center PC of the driven gear 13A and the axis RC of the support shaft 5 is finely adjusted.

Next, the swing arm 17, the horizontal feed arm 21, and the feed arm support section 23 will be explained.

The swinging arm 17 (which is a roughly H-shaped member. Bearing portions 17A are formed at the lower part of the vertical axis on both sides of the swinging arm 17, through which the support shaft 15 is inserted. In this way, the swinging lever] 3 is integrally supported by the support shaft 15 in a freely swinging manner.
It is suspended above a base (not shown) with a slight gap.

On the other hand, bearing portions 17B are formed on each of the upper portions of the vertical axis on both sides of the swing arm]7. A rack (connection shaft) 9 is passed between each bearing portion 17B.

A horizontal feed arm 21 (which is a thick plate material having a substantially triangular shape. A roller 2] A (supported part) is provided on the side surface of the front end corresponding to the apex of the triangle. The bottom side of the triangle is supported by the connecting shaft 19. There are bearing parts 21B and 2-IC on both sides of the rear end corresponding to
Equipped with A connecting shaft]9 passes through the bearing portion 21B. The penetrating connecting shaft 19 is inserted halfway into the bearing portion 21C. In this way, the horizontal feed arm 21 is rotatably supported by the connection shaft ]9.

In addition, a tension spring 27 is tensioned between the side surface of the horizontal feed arm 21 and the lower frame F.
A is always placed on the surface 23A of the feed arm support section 23, which will be described later.
bring them close together.

Further, a guide rod 29 is fixed to the rear bearing portion 21C in a state that it passes through the bearing portion 21C. The axis of the guide rod 29,
It intersects the plate surface of the horizontal feed arm 21 perpendicularly. The upper part of the guide rod 29 penetrates the feed bar body,
The portion that protrudes from the lower part penetrates the guide portion D1 extending below the feed bar. That is, the feed base is the guide rod 29
is supported so as to be movable in the vertical direction on the plate surface of the horizontal feed arm 2].

Feed arm support part 23 (screwed to upper frame F).

The shape of the surface 23A on which the roller 21A slides (formed in an arc shape in the upper and rearward direction. In the embodiment, the sum of the radius of curvature of the surface 23A and the radius of the roller 21A is the diameter of the support shaft 1.
5 and the connecting shaft 19 are designed to have the same center-to-center distance.

The above-mentioned horizontal feed arm 2 is rotatably supported by the connecting shaft 19 and slidably supported by the surface 23A, so that the rack is passed horizontally.

The operation of the above-mentioned longitudinal drive mechanism 1 will be briefly explained.

As shown in FIG. 1, when the pulse motor 11 rotates in forward and reverse directions and its driving gear IIA sends the driven gear 13A in the vertical direction, the swinging lever 3 swings about the support shaft 15. move. Then, the swing arm 17, which is integrally fixed to the swing lever 13, similarly swings about the support shaft]5.

This swinging of the swinging arm 17 causes the connecting shaft] 9 to reciprocate in the front-rear direction. The horizontal feed arm 21, which is suspended between the connection shaft 19 and the feed arm support portion 23, reciprocates in the front and back direction along the connection shaft]9. Surface 23 of feeding arm support section 23
Since A is formed in the shape of a circular arc with a predetermined radius of curvature, the horizontal feed arm 2 reciprocates back and forth while maintaining its horizontal position. Then, the rear guide rod 29 pulls the feed bar in the front-rear direction, and moves the feed dog H in the front-rear direction.

Next, the vertical drive mechanism 3 will be explained.

The vertical drive mechanism 3 (as shown in FIG. 1) consists of a lower shaft S, an eccentric cam 31, a vertical movement lever 33, etc.

The lower shaft S has a timing belt attached to pulley S1,
It is rotated in synchronization with an upper shaft (not shown) for vertical movement of the sewing machine needle.

The eccentric cam 31 is a cam that is eccentrically provided on the lower shaft S. The amount of eccentricity is determined corresponding to the vertical movement stroke of the feed dog H.

The vertically movable lever 33 has its front end swingably supported by the rod 33A, and its lower abdominal surface abuts against the eccentric cam 3.

A roller 35 is rotatably supported on the side surface of the rear end of the vertically movable bar 33. A support surface 37 provided on the lower surface of the feed platform is in sliding contact with the roller 35. On the - side, a compression spring 39 is disposed between the guide portion D1 of the feed platform and the horizontal feed arm 21, and the feed platform is biased downward. With the above configuration, the support surface 37 is always in close contact with the roller 35, and the vertically moving lever 33 is always in close contact with the eccentric cam 3. Therefore, the roller 35 accurately moves up and down in accordance with the shape of the eccentric cam 31, and the feed bar also moves up and down in accordance with the shape of the eccentric cam 31.

Next, the electronic control device 5 that controls the above-mentioned mechanism will be explained based on FIG. 4. The electronic control unit 5 is an arithmetic and logic operation circuit including a well-known CPU 51, ROM 53, RAM 55, input/output interfaces 57, 59, and the like.

The input interface 57 includes an operation switch 6 for power supply, etc.
1 and a photointerrupter 25 are connected. A drive circuit 65 for a main shaft motor 63 that rotates the lower shaft S (main shaft S) is connected to the output interface 59. Also, a drive circuit 67 for a pulse motor of the longitudinal drive mechanism 1 is connected.

The cloth feeding device of the sewing machine described above operates as follows. When the power is turned on, the electronic control unit 5 uses the on/off signal of the photointerrupter 25 to determine the origin of the phase of the drive gear 1]A of the pulse motor. That is,
In the example shown in FIG. 1, the engagement between the drive gear IIA and the driven gear 13A is located at the center of the driven gear 13A.

Find the origin of the phase and move the second engagement to the upper end M1 of the area indicated by arrow M (the engagement area of forward feed) using the signal from the photointerrupter 25.
7 is tilted furthest toward the front, the connecting shaft 19 is moved furthest forward, and the feed dog H is arranged at the frontmost end of the square hole of the throat plate (not shown) (on the near side of the operator).

Thereafter, sewing is performed by a known method in accordance with the operation of the operation switch. For example, feed pitch data indicating the amount of work cloth to be transferred (feed pitch) for each stitch is read from the sewing data of a predetermined pattern. Then, the pulse motor 1 is rotated in synchronization with the rotation of the lower shaft S by a rotation angle determined from this feed pitch data, that is, a rotation angle corresponding to obtaining the feed pitch specified by the data.

At this time, even if the feed pitch data is data indicating forward feed (the crowned driving gear 11A is rotated from the upper end M1 of the engagement area indicated by the arrow M as described above), the driven gear 13A is rotated upward by an amount corresponding to the rotation angle. The swing lever 13 rotates upward.Thereafter, it moves back in synchronization with the timing of the rotation of the lower shaft S.

As a result of these rotations and back movements being repeated, the connecting shaft 19.
Via the horizontal feed arm 21 and the like, the feed dog H reciprocates in the front and rear directions at the front part of a square hole (not shown). By combining this reciprocating movement in the front-rear direction and the vertical movement by the vertical drive mechanism 3, the feed dog H moves in a trajectory indicated by arrow 1. This movement is performed at the front part of the square hole (not shown), so when feeding the workpiece fabric from the front side of the operator to a distant place during forward feeding, the feed dog H is attached to the edge of the fabric at the start of sewing.
Most of them bite, which is advantageous for feeding.

On the other hand, if the feed pitch data is backward feed data (the rotation of the pulse motor 11 of the cloth, the drive gear)]
A and the driven gear 13A are engaged in the area indicated by the arrow U (
The pulse motor 1] is controlled so as to be located at the lower end U1 of the meshing region for backward feeding, that is, so that the feed dog H is located at the rearmost end (farthest from the operator) of a square hole (not shown). Then, similarly to the forward feed, the drive gear 1]A is rotated from the lower end U] of the engagement area indicated by the arrow U, and the drive gear 1]A is rotated by a predetermined rotation angle (
The driven gear 13A is sent downward by a rotation angle determined from the feed pitch data by the drive gear IIA of the pulse motor, and the swing lever 13 is rotated downward. later,
The return movement is made in accordance with the timing of the rotation of the lower shaft S.

As a result of such rotation and back movement, the connecting shaft]9. Horizontal feed arm 2
A feed dog H reciprocates in the front and back direction through the first and second parts at the rear of a square hole (not shown). This back and forth reciprocating motion,
In combination with the vertical movement by the vertical drive mechanism 3, the feed dog H moves in a trajectory shown by arrow 2. This movement is performed at the rear of the square hole (not shown), so when feeding the workpiece fabric from far away to the operator in the backward feed mode, most of the feed dog H engages with the right end at the start of sewing, causing the feed to stop. It is advantageous for

Next, the operation of the pitch circle center position changing mechanism (hereinafter simply referred to as changing mechanism) will be explained.

As mentioned above, this is a mechanism for finely adjusting the positional relationship between the pitch circle center PC and the shaft center RC of the support shaft 15 (hereinafter referred to as the support shaft center RC). When adjusting the external threaded member 18 of the mechanism and shifting the swing lever] 3 upward with respect to the spindle 15, that is, when the pitch circle center PC is shifted upward with respect to the spindle center RC, the driven gear 13A and drive gear] Each pitch circle P13A with 1A
, P11A.

When in forward feed (front drive gear), move 1A to arrow M in Figure 1.
From the upper end M1 of the meshing region of FIG. When the circle center PC is shifted upward with respect to the spindle center RC, the backlash between the drive gear 13A and the driven gear 13A differs between forward transport and reverse transport. In Figure 3 (A)), the pitch circle PIIA of drive gear 1] A and the pitch circle P13A of driven gear 13A (compared to when forward feeding (Figure 3 (B)))
Since the two are separated from each other, backlash increases. Further, as the distance between the pitch circle center PC and the support shaft center RC increases, the difference in backlash between forward feeding and backward feeding increases.

This change in backlash affects the transfer amount (feed pitch) of the work cloth, as shown below.

Since the pulse motor 11 repeats forward and reverse rotation, if the backlash is large, the drive gear]1
Since the rotational direction side of A is not in contact with the driven gear 13A, the rotation of the drive gear IIA is not instantaneously transmitted. That is,
The rotation of the drive gear A is transmitted only when the drive gear A comes into contact with the driven gear 13A. Therefore, a swing corresponding to the rotation angle of the pulse motor 11 cannot be obtained, and the amount of movement of the feed dog H in the front-rear direction decreases, resulting in a decrease in the feed pitch. Further, the larger the backlash, the smaller the feed pitch is from 1.

As a result, when the pitch circle center PC is shifted upward with respect to the spindle center RC, the feed pitch for backward feeding becomes smaller than that for forward feeding. Conversely, when the pitch circle center PC is shifted downward with respect to the spindle center RC, the feed pitch of forward feed becomes smaller than that of backward feed. Further, the difference in the feed pitch between forward feed and backward feed is adjusted depending on the distance between the pitch circle center PC and the support shaft center RC.

Therefore, if there is a difference in the feed pitch between forward feed and backward feed due to variations in assembly accuracy, etc., or the influence of load inertia, etc., change the target. By adjusting the external threaded member of the mechanism] 8 and shifting the pitch circle center PC from the spindle center RC, it is possible to absorb the difference in the feed pitch between the two. As a result, the difference in feeding pitch between forward feeding and backward feeding can be reduced. This is particularly effective when sewing large patterns in which many differences in feed pitches are accumulated.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention.

Effect of slumber As detailed above, according to the fabric feeding mechanism of the sewing machine of the present invention, the meshing areas of the driven gear that meshes with the drive gear for forward feeding and backward feeding are made into separate areas, and 1: By changing the center position of the pitch circle of the driven gear of the swinging arm relative to the support shaft, the pack lash of both gears can be adjusted separately for forward feed and backward feed, and the feed amount for forward feed and backward feed can be adjusted. This has an extremely excellent effect of reducing the difference.

[Brief explanation of drawings]

Figure 1 is a perspective view of the fabric feeding mechanism of the sewing machine, Figure 2 (A) is a side view of the pitch circle center position changing mechanism, Figure 2 (B) is a rear view of the pitch circle center position changing mechanism, and Figure 3 is A), (B
) is an explanatory diagram showing the change in backlash due to deviation of the center of the pitch circle, FIG. 4 is a block diagram of the electronic control device, and FIG. 5 is an explanatory diagram illustrating the conventional mechanism. ]... - Front-rear drive mechanism 5... Electronic control device 1A... Drive gear 3A... Followed gears 4A, 14B. 5... Support shaft 7... Rocking arm 19... Connection shaft 3... Vertical drive mechanism 11... Pulse motor] 3... Rocking lever 14C... Long hole] 6...・Screw] 8...Male thread member H...Feed dog

Claims (1)

[Scope of Claims] 1. A feed dog that transports the work cloth, a back-and-forth feed mechanism that gives the feed dog a longitudinal movement, and a vertical drive mechanism that gives the feed dog a vertical movement, In a cloth feeding mechanism of a sewing machine that intermittently transports workpiece cloth forward and backward, the forward and backward feeding mechanism meshes with a cloth feeding motor that is different from the main shaft motor of the sewing machine and a drive gear rotated by the cloth feeding motor. A swinging arm having a driven gear and swinging around a predetermined support shaft and causing the feed dog to move forward and backward by the swing, and a pitch of the driven gear of the swinging arm with respect to the support shaft. pitch circle center position changing means for changing the center position of the circle, and the meshing area of the driven gear that meshes with the driving gear is in different areas when the work cloth is fed forward and when the work cloth is fed backward. Cloth feed mechanism of sewing machine.