JPS6345252Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field This invention relates to a buttonhole sewing machine that can perform tacking stitches.

Conventional technology Conventionally, a sewing machine that was able to perform tacking stitches at the end of buttonhole sewing (Japanese Patent Laid-Open No. 57-64086)
is proposed. In this sewing machine, as shown in Fig. 1a, following the completion of overstitching a buttonhole, for example, as shown in Fig. 1b, a tacking stitch is applied to the right end needle entry part of the right overlocking area H4. I was trying to make it happen. However, Fig. 1c
As shown in the figure, the left and right ends of the overlock stitch tend to turn inward due to the tightness of the thread.
When the tacking stitch was applied to the right end needle drop position of the overseam stitch, the space between the overseam stitch and the tacking stitch was widened, resulting in an unfavorable appearance. This result is more pronounced as the cloth becomes thinner.

Purpose of the invention The purpose of this invention is to eliminate the above-mentioned deficiencies in conventional buttonhole sewing machines.

Embodiment Hereinafter, an embodiment embodying this invention will be described based on the drawings from FIG. 2 onwards. A first cam wheel 12 is supported on a cam shaft 11 supported by a sewing machine frame (not shown).
A zigzag basic cam 13 made of a concave and convex cam is formed on the outer periphery of the cam 2 . Also, the camshaft 11
A second camshaft 14 is supported on the second camshaft 14, and a first control cam 15 is formed on the outer periphery of the second camshaft 14. This first
The control cam 15 is in phase with the zigzag basic cam 13 and has an uneven cam surface 15a consisting of five peaks and five valleys, and a flat cam surface 15b having an intermediate height between the valleys and the peaks. and an uneven cam surface 15a
A cam surface 15d for tacking is formed and has a height between the peak of and the flat cam surface 15b. Furthermore, in this embodiment, the third valley from the left in FIG. 3 is a flat cam surface 15c for regulating the needle swinging momentum, which will be described later. Second cam wheel 14
An annular second control cam 16 having a groove shape is provided on the side surface of the
The control cam 16 is made up of a small radius part 16a, a large radius part 16b, and long and short inclined parts 16c and 16d located between them, respectively.

A support shaft 17 is fixed to the sewing machine frame so as to be parallel to the camshaft 11.
A swing frame 18 is supported at 7 so as to be swingable only. A contact 19 is swingably attached to the support shaft 17 within the swing frame 18 . A connecting shaft 20 is attached to the swing frame 18, and the contact 19 is inserted into the connecting shaft 20.
The swing frame 18 and the contact 19 are designed to swing integrally. The contactor 19 is formed with a contact portion that can engage with the first control cam 15 . The swing frame 18 is connected via a link 21 to a swing link 33, a part of which is shown in FIG. 6, and the swing link 33 is connected to a needle bar support frame (not shown). When the swing frame 18 and the contact 19 swing around the support shaft 17, the needle bar support frame swings left and right.

Further, a clutch means (not shown) is provided on the camshaft 11, and the clutch means is operated to rotate or stop the second cam wheel 14 in synchronization with the rotation of the main shaft of the sewing machine. be done.

The auxiliary contact 22, which faces the zigzag basic cam 13 at one end, is rotatably supported on the sewing machine frame by a step screw 23, and is always engaged with the zigzag basic cam 13 by the action of a coil spring (not shown).
A switching lever 24 is rotatably supported at an intermediate portion of the step screw 23, and a pin 25 provided at one end of the switching lever 24 is fitted into the control cam 16. At the other end of the switching lever 24, a connecting lever 27 is rotatably supported at its intermediate portion by a shaft 26, and a pin 28 fixed to one end of the connecting lever 27 is connected to a slot 2 formed at the other end of the auxiliary contact 22.
9 is fitted. A first contact surface 30 located on the rotation start point side and a second contact surface 31 located on the tip end side are continuously formed on the side edge of the other end of the connection lever 27, and the contactor 19 A contact pin 32 provided at the tip of can engage with them. This connecting lever 27 and the auxiliary contact 22 constitute a connecting member for transmitting the movement according to the zigzag basic cam 13 to the contact 19.

The details of the mechanism related to the clutch means and buttonhole sewing are disclosed in Japanese Patent Application Laid-Open No.
It is described in Publication No. 57-64086.

Next, the operation of the buttonhole sewing machine configured as described above will be explained. Now, FIG. 3 shows the state immediately after the start of buttonhole sewing. In this state, the contact portion 1 of the contactor 19
9a engages with the first valley of the uneven cam surface 15a of the first control cam 15, and the switching lever 24
The pin 25 is connected to the large radius portion 16 of the second control cam 16.
b, and the switching lever 24 is rotated to a predetermined position. Therefore, the connecting lever 24 is rotated and placed in one control position, and the first contact surface 30 on one side edge of the connecting lever 27 faces the contact portion 19a of the contactor 19.

In this state, as the sewing machine operates, the first cam wheel 12 is rotated clockwise in the drawing in conjunction with the rotation of the main shaft of the sewing machine (not shown), and the clutch is connected to rotate the second cam wheel 12. 14 is also rotated integrally with the first cam wheel 12.
As a result, the contactor 19 receives the action of the uneven cam surface 15a of the first control cam 15 via the contact portion 19a, and as shown in FIG. It is oscillated between. The swinging motion is transmitted to a needle bar (not shown) via a transmission means including a swing link 33, etc.
The needle is oscillated laterally with a large amplitude. in this case,
When the contact portion 19a of the contactor 19 engages with the valley portion of the uneven cam surface 15a, the needle moves to the left, and when it engages with the peak portion, the needle moves to the right.

Furthermore, in this case, the auxiliary contact 22 is swung by the action of the zigzag basic cam 13, and the connection lever 27 is swung; When the contact 1
Since the phases of both cams 13 and 15 are set such that the contact portion 19a of the contact member 19 engages with the convex portion of the first control cam 15, the contact pin 32 of the contactor 19 is connected to one side edge of the connection lever 27. There is no interference with the contactor 19, and no support is provided to the swinging movement of the contactor 19. Furthermore, in this case, a feed adjuster (not shown) is set to a position where the feed amount is zero. Therefore, as shown in FIG. 2a, the front bar tacking portion H1 of the buttonhole is formed with a large amplitude and a feed amount of 0.

As shown in FIG.
When engaged with the flat cam surface 15c in a, the clutch between the second cam ring 14 and the main shaft of the sewing machine is disengaged, and the rotation of the second cam ring 14 is stopped.
At the same time, the feed adjuster is rotated to a position where minute reverse feed is set, and the workpiece cloth is transferred in the reverse direction by minute feed. As the sewing machine continues to operate in this state, the first cam wheel 12 continues to rotate, giving the auxiliary contact 22 an oscillating motion between the solid line position and the two-dot chain line position shown in FIG. be done. Therefore, the connecting lever 27 is also swung between the solid line position and the two-dot chain line position in the figure, and is swung toward the contact 19 through the engagement between the first contact surface 30 and the contact pin 32. Exercise is given. The oscillating motion is such that the auxiliary contact 22 engages with the peak of the zigzag basic cam 13, the connecting lever 27 is rotated clockwise to the maximum, and the contact 19 is moved between its contact pin 32 and the first contact. The connecting lever 27 is rotated to the two-dot chain line position through the engaging portion with the contact surface 30 and the connecting lever 27 is rotated so that the auxiliary contact 22 is rotated to engage with the valley portion of the zigzag basic cam 13 as shown in the figure. The contact 19 rotates toward the solid line position, and the contact portion 19a engages with the concave portion of the uneven cam surface 15a of the first control cam 15 of the second cam wheel 14, which is stopped. The formation of the left edge overlocking part H2 of the buttonhole shown in FIG. 2a is performed with a medium amplitude and a small feed amount.

In this way, when the left edge overlocking part H2 has been formed by an amount approximately corresponding to the length of the buttonhole, the clutch is connected and the rotation of the second cam ring 14, which had been stopped until now, is restarted. Ru. When the second cam wheel 14 resumes clockwise rotation from the position shown in FIG.
At point a, the needle swings under the action of the uneven cam surface 15a, imparting a large lateral swinging motion to the needle.
At the same time, the feed adjuster is switched to the zero feed position. Therefore, as shown in Fig. 2a, the rear bar tacking part H3 of the buttonhole has a large amplitude.
It is formed following the left edge overcast area H2 with a feed amount of 0. In addition, when forming this bar-tacking portion H3, the connecting lever 27 swings under the action of the zigzag basic cam 13, but it is important that the connecting lever 27 does not interfere with the swinging movement of the contactor 19 when forming the front bar-tacking portion H1. Same as in case.

As shown in FIG.
, the pin 25 of the switching lever 24
moves to the small radius portion 16a of the second control cam 16, and the switching lever 24 is rotated clockwise. Therefore, the coupling lever 27 is moved to the other control position, and the contact pin 32 of the contactor 19 faces the second contact surface 31 of the coupling lever 27 . The connection lever 27 continues to swing between the solid line position and the two-dot chain line position in the figure in conjunction with the swing of the auxiliary contact 22 due to the rotation of the zigzag basic cam 13. Therefore, the contact 19 is connected to the connecting lever 27.
When rotating to the two-dot chain line position, the second contact surface 3
1 and the contact pin 32, and when the connecting lever 27 is rotated to the solid line position, the contact portion 19a of the first control cam 15 It is rotated to a position where it comes into contact with the flat cam surface 15b and its position is regulated. The rotation of the contact 19 to the two-dot chain line position is the same as when the contact portion 19a engages with the convex portion of the uneven cam surface 15a, and therefore the needle drop position at that position is the bar-tacking portion H3. It matches the right end needle drop position when sewing. Also, at this time, the feed adjuster is switched to a position where minute normal feed is set, and the formation of the right edge overlocking section H4 following the rear bar-tacking section H3 is performed with medium amplitude and minute forward feeding. In the initial stage of forming the right edge overlocking portion H4, the second cam ring 1
Although the second cam ring 14 is rotating, the rotation of the second cam ring 14 is stopped after sewing equivalent to seven stitches has been performed. Therefore, as the sewing machine continues to operate, the right edge overlocking portion H4 continues to be formed in the same manner as described above.

In this way, the sewing of the right edge overlocking part H4 continues, and when the formation of the right edge overlocking part H4 almost reaches the first formed front bar tacking part H1,
The clutch is engaged and the second cam wheel 14 resumes rotation.

As a result, as shown in FIG. 6, the contact portion 19a of the contactor 19 rides on the tacking cam surface 15d, and the pin 25 of the switching lever 24 moves against the shorter inclined portion 16d of the second control cam 16. It passes through and reaches the large radius portion 16b. Therefore, the needle is moved slightly inward from the right end needle drop position shown in FIG. Opposite the first abutment surface 30 of the lever. In this manner, when the contact portion 19a of the contactor 19 rides on the tacking cam surface 15d, the clutch is immediately disengaged and the second cam ring 14 is stopped in that state. Also, at this time, the feed adjuster is switched to a position where the feed amount is slightly reversed. On the other hand, the first cam ring 12 continues to rotate in the same manner as described above, the auxiliary contact 22 is swung, and the connecting lever 27 is also swung, but as is clear from FIG. The swinging of the connecting lever 27 is caused by the contact 19 engaged with the valley of the uneven cam surface 15a, that is,
The contact 19 with the needle moved to the left end position of the left edge overlocking portion H2 is moved to the left edge overlocking portion H2.
It moves only within the range of moving from the left end corresponding position to the right end corresponding position. Therefore, the connecting lever 27 does not contact the contact pin 32 of the contact 19, which has the needle located in the right edge stitching part H4, and the contact 19 is engaged with the cam surface 15d for tacking. hold. Therefore, by operating the sewing machine in this state, as shown in FIG. 2b, after the right edge overlocking part H4 is formed, the tacking stitch H5 is formed at a position slightly inward of the right end needle drop point of the front bar tacking part H1. The operator only has to stop the sewing machine after sewing 3 to 4 stitches.
In this way, as it is clear from Fig. 2c, the overseam has moved slightly inward due to the tightening of the thread, so the right end needle drop point of the right overseam area H4 and the sewn stitch can be H5 matches.

In addition, in the above embodiment, the buttonhole sewing was performed in the order of the front left side, rear part, and right side, but the first and second buttonholes were sewn in this order.
The transfer relationship between the control cams 15 and 16 may be changed to perform the transfer in the reverse order. In this case, as a matter of course, the tacking stitch H5 is formed on the left side, contrary to the previous embodiment.

Effects of the Invention As exemplified in the examples above, in this invention, the cam surface for tacking on the first control cam is formed to have a height located between the heights of the concave and convex portions of the concave and convex cam surface. At the same time, when performing the tacking stitch, the second control cam is controlled so that the connecting member is located at the control position at the time of forming the edging part on the opposite side to the edging part on the side where the tacking stitch is placed. By forming the cam surface, the needle drop point of the overlocking stitch and the needle drop point of the tacking stitch coincide with each other, so that buttonhole stitching can be performed that is favorable in terms of appearance.

[Brief explanation of the drawing]

Fig. 1 shows an overlock stitch made by a conventional buttonhole sewing machine, and Fig. 1a is a front view of the stitch showing the state in which each sewing part except the tacking stitch has been completed; b is a front view showing the apparent relationship between the tacking seam and other seams, and c is a front view showing the actual positional relationship between the tacking seam and other seams; Fig. 2 shows an embodiment embodying this invention, in which Fig. 2a is a front view showing each seam except the tacking seam, and Fig. 2b is a front view showing the tacking seam and other seams. Figure c is a front view showing the actual positional relationship between the bartacking seam and other seams, and Figures 3 to 6 are the front bartacking area and left edge, respectively. FIG. 2 is a partially cutaway front view showing the overlocking part, the right edge overlocking part, and the main parts during sewing of the tacking stitch. Zigzag basic cam...13, first control cam...
...15, Uneven cam surface...15a, Flat cam surface...
15b, flat cam surface...15c, cam surface for tacking...15d, second control cam...16, large radius part...16c, inclined part...16d, contactor...1
9, Auxiliary contact...22, Connection lever...27,
Bar tacking part...H1, H3, left edge overlocking part...
H2, right edge overcast area...H4, tacking seam...
...H5.

Claims (1)

[Scope of claim for utility model registration] Left and right overlocking parts of buttonhole sewing H2, H
Zigzag basic cam 1 that rotates in conjunction with the main shaft of the sewing machine to generate the needle rocking movement in the formation of 4.
3, a plurality of uneven cam surfaces 15a for forming the bar tacking parts H1 and H3 for buttonhole sewing, and the needle swinging momentum according to the zigzag basic cam 13 when forming each of the left and right edge stitching parts H2 and H4. A pair of flat cam surfaces 15b, 15c for regulating
and a tacking cam surface 15d that sets the falling position of the needle in forming the tacking stitch performed at the end of buttonhole sewing. a clutch means which is coupled and disengaged in connection with the transfer of the work cloth in order to rotate or stop the clutch in synchronization with the rotation of the main shaft of the first control cam 15; and each cam surface 15 of the first control cam 15 thereof.
a, 15b, 15c, and 15d, and is operatively connected to the needle bar support frame.
9, connecting members 22, 27 for transmitting the movement according to the zigzag basic cam 13 to the contactor 19 when forming the left and right edge overlocking parts H2, H4, and connecting members 22, 27 in two control positions. The range of needle oscillation movement according to the zigzag basic cam 13 is adjusted between the overlocking portions H2 and H.
cam surface 16a, which is changed and set in accordance with the formation of 4;
16b, and a second control cam 16 that rotates integrally with the first control cam 15, the sewing machine is capable of automatically performing buttonhole sewing accompanied by tacking. The tacking cam surface 15d on the top 15 is formed to have a height between the heights of the unevenness of the uneven cam surface 15a, and when performing the tacking, the tacking stitch H5
The cam surface of the second control cam 16 is formed such that the connecting members 22 and 27 are located at the control position when forming the hemline portion H2 on the opposite side to the hemlock portion H4 on the side where the hemlock portion H4 is arranged. This buttonhole sewing machine is characterized by: