JPH0221008Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] This invention relates to a double chain stitch sewing machine.

[Prior Art] In a conventional double chainstitch sewing machine, as the needle moves up and down, the looper is moved in an elliptical manner below the needle by a four-bar link mechanism.

[Problems to be Solved by the Invention] This invention attempts to solve the disadvantages of the conventional four-bar linkage mechanism, which increases the number of parts and increases manufacturing costs.

[Means for solving the problem] This invention consists of a needle that carries the upper thread and is moved up and down,
A thread insertion hole for carrying a bobbin thread is formed at one end facing the needle, and a sword tip portion extends in the sewing material feeding direction. A looper drive cam extends from the tip of a looper that is supported to be swingable around an axis perpendicular to the vertical direction and movable in the coaxial direction, and is integrally provided with the swing shaft of the looper. The needle is loosely inserted into a cam groove formed on the end surface in the direction of the rotational axis, and the tip portion is configured to form a gap for insertion of the needle between the needle and the bobbin thread extending from the thread insertion hole to the workpiece. A recess is formed in communication with one side parallel to the vertical movement path of the needle and one side facing the tip of the needle, and the cam groove has a recess that allows the looper to move around the swing axis. a first circumferential cam that moves toward and away from the rotational axis of the looper drive cam in order to swing the tip-like portion into and out of the needle thread loop formed on the needle side; and the first circumferential cam. a second circumferential cam portion formed continuously at a starting end and a terminal end of the section, and formed as a circumferential surface centered on the rotational axis in order to keep the tip-shaped section inserted into the needle thread loop; When the driven body engages with the first circumferential cam portion, the sword tip portion is held on one side of the vertical movement path of the needle, and when the driven body engages with the second circumferential cam portion, the An end cam portion is formed for reciprocating the looper in the direction of the swing axis so that the recess of the tip portion is located on the vertical movement path of the needle, and the tip portion is placed on the sewing material. It is configured to reciprocate along a substantially L-shaped locus that is bent in the direction of the swing axis of the looper at one end in the feeding direction.

[Function] In the present invention, the looper drive cam is rotated as the needle moves up and down, and the cam groove formed with the first circumferential cam part, the second circumferential cam part, and the end cam part is driven into the driven body. are engaged, the looper is swung, and reciprocated along the oscillation axis.

At this time, the driven body engages with the first circumferential cam portion and the end cam portion, so that the tip portion of the looper is inserted into the needle thread loop while being held on one side of the vertical movement path of the needle; Subsequently, the driven body engages with the second circumferential cam portion and the end cam portion, and the looper is moved forward in the direction of the swing axis while the tip portion remains inserted into the needle thread loop. The recess of the shaped part is moved onto the vertical movement path of the needle, and then, when the needle passes through the object to be sewn again and enters the recess, the driven body again moves between the first circumferential cam part and the end cam part. By engaging with the looper, the looper is moved back in the direction of the swing axis, and the tip of the looper returns to one side of the vertical movement path of the needle and separates from the needle thread loop.

In this way, the tip-shaped portion of the looper is reciprocated along the workpiece at one end in the feeding direction in a substantially L-shape bent in the swinging axis direction of the looper, and the tip-shaped portion of the looper is reciprocated at one end in the feeding direction. The needle is inserted into the recess and the needle is surely inserted into the loop of the lower thread together with the upper thread to perform double chain stitching.

[Example] A detailed description will be given below with reference to the drawings. In Fig. 5, 1 is the frame of the sewing machine, and the arm part 1a
and the bed portion 1b are made to protrude in parallel.

2 is the needle. Reference numeral 3 denotes a support body for supporting the needle, which is supported so as to be vertically slidable on a guide rod 4 fixed to the tip of the arm portion 1a. Reference numeral 5 denotes a lever whose center is swingably supported around a horizontal shaft 6, and one end of which is rotatably and slidably connected to the support body 3. The other end of the lever 5 is connected to an eccentric position of a large-diameter wheel 7 via a link 8, and the large-diameter wheel 7 is connected via a belt 11 to a small-diameter wheel 10 rotated by a motor 9. .

As the motor 9 rotates, the small diameter ring 10 and the large diameter ring 7 rotate, the link 8 moves up and down, the lever 5 swings around the shaft 6, and the support 3 moves up and down together with the needle 2.

Reference numeral 12 denotes a sewing object support surface, that is, a needle plate, which is provided on the upper surface of the bed portion 1b facing below the needle 2, and forms a space 14 between it and a bottom wall 13 provided at a distance below the needle plate. ing. Space 14 is bed part 1b
It is open toward the end, and the open surface is covered with a lid 15 that can be opened and closed.

16 is a cam for driving the looper, which is fixed to the end of the shaft 21 that rotates together with the large diameter wheel 7;
The end face facing inward has a cam groove 17 that opens in the same direction as the open face of the space 14. The cam groove 17 is formed into an annular shape around the shaft 21 and includes a circumferential cam portion 17a that is uneven in the radial direction, and an end cam portion 17b that is uneven in the axial direction at the bottom of the groove. Furthermore, the circumferential cam portion 17a is a portion 17a-1 (second circumferential cam portion) that forms a concentric circle with respect to the shaft 21, as shown in FIG.
and a portion 17a-2 (first peripheral surface cam portion) that connects with both ends thereof and rapidly approaches and separates toward the shaft 21.
As shown in FIG. 3, the end cam portion 17b has a shallow groove bottom in the former portion 17a-1 in a direction parallel to the shaft 21, a deep groove bottom in the latter portion 17a-2, and a groove bottom near the connecting portion between the two. Inclined surface 17b at
-1, 17b-2.

Reference numeral 19 denotes a driven arm that follows the cam, and has a pin 19a inserted into the cam groove 17 at its upper end, and a cylindrical boss portion 19 at its lower end that is pivotally fitted to the support shaft 22.
It has b. A looper 28 forms a stitch together with the needle 2, and has a cylindrical portion 28g at its lower end that fits into the boss portion 19b of the driven arm and is fixed with a screw 23. The support shaft 22 is parallel to the shaft 21, that is, extends from the back of the space 14 toward the open end, and the back end is connected to the bottom wall 1.
It is inserted into a hole 24 in a wall that rises at the back of the bottom wall 13, and its other end is supported by a support 25 fixed to the other end of the bottom wall 13. Note that 26 is a spring that presses the driven arm 19 so that it is always in contact with the cam groove 17.

The looper 28 has a tip-shaped portion 28a that extends in an arcuate direction centered on the support shaft 22, and a handle portion that extends from its base end in the radial direction of the shaft. As shown in FIG. 4, the tip 28a is formed by cutting off the other side surface so that the tip 28b is located closer to the side surface on the needle 2 side, and also has a recess that is open on the side surface and upper surface on the needle 2 side. 28c. Furthermore, thread insertion holes 28d and 28e are provided in parallel to the support shaft 22, respectively, at the tip end and the base end end of the sword tip portion 28a, with the recess 28c in between. Both holes communicate with each other through a groove 28f on the side opposite to the needle 2.

This looper 28 carries the bobbin thread led from the thread supply source by passing it through the hole 28d on the base end side, the groove 28f, and the hole 28e on the tip side.

The needle 2 passes through a thread insertion hole provided at its lower part in a direction perpendicular to the feeding direction of the sewing object 29 (left direction in FIG.
The cam 16 rotates counterclockwise in FIG. 1 so that the cam 16 swings parallel to the feeding direction.

The looper 28 is connected to the pin 19a of the driven arm 19 when the needle 2 is at the bottom dead center position as shown in FIG.
is located closest to the axis of the cam groove 17a-2, at the rear of the needle 2 in FIG.
b facing the side at a distance (fourth
(shown as a solid line in the figure).

When the cam 16 further rotates from the above state, the groove 17a-2 of the cam moves away from the axis, and the looper 28 swings to the right as shown by the two-dot chain line. At the same time, the needle 2 begins to rise, and the tip-shaped portion 28a of the looper, which has started swinging to the right, is inserted into the slack of the needle thread, that is, the loop, which is formed at the rear in the figure of the needle 2, and the tip of the looper is inserted into the loop. Insert the bobbin thread folded in half along both sides of the shaped portion 28a. Point-shaped portion 28 that captures the loop of upper thread
After continuing to oscillate, a sloped surface 17 of the cam
Due to the action of b-1, it moves toward the front in the figure along the support shaft 22. In other words, the tip-shaped portion 28a is the fourth
As shown by the dashed line in the figure, it moves approximately in an L-shape when viewed from above. At the same time, pin 19a of the driven arm
reaches the concentric circle portion 17a-1 of the cam groove and stops the swinging of the looper. At this time, the tip 28a is at the position shown by the two-dot chain line in FIG. 4, but the needle 2 has already moved sufficiently upward, and the movement of the tip 28a along the support shaft 22 and the needle 2 are There will be no interference.

As shown in FIG. 1b, the workpiece 29 is fed while the looper 28 is stopped, and at the position where the next stitch is to be formed, the needle 2 passes through the workpiece and descends. As shown in c, the looper 28 enters the recess 28c of the tip 28a, that is, the gap between the bobbin thread and the tip, and the looper 28 moves backward in the figure along the L-shaped trajectory, and the cam Since the groove moves from the concentric circle toward the axis, it begins to swing to the left.

The needle 2 continues its descent and securely captures the loop of thread as shown in FIG. 1d. The looper 28 also releases the loop of the upper thread. When the needle 2 rises again from the bottom dead center position, a new loop of the upper thread is captured by the tip 28a, and then the loop of the lower thread is released. In this way a double chain seam can be formed.

[Effects of the invention] As described in detail above, in the present invention, in order to form a double chain seam, the looper is swung by one cam, and the sword tip of the looper is moved along the workpiece to be sewn. At one end in the feed direction, the looper is reciprocated along a new approximately L-shaped trajectory bent in the direction of the swing axis of the looper, and the needle is inserted into the recess in the tip of the looper to ensure that the looper thread is looped. , through which a needle carrying an upper thread is inserted.

This eliminates the need for the four-bar link mechanism that was conventionally required, making it possible to significantly reduce the number of parts, making it possible to provide an inexpensive double chainstitch sewing machine, and moreover, it is possible to securely attach the needle to the bobbin thread loop. Since it can be inserted, it has the effect of reducing the occurrence of skipped stitches.

[Brief explanation of the drawing]

Figures 1 a to d are views of the needle, looper, and cam portions seen from the end surface direction, and illustrations of their sewing operations;
The figure is a front view of the looper and cam part, Figure 3 is a cross-sectional developed view of the cam, Figure 4 is a plan view showing the positional relationship between the top surface of the looper and the needle, and Figure 5 is a view of the entire sewing machine from the front. FIG. Explanation of symbols, 2...needle, 16...cam, 17...
...Cam groove, 17a...Surrounding cam portion, 17b...End cam portion, 19...Followed arm, 28...Looper,
28a... point-like part, 28c... concavity.

Claims (1)

[Claims for Utility Model Registration] A needle 2 that carries a needle thread and is moved up and down, and a thread insertion hole 28e for carrying a bobbin thread is formed at one end facing the needle and extends in the direction of feeding the workpiece. The sword point portion 28a is provided with a looper 28 that is supported to be swingable around an axis perpendicular to the sewing material feeding direction and the vertical direction of the needle and movable in the coaxial direction. A driven body 19a extending from the tip and integrally provided on the swing shaft of the looper is loosely inserted into a cam groove formed on the end surface of the looper drive cam 16 in the direction of the rotational axis, and the tip-shaped portion 28a has a driven body 19a. , the thread insertion hole 28e
One side of the needle parallel to the vertical movement path and one side facing the tip of the needle are communicated so as to form a gap for insertion of the needle between the thread and the bobbin thread extending from the needle to the sewing material. A recess 28c is formed in the cam groove, and a recess 28c is formed in the cam groove for swinging the looper 28 around the axis of rotation to insert and remove the tip-shaped portion 28a into and from the needle thread loop formed on the needle side. A first circumferential cam 17a-2 that moves towards and away from the rotational axis of the looper drive cam 16, and a first circumferential cam portion 17a-2 that is continuously formed at a starting end and a terminal end thereof, and that has a tip-like portion 28a. a second circumferential cam portion 17a-1 formed as a circumferential surface centered on the axis of rotation in order to maintain the inserted state in the needle thread loop; and a first circumferential cam portion 17a-2 in which the driven body 19a is
When the driven body 19a engages with the second circumferential cam portion, the tip portion 28a is held on one side of the vertical movement path of the needle, and when the driven body 19a engages with the second peripheral cam portion, the tip portion 28a is held on one side of the vertical movement path of the needle.
An end cam portion 17b is formed to reciprocate the looper 28 in the direction of the swing axis so that the recess 28c is located on the vertical movement path of the needle, and the tip portion 28a is located on the sewing object. A double chainstitch sewing machine characterized in that it is configured to be reciprocated along a substantially L-shaped trajectory bent in the swing axis direction of the looper at one end in the feeding direction.