JP3633981B2 - Chain stitch sewing machine - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a chain stitch sewing machine that forms a chain stitch by a looper thread and a needle thread.
[0002]
[Prior art]
When sewing is performed to form an empty ring in which the looper thread and needle thread are knitted after the sewing is finished and the sewing product has come off the presser foot, the sewing product can be taken out after the sewing is finished by presser foot and feed. This is done by cutting the empty ring that was sent out.
[0003]
Further, in the case of performing a ring stitch in which no empty ring is formed in a state where there is no non-sewn product, for example, a decorative stitch (cover stitch) shown in FIG. 3 , a sewing machine is used when the needle is removed from the end of the non-sewn product. If you stop and pull out the looper thread and needle thread, the thread may break. Therefore, in this case, when the sewing product is taken out after the end of the sewing, after sewing to the end of the non-sewn product, the needle bar is raised by rotating the sewing machine backward from the bottom dead center of the needle bar (the needle thread is slackened). Loop is formed), the looper is turned to the front side of the needle, and after the needle thread hanging on the looper is released, the looper thread and needle thread are pulled out and the sewing product is taken out.
[0004]
[Problems to be solved by the invention]
However, the looper is often in the phase where the needle bar bottom dead center is retracted last, so in the case of chain stitching that does not form an empty ring, when taking out the sewn product after the end of sewing, the vicinity of the needle bar bottom dead center When the needle thread loop formed at the time of reverse rotation of the sewing machine is on the front side of the needle, the looper that wraps around the needle thread during the reverse rotation scoops the needle thread loop so that the looper scoops the needle thread loop during forward rotation. Sometimes. When this happens, the needle thread hung on the looper becomes resistance, and the sewn product cannot be taken out.
[0005]
An object of the present invention is to provide a chain stitch sewing machine capable of smoothly taking out a sewn product after the end of sewing when performing chain stitching in which no empty ring is formed in the absence of a non-sewn product.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a chain stitch sewing machine according to the present invention is a chain stitch sewing machine including a rotary needle thread balance that controls the feeding and slack absorption of a needle thread during sewing, and a drive shaft that drives the needle thread balance. And a member that rotates with the drive shaft when the sewing machine rotates in the forward direction and contacts with the needle thread to absorb the slack of the needle thread.
[0007]
[Action]
In the chain stitch sewing machine configured as described above, when the sewing machine is stopped and the needle bar is at the bottom dead center position and then rotated reversely, the needle thread slack absorbing means The rotation causes the needle thread that is about to hang down to move, preventing the formation of the loop. As a result, the needle thread is not scooped even when the looper wraps around the front side of the needle due to the reverse rotation of the sewing machine, and the occurrence of an obstacle to the withdrawal of the needle thread associated with the removal of the sewing product is avoided.
[0008]
【Example】
An embodiment of the chain stitch sewing machine of the present invention will be described with reference to FIGS.
[0009]
The basic structure of this chain stitch sewing machine is the same as that of the conventional chain stitch sewing machine, and the only difference is that the thread pulling arm 4 is newly added to the needle thread balance drive shaft 3 in the arm.
[0010]
The thread pulling arm 4 is rotated when the drive shaft 3 rotates in the forward direction (on the sewing machine) and the drive shaft 3 to which the needle thread balance (rotary balance) 2 that controls the feeding of the needle thread 1 and the absorption of the slack during sewing is fixed. When rotating in the forward direction), it rotates with the drive shaft 3 when rotating in the reverse direction, and absorbs the slack of the needle thread that occurs when the needle bar is raised by rotating the sewing machine in the reverse direction from the vicinity of the bottom dead center of the needle bar. Is.
[0011]
Following the needle thread balance 2, a washer 5, a thread pulling arm 4, a washer 6, a wave washer 7 and a washer 8 are inserted into the drive shaft 3 in order, and the position in the thrust direction is determined and fixed by an E-ring 9. Has been. In this state, the thread pulling arm 4 receives a force in the thrust direction by the wave washer 7 and is pressed toward the needle thread balance 2 side.
[0012]
Near the tip of the yarn pulling arm 4, a contact 4 a is formed so as to protrude toward the axial end of the drive shaft 3. A stopper 10 is provided below the end of the drive shaft 3 to stop the rotation of the yarn pulling arm 4 during normal rotation. Reference numeral 11 also exists in a conventional chain stitch sewing machine, and is a needle thread balance guide that determines the path of the needle thread 1 with respect to the needle thread balance 2, and 12 and 13 are a needle thread guide plate and a thread guide, respectively. .
[0013]
Instead of pressing the thread pulling arm 4 against the needle thread balance 2 by the wave washer 7, the thread pulling arm 4 is attached to the drive shaft 3 via a one-way clutch bearing to control the movement during forward rotation and reverse rotation. You may make it do.
[0014]
In the chain stitch sewing machine configured as described above, the drive shaft 3 continues to rotate normally during normal rotation of the sewing machine, that is, during normal sewing, but the thread pulling arm 4 has a contact 4a that contacts the rotation stopper 10. In contact therewith, while receiving a thrust torque in the axial direction, the rotational movement is hindered (slips with respect to the drive shaft 3), and it is stationary in the state shown in FIG. That is, during the forward rotation of the sewing machine, the thread pulling arm 4 is kept at a lower position where the contact 4a does not act on the needle thread 1. Accordingly, during normal operation (forward rotation) of the sewing machine, the thread pulling arm 4 does not hinder the operation or affect the needle thread 1 or the like.
[0015]
When taking out the sewn product after the end of sewing in the case of carrying out chain stitching in which there is no non-sewn product and no empty ring is formed, the sewing machine is stopped in the state where the needle bar is at the bottom dead center position, and then reversely rotated. . Since the thread pulling arm 4 is always given a thrust torque by the wave washer 7, it rotates in the direction of the arrow shown in FIG. 2 together with the reverse rotation of the drive shaft 3 due to the reverse rotation of the sewing machine. On the other hand, since the supply amount of the needle thread 1 is maximum at the bottom dead center position of the needle bar, the needle thread 1 having the maximum supply amount is sewn to the needle hole due to the needle bar rising by reverse rotation of the sewing machine. A needle thread loop is formed by sagging between objects. However, the contact 4a that is raised by the rotation of the thread pulling arm 4 captures the needle thread 1 and pulls it further, so that the needle thread 1 that is about to be absorbed is absorbed and the state in which the needle thread loop is not formed is maintained. . That is, the needle thread 1 that is about to rise when the needle bar is lifted by the reverse rotation of the sewing machine is absorbed by the lift of the contact 4a of the thread pulling arm 4, and the formation of the loop is hindered. As a result, the needle thread 1 is not scooped even when the looper wraps around the front side of the needle due to the reverse rotation of the sewing machine, and it is possible to avoid the occurrence of trouble with respect to the withdrawal of the needle thread associated with the removal of the sewing product. Therefore, the sewing product can be taken out freely.
[0016]
In the above, the example in which the thread pulling arm 4 absorbs the slack of the needle thread caused by the raising of the needle bar at the time of reverse rotation of the sewing machine has been described. Any member or mechanism is acceptable.
[0017]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0018]
That is, it is possible to prevent the needle thread from being caught on the looper when the sewing machine is reversely rotated when the sewing machine is taken out in the case of performing the chain stitching in which the non-sewn product does not exist and the empty ring is not formed. Objects can be taken out smoothly. Further, the needle thread slack absorbing means can be made independent of other members during normal rotation of the sewing machine, and does not interfere with the normal operation of the sewing machine or affect the needle thread or the like. Furthermore, the needle thread sag absorbing means can fulfill the necessary function with an inexpensive mechanism.
[Brief description of the drawings]
FIG. 1 is a perspective view of the vicinity of a needle thread balance during forward rotation in a chain stitch sewing machine according to the present invention.
FIG. 2 is a perspective view of the vicinity of a needle thread balance at the time of reverse rotation in the chain stitch sewing machine of the present invention.
FIG. 3 is a diagram showing cover stitches.
[Explanation of symbols]
1 Needle thread 2 Needle thread balance 3 Drive shaft 4 Thread pulling arm (needle thread slack absorbing means)
4a Contact 7 Wave washer 10 Stopper

Claims (1)

In a chain stitch sewing machine equipped with a rotary needle thread balance that controls the take-out of needle thread and the absorption of slack during sewing, it is attached to the drive shaft that drives the needle thread balance, and when the sewing machine rotates forward and reversely A chain stitch sewing machine provided with a member that rotates together with the drive shaft, abuts against the needle thread, and absorbs the slack of the needle thread.

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