JPH0526519B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a thread trimming device for a cycle sewing machine that performs lockstitching, button stitching, bartitching, tight stitching, etc. in a chain stitching machine. It is.

(Prior Art) Conventionally proposed thread trimming devices for sewing machines use solenoids and electrically complex circuits to perform the thread trimming operation, as shown in Japanese Patent Publication No. 59-19714. It was carried out using However, although this device allows for fine timing adjustments, it is very expensive, and mechanical fixed-position stop type sewing machines such as cycle-type sewing machines do not use expensive electromagnetic motors.
This type of sewing machine had a defect that made it unsuitable.

Also, the timing of thread cutting is just before the sewing machine completes one cycle pattern and stops.
Moreover, since it is desirable that the thread trimming catch be operated slowly, the conventional device is unsuitable for cycle-type sewing machines. This conventional device requires the catcher to reciprocate, scoop and cut the thread, and return to its original position during the half-rotation of the upper shaft before the thread trimming cam stops operating from near the bottom dead center of the needle bar to the top dead center. It was hot. As described above, since the thread cutting operation is fast in the conventional case, there was a drawback that the thread cutting operation could not be performed reliably.

(Problems to be Solved by the Invention) The present invention attempts to solve problems such as the conventional thread cutting operation being fast and thread cutting not being possible reliably.

[Structure of the invention]

(Means for Solving the Problems) Therefore, the present invention provides a main shaft rotatably supported on a frame of a sewing machine, a needle bar that moves in conjunction with the main shaft, a hook shaft that synchronizes with the main shaft, and a needle bar that moves in conjunction with the main shaft. A cycle sewing machine having a feed cam that rotates at a reduced speed and a stitch number adjustment wheel that rotates in synchronization with the feed cam, a thread trimming operation link and a clutch member that operate using the stitch number adjustment wheel as a signal source, and a hook shaft. The thread cutting cam is provided with a thread cutting cam and a catch that moves reciprocally by the operation of the thread cutting cam. The cam groove is provided with a cam groove that moves back and forth beyond the point of contact between the blade part and the fixed part and stops, and this is used as a means to solve the problem.

(Function) Now, the thread trimming operation signal is mechanically transmitted to the catcher in a reliable manner by using the stitch number adjustment wheel that rotates once per cycle as the signal source, and the driving source for the thread trimming operation is the shaft that synchronizes with the main shaft. One revolution of the shaft is used to perform the thread trimming operation using a thread trimming cam attached to the hook shaft.The thread trimming operation is performed in one-way stroke by the thread trimming cam. It moves back to the point beyond the contact point, and the return stroke to the standby position is instantaneously returned by the next start signal.

(Example) Examples of the present invention will be described below with reference to the drawings. Figs. 1 to 9 show examples of the present invention. In the figure, reference numeral 1 denotes a stop motion table pin, and a stitch number adjustment wheel 14 is attached to the decelerated camshaft 13a, and the stitch number adjustment wheel 14 determines the number of stitches required for one cycle of the cycle sewing machine. So, one cycle of the sewing machine consists of one rotation (18 stitches) and half a rotation (half cycle, 9 stitches). Also, the stop arm 10 is attached to the stop motion table pin 1 by a set screw 9.
A stop arm roller 11 is attached to the tip of the arm 10 with a set screw 12. 1
3 is a set screw for fixing the stitch number adjustment wheel 14.

Further, a thread cutting arm 2 is attached to the stop motion table pin 1 by a set screw 3, and a thread cutting link 4 is attached to the tip of the thread cutting arm 2. A thread cutting connection lever 6 and a thread cutting operation link 17 are attached to the thread cutting link 4 with a set screw 5, and a thread cutting operation lever 23 is attached to the link 17 with a set screw 22 and a nut 21. A thread trimming cam lever 24 is connected to.

The thread trimming operation signal is generated when the stop arm roller 11 enters the groove 14a provided on the outer periphery of the stitch number adjustment wheel 14, and the thread trimming arm 2 moves downward via the stop arm 10 and the stop motion table pin 1. The thread trimming cam lever 24 is moved against the spring 39 by a link consisting of the thread trimming link 4, the thread trimming connection lever 6, the thread trimming operating link 17, and the thread trimming operating lever 23, and a set screw 42 is attached to the tip of the thread trimming cam lever 24. The thread trimming cam lever pin 41 attached to the thread trimming cam lever pin 41 enters the groove 33a of the thread trimming cam 33 which is fixed with a set screw 34 to a hook shaft 35 which is synchronized with a main shaft (not shown).

The thread trimming cam lever 24 is attached to the thread trimming cam lever shaft 4
0, and the shaft 40 is fixed to the thread trimming bracket 37 by a set screw 38. 39 is a thread trimming cam lever spring. The thread trimming cam lever pin 41 is engaged with a groove in a slide shaft lever 29 attached to the slide shaft 32. A slide shaft collar 18 is fixed to the slide shaft 32 by a set screw 19. 20 is a slide shaft spring, 30 is a slide shaft lever pin screw, 31 is a slide shaft lever set screw, 25 and 27 are bracket mounting plates, 26
28 is a bracket set screw, and 28 is a bracket mounting plate set screw. Since the hook shaft 35 moves at twice the speed of the needle movement, the thread trimming cam 33 moves 180° during the 1/4 round (270° to 360°) until the sewing machine stops.
Turn (half a turn).

The cam groove 33a of the thread cutting cam 33 has a shape shown in the developed view of FIG.
It is designed to retreat at part b. Therefore, the thread cutting cam 33 rotates by 180°, thereby cutting the groove 33.
Since the thread trimming cam lever pin 41 inserted in a is engaged with the groove of the slide shaft lever 29, the slide shaft 32 slides forward and then stops at a slightly backward position by the portions a and b of the groove 33a. do.

A thread cutting connecting rod 44 is connected to the slide shaft 32 by a set screw 43, and a moving knife link 45 is connected to the connecting rod 44 via a moving knife lever 46. A catcher 49 is connected to the moving female link 45. 50 is a catcher eccentric, 51 is a catcher set screw, and 52 is a catcher pin. Further, 47 is a fixed knife, 48 is a needle hole plate set screw, and 36 is a hook shaft bush. The thread cutting connection lever 6 has a fork lever shaft 8 at the center of the fork.
Collars 15 fixed to the shaft 8 with set screws 16 are provided on both sides of the lever 6 to prevent the lever 6 from moving. 7 is a set screw for the bifurcated lever shaft 8.

Now, when the slide shaft 32 moves due to the rotation of the thread trimming cam 33, the catcher 4 is moved via the thread trimming connecting rod 44, moving knife lever 46, and moving knife link 45.
9 moves in the direction of the arrow in FIG.
9 holds only two of the two needle threads and one bobbin thread, the needle thread and the bobbin thread on the fabric side, and cuts the threads with the fixed knife 47.

The thread cutting portion of the catcher 49 passes through the blade of the fixed knife 47, and when it passes through this blade again on the return stroke, the sewing machine stops. Then, during the next cycle of starting operation of the sewing machine, when the thread trimming arm 2 rises and the thread trimming cam lever pin 41 comes out of the cam groove 33a of the thread trimming cam 33, the slide shaft 32 is moved by the force of the slide shaft spring 20. , it instantly returns to the starting position.

〔Effect of the invention〕

Since the present invention is constructed as described in detail above, a reliable mechanical operation can be transmitted to the catcher using the thread trimming operation signal as the signal source, which is the stitch number adjustment wheel that rotates once per cycle. In addition, the thread trimming operation by the thread trimming cam is performed in a one-way stroke, and after the thread trimming, the thread trimmer moves back to the point beyond the contact point between the catcher blade and the fixed part, and the return stroke to the standby position is performed before the next start. It recovers instantly by a signal. Therefore, according to the present invention, since the movement of the catcher during thread cutting is slowed down, thread rake errors are reduced and thread cutting can be performed reliably.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a plan view of the thread cutting device, FIG. 2 is a side view of the same, FIG. 3 is a sectional view taken from A to A in FIG. 1, and FIG. Figure 5 is a perspective view of the thread trimming cam working mechanism;
7 and 8 are perspective views for explaining the thread cutting state, and FIG. 9 is a developed view of the cam groove of the thread cutting cam. Explanation of the main parts of the diagram, 2... Thread cutting arm, 4...
Thread trimming link, 14... Stitch number adjustment wheel, 24... Thread trimming cam lever, 29... Slide shaft lever, 3
2...Slide shaft, 33...Thread trimming cam, 33a
...Cam groove, 35 ... Hook shaft, 41 ... Thread trimming cam lever pin, 47 ... Fixed knife, 49 ... Catcher.

Claims (1)

[Claims] 1. A main shaft rotatably supported on the frame of the sewing machine, a needle bar that moves in conjunction with the main shaft, a hook shaft that synchronizes with the main shaft, a feed cam that rotates at a reduced speed from the main shaft, and a needle bar that moves in synchronization with the main shaft. In a cycle sewing machine having a rotating stitch number adjustment wheel, a thread trimming operation link and a clutch member that operate using the stitch number adjustment wheel as a signal source, a thread trimming cam provided on a rotary hook shaft, and a thread trimming cam provided on the hook shaft, and and a catcher that moves reciprocally, and the thread cutting cam is provided with a reciprocating catch, and the thread cutting cam cuts the thread in cooperation with a fixed blade in reciprocating motion until the thread is cut beyond the point of contact between the catcher blade and the fixed blade. A thread cutting device for a cycle sewing machine characterized by being provided with a cam groove that moves back and forth and stops.