JPS6243715B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a looper thread supply device for a sewing machine, which feeds out an amount of thread from a thread supply source to the looper side in proportion to the amount of cloth feed of the work cloth, and beautifully delivers the thread to the looper side. The present invention provides a looper thread supplying device capable of forming a seamless stitch.

[Prior art] A conventional looper yarn supply device is, for example,
As shown in Japanese Patent No. 5534, a thread feeding cam plate attached to the drive shaft of the sewing machine allows the looper thread to be fed from the thread supply source to the looper side via a thread tension device.

[Problems to be solved by the invention] However, in the conventional method, the amount of yarn fed out is always constant regardless of the amount of cloth feed, so the amount of yarn consumed is small at the minimum cloth feed, so the thread tension regulator and looper are The looper thread becomes slack between the threads, and as a result, the stitches become loose, resulting in stitches with poor thread tightness.Furthermore, at maximum fabric feed, the amount of thread consumed is large, resulting in a shortage of thread, and as a result, the stitches become loose. There was a tendency for the fabric to twitch and cause so-called sewing shrinkage.

In particular, in a double chainstitch seam, as shown in FIG. 9, the needle thread N is
On the other hand, there are three looper threads T in parallel on the lower side of the work cloth W, so if the fabric feed amount is changed, the looper thread T will be three threads longer than the needle thread N. It will be reduced by two times. Therefore, the above-mentioned tendency was remarkable in the double chainstitch looper thread. Because of this tendency, in conventional sewing machines, when the fabric feed amount is changed, it is necessary to adjust the thread tension of the looper thread and sewing machine needle thread by operating the thread tension controllers, and this adjustment is extremely difficult. It was troublesome.

In order to solve this problem, the present inventor has devised a method in which a thread payout body is fixed to a horizontal feed shaft that imparts a horizontal feed motion to the feed dog, and the amount of thread payout is made proportional to the amount of cloth feed. This method has made it possible to largely eliminate the above-mentioned problems. However, even with this method, new problems have been discovered. That is, when the looper moves forward toward the needle and captures the needle thread loop, and then moves back to release the needle thread loop, slack in the looper thread occurs between the thread tension device and the looper. Although this is generally known, the thread feeding body cannot promptly absorb the amount of slack in the looper thread, which may adversely affect the formation of seams.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems, and its purpose is to automatically change the amount of looper yarn fed in proportion to the amount of cloth feed, and to create a beautiful To provide a looper thread supply device for a sewing machine capable of forming stitches.

[Example] An example in which the present invention is embodied as a looper thread feeding device guided to a double chain looper of an overlock sewing machine that forms a double chain stitch and an overlock stitch will be shown below. The details will be explained with reference to FIGS. 1 to 5.

In the figure, reference numeral 1 denotes the main body of the overlock sewing machine, in which a main shaft 2 is rotatably supported, and a needle bar 3 that moves up and down in conjunction with the main shaft 2 is slidably supported at the top. There is. Two sewing machine needles 4 and 5 are attached to the lower end of the needle bar 3, and one needle 4
is for forming an overlock stitch along the edge of the cloth cut by the cutter device 6 in cooperation with an under looper and an over looper (not shown). The other needle 5 is connected to the main shaft 2.
This is for forming a double chain stitch in cooperation with the double chain looper 7, which is swung in the left-right direction and reciprocated in the front-back direction in conjunction with the double chain looper 7.

8 is a throat plate attached to the sewing machine body 1 below the sewing machine needles 4 and 5, and needle holes 9 and 10 and a long groove 11 for retracting a feed dog to be described later from the upper surface are parallel to each other along the cloth feeding direction. Multiple pieces are formed.

Reference numeral 12 denotes a work cloth support plate disposed on the sewing machine main body 1 so as to form the same plane as the upper surface of the throat plate 8, and a cover body covering the left lower part and front lower part of the sewing machine main body 1 below the work cloth support plate. 13 is attached, and a part 14 on the back side is attached to the sewing machine main body 1.
The main body 1 is rotatably supported and can be opened at the rear left side of the main body 1.

Reference numeral 15 denotes a feed dog that appears and retracts from the upper surface of the throat plate 8, and is moved in four feeds so as to transport the work cloth W in cooperation with the presser foot 16 pressed against the throat plate 8. Reference numeral 17 denotes a cloth feed imparting device for imparting a four-feed motion to the feed dog 15, whose forked base end is rotatably and slidably supported on a shaft 17a fixed to the sewing machine body, and is openable. A feed bar 18 with the feed dog 15 attached to its end, and a square piece 1 that engages with the feed bar 18.
a first eccentric body 20 fixed on the main shaft 2 of the sewing machine in order to give vertical movement to the feed table 18 via a second eccentric body 21 disposed on the main shaft 2; A horizontal feed shaft 23 that is swung by the action of the second eccentric body 21 via a connecting rod 22 that holds the second eccentric body 21, and one end of which is connected to the projecting arm 24 of the horizontal feed shaft 23 and the other end. is connected to a lever 25 connected to the feed base 18.

In addition, the second eccentric body 21 is manufactured by Japanese Utility Model No. 52-57844.
As shown in the above publication, an operating rod 2 is always connected to the main shaft 2 so as to rotate together with the main shaft 2, and is slidably disposed on the front side of the sewing machine main body 1.
6 is pressed inward (direction F in FIG. 4) against the spring 27, the main shaft 2 and the second eccentric body 21
By disengaging the connection with the main shaft 2 and rotating the main shaft 2 in that state, the amount of eccentricity of the second eccentric body 21 with respect to the axis of the main shaft 2 is changed, and accordingly, the amount of rocking of the horizontal feed shaft 23 is changed. The amount of feed of the feed dog 15 is changed accordingly. The second eccentric body 21, the operating rod 26, and the like constitute cloth feed amount changing means.

Reference numeral 28 denotes a thread tension device disposed on the left side of the sewing machine main body 1, and a thread stand (not shown) which is a thread supply source.
This is for applying a required thread tension to the looper thread T guided by the double ring looper 7, and includes two thread guide parts 29 and 30. 3
Reference numeral 1 designates a lever body serving as a yarn feeding body whose base end is attached to the left end of the horizontal feed shaft 23 with a screw 32, and a forked yarn engaging portion 33 is formed at the open end. 34 is a thread hook attached to the left side of the sewing machine main body 1 near the engaging portion 33;
The open end is bent into a U-shape so as to sandwich the thread engaging portion 33, and thread hooking portions 35 and 36 are provided on opposite sides of the engaging portion 33, respectively. Note that the base ends of the lever body 31 and the thread hanging body 34 are each formed into a forked shape, so that the respective mounting positions can be adjusted.

37 is a stepped screw 3 on the left side of the sewing machine body 1.
A thread take-up spring as a thread take-up means is attached at 8, and one end thereof is locked to the sewing machine body 1, and the other open end is provided with a thread engaging portion 39. It engages with the looper thread T between the thread tension device 28 and the double ring looper 7 and acts to absorb the slack of the looper thread T that occurs between them. Reference numerals 40, 41, and 42 are thread guide bodies attached to the sewing machine main body 1, respectively.

As shown in FIG.
8, thread guide section 30, thread guide section 35 of thread hook 34,
The thread is guided to the double ring looper 7 via the thread engaging part 33 of the lever body 31, the thread guide part 36, the thread guide 42, the thread engaging part 39 of the thread take-up spring 37, and the thread guides 40, 41.

Next, when the sewing machine is driven, the feed dog 15 is operated by the cloth feed applying device 17 to transfer the work cloth W, and the sewing machine needle 5 and the double ring louver 7 move the feed dog 15 to the position shown in FIG. A double chainstitch seam is formed as shown.

At this time, the lever body 31, which is activated as the horizontal feed shaft 23 swings, reciprocates as shown by the arrow r in FIG. The looper thread T is fed out to the double loop looper 7 side via the thread tension device 28, thereby supplying the looper thread T to the double loop looper 7 in an amount necessary for forming a double chainstitch.

Further, when the eccentricity of the second eccentric body 21 of the cloth feed applying device 17 is changed and the cloth feed amount is changed, the swing amount of the horizontal feed shaft 23 is changed, and accordingly, the lever body 31 swings. The amount of movement is also changed, and the amount of looper yarn T fed out by the lever body 31 is changed in proportion to the amount of cloth feed. In this way, even if the cloth feed amount is changed, the thread amount is also changed in proportion to the cloth feed amount, and the looper thread T is supplied to the double chain looper 7 by the thread weight necessary to form the double chainstitch stitch. be done. In addition, since the thread take-up spring 37 always absorbs slack in the looper thread, the sewing condition is good and it is possible to always form beautiful double chainstitch stitches.

Next, details of a second embodiment embodying the present invention will be explained with reference to FIGS. 6 to 8. Incidentally, the same parts as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

In the figure, reference numeral 50 denotes a thread-taking rotary body as a thread-taking means attached to the left end of the main shaft 2, and two cam bodies 52 having a cam surface 51 on the outer periphery are formed in parallel. A frame 53 is attached to the left side of the sewing machine body 1 in the vicinity of the thread take-up rotating body 50, and is provided with an opening 54 through which a portion of the cam body 52 projects. Reference numeral 55 denotes a yarn handling body attached to the frame body 53, and the open end thereof is arranged to extend substantially parallel to the center of the two cam bodies 52. 56 is a thread guide portion formed on the frame 53, and 57 and 58 are thread guides attached to the frame 53.

As shown in FIG.
8, thread guide section 30, thread guide section 35 of thread hook 34,
Thread engaging part 33 of lever body 31, thread guide part 36, thread guide 42, thread guide 57, cam body 52a, thread handling body 55, cam body 52b, thread guide 58, thread guide part 56, thread guide 41 It is guided to the double ring louver 7 via.

Next, when the sewing machine is driven, the cam body 52 is rotated in the same direction as the main shaft 2 as the main shaft 2 rotates.
The cam body 52 includes a thread handling body 55, a thread guide 57,
58, the thread tension device 28 and the double ring looper 7
It acts to absorb the slack of the looper thread T that occurs between the looper thread T and the looper thread T.

In this embodiment as well, the looper thread T is fed out to the double ring looper 7 side by the action of the lever body 31, as in the first embodiment, and the cam body 52
The slack in the looper thread T that occurs between the thread tension device 28 and the double ring looper is absorbed by the action of
As in the first embodiment, a beautiful double chain stitch is always formed.

It should be noted that the present invention is not limited to the above embodiments, and can of course be implemented in various sewing machines without departing from the gist of the present invention.

[Effects of the Invention] As described in detail above, the present invention provides a method in which, when the cloth feed amount is changed by the cloth feed amount changing means, the amount of looper yarn fed out is changed in proportion to the cloth feed amount,
Moreover, since the slack in the looper thread is always absorbed by the thread take-up means, even if the fabric feed amount is changed during sewing, beautiful stitches can always be created without operating other operating elements such as a thread tension device. can do.

[Brief explanation of the drawing]

Figures 1 to 5 show the first embodiment, where Figure 1 is a slope view, Figure 2 is a left side view, Figure 3 is a plan view, Figure 4 is a slope view, and Figure 5 is a slope view. 6 to 8 show the second embodiment, FIG. 6 is a left side view, FIG. 7 is a plan view, FIG. 8 is an exploded slope view, and FIG. 9 is an exploded slope view. It is a perspective view which shows a double chain stitch. In the figure, 1 is the sewing machine body, 2 is the main shaft, 5 is the sewing machine needle, 7 is the double ring looper, 15 is the feed dog, 17 is the cloth feeding device, 21 is the second eccentric body, 23 is the horizontal feed shaft, 26 is the operating rod, 28 is the thread tension device, 31
is a lever body, and 37 is a thread take-up spring.

Claims (1)

[Claims] 1. A sewing machine having a sewing machine needle that moves up and down, a looper that forms a stitch in cooperation with the sewing machine needle, and a horizontal feed shaft that swings in conjunction with the up and down movement of the sewing machine needle. , a cloth feeding means for transmitting the oscillating motion of the horizontal feed shaft to a feed dog, and transporting the work cloth by the four-feed movement of the feed dog, wherein the oscillating motion of the horizontal feed shaft is cloth feeding amount changing means for changing the cloth feeding amount by the cloth feeding means by changing the amount of oscillation; and a yarn for applying a required tension to the looper yarn guided from the yarn supply source so as to be guided to the looper. a thread tension device, and a thread payout body fixed to the horizontal feed shaft, swinging together with the horizontal feed shaft, engaging the looper thread between the thread tension device and the looper, and paying out the looper thread from the thread supply source. and a thread take-up means arranged to engage the looper thread between the thread tension device and the looper to absorb slack in the looper thread that occurs between them. looper yarn feeding device.