JPH07121315B2 - Needle thread supply device for two-needle sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention enables one needle to be held in a resting state and draws out the thread amount required for forming one stitch from a thread supply source for each stitch formation. The present invention relates to a needle thread supply device for a two-needle sewing machine.

[Prior Art] For example, as described in Japanese Patent Laid-Open No. 1-204694, a seam is always formed by two needles, and one needle is held in a rest state when forming a seam at a corner. A sewing machine is known that is capable of pulling out the threads of the two needles in an amount required for forming each stitch. As shown in FIG. 3, on the needle thread path between the needle and the thread supply source W, the pull-out means for pulling out the needle thread includes a drive roller 1 and an idler which are always rotated in conjunction with the drive source. The needle thread T1 and T2 of both needles (not shown) are sandwiched between the roller 2 and the roller thread T
1, T2 can be pulled out from the supply source W, and before and after that, thread gripping means A1, A2, B1, respectively arranged on the measuring needle threads T1, T2,
B2 enables each thread to be gripped or released, and when releasing it
T1 and T2 can be pulled out, and when the predetermined amount of yarn is pulled out by the rollers 1 and 2, the yarn gripping means on the side of the supply source W
The amount of yarn pulled out by gripping A1 and A2 is set. The respective thread gripping means A1, A2, B1, B2 cause the gripping plate 4 to come into contact with and separate from each other by the action or non-action of the electromagnet 3, and the yarns T1, T2.
The electromagnet 3 is gripped or released from the main body.

When the above-mentioned one-needle state, that is, when one needle is in the rest state, the electromagnets 3 of the yarn gripping means A1 and A2 on the supply source W side act so that the needle thread on the rest side is not pulled out. It is designed to be held in a gripped state.

With such a sewing machine, when forming a seam with two needles, if one lower thread runs out during the two-needle stitching or one needle thread is cut off on the supply source W side, Normally, the bobbin thread is replenished or the thread is connected, but in an actual sewing factory, the missing bobbin thread or the needle on the side where the thread breakage occurs is stopped without doing such work.
In the single-needle state, only one stitch was successively formed (FIG. 4), and then the halfway stitch was continuously formed by the one-side needle in the used state.

[Problems to be Solved] However, when the seam on only one side is continuously sewn as shown in FIG. 4, the needle thread t of the needle in the rest state is in the gripping state as described above, and therefore is not pulled out from the supply source and follows the sewing. The tension gradually increases, and the tension increases as the stitch reaches a long distance, for example, a distance beyond the 10th stitch. Therefore, the cloth sent to the other side in accordance with the sewing is pulled up by the needle thread t in the rest state and rolled up, which interferes with the sewing work to reduce the work efficiency, or the operator touches the rolled up cloth, or In the case of a thick (heavy) cloth, the weight of the cloth causes the needle thread t between the cloth and the needle to lose tension, which causes a defect that the needle thread t connected to the cloth is broken.

Further, at this time, since the needle thread is held by the thread gripping means on the supply source side of the needle thread in the rest state without being pulled out, as shown in FIGS. 5 and 6, as shown in FIGS. 3 The needle thread t sandwiched between the main body and the main body 3 moves so as to come out from between the main body 3 and the grasping plate 4 because the outside of the grasping plate 4 has a weak grasping force, and finally a phenomenon occurs in which it falls out. The needle thread in use and the dropped needle thread t are entangled with each other to interrupt the formation of stitches, and the needle thread t needs to be re-threaded during the next two-needle stitching.

[Means for Solving the Problem] In order to solve such a problem, the present invention uses two needles arranged in parallel in a direction intersecting with the cloth feed direction and separated by an electric action. One-needle resting means capable of separately holding both needles in the upper position in a resting state, and needles separately on the both needle thread paths between the needle thread supply source and the needles by electrically acting or not acting. It has a needle thread gripping means capable of gripping or releasing the thread, and withdrawing means for engaging both needle threads on the needle side of the needle thread gripping means and drawing out the needle thread from the thread supply source. Each time a stitch is formed, the both needle thread gripping means pulls out the needle thread by the pulling out means, and the pulling out control holds the needle thread gripping means of the rest side needle thread in the gripping state in the one needle state where the one needle resting means acts. In a sewing machine that is capable of operating, a signal indicating the rest state of one needle by operation Switch, a detecting means for generating a signal for each revolution of the main shaft of the sewing machine, a counting means for counting the signal of the detecting means, a determining means for detecting counting of a predetermined number of stitches by the counting means, and a single needle state. The control means is operated by counting a predetermined number of stitches by the counting means after the signal is generated, and the control means for controlling the pull-out control in the double-needle state and the pull-out control in the single-needle state alternately by the predetermined number of stitches thereafter is provided. It was

[Operation] With such a configuration, when the number of one needle continues for a predetermined number of stitches, for example, 10 stitches or more, gripping means on the supply source side of the rest side needle thread is gripped for each predetermined number of stitches when the seam is formed thereafter. Alternatively, by controlling the needle thread to be released, the needle thread on the rest side does not remain stationary for a long time and excessive tension is prevented.

[Embodiment] This embodiment of the present invention will be described with reference to the drawings. It should be noted that the same components as those of the conventional one are denoted by the same reference numerals and the description thereof will be omitted.

Reference numeral 5 is a one-needle stop switch for separately turning on the right and left to generate a signal in relation to the operation of an operation member (not shown) that puts one of the needles into a resting state so as to change from the two-needle state to the one-needle state.
Is a pair of single-needle stop electromagnets which are arranged in a one-needle resting mechanism (not shown) and actuate the resting mechanism so as to selectively hold one of the left and right needle bars (not shown) at top dead center by biasing.
Is an energizing circuit for energizing the electromagnet 6 so as to hold one of the left and right needle bars, and 8 is an OR gate for inputting both left and right signals of the one-needle stop switch 5.

Reference numeral 9 is a one-needle release switch that is turned on to generate a signal when the resting state is released in association with the operation of a release operating member (not shown) arranged in relation to the rest mechanism, and 10 is a one-needle release switch 9 at a predetermined time. 2 is a switch determination circuit that determines the output state of the switch.

Reference numeral 11 is an urging circuit for separately urging the electromagnets 3 of the gripping means A1 and A2 on the front side (thread supply source W side) of the rollers 1 and 2 of the thread pulling means. One side needle control circuit for controlling the biasing circuit 11 to bias the electromagnet 3 of the gripping means A1, A2 corresponding to one of the left and right needle threads T1, T2 A double needle control circuit for controlling the energizing circuit 11 so as to energize the electromagnets 3 of the means A1 and A2. Reference numeral 19 denotes a yarn withdrawal amount control means for instructing the amount of yarn to be withdrawn for each stitch and controlling the electromagnet 3 so that the withdrawn yarn amount becomes the above set amount.

Reference numeral 14 is rotation detecting means for generating one pulse in association with one rotation of the sewing machine main shaft (not shown), 15 and 16 are first and second counter circuits for counting the signals of the rotation detecting means 14 at a predetermined time, 17 is the count value N of the first counter circuit
A discriminating circuit for discriminating whether it is 10 or more, and 18 is a discriminating circuit for discriminating whether the count value E of the second counter circuit 16 is smaller than 2 or has reached 10.

The configuration of the present invention is as described above. Next, the operation will be described with reference to the flowchart of FIG.

When the signal from the one-needle stop switch 5 is generated from the two-needle sewing state, the one-needle stop electromagnet 6 corresponding to the selected one needle bar is energized to be in the one-needle state (step). Further, the count value N of the first counter circuit 15 is cleared by this signal (step). The state of the one-needle release switch 9 is discriminated by the switch discrimination circuit 10 (step). When it is off, the first counter circuit 15 is enabled, the first counter circuit 15 counts the signal of the rotation detecting means 14 (step), and the one-side needle control circuit 12 is operated (step), and the control circuit 12 is stopped. The electromagnet 3 of the gripping means A1 or A2 corresponding to the needle thread on the selected side is held in an urging state, and control is performed so that only the needle thread on the use side is pulled out. When the count discriminating circuit 17 discriminates the count value N> 10 (step), that is, when one stitch is sewn, the count value E of the second counter circuit 16 is cleared (step), and the switch discriminating circuit 10 again. Determine the state (step). When it is off, the second counter circuit 16 is enabled, the second counter circuit 16 counts the signal of the rotation detection circuit 14 (step), and the count determination circuit 18 causes the count value E>
Determine 2 (step). Until E> 2 is determined,
That is, the two needles after the ten needles described above act on the both-needle control circuit 13 to control the urging circuit 11 so as to pull out the two needle threads T1 and T2 (step), and when E> 2 is determined, that is, two After the formation of the two-needle stitches by the needles, the one-side needle control circuit 12 is actuated again to carry out the needle thread only on the used side in the same manner as above (step). When the discrimination circuit 18 discriminates E = 10 (step), that is, after performing one-needle stitching of eight stitches, the second counter circuit 16 is cleared and step-is repeated. After the signal of the one-needle stop switch 5 is generated, when a signal is generated from the one-needle release switch, the releasing means operates (step) to release the one-needle state.

In the present embodiment, during the first ten stitches, the feeding of the resting needle thread is prohibited by the control of the one-side needle control circuit 12 because the resting-side needle thread can be fed out during the corner stitching by one needle. The square stitch is set because it is usually within 10 stitches.

In addition, the count determination values of the count determination circuits 17 and 18 in this embodiment are configured to be set arbitrarily.

Further, it may be configured by computer control or by a hardware circuit so as to perform the same operation as the block diagram of this embodiment.

[Effect] According to the invention as described above, when one-needle sewing continues for a predetermined number of stitches or more, after that, the predetermined number of stitches of the one-needle state and the two-needle state of thread pull-out are alternately repeated.
Even if the needle thread connected to the cloth in the resting state is pulled by the movement of the cloth, it is cut by tension or the like, and the cloth is not rolled up to obstruct the sewing work. Further, in the structure of the thread gripping means on the thread supply source side as shown in FIGS. 5 and 6, the needle thread between the gripping plate and the electromagnet body does not come out, and the thread is re-threaded, which is complicated. The effect that work is unnecessary is also obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a control circuit of this embodiment, FIG. 2 is a flow chart of this embodiment, FIG. 3 is a schematic front view of a conventional thread drawing means, and FIG. 4 is one-needle sewing from the middle of double-needle sewing. FIG. 5 is an explanatory view showing the state of the thread gripping means A and the needle thread t, and FIG. 6 is a side view of the gripping plate and the electromagnet in the state of FIG. FIG.

Claims (2)

[Claims] 1. Two needles arranged parallel to each other in a direction intersecting with a cloth feeding direction, and a single needle pausing means capable of electrically holding both needles in an upper position in a resting state. And a needle thread gripping means capable of gripping or releasing the needle thread individually on both needle thread paths between the needle thread supply source and the needle by electrically acting or not acting, and the needle thread gripping means. Also has withdrawing means for engaging both needle threads on the needle side and withdrawing the needle thread from the thread supply source. In the double needle state, both needle thread gripping means withdraws the needle thread by the withdrawing means at each stitch formation. In the sewing machine that enables the pull-out control for holding the needle thread gripping means for the needle thread on the rest side in the one-needle state in which the one-needle resting means operates, a signal indicating the resting state of one needle by operation. The switch (5) that generates the Detecting means (14)
A counting means (15, 16) for counting the signals of the detecting means, and a discriminating means (1) for detecting counting of a predetermined number of stitches by the counting means.
7 and 18), and operates by counting the predetermined number of stitches of the counting means after the signal of the single-needle state is generated, and then the pull-out control of the double-needle state and the pull-out control of the single-needle state are alternately performed by the predetermined stitch number. And a control means (12, 13) for controlling the needle thread supply device in a two-needle sewing machine. 2. The needle thread supply device for a two-needle sewing machine according to claim 1, wherein the predetermined number of stitches to be discriminated by the discriminating means are different.