JPH0630708B2 - Thread breakage detection device for embroidery sewing machines, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to solve the following problems.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for automatically detecting a thread breakage during a sewing operation in an embroidery sewing machine or the like.

(Prior Art) Conventionally, if thread breakage occurs during a sewing operation using an embroidery sewing machine or the like, there is a problem in that a sewn cloth may have a defective product in which no stitch is formed. In order to solve this, in the applicant's company, the amount of thread for sewing is measured every time one stitch is sewn in the sewing machine, and when the amount of thread is 0, it is detected that thread breakage has occurred. Is devising a way to do it. However, in an embroidery sewing machine or the like, when the swing width of the embroidery thread in the embroidery pattern is small, or the amount of the above-mentioned thread to be fed out is extremely small and close to 0 when sewing is performed, even in such a case Had a problem that it was erroneously determined as a thread break even though no thread break occurred.

(Problems to be Solved by the Invention) Except for the above-mentioned conventional problems, the present invention accumulates the amount of progress of a thread over three stitches or more and compares the accumulated value with a predetermined reference value. Detecting thread breakage of an embroidery sewing machine so that even if the amount of thread fed out is small as described above, it can be judged as thread break only when thread break actually occurs without erroneously judging it as thread break. It is intended to provide a device.

The configuration of the present invention is as follows.

(Means for Solving Problems) According to the present invention, a needle bar is vertically movable in a base portion, and a needle for sewing is provided in a lower portion of the needle bar, and the needle bar is vertically moved. In an embroidery sewing machine or the like in which cloth is sewn by the sewing thread supplied through the needle,
A detection device for detecting the amount of progress of the sewing thread and outputting a signal corresponding to the detection amount is attached to a part of the suture supply path, while the vertical movement of the needle bar is performed every three stitches or more. Receiving the signal from the timing signal generator that outputs a signal and the above detection device, accumulates the progress amount between one timing signal of the sewing thread detected by the detection device and the next timing signal, and outputs the accumulated value. Accumulator,
A reference value setting device for setting a reference value of an accumulated value between one timing signal and the next timing signal is provided in advance, and the accumulator, the timing signal generator and the reference value setting device are each provided with a timing signal. Each time it receives, it compares the cumulative value from the one timing signal to the next timing signal with the reference value, and connects a comparator that outputs a yarn break signal when the cumulative value is smaller than the reference value. It is a thing.

(Operation) The advancing amount of the sewing thread is detected every time sewing is performed by the vertical movement of the needle bar. The detected amount of progress is accumulated over 3 or more stitches each time. The accumulated value accumulated over the sewing of three or more stitches is compared with the reference value, and when it is smaller than that, a thread break signal is output.

(Example) Hereinafter, drawings showing an example of the present application will be described. 1 to 3, reference numeral 1 denotes a head portion of an embroidery sewing machine.
In this, 2 is a base frame, 3 is a rotatable main shaft, 4 is a rotary frame which is mounted on the base frame 2 so as to be freely rotatable in a horizontal plane, 5 is a needle bar, and a plurality of needle bars are arranged above and below the rotary frame 4, respectively. It is attached so that it can move freely. 6 is a needle for sewing attached to the lower end of each needle bar,
7 is a cloth presser. Reference numeral 8 indicates a known balance, and 9 indicates a cover. As is well known in multi-axis sewing machines, the rotary frame 4 is rotated by a signal from a needle bar selection circuit so that any one of a plurality of needle bars 5 is positioned at a sewing work position. . As for the needle bar 5 and the main shaft 3, only the needle bar positioned at the sewing work position is connected to the main shaft 3 by a well-known crank mechanism or the like, and the rotation of the main shaft 3 causes the needle bar 5 to rotate.
Is configured to move up and down. As well known, the relationship between the balance 8 and the main shaft 3 is such that the balance 8 is moved up and down by the rotation of the main shaft 3. Reference numerals 10, 11 and 12 denote yarn guide members, respectively, each of which is provided with a plurality of yarn guide holes 10a, 11a and 12a. Reference numeral 13 indicates a known thread tension device. Next, reference numeral 15 denotes a yarn advancing amount detecting member, which is attached to each frame 16. The frame 16 is commonly used for each detection member 15. In the detection member 15, reference numeral 17 is a bearing metal attached to the frame 16, and a rotary shaft 18 is rotatably provided. Reference numeral 19 denotes a rotary body attached to one end of the rotary shaft 18, around which a stitch thread 24 described later is wound once or twice. Reference numeral 20 denotes an encoder for detecting the amount of yarn advancing, and its movable portion 21 (rotating shaft) is attached to the other end of the rotating shaft 18 by using a connector 22. Reference numeral 23 is a thread guide member attached to the frame 16, and has a plurality of thread guide holes 23a. 24 is a thread for sewing, and in this example, an upper thread is shown. Numeral 25 indicates cloth to be sewn, and numeral 26 indicates stitches in the case of embroidery sewing.

In the case of the above structure, the rotation of the main shaft 3 causes the needle bar 5 to move.
Moves up and down, and the needle 6 is used to perform embroidery sewing on the cloth 25 as is well known. In this case, the sewing thread 24 is the thread guide hole 23a,
Thread advancing amount detection member 15, thread tension device 13, thread guide holes 12a, 10a,
11a, the balance 8 and the needle 6 are supplied, and as is well known, the lower thread is sewn and sewn. As is well known, the sewing is performed by rotating the rotary frame 4 to selectively use the plurality of needle bars 5.

When the sewing is performed as described above, the rotary body 19 rotates in accordance with the amount of progress of the thread 24, and as a result, the encoder 20 is
The yarn advancing amount for each needle is detected and output as a pulse signal. The signal is input to the counter circuit 32 illustrated as an accumulator through the selection circuit 31. Therefore, the accumulator 32 sequentially accumulates the detected values of the yarn advancing amount of each needle from the encoder 20. The selection circuit 31 is configured to selectively transmit only the signal from the encoder corresponding to the needle bar during the sewing operation to the accumulator 32 by the selection signal from the needle bar selection circuit in the control device of the sewing machine. There is. On the other hand, in the timing signal generator 33 connected to the main shaft 3, the main shaft 3 is rotated a plurality of times to perform the above-mentioned sewing of several stitches (in this example, there are 4 stitches, but any number of 3 to 10 stitches may be used). A timing signal is output to the comparator 35 each time it is performed. The comparator 35 compares the cumulative value from the accumulator 32 (signal corresponding to the cumulative value) with the reference value from the reference value setting unit 34 (signal corresponding to the reference value) each time the timing signal is input, If the accumulated value is larger than the reference value, a clear signal is given to the accumulator 32 to clear the accumulated value. If the cumulative value is smaller than the reference value, it is determined that yarn breakage has occurred, and a yarn breakage signal is output to the stop command output circuit 36. The stop command output circuit 36, to which this yarn break signal is input, gives a stop command for stopping the operation of the sewing machine to the control circuit of the sewing machine. The reference value setting device 34 is, for example, a switch that can be arbitrarily set manually.

Next, the above operation will be described in more detail using an example of specific numerical values. When the above-mentioned embroidery is sewn, the advancing amount of the sewing thread 24 for each stitch is usually about 0.4 to 13 mm, although it depends on the swing width of the embroidery pattern. In addition, it is about 0.4 mm in the case of tacking. Further, when the upper thread 24 is broken, the amount of progress is naturally 0 mm. On the other hand, when the bobbin thread breaks, the upper thread 24 is slightly pulled out by feeding the cloth 25, and the progress amount is 0.
It is a few mm. Further, the encoder 20 in the detection member 15 is 1
For example, 4 pulses are generated for a yarn advancing amount of mm. When sewing is performed under such a condition, the reference value setting device 34 sets the number of pulses to 10, for example. When sewing is performed in such a state, from the encoder 20 to the accumulator 32, for example, as shown in FIG.
20 and 5 pulses are input. When the sewing of 4 stitches is completed, the cumulative value of the number of pulses 45
And the reference value 10 are compared in the comparator 35. in this case
Since 45 is greater than 10, comparator 35 provides a clear signal to accumulator 32. Further, sewing is continued, but since one stitch or two stitches are sewn as is well known near the end of one embroidery pattern (the same applies at the beginning), the encoder is used.
The number of 20 output pulses has a small value as shown in FIG. However, even in this case, the cumulative value is 25
Since it is larger than the reference value 10, the accumulator 32 is cleared without judging that the thread is broken. On the other hand, when the upper thread 24 is cut at the time shown in FIG. 4B during sewing, the number of pulses output from the encoder 20 becomes zero thereafter. In this case, in the accumulator 32, the previous pulse numbers 10 and 20 are counted, and the cumulative value becomes 30, so at this point it is not judged that the thread is broken yet, and the cumulative value in the next 4-needle sewing period When it reaches 0, the comparator 35 outputs a yarn breakage signal, and the stop command output circuit 36 outputs a stop command.
As a result, the sewing operation of the sewing machine is stopped. After stopping, the thread breakage is corrected as is well known, and the sewing machine is started again. By this activation, a reset signal is given to the accumulator 32 and the accumulated value is cleared.

Next, when the bobbin thread is cut during the sewing operation, for example, at the time of FIG. 4 (c), the upper thread 24 is consumed little by little, so the encoder 20 makes a small number of pulses (as shown in the figure). 3, 2) Output. At the time when this pulse starts to be output, the number of pulses 15, 10 when the thread break has not yet occurred has already been accumulated, so at that time the thread break signal is not output, and in the process of the next 4 stitches. The cumulative value is 7 as shown
Therefore, the thread break signal is output at that time. The subsequent treatment is the same as above.

Next, the reference value setting in the reference value setting device 34 is 1
It is preferable to set it to about 60% of what is obtained by multiplying the average expected travel amount (for example, 1 mm) for each sewing of the needle by the number of stitches to be accumulated. Further, when there are many stitches with a small swing width, the setting of the reference value in the reference value setting device 34 may be made smaller.

The thread advancing amount detecting member 15 may be installed at any place along the supply passage of the thread 24 as long as the advancing amount of the sewing thread 24 can be detected.

The accumulated amount of progress of the sewing thread 24 by the accumulator 32 is 1 for sewing.
A method of accumulating the thread advancing amount at the time of sewing each of the two or more needles immediately before that and the newly detected thread advancing amount each time the needle is performed may be used.

Next, FIGS. 5 and 6 show different examples of the yarn advancing amount detecting member. In the figure, reference numeral 41 denotes a slit plate having a large number of slits 42, which are attached by a collar 43 and a nut 44 which are respectively screwed into the rotary shaft 18e. Reference numeral 48 is a light emitter, and 47 is a light receiver, both of which are attached to the holder 45.

With such a structure, when the rotary plate 19e is rotated by the progress of the sewing thread, the slit plate 41 is integrally rotated. Each time the light from the light projector 46 is received by the light receiver 47 through the slit 42, the light receiver 47 outputs a pulse signal to the accumulator via the selection circuit. In addition, parts that are considered to be the same or equivalent in configuration to those in the previous figure in terms of function are denoted by the same reference numerals as those in the previous figure with the letter e added to omit redundant description.

Next, FIGS. 7 and 8 show an example of sewing the folded-back portion 51 at the edge of the towel 50. In the figure
52 indicates a sewing thread, and the portion 53 close to the side edge of the towel 50 is finely stitched (the amount of progress of the sewing thread is small) and the stitch is fine, and the intermediate portion 54 is a normal stitch (the amount of progress of the thread is large). ) Sewing is done. Such sewing is performed by a sewing machine called a hem sewing machine, and the detection member is disposed along the passage of the sewing thread in the hem sewing machine to detect the same thread breakage as described above. In the case of performing the above-described detection in the hem sewing of such a towel, it is possible to prevent the occurrence of an erroneous detection such that a thread breakage signal is erroneously issued at the time of sewing at the stop sewing portion 53. Further, as shown in FIG. 8, even if the width W of the towel to be sewn is different and the length of one cycle of stop sewn → normal stitch → stop sewn is different, this is not affected. The correct detection of sewing and thread breakage can be carried out without any trouble.

(Effects of the Invention) As described above, in the present invention, when the sewing thread 24 is cut during sewing and its progress is substantially stopped, the progress amount of the sewing thread 24 detected by the detection member 15 is substantially zero. Since the accumulated value remains substantially zero even if several stitches are sewn in that state, the comparator 35 has a feature that it can determine that the value is smaller than the reference value and output a thread break signal.

On the other hand, even when the thread break signal is output when the sewing thread 24 stops traveling as described above, the amount of progress of the sewing thread 24 is substantially reduced when performing embroidery stitching or stop stitching with a small swing width during sewing. Even if it stops, the apparatus of the present invention accumulates the amount of progress of the thread over the sewing of 3 or more stitches and compares the cumulative value of 3 or more stitches with the reference value of 3 or more stitches. Even if the thread stops moving due to such reasons, the stop is usually 1
The number of stitches is ˜2, and then the sewing thread proceeds normally by the normal sewing method, and as a result, the accumulated value becomes large, and it is possible to prevent the thread break signal from being erroneously issued.

As described above, the device of the present invention does not erroneously output a thread breakage signal at that time even if there is small width embroidery stitching or stop stitching during sewing. There is a practical effect that can produce.

[Brief description of drawings]

1 shows a perspective view of a head portion of an embroidery sewing machine, FIG. 2 is a vertical sectional view of a thread advancing amount detecting member, FIG. 3 is a block circuit diagram, and FIG. The figure which shows an example of the count value of an encoder, and the accumulated value of an accumulator, FIG. 5 is a longitudinal cross-sectional view which shows a different example of a yarn advancing amount detection member, FIG. 6 is a front view of a slit plate, FIG. Top view, 8th
The figure is a comparison of towels with different widths. 2 ... Base frame, 5 ... Needle bar, 6 ... Needle, 24 ... Sewing thread, 25 ... Cloth, 15 ...
Thread advancing amount detection member, 32 ... Accumulator, 33 ... Timing signal generator, 34 ... Reference value setting device, 35 ... Comparator.

Claims (1)

[Claims] 1. A base is provided with a needle bar movable up and down, and a needle for sewing is provided on the lower part of the needle bar, and a cloth is formed by a sewing thread supplied through the needle by the vertical movement of the needle bar. In an embroidery sewing machine that is designed to sew
A detection device for detecting the amount of progress of the sewing thread and outputting a signal corresponding to the detection amount is attached to a part of the suture supply path, while the vertical movement of the needle bar is performed every three stitches or more. Receiving the signal from the timing signal generator that outputs a signal and the above detection device, accumulates the progress amount between one timing signal of the sewing thread detected by the detection device and the next timing signal, and outputs the accumulated value. Accumulator,
A reference value setting device for setting a reference value of an accumulated value between one timing signal and the next timing signal is provided in advance, and the accumulator, the timing signal generator and the reference value setting device are each provided with a timing signal. Each time it receives, it compares the cumulative value from the one timing signal to the next timing signal with the reference value, and connects a comparator that outputs a yarn break signal when the cumulative value is smaller than the reference value. A thread breakage detection device for an embroidery sewing machine or the like.