JP2007296230A - Broken needle-detecting device for sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a broken needle-detecting device for a sewing machine, which is allowed to calculate a threshold for detecting the presence/absence of a needle without relying on experience or intuition, and detect a broken needle using the result of the calculation. <P>SOLUTION: The broken needle-detecting device for the sewing machine includes a needle detector and a rotation detector. The device comprises: an oscillation circuit; an A/D converter for converting output voltage of the needle detector from a signal of the oscillation circuit; calculation means for extracting a maximum value of a first data while generating the first data by conversion by the converter, extracting a minimum value from maximum values of the first data every time a rotation pulse signal is generated, while repeating the extraction until the count of rotation pulse signals from the rotation detector reaches a predetermined number, and calculating a reference value for the broken needle from the minimum values after the repeated extraction of the maximum values of the first data; a storage means for storing the reference value for the broken needle; and a determination means for extracting a maximum value of the first data, comparing the maximum value of the first data with the reference value after the rotation pulse signal is generated, and determining a broken needle when the maximum value of the first data is smaller than the reference value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a needle break detection device for a sewing machine that detects a needle break that occurs during sewing of a sewing machine.

  A conventional needle breakage detection device for a sewing machine includes a needle detector disposed near the bottom dead center of the needle and a rotation detector that outputs a rotation pulse signal for each rotation of the sewing machine. There is known one in which needle breakage is determined by the ratio of the detection cycle (see, for example, Patent Document 1). The needle detection pulse from the needle detector is output through a detection circuit attached to the needle detector.

JP-A-11-221392 (page 2-3, FIG. 1-2)

However, in the conventional needle breakage detection device of the sewing machine, the threshold for needle detection pulse determination (needle presence / absence detection) is usually set by a manual sensitivity adjustment member. Such threshold values need to be set in advance, but there are many parts that depend on the experience and intuition of the operator, and they have not been performed efficiently. For this reason, it is difficult to detect appropriate needle breakage.
Therefore, an object of the present invention is to provide a needle breakage detection device for a sewing machine that can calculate a threshold value for detecting the presence or absence of a needle without relying on the experience and intuition of an operator and can detect a needle breakage using this calculation result. It is an object.

  In order to achieve the above object, the present invention comprises a needle detector disposed near the bottom dead center of a needle and a rotation detector that outputs a rotation pulse signal for each rotation of the sewing machine. In a needle breakage detection device for a sewing machine that detects a needle breakage occurring in the oscillation circuit, an oscillation circuit for generating a signal with a constant operation clock, and an output voltage A of the needle detector that is converted based on the signal from the oscillation circuit A maximum value of the first data is extracted while generating the first data by converting the output voltage of the needle detector by the A / D converter based on the signal from the / D converter and the oscillation circuit. Each time the rotation pulse signal is generated from the rotation detector while extracting the value until the rotation pulse signal from the rotation detector reaches a predetermined number, the minimum value is extracted from the first data maximum value. Repeat extraction of maximum value After completion of the return, a calculation means for subtracting a predetermined value from the minimum value to calculate the needle breakage determination reference value, a storage means for storing the needle breakage determination reference value calculated by the calculation means, and a signal from the oscillation circuit Based on this, the output voltage of the needle detector is converted by the A / D converter to extract the maximum value of the first data while generating the first data, and after the rotation pulse signal is generated from the rotation detector, the next rotation pulse is extracted. Judgment means for comparing the first data maximum value with the needle breakage determination reference value until a signal is generated and determining that the needle breakage occurs when the first data maximum value is smaller than the needle breakage determination reference value; It is characterized by having.

  Note that it is desirable to stop the sewing machine motor when the detection of the broken needle by the determination means is continuously generated at least twice.

  According to the present invention, the calculation means extracts the maximum value of the first data while generating the first data by converting the output voltage of the needle detector by the A / D converter based on the signal from the oscillation circuit, When the rotation pulse signal is generated from the rotation detector, the minimum value is extracted from the first data maximum value while repeating the extraction of the first data maximum value until the rotation pulse signal from the rotation detector reaches a predetermined number. Therefore, it is possible to accurately derive a value that is the basis of the needle breakage criterion value. In addition, since the needle break determination reference value calculated by the calculation means is stored in the storage means, it can be used effectively when detecting needle break.

  The output voltage of the needle detector is converted by the A / D converter based on the signal from the oscillation circuit to extract the maximum value of the first data while generating the first data, and the rotation pulse signal is generated from the rotation detector. The first data maximum value and the needle breakage determination reference value are compared between the time when the next rotation pulse signal is generated and when the first maximum value is smaller than the needle breakage determination reference value, If the determination means for determining is provided, the needle detector or the like used during the operation of the calculation means can be used as it is. Furthermore, if a sewing machine motor stop signal is output when needle breakage is continuously detected, a single needle break determination can be interpreted as erroneous detection.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the needle stock 2 to which the needle 1 is attached is fixed to the lower end of the needle bar 3, and the needle 1 moves up and down as the main shaft rotates. When the needle bar 3 is lowered, the tip of the needle 1 passes through the needle hole of the needle plate 4. The needle plate 4 is fixed to the machine frame 5 of the sewing machine, and the needle receiver 6 is fixed to the lower surface of the needle plate 4. Below the needle plate 4, the lower looper 7 moves left and right in a direction perpendicular to the cloth feeding direction F. The upper looper 8 moves up and down across the needle plate 4 while moving left and right in a direction orthogonal to the cloth feeding direction F. In the present embodiment, the needle receiver is fixed to the lower surface of the needle plate. However, the present invention is not limited to this.

  A needle break sensor (needle detector) 9 is disposed near the bottom dead center of the needle 1. This time, EH-605 manufactured by Keyence Corporation was adopted as the needle break sensor 9, and the output voltage from the needle break sensor 9 was set to 0V to 5V. The needle break sensor 9 is fixed to the tip of the bracket 10, and the base end of the bracket 10 is fixed to the machine frame 5 with screws 11. The bracket 10 is refracted by about 20 ° downward from the middle so that the detection surface of the needle break sensor 9 is along the vertical movement direction of the needle. The bracket 10 is fixed to the bracket 10 by a long hole formed in the bracket 10, and the bracket 10 can be adjusted back and forth along the cloth feeding direction F when the screw 11 is loosened. Incidentally, it is desirable to set the gap between the needle 1 and the needle break sensor 9 to 1.0 to 1.2 mm by adjusting the bracket 10 in the longitudinal direction.

  As shown in FIG. 2, the detection surface provided on the front side of the needle break sensor 9 includes a circular portion 9a and a straight portion 9b extending laterally from the circular portion 9a. In 9a. It is also possible to detect needle breakage for a plurality of needles within the range of the portion 9a. Further, as described above, since the detection surface of the needle break sensor 9 is set along the vertical movement direction of the needle, the detection of the needle can be performed stably, and it becomes easier to grasp the time of the bottom dead center. .

  The control according to the present invention is performed by the microcomputer MC, and the microcomputer MC includes a CPU 12, a ROM 13, a RAM 14, and an EEPROM 15 as a basic configuration. The CPU 12 has a known oscillation circuit, and the oscillation circuit generates a signal with a constant operation clock. The ROM 13 stores a basic operation program of needle break detection and teaching, and the RAM 14 stores related data that is sequentially generated from the needle break sensor 9 side. The EEPROM 15 stores a needle breakage determination reference value Z output by teaching. The output voltage of the needle break sensor 9 is amplified by the amplifier circuit 16, and the amplified output voltage is converted into digital first data X by an A / D converter (A / D converter) 17.

  As the CPU 12, a 16-bit microcomputer of H8 / 3694F (model number HD64F3694FX) manufactured by Renesas Technology may be employed. In this case, since the A / D converter is built in the 16-bit microcomputer, the A / D in FIG. The D conversion 17 can be omitted. Incidentally, the operation clock of the 16-bit microcomputer is 20 MHZ, and the processing speed of the A / D converter can be performed at about 12 μsec or less per time. When the 16-bit microcomputer is adopted, the resolution of the A / D converter is 10 bits. Therefore, when the output voltage from the needle break sensor 9 in the range of 0V to 5V is sampled by the A / D converter, the minimum The output voltage is 0.0049V.

  A rotation detector 18, a teaching switch 19, and a sewing machine stop circuit 20 are connected to the microcomputer MC. The rotation detector 18 outputs a rotation pulse signal for each rotation of the sewing machine, and the output timing is when the needle passes through the top dead center. The teaching switch 19 is for operating a basic operation program (calculation means) for teaching, and when the switch 19 is not operated, the basic operation program (determination means) for detecting broken needles is preferentially operated. . The sewing machine stop circuit 20 outputs a sewing machine motor stop signal.

  Next, the control operation in the present embodiment will be described with reference to FIGS. When the device is switched on, as shown in FIG. 4, the needle break confirmation count S is initialized and set to zero (# 1), and the needle break sensor data Y is initialized and set to zero. (# 2). The output voltage of the needle break sensor 9 that has passed through the amplifier circuit 16 is converted by A / D conversion (# 3). Thereby, the first data X is generated. Thereafter, it is compared whether or not the first data X (A / D converted data) is larger than the needle break sensor data Y (# 4), and the first data X is replaced with the needle break sensor data Y only if applicable, and the RAM 14 (# 5). That is, as shown in FIG. 7, when the needle is lowered, the needle break sensor data Y is updated one after another, and the value at the needle bottom dead center (the maximum value of the first data X) remains as the first candidate.

  Then, it is checked whether or not a sewing machine rotation signal from the rotation detector 18 has been input (# 6), and a rotation pulse signal output for each rotation of the sewing machine is confirmed. If the sewing machine rotation signal is not confirmed, the operations from the A / D conversion of the output voltage output from the needle break sensor 9 to the first data X comparison process (# 3 to # 5) are performed again, and the needle break sensor data Y Decide the final candidate. When the sewing machine rotation signal is confirmed, the needle breakage determination reference value Z stored in the EEPROM 15 is read, and it is compared whether or not the needle breakage sensor data Y is smaller than the needle breakage determination reference value Z (# 7). That is, as shown in FIG. 7, it is checked whether or not the needle break sensor data (maximum value of the first data) Y updated when the needle is lowered exceeds the needle break judgment reference value Z.

  If the needle break sensor data Y is larger than the needle break determination reference value Z, it is determined that there is no needle break, and the processing after the start is continued. On the contrary, when the needle break sensor data Y is smaller than the needle break determination reference value Z, it is determined that the needle breaks. However, in the present embodiment, in order to prevent erroneous detection, it is checked whether or not the needle breakage confirmation count S is generated twice consecutively (# 8). When the needle break confirmation count S is the first (initial value 0), 1 is added to the count S (# 9a), and the processing is continued from initialization (# 2) of the needle break sensor data Y. When the needle break confirmation count S is the second time, a sewing machine stop signal is output from the sewing machine stop circuit 20 (# 9b), and the sewing machine motor stops.

  Thereafter, it is checked whether or not the reset switch is turned on (# 10), and the sewing machine motor is stopped until this reset switch is turned on. When it is confirmed that the reset switch is turned on, the sewing machine motor stop signal is cleared (# 11), and the process is continued from the start. That is, after the needle break sensor data Y and the needle break determination reference value Z are compared, the needle break sensor data Y stored in the RAM 14 is initialized.

  Incidentally, when using the needle breakage detecting device according to the present invention, it is desirable to set a needle breakage determination reference value before sewing by teaching or the like. In this embodiment, teaching is operated by a teaching switch 19 attached to the apparatus. As shown in FIG. 5, when the teaching switch is pressed (# 21), the needle break determination reference temporary data α is set to the maximum value by initialization (# 22). Then, the teaching data β is set to zero by initialization (# 23), and the teaching needle number γ is set to zero by initialization (# 24). Then, a teaching lamp (not shown) is turned on (# 25), and the output voltage of the needle break sensor 9 that has passed through the amplifier circuit 16 is converted by A / D conversion (# 26). Thereby, the first data X is calculated.

  It is compared whether or not the first data X (A / D converted data) is larger than the teaching data β (# 27), and the first data X is replaced with the teaching data β and stored in the RAM 14 only when applicable (# 28). ). That is, the teaching data β is updated as necessary, and the maximum value of the first data X is extracted. Then, it is checked whether the teaching needle number γ, that is, the number of stitches after starting teaching has reached 300 stitches (# 29), and if the teaching needle number γ has not yet reached 300 stitches, The operations (# 26 to # 28) from A / D conversion of the output voltage output from the break sensor 9 to the first data X comparison processing are repeated. If a sewing machine rotation signal is input during the operations (# 22 to # 28) from the initialization of the values α, β, and γ to the first data X comparison process, a sewing machine rotation interruption process described later is performed.

  When the teaching needle number γ reaches 300 stitches, a predetermined value is subtracted from the temporary needle breakage determination reference data α (# 30), and the value after subtraction is stored in the EEPROM 15 as the needle breakage determination reference value Z (# 31). . The data stored in the EEPROM 15 is not lost even when the power of the apparatus is turned off, and can be rewritten as necessary. In the present embodiment, the predetermined value subtracted from the needle breakage determination reference provisional data α is 10, and this value corresponds to 0.049 V in terms of voltage. That is, a value that is 0.049V lower than the output voltage corresponding to the final candidate needle break determination reference temporary data α is stored as the needle break determination reference value Z. Thereafter, the teaching lamp is turned off (# 32), and teaching ends. In this embodiment, the teaching needle number γ is set to 300 stitches. However, the teaching needle number γ is not limited to this. For example, the teaching needle number may be 250 stitches or 200 stitches.

  Finally, the sewing machine rotation interruption process will be described. When the sewing machine rotation signal from the rotation detector 18 is input, it is compared whether or not the teaching data (first data maximum value) β is smaller than the needle break determination reference temporary data α (# 41), and teaching is performed only when applicable. The data β is replaced with the needle break determination reference temporary data α and stored in the RAM 14 (# 42). That is, the needle break determination reference provisional data α is updated as necessary, and the minimum value is extracted from the first data maximum value. Then, 1 is added to the teaching needle number γ (# 43), the teaching data β is initialized to zero (# 44), and the sewing machine rotation interruption process is terminated. In the present embodiment, when the sewing machine rotation interruption process (# 41 to # 44) is executed 300 times, the teaching needle number γ confirmation work (# 29) is cleared.

It is the schematic side view explaining the installation location of the detector of the needle | hook breaking detection apparatus of the sewing machine which concerns on this invention. It is explanatory drawing which showed the detection surface of the needle detector. It is a schematic block diagram showing a control system of the detection apparatus. It is the flowchart figure explaining the operation | movement regarding the determination means of the same detection apparatus. It is the flowchart figure explaining the basic operation regarding the calculation means of the same detection apparatus. It is the flowchart figure explaining the sewing machine rotation interruption process of the calculation means. It is the schematic diagram explaining the outline | summary of the needle break detection by the determination means.

Explanation of symbols

9 Needle break sensor (needle detector)
15 EEPROM (memory means)
18 Rotation detector MC Microcomputer X First data Y Needle break sensor data (first data maximum value)
Z Needle breakage judgment reference value α Needle breakage judgment reference provisional data (minimum value)
β Teaching data (first data maximum value)

Claims (2)

A needle detector disposed near the bottom dead center of the needle and a rotation detector that outputs a rotation pulse signal for each rotation of the sewing machine, and detects needle breakage of the sewing machine that is detected during sewing of the sewing machine. In the detection device,
An oscillation circuit for generating a signal with a constant operation clock;
An A / D converter that converts the output voltage of the needle detector based on a signal from the oscillation circuit;
Based on the signal from the oscillation circuit, the output voltage of the needle detector is converted by the A / D converter to extract the maximum value of the first data while generating the first data, and the extraction of the first data maximum value is rotated. When the rotation pulse signal is generated from the rotation detector while repeating until the rotation pulse signal from the detector reaches a predetermined number, the minimum value is extracted from the first data maximum value, and the first data maximum value is extracted. A calculation means for subtracting a predetermined value from the minimum value after completing the repetition to calculate a needle breakage determination reference value;
Storage means for storing the needle breakage determination reference value calculated by the calculation means;
Based on the signal from the oscillation circuit, the output voltage of the needle detector is converted by an A / D converter to extract the maximum value of the first data while generating the first data, and a rotation pulse signal is generated from the rotation detector. When the first data maximum value is smaller than the needle breakage determination reference value by comparing the first data maximum value with the needle breakage determination reference value after the next rotation pulse signal is generated. A needle breakage detection device for a sewing machine, comprising: a determination means for determining.   The sewing machine needle breakage detecting device according to claim 1, wherein the sewing machine motor is stopped when the breakage detection by the judging means is continuously generated at least twice.

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