JPS6027313B2 - sewing machine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sewing machine control device configured to perform counting control of the number of stitches.

Generally, when controlling the number of stitches in a conventional sewing machine control device, a method has been adopted in which, for example, only a position signal indicating the needle down position is input, and the number of pulses is simply counted.

In this conventional method, in the process of decelerating the sewing machine, once driving it at a low speed, and then stopping it at a predetermined position, for example, the speed response of the electric motor or the pulley between the electric motor and the sewing machine head must be adjusted. Due to a time delay when switching between deceleration and acceleration due to loosening of the intervening belt, the motor may stop before reaching the low-speed drive state and repeat reverse and forward rotation two to three times. If this situation overlaps with the counting position signal, two or three position signal pulses will be generated due to the reverse rotation and forward rotation, even though the positions are the same. This has a fatal drawback in that the number of stitches generated is counted and the finished stitches are fewer than the set number of stitches.

The object of the present invention is to eliminate such drawbacks as mentioned above,
The object of the present invention is to realize a sewing machine control device capable of more accurate counting than that of a secondary mechanism.

The configuration and operation of an industrial sewing machine as an example to which the present invention is applied will be described below with reference to the block diagram shown in FIG.

First, when the pedal of the sewing machine is depressed, a pedal depression signal VPo is output from the pedal depression detection circuit 1 and inputted to the needle localization layer stop circuit 2, and its output VB drives the speed control circuit 3, while setting the speed. A speed setting signal Vs is input from the circuit 4 to the speed control circuit 3 according to the amount of pedal depression, and the output VcL attracts the clutch coil 5, and the rotational force of the electric motor is applied to the clutch coil (not shown).
It is further transmitted to the sewing machine head via the pulley belt, and the sewing machine begins to accelerate.

On the other hand, the rotational speed is detected by a speed generator (not shown), and an actual speed signal VT is inputted to the speed control circuit 3 through the speed detection circuit 6. This speed control circuit 3 outputs V when the actual speed signal VT becomes larger than the speed setting signal Vs.
The brake coil 7 is attracted by the BR to reduce the speed, and in the opposite case, the clutch coil 5 is attracted and the speed is increased to maintain a constant speed depending on the amount of pedal depression. On the other hand, the depression signal VP8 is input to the counting circuit 8, and serves as a detection signal of a first position (hereinafter referred to as position 1) corresponding to the needle lower layer, that is, a position 1 detection signal VN from the position 1 detection circuit 9. Start counting. Counting circuit 8
When the sewing machine finishes counting the number of stitches set by the stitch number setting circuit 10, it outputs a signal V8, and this signal V8 blocks the speed setting signal Vs and acts to set a low speed, and the sewing machine operates at a low speed. Move on to driving. In this state, the counting circuit 8 outputs the signal VTR in response to the position 1 detection signal V skin, attracts the thread cutting solenoid 11, and the sewing machine starts thread cutting. Furthermore, when the detection signal of a second position (hereinafter referred to as position 2) corresponding to the upper position of the needle, that is, the position 2 detection signal VNU from the position 2 detection circuit 12, is input to the counting circuit 8, the signal VTR is turned off. Then, the thread trimming solenoid 11 is turned off, the signal VBU is outputted, and the sewing machine is stopped at position 2. Here, during the above-mentioned sewing operation, the signal V is output from the counting circuit 8 in the interval set by the stitch number setting circuit 10.
8T is output, the reverse stitch solenoid 13 is sucked, and reverse stitching is performed.

Further, when the pedal is placed in the neutral position during the sewing operation, the speed setting signal Vs is first turned off, the speed setting circuit 3 enters a low speed setting state, and the sewing machine shifts to low speed operation. Further, when the pedal is placed in the neutral position, the needle position stop circuit 2 outputs a depression signal VP. When the position 1 detection signal VNo is detected, the output V8 acts to cause the motor to stop at the position 1. The operation of the sewing machine as an example to which the present invention is applied has been described above, and an explanation will be added below according to the time chart of FIG.

Here, an example will be shown in which the pedal is turned to neutral twice from a fully depressed state. a is the time course of the sewing machine rotation speed, b is the depression signal VPo, c is the position detection signal VNo, d is the position 2 detection signal VNU, e is the reverse stitch solenoid suction signal V8T, and f is the thread trimming solenoid suction signal V, R, respectively. show.

First, when the pedal is depressed, the sewing machine starts operating at a speed corresponding to the amount of pedal depression from low speed NP to medium speed NBT, and at the same time starts counting position 1 detection signals.

Next, when the pedal is placed in the neutral position, the speed changes from medium speed NBT to low speed NP6, and stops at position 1 when the position 1 detection signal V skin is detected. When the pedal is depressed again, the speed becomes medium speed N8T and the vehicle stops at position 1 when the vehicle is brought to neutral.

Here, when the preset number of stitches X is counted during the medium speed Nbr operation, the reverse stitch solenoid is sucked and the sewing machine switches from normal stitching to reverse stitching. When the pedal is depressed again, the sewing machine enters the midway NBT operation state, and when the set number of stitches (x+Y) is sewn, it automatically switches to low speed NPa operation, and then the position 1 detection signal V side When this is detected, the reverse stitch solenoid is turned off and the thread trimming solenoid is suctioned.

From this state, the next position 2 detection signal V skin is detected,
The sewing machine stops at position 2 and finishes the preset normal stitch x and reverse stitch Y sewing. Sewing is performed in this manner, and the finished stitch is shown in FIG.

An example of the operation of a commonly used sewing machine has been described above, and the gist of the present invention and its application will be described below.

In Fig. 2, the dashed line section marked with an asterisk (*) indicates the process from midway N8T operation to Calendar 1 stop.The state of this part is shown in Fig. 4 with a wider time axis, and the following explanation will be given according to the same figure. .

If the response of the electric motor is poor, or if the belt connecting the electric motor and the sewing machine head is loose, the rotation speed should be changed from medium speed NBT to low speed NP as shown in the figure.
When switching to A, the rotation is temporarily reversed.

Here, if the above-mentioned normal rotation is switched to reverse rotation immediately after passing position 1, the position 1 detection signal V side will be changed again due to the reverse rotation even though it has not actually made one rotation. It happens like this.

Therefore, if only such position 1 detection signal VND is simply counted, the finished sewing will be one stitch less than the set number of stitches. The present invention eliminates the drawbacks of the prior art described above and provides a sewing machine control device that accurately controls the number of stitches, and will be described with reference to FIGS. 5 and 6 showing specific embodiments. . FIG. 5 is a flowchart showing the first invention.

Check the detection signal VNo indicating position 1 by the counting means,
Next, it is confirmed that the signal has ended, and the number of stitches is counted by one. Next, when the inhibiting means confirms the detection signal VNo indicating position 2, the original loop is returned to a state where the next one-count counting is possible. In other words, after counting position 1 by one count by the counting means, the next count is prohibited until position 2 is confirmed by the inhibiting means. In this example, position 1 is the needle lower straight, position 2 is
Since the needle position calendar is used as the needle position, there is a gap of approximately 180 degrees between these two positions, and generally speaking, the sewing machine reversal angle due to belt loosening or vibration is at worst 100 degrees.
Since it is as follows, the above-mentioned problem can be eliminated with sufficient margin. Naturally, the present invention uses the needle sublayer as position 1, . Not limited to those that adopt the needle upper layer as position 2,
It is effective to use the upper layer of the needle as position 1 and the lower layer of the needle as position 2, or to use positions unrelated to the upper and lower positions of the needle as positions 1 and 2. 6th
The figure is a flowchart showing a second embodiment of the invention.

Check the detection signal VNo indicating position 1 by the counting means,
Next, it is confirmed that the signal has ended, and the number of stitches is counted by one. Then, when a delay time, for example, 5 hS, elapses due to the inhibiting means, the loop returns to the original state, and the next 1 count becomes possible. In other words, after the counting means counts position 1 by one count, the inhibiting means prohibits the next count for a certain period of time. For example, assuming that the average rotation speed at this point is 30 pm, the time required for one rotation is 20 plates S, and after confirming position 1, the next position 1 signal can be obtained extremely quickly, for example 5 pieces S. However, this is based on the idea that this signal is determined to be an erroneous signal due to belt vibration, etc., and this signal is to be eliminated.
Naturally, the present invention is not limited to employing the needle lower layer as position 1, but is also effective even if the needle upper layer or a position unrelated to the needle upper and lower positions is employed. Application of the present invention as described above can be easily implemented by logic, electronic components such as flip-flops and counters, or by a microcomputer.

Although the above description has focused on the process of switching from medium speed to low speed, this method is also effective as a countermeasure against chattering when position detection is performed using a switch, for example.

The present invention aims to provide a sewing machine control device that includes a function to count the number of stitches, and is intended to be used to control instantaneous sewing machines caused by, for example, poor responsiveness of the electric motor or vibration of a belt connecting the electric motor and the sewing machine head. sewing machine 1 due to reverse rotation or chattering of the reed switch for needle position detection.
Even if position signals are generated multiple times due to rotation, by accurately counting one rotation of the sewing machine as one count, it is possible to sew the preset number of stitches accurately, which is extremely effective. It is something.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a configuration as an example to which the present invention is applied, FIG. 2 a to f are time charts showing operations, FIG. 5 and 6 are flowcharts showing the counting method of the present invention. 8... Counting circuit, 9, 12... Position detection circuit. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. An electric motor, a sewing machine head driven by the electric motor, and a needle position detector connected to the sewing machine head and generating a first position signal indicating the needle down position, etc., and a second position signal indicating the needle up position, etc. a counting means for counting the first position signal; and a prohibiting means for prohibiting counting by the counting means until the second position signal is detected after the counting by the counting means has been performed. Sewing machine control device.