JPH0312910B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a means for feeding out rollers by means of a stepping motor that rotates in response to a pulse signal generated every predetermined angular rotation of the spindle during one rotation of the spindle. When the sewing speed is higher than the normal sewing speed (high speed), the needle thread feeding device of the sewing machine is configured to continuously feed out the amount of thread set in advance by the setting means from the supply source while the main shaft is rotating. Concerning.

Conventionally, with this type of device, the needle thread of the length necessary to form one stitch is let out at once when the thread take-up is lowering while loosening the needle thread, and it is not let out when the thread take-up is rising while pulling up the needle thread. Since it is an intermittent feeding method, the operating speed of the sewing machine is limited by the response characteristics of the stepping motor that manually controls the feeding means, and the upper thread feeding cannot follow the high speed operation of the sewing machine. This invention aims to eliminate the above-mentioned conventional drawbacks.

Embodiments of the present invention will be described below with reference to the drawings.
1 is a needle bar on which a needle 2 with an upper thread T is fixed at the lower end;
It moves up and down in conjunction with the main shaft (not shown) of the sewing machine. Reference numeral 3 denotes a well-known thread take-up, which supports the needle thread T between the needle thread spool 4 and the needle 2 as a needle thread supply source, rises to pull up the needle thread loop above the throat plate, and descends to take up the needle thread loop. It moves up and down between two predetermined positions in conjunction with the main shaft and in synchronization with the up and down movement of the needle bar 1 so as to allow the upper and lower threads to be captured by the needle bar 1 and fall out of the hook. The thread tightening period corresponds to the rotation angle of the main shaft from when the thread reaches the lower surface of the fabric until the entangled portion is drawn into the fabric. 5 is an outer frame (machine frame) of the sewing machine, a thread hook 6 is fixed to the front wall 5a thereof, and a thread guide groove 7 is formed in the upper wall 5b so as to penetrate into the machine frame.

On the front wall 5a, a drive roller 9 fixed to the output shaft of a stepping motor (hereinafter referred to as motor) 8 is disposed on one side of the path of the upper thread T passing through the thread guide groove 7, and on the other side. A driven roller 10 is disposed at , and both rollers 9 and 10 constitute a feeding means. The driven roller 10 is rotatably supported at the free end of an arm 11 whose base end is rotatably supported on the machine frame, and has an elastic body (not shown) that acts on the arm 11 in the counterclockwise direction in FIG. Due to the acting force of
The outer periphery is always pressed against the outer periphery of the drive roller 9. In the machine frame 5, a pair of clamping plates 12, 13 sandwich the upper thread T between the rollers 9, 10 and the bobbin winder 4.
are arranged facing each other, and one clamping plate 12 is fixed to the movable element of an electromagnetic solenoid (hereinafter referred to as a solenoid) 14, and both clamping plates 12 and 13 are gripped by the upper thread T by energizing and de-energizing the solenoid 14. - Configure to release. And this solenoid 14
is excited in connection with the detection of the rotation angle position of the main shaft corresponding to the thread tightening period by the balance 3 by a detector not shown in the figure, and also the rotation angle of the main shaft corresponding to the non-thread tightening period. They are adapted to be demagnetized in connection with the detected position and constitute a needle thread gripping device.

Note that 15 is a known base tension placed at the rear of the thread guide groove 7, and always provides a constant resistance to the upper thread T that is weaker than the tension of the lower thread.

Next, the electric circuit of this invention will be explained with reference to FIG.

G1 to G4 are AND gate circuits (hereinafter referred to as gates), and I1 and I2 are inverters.

Reference numeral 20 denotes a main shaft pulse generator, which consists of a disk fixed to the main shaft and having a plurality of slits arranged at equal intervals on the same circle, and a sensor placed opposite to the rotation path of the slits, and which generates pulses every time the main shaft rotates by a predetermined angle. A signal is generated in connection with the detection of the slit. A first conversion circuit 21 converts an input signal into a signal with a voltage value corresponding to the frequency and outputs the signal. A second conversion circuit 22 converts an input signal into a signal with a frequency corresponding to the voltage value and outputs the signal. Reference numeral 23 denotes a variable resistor as a first attenuator, and the resistance value is determined in relation to the setting conditions of the setting means that allows setting different sewing conditions by manual operation or based on information recorded electrically or mechanically in advance. change. For example, it may be mechanically linked to the mode of manual operation of any one or all of a manual device for setting the fabric feed pitch, a manual device for setting the swing width of the needle bar 1, and a manual device for setting the fabric thickness. , or related to the information read out from the storage means electrically related to aspects of these manual devices, or one stitch previously recorded in the recording device electrically (ROM) or mechanically (cam) The resistance value changes in relation to each information.

Reference numeral 24 denotes an upper level detector, which consists of a disc fixed to the main shaft and having a notch formed therein corresponding to the rotation angle corresponding to the tension of the needle thread T by the thread take-up 3, and a sensor placed opposite to the rotation path of the notch. During the tension period, a low level signal (hereinafter referred to as L) is output, and during the relaxation period, a high level signal (hereinafter referred to as H) is output. 25 is a pulse edge generating circuit which captures the rising edge of the input and instantaneously generates an H signal. 26
is a counter, which is reset by receiving an H signal at the R terminal. 27 is a second attenuator, which is the first attenuator 2;
Linked to 3. Reference numeral 23 denotes an analog/digital conversion means as a third conversion circuit, which converts the input signal into a binary code corresponding to the voltage value and outputs the binary code. Reference numeral 29 denotes a matching circuit which turns low when the output of the counter 26 and the output of the third conversion circuit 28 match.
generates a signal. Note that VA is a voltage that is adjusted appropriately through a resistor to the power supply voltage, and can be changed.

30 detects whether the rotational speed of the main shaft is high speed above a certain speed or low speed below a certain speed, and opens gate G2 when it is high speed, and opens gate G3 when it is low speed. This is a judgment circuit that controls the opening/closing of G3, and consists of the following multiple elements. That is, 31 and 32 are comparison circuits which generate an L signal when the input voltage at the minus terminal is greater than the input voltage at the plus terminal. 33 is an RS type flip-flop (hereinafter referred to as FF), with L connected to the S terminal.
When a signal is inputted to the Q terminal, an H signal is outputted, and when an L signal is inputted to the R terminal, an L signal is outputted from the Q terminal. Vcc is the power supply voltage, R1~
R3 is a resistance.

The present invention has the above configuration, and its operation will be explained next. When the sewing machine is driven, the iron rod 1 and the balance 3 move up and down in conjunction with the rotation of the main shaft while maintaining a slight phase shift. Furthermore, a signal is output from the main shaft pulse generator 20 every time the main shaft rotates by a predetermined angle, and a signal of L is output from the upper position detector 24 during the tensioning period of the upper thread T by the thread take-up 3.

Therefore, for example, when the sewing machine is driven at a certain speed or lower, that is, when the output voltage of the first conversion circuit 21 is lower than the voltage level at the P1 point, the FF 33 outputs an L signal to the R terminal. Since the signal is input, an L signal (low speed signal) is output from the Q terminal. This closes the gate G2 and cuts off the output of the second conversion circuit 22. On the other hand, since gates G3 and G1 open at the same time as gate G2 closes, the motor 8 is driven by the output of the spindle pulse generator 20 through the motor drive circuit to the first speed corresponding to the driving speed of the sewing machine.
Rotate clockwise as shown in the figure. To describe this in more detail, the counter 26 is connected to the pulse edge generating circuit 25.
The gate G is controlled by the signal output from the spindle pulse generator 20 until it is reset by the signal
As the motor 8 rotates via G4, G3, and G1, the signal is counted by the counter 26, and when the counted value matches the output code of the third conversion circuit 28, the output of the matching circuit 29 is output. As a result, gate G4 is closed and motor 8 is stopped. Therefore, for example, assuming that the number of signals oscillated from the spindle pulse generator 20 during one reciprocating movement of the balance 3 is 100 pulses, the condition for matching the outputs of the counter 26 and the third conversion circuit 28 is as follows: The closing condition for the gate G4 is that the value of the counter 26 can be set to a maximum of 100 and any value below it by setting the second attenuator 27.
For example, if the value is set to 20, the motor 8 rotates for 20 pulses from the start of relaxing the needle thread T by the thread take-up lever 3, then stops, and this process is repeated every time the sewing machine forms one stitch.

Therefore, the feeding of the upper thread (rotation of the stepping motor) is continuous if the number of pulses set by the second attenuator 27 is 100 in the case of the above embodiment, and is intermittent if it is less than 100.

Contrary to the above, when the sewing machine is driven at a certain speed or higher, that is, when the output voltage of the first conversion circuit 21 is higher than the voltage level at point P2,
Since an L signal is input to the S terminal of the FF33, an H signal (high speed signal) is output from the Q terminal. As a result, gate G2 opens at the same time as gate G3 closes, so motor 8 rotates clockwise in FIG. 1 via damper 23 at a speed corresponding to the driving speed of the sewing machine. If the number of pulses output from the spindle pulse generator 20 during one revolution of the spindle is 100, then if the attenuation rate of the first attenuator 23 is 1/2, then
The number of pulses output from the second conversion circuit 22 is 50, and the motor 8 rotates in response to these 50 pulses during one rotation of the main shaft. Therefore, the amount of yarn let out in this case is 1/2 of the maximum amount that can be let out by this letting out device. Further, if the attenuation rate of the first attenuator 23 is 1/4, the number of pulses output from the second conversion circuit 22 will be 25, and the yarn payout amount will be further 1/2 of the above. In this way, even if the sewing machine is driven at the same speed, if the sewing conditions such as cloth feed pitch, needle amplitude, and cloth thickness are different, the attenuation rate of the attenuator 23 will be different, and the rotational speed of the motor 8 will also be different. It becomes ivy.

When the motor 8 rotates in this manner, the roller 9
rotates in the clockwise direction in FIG.
With the cooperation of the above, the upper thread is continuously paid out from the bobbin spool 4 toward the thread take-up 3 at a speed corresponding to its rotation speed.

Note that during the thread tightening period by the thread take-up lever 3, the electromagnetic solenoid 14 is energized so that the needle thread T is held by a pair of clamping plates 12 and 13 and is prevented from being fed out from the bobbin winder 4. Upper thread T between rollers 9, 10 and a pair of clamping plates 12, 13
Microscopically, the thread is stretched slightly, but this thread tightening period is only a small angle when converted to the rotation angle of the main shaft, and it is only a moment in time, so it has no effect on the sewing.

This invention uses a stepping motor that rotates in response to a pulse signal generated every predetermined angular rotation of the spindle during one rotation of the spindle, and a feeding means that includes a roller that rotates in conjunction with the stepping motor. This is because the amount of thread required for each stitch formation set in advance by the setting means is continuously fed out from the supply source during the rotation period when the main shaft is rotating at a high speed higher than the normal sewing speed. Even a stepping motor with poor responsiveness can follow the high-speed operation of the sewing machine, thereby increasing the operating speed of the sewing machine, improving sewing efficiency, and reducing the cost of this device.

Note that FIG. 3 shows another embodiment of the first conversion circuit 21 in this embodiment, and the same elements as in this embodiment are given the same numbers. FIG. 4 is a time chart of FIG. 3. That is, regarding the configuration, 4
The first pulse edge generation circuit of 0 detects changes in the signal of the main shaft pulse generator 20 and instantaneously generates an H signal. A second pulse edge generating circuit 41 catches the falling edge of the signal from the generating circuit 40 and instantaneously generates an H signal. 42 is a reference pulse generator that always generates a signal at a constant frequency. 4
3 is a counter which clears the contents upon receiving an H signal at its R terminal. 44 is a latch circuit, and H is connected to the R terminal.
It receives the signal and outputs the input state at that time. 4
5 is a digital/analog converter, input (numeric value)
generates a voltage at a level corresponding to G5~G7
is a gate, and I5 is an inverter.

Regarding the operation shown in FIG. 3, when the sewing machine is driven, a signal is generated from the main shaft pulse generator every time the main shaft rotates by a predetermined angle. On the other hand, during the period from the rise to the fall of the signal or from the fall to the rise of the signal, the output signal of the reference pulse generator 42 is counted by the counter 43 via the gate G6 and the inder I5, and the signal is The latch circuit 44 is latched via the gate G7 by the signal from the generating circuit 41 related to the change in the voltage, and the voltage is at a level corresponding to the count value of the counter 43 at that time (when the count value is large, the voltage is at a lower level than when it is small). ) is output from the converter 45.

Further, FIGS. 5 and 6 show separate other embodiments corresponding to FIG. 1, and the same elements as in this embodiment are given the same numbers. That is, FIG. 5 shows the solenoid 14 and the clamping plate 1 as an upper thread gripping device.
2 and 13 are rollers 9 and 1 as feeding means.
0 in the direction in which the upper thread T is fed out, and the clamping plate 1
2 and 13 grip the upper and lower T, thereby preventing a large load from being applied to the motor 8 when tightening the stitches, and preventing the needle thread T from being unwound excessively.

In addition, FIG. 6 shows an example in which the feeding means of this embodiment is replaced with other elements, 50 is a spinning wheel fixed to the output shaft of the motor 8, around the outer periphery of which the upper thread T can be wound; , 52 are cloth-pulling rollers that rotate in conjunction with the main shaft. The timing of energizing and de-energizing the solenoid 14 is the same as in this embodiment. Then, when the motor rotates in proportion to the rotational speed of the main shaft, the upper thread T wound around the spinning wheel 50 is paid out toward the thread take-up lever 3. At the same time, the same amount of thread is paid out by the spinning wheel 50, and the needle thread T is pulled out. roller 51,
52, the upper thread T is further fed out to the side of the thread take-up lever 3, so that the upper thread T is always wound around the spinning wheel 50 with a constant tension, so that an amount of thread proportional to the rotation angle of the spinning wheel 50 is reliably paid out. This is what I did.

Furthermore, in this embodiment, if the pressing force of the rollers 9 and 10 is strengthened and the motor 8 with a large torque is used to prevent the needle thread T from being excessively paid out when the thread thread take-up is tightened by the thread take-up lever 3, it is possible to 12,
13 and solenoid 14 may be omitted.

Further, in this embodiment, the stepping motor 8 is used as the drive source for the feeding means, but a servo motor may also be used. In this case, the second conversion circuit 22 in the embodiment shown in FIG. 2 is not required, and the output of the amplifier circuit 23 is input to the servo motor via a comparison circuit (not shown), and the position of the servo motor is detected. The configuration may be such that the output of the potentiometer is fed back to the comparison circuit for control.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the main parts, Fig. 2 is a block diagram of the electric circuit, Fig. 3 is another embodiment of the first conversion circuit,
FIG. 4 is a time chart of FIG. 3, and FIGS. 5 and 6 are other embodiments corresponding to FIG. 1. 3 is a balance, 8 is a stepping motor, 9, 10
is a roller as a feeding means, 20 is (main shaft)
The pulse generators 21, 22, and 23 are a first conversion circuit, a second conversion circuit, and an attenuator as conversion circuits.

Claims (1)

[Scope of Claims] 1. A main shaft that is linked to a drive source and supported on a machine frame so as to be rotatable about a fixed axis; and a main shaft that is linked to the main shaft and generates a pulse signal every time the main shaft rotates by a predetermined angle during its entire rotation period. A conversion device that consists of a pulse generator 20, a frequency/voltage conversion circuit, a variable resistor, and a voltage/frequency conversion circuit, and changes and outputs the frequency of pulse generator signal generation at a ratio related to the set resistance value of the variable resistor. circuit 21,
23, 22, a setting means for changing the resistance value of the variable resistor, a stepping motor 8 that is related to the output signal of the conversion circuit and rotates in one direction at a speed corresponding to the frequency of the signal output, and an upper thread. a thread take-up 3 that reciprocates in conjunction with the main shaft to support the needle thread and tighten or loosen the needle thread in connection with stitch formation; and feeding means 9 and 10 rotatably supported on the machine frame, and when the main shaft is rotating at a high speed higher than the normal sewing speed, the yarn amount set by the setting means is continuously fed from the supply source during the rotation period. An upper thread supply device for a sewing machine, characterized in that the needle thread is fed out in a targeted manner.