JPH0632727B2 - Thread restraint actuator for sewing machine and its control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread restraining actuator for a sewing machine, and a control device for the same, in which a piezoelectric element is used to restrain a thread of an automatic thread tension device of an industrial sewing machine.

[Prior Art] In the domestic sewing machine, the present applicant has proposed an automatic thread tensioning device for restraining the upper thread of a section of the sewing machine that makes one revolution by a solenoid so that the amount of upper thread fed out is always constant. There is.

[Problems to be Solved by the Invention] However, since the response speed of the solenoid is slow, there is a problem that the solenoid cannot be applied to the thread tension device of the industrial sewing machine when the speed becomes high as in the industrial sewing machine.

The present invention, while taking advantage of the high-speed response of the laminated piezoelectric element and the advantage of generating a large force, adopts a mechanism for magnifying the displacement as a countermeasure against the disadvantage of minute displacement, and at the same time operates the magnifying mechanism at high speed. As a measure to suppress the occurrence of mechanical vibration that disturbs the vibration, firstly, mechanical vibration-proof measures are adopted by supporting the expansion mechanism with a hinge spring and by providing a preload spring, and secondly, in the operating characteristics of these expansion mechanisms. It is an object of the present invention to provide an actuator having a good high-speed response and a strong gripping force by adopting an electric anti-vibration measure for controlling energization of a piezoelectric element so as to match.

[Means for Solving the Problem] In order to achieve the above object, in the thread restraining actuator for a sewing machine of the present invention, two laminated piezoelectric elements, one end of which is fixed to the inner surface of the frame, are arranged substantially parallel to each other inside the frame. Then, the other end of the laminated piezoelectric element is fixed to one end of a drive shaft slidably mounted on the frame, one end of a hinge spring is fixed to the frame in the vicinity of the drive shaft, and the other end of the hinge spring is L-shaped. By fixing each to the drive arm, contacting the other end of the drive shaft, fixing one end of each preload spring to the opposite side surfaces of the frame, and contacting the other end of this preload spring to the end of the drive arm, The drive arm is rotated to the drive shaft side to strengthen the contact between the drive arm and the drive shaft, one end of the expansion lever is fixed to the drive arm, and the thread restraint portion provided at the other end of the expansion lever is provided oppositely. Is something .

Further, in the control device for the sewing machine thread restraint actuator of the present invention, a charging / discharging control circuit that controls charging / discharging of the piezoelectric element, and a voltage detection circuit that detects a voltage across the piezoelectric element,
It consists of a voltage setting circuit that sets the voltage applied to the charge and discharge control circuit, and sets the voltage applied from the charge and discharge control circuit to the piezoelectric element according to the curve along the rising curve of the displacement magnifying mechanism connected to the piezoelectric element. At the same time, after detecting a predetermined voltage with the voltage detection circuit, by applying a voltage difference between the voltage corresponding to the voltage detected by the voltage detection circuit and the voltage of the voltage setting circuit to the charge / discharge control circuit, The control is performed so that the inflow current that supplements the self-discharge is limited.

[Operation] When a voltage is applied to the piezoelectric element of the thread-constraining actuator for a sewing machine configured as described above, the laminated piezoelectric element pushes up the drive shaft, and the hinge spring is used as a fulcrum on the drive arm that is in pressure contact with the tip of the drive shaft. As a result, a rotation moment acts, and the left and right expansion levers press the threads against each other to restrain them. In addition, the preload spring and the drive arm, and the drive arm and the drive shaft are pressed against each other and move like an integral body at the time of operation, thereby suppressing the occurrence of fretting phenomenon at each pressing portion. In addition, the drive shaft is guided by a hole drilled in the frame,
Only the compressive stress acts on the piezoelectric element, and the disadvantage of the piezoelectric element, which is weak in tensile force, is eliminated.

Also, in order that the rising curve of the voltage of the piezoelectric element follows the rising curve of the displacement magnifying mechanism of the thread restraining actuator for the sewing machine, the rising curve of the voltage of the piezoelectric element is adjusted to the slope by the controller of the sewing thread restraining actuator for the sewing machine. After setting, when the voltage detection circuit detects that the applied voltage of the piezoelectric element has reached a predetermined voltage, by limiting the inflow current to supplement the self-discharge of the piezoelectric element and maintaining the binding force of the binding actuator, It is possible to suppress displacement overshoot and residual vibration of the piezoelectric element.

[Examples] Examples will be described with reference to the drawings. The rectangular frame 1 is provided with a rectangular penetrating space 2, one end of each of the laminated piezoelectric elements 3 and 4 is fixed to one side of this space 2, and the laminated piezoelectric elements 3 and 4 are provided substantially in parallel. Further, on the opposite side of the space 2, the through hole 5 is provided outside from the space 2.
6 are provided, and drive shafts 7, 6 are provided in the through holes 5, 6, respectively.
8 is slidably mounted, and the drive shafts 7, 8 are in contact with the other ends of the laminated piezoelectric elements 3, 4. Drive shaft 7, 8
One end of the hinge springs 9 and 10 is fixed to the frame 1 on the side of, and the other ends of the hinge springs 9 and 10 are fixed to substantially the center of the linear portions of the L-shaped drive arms 11 and 12, A part of 12 is brought into contact with the drive shafts 7 and 8. Also,
One ends of the preload springs 13 and 14 are fixed to the side portions of the frame 1 by screws 17 and 18 by pressing plates 15 and 16, respectively, and the other ends of the preload springs 13 and 14 are ends of bent portions of the drive arms 11 and 12, respectively. It is configured to press the part. In the drive arms 11 and 12,
One end of each of the expansion levers 19 and 20 extending in contact with the frame 1 is fixed to the lower part of the drawing, and the thread restraining portion 1 is attached to the other end.
9'and 20 'are provided. Further, a lever guide is provided on the frame 1 near the thread restraining portions 19 ', 20' of the expansion levers 19, 20.
21 are provided.

In the thread-constraining actuator for a sewing machine of the present embodiment configured as described above, when a voltage is applied to the laminated piezoelectric elements 3 and 4, the laminated piezoelectric elements 3 and 4 push up the drive shafts 7 and 8, respectively, and the drive shaft 7 is formed. , Drive arm 1 in pressure contact with the tips of 8
A rotation moment acts on the hinge springs 1 and 12 with the hinge springs 9 and 10 as fulcrums, and the yarns are clamped and restrained by the yarn restraining portions 19 ′ and 20 ′ of the left and right enlargement levers 19 and 20. Also, the preload springs 13, 1
Since the 4 presses the drive arms 11 and 12, the preload springs 13 and 14 and the drive arms 11 and 12, or the drive arms 11 and 12 and the drive shafts 7 and 8 are pressed against each other, so that they are integrally formed during the operation. By moving, the occurrence of fretting phenomenon at each pressure contact part is suppressed. Further, the drive shafts 7 and 8 are guided by the through holes 5 and 6 formed in the frame 1, and only the compressive stress acts on the laminated piezoelectric elements 3 and 4, which is weak against the tensile force which is a defect of the laminated piezoelectric elements 3 and 4. The disadvantages are removed.

As the control device for controlling the current to the laminated piezoelectric elements 3 and 4 of the thread restraining actuator for the sewing machine of the above embodiment,
As shown in the figure, the subtraction circuit 23 is connected to the output terminal of the voltage setting circuit 22.
A charge / discharge control circuit 24 is connected through the charge / discharge control circuit 24, and the output terminal of the charge / discharge control circuit 24 is connected in parallel with the stacked piezoelectric element 25 of the stacked piezoelectric element 3 or 4 and the voltage detection circuit 26. The output is connected to the subtraction circuit 23.

In the control device configured as described above, the charge / discharge control circuit 24 has a voltage rising curve to the laminated piezoelectric element 25 as shown by a solid line A in FIG. 3 so as to follow the rising curve of the displacement magnifying mechanism.
Supply voltage to the laminated piezoelectric element 25. Then, when the voltage detection circuit 26 detects that the voltage across the laminated piezoelectric element 25 has reached a predetermined voltage, the voltage from the voltage setting circuit 22 is subtracted to supplement the self-discharge of the laminated piezoelectric element 25. Enlarged levers 19 and 20 of thread restraint actuator
The yarn restraining portions 19 'and 20' are configured to maintain the yarn restraining force.

Thus, the voltage rising curve to the laminated piezoelectric element 25,
Along the rising curve of the displacement magnifying mechanism, and when the pressure detection circuit 26 detects that the voltage across the laminated piezoelectric element 25 has reached a predetermined voltage, the voltage from the voltage setting circuit 22 is subtracted, and the laminated By limiting the inflow current to supplement the self-discharge of the piezoelectric element 25, overshoot and residual vibration can be suppressed as shown by the dotted line B in FIG.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, a laminated piezoelectric element is used as a thread restraining actuator for a sewing machine, and a mechanism for enlarging the displacement of the laminated piezoelectric element and an anti-vibration mechanism for the enlarging mechanism. As a mechanical mechanism, the expansion mechanism is mechanically supported by a hinge spring, and a preload spring is used to suppress the vibration of the expansion mechanism, that is, the occurrence of the fretting phenomenon. We succeeded in drastically reducing the vibration of the enlarging mechanism, that is, the overshoot of the displacement of the enlarging mechanism and the residual vibration by adopting the energization control of the piezoelectric element that matches the operating characteristics, which has a good high-speed response and a strong gripping force. An actuator can be obtained, and like a sewing machine, the operation is stopped several thousands of times / minute and the thread under tension is surely grasped. There is an effect that you can stop holding.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a thread restraining actuator for a sewing machine according to an embodiment of the present invention. (A) is a side view, (b) is a partially cutaway front view, and FIG. 2 is a sewing machine thread restraining actuator. FIG. 3 is a block diagram of the control device, and FIG. 3 is a diagram showing a displacement waveform when a voltage of a piezoelectric element driven by the control device of FIG. 2 is applied. 1 ... Frame, 2 ... Space, 3, 4 ... Multilayer piezoelectric element, 5, 6 ... Through hole, 7, 8 ... Drive shaft, 9, 10 ...
Hinge springs, 11, 12 ... L-shaped drive arms, 13, 14 ... Preload springs, 15, 16 ... Holding plates, 17, 18 ... Screws, 19, 20 ... Enlargement levers, 19 ', 20' ...... Yarn restraint section, 21 ...... Lever guide, 22 ...... Voltage setting circuit, 23 …… Subtraction circuit, 24 …… Charging and discharging control circuit, 25 …… Multilayer piezoelectric element, 26 …… Voltage detection circuit.

Claims (2)

[Claims] 1. Two laminated piezoelectric elements arranged in parallel so that one end is fixed to a frame and the other end abuts on one end of a drive shaft slidably mounted on the frame, and a vicinity of the drive shaft. A hinge spring having one end fixed to the frame, a drive arm supported by the other end of the hinge spring, rotated by the bending of the hinge spring, and arranged to face the other end of the drive shaft. And an enlarging lever that allows a thread restraining portion provided at one end to be brought into contact with and separated from the driven arm when rotating, and the driving arm so that the driving arm presses the driving shaft and the laminated piezoelectric element about the hinge spring. A thread restraining actuator for a sewing machine, comprising: a preload spring that applies an elastic force; 2. The movement of the laminated piezoelectric element is acted on an enlargement lever which is rotated by the bending of the hinge spring so that the yarn restraining portion can be brought into contact with and separated from the enlargement lever, and the enlargement lever presses the laminated piezoelectric element around the hinge spring. In a thread constraining actuator for a sewing machine including a preload spring that biases elastic force, a charge / discharge control circuit that controls charge / discharge of the laminated piezoelectric element, and a voltage detection circuit that detects a voltage across the piezoelectric element. A voltage setting circuit for setting a voltage applied to the charge / discharge control circuit, wherein the voltage applied from the charge / discharge control circuit to the piezoelectric element is changed along a rising curve of the expansion lever connected to the piezoelectric element. Set to a rising curve, and after detecting a predetermined voltage by the voltage detection circuit, the voltage detected by the voltage detection circuit and the voltage of the voltage setting circuit Of the thread restraining actuator for the sewing machine, which controls to apply the differential voltage of 1. to the charge / discharge control circuit.