JPH11197948A - Wire supply device of wire-electric discharge machining apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire feed device by which a wire of a wire-electric discharge machining apparatus can be supplied with good follow-up performance at a low cost, the residual wire amount of a wire supply reel is considered, and a rotary variable resistor can be used. SOLUTION: In a motor control system using a resistance value, stop and reverse signals for a motor 19 are output within a resistance value of an inoperative range of speed control, and at the time of rewinding, the wire residual amount is converted to a shaft angle amount of a rotary variable resistor 17, and according to a resistance value of the rotary variable resistor 17 corresponding to the shaft angle amount, the speed of the motor 19 for driving a wire supply bobbin 1 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a wire feeding device in a wire electric discharge machine.

[0002]

2. Description of the Related Art An apparatus for supplying a wire to a wire electric discharge machine is disclosed in Japanese Patent Application Laid-Open Nos. 5-69236 and 7-29.
No. 0321 and the like, and a device for changing the wire supply speed according to the wire tension is disclosed in JP-A-61-26.
3572.

A summary of the technical contents described in Japanese Patent Application Laid-Open No. 61-263572 is to control the wire feeding speed by interlocking a potentiometer with a tension detecting mechanism corresponding to a so-called dancer roller that changes an angle according to the wire tension. These technologies are widely used for supplying wires to wire electric discharge machines, controlling the speed of feeding and winding of fiber or textile intermediate products or other filament products in the textile industry, and adjusting tension. Technology.

[0004] Japanese Patent Application Laid-Open No. 5-69236 discloses that a wire feeder of a wire electric discharge machine uses a motor for driving a wire feed bobbin to displace a dancer roller due to a change in wire tension. This is a technology of a wire supply device that is controlled as a structure that applies a brake in a rewinding direction in addition to a feeding direction.

[0005] The summary of the technical contents described in Japanese Patent Application Laid-Open No. 7-290321 is that the displacement angle of a dancer roller is taken as an increase or decrease from a reference angle, and the displacement angle is directly connected to a potentiometer, so that wire feeding and wire feeding are performed. This is a technique of a wire feeding device for a wire electric discharge machine that controls a rewind speed, and a limit switch is provided below a position where a dancer roller is located to regulate the speed control of the reverse rotation of the motor.

[0006]

Although the technology for supplying wires to a wire electric discharge machine has been considerably improved by incorporating the above-mentioned prior art, in order to provide a more inexpensive wire supply device, the wire feeding device is inexpensive compared to a potentiometer. If the rotary variable resistor can be used to control the stop and reverse rotation of the drive motor of the wire supply bobbin, the total cost of the wire supply device can be reduced.

In order to reduce the frequency of wire supply bobbin replacement as much as possible, there is an increasing tendency to use a wire supply bobbin with a larger wire winding amount by placing a wire supply device outside the electric discharge machine. When the wire is fully wound on the supply bobbin and when the wire is almost empty, there is a need to further improve the followability of the speed control of rewinding.

[0008]

As a result of intensive studies, the present inventor has found that when the displacement angle of the dancer roller from the reference position is detected by the first rotary variable resistor, the rotation of the wire supply bobbin in the feeding direction is controlled. The stop signal and the rewind signal to the speed control device of the motor, which is the power, are transmitted to the camshaft at the angular position of the swing which is directly connected to the rotary variable resistor corresponding to the range of the inoperable resistance value of the speed control device. In addition, a means for solving the above-mentioned problem by controlling the motor by installing a limit switch has been found.

The "rotary variable resistor" referred to here is a variable resistor generally called a volume, whose resistance value changes according to the rotation angle of the shaft. It is preferable that the resistance values have a linear relationship in practicing the present invention. A potentiometer is also a kind of rotary variable resistor, but it can be operated at a precise relationship between the resistance value and the rotation angle and at 360 degrees or more (one rotation or more).
It is more expensive than a normal rotary variable resistor.

[0010] The "range of the resistance value at which the speed control device does not operate" as used herein refers to a speed setting variable resistor (a rotary type variable resistor) for a commonly used AC induction motor speed control device. When the resistance value and the rotation speed of the motor are represented in a graph, as shown in FIG. 3, the resistance value ranges from zero to a certain value at which the rotation of the motor does not start. The range of the resistance value differs depending on the type of motor and the speed control device. That is, there are a range of resistance values that are substantially linearly proportional to the rotation speed of the motor according to the resistance value, and a range of resistance values that cannot be driven by the motor. According to the present invention, when the dancer roller is lowered from a certain position, the resistance value of the first rotary variable resistor associated therewith is set so as to fall within a range in which the speed control device does not operate. At each position corresponding to the displacement angle position according to the two positions where the dancer roller is further lowered within the range of operation,
If a cam and a limit switch are set on the swinging rotation shaft of the dancer roller so as to generate a signal for stopping the motor and for rotating the motor in the reverse direction, the rotation (forward) is performed when the first rotary variable resistor is used. In addition to the speed control in the direction, it is possible to control the start, stop, and rewind of the feeding.

Further, the present inventor cannot control the rewind speed by the dancer roller in the present invention when rewinding the wire (because the dancer roller is already lower than the control range). When rewinding the wire, the remaining amount of wire in the wire supply bobbin is detected by using the second rotary variable resistor, and it is found effective to control the rotation speed of the motor, which is the power, according to the remaining amount of wire. Was.

As means for detecting the remaining wire winding amount of the wire supply bobbin, the tip of a bar attached with a roller which rotates and comes into contact with the wire winding surface of the wire supply bobbin is provided with the axis of the rotary variable resistor as a fulcrum. Should be
The change in the winding diameter that changes according to the remaining amount of the wire may correspond to the change in the resistance value.

The motor for driving the supply bobbin is preferably an AC induction motor that is reversible (reverse rotation possible) and has an electromagnetic brake in consideration of the balance between performance and price.

The motor control device (including stop, forward rotation, and reverse rotation in addition to speed control) can be applied by a speed control device called a speed control unit or a speed control pack provided by a motor maker. The control device is not limited as long as it has the same function.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 1 is a configuration diagram showing a wire electrode supply device according to one embodiment of the present invention. In this wire supply device, a wire 2 wound around a wire supply bobbin 1 is routed by a plurality of guide rollers 3 so as to lift a dancer roller 4, and supplies the wire to an electric discharge machine main body (not shown). The dancer roller 4 is attached to one end of a bar 5, and the other end of the bar 5 is attached to a fulcrum rotation shaft 6 in a direction perpendicular to an axis serving as a fulcrum, and the bar 5 and the dancer roller 4 are integrally formed as a fulcrum rotation shaft 6. Swing around the fulcrum.
The fulcrum rotary shaft 6 is supported by a bearing (not shown) such as a bearing. Further, a cam 7 for operating a stop signal limit switch (not shown), a cam 71 for operating a reverse rotation signal limit switch (not shown), and a gear 8 are fixed to the fulcrum rotary shaft 6.

When machining of the electric discharge machine main body is started, the wire 2 is pulled, and the dancer roller 4 is lifted upward in an arc shape having the bar 5 as a radius around the fulcrum shaft 6. At the same time, the fulcrum rotation shaft 6 also starts to rotate, and the rotation is performed by the gear 8 to rotate the shaft 9 of the first rotary variable resistor 10.
When the gear 11 fixed to is rotated to change the resistance value of the first rotary variable resistor 10 and exceeds the inoperable range of the speed control device shown in FIG. 3, the motor 19 starts normal rotation. Start feeding wires.

The rotation of the motor 19 is transmitted to the bobbin rotation shaft 21 via the belt 20, and the wire supply bobbin 1 mounted thereon rotates to send out the wire 2. The dancer roller swings up to a position where the wire feeding speed due to the rotation of the wire supply bobbin 1 and the machining speed required by the electric discharge machine main body coincide with each other. The wire is stopped at a position where the feeding speed is appropriate, and the wire is continuously fed under a constant tension.

When the machining speed of the electric discharge machine changes, the dancer roller moves up and down to change the resistance value of the first rotary variable resistor, which changes the rotation speed of the motor 19 to supply the wire. The speed is changed, and the wire feed speed is controlled so as to maintain a constant tension.

When the discharge of the wire 2 becomes unnecessary because the electric discharge machine stops machining or the like, the dancer roller 4 swings downward so as to balance the slack of the fed wire, and the motor 19 rotates. Decrease the number.
Further, when the dancer roller 4 moves downward and the resistance value of the first rotary variable resistor reaches the inoperable range of the speed control device shown in FIG. 3, the supply of the current to the motor 19 is stopped. However, since the motor 19 tends to keep rotating due to inertia, it is stopped. Therefore, the stop signal from the stop signal limit switch is transmitted through the cam 7 with an appropriate resistance value (rotation angle position) within a range in which the control device does not operate. The motor 19 is set so as to be braked by a signal.

When the wire is returned from the electric discharge machine due to the cutting of the wire 2 or the like, the dancer roller 4 is further lowered from the stop position, and an appropriate resistance value (rotation angle position) within a range where the control device does not operate. ), The fulcrum rotary shaft 6
Since the limit switch for reverse rotation signal is set to operate via the cam 71 fixed to the motor 19, the motor 19 is electrically rotated reversely by the signal from the limit switch.

On the other hand, a second rotary variable resistor 17 for detecting an angle depending on the remaining amount of the wire is connected to a fulcrum rotary shaft 14 via a bar 13 contacting the wire winding surface of the wire supply bobbin 1 with a roller 12. And the gear 15 and the gear 18, and the resistance value of the second rotary variable resistor corresponds to the remaining wire amount.

The rotation speed of the motor 19 during the reverse rotation is
The control circuit is set so as to be controlled by the resistance value of the rotary variable resistor 17. At the time of reverse rotation, it is electrically separated from the resistance value of the first rotary variable resistor. Further, another variable resistor having a small capacity can be provided for fine adjustment in series with the second rotary variable resistor.

The remaining wire amount detecting mechanism shown in FIG.
Is in contact with the surface of the wound wire of the wire supply bobbin 1 by its own weight via the roller 12, and when the amount of wire winding decreases, the resistance value of the second rotary variable resistor according to the inclination angle θ of the bar 13 And the length of rewinding during reverse rotation per unit time can be kept constant.

In this embodiment, a reversible induction motor 4 of Oriental Motor Co., Ltd. is used as the motor.
1K25RGN-A was used, and the company's speed control pack SS-30 was used as the speed control device.
A variable resistor FG281 of Tokyo Cosmos Co., Ltd. was used as a first rotary variable resistor corresponding to the variable resistor for speed setting. Since the range of the non-operational resistance value of this speed control pack was 0 to 2 KΩ, the first variable resistor was selected to have a maximum resistance value of 20 KΩ, and the resistance value at the reference position of the dancer roller was 2 KΩ. The relative angle of the first rotary variable resistor is set so that the resistance value is 1.9 KΩ as the motor stop signal position and 0.6 KΩ as the motor reverse rotation signal position. Set the operating position of the limit switch. Further, as the second rotary variable resistor for detecting the remaining wire amount, RV24YN of Tokyo Cosmos Co., Ltd. having a maximum resistance value of 20 KΩ was used.

[0025]

According to the present invention, a relatively inexpensive ordinary rotary variable resistor is used to control a wire feeding device of a wire electric discharge machine, and a forward rotation of a wire feeding bobbin driving motor is performed. Feeding), stop (inertial rotation stop brake)
Switching between reverse and reverse rotation (rewind) and accurately controlling the wire feed speed during normal rotation to the speed required by the electric discharge machine, and controlling the wire rewind speed during reverse rotation to a speed that takes into account the amount of remaining wire Therefore, an inexpensive and high-performance wire supply device can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a wire supply device according to an example of the present invention.

FIG. 2 is a configuration diagram of a remaining wire amount detection unit using a second rotary variable resistor according to the present invention.

FIG. 3 is a schematic diagram showing a non-operation range of a speed control device based on a resistance value.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wire supply bobbin 2 Wire 3 Guide roller 4 Dancer roller 5, 13 Bar 6, 14 Rotary shaft for fulcrum 7 Stop signal cam 71 Cam for reverse rotation signal 8, 11 Gear 15, 18 Gear 10, 17 Rotary variable resistor 12 Roller 19 Drive motor 20 Belt 21 Wire supply bobbin rotating shaft

Claims (2)

[Claims] In a wire feeder for a wire electric discharge machine, comprising a dancer roller, a wire supply bobbin and an auxiliary reel, a displacement angle of a dancer roller from a reference position is detected by a first rotary variable resistor. When controlling the rotation of the wire supply bobbin in the sending direction, the stop signal and the rewind signal to the speed control device of the motor, which are the power, are controlled by the rotation type variable corresponding to the range of the inoperable resistance value of the speed control device. A wire feeder, wherein a cam and a limit switch are installed at a swing angle portion directly connected to a resistor to control the motor. 2. The method according to claim 1, wherein when the wire is unwound, the remaining amount of the wire in the wire supply bobbin is detected using a second rotary variable resistor, and the rotational speed of the motor, which is power, is determined according to the remaining amount of the wire. A wire supply device characterized in that it is controlled by a wire feeder.