JPS6215464B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a wire feeding control device.

2. Description of the Related Art Conventionally, it has been known to provide wire feeding devices each equipped with a motor at the sending end and receiving end of the wire to feed the wire in a push-pull manner.

As this type of wire feeding control device, for example, as shown in FIG. speed control,
The motor 3 for driving the other pull wire feeding device B (referred to as the second feeding device) is connected to a constant voltage power supply circuit 4.
The welding wire 7 is synchronously controlled via the resistor 5 to be synchronized with the wire feeding operation of the first feeding device A, and the welding wire 7 is passed through the conduit 8 while being unwound from the take-up reel 6. There is one that is designed to feed the welding torch 9.

If the second feeding device B tries to feed the welding wire 7 faster than the first feeding device A and the motor 3 becomes overloaded, the electric motor of the motor 3 of the feeding device B The driving speed of the motor 3 is reduced due to the voltage drop between the motor 3 and the resistor 5 connected in series with the motor 3, thereby reducing the wire feeding speed by the feeding device B. The feeding speed is made to match the feeding speed by feeding device A.

In order to feed the welding wire 7 at a predetermined speed and in a stable state, the second feeding device B needs to be sufficiently synchronized with the first feeding device A. However, the load on the second feeding device B is subject to considerable fluctuations, such as the frictional resistance force acting on the welding wire 7 within the conduit 8 and the frictional resistance force acting on the welding wire 7 when passing through the current-carrying tip of the welding torch 9. Includes things that are easy to do. Therefore, there is a very high risk that the wire feeding speed of the second feeding device B will be significantly different from the wire feeding speed of the first feeding device A, that is, the so-called "out of synchronization". The conventional wire feeding control device has a serious drawback of lacking stability in wire feeding.

The present invention has been made to eliminate the above-mentioned drawbacks, and the present invention has been made in order to eliminate the above-mentioned drawbacks. An upper limit value and a lower limit value determined by the wire diameter and motor capacity are set as appropriate, and the current supplied to the motor of the second feeding device is set to a value within the range of the lower limit value to the upper limit value. While controlling the output of the constant voltage power supply circuit that supplies power to the motor of the second feeding device,
When the current supplied to the motor of the second feeding device is within the above range, the motor of the second feeding device is supplied with a constant voltage commensurate with the wire feeding speed by the first feeding device. so that the second
Even if the load on the second feeding device fluctuates greatly, the second
quickly matching the wire feeding rate by the first feeding device to the wire feeding rate by the first feeding device,
It is an object of the present invention to provide a wire feeding control method and device that can perform stable wire feeding by preventing the occurrence of "out of synchronization" due to fluctuations in the load of a second feeding device.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 2, parts equivalent to the components of the apparatus shown in FIG. 1 are designated by the same reference numerals and their explanations will be omitted.

In FIG. 2, 11-1 and 11-2 are Darlington-connected power transistors for constant voltage control of the voltage applied to the motor 3 of the feeder B on the synchronous control side. both transistors 11
The collectors of -1 and 11-2 are commonly connected to the positive terminal of a DC power supply 12 of a predetermined voltage, and the emitter of one transistor 11-1 is connected to the motor 3.
It is connected to the negative terminal of the DC power supply 12 via a resistor 14 with a low resistance value for detecting the current flowing to the armature. And the other transistor 11
-2 base is connected to both transistors 11-1 and 11
-2, i.e., transistor 11-1
It is connected to the negative terminal of the current power source 12 via a capacitor 13 for setting a reference value for the emitter voltage.

Reference numeral 17 denotes a potentiometer for setting the lower limit value of the current flowing through the motor 3, and 18 indicates a signal representing the lower limit current value Imin of the output of the potentiometer 17 and a value of the armature current flowing through the motor 3 using the resistor 14. An operational amplifier 19 that differentially receives a signal representing Ix is a transistor for controlling charging of the capacitor 13 whose base is connected to the operational amplifier 18. The collector of this transistor 19 is connected to the positive terminal of the DC power supply 12, and the emitter is connected to the transistor 11 through a charging resistor 20.
-2 is connected to the connection point 15 between the base of the capacitor 13 and the capacitor 13.

When the detected current value Ix is smaller than the lower limit current value Imin, the output voltage of the operational amplifier 18 becomes a positive high level proportional to the difference value (Imin-Ix), the transistor 19 is turned on, and the capacitor 13 is The transistor 1 is powered by the DC power supply 12.
9, charged through the resistor 20, its charging voltage increases, this voltage is applied to the base of the transistor 11-2, and therefore the transistor 11-
1 is increased, the current supplied from the DC power supply 12 to the motor 3 via the transistor 11-1 increases, and the output of the motor 3 increases in accordance with the increase in the charging voltage of the capacitor 13. It is starting to increase.

On the other hand, when the detected current value Ix becomes larger than the lower limit current value Imin and smaller than the upper limit current value Imax, the output voltage of the operational amplifier 18 becomes negative, and the transistor 19 is turned off. Therefore, the base potential of the transistor 11-2 is the same as that of the capacitor 1.
Therefore, the emitter voltage of transistor 11-1 is
The voltage is constant depending on the charging voltage of the capacitor 13. This voltage is applied to the armature of the motor 3, and the motor 3 is controlled at a constant speed. The time constant of the discharge circuit formed by the capacitor 13 and the resistor 27 is set to a sufficiently large value.

In this way, the potentiometer 17, the operational amplifier 18, the transistor 19, and the resistor 20 constitute a set voltage increasing circuit 21 for boosting the voltage applied to the motor 3 from the DC power supply 12.
Next, 22 is a potentiometer that sets the upper limit value of the current flowing through the motor 3, and 23 is a signal representing the upper limit current value Imax of the output of the potentiometer 22, and the armature of the motor 3 that is connected to the resistor 14. An operational amplifier 24 that differentially receives a signal representing the current value Ix is a transistor for controlling the discharging of the capacitor 13 whose base is connected to the operational amplifier 23. It is connected to the connection point 15 through a resistor 25, and its collector is connected to the negative terminal of the DC power supply 12.

When the detected current value Ix is larger than the upper limit current value Imax, the output voltage of the operational amplifier 23 is negative, and therefore the base potential of the transistor 24 is negative, the transistor 24 is turned on, and the capacitor 13 The charged charge is discharged through the resistor 25 and the transistor 24, and
The charged voltage is reduced and this voltage is applied to the base of transistor 11-2, thus
The base potential of the transistor 11-1 is reduced,
The current supplied from the DC power supply 12 to the motor 3 via the transistor 11-1 is reduced, and the output of the motor 3 is reduced in accordance with the reduction in the charging voltage of the capacitor 13.

On the other hand, when the detected current value Ix is smaller than the lower limit current value Imin, the output voltage of the operational amplifier 23 becomes a positive high level, the base potential of the transistor 24 is also set to a high level, and the transistor 24 is turned off. be done. Therefore, in the same way as in the set voltage increase circuit 21 described above, the emitter voltage of the transistor 11-1 is controlled to a constant voltage according to the voltage of the capacitor 13, and the motor 3 is It is designed to be driven at a constant speed commensurate with the feeding speed.

In this way, the potentiometer 22, the operational amplifier 23, the transistor 24, and the resistor 25 constitute a set voltage drop circuit 26 for reducing the voltage applied to the motor 3 from the DC power supply 12.

The motor 1 of the other feeder A, which is controlled at a constant speed, is controlled at a constant speed by a constant voltage control circuit 2, as shown in FIG.

Next, the operation of the wire feeding control device configured as described above will be explained.

The potentiometer 17 in the set voltage increase circuit 21 is set to a lower limit current value Imin, for example 1.5A, and the potentiometer 22 in the set voltage drop circuit 26 is set to an upper limit current value Imax, for example 1.8A. Suppose that

The motor 1 of the feeding device A is operated at a constant speed by a constant voltage control circuit 2 in a known manner, while
The motor 3 of the feeding device B is driven by the circuit shown in FIG. 2, and welding is performed while the welding wire 7 is fed to the welding torch 9 through the conduit 8 at a predetermined speed, similar to the known push-pull method. It is assumed that

Now, if the feeding speed of feeding device B becomes slower than that of feeding device A for some reason, the welding wire 7 becomes slack in the conduit 8 and the feeding speed of feeding device B becomes slower.
It is assumed that the load on the motor 3 decreases and the armature current Ix of the motor 3 detected by the resistor 14 becomes smaller than the lower limit current value 1.5A.

The operational amplifier 18 determines that the detected current value Ix of the voltage signal from the terminal 14-1 of the resistor 14 is smaller than the lower limit current value 1.5 A from the potentiometer 17, and applies a difference value ( Ix−
Apply a positive high level signal according to 1.5).
Therefore, the transistor 19 is turned on, and the DC power supply 12 turns on the transistor 19 and the resistor 20.
, the capacitor 13 is charged and its positive potential is increased, so that the transistor 11
The base potential of transistor 11-2 also rises, and
2 emitter, base of transistor 11-1,
The potential of the emitter also rises at the same time, the voltage supplied to the motor 3 increases, and the feeding speed of the welding wire 7 by the feeding device B increases. The rising speed is determined by the product of the capacitance of the capacitor 13 and the resistance value of the resistor 20, that is, a time constant, and the value is experimentally determined to be approximately 0.1 to 1 second.

When the detected current value Ix increases to reach 1.5A and the wire feeding speed by feeding device B becomes almost equal to the wire feeding speed by feeding device A, the output of the operational amplifier 18 becomes almost zero. The base potential of the transistor 19 becomes low level, the transistor 19 is turned off, and charging of the capacitor 13 is stopped. As a result, the base potential of the transistor 11-2 is made to correspond to the charging voltage of the capacitor 13, and therefore the emitter voltage of the transistor 11-1, that is, the voltage applied to the motor 3, is the voltage applied to the capacitor 13.
The voltage of the motor 3 and, therefore, the feeder B
is controlled at a constant speed so that the welding wire 7 is fed at approximately the same speed as the wire feeding speed by the feeding device A corresponding to the charging voltage of the capacitor 13.

Next, if feeder B accidentally begins to feed the welding wire 7 faster than feeder A, the welding wire stretches within the conduit 8 and the current value of feeder B increases.

The operational amplifier 23 detects the current value detected from the resistor 14.
Ix is the upper limit value 1.8A from potentiometer 22
A low level signal of approximately zero is applied to the base of the transistor 24. Therefore, the transistor 24 is turned on, and the electric charge of the capacitor 13 is discharged through the resistor 25 and the transistor 24, the charging voltage of the capacitor 13 is lowered, and the base potential of the transistor 11-2 is lowered.

Therefore, contrary to the case described above, the emitter potential of the transistor 11-1 decreases, the voltage supplied to the motor 3 decreases, and the feeding speed of the welding wire 7 by the feeding device B decreases.

The above detected current value Ix has decreased and the upper limit current value is 1.8A.
When the output of the operational amplifier 23 reaches a positive high level, the base potential of the transistor 24 also becomes a high level, the transistor 24 is turned off, and the discharge of the capacitor 13 is stopped.

Thereafter, in the same manner as described above, the emitter voltage of the transistor 11-1, that is, the voltage applied to the motor 3, is controlled at a constant voltage to be a constant value according to the charging voltage of the capacitor 13, and the voltage applied to the motor 3 is controlled to be constant. Therefore, the feeding device B is controlled at a constant speed so that the welding wire 7 is fed at substantially the same speed as the wire feeding speed by the feeding device A.

In this way, even if the load applied to the motor 3 of the feeding device B fluctuates greatly, the set voltage increase circuit 21 and the set voltage drop circuit 2
6, the current supplied to the motor 3 is automatically adjusted and the motor 3 is driven at a constant speed.
When the load on the motor 3 fluctuates within a range corresponding to the range from the lower limit current value Imin to the upper limit current value Imax, the motor 3 is configured with transistors 11-1 and 11-2 and a capacitor 13. It is driven at a constant speed by a constant voltage control circuit. Therefore, no matter how the load on the motor 3 changes, the motor 3 is stably driven at a constant speed commensurate with the wire feeding speed of the wire feeding device A. B is less susceptible to load fluctuations and is driven more stably in synchronization with the feeder A, making it possible to feed the welding wire 7 very stably.

In addition, as shown in FIG. 3, the above-mentioned feed control device connects the positive terminal 1-1 of the motor 1 of the feed device A, which receives a predetermined DC voltage from the constant voltage control circuit 2 and is controlled at a constant speed, to The connection point 15 is connected to the connection point 15 through a time-limited normally open contact 30 such as a relay that responds to a start command switch (not shown) of the feed control device, and the negative terminal 1-2 of the motor 1 is connected to the connection point 15. It may be configured by connecting to the negative terminal of the DC power supply 12 of the feeding device B.

In this way, when the start command switch of the feed control device is turned on and the feed devices A and B are started, the output voltage from the constant voltage control circuit 2 applied to the motor 1 is controlled as described above. is applied to the capacitor 13 through the contact 30, and the capacitor 13
By adjusting the charging voltage to match the voltage applied to the motor 1, the driving speed of the motor 3 of the feeding device B can be made to match the driving speed of the motor 1 more quickly than the device shown in FIG. be able to. That is, the wire feeding speed by the feeding device B can be quickly made to match the wire feeding speed by the feeding device A.

In this case, if the voltage-driving speed characteristic curves of motor 1 of both feeders A and motor 3 of B do not match each other, a transformer (not shown) with a constant ratio corresponding to the voltage ratio is used. The voltage applied to the armature of the motor 1 immediately after startup may be applied to the capacitor 13 via the upper starting contact 30. In this way, as described above, the wire feeding speed by the feeding device B can be made to match, that is, synchronized, with the wire feeding speed by the feeding device A quickly after startup.

Further, in the above embodiment, the welding wire 7
We have explained the case of sending , but for example,
Of course, the above-described feeding control device can also be applied to feeding other wires such as wire ropes.

As described in detail above, according to the present invention, when feeding a wire using the push-pull method, the second feeding device is controlled to be synchronized with the motor of the first feeding device, which is controlled at a constant speed. An upper limit value and a lower limit value are appropriately set for the power supply current to the motor of the second feeding device, and when the power supply current to the motor of the second feeding device is below the lower limit value, the power supply voltage is increased, When the power supply voltage is greater than or equal to the upper limit value, the power supply voltage is reduced, and when the power supply voltage is within the range of the lower limit value to the upper limit value, the wire is sent to the motor of the second feeder by the first feeder. Since the power is supplied at a constant voltage commensurate with the supply speed,
Even if the force acting on the wire to be fed using a conduit, especially a long conduit, fluctuates greatly, the wire feeding speed by the second feeding device can be quickly reduced by the wire feeding speed by the first feeding device. Can be matched to wire feeding speed. Therefore, the wire can be fed very stably at a predetermined speed without synchronization of the second feeding device with respect to the first feeding device.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the basic configuration of an example of a conventional push-pull type wire feeding control device, and FIG. 2 shows the main components of a wire feeding control device according to an embodiment of the present invention. Electrical circuit diagram, 3rd
The figure is an electrical circuit diagram of the main components of another embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Constant speed control side motor, 2... Constant voltage control circuit, 3... Synchronous control side motor, 6... Reel, 7... Welding wire, 8... Conduit, 9...
...Welding torch, 11-1, 11-2...Power transistor, 12...DC constant voltage power supply, 13...
... Capacitor for setting the reference voltage, 14 ... Resistor for detecting the current supplied to the motor, 17 ... Potentiometer for setting the lower limit current value, 18 ... Operational amplifier, 19 ... Transistor, 20 ... For charging Resistor 21... Set voltage increase circuit, 22... Potentiometer for setting upper limit current value, 23... Operational amplifier, 24... Transistor, 25... Resistor for discharging, 26... Set voltage drop circuit , 27...Resistor, 30...Normally open contact of time-limited return switch, A
...Wire feeding device on the constant speed control side (first feeding device), B...Wire feeding device on the synchronous control side (second feeding device)
feeding device).

Claims (1)

[Claims] 1. A first wire feeding device including a motor controlled at a constant speed, and a second wire including a motor controlled in synchronization with the motor of the first wire feeding device. A wire feeding control device that feeds a wire in a push-pull manner by a feeding device, comprising: a constant voltage power source that supplies power to the second wire feeding device; and a second wire feeding device from the constant voltage power source. a detection circuit that detects the current supplied to the motor of the second wire feeding device; and a detection circuit that is connected between the constant voltage power supply and the motor of the second wire feeding device, and a detected current value of the output of the detection circuit is arbitrarily set. When the voltage exceeds the upper limit set, the voltage supplied to the motor from the constant voltage power supply is reduced, and when the voltage becomes smaller than the arbitrarily set lower limit, the voltage supplied from the constant voltage power supply to the motor is increased. Or, when the magnitude is within the range from the lower limit value to the upper limit value, a power supply is configured to supply power from the constant voltage power supply to the motor with a constant voltage commensurate with the wire feeding speed by the first wire feeding device. A wire feeding control device comprising a control circuit.