JPH0342180A - Arc welding controller - Google Patents

Abstract

PURPOSE:To reduce a cycle time by providing an inversion circuit part to invert the rotating direction of a wire feed motor in a moment by a signal of welding completion and providing a driving circuit part of the above-mentioned wire feed motor close to this wire feed motor. CONSTITUTION:Since the rotating direction of the wire feed motor 4 is inverted in a moment when welding is completed, wire running by inertia can be prevented. Consequently, the need for deposition detection processing by a robot is eliminated and the cycle time of a robot system can be reduced. In addition, the driving circuit part of the wire feed motor 4 is set up close to this wire feed motor 4. By this method, a cable length connected to a motor armature circuit can be reduced and a reverse direction value is increased and dynamic braking torque is increased, so wire running by inertia is further prevented. By this method, deposition on a work caused by wire running with inertia is prevented and the occurrence of damage and deformation of the controller can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an arc welding control device for performing arc welding using a welding wire, and particularly to a control device for forwarding and reversing a feed motor using a welding wire. do.

[Conventional technology]

A general automatic consumable power FX type single welding machine currently in use is constructed as shown in FIG.

A welding torch 3 is attached to the robot manipulator 1 via a robot arm 2.
is provided with a wire feed motor 4. This wire feed motor 4 is driven by being directly supplied with voltage from a welding machine 6 placed on a pedestal 5 via a cable 7. Then, the wire feeding motor takes out the welding wire 8 from a wire bag (not shown), passes through the conduit tube 9, and feeds it to the welding torch 3.

Further, a voltage is applied from the welding machine 6 between the wire 8 and the workpiece 11 on the workpiece mounting table 10 via a dynamic cable (not shown), and a welding current is supplied to perform arc welding. Furthermore, a control device 12 is provided on the pedestal 5, and controls the operation of the robot manipulator 1, and also controls the welding start and end signals, welding v test E, and current 1 si J to the welding fusion 6 via a control cable 13. Command signals etc. are output.

FIG. 5 shows a circuit configuration of a conventional welding machine 6 and a control device 12. In the circuit of this welding machine 6, only the heel motion circuit of the wire feed motor 4 is extracted and shown.

The control device 12 sends a contact signal 1 instructing the start and end of welding.
21 and welding' are condition command voltage signals 122 for setting the flow.
is output.

In the welding machine 6, an interface relay (CRI) 14 receives the welding start/end signal from the control device 12, and as this (CRI) 14 turns ON and OFF,
The specific voltage for application of the armature voltage of the wire feed motor 4 produced by the rectifier unit 15 is controlled by the speed control units 16 and 5C.
Chopper control is performed by R17, and rotation, stopping, and speed control are performed by applying this voltage to the motor 4.

In the conventional automatic consuming HYV type arc welding machine configured as described above, it takes some time for the wire feed motor 4 to completely stop rotating after the welding end signal is issued. Therefore, even if the welding machine 6 receives the welding end signal, some wire coasting still remains, and the welding wire 8
may be welded to the workpiece 11, or the welding wire 8 may protrude for a long time from a tip (not shown) provided on the torch 3.

If the torch 3 is moved by the robot with the welding wire 8 welded to the workpiece 11, there is a risk that some kind of mechanical damage or deformation will occur to the torch 3 or the robot's wrist. In addition, if the wire protrusion length becomes longer than a predetermined length, the welding wire 8 will come into contact with the workpiece before welding starts when the torch 3 is moved to the next welding start point by the robot, and if it is excessive, the torch 3 will be pushed up. Put it away.

Furthermore, there is a risk that the welding wire 8 that protrudes excessively at the start of welding may fly off and remain in the welding bead, resulting in damage to the hands and fingers of the worker holding the product.

To solve this problem, Japanese Patent Application Laid-Open No. 60-221175
As described in the publication, even after receiving the welding end signal at the end of 78 welding, the welding voltage is applied between the torch and the workpiece for a predetermined period of time to maintain the arc for the entire arc, and the welding wire coasts and the arc A method is known in which melting is performed by sustaining .

This processing method is called anti-stick.

The arc i8 contact robot movement speed, welding signal, wire feed motor rotation speed, which performs this anti-stick processing,
Figure 6 shows the changes in welding voltage and welding current. As shown in the figure, even when the robot stops moving and the welding signal is turned off, the wire feed motor continues to rotate for a certain period of time, and the welding voltage is applied and welding current flows for a certain period of time.

[Problem to be solved by the invention]

However, according to the conventional anti-stick processing described above, after the welding signal is turned OFF, the distance between the torch and the workpiece is maintained at a predetermined distance, and the torch is moved by the robot for a predetermined period of time, as shown in FIG. need to be stopped. If the torch is moved to the next welding start point immediately after the welding end signal is sent, the welding wire will not be melted and will remain stuck out for a long time, and the above-mentioned problem will not be solved. Time to stop the robot movement for stick processing: 0.39
That's about it.

Furthermore, even if the anti-stick treatment described above is performed, it is not always possible to completely prevent the welding wire from sticking to the workpiece.
Although the incidence is low, welding may occur. At this time, if the robot continues to run without making any checks,
Since there is a risk of occurrence of the above-described damage, it is common, especially in robot systems, to perform welding detection processing after issuing a welding end signal.

This detection process is performed by applying a voltage of approximately 12 V DC between the torch and the workpiece, and determining that welding has occurred if the electrical resistance is close to zero. When welding is detected, the next robot Stop sliding onto the step and ask the worker to maintain control. This welding detection process also requires about 0.5 seconds to 0.8 seconds after the welding completion signal is sent.

In other words, in arc welding for robot systems,
The above-mentioned stopping time of 0.5 seconds to 0.8 seconds occurs per welding line. For example, in today's world where production lines are produced using 20 dead parts, it is common for one program to require more than 7 units of engineering time. Therefore, there is a problem in that when producing one-piece workpieces, a loss time of at least 5 seconds or more occurs within the cycle time, reducing production efficiency.

On the other hand, in actual equipment, the production line space is minimized to make effective use of the factory premises, and at the same time, the walking distance of workers is shortened.

For this reason, as shown in FIG. 4, welding machine 6 and control device 1
2 is often placed on a pedestal 5.

As a result, the cable 7 connecting the welding machine 6 and the wire feed motor 4 becomes long, and may be, for example, 10 m to 30 m long. For this reason, the electrical resistance value of the cable 7 is on the order of several ohms, resulting in a problem in that the responsiveness to changes in the speed command to the wire feed motor 4 becomes slow and the speed controllability deteriorates.

In particular, according to the conventional speed control system of a welding machine shown in Fig. 5, a reverse current using the back electromotive force generated by the rotation of the motor 4 as an energy source is transmitted to the resistor R via the back contact of the relay CRI. Since the motor is stopped at the end of welding using the self-braking torque obtained by this, so-called dynamic braking torque, if the cable 7 is long, the electric resistance, and in some cases the actance of the beam, will increase and the reverse current value will decrease. . As a result, the braking torque for braking the wire feed motor 4 is reduced, resulting in a disadvantage that the wire coasting time becomes longer.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an arc welding control device that can prevent the welding wire from adhering to the workpiece at the end of welding, and can shorten the welding cycle time in a robot system. purpose.

[Means to solve the problem]

To achieve the above object, the present invention feeds the welding wire to the welding torch by a wire feeding motor.

The arc welding control device for performing arc welding by applying a voltage between the welding wire and the workpiece includes a reversing circuit unit that instantaneously reverses the rotational direction of the wire feed motor in response to a welding end signal. In addition, the opening circuit section of the wire feeding motor is provided close to the wire feeding motor.

[Effect]

According to the above configuration, the rotational direction of the wire feed motor is instantly reversed when welding is completed, so it is possible to prevent wire coasting, and as a result, there is no need for welding detection processing by the robot, which reduces the cycle time of the robot system. can be shortened. In addition, by installing the drive circuit of the wire feed motor close to the wire feed motor, the length of the cable connected to the motor armature circuit can be shortened, and the electrical resistance value of the cable can be reduced. Since the reverse direction value can be increased and the generated braking torque can be increased, wire coasting can be further prevented.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an arc welding control device according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. The feature of the non-embodiment is that of the speed control unit 16 built in the conventional welding machine 6 shown in FIG. The reversal circuit section of the wire feeding motor 4 is provided close to this motor 4, and a reversing circuit section 102 for instantaneously rotating the motor 4 in reverse at the end of welding is provided within the control unit 103.

The reverse circuit section 102 includes a relay CR2 that serves as an interface for the relay CRI in the welding machine 6 and constitutes a normal rotation circuit.
, a condition relay CR3 that configures a reverse circuit, a precision timer T that sets a predetermined time ΔT from the time of receiving a welding signal, and a relay CR4 that is ON only during this time ΔT and configures a reverse circuit. ing.

Note that the forward/reverse switching may be performed using a solid state system such as a transistor instead of using a relay.

In the control unit 103, a conventional welding machine 6 and a rectifying unit 15 are installed. Then, a control unit 103 having a motor active circuit incorporating the above functions is installed in the immediate vicinity of the wire feed motor 4,
The length of the cable 7 connected to the motor armature circuit is minimized.

On the other hand, in the welding machine 6, in addition to the power supply circuit section 101 and the rotational speed control unit 16, a command switching unit 105 having a setting device 104 for applying a temperature command pressure at the time of reverse rotation is additionally provided. .

Next, the operation of this embodiment will be explained.

Figure 2 shows the fluctuations of the robot moving speed, welding signal, and motor rotation speed over time, and Figure 3 shows each relay CR.
The sequences of I, CR2, CR3, and CR4 are shown. Relay CR4 waits for a predetermined time Δ immediately after receiving the welding end signal.
It is ON only during T.

Furthermore, when it is confirmed that the torch has reached the pre-taught welding end point, a welding end signal is issued and the robot immediately moves to the next step. At this time, the motor 4 is immediately reversed for a predetermined time ΔT. The speed of 7 degrees during this reverse rotation is set by the setting device 104.

According to this embodiment, as soon as the welding end signal is received, the wire feeding motor 4 reverses for a certain period of time, so that it is possible to prevent the wire from coasting, and to prevent the wire 8 from sticking out and welding to the workpiece 11. This can prevent mechanical damage or deformation of robots, etc. Furthermore, since the motor armature circuit is provided close to the wire feed motor 4, the braking torque when the motor is stopped can be increased to suppress wire fraying. Furthermore, since there is no need for a robot to perform 7-volume discharge processing, the cycle time in the COBOSOTO system can be shortened.

〔Effect of the invention〕

As explained above, according to the present invention, the arc welding control device in the robot system is provided with a reversing circuit section, and the opening circuit section of the wire feeding motor is provided close to this motor, so that the workpiece can be moved by wire coasting. It is possible to prevent welding of the parts, prevent damage or deformation of the device, and shorten the cycle time in the robot system.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is an operation sequence diagram, Fig. 3 is a relay sequence diagram, Fig. 4 is a configuration diagram of an automatic arc welding machine, and Fig. 5 is a conventional The circuit diagram of the arc welding control device shown in FIG. 6 is also an operation sequence diagram. 1... Robot, 3... Welding torch. 4... Wire feed motor, 8... Welding wire, 11
... Workpiece (member to be welded), 12... Control device, 102... Reverse circuit section, ↓03... Control unit (wearing circuit section).

Claims (1)

[Claims] (1) In an arc welding control device for feeding a welding wire to a welding torch by a wire feeding motor and performing arc welding by applying a voltage between the welding wire and a workpiece to be welded, a signal indicating the end of welding is used. The arc welding control is characterized in that a reversing circuit unit for instantaneously reversing the rotational direction of the wire feed motor is provided, and a drive circuit unit for the wire feed motor is provided close to the wire feed motor. Device.