JPS63126673A - Power source for arc welding - Google Patents

Abstract

PURPOSE:To prevent the occurrence of an agglomerate of the wire tip by continuing to supply the same welding output as just before the welding is stopped in the first time limit close to the feed speed at the time of the normal welding and making the welding output in a pulse shape including an unwelding period in the second time limit where the feed is slowed down. CONSTITUTION:Then a starting signal Ts is turned off and a command of the welding finishing is inputted, a first timer circuit 12 starts to count the first time limit and outputs a first timer signal Tt1. An output control circuit part 14 outputs a motor control signal Vm to stop a motor 10 for feeding a welding wire. Since the rotational speed of the motor 10 is not slowed down by inertia in said first time limit, the same output instruction signal Vq as at the time of welding is sent to a welding output controlling element 4. When the circuit 12 finishes to count the first time limit, a second timer circuit part 13 starts to count the second time limit by the first timer signal Tt1 and outputs a second timer signal Tt2. Then, the control signal Vm to stop the motor 10 is outputted and the output instruction signal Vq to include the unwelding period is outputted to the welding output controlling element 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is an arc welding power source that automatically feeds a welding wire, which is a consumable electrode, and is used to shape the tip of the wire at the end of welding. This relates to a welding power source.

Conventional Techniques Conventional techniques for sharpening the shape of the wire tip at the end of welding and smoothing the arc startability at the start of the next weld include the power reduction method and the power pulse method.

The output reduction method stops the welding wire feed motor when a command to stop welding is input, and outputs a welding output corresponding to a wire feed speed smaller than the output immediately before stopping welding for a certain period of time to feed the wire. The short output pulse method waits for the feed motor to completely stop and reduces the amount of molten lump at the tip of the wire that occurs during that time. At the same time as the welding stops, the welding output is pulsed including a non-energizing period, and if the wire comes into contact with the workpiece due to the inertia of the motor, the pulse output melts the wire tip and prevents arc generation and maintenance during the non-energizing period. This prevents the formation of balls at the tip of the wire.

The problem that the invention aims to solve The problems with the conventional technology are as follows.

First, in the power reduction method, since the arc is maintained, the molten mass at the tip of the wire continues to grow due to the arc heat, and the growth rate is only suppressed, but not completely. In addition, even if the output is reduced, if it continues for a long time, the result will be the same as when the output is not reduced, so unless the output reduction time is strictly controlled, it will not be possible to suppress the balls, and conversely, welding in a wire stick state Sometimes it ends. For this reason, welding machines that use conventional output reduction methods are equipped with an output reduction regulator,
However, if the wire stick phenomenon could not be prevented, it was necessary to incorporate a built-in switch to enable or disable output reduction control.

In the output pulse method, as a result of forcibly providing a non-current period, it is possible to prevent arc maintenance and the formation of a ball at the tip of the wire, but on the other hand, a short-circuit transition is forced from the time when the wire feeding motor starts to decelerate. Therefore, the impact of wire contact is large, and even though spatter performance is low during welding, especially in pulsed arc welding, a large amount of spatter is generated at the end of welding, impairing welding performance.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a time starting point when a start signal for controlling the start and stop of welding is input, and when the start signal changes from welding to stop welding. a first timer circuit unit that starts a first time period by counting the clocks and outputs a first timer signal by changing the state between the clocks of the first time period and other times;
The first timer signal is input and the second time period is started from the time when the counting of the first time period is completed, and the state is changed between the counting of the second time period and other periods. a second timer circuit unit that outputs two timer signals, a welding wire feeding motor that receives the start signal, the first timer signal, and the second timer signal as input, and when the welding is stopped and the first time period is being counted; It outputs a motor control signal to stop the welding, and outputs an output command signal to the welding output control element to command the same output as immediately before the welding stop, and stops the welding wire feed motor while counting the second time period at the welding stop. The output control circuit unit outputs a motor control signal to stop the motor and outputs an output command signal including a plurality of non-energizing periods to a welding output control element.

Although a command to stop welding is input by the means and a stop signal is sent to the wire feeding motor, the wire feeding amount is not sufficiently decelerated and the first time period is close to the feeding speed during steady welding. Inside, the same welding output as immediately before welding is stopped is continued, suppressing the impact caused by wire contact and preventing large amounts of spatter. In the second time period when the wire feeding is sufficiently decelerated, the welding output is pulsed including a non-energizing period, and even if the wire contacts and releases the contact, the arc is maintained at a distance and the formation of a ball at the tip of the wire is prevented. do.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 and 2. In Fig. 1, 1 is the input terminal of the arc welding power source, 2 is the main transformer section, 3 is the rectifier/smoothing section, 4 is the welding output control element, 5 is the reactor, 6 is the regenerative diode, and 7 is the Output terminal of arc welding power supply, 8 is contact tip for energization,
9 is a welding wire, 1o is a welding wire feeding motor, 1
1 is a workpiece to be welded, 12 is a first timer circuit section, 13 is a second timer circuit section, and 14 is an output control circuit section. Figure 2 shows the activation signal T3 for each signal and each output written in Figure 1.
FIG. 3 is a signal waveform diagram when the welding is turned off (when welding is stopped).

When the start signal is turned OFF and a command to finish welding is input, the first timer circuit section 12 starts counting the first time period. 1
Outputs timer signal Tt1. The output control circuit section 14 is T
The fact that the s-times signal has turned OFF and the first timer signal Tt1
detects that it is counting the first time period, and outputs a motor control signal v to stop the welding wire feeding motor 1°.
Output M.

However, within the first time period of -, the rotation speed F of the welding wire feed motor 10 is hardly decelerated due to its inertia, so the welding output control element 4 (with respect to it) receives the same output command signal Vo as during welding. The above is the operation of the output control circuit unit 14 in the first time period.

When the first timer circuit section 12 completes counting the first time period, the second timer circuit section 13 starts the second time period according to the first timer signal Tt1.
The output control circuit unit 14 starts counting the second time period and outputs the second timer signal "t2, which is in the process of counting the second time period.
It detects that the double signal is OFF and that the second timer signal Tt2 is counting the second time period, and outputs a motor control signal vM that commands the welding wire feeding motor 10 to stop, and also controls the welding output. For the element 4, an output command signal V that periodically includes a non-current period (T in FIG. 2) is provided.
Output Q. That is, in the second time period, the welding wire feed motor 10 is almost stopped, so there is little possibility that the welding wire 9 will come into contact with the workpiece 11.
Furthermore, even if they make contact, the contact force is small. Therefore, the non-current period serves to prevent the formation of a ball at the tip of the welding wire due to arc maintenance, and when contact occurs, the contact portion is melted to prevent the stick phenomenon. The above is the explanation of FIGS. 1 and 2.

Note that in carrying out the present invention, the first timer circuit section 12
．． Second timer circuit section 13. The output control circuit section 14 can be realized all together using a microcomputer. Third
The figure is a flowchart of the program in this case.

In Fig. 3, the start signal Ts is turned OFF without welding.
The explanation will start from the standby state (Po). In this standby state, both the motor control signal vM and the output command signal VQ are instructed to turn off until the start signal turns on (P
Repeat execution of the same route in o). When the start signal turns ON, it moves in the (Pl) direction and the welding wire feed motor 1o
is turned ON to output a signal multiplied by vM so as to achieve a predetermined welding rate, and a signal multiplied by Vo to obtain a predetermined welding output. In this state, the start signal is turned OFF, that is, the path (Pl) is repeated until a command to stop welding is input. When a command to stop welding is input, the program proceeds in the direction of (P2), resets and clears the value of the first timer to 0, and starts counting for the first time period. During this time.

The wire feed motor 10 is instructed to stop, but the welding output control element 4 continues to output the conditions immediately before the command to stop welding was input, and during the period when the wire feed motor is hardly decelerated. The same conditions as during steady welding are continued to be output, and the loop of (P3) is repeated until the first time period has elapsed. This time limit can be calculated from the time it takes to run the program, or it can be used as a timer by inputting a clock with a constant cycle into the microcomputer and counting this clock in another program.

When the first time period has elapsed, the program proceeds in the direction (P4), resets and clears the value of the second timer to 0, and starts counting for the second time period. At this stage, the wire feeding motor is sufficiently decelerated.Even if the boil welding arc is actively cut, even if the wire tip contacts the workpiece 11, a large impact force is generated and there is little chance of spatter being scattered. . More importantly, at this stage, it is important to actively extinguish the welding arc to prevent a ball from forming at the tip of the wire in order to ensure a smooth arc start for the next weld. Therefore, in the loop of counting the second time period (P6), while sending a stop command to the wire feeding motor 10, the microcomputer sends a command for an output having a non-energizing period to actively extinguish the arc to the welding output control element. Output to 4. And wire feeding motor 1
After completing the second time period counting, where 0 has completely stopped and there is no danger of wire stick, the program returns to (Po) and returns to the standby state. The above is the program shown in FIG. 3 when the present invention is realized using a microcomputer.
This is an explanation of the flowchart.

Effects of the Invention As is clear from the above explanation, according to the present invention, it is possible to prevent the formation of a ball from growing at the tip of the wire at the end of welding without generating spatter accompanied by a large impact. The stick phenomenon can also be prevented, and the wire tip can have a sharp shape at the end of welding.As a result, the arc startability during the next welding can be made good and uniform, contributing to the industry. Things are big.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram of an arc welding power source showing an embodiment of the present invention, Fig. 2 is a signal waveform diagram of the main part of the same circuit at the end of welding, and Fig. 3 is a block circuit diagram of an arc welding power source showing an embodiment of the present invention. This is a program flowchart when the program is realized. 12...First timer circuit section, 13...
Second timer circuit section, 14...output control circuit section. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 1 Figure 3

Claims (1)

[Claims] A start signal that controls the start and stop of welding is input, and a first time period starts from the time when the start signal changes from welding to stop welding, and during the first time period. and the other, and output the first timer signal by changing the state.
a timer circuit section, and a first timer circuit section receiving the first timer signal as input;
a second timer circuit that starts counting a second time period using the time when the counting of the time period is completed as a time starting point, and outputs a second timer signal by changing the state between counting of the second time period and other times; and inputs the start signal, the first timer signal, and the second timer signal, and outputs a motor control signal to stop the welding wire feed motor while counting the first time period when welding is stopped. Outputs an output command signal to the welding output control element to command the same output as immediately before welding stops, and when welding stops, the second
An output control circuit section that outputs a motor control signal that stops the welding wire feed motor while counting the time limit, and outputs an output command signal that includes multiple non-energizing periods to a welding output control element. power supply.