JPH0679789B2 - Control device for resistance welding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention provides a rectifying diode, a current controlling transistor or a thyristor, or a welding transformer used in a welding current circuit within a permissible usage rate. The present invention relates to a control device for a resistance welding machine, which is confirmed to be present and starts post-welding to protect the diode, the transistor, the thyristor, or the like.

(Prior Art) Conventionally, for example, in response to a start signal from a robot controller that is generated intermittently, the welding current of the current value and the energization time set by the current setter and the time setter is intermittently supplied to the welding current circuit. When sequentially welding multiple welding points using the control device of the resistance welding machine that is energized, the usage rate of the rectifying diode, the current control transistor, or the thyristor intervening in the welding current circuit may decrease. The interval of the start signal is set so as to be less than the allowable usage rate to prevent destruction of transistors, diodes and the like.

(Problems to be Solved by the Invention) The above-mentioned work of the worker requires skill, and when the usage rate is set to be over, the diode, the transistor, or the thyristor is disadvantageously burned. .

An object of the present invention is to eliminate such a conventional inconvenience.

(Means for Solving Problems) In order to achieve the above object, the present invention is set by a current setting device and a time setting device in response to a start signal from a robot controller or the like which is intermittently generated. In the control device of the resistance welding machine in which the welding current of the current value and the energizing time is intermittently energized in the welding current circuit, in the welding cycle of a plurality of the time setter that outputs each time the start signal is input. Utilization rate calculating means for accumulating the energization time of the welding current at the welding point and calculating the utilization rate from the integrated value and the time of one welding cycle, and one welding of the current setting device output for each input of the start signal A current integration means for integrating a plurality of welding current values in a cycle to calculate an average welding current value at one welding point; a characteristic data storage means for storing an allowable usage rate characteristic for the current value; and the storage means. From the above, the allowable usage rate for the average welding current value calculated by the current integrating means is read out, the allowable usage rate is compared with the usage rate calculated by the usage rate calculating means, and the quality of the usage rate is judged. And means.

(Operation) First, the operator sets the current value and the energization time of each welding current at a plurality of welding points in one welding cycle and the interval of the start signal generated from the robot controller or the like in the current setting device and the time setting device.

Then, the welding current is not supplied to the welding current circuit, and the robot controller or the like is operated to sequentially generate the start signal.

The determination means compares the usage rate calculated by the usage rate calculation means with the allowable usage rate with respect to the set average welding current value in one welding cycle read from the storage means. It is determined whether or not the above. When it is determined that the usage rate is less than the allowable usage rate, the welding current having the current value and the energization time set by the current setter and the time setter is supplied to the welding current circuit. When the usage rate is equal to or higher than the allowable usage rate,
The time interval of the start signal generated from the robot controller etc. is corrected again.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of the present invention.

In the figure, 1 is a current setting device for setting a welding current flowing through a plurality of welding points, 2 is a time setting device for setting a welding current energizing time, and the current setting device 1 and the time setting device 2 are, for example, robot controllers. It is configured to output the digital signals i and t of the current value data and the energization time data which are set for each input of the activation signal a output from, etc., and is connected to the current control circuit 3. The current control circuit 3 is connected between a DC power supply (not shown) and a control pole of a current control element 4 of a transistor or thyristor, and the current control element 4 connected to an AC power supply (not shown) is connected via a welding transformer 5. The current control circuit 3 is connected to the welding tip 6.
Is the welding current detected by the current transformer 7 connected to the secondary side (or primary side) of the welding transformer 5, and is set to the plurality of welding points of one welding cycle set by the current setting device 1. Of each welding current value and each energization time at a plurality of welding points of one welding cycle set by the time setting device 2, and is constituted by the current setting device 1 or the like. The circuit of the control device is not different from the conventional one.

The device of the present invention includes, in addition to the conventional circuits described above, a usage rate calculation circuit 8 as the usage rate calculation means, a current integration circuit 9 as the current integration means, a memory 10 as the characteristic data storage means, and a determination means. The determination circuit 11 is connected and configured, and the switch 12 is interveningly connected to the connection circuit between the current control circuit 3 and the control pole of the current control element 4. The utilization rate calculation circuit 8 integrates the energization time data output from the time setting device 2 and performs one welding from the input pulse, for example, one welding cycle start pulse p from the robot controller and the next welding cycle start pulse p from the robot controller. It is configured to calculate the cycle time and calculate the usage rate in one welding cycle from the time and the integrated value.
Is configured to integrate the current value data output from the current setter 1 and divide the integrated value by the number of welding points in one welding cycle to calculate an average welding current value.
The memory 10 stores the allowable usage rate characteristics of diodes, transistors, etc. with respect to the current value as shown in the second diagram, and the judgment circuit 11 allows the average welding current value calculated by the current integrating circuit 9 to be allowed. The rate is read from the memory 10, the allowable usage rate is compared with the usage rate calculated by the usage rate calculation circuit 8, and when the usage rate is less than or equal to the allowable usage rate, it is judged to be good or defective and this is determined. The display 13 is configured to display.

Next, the operation of this embodiment circuit will be described.

First, the current value of each welding current to be applied to a plurality of welding points in one welding cycle and its energization time are set in the current setter 1 and the time setter 2, and at the same time, the start signal generation time interval generated from the robot controller is set. To do.

Next, before operating the robot controller or the like to pass the welding current to the welding tip, if the robot controller or the like is operated with the switch 12 open, that is, without the welding current flowing to the welding tip, the start signal for each welding point Occurs, and the current setting device 1 and the time setting device 2 are generated by the start signal.
The current value data of the welding current and the energization time data at each welding point are sequentially output as digital signals i, t. The duty ratio calculation circuit 8 uses the start pulse f of one welding cycle.
Then, the usage rate in one welding cycle is calculated from the digital t of the energization time data from the time setting device 2. on the other hand,
The current integration circuit 9 calculates the average welding current value in one welding cycle from the digital signal i of the current value data. Thus, the judgment circuit 11 compares the allowable usage rate with respect to the average welding current value read from the memory 10 with the usage rate calculated by the arithmetic circuit 8, and when the usage rate is less than the allowable usage rate, the indicator 13 Indicates that the usage rate is good, and if the usage rate is equal to or higher than the allowable usage rate, the display unit 13 displays that the usage rate is poor. When the usage rate is good, the operator
Is closed and the operation of the robot controller is started again. If the usage rate is bad, the interval of the start signal of the robot controller is corrected, it is checked again whether the usage rate is below the allowable usage rate, and the operation is repeated until it falls below the allowable usage rate.

In the above embodiments, the usage rate calculation circuit 8 and the current integration circuit 9
Although the judgment circuit 11 is used, these can be replaced with a computer.

(Effect of the invention) As is apparent from the above description, according to the present invention, the operator sets the current value and the energization time of the welding current at each welding point of one welding cycle in the current setter and the time setter. ,
When the time of one welding cycle is set, it is possible to easily check whether the usage rate of the transistor or the like in the one welding cycle is equal to or lower than the allowable usage rate before starting welding.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing an allowable usage rate characteristic with respect to a current value. 1 …… Current setting device 2 …… Time setting device 3 …… Current control circuit 4 …… Current control element 5 …… Welding transformer 8 …… Usage rate calculation circuit 9 …… Current integration circuit 10 …… Memory 11 …… Judgment circuit

Claims (1)

[Claims] 1. A welding current having a current value and a conduction time set by a current setting device and a time setting device is intermittently supplied to a welding current circuit in response to a start signal from a robot controller or the like which is generated intermittently. In the control device of the resistance welding machine configured as described above, the energizing time of the welding current of a plurality of welding points in one welding cycle of the time setter which is output for each input of the start signal is integrated, and the integrated value and one welding Usage rate calculating means for calculating the usage rate from the cycle time and a plurality of welding current values in one welding cycle of the current setting device output for each input of the start signal are integrated, and an average welding current at one welding point A current accumulating means for calculating a value, a characteristic data storage means for storing an allowable usage rate characteristic for the current value, and an allowance for an average welding current value calculated by the current accumulating means from the storage means. A controller for a resistance welding machine, comprising: a usage rate reading unit, a determination unit that compares the allowable usage rate with the usage rate calculated by the usage rate computing unit, and determines whether the usage rate is good or bad. .