JPH01118377A - Controller for resistance welding machine - Google Patents

Abstract

PURPOSE:To easily check whether or not the activity ratio is the allowable activity ratio by comparing the activity ratio calculated by an activity ratio arithmetic means with the allowable activity ratio with respect to a set average welding current value of one welding cycle read out from a storage means. CONSTITUTION:Before a welding current is carried to a welding chip, a robot controller, etc., are actuated in a state with a switch 12 opened and a starting signal is produced for every welding point and the current value data of the welding current and the weld time data of each welding point are outputted from a current setter 1 and a time setter 2 as digital signals (i) and (t) in order. In addition, an activity ratio arithmetic circuit 8 calculates the activity ratio of one welding cycle from a starting pulse and the signal (t) of one welding cycle and a current integrating circuit 9 calculates the average welding current value of one welding cycle from the signal (i). A decision circuit 11 compares the allowable activity ratio with respect to the average welding current value read out from a memory 10 with the activity ratio calculated by the arithmetic circuit 8 and when the activity ratio is less than the allowable activity ratio, it is desplayed as superiority and when the ratio is more than the allowable ratio, it is displayed as inferiority.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is directed to a welding current circuit in which the usage rate of a rectifier diode, a current control transistor or thyristor, or a welding transformer is within an allowable range. The present invention relates to a control device for a resistance welding machine that starts post-welding after confirming that a certain condition exists, and protects the diode, transistor, silicon risk, etc.

(Prior art) Conventionally, in response to a start signal from a robot controller that occurs intermittently, a welding current of a current value and energization time set by a current setting device and a time setting device is intermittently applied to a welding current circuit. When sequentially welding several welding points in one summer using a resistance welding machine control device that is energized, use of rectifier diodes, current control transistors, thyristors, etc. inserted in the welding current circuit. The interval between the activation signals is set so that the usage rate is less than the allowable usage rate to prevent damage to transistors, diodes, etc.

(Problem to be solved by the invention) The above-mentioned work requires skill, and if the usage rate is mistakenly set to an excessive value, it may cause the inconvenience of burning out the diode, transistor, or thyristor. .

It is an object of the present invention to solve these conventional disadvantages.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a current setting device and a time setting device that are set by a current setting device and a time setting device in response to a starting signal from a robot controller etc. that is generated intermittently. In a control device for a resistance welding machine in which a welding current having a current value and a welding time is intermittently applied to a welding current circuit, the time setting device outputs a plurality of welding currents in one welding cycle each time the start signal is input. a usage rate calculation means that integrates the application time of welding current at a welding point and calculates a usage rate from the integrated value and the time of one welding cycle; and one welding current setting device that outputs an output every time the start signal is input. a current integrating means for integrating a plurality of welding current values in a cycle to calculate an average welding current value for one welding point; a characteristic data storage means for storing allowable usage rate characteristics with respect to the current value; and determining means for reading an allowable usage rate for the average welding current value calculated by, comparing the allowable usage rate with the usage rate calculated by the usage rate calculation means, and determining whether the usage rate is good or bad. It is characterized by

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

Next, without applying welding current to the welding current circuit, a robot controller or the like is operated to sequentially generate start signals.

The determining means compares the usage rate calculated by the usage rate calculation means with the allowable usage rate for the set average welding current value in the welding cycle read from the storage means, and determines whether the usage rate is less than or equal to the allowable usage rate. Determine if it is above. When the usage rate is determined to be below the allowable usage rate, the welding current having the current value and energization time set by the current setting device and time setting device is passed through the welding current circuit. If the usage rate is greater than or equal to the allowable usage rate,
Correct the time interval of the activation signal generated from the robot controller, etc. again.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of one embodiment of the invention.

In the figure, 1 is a current setting device for setting the welding current to be applied to a plurality of welding points, 2 is a time setting device for setting the welding current application time, and the current setting device 1 and time setting device 2 are, for example, a robot controller. It is connected to the current control circuit 3, and is configured to output digital signals i and t of current value data and energization time data set each time a starting signal a is input. The current control circuit 3 is connected between a DC power source (not shown) and a control pole of a current control element 4 of a transistor or thyristor, and a current control cord 4 connected to an AC power source (not shown) is connected to a current control cord 4 via a welding transformer 5. The current control circuit 3 adjusts the welding current detected by the current transformer 7 connected to the secondary side (or primary side) of the welding transformer 5 to the current setting. The time setting device 1 sets the welding current value at each welding point in the welding cycle, and the time setting device 2 sets the welding time at each welding point in the welding cycle. The circuit of the control device constituted by the current setting device 1 and the like is not particularly different from the conventional one.

The device of the present invention includes a usage rate calculating circuit 8 as the usage rate calculating means, a current integrating circuit 9 as the current integrating means, a memory 10 as the characteristic data storing means, and a determining means in addition to the above-mentioned conventional circuits. A determination circuit 11 is connected, and a switch 12 is interposed and connected to a connection circuit between the current control circuit 3 and the control pole of the current control element 4.

The usage rate calculation circuit 8 integrates the energization time data output from the time setting device 2, and calculates one welding time from the start pulse p of one welding cycle and the start pulse p of the next welding cycle input from the robot controller, for example. The current integration circuit 9 is configured to calculate the cycle time and calculate the usage rate in one welding cycle from the time and the integrated value, and the current integration circuit 9 integrates the current value data output from the current setting device 1. The integrated value is divided by the number of welding points in one welding cycle to calculate the average welding current value. Further, the memory 10 stores allowable usage rate characteristics of diodes, transistors, etc. with respect to current values as shown in the second diagram, and the determination circuit 11 stores the allowable usage rate characteristics of diodes, transistors, etc. with respect to current values as shown in the second diagram.
The permissible usage rate for the average welding current value calculated in is read from the memory 10, and the permissible usage rate is compared with the usage rate calculated by the usage rate calculation circuit 8. If so, it is determined to be good or bad and this is displayed on the display 13.

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

First, set the current value and energization time of each welding current to be applied to multiple welding points in one welding cycle in the current setting device 1 and time setting device 2, and also set the generation time interval of the start signal generated from the robot controller etc. do.

Next, before operating the robot controller or the like to flow welding current to the welding tip, if the robot controller or the like is operated with the switch 12 open, that is, with no welding current flowing to the welding tip, a start signal is generated for each welding point. is generated, and in response to the activation signal, current value data and energization time data of the welding current at each welding point are sequentially output from the current setting device 1 and time setting device 2 as digital signals i and t. The usage rate calculation circuit 8 calculates the start pulse f of one welding cycle.
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 determination circuit 11 compares the allowable usage rate for 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 when the usage rate is equal to or higher than the allowable usage rate, the display 13 displays that the usage rate is poor. When the usage rate is good, the operator closes the switch 12 and starts operating the robot controller again. If the usage rate is poor, the interval between activation signals of the robot controller is corrected, and the process is checked again to see if the usage rate has fallen below the allowable usage rate, and the process is repeated until the usage rate falls below the allowable usage rate.

In the above embodiment, the usage rate calculation circuit 8, the current integration circuit 9
and the determination circuit 11 are used, but these can be replaced by a computer.

(Effects of the Invention) As is clear from the above description, according to the present invention, an operator can set the current value and energization time of the welding current at each welding point in one welding cycle on the current setting device and the time setting device. When the time for one welding cycle is set, it is possible to easily check whether the usage rate of transistors, etc. in that welding cycle is below the allowable usage rate before welding starts.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing allowable usage rate characteristics with respect to current values. 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 A Shizuki → 1b

Claims (1)

[Claims] A resistor configured to intermittently energize a welding current circuit with a welding current of a current value and energization time set by a current setting device and a time setting device in response to a start signal from a robot controller, etc. that occurs intermittently. In the welding machine control device,
A usage rate that integrates the welding current application time of a plurality of welding points in one welding cycle of the time setting device output every time the start signal is input, and calculates the usage rate from the integrated value and the time of one welding cycle. a calculation means; a current integration means for calculating an average welding current value for one welding point by integrating a plurality of welding current values in one welding cycle of the current setting device output each time the start signal is input; a characteristic data storage means for storing allowable usage rate characteristics; and a permissible usage rate for the average welding current value calculated by the current integration means is read from the storage means, and the permissible usage rate and the allowable usage rate calculated by the usage rate calculation means are read out from the storage means. 1. A control device for a resistance welding machine, comprising a determination means for comparing the usage rate with a usage rate and determining whether the usage rate is good or bad.