JPH0616951B2 - Power control device for welding equipment - Google Patents

Description

The present invention relates to a power control device for a welding device.

(Prior Art) Conventionally, a welding current of an arbitrary set value is applied to a welding spot for a set time via a welding electrode, and the welding electrode is moved to apply a welding current of an arbitrary set value to the next welding spot. For example, a robot-controlled spot welding apparatus is known in which resistance welding is performed at a plurality of welding spots by flowing for an arbitrary set time.

(Problems to be Solved by the Invention) In the spot welding apparatus as described above, when the spot welding spots are set to 7 spots, welding of the energizing current, the energizing time, etc. is performed on each of these spots as shown in the following table. Conditions are set.

According to this table, the welding conditions are different for each welding point, and the thermal stress applied to the welding device is also different. Therefore, if this welding device is designed so that there is not a large margin in terms of heat, when the combination with the most severe welding conditions is applied, large heat stress is applied to the components such as the rectifier that configure the welding device. It causes the inconvenience of damage. Conversely, if the welding equipment is designed to have a thermal margin even in the most severe combination of welding conditions, there is too much thermal margin under normal operating conditions, which is considerably easier than the worst conditions, and the equipment is efficient. It causes the inconvenience that it is bad.

The present invention has been made in view of such inconveniences in the related art, and even if the welding conditions of each welding point are different and the thermal stress applied to the welding device is different, the components such as the streamer of the welding device are damaged. The purpose is to improve the working efficiency of the welding device.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes an inverter circuit interveningly connected to a connection circuit between a power source and a welding electrode, and welding is performed by controlling the inverter circuit. A welding current having an arbitrary set value is applied to the welding point through the welding electrode for an arbitrary setting time, and a welding current having an arbitrary setting value is applied to the next welding point after an operation pause time has elapsed from the end of energization of the welding current. In a power control device of a welding device that performs resistance welding to a plurality of welding spots by flowing for an arbitrary set time, a memory in which a welding current setting value and a conduction time setting value at each welding spot are stored, and welding at each welding spot And a timing means for setting an operation pause time for suppressing a temperature rise of the welding device corresponding to the current setting value and the energization time setting value, the control means comprising: A welding current of an arbitrary set value stored in the memory is flowed during the energization time of the arbitrary set value, and after the passage of the operation pause set by the timing means from the end of energization of the welding current to the next welding spot, It is characterized in that the inverter circuit is controlled so that the welding current of an arbitrary set value stored in the memory is flowed during a conduction time of the arbitrary set value.

(Operation) As shown in FIG. 1, after the welding current of an arbitrary set value flows from the circuit of the welding device to the welding spot via the welding electrode for an arbitrary set time, the set current and the set energization are performed. A welding current having an arbitrary set value flows to the next welding point for an arbitrary set time after the lapse of an operation pause time corresponding to the time and suppressing the temperature rise of the welding apparatus. Therefore, even if an electric current of an arbitrary set value intermittently flows for an arbitrary set time in the circuit of the welding device, heat is not accumulated in the components such as the rectifier that configure the welding device, and the temperature does not exceed the predetermined value. Does not rise.

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

FIG. 2 shows an embodiment of the present invention applied to a spot welding device.

In the figure, the spot welding device (1) is connected to the AC power supply (2).
To the rectifier (3), the filter circuit (4) connected to its output side, the inverter circuit (5), the welding transformer (6) connected to its AC output side, and its secondary side. A current detector (9) and a constant current control circuit (10) that drive and control the welding electrode (8) and the inverter circuit (5) that are connected to each other via a rectifier circuit (7). And a base drive circuit (11), with this configuration, the welding electrode (8)
A current of an arbitrary set value was made to flow to the spot welding spot of the work (12) interposed between them.

A known computer (13) as a control means was connected to the constant current control circuit (10). In the memory (14), the welding current value and energization time value of each spot welding spot set in advance,
An address corresponding to both the set current and the set energization time, an operation pause time (data) for suppressing a temperature rise of the welding device corresponding to the both designated at the address, a program, and the like are stored.

The operation rest time corresponding to the set current and the set time is
Under normal welding conditions, the time required for the robot to move from one spot welding spot to the next spot welding spot is set to be substantially zero or to a minimum. Under more severe conditions, it is necessary and sufficient according to the conditions. Set to a certain value.

In the figure, (15) is a CPU that performs arithmetic processing, (16) is a timer that operates by being set by the data about the operation pause time read from the memory (14), (17) Display, (18) ) Is an input / output port.

Next, the operation will be described.

When the present apparatus operates, the CPU (15) reads the welding current and energization time of one spot welding spot from the memory (14). From the welding current and the energization time, the address of the memory (14) storing the operation pause time corresponding to these is read from the memory (14) (step of the flow chart of FIG. 3). Then, the data about the operation rest time corresponding to the welding current and the energization time stored in this address of the memory (14) is read from this address (step). The timer (16) is set by this data (step), and when the operation pause time corresponding to the data elapses (step), the start signal of the next energization cycle from the timer (16) causes the input / output port (18) to be started. Via constant current control circuit (1
Enter in 0). Thus, the circuit (10) starts the next energization cycle, and the welding current of the set value read from the memory (14) flows through the welding circuit for the predetermined time read from the memory (14). The above operation is sequentially performed by the robot for each spot welding spot of the work (12) arranged between the electrodes.

FIG. 4 shows a flow chart of another embodiment of the present invention configured as a timing means by software.

The configuration of this embodiment is the same as that shown in the second illustration except that the timer 16 is not used.

The memory (14) was stored with data, programs, etc. regarding the welding current value and energization time value at each spot welding spot. In this embodiment, as shown in FIG.
CPU (15) adds welding current A (B ← B + A)
Is performed (step). Then, in step, a timing of Δt, for example, 1 millisecond is softly taken in the step, and it is judged in the step whether or not the welding is completed. The above steps are repeated until it is completed. Each time the step is repeated, the value of B on the left side before that is substituted into B on the right side of the equation of the step. Therefore, each time the step is repeated, B on the left side
Is A, 2A, 3A ... At step Δt
The B on the left side of the step is
It corresponds to the amount of heat generated in the equipment corresponding to the welding current and energization time. When it is determined that the welding is completed in the step, the process proceeds to the step. In steps and, the timing of the operation rest time until the start of the next energization cycle is taken.

In the step, a multiplication process of a total addition value B (total heat generation amount) of the energizing current A when the welding is completed and a coefficient K (0 <K <1) having a correlation with the cooling time constant is performed. The timing is set to Δt. After the elapse of the time of Δt, it is judged in the step whether or not the accumulated heat amount B has become equal to or less than the maximum allowable value Bm (that is, the maximum allowable temperature), and the step is repeated until it does not become less than Bm.

When it becomes less than Bm, the start signal of the next energization cycle is input to the constant current control circuit (10) through the input / output port (18). Thus, the circuit (10) starts the next energization cycle, and the welding current of the set value read from the memory (14) flows through the welding circuit for the predetermined time read from the memory (14).

The above operation is sequentially performed for each spot welding spot of the work.

(Effects of the Invention) According to the present invention, even if the welding conditions at the welding point are different and the thermal stress applied to the welding device is different, the welding device can be fully operated without damaging the components such as the rectifier of the welding device. In addition, it has an effect that the capability of the welding apparatus can be exhibited most efficiently.

[Brief description of drawings]

FIG. 1 is an operation explanatory view of the apparatus, FIG. 2 is a block diagram of one embodiment of the present invention, FIG. 3 is a flow chart thereof, and FIG. 4 is a flow chart of another embodiment. (1) …… Spot welding equipment, (5) …… Inverter circuit (13) …… Computer, (14) …… Memory (15) …… CPU, (16) …… Timer

Claims (1)

[Claims] 1. An inverter circuit interveningly connected to a connection circuit between a power source and a welding electrode, and by controlling the inverter circuit, a welding current having an arbitrary set value can be applied to a welding spot through the welding electrode. Welding in which a welding current is flown for a set time, and a welding current having an arbitrary set value is flown to the next welding spot for an arbitrary set time after the operation pause time has elapsed from the end of energization of the welding current to perform resistance welding at a plurality of welding spots. In the power control device of the equipment, the memory that stores the welding current setting value and the energization time setting value at each welding point and the welding current setting value and the energization time setting value at each welding point correspond to the suppression of the temperature rise of the welding equipment. And a timing means for setting an operation pause time for setting the welding current at an arbitrary set value stored in the memory at the welding spot. For a certain period of time, and after the lapse of the operation pause time set by the timing means from the end of energization of the welding current, the welding current of any set value stored in the memory is set at the next welding point. A power control device for a welding device, wherein the inverter circuit is controlled so as to flow during the energization time.