JPH0714555B2 - Controller for resistance spot welder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a resistance point welding machine, and in particular, a resistance point suitable for appropriate conditions in which each of welding current, energization time, and pressure is suitable for the shape of the electrode tip. A control device for a welding machine.

[Conventional technology]

With the conventional welding current automatic adjusting device, the welding quality becomes unstable when the current tip of the spot welding machine is consumed.
The welding current is increased step by step with the welding point. For example, Japanese Patent Publication No.
There are two methods: step, up and control as shown in Japanese Patent Publication No. 57-7034 and linear, up and control as shown in Japanese Patent Publication No. 57-7034.

It is well known that, in general, the most important point for stabilizing the welding quality in spot welding is a method of compensating for the consumption of the current tip diameter. In order to compensate for this, conventionally, control has been performed to increase the welding current in proportion to the wear of the electrode tip diameter.

[Problems to be solved by the invention]

In order to ensure stable welding quality, there are appropriate welding conditions depending on the electrode tip diameter. However, conventionally, only the welding current is controlled for the electrode tip diameter, so the other conditions, such as energizing time and pressure, are the electrode tip diameter usage range (new to worn). Since it is set with an appropriate condition value for the intermediate diameter of the, when the electrode is new, dust and burrs are likely to occur, and when the electrode is consumed due to use, fraying of the welding location often occurs, and dust It had a drawback that it was not possible to control welding with good precision without causing burrs or flakes. For this reason, conventionally, the condition pattern of automatic welding current control is often changed by trial and error.

[Object of the Invention]

An object of the present invention is to provide a control device for a resistance spot welding machine that can always obtain good welding quality regardless of the degree of wear of the welding electrode.

[Means for solving problems]

The present invention sets a welding point number detecting means for counting the number of welding points, a first welding current setting means for setting a welding current initial condition for the number of welding points, and a welding current condition corresponding to each predetermined number of welding points. The second welding current setting means, the welding point number detecting means, the first welding current setting means, the first calculation control circuit for calculating the welding current condition from the second welding current setting means, and the welding point energization First to set time initial conditions
Second energization time setting means for setting the conditions of the energization time corresponding to each predetermined number of welding points, the number of dot detection means, the first energization time setting means, and the second energization time setting A second arithmetic and control circuit for calculating the energization time condition from the means, a first pressing force setting means for setting an initial condition of the pressing force of the number of welding points, and a pressing force condition corresponding to each predetermined number of welding points are set. And a third arithmetic and control circuit for calculating a pressing condition from the second pressing force setting device, the hitting point number detecting device, the first pressing force setting device, and the second pressing force setting device. It is what

〔Example〕

 Examples of the present invention will be described below.

FIG. 1 shows an embodiment of the present invention.

In the figure, a start switch S has a preload time control circuit 1 for setting a time until a predetermined pressurizing force is applied to a workpiece by upper and lower electrodes, and an electrode pressurizing force control for setting a pressurizing force applied to an electrode. The circuit 5 is connected. Further, an energization time control circuit 2 for setting a time for supplying a welding current to the welding electrode is connected to the preload time control circuit 1, and the energization time control circuit 2 applies pressure to the welding electrode after energization. A holding time control circuit 3 for setting a holding time is connected. A welding current control circuit 4 for setting a welding current is connected to the preload time control circuit 1. The welding current control circuit 4 is configured to receive the output of the energization time control circuit 2. The output of the holding time control circuit 3 is input to the electrode pressurization control circuit 5.

On the other hand, the spot detector 14 that detects the welding spot by the welding electrode
Is provided, and the dot detector 14 has a first and a second
And the third arithmetic and control circuits 11, 8 and 13 are connected. The count value of the dot number counter 15 that counts the detected value is configured to be input to each of the arithmetic circuits 11, 8, and 13, respectively. The dot detector 14 and the dot counter 15 constitute dot number detecting means. This first arithmetic control circuit 11
A first welding current setting circuit 10 and a second welding current setting circuit 17, which will be described later, are connected to the. Further, a first energization time set value circuit 7 and a second energization time set value circuit 16 which will be described later are connected to the second arithmetic control circuit 8. Further, a first pressurizing force setting circuit 12 and a second pressurizing force setting circuit 18, which will be described later, are connected to the third arithmetic control circuit 13. The first arithmetic control circuit 11 causes the welding current control circuit 4 to
The second arithmetic control circuit 8 controls the energization time control circuit 2 and the third arithmetic control circuit 13 controls the electrode pressure control circuit 5. A set value circuit 9 is connected to the holding time control circuit 3, and the output of the holding time control circuit 3 is input to the electrode pressing force control circuit 5.

Next, the operation will be described. First, turn on the start switch S
Then, the preload time control circuit 1 and the electrode pressure control circuit 5 operate, and the upper and lower electrodes apply a pressure to the workpiece. The applied pressure is controlled by the preload time control circuit 1, the energization time control circuit 2, and the holding time control circuit 3 in order to advance the preloading, energizing, and holding in sequence at a preset time, during which the electrode presses the workpiece. The pressure is released, and the pressurization is released when the holding time of the holding time control circuit 3 ends. On the other hand, the welding current control circuit 4
The energization time control circuit 2 is operating during the operation period, and the welding current flows while the welding current control circuit 4 is operating.
Here, the conditions of welding current, energizing time, and pressure at each welding point are set as shown in the pattern of FIG. This pattern is a basic control pattern for the welding current, the energization time, and the number of welding points of the applied pressure. The welding current is increased due to the consumption of the electrode tip diameter, and therefore is increased to compensate for the decrease in current density. The energization time is delayed by the electrode enlargement as is the case with the welding current, and the nugget generation timing is delayed. Since the current density is concentrated when the electrode is new, the pressure is increased to prevent dust and burrs, and is gradually decreased.

As described above, the set values of welding current, energizing time, and welding pressure are made to correspond to the welding spots in order to control the welding current, energizing time, and welding pressure at each welding spot in the pattern shown in FIG. To change. That is, a sequence signal such as a start switch for identifying welding spots, or a detector 14 for detecting the number of welding spots composed of a welding current detector (CT or shunt, etc.) and welding obtained by the detector 14 RBI counter that counts RBI
15, the first welding current set value circuit 10 for setting the initial condition of the welding spot, and the second welding current set value circuit for setting the corresponding condition for each predetermined number of welding spots if the welding current is 15, for example. 17, the counter 15 and two set value circuits 10, 17
The welding current pattern shown in FIG. 2 is obtained by controlling the setting circuit of the welding current control circuit 4 which is composed of the first arithmetic control circuit 11 for calculating the condition more suitable for each hit point.

Similarly, the energization time is the welding spot number counter 15, the first energization time set value circuit 7 for setting the initial conditions of the welding spot, and the second energization time setting circuit for setting the condition corresponding to each predetermined welding spot number. With the set value circuit of 16, the welding pressure is set to the welding spot number counter 15, the set value circuit 12 for setting the initial condition of the welding spot, and the condition corresponding to each predetermined number of welding spots. Each of the value circuits is set to have the pattern of the control shown in FIG. 2, and is controlled by the energization time control circuit 2 and the electrode pressure control circuit 5. In addition,
The set value circuits 6 and 9 are circuits for setting the conditions of the preload time control circuit 1 and the holding time control circuit 3.

〔The invention's effect〕

As described above, according to the present invention, the three major welding conditions suitable for the tip shape of the welding electrode can be selected, so that better stabilization of the welding quality can be obtained.

Further, according to the present invention, each welding condition can be set to an optimum value, so that the life of the welding electrode can be improved.

Further, according to the present invention, the selection range of welding conditions such as selection of energization time and pressure can be widened, and the selection of condition patterns can be facilitated.

As described above, according to the present invention, it is possible to always obtain good welding quality regardless of the degree of wear of the welding electrode.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing a control pattern. 1 ... Preload time control circuit, 2 ... Energization time control circuit, 3
...... Holding time control circuit, 4 ... Welding current control circuit, 5 ...
... Electrode pressure control circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-55-126389 (JP, A) Sekikai-A 49-50521 (JP, U) JP-B 58-29194 (JP, B2) JP-B 57- 7034 (JP, B2)

Claims (1)

[Claims] 1. A welding number detecting means for counting the number of welding points, a first welding current setting means for setting a welding current initial condition for the number of welding points, and a welding current condition corresponding to each predetermined number of welding points. The second welding current setting means to be set and the number-of-welding-points detecting means, the first welding current setting means, the first calculation control circuit for calculating the welding current condition from the second welding current setting means, and the number of welding points First to set the initial conditions of energization time
Second energization time setting means for setting the conditions of the energization time corresponding to each predetermined number of welding points, the number of dot detection means, the first energization time setting means, and the second energization time setting A second arithmetic and control circuit for calculating the energization time condition from the means, a first pressing force setting means for setting an initial condition of the pressing force of the number of welding points, and a pressing force condition corresponding to each predetermined number of welding points are set. And a third arithmetic and control circuit for calculating a pressing condition from the second pressing force setting device, the hitting point number detecting device, the first pressing force setting device, and the second pressing force setting device. Control device for resistance spot welder.