JPH0832365B2 - Spot welding condition automatic setting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention allows welding conditions to be automatically set to perform spot welding by inputting data of a material to be welded, and a welding state monitoring result can be displayed. The present invention relates to a spot welding condition automatic setting device that resets welding conditions accordingly and automatically performs re-welding.

[Problems to be solved by conventional technology and invention]

Conventionally, a welding apparatus for automatically adjusting a welding current and an electrode pressure by monitoring a welding state during a welding process is well known (Japanese Patent Application Laid-Open No. 57-127584). In this case, since the welding state after the completion of welding is not monitored, it is impossible to set precise welding conditions according to the result.

On the other hand, according to Japanese Patent Application Laid-Open No. 61-71189, the present applicant applies the monitor energization with the electrode connected and pressurized immediately after the end of the welding current energization, so that the monitor resistance itself between the electrodes or the preliminary energization is performed. There has been proposed a method for monitoring a spot welded portion for determining whether or not a resistance parameter such as a value obtained by comparing a resistance value at the time of monitoring and a resistance value at the time of monitoring is within an allowable range. As a result, nugget formation can be measured with high accuracy without affecting productivity, and anomalies due to corona bonds that occur during the cooling process can be detected. Further, when compared with the resistance at the time of preliminary energization, it is possible to make a high-accuracy judgment in consideration of the state of plate matching, the material of the material to be welded, and the plate thickness.

Therefore, according to the present invention, the welding condition is automatically set when the data of the material to be welded is input, and the spot welding is automatically performed by resetting the welding condition by the monitor data immediately after the welding by the above-mentioned monitoring method. An object is to provide an automatic welding condition setting device.

[Means for solving problems]

In order to achieve this object, the present invention provides a material to be welded (1) which is pressurized by a pressurizer (6) whose pressurization value can be switch-controlled.
The electrodes (2a, 2b) sandwiching a, 1b) are pre-energized from the AC power supply (3), then the welding current is passed for a predetermined time, and immediately after that, the monitor current is passed. At the same time, a welding current control means (5) capable of switching control of the welding current and a resistance parameter calculation means (7) for calculating a resistance parameter between the electrodes when the monitor is energized based on the current and voltage between the electrodes (2a, 2b). ), A resistance means and a reference value set experimentally in advance to compare the resistance parameter and a judgment means (8) for judging whether the deviation is within an allowable range, and a material to be welded (1a, 1b).
Welding material data input means (10) for inputting the data of the type, plate thickness and plate set, and the welding current value to the welding current control means (5) in response to the data set by this input means. The pressure value is set for the pressurizer (6) and the welding current control means (5) is stepwisely output each time the judgment means (8) outputs a judgment result out of the allowable range. The welding condition setting means (11) sets the welding conditions by setting the welding current value which is ranked up and setting the welding pressure value to the pressurizer (6) which is the same or which is ranked up.

[Action]

A welding condition setting means (11) sets a welding current and an electrode pressing force as welding conditions based on the welding material data externally set by the welding material data input means (10). The welding current control means (5), after performing the pre-energization, sets the welding current for a predetermined time and the corresponding electrode (2a, 2a,
Weld under the pressure of 2b).

The judging means (8) compares the resistance parameter calculated by the resistance parameter calculating means (7) with a reference value each time welding is completed, and terminates the welding operation if the resistance parameter is within an allowable range. If it is outside the allowable range, 1 for the welding condition setting means (11)
Set the welding conditions that have been stepped up and perform welding again.

Example of Invention

FIG. 1 is a view showing a spot welding condition automatic setting device according to an embodiment of the present invention.

In the figure, the materials to be welded 1a and 1b are spot-welded by being supplied with a welding current from an AC power source 3 through a transformer 4 while being sandwiched between electrodes 2a and 2b pressurized by a pressure device 6. Is done.

Reference numeral 5 denotes a welding current control means, which is started by a welding start signal and performs preliminary energization, energization of welding current for a predetermined time, and immediately after that, 1 to several cycles of monitor current. The welding current control means 5 is switchable and controllable such that the welding current can be ranked up to, for example, 10 steps for each input of an NG signal described later. The pressurizer 6 can switch the pressing force in, for example, three stages in response to the rank increase of the welding current when the NG signal is input.

Reference numeral 7 is a resistance parameter calculating means, which is disclosed in Japanese Patent Laid-Open No. 61-7118.
As disclosed in 9, the electrode 2 when the monitor current is energized
Resistance R itself detected based on voltage and current between a and 2b, or resistance such as R / R _o or (R _o -R) / R _o calculated based on similar resistance R _o during pre-energization Calculate the parameters.

Reference numeral 8 is a judging means for judging whether or not the deviation of the resistance parameter from the reference value is within an allowable range and outputting an OK or NG signal. Reference numeral 9 denotes a display means including an OK lamp and an NG lamp for displaying the determination result.

Reference numeral 10 is a panel-operated material-to-be-welded data input means for inputting the type of the steel sheet to be welded, the plate thickness, and the data of the plate set. On this panel surface, a starting switch 10a, a soft steel plate (SPC), a selection switch 10b for indicating one of high-tensile steel plate and several kinds of plated steel plates, a numeric keypad 10c for indicating the plate thickness, and a two-piece combination. A selection switch 10d or the like for instructing the number of plate sets of steel plates, such as a combination of three plates, is arranged.

11 is a welding current value and electrodes 2a, 2b for a predetermined time
Is a welding condition setting means for outputting a control signal for setting the pressurization value. This means is composed of a CPU, and the attached RAM has a welding current value of 10 steps and a corresponding pressurization value of 3 steps for each combination of steel plate type, plate thickness and plate set, which are the data of the material to be welded. Are stored as a table. Then, when the activation switch 10a is operated,
The welding condition of the lowest rank of the material to be welded data set by the material to be welded data 10 is sent to the welding current control means 5 and the pressurizer 6, and every time an NG signal is input from the determination means 8, one step Welding conditions that have been upgraded one by one are sent out.

The operation of the spot welding condition automatic setting device configured as described above will be described with reference to FIG.

The material is SPC and the thickness is 0.8mm. First, the welding material data input means
By operating the ten selection switches 10b and 10d and the ten key 10c, such welding material data is set. The welding condition setting means 11 searches the above-mentioned table and sets the welding condition corresponding to the set welding material data. As a result, when the start switch 10a is operated, the welding current control means 5 supplies a preliminary current of about 1,000 A for one cycle, and then the welding time is set to 12 cycles of 50 Hz, and the welding current is 9,000 A,
Welding is performed under the welding conditions of the electrode pressure of 200 kg by the pressurizer 6. Immediately after that, for example, after one cycle has passed, a monitor current of about 1,000 A, which is similar to the preliminary current, is supplied for several cycles.

At that time, the resistance parameter calculating means 7 calculates the resistance parameter, and the judging means 8 compares the calculation result with a reference value. If it is within the allowable range for the reference value,
The display unit 9 displays OK and the welding operation is ended.
If it is out of the allowable range, NG is displayed and the welding condition of the welding material data set in the welding condition setting means 11 is set to be upgraded by one step. As a result, the welding current control means 5 increases the welding current by, for example, 200 A, and the pressurizer 6 performs welding again while keeping the electrode pressing force in the same state. If it is NG, the welding current will be further increased.
Increase 200A and increase electrode pressure by 50kg.

In this way, every time the NG signal is input, the rank of the welding condition is increased by one step. The welding operation is terminated when the rank becomes OK in the middle or when the highest rank in the 10th stage does not become OK.

When the data of the material to be welded is changed by the panel operation on the material to be welded data input means 10, the welding is performed with another current and pressurization value which are also set again, and when the NG signal is input, only the predetermined step value is ranked. Re-welding is performed under the increased welding conditions.

〔The invention's effect〕

As described above, according to the present invention, when the workpiece data is input,
The welding conditions are automatically set and spot welding is automatically performed. Immediately after the welding current is applied, it is possible to detect with high accuracy the nugget formation after the escape of the unstable condition of the weld corona bond or spatter generation due to the welding heat, and the abnormality due to the corona bond that occurs during the cooling process can be detected. After a high inspection, in the case of NG, the welding conditions automatically upgraded are reset.

That is, only by inputting the data of the material to be welded, it is possible to perform highly reliable automatic welding of spot welding while monitoring immediately after the welding is completed.

[Brief description of drawings]

FIG. 1 is a diagram showing the construction of an automatic spot welding condition setting device according to an embodiment of the present invention, and FIG. 2 is a flow chart for explaining the operation thereof. 1a, 1b …… Material to be welded, 2a, 2b …… Electrodes.

Claims (1)

[Claims] 1. A welding current is passed only for a predetermined time after pre-energizing from an AC power source to an electrode which is pressed by a pressurizer capable of switching and controlling a pressurization value and sandwiches a material to be welded. Then, the monitor current is supplied immediately after the welding current is supplied, and the welding current control means for switching and controlling the welding current value and the resistance parameter between the electrodes when the monitor is energized are based on the current and voltage between the electrodes. A resistance parameter calculating means for calculating, a judging means for judging whether or not a deviation is within an allowable range by comparing the resistance parameter with a reference value set experimentally in advance, the kind of the material to be welded, Welding material data input means for inputting plate thickness and plate set data by external setting, and setting the welding current value to the welding current control means in response to the set data, and setting it in the pressurizer. In contrast to the above The pressurizing value is set, and the welding current value which is stepwise ranked higher than the welding current control means is set each time the judgment result out of the allowable range is output from the judging means. And a welding condition setting means for setting the welding condition by setting the welding pressure value which is the same or stepwise increased with respect to the spot welding condition automatic setting device.