JP2584300B2 - Automatic setting device for spot welding conditions - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] The present invention allows a welding condition to be automatically set by inputting data of a material to be welded, to perform spot welding, and to monitor a welding condition. The present invention relates to a spot welding condition automatic setting device for resetting welding conditions accordingly and automatically performing 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 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. Thus, nugget formation can be measured with high accuracy without affecting productivity, and abnormalities due to corona bonds generated 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 Japanese Patent Application No. 63-53811, the applicant of the present application automatically sets the welding conditions upon inputting the material to be welded, and resets the welding conditions based on the monitor data immediately after the end of welding by the above-described monitoring method. We have proposed a spot welding condition automatic setting device that automatically performs spot welding. Thus, when welding target material data is input, spot welding in which welding conditions are automatically set becomes possible. However, when the welding conditions are changed due to a chronological cause or the like, the resetting of the welding conditions is automatically performed, but such a resetting operation must be performed at each spot or each time a new welding is performed. Was left.

Accordingly, an object of the present invention is to provide an automatic spot welding condition setting device in which welding conditions set in response to input of work piece data are corrected and held according to the results of welding operations.

[Means for solving the problem]

In order to achieve this object, the present invention is, as shown in FIG. 1, the electrodes 2a, which are pressed by a pressurizer 3 capable of controlling the pressurization value and sandwich the workpieces 1a, 1b. Welding current control means that allows welding current to flow for a predetermined time after pre-energization from the AC power supply to 2b, and that allows monitor current to flow immediately after this welding current is applied, and that enables switching control of the welding current value. 4, a resistance parameter calculating means 5 for calculating a resistance parameter between the electrodes 2a, 2b when the monitor is energized based on a current and a voltage between the electrodes 2a, 2b, and a resistance parameter and a reference value set experimentally in advance. Welding state determining means 6 for comparing and determining whether the deviation is within an allowable range, welded material data input means 7 for inputting welded material data by external setting, and at least welding to the welded material data. Standard including current value and pressurized value Memory 8 for storing welding condition data and modified welding condition data obtained by modifying the data.
If the welding state determination means 6 determines that the welding is failed, the welding condition data creating means 9 for setting at least the welding current value that is stepwise raised and the work piece data input by the work piece data input means 7 are set. Is searched in the memory 8 as the modified welding condition data, and if it is stored, the associated modified welding condition data is output. If not stored, the associated reference welding condition data is output. And a memory control means 10 for storing the modified welding condition data created by the modified welding condition data creating means 9 and determined to be OK by the welding state determining means 6 in the memory 8.

[Action]

When welding material data is input by the welding material data input means 7, the memory control means 10 searches whether or not the corresponding welding condition data is stored in the memory 8 as corrected welding condition data. Is output to the pressurizer 3 and the welding current control means 4 if the reference welding condition data is not stored.
Immediately after the welding current is supplied by the welding current control unit 4, the monitor current is supplied, and the resistance parameter calculation unit 5 calculates the resistance parameter. The welding state determination unit 6 determines whether the deviation is within an allowable range. Let it. If the determination is OK, the operation ends. If the judgment result is NG,
The modified welding condition data creating means 9 creates the modified welding condition data and causes the welding operation to be performed again. If the modified welding condition data is not acceptable, the modified welding condition data is further raised and the welding operation is repeated. If OK, the modified welding condition data is stored in the memory 8 by the memory control means 10.

(Example of the invention)

FIG. 2 is a diagram showing an apparatus for automatically setting spot welding conditions according to one embodiment of the present invention.

In the same figure, an AC power source is provided in a state where the materials to be welded 11a and 11b are sandwiched between electrodes 12a and 12b pressurized by a pressurizer 16.
Spot welding is performed by supplying a welding current from 13 via a transformer 14.

Numeral 15 denotes a welding current control means for starting the current by a welding start signal, and sequentially carries out preliminary energization, energization of a set cycle of welding current, and immediately thereafter energization of one to several cycles of monitor current. The welding current control means is capable of switching control so that the welding current can be ranked up to, for example, 10 steps, and the pressurizer 16 can also switch the pressing force to, for example, 3 steps in accordance with the ranking of the welding current. Has become.

Reference numeral 20 denotes an electronic computer, for example, a personal computer, which comprises a welding condition memory for storing reference welding condition data and corrected welding condition data together with the I / O interface 21, and constitutes a memory control means thereof. Reference numeral 22 denotes a keyboard attached to the computer 20 and serving as welding data input means, and inputs the material of the welding material, the plate thickness, the number of sheets to be fitted, the presence or absence of a sealer and the like. As shown in FIG. 3, the memory of the electronic computer 20 stores reference welding condition data relating to the welding current, welding cycle and electrode pressing force with respect to the material and plate thickness of the material to be welded, The modified welding condition data created by the computer 30 is stored as a table. Then, the computer 20
The welding condition data of the material to be welded input by the keyboard 22 is searched, and the correction data or the reference data if none is supplied to the microcomputer 30 through the I / O interface 31. Also, when the material to be welded which is not prepared in advance as a table is input, standard welding condition data is calculated according to a predetermined program based on the related existing welding condition data and stored in a memory. Supply to computer 30. For example, if a seal is input, the welding current is increased by 20% compared to the presence or absence of the seal, and the electrode pressure is increased by 10%. In the case of three or more pieces, if there is no welding condition data, standard related welding data is created by calculating existing related data according to a predetermined program.

The microcomputer 30, together with the I / O interface 31, constitutes resistance parameter calculation means, welding state determination means, corrected welding data creation means, and the like. That is, JP 61
As disclosed in -71189, the resistance R itself detected based on the voltage and current between the electrodes 12a and 12b when the monitor current is applied, or the R calculated based on the similar resistance _R0 during the pre-application. / R ₀
Alternatively, a resistance parameter such as (R ₀ −R) / R ₀ is calculated.
Further, it is determined whether or not the deviation of the resistance parameter from the reference value is within an allowable range. Further, each time the result of the determination is NG, the set welding current value is raised by, for example, 2% to generate corrected welding data, and when this data is determined to be OK, through the I / O interface 21, The data is stored in the welding data memory of the electronic computer 20.

The operation of the spot welding condition automatic setting device thus configured will be described with reference to the flowchart shown in FIG. The keyboard 22 is used to input, for example, spot welding of two 0.8 mm steel plates without seals. Electronic computer
Reference numeral 20 retrieves the corresponding welding condition data. If there is correction data, the correction data is sent to the microcomputer 30. If not, the reference data of 9 kA, 7 Hz, 200 kg · f shown in FIG. 3 is sent.

Thereby, the pressurizer through the microcomputer 30
Operating conditions are set in 16 and the welding current control means 15, and welding is started. At the same time, when welding material data not prepared as a table is input, standard welding condition data is created and stored according to a predetermined program based on the related existing welding condition data, and stored in the microcomputer 30. Send out. Immediately after one cycle, for example, a monitor current of about 1000 A similar to the preliminary current is applied for several cycles, and the welding voltage and welding current signal are taken into the microcomputer 30 through the I / O interface 31 for welding. The condition is inspected, and if NG, the current is increased by 2% and welding is performed again. If it is NG again
Increase the rank by 2% until it becomes OK. When it is determined to be OK, the welding current value data is transferred to the computer 20 and stored as corrected welding condition data. At the next spot, welding is performed with this correction data. Further, when welding another workpiece having the same material data to be welded, re-welding is not required by using such correction data unless there is a change over time.

〔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 end of the welding current application, it is possible to detect with high accuracy the formation of a nugget after escape from an unstable state in which a welding portion corona bond or spatter is generated by welding heat, and it is also possible to detect an abnormality due to a corona bond generated in a cooling process. After such an inspection is performed, in the case of NG, the welding data is automatically corrected and re-welded. Existing correction data is used for the workpiece, eliminating the need for rewelding. Correction data is automatically created even for a change in the characteristics of the welding device over time. In other words, only by inputting the material to be welded, highly reliable inspection of spot welding and setting of welding conditions based on the inspection are automatically and efficiently performed while monitoring immediately after the end of welding.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a spot welding condition automatic setting device of the present invention, FIG. 2 is a diagram showing a configuration of a spot welding condition automatic setting device according to an embodiment of the present invention, and FIG. FIG. 4 is a flowchart illustrating a part of a table of reference welding conditions and the operation of the apparatus according to the embodiment. 1a, 1b, 11a, 11b: material to be welded, 2a, 2b, 12a, 12b: electrodes.

Claims (1)

(57) [Claims] 1. A welding current is passed for a predetermined time after a pre-energization is performed from an AC power supply to an electrode pressurized by a pressurizer capable of switching and controlling a pressurization value and sandwiching a material to be welded. The monitor current is applied immediately after the application of the welding current, and the welding current control means for enabling the switching control of the welding current value is provided between the electrodes when the monitor is applied based on the current and voltage between the electrodes. Resistance parameter calculation means for calculating a resistance parameter; welding state determination means for comparing the resistance parameter with a reference value set experimentally in advance to determine whether a deviation is within an allowable range; Welding material data input means for inputting material data by external setting; reference welding condition data including at least the welding current value and the pressing force value with respect to the welding material data; A memory for storing welding condition data, and when the welding state determination means determines NG, the modified welding condition data for setting at least the welding current value that is stepwise raised for the welding current control means is created. Modified welding condition data creating means, and searching whether the welding condition data for the material to be welded input by the material to be welded data input means is stored in the memory as the modified welding condition data, and storing the data. The modified welding condition data to which it belongs, and the reference welding condition data to which it belongs if it is not stored, are output. Further, it is created by the modified welding condition data creating means, and judged as OK by the welding state determining means. Memory control means for storing the modified welding condition data obtained in the memory. Contact condition auto setting device.