JPH0732956B2 - Method and device for determining quality of welding work in resistance welding - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method and apparatus for monitoring voltage or current waveforms in resistance welding to determine the quality of welding.

[Technical background of the invention]

For example, in order to provide a lead on an electric component with a lead, for example, a resistor, both ends of a ceramic body are covered with iron caps, and end portions of lead wires are brought into contact with the respective caps and resistance welding is performed.

In this case, it is already known that the lead wire must be firmly fixed to the cap both mechanically and electrically, and the quality of the fixed state can be determined by what the voltage or current waveform at the time of welding was. Has been.

FIGS. 6A and 6B show two typical examples. First, in the case of FIG. 4A, the voltage or current waveforms for S non-defective workpieces are stored, and the average value V _ave is calculated and used as the reference waveform. Then, the fluctuation range is artificially set around this reference waveform and the maximum value V _max and the minimum value V
_{Find min} . A region between the maximum value V _max and the minimum value V _min is a region for which the quality is judged, and if it is out of this region, it is determined as a defective product.

However, in the method of FIG. 6 (a), the allowable range tends to be too large, and a defective product may be determined to be a good product.

On the other hand, FIG. 6 (b) shows the maximum value Vmax and the smaller value when the maximum value waveform is formed by storing the waveform including the maximum value Vmax and the waveform including the minimum value Vmin twice each. The area between the minimum value Vmin and Vmin is a non-defective area.

However, in the method of FIG. 6 (b), the maximum value V
_If a situation occurs in which _max falls below the minimum value V _min as indicated by the broken line, there is the inconvenience that the non-defective product will not be determined for this range. That is, although the waveform shown by the broken line contains some defective elements, it can be handled as a non-defective product without any problem. Thus It must be re-stored waveform that does not exceed the maximum value V _max of the maximum value V _max, as shown by the broken line as the minimum value V _min if it for use, if the leverage minimum value V _min It is necessary to remember the maximum value V _max again. In short, it is complicated to select the work to be stored in the waveform.

[Object of the Invention]

The present invention has been made in consideration of the above points, and it is an object of the present invention to provide a waveform determining method and apparatus for resistance welding, which can accurately determine quality and can easily set waveform data used for determination. To aim.

[Outline of Invention]

For this purpose, in the present invention, waveforms are stored a predetermined number of times for each of the maximum and minimum values of welding voltage or current for a plurality of non-defective workpieces. The maximum value is larger and the minimum value is smaller. Then, if the maximum value is greater than the minimum value by a predetermined value or more, the waveform data is set as it is, and if it is less than the predetermined value, the reference waveform data obtained by correction is used to judge the quality of the welded work. It's something that you do.

As a result, basically, it is possible to set the waveform by using the waveform data itself taken out when welding the workpiece.

As a result, basically, it is possible to set the waveform by using the waveform data itself taken out when welding the workpiece.

〔Example〕

The present invention will be described below with reference to FIGS. 1 to 5 with reference to an embodiment.

FIG. 1 shows a welding voltage waveform suitable for explaining the waveform data setting in the present invention, where H _i is the maximum value and L ₀
Is the minimum value. The maximum value and the minimum value are set above and below the reference value, respectively.

Then, a part of the maximum value H _i is lower than the minimum value L ₀ . That is, since the maximum value and the minimum value of such a relationship cannot be used as they are, it is necessary to correct them.

FIGS. 2 (a) and 2 (b) show how to make this correction. This correction is replaced by the maximum value H _i 'the waveform of the minimum value L ₀ is the portion of the minimum value L ₀ as shown in the diagram (a) exceeds the maximum value H _i, the minimum value L the maximum value H _{i Replace with 0} '. Then, since the width is 0 at the intersection of the maximum value H _i and the minimum value L ₀ just by performing the replacement, there is no allowable range obtained as the difference between the maximum value and the minimum value, which is inconvenient. is there.

Therefore, as shown in FIG. 6B, when the difference between the maximum value H _i and the minimum value L ₀ after partial replacement is within a predetermined value, the maximum value is set so that this difference becomes the predetermined value. Value H _i , minimum value
Correct each of L ₀ . This is because addition and subtraction are performed in equal amounts for each of the maximum value H _i and the minimum value L ₀ . As a result, the difference between the maximum value H _i and the minimum value L ₀ is always greater than or equal to the predetermined value, as indicated by the alternate long and short dash line in FIG.

FIG. 3 is a flow chart showing the operation of setting the reference waveform described with reference to FIGS. 1 and 2 (a) and (b), and this flow chart and therefore the following description will be given.

First, the welding apparatus for inputting the maximum value waveform and the state of the apparatus according to the present invention are set (S1). Then, the maximum welding voltage (or current) is applied to the work (S2), and the waveform at that time is sampled at microsecond intervals and stored (S2).
3). Such waveform reading is performed for N workpieces (S4).

Next, the same operation as in steps S1 to S4 is performed to input the minimum value waveform (S5 to S8). As a result, N waveforms are read for each of the maximum value and the minimum value.

In this state, check the welding finish condition for the 2N workpieces whose waveforms have been read, and if all are good, the operator is OK.
Input (S9), and if there is a defective product, enter NO.

When NO is input, the process returns to step S1, and when OK is input, the process proceeds to step S11 (S10). In this step S11, the maximum value and the minimum value of each N waveform are shown in FIGS. 2 (a) and 2 (b).
After performing the processing shown in, the maximum value among them is the standard value.
The same Min is obtained as Max and the minimum value (S11). This standard value M
ax and Min correspond to the waveform in which the maximum values H _i and H _i ′ are connected by the one-dot chain line and the minimum value L ₀ and L ₀ ′ are connected in the one-dot chain line in FIG.

Then, in steps S3 and S7, the difference between the standard values Max and Min is obtained for each point sampled at intervals of T microseconds (S12). If this difference is greater than or equal to the set value, the process immediately proceeds to step S17, but if it is less than the set value, steps S14 through S14.
After performing the process of S16, the process proceeds to step S17.

In step S14, the value obtained by subtracting the difference between the standard values Max and Min from the set value is obtained as A, and the value obtained by dividing this A in step S15 is B (S15), and this B is added to the standard values Max and Min. Or subtract (S16) to perform correction.

In step S17, from step S13 or step S16
The standard values Max and Min from are determined as the maximum standard value H _i and the minimum standard value L ₀ , respectively. Then, the processing of steps S12 to S17 is repeated for each point set at T microsecond intervals, and when the processing is completed for all points (S18), the operation is completed.

FIG. 4 shows an apparatus configuration for carrying out the method of the present invention. In this apparatus, 1 is a buffer, and when a welding voltage or current from a welding apparatus (not shown) is applied, it is adjusted to the input level of the sample holder 2 and applied to the sampling holder 2. The sample holder 2 samples the signal from the buffer 1 by giving a command signal from the CPU 5 at intervals of T microseconds, and the sampled value is sampled by the A / D circuit 3
Give to.

CP in reference waveform setting mode according to command from command unit 7
U5 starts to give the command signal to the sample holder 2 based on the signal given from the comparator 4 when the level of the input signal exceeds the predetermined value V _s . In this case, the command signal is generated in synchronization with the clock signal from the clock generator 6,
The obtained waveform data is stored in RAM8.

This waveform storage is performed N times for each of the maximum value and the minimum value according to the command from the command unit 7, and the CPU 5 uses the waveform data recorded in the RAM 8 to perform the data processing shown in FIG. 3 to obtain the reference waveform. .

After setting the reference waveform, respond to the command from the command unit 7.
The CPU 5 shifts to the judgment operation mode, and can judge the quality. That is, the CPU 5 determines whether or not the waveform given from the welding device as an input is within the standard value, and sends the determination result as an output.

FIG. 5 shows the configuration of an electric component sorting apparatus according to the present invention. In this apparatus, reference numeral 101 denotes a transfer drum which is provided with receiving recesses for accommodating electric components at equal intervals on its peripheral edge, and which is driven by a drive source (not shown) to rotate stepwise. When the parts are supplied to the parts, they rotate while they are housed, and when they are rotated to some extent, the electric parts are released by spontaneous fall.

Electrodes 102, 102 are provided at positions rotated from the component supply portion of the transfer drum 101 by a certain angle so as to come into contact with a pair of lead wires to be welded to the electrical component.
The lead wire is supported so as to come into contact with the cap of the electric component by the rotation of the rotating drum 101, and when reaching a predetermined position, welding is performed by the welding device 100. At this time, the electric component is pressed by the pressing plate 103 so as not to jump out from the receiving recess of the transfer drum 101.

The voltage or current waveform at the time of this welding is given to the discrimination device 110. The discriminating device 110 has the circuit configuration shown in FIG.

If a defective product can be determined from the detected waveform, an output is given to the shift register 120. The shift register 120 performs a shift operation in synchronization with a step rotation of the transfer drum 101 by a shift signal provided from a transfer drum drive circuit (not shown), for example, and the electric component reaches a reject position where the rejector 104 is installed. At this time, the output of the shift register 120 is given to the rejector 104 so that it is discharged to the tray 105.

The electric components that have not been removed at the reject position move on the transfer drum 101 to the natural drop position and slide down on the tray 106.

In this way, the quality of the electric parts is selected.

〔The invention's effect〕

As described above, the present invention, when the maximum value and the minimum value are selected from the maximum value and the minimum value of the welding voltage or current during the welding of non-defective workpieces that are stored in the waveform at predetermined times, the maximum value is the predetermined value rather than the minimum value. If it is larger than the above, the waveform data is set as it is, the part less than the predetermined value is corrected and the reference waveform is set, and the quality of the welding work is judged using this reference waveform. The reference waveform obtained from the waveform obtained from the work can be used, and a more accurate reference waveform can be obtained as compared with the conventional one in which the fluctuation range is artificially set. In addition, when the stored waveform is defective as the reference waveform, it is corrected to form the reference waveform.Therefore, it is possible to use a waveform captured compared to the conventional detected waveform itself as the reference waveform. The work is simple. Since the formation of the reference waveform is performed well in this way, it is possible to accurately determine the quality of welding of the work.

[Brief description of drawings]

FIG. 1 is a waveform diagram for explaining a welding waveform setting method in the present invention, FIGS. 2 (a) and 2 (b) are waveform diagrams showing a method for correcting waveform data, and FIG. 3 is described with reference to FIG. The setting method and the correction method described with reference to FIGS. 2 (a) and 2 (b) are continuously shown in a flowchart, FIG. 4 is a block diagram showing the circuit configuration of the device according to the present invention, and FIG. FIGS. 6 (a) and 6 (b) are explanatory views of a conventional method for detecting a current waveform, showing the structure of the mechanical portion of the device according to the invention. H _i ... maximum value, L ₀ ... minimum value, Max, Min ... standard value, T ... sampling processing time, S ... preset number, N ... preset number of times. 101 ... Transfer drum, 102 ... Electrode, 103 ... Presser plate, 104 ... Rejector, 105, 106 ... Saucer.

Claims (2)

[Claims] 1. A maximum value and a minimum value of a welding voltage or current are stored for a plurality of non-defective workpieces, and the maximum value of each waveform point among the stored waveforms is the maximum value of the welding voltage or current. The larger value from the middle and the minimum value take the smaller value from the minimum value of the welding voltage or current as a total waveform, and if the difference between the maximum value and the minimum value in this comprehensive waveform is a predetermined value or more, it is as it is. Waveform data is set, and if it is less than the specified value, it is corrected so that it becomes a specified value to form a reference waveform, and the waveform obtained from the workpiece to be inspected is compared with the reference waveform to determine whether it is acceptable Method for determining the quality of welded work in resistance welding. 2. A means for detecting the rise of the waveform of the welding voltage or current taken out from the work every time the work is welded, and a sample for taking out the value in the waveform for each predetermined section according to the output of the rise detecting means. The holder, a means for recording the maximum value or the minimum value every time the signal from the sample holder is given, and the maximum value and the minimum value in the waveform recorded in the recording means are separately integrated, and When the difference between the maximum value and the minimum value in the integrated waveform is less than the predetermined value, the maximum value waveform and the minimum value waveform are corrected and recorded as the reference waveform in the recording means, and the sample holder is stored. A device for judging the quality of a welded work in resistance welding, which comprises means for judging the quality by comparing with the reference waveform when the waveform to be inspected is given from.