CN-116921832-B - Splash detection method

Abstract

The present invention has been made to solve the problems, and an object of the present invention is to provide a splash detection method of spot welding, which is capable of detecting the occurrence of splash without resetting a voltage detection line. In order to solve the above problems, in the spot welding method, a pulse-shaped waveform welding current is supplied to a workpiece by alternately performing a step of maintaining the welding current within a set peak current range, a step of decreasing the welding current from the peak current range toward a bottom current, and a step of increasing the welding current toward the peak current range when an effective value of the welding current reaches within a set target range, in a plurality of cycles. In the sputtering detection method, pulse widths IW (1), IW (2) in respective periods of a pulse-like waveform are measured, and if a pulse width difference D (M) =iw (M) -IW (M-1) between the pulse width IW (M) in a target period (mth period) and the pulse width IW (M-1) in the preceding period thereof exceeds a width threshold Dth, the occurrence of sputtering is detected.

Inventors

• KODA TAKASHI
• Tan Xihao
• Qi Tengren
• WATANABE NOBUYA

Assignees

• 本田技研工业株式会社

Dates

Publication Date

20260505

Application Date

20220331

Claims (2)

1. 1. A spatter detecting method detects the occurrence of spatter in a spot welding method for joining a workpiece by supplying a welding current, The spot welding method includes the steps of maintaining the welding current within a predetermined peak current range, decreasing the welding current from the peak current range toward a bottom current, and increasing the welding current toward the peak current range when an effective value of the welding current reaches within a predetermined target range; in the spot welding method, a slope time of adding a current rising time from the bottom current to the peak current range and a peak maintaining time of maintaining the welding current in the peak current range is fixed, The pulse width of the foregoing pulse-like waveform in each period is measured, and when the difference between the pulse width in the target period and the pulse width in the preceding period of the target period exceeds a predetermined width, the occurrence of sputtering is detected.
2. 2. The splash detection method according to claim 1, wherein, When the occurrence of the splash is detected, the quality of the product manufactured by welding the aforementioned workpieces is estimated based on the timing at which the occurrence of the splash is detected.

Description

Splash detection method Technical Field The invention relates to a splash detection method. More specifically, the present invention relates to a splash detection method for detecting the occurrence of splash during spot welding. Background When a plurality of metal plates are welded, spot welding using a spot welding device is performed. In spot welding, a plurality of metal plates serving as workpieces are sandwiched between a pair of electrode chips, and a current is applied between the pair of electrode chips to cause nuggets to be generated between the plurality of metal plates, thereby welding the plurality of metal plates. In the spot welding method proposed by the applicant as shown in patent document 1, a pulse-like waveform welding current is supplied in a plurality of cycles in a state where a plurality of metal plates are sandwiched by a pair of electrodes, whereby the plurality of metal plates are welded. [ Prior Art literature ] (Patent literature) Patent document 1 International publication No. 2020/050011 Disclosure of Invention [ Problem to be solved by the invention ] However, in spot welding, during the supply of welding current to the metal plate, a phenomenon called "splash" occurs, i.e., a portion of the metal plate melts and flies. Since the occurrence of the spatter may lower the welding strength, it is preferable that the spatter is detected immediately when it occurs. Moreover, if such sputtering occurs, the voltage between the pair of electrode chips at that instant is drastically reduced. Therefore, in the conventional sputtering detection method, the occurrence of sputtering is often detected based on the voltage change between the electrode chips. However, in this case, it is necessary to provide a voltage detection line for detecting a voltage in the vicinity of the electrode chip, which may cause an increase in cost. The present invention aims to provide a splash detection method of spot welding, which can detect the generation of splash without resetting a voltage detection line. [ Means of solving the problems ] (1) The spatter detecting method of the present invention detects the occurrence of spatter in a spot welding method for joining workpieces (e.g., a workpiece W described later) by supplying a welding current. In the spot welding method, the welding current of a pulse waveform is supplied by alternately performing a step of maintaining the welding current within a predetermined peak current range, a step of decreasing the welding current from the peak current range toward a bottom current, and a step of increasing the welding current toward the peak current range when an effective value of the welding current reaches a predetermined target range. In the above-described sputtering detection method, the pulse width of the pulse-like waveform in each period (for example, a pulse width IW (N) described later) is measured, and if the difference between the pulse width in the target period and the pulse width in the period preceding the target period (for example, a pulse width difference D (M) described later) exceeds a predetermined width (for example, a width threshold Dth described later), the occurrence of sputtering is detected. (2) In this case, in the above-described method for detecting a splash, when the occurrence of a splash is detected, the quality of a product manufactured by welding the workpiece is preferably estimated based on the timing at which the occurrence of the splash is detected. (3) In this case, in the spot welding method, it is preferable that a slope time obtained by adding a current rising time from the bottom current to the peak current range and a peak maintaining time obtained by maintaining the welding current within the peak current range is fixed. (Effects of the invention) (1) If splash occurs during spot welding, the sheet resistance of the workpiece drops sharply. Therefore, if sputtering occurs while a pulse-shaped welding current is supplied to the workpiece to join the workpiece, the sheet resistance of the workpiece drops sharply, and even the time constant when the welding current drops from the peak current range to the bottom current becomes extremely long. Therefore, when the effective value of the welding current reaches the target range, current control is performed to increase the welding current toward the peak current range to supply the welding current having a pulse-like waveform, and at this time, the difference between the pulse width of the welding current in the period in which the sputtering is generated and the pulse width of the welding current in the period immediately before the sputtering is generated becomes large. In the present invention, by utilizing this phenomenon, the occurrence of splash can be detected without resetting the voltage detection line. Further, in the present invention, the occurrence of the spatter is detected based on the comparison of the pulse width in the target period and the pulse