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CN-122007585-A - Spot welding machine, control method, circuit and system

CN122007585ACN 122007585 ACN122007585 ACN 122007585ACN-122007585-A

Abstract

The invention belongs to the technical field of spot welder control, and discloses a spot welder, a control method, a circuit and a system, wherein the spot welder control method comprises the steps of monitoring contact resistance and/or spot welding pressure of a welded workpiece in real time; when the contact resistance is reduced to a preset resistance trigger threshold value and/or the spot welding pressure is increased to a preset pressure trigger threshold value, the spot welding pulse output is automatically triggered, whether the spot welding current exceeds a preset current upper limit or not is monitored in real time in the spot welding process, overcurrent protection is executed if the spot welding current exceeds the preset current upper limit, meanwhile, the health state of the MOS tube is monitored in real time, and if the damage of the MOS tube is detected, the output is immediately closed. Compared with the prior art, the invention realizes the omnibearing closed-loop quality control, proposes a real-time health detection and protection scheme of the MOS tube, has high integration level, low cost and flexible application, and can fill the technical blank of low-voltage heavy-current spot welding.

Inventors

  • YANG JIANJUN
  • LI XING

Assignees

  • 浙江水恩智能科技有限公司

Dates

Publication Date
20260512
Application Date
20260204

Claims (11)

  1. 1. A control method of a spot welder is characterized in that, the spot welder control method comprises the following steps: the judgment of the health state of the MOS tube is completed before spot welding; Monitoring the contact resistance and/or the spot welding pressure of the welded workpiece in real time to judge whether the triggering condition is triggered or not; When the contact resistance is reduced to a preset resistance triggering threshold value and/or the spot welding pressure is increased to a preset pressure triggering threshold value, automatically triggering spot welding pulse output; In the spot welding process, monitoring whether the spot welding current exceeds a preset current upper limit in real time, and if so, executing overcurrent protection; Meanwhile, the health state of the MOS tube is monitored in real time, and if the damage of the MOS tube is detected, the output is immediately closed; after the spot welding is finished, the energy release condition of the spot welding is obtained according to the data tested in the spot welding process, and then the quality of the spot welding is rapidly judged according to the resistance and the current condition.
  2. 2. The spot welder control method according to claim 1, characterized by comprising, before monitoring in real time the contact resistance and/or spot welding pressure of the welded workpiece: Acquiring a spot welding instruction; After a spot welding instruction is acquired, performing system self-checking to determine whether the voltage of a point welding head is in a normal range; And detecting whether the state of the MOS tube is normal.
  3. 3. The spot welder control method of claim 2, wherein the detecting whether the state of the MOS tube is normal comprises: Detecting the D-pole voltage of the MOS tube when the MOS tube G is in an extremely closed state, and judging that the MOS tube is short-circuited and damaged if the D-pole voltage is lower than a set value; And applying a detection pulse with set time to the G pole of the MOS tube, and detecting the voltage response of the G pole to judge whether the G pole is normal or not.
  4. 4. The spot welder control method according to claim 2, wherein the monitoring in real time of the contact resistance of the workpiece to be welded includes: before outputting the spot welding pulse, providing constant current for the spot welding electrode by controlling a constant current power supply on the main board; Measuring the voltage at two ends of the spot welding electrode; The contact resistance is calculated according to ohm's law.
  5. 5. The spot welder control method according to claim 1, comprising: in the spot welding pulse output process, acquiring spot welding current in real time, and calculating energy data output by spot welding based on the integral of the spot welding current and time; After the spot welding pulse is finished, detecting the resistance of the welded workpiece, and obtaining a post-welding resistance value; And comparing the post-welding resistance value with a preset qualification range, and judging whether the welded workpiece is qualified or not by combining spot welding current and/or calculated energy data acquired in the spot welding process.
  6. 6. The spot welder control method of claim 1, wherein the real-time monitoring of the health status of the MOS tube, if the MOS tube is detected to be damaged, immediately turns off the output, comprises: during the spot welding pulse output period, the voltage of the G pole of the MOS tube is compared with the reference voltage in real time through a comparator; When the voltage of the G pole of any parallel MOS tube is lower than the reference voltage, the comparator outputs a signal to control the output of all MOS tubes to be turned off.
  7. 7. The spot welder control method according to any one of claims 1 to 6, comprising: Receiving parameter setting and spot welding instructions issued by an upper computer through a serial port or a 485 interface; uploading state data, collected real-time parameters and post-welding qualified judging results to an upper computer in real time.
  8. 8. A spot welder control circuit, comprising: spot welding the capacitor, and forming a multi-string multi-parallel connection mode through the electrode plates; The control main board is arranged on the electrode plate and is provided with a singlechip, an amplifying circuit and an isolating circuit; The positive electrode of the electrode plate is connected with the positive electrode of the spot welding capacitor, the negative electrode of the electrode plate is connected to the S electrode of the MOS plate, and the negative output electrode of the electrode plate is connected to the D electrode of the MOS plate; MOS plate, install on electrode plate; the positive electrode of the spot welding electrode is connected to the positive electrode of the electrode plate, and the negative electrode of the spot welding electrode is connected to the negative output electrode of the electrode plate; the control main board is connected to the D pole of the MOS board and the positive pole of the capacitor through an independent detection line; and the output line of the pressure sensor is connected to the control main board, is arranged between the driving execution unit and the positive electrode or the negative electrode of the spot welding electrode, and is used for detecting the contact pressure of the spot welding electrode to the welded workpiece during spot welding.
  9. 9. A spot welder control system comprising the spot welder control circuit of claim 8, further comprising: The first monitoring unit is used for monitoring the contact resistance and/or the spot welding pressure of the welded workpiece in real time; the spot welding pulse unit is used for automatically triggering spot welding pulse output when the contact resistance is reduced to a preset resistance triggering threshold value and/or the spot welding pressure is increased to a preset pressure triggering threshold value; The second monitoring unit is used for monitoring whether the spot welding current exceeds a preset current upper limit in real time in the spot welding process, and if so, overcurrent protection is executed; And the third monitoring unit is used for simultaneously monitoring the health state of the MOS tube in real time, and immediately closing the output if the damage of the MOS tube is detected.
  10. 10. The spot welder control system of claim 9, further comprising: And the driving execution unit is used for driving the positive electrode and the negative electrode of the spot welding electrode to clamp the welded workpiece and comprises an air cylinder, an electric cylinder or a motor.
  11. 11. A spot welder, comprising the spot welder control system of any of claims 9-10, further comprising: The spot welding machine comprises a spot welding machine core, a cylinder, an upper electrode, a lower electrode and a pressure sensor, wherein the spot welding machine core is electrically connected with the upper electrode, the lower electrode and the pressure sensor, the upper electrode is arranged below the cylinder, and the lower electrode is arranged above the pressure sensor.

Description

Spot welding machine, control method, circuit and system Technical Field The invention belongs to the technical field of spot welder control, and relates to an intelligent electronic spot welder, in particular to a spot welder, a control method, a circuit and a system, wherein the intelligent electronic spot welder comprises a spot welder triggering mode, a welding quality judgment and a circuit construction. The real-time resistance and/or pressure test method is mainly used for the real-time resistance and/or pressure test of high-current low-voltage energy storage type spot welding and is used for triggering the welding condition of the workpiece and/or judging the quality of the welded workpiece. Background In the manufacturing industry, there are many places where welding of workpieces of different metals is required. At present, the welding technology in the market is quite mature, and the spot welding technology such as argon arc welding, cold welding, welding rod spot welding, laser welding and spot welding is definite and detail. In the market, laser welding is the most advanced electronic welding technology with the strongest comprehensive capacity, but laser cost is high, if the maintenance threshold of problems is high, the laser welding is relatively large in size and is not suitable for small-sized machines and low-cost solutions, so that the traditional resistance welding still has relatively large market advantages. In the traditional resistance spot welding market, the industrial machine with large current is generally a transformer scheme, the scheme is divided into a high-voltage energy storage variable-voltage type spot welding method and a direct-current type spot welding method, the application of the high-voltage energy storage variable-voltage type spot welding method is mainly used for spot welding of small workpieces, the pulse is only once, the pulse is discharged and needs to be charged again immediately to be carried out on the next pulse, so that the productivity per hour is limited, the direct-current type spot welding machine can continuously output large current without waiting for charging, the energy storage type spot welding machine is mainly used in the market and is high in price despite the fact that the energy storage type spot welding machine is high in welding precision, the influence on a power grid is small, the working efficiency is higher, the influence on a base metal is small, and the single spot welding speed is high, so that the energy storage type spot welding machine is incomparable with the direct-current type spot welding machine. Energy storage spot welding may be a user's preference in the context of pulsed spot welding, regardless of cost. In the field of energy storage spot welders, the spot welder is divided into two kinds of spot welder heads, one is a low-voltage spot welder which is used for handheld power supply of a power source capable of conveniently moving, and the other is a high-voltage side energy storage mode. Because high voltage is dangerous and there is no high voltage type Faraday capacitor, the high voltage side energy storage is basically placed inside the large machine, and the main transformer is needed to change the high voltage into low voltage to release energy when in use. The spot welder on the low-voltage side basically has no large-current application in the market, and the biggest reason is that the cost of the MOS tube is too high (thousands of components are needed for once tube explosion without manual work), and the MOS tube is extremely damaged by the large current. There are schemes using laser welding in the market, but the quality of spot welding cannot be measured by using resistance or current, and only the quality of physical mechanical pulling test can be measured, so that the influence on a workpiece is large due to low speed. There are spot welding methods using conventional resistance welding on the market, and more defects are generated. Because the traditional energy storage mode is limited, the working frequency of the transformer is limited, and because the transformer is a high-voltage control secondary low-voltage output, the detection of current and the detection of resistance cannot be tested, and the judgment of a workpiece cannot be processed. In the spot welding system of the related art, as in the scheme disclosed in patent number CN201010213691.5, although pressure and current are attempted to be measured, the pressure detection is indirectly obtained by adopting a grating ranging mode, a coil is required to be additionally arranged for current detection, and the system integration level is low and the arrangement is complicated. Although the scheme disclosed in CN201620770979.5 mentions fast acquisition, its conversion module is external, which increases the complexity and cost of the system. Most of the existing systems can not realize real-time accurate measurement of the spot welding resist