Calibration of LPG cylinder spot welding machine requires the establishment of standardized processes in terms of mechanical accuracy, electrical parameters and process verification to ensure batch welding consistency. The specific steps are as follows:
1. Mechanical system calibration
Electrode alignment: Use a laser alignment instrument to detect the coaxiality of the upper and lower electrodes. The deviation must be ≤0.1mm, otherwise it will cause the weld point to shift or uneven pressure. For example, by adjusting the electrode arm slider (accuracy 0.01mm level), the center of the electrode head coincides with the position of the cylinder to be welded, and use a feeler gauge to detect the parallelism of the electrode and the workpiece (gap ≤0.05mm).
Pressure calibration: Use a pressure sensor (range 0-10MPa, accuracy ±1%) to monitor the electrode pressure in real time. The standard pressure is 0.3-0.5MPa when welding 3mm carbon steel. If the pressure fluctuation exceeds ±5%, check the cylinder sealing or servo motor encoder (resolution 1000 lines) to avoid pressure attenuation due to mechanical wear.
2. Electrical parameter calibration
Current and time calibration: Use an oscilloscope (bandwidth ≥ 100MHz) to collect the welding current waveform. The peak current error of the energy storage welding machine should be ≤ ± 3% (for example, when the setting is 80kA, the actual measurement range is 77.6-82.4kA), and the inverter type needs to control the current rise rate to ≤ 5kA / cycle. The welding time is calibrated by a high-frequency counter (accuracy 0.1ms). For example, when welding at 20 cycles (0.4s), the error must be ≤ 0.5 cycles.
Energy consistency: The energy storage type needs to test the capacitor capacity regularly (using an LCR bridge), and replace the capacitor bank when the capacity decay exceeds 15%. The inverter type uses a power analyzer to calibrate the output energy to ensure that the energy fluctuation is ≤±2% for 10 consecutive welding times under the same parameters.
3. Process Validation and Process Control
First piece inspection: 3-5 first pieces are welded before each batch of production, and the process stability is verified by metallographic analysis (weld nugget diameter 5-6mm, weld penetration 60%-70%) and tensile shear test (≥3000N). If the weld nugget size deviation exceeds 10%, the current or pressure parameters need to be readjusted.
Online monitoring: Install an infrared thermal imager (temperature measurement range 0-1000℃, accuracy ±2%) to monitor the temperature field of the solder joint in real time, set the temperature threshold (such as the peak temperature of the carbon steel solder joint is 1400±50℃), and automatically alarm and stop the machine for calibration when it exceeds the range. At the same time, the welding controller records the current, pressure, and time data of each solder joint to form an SPC control chart. When the CPK value is less than 1.33, the calibration process is triggered.
Periodic calibration plan: The mechanical part is calibrated once a week, and the electrical parameters are calibrated once a month. Combined with the first-piece verification when the cylinder batch is replaced, the consistency of the welds can be controlled within ±5%, meeting the mass production requirements of LPG cylinders.
If you want to learn how to calibrate the LPG Cylinder Spot Welding Machine to ensure batch-to-batch welding consistency
, you can contact Qineng Welding System, we will do our best to help you !
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