How to troubleshoot the failure of the lifting electromagnetic chuck

When the lifting electromagnetic chuck is in use, there is no magnetic force, which will cause problems with the equipment, so how to check it? Let me tell you here.

Press the lifting electromagnetic chuck grinding wheel motor button to start the electromagnetic chuck switch. Due to the interlocking connection of the relay, the workpiece cannot be closed and the grinding wheel motor cannot be started.

Open the power distribution box of the machine tool, use a test pen to check the power at the terminal 2 of the fuse, and then use a multimeter to measure the power supply voltage of 500V AC to 380V. Disconnect the main power switch, check whether the AC contactor is mechanically stuck, and remove a contactor coil Wire, use a multimeter to measure the resistance of the 2 ends of the coil, if the needle is normal, it proves that the coil is good.

Connect the wire of the lifting electromagnetic chuck coil, remove the undervoltage relay shell, measure the resistance at the 2nd end of the coil, the needle still indicates normal, indicating that the undervoltage relay coil is not disconnected, and then check whether the relay has a mechanical card. Then turn off the upper power switch and use Use the multimeter AC gear to measure the voltage on the transformer side to be 135V, replace the DC block, and measure the voltage at the 2nd end of the rectifier tube 2. Under normal circumstances, the DC voltage output by the bridge rectifier should be 110V, and there is no voltage output at this time. Disconnect the main power switch ,Measure the 4 rectifier 2-stage tubes with multimeter resistance, and find that 2 of them have problems. Solder the wires connecting the 2-stage tubes, remove the 2-stage tubes, measure and check again to prove that the tubes are damaged. Replace 2 new ones 2 tubes, connect the wires, and check whether the welding is firm.

Turn off the main power switch, use the DC gear of the multimeter to measure the 2nd end of the rectifier 2-stage tube, the voltage indication, the voltage value is 110V. The operator presses the button of the grinding wheel motor, starts the lifting electromagnetic chuck switch, the workpiece can be attracted, and the fault has been resolved.