Dalian Haisen Machinery Co.,Ltd

The Stopping Fault Treatment Of CNC Vertical Lathe

Jan 28, 2019

     The spindle of a CNC vertical lathe is perpendicular to the horizontal plane.This kind of machine tool is mainly used for processing large and complex parts with large radial dimension and relatively small axial dimension.

      Parking fault phenomenon of CNC vertical lathe:

      CNC vertical lathe in the parking when a loud noise, while the workshop power trip.Firstly, check the electrician in the workshop to check the power supply system. The automatic air circuit breaker tripping is located in the humid environment. The connecting rod mechanism of automatic tripping in the switch box has been corroded.Secondly, the workshop power transformer capacity is small, overload operation.Its normal phase voltage is only 340V.Finally, a thyristor of the CNC vertical lathe has been burnt out. When the drive circuit was checked, the trigger pulse was short, only one fourth of the normal trigger pulse amplitude, which was further verified to be caused by the poor performance of the amplifier tube in the trigger circuit.

      Fault analysis:

      The results of phase - missing in rectifier and inverter are different.In the rectifying state, the thyristor with always high trigger potential is turned off while the former thyristor is subjected to inverse-phase voltage.The inverse-phase blocking state is the main state during the turn-off of thyristor.Even if the latter thyristor does not trigger, the thyristor will automatically shut off due to zero crossing at a certain time.However, if it is in the case of stopping and slowing down, that is, in the case of inverter, the thyristor with high trigger potential is also on, and the former thyristor is under reverse pressure and shut off, then the thyristor is in the state of forward blocking for a long time when it is shut off.

      In this way, if the latter thyristor does not conduct, the thyristor will continue to conduct for another cycle and enter the positive half cycle due to the discharge of inductance, and the thyristor will continue to conduct and hinder the thyristor conducting at the same time.As a result, the positive voltage output by the thyristor and the electric potential of the motor superposition to produce a large current, which then produces inverter subversion, the light is burned out fuse, the heavy is burned out thyristor.If the CNC vertical lathe workshop voltage supply system is normal, no big fluctuations, may not burn out the thyristor.The fault is caused by the large voltage fluctuation of the ac power grid, the small transformer capacity in the workshop, the overload operation, the small trigger pulse amplitude of the b-phase positive group, and the damage of the main switch box of the power supply system in the workshop.

      Treatment: replace the automatic air circuit breaker;Replace the thyristor with a new one.