When CNC machining returns to the reference point, the absolute pulse encoder is used as the feedback element according to the different types of absolute pulse encoder and incremental pulse encoder. After the machine is installed and debugged, the system is in normal use. As long as the backup battery of the absolute pulse encoder is valid, every time the power is turned on, there is no need to return to the test point.

In the system using incremental pulse encoder, the machine tool must first perform the datum point operation after each start to determine the coordinate source of the machine tool, and find the reference mainly related to the zero pulse of the zero switch, encoder or grating ruler point. There are generally two ways of machining in Shanghai.

The main results are as follows: 1) The block quickly moves in the direction of the predetermined fixed point. The block presses the zero switch, then slows down and continues to move forward until the block is separated from the zero switch, and the CNC system starts to search for the zero point. To determine the position of the reference point during the second zero pulse, perform the following operations. Currently, machine tools equipped with FAN UC system and Beijing KND system generally adopt this zero return method.

2) The axis moves rapidly in the predetermined direction, and the blocking block undergoes reverse deceleration movement after pressing the zero switch. When the switch is separated from the zero point switch, the axis changes and moves toward the reference point. When the block presses the zero point switch again, the CNC system starts to find the zero point. When the first zero point pulse is received, Shanghai Machining can determine the reference point. Point location. Machine tools equipped with Siemens, American AB system and Huazhong system generally adopt this zero-return mode.

The way or how the system moves is determined by the PLC programming and the parameter settings of the CNC system. The machine parameters also set the axis speed. The CNC machining process is completed by the cooperation of the PLC system and the CNC system. The CNC system gives an instruction to return to zero.

Then the axis moves in a predetermined direction. After pressing the zero switch (or leaving the zero switch), the PLC sends the deceleration signal to the numerical control system, and the NC system decelerates according to the predetermined direction. The Shanghai Machining System receives the zero pulse through the measurement system. After receiving the first pulse, design the coordinate value. After all the axes have found the reference point, the process of returning to the reference point ends.