The Way of Searching for Reference Point of CNC Machine Tool

First, the process of returning a reference point to a CNC machine tool:

When returning to the reference point of the numerically-controlled machine tool, the absolute pulse coder method and the incremental pulse coder method are used according to the difference of the detection elements, and the absolute pulse coder is used as a feedback element system. After the machine tool is installed and debugged, during normal use, As long as the backup battery of the absolute pulse encoder is valid, it is not necessary to perform the reference point return every time the power is turned on.

Which method or how to move, the system is determined by the PLC programming and CNC machine parameter settings, the axis speed is also set in the machine parameters, CNC machine tool reference point is the process of PLC system In conjunction with the numerical control system, the zero return command is given by the numerical control system, and then the axis moves in the predetermined direction, and after pressing to the zero point switch (or leaving the zero point switch), the PLC sends a deceleration signal to the numerical control system, and the numerical control system decelerates the movement in the predetermined direction. The zero point pulse is received by the measurement system. After receiving the first pulse, the coordinate value is designed. After all the axes have found the reference point, the process of returning to the reference point ends.

Second, the CNC machine tool to find the reference point:

In a system using an incremental pulse encoder, the machine tool must first perform a reference point return after each power-on to determine the coordinate origin of the machine tool. The search reference point is mainly related to the zero-point switch, encoder, or zero-point pulse of the scale. There are generally two ways.

1) Rapid movement in the direction of the axial predetermined point, the deceleration forward movement continues after the block depresses the zero point switch, until the block disengages the zero point switch, the CNC system begins to search for zero point, when the first zero pulse is received, it is determined Reference point location. Machines equipped with the FANUC system and the Beijing KND system currently use such a zero return method.

2) The axis rapidly moves in the predetermined direction. After the block presses the zero point switch, it reverses the deceleration movement. When it deviates from the zero point switch again, the axis changes direction and moves toward the reference point. When the block presses the zero point switch again, The CNC starts to search for zeros. When the first zero pulse is received, the position of the reference point is determined. Machines equipped with SIEMENS, American AB systems, and Central China systems generally use this zero return method.