CNC machine tool CNC machining can not return to the reference point problem - Database & Sql Blog Articles

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When CNC machining returns to the reference point, it is divided into absolute pulse encoder mode and incremental pulse encoder mode according to different detection components. The system using absolute pulse encoder as feedback component is used in the normal use process after the machine is installed and debugged. The backup battery of the absolute pulse encoder is valid, and each time the power is turned on, it is no longer necessary to perform the reference point return operation. In a system using an incremental pulse encoder, each time the machine is turned on, it must first perform a reference point return operation to determine the coordinate origin of the machine tool. The reference point is mainly related to the zero point pulse of the zero point switch, the encoder or the scale. There are generally two ways.
1) The axial direction moves at a predetermined point direction. After the stop is pressed, the zero point switch is decelerated and continues to move forward. After the stop is released from the zero point switch, the CNC system starts to look for the zero point. When the first zero point pulse is received, it is determined. Reference point location. Machine tools equipped with the FANUC system and the Beijing KND system currently use this type of zero return.
2) The axis moves quickly in the predetermined direction. After the stop is pressed to the zero switch, the reverse deceleration motion. When it is separated from the zero switch, the axis changes direction and moves to the reference point. When the stop presses the zero switch again, The CNC begins to look for the zero point and determines the reference point position when the first zero pulse is received. Machine tools equipped with SIEMENS, American AB system and Central China system generally adopt this method of zero return.
Which method or how to move, the system is determined by the programming of the plc and the machine parameter setting of the numerical control system. The movement speed of the axis is also set in the machine parameters. The process of machining the CNC back to the reference point is the PLC system. When the CNC system is completed, the CNC system gives the zero return command, then the axis moves in the predetermined direction, and after pressing the zero switch (or off the zero switch), the PLC sends a deceleration signal to the CNC system, and the CNC system decelerates in a predetermined direction. The zero pulse is received by the measurement system, and the coordinate value is designed after the first pulse is received. After all the axes have found the reference point, the process of returning to the reference point ends.
CNC machining can't return the fault of the reference point. There are generally the following situations: First, there is a problem with the zero switch; Second, there is a problem with the encoder; Third, there is a problem with the system measurement board; Fourth, the zero switch and the hard (soft) limit position are too Near; fifth is the loss of system parameters and so on.