How to adjust the backlash of a CNC machine?

First of all, it is confirmed that it is a CNC machine with a semi-closed-loop system, because the full closed-loop does not need to compensate for the backlash, and the open-loop cannot be compensated.

1.Mechanical adjustment, adjust the ball screw nut pair, and tighten it. (not too tight) 2The backlash value of each position of the machine tool is detected by the laser interferometer and input to the internal parameters of the machine tool for compensation (the specific parameters are queried for the machine tool data).

What is called backlash.

Because of the lead screw. There must be a certain gap between the screw and the screw mother, so when it is transformed into a reverse rotation after the forward rotation, within a certain angle, although the lead screw rotates, the screw mother can only drive the workbench to move after the gap is eliminated (on the stressed side), and this gap is the reverse gap, but it should be reflected in the rotation angle of the lead screw.

Taking the Siemens 802CBL system as an example, the detection method of backlash is to fix the standard dial gauge on the tool holder, so that the probe of the gauge touches a fixed object. Use the 10th gear of the hand pulse to advance at a speed of each block to eliminate gaps in this direction.

Then shake the handbar in the opposite direction and record the number of grids that the hand pulse moves in the opposite direction until the dial gauge hand starts to move in the opposite direction, and the number of grids recorded in the reverse rotation of the hand pulse is the reverse gap.

Enter the password in the numerical control system, find the axis data 32450, and enter the measured backlash value into the column of data 32450. You can perform the data effect operation. If the backlash cannot be ruled out after one operation, or it is overfilled.

You must re-enter the new backlash data.

It should be noted that the measurement and effect of the backlash are based on the reference point of the machine tool.

Gap Compensation Method:

1. The feedforward control method is used to improve the response speed of the servo hail system, and the gap compensation value can be reproduced to the output end of the servo system without delay and difference, so as to ensure the rapid compensation of the transmission gap and improve the response speed of the machine tool.

2. The gap compensation method applies the position compensation and the speed compensation at the same time, which improves the gap compensation speed and ensures that the gap compensation value is completely equal to the actual value, improves the accuracy of the CNC polishing machine, and ensures the polishing quality of the blade.

3. Using the feedforward control method, the designed servo motor gap compensation motion process can be directly used as the gap compensation value, and the compensation value can be obtained by only simple calculation, and the compensation value is simple in form and easy to apply.

4. In the process of designing the feedforward control function, there is no specific system, and the velocity feedforward control function can be reduced to a simple combination of typical links.

First of all, you need to find out the reason and see if your machine is taking too long. If so, find someone to fix it. I am a light machine, for the back clearance is not very agreeable, if the lock nut is loose, you don't go to repair the screw and bearings are you to pay for it.

This can be compensated by modifying the parameters.

CNC lathe reverse clearance refers to the transmission clearance of the ball screw pair, including the clearance between the ball screw and the rolling nut and between the ball screw and the bearing that supports it, mainly the axial clearance.

There are many reasons, such as the gap between the motor shaft and the gear shaft due to the keying, the clearance of the gear pair, the clearance between the gear and the lead screw caused by the key connection, the gap caused by the key connection in the coupling, the gap of the lead screw nut, etc., it will cause the initial stage of the reverse movement of the supporting plate to produce an idle stroke, that is, the screw rod rotates but the supporting plate does not move until the gap is eliminated.

Inspection method: manually move the coordinate axis in one direction for a distance and then hit the pallet with a dial gauge, and then move the pallet in the opposite direction with the handwheel until the dial hand swings, and the size of the handwheel movement is the reverse clearance. This value can be entered into the gap compensation in the NC parameters.

The mechanical clearance error of CNC machine tools refers to the comprehensive error caused by the mechanical clearance from the head of the machine tool motion chain to the executor. For example, the feed chain of the machine tool, the error is the gap between the motor shaft and the gear shaft due to the keying, the gap between the gear pair, the gap between the gear and the lead screw caused by the key connection, the gap caused by the key connection in the coupling, the screw nut gap, etc., these errors do not exist when moving in one direction.

The backlash error of the machine tool refers to the error between the motion of the executor and the theoretical value (programming value) when the machine tool actuator changes from forward motion to reverse motion in the process of movement due to the existence of mechanical clearance in the transmission chain of the machine tool, and finally reflects the error of the machining accuracy superimposed on the workpiece. When the CNC machine tool workbench is reversed in its direction of motion, the servo motor will be idled and the workbench will not actually move due to the existence of reverse clearance, which is called loss. For example, in the G01 cutting movement, the reverse deviation will affect the accuracy of the interpolation motion, and if the deviation is too large, it will cause the situation of "the circle is not round enough, and the square is not square enough"; However, in the GOO fast positioning movement, the reverse deviation affects the positioning accuracy of the machine tool, which reduces the position accuracy between the holes during drilling, boring and other hole processing.

If the value of such a backlash is small and has little impact on the machining accuracy, no measures need to be taken; If the value is large, the stability of the system will be significantly reduced, and the machining accuracy will be significantly reduced, especially the curve machining, which will affect the dimensional tolerance and the consistency of the curve, and the backlash must be measured and compensated. Especially the use of semi-closed-loop control of CNC machine tools, the backlash will affect the positioning accuracy and repeated positioning accuracy, which requires us to pay attention to and study the factors of the backlash, the impact and the compensation function when using CNC machine tools, and carefully summarize and find some regular errors in the process of automatic backlash compensation in learning and practice, and take appropriate processing measures to improve the machining accuracy of parts.

Is it necessary to be so cumbersome? Backlash is your X or Z axis, run in one direction for example, 1, and then run 1 in the opposite direction, you will find that the distance you run in the opposite direction is not 1, only, then that's backlash.

First of all, confirm that it is a CNC machine tool with a semi-closed-loop system, because the full closed-loop does not need to compensate for the backlash, and the open section of the leakage ring cannot be compensated.

1.Mechanical adjustment, adjust the ball screw nut pair, and tighten it. (not too tight) 2The reverse clearance value of the first correct position of the machine tool is detected by the laser interferometer instrument, and the internal parameters of the machine tool are input to compensate (the specific parameters are queried for the machine tool data).

What is called backlash.

Because there must be a certain gap between the lead screw and the screw mother, when it is transformed into a reverse rotation after the forward rotation, at a certain angle, although the screw rotates, the screw mother can only drive the worktable to move after the gap is eliminated (on the stressed side), and this gap is the reverse clearance, but it should be reflected in the rotation angle of the lead screw.