Tag Archive Computer gong processing to prevent accuracy error

Computer gong processing to prevent accuracy error

It is impossible to make the machining exactly the same as the ideal part, and there will always be different deviations. The deviation degree of the actual geometric parameters after machining from the ideal geometric parameters is called machining error. These machining errors often appear in “large machining process”,

The details are as follows:

Processing economic precision

Because there are many factors affecting the machining accuracy in the machining process, the same machining method can achieve different accuracy under different working conditions. The processing error delta is inversely proportional to the processing cost C. The processing economic precision of a certain processing method should not be understood as a certain value, but as a range, which can be said to be economic.

Original error

There are all kinds of errors in the machining process system composed of machine tool, fixture, cutter and workpiece. These errors will be reflected as the machining errors of workpiece in different ways (or expanding or shrinking) under different working conditions.

The original errors of process system mainly include geometric error, positioning error, processing error caused by force deformation, processing error caused by heat deformation, deformation caused by redistribution of internal stress, principle error, adjustment error, measurement error, etc.

2、 Set error of process system

  1. Geometric error of machine tool

In machining, the forming movement of the tool relative to the workpiece is generally completed by the machine tool. Therefore, the machining accuracy of the workpiece depends on the accuracy of the machine tool to a great extent. The manufacturing errors of machine tools have great influence on the machining accuracy of workpieces: spindle rotation error, guide rail error and transmission chain error. The wear and tear of the machine tool will reduce the working accuracy of the machine tool.

Spindle rotation error

The spindle of machine tool is the datum for clamping the workpiece or cutter, and transmits the motion and power to the workpiece or cutter. The rotation error of spindle will directly affect the accuracy of the workpiece to be processed.

The spindle rotation error refers to the variation of the actual rotation axis of the spindle at each instant relative to its average rotation axis. It can be divided into three basic forms: radial circular runout, axial movement and angular swing.

The main reasons for the radial rotation error of the spindle are: the coaxiality error of several sections of the Journal of the spindle, various errors of the bearing itself, coaxiality error between the bearings, spindle winding, etc. But their influence on the radial rotation accuracy of the spindle varies with different machining methods.

The main reason for the axial movement is the verticality error between the end face of the spindle shoulder and the bearing end face of the spindle rotation axis.

In the process of large-scale machining, the machining error caused by spindle rotation error is different with different machining methods. When machining outer circle and inner hole on lathe, the radial rotation error of spindle can cause roundness and cylindricity error of workpiece, but it has no direct effect on the end face of workpiece. The axial rotation error of CNC machining spindle has little influence on machining outer circle and inner hole, but has great influence on the perpendicularity and flatness of machined end face. When turning the thread, the spindle rotation error can make the lead of the processed thread produce periodic error.