1. The cause of the error
Process processing will be affected by many factors, resulting in certain errors. These factors can be attributed to two categories: one is in the process of metal cutting, and the other is the process structure itself and state. It can be divided into the following categories:
(1) Error caused by spindle rotation
This kind of error is mainly caused by axial movement, angular swing, etc., including various errors of the bearings themselves, and axial errors between bearings.
(2) Guide rail error
The machine tool guide rail is the standard for the relative position of the machine tool and its components, which is also the benchmark for the operation of the machine tool. The error generated by the guide rail will be directly reflected on the workpiece, which will have a certain impact on the machining accuracy of the workpiece. When the tool post moves, it will produce a certain swing, and the movement of the tool tip will form a curve, causing errors in the shape of the workpiece. In addition, the installation quality and uneven wear of the guide rails are also the main factors that produce guide rail errors, and the wear of the guide rails will also reduce the accuracy of the machine tool.
(3) Transmission chain error
This is the movement of the components between the two ends of the transmission chain, and the error produced is mainly judged based on the rotation angle of the end.
(4) Unique errors of CNC machine tools
There are two biggest differences between CNC machine tools and general machine tools: one is that the CNC machine tool is a CNC system; the other is that the drive system of the CNC machine tool is a servo system. However, there are many similarities between the errors generated on CNC machine tools and the errors generated on ordinary machine tools, such as the sampling delay error in the detection system.

2. Methods to eliminate errors
There are three main ways to eliminate errors: ①Automatic control method. Let the technological process system form an automatic processing cycle system, so that the measurement and adjustment can be automatically completed during the technological process; ②Trial cutting method. Through trial cutting, some rules can be found and errors can be eliminated; ③fixed-size tool method. Use a tool with a certain shape and size to meet the shape and size of the processing requirements.

3. Measures to improve the precision of machine tools
There are five measures to improve the precision of the machine tool: ①Reduce the original error. Find out the cause of the error, eliminate and reduce it; ②compensate the original error. Create some errors artificially to offset the original errors; ③Transfer the original errors. Transfer geometric errors and thermal deformations in the process system; ④Equally divide the original errors. Divide the error into several parts, and adjust and process each part; ⑤In-situ processing method. This method can quickly solve the accuracy problem, and can also protect the accuracy of the workpiece.
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