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Analysis of Grinding Quality Error of CNC Grinding Machine

The grinding process consists of a grinding machine, a fixture, a grinding wheel, and a workpiece. The grinding accuracy depends on the accuracy of the whole grinding process system, and the grinding quality is mainly affected by the principle error, grinding machine error, grinding wheel error, fixture error and other factors.

1. Principle error

The principle error is due to the use of approximate machining motion or approximate grinding wheel profile two. When grinding teeth by the generation method, there should be accurate generation motion between the workpiece and the grinding wheel, but the actual tooth profile obtained is an approximate involute composed of many short segments, thus causing the principle error.

2. CNC internal grinder error

The error caused by the manufacturing accuracy of the internal grinding machine is called the grinding machine error, in which the geometric accuracy of the grinding machine, such as the spindle rotation accuracy, the height of the head frame, the tailstock and the grinding wheel frame, and the guide rail error, is the impact on the processing.

3. Internal grinding wheel error

The grinding wheel error includes the correction error of the grinding wheel and the error caused by the grinding wheel wear. Because the contour error of the grinding wheel will cause the error of the corresponding size and shape of the workpiece, the grinding wheel needs fine dressing and has a certain durability.

4. Internal grinder fixture error

Fixture manufacturing error, positioning error and wear in the course of use, will be the first workpiece machining accuracy.

5. Error caused by thermal deformation of process system

The process system is affected by grinding heat, friction heat and sunlight radiation, and conducts heat conduction. For example, CNC grinding machine, grinding machine spindle components, bed guide rail thermal deformation will cause changes in the relative position of the components, thus affecting the machining accuracy. The deformation of the workpiece is mainly caused by grinding heat.

6. Force deformation of process system

The process system is an elastic system. Under the action of grinding force, gravity, and inertial force, the components of the system will cause elastic deformation, such as the bending deformation of the workpiece when grinding the Xichang shaft. At the same time, the components in the system will also be displaced due to the gap or deformation of their contact. The way to reduce the acceptance deformation is to reduce the external force and improve the rigidity of each part of the process system.

7. The deformation of the internal stress hidden in the workpiece of the internal grinding machine.

In the process of cutting and heat treatment, due to uneven cooling shrinkage, uneven plastic deformation or changes in metal tissue, internal stress will be generated in the workpiece, and the workpiece with internal stress will deform during processing.

8. Measurement error

The measurement error includes two parts: the manufacturing error of the measuring tool itself and the error of the measurement method. The inspection of the accuracy of the workpiece is realized by the method of measurement, so special attention is paid to improving the accuracy of measurement in processing.

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