Methods to ensure and improve machining accuracy can be summarized as follows:
1. Reduce the original error
To improve the geometric accuracy of machine tools used in parts processing, to improve the accuracy of fixtures, measuring tools and tools themselves, and to control the force of the process system, deformation caused by heat, tool wear, deformation caused by internal stress, measurement error and so on are directly to reduce the original error. In order to improve the machining precision, it is necessary to analyze the original errors that produce machining errors, and take different measures to solve the main original errors according to different situations. For the processing of precision parts, the geometric accuracy, stiffness and thermal deformation of precision machine tools should be improved as much as possible. The machining of parts with forming surface is mainly about how to reduce the shape error and installation error of forming tool.
This method is a basic method widely used in production. It is an attempt to eliminate or reduce the main factors that cause machining errors after they have been identified.
2. Compensate for the original error
The error compensation method is to artificially create a new error to offset the original error in the original process system. When the original error is negative, the artificial error should be positive; otherwise, the error should be negative, and the size of the two should be equal as far as possible. Or use one kind of original error to offset another kind of original error, but also try to make the size of the two equal, opposite direction, so as to reduce the processing error, improve the purpose of machining accuracy.
3. Transfer the original error
The error transfer method is essentially the geometric error, stress deformation and thermal deformation of the process system. There are many examples of error transfer method. Such as when the accuracy of the machine tool can not meet the processing requirements of parts, often not blindly improve the accuracy of the machine tool, but from the process or fixture to find ways to create conditions, so that the geometric error of the machine tool is transferred to the aspects that do not affect the processing accuracy.
4. Divide the original error evenly
In the process, because of the blank or the existence of the process error, often cause the process error of this process, or because of the workpiece material performance change, or the process change of the last process (such as blank finishing, the original cutting processing process is cancelled), cause the original error to produce a larger change. To solve this problem, the method of grouping and adjusting the equalization error is adopted. The essence of this method is to divide the original error into N groups according to its size, each group of blank error range is reduced to the original 1/ N, and then adjust processing according to each group.
5. Homogenize the original error
The grinding process is often used for shafts and holes requiring high mating accuracy. Grinding tool itself does not require a high precision, but it can do in the process of relative movement and workpiece workpiece for micro cutting, the high point is gradually worn off (of course, the mold is also part of the workpiece grinding), so that the workpiece to achieve high accuracy. This process of friction and wear between surfaces is a process of error reduction, which is called error homogenization.
6. Local processing method
Precision in machining and assembly, and some problems involved in the relationship between the parts or components, and is quite complex, if blindly raise precision parts themselves, sometimes not only difficult, even impossible, if the on-site processing method (also known as its processing and replacement method), could easily to solve the problem of the accuracy of the looks very difficult. Local machining method is often used as an effective measure to ensure machining accuracy of mechanical parts.