In the field of mechanical parts processing industry, there is a concept of machining accuracy, which should be understood by everyone. So today I would like to share with you the technological measures to improve the processing accuracy!
Reduce the original error
This method is a basic method widely used in production. It is to eliminate or reduce these factors after finding out the main factors that cause processing errors. For example, for the turning of slender shafts, the reverse turning method with large tool path is now adopted, which basically eliminates the bending deformation caused by the axial cutting force. If the spring center is supplemented, the influence of thermal elongation caused by thermal deformation can be further eliminated.
2. Compensate the original error
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 is taken as a positive value, otherwise, it is taken as a negative value, and the two values should be equal as far as possible; Or use one original error to offset another, which is also to make the two equal in size and opposite in direction, so as to reduce the processing error and improve the processing accuracy.
3. Transfer original error
In essence, the error transfer method is to transfer the geometric error, stress deformation and thermal deformation of the process system. There are many examples of error transfer method. For example, when the accuracy of the machine tool fails to meet the requirements for parts processing, it is often not to improve the accuracy of the machine tool blindly, but to find ways to create conditions from the process or fixture, so that the geometric error of the machine tool can be transferred to the aspect that does not affect the processing accuracy. For example, grinding the spindle taper hole to ensure its coaxiality with the journal is not guaranteed by the rotary accuracy of the machine tool spindle, but by the fixture. When the machine tool spindle is floating connected with the workpiece, the original error of the machine tool spindle is transferred.
4. Average original error
In processing, the existence of the error of the blank or the previous process (hereinafter referred to as "original error") often causes the processing error of this process, or the change of the material properties of the workpiece, or the change of the process of the previous process (such as canceling the original cutting process after the blank is refined), which causes a large change of the original error. The change of the original error has two main effects on this process:
⑴. Error re mapping, causing error in this process;
⑵. The positioning error expands, causing the error of this process.
The best way to solve this problem is to adjust the average error in groups. The essence of this method is to divide the original error into n groups according to its size, reduce the range of each group of blank error to 1/n of the original, and then adjust the processing according to each group.
5. Average original error
The grinding process is often used for shafts and holes requiring high fitting accuracy. The lapping tool itself is not required to have high precision, but it can perform micro cutting on the workpiece in the process of relative movement with the workpiece, and the high points are gradually worn off (of course, the mold is also partially worn off by the workpiece), which finally makes the workpiece reach high precision. The process of friction and wear between these surfaces is the process of decreasing errors. This is the error averaging method. Its essence is to use closely related surfaces to compare with each other, check each other to find differences from the comparison, and then conduct mutual correction or mutual benchmark processing, so that the error of the machined surface of the workpiece is continuously reduced and even. In production, many precision reference parts (such as flat plate, ruler, angle gauge, end tooth indexing plate, etc.) are processed by the error equalization method.
6. On site processing method
Some accuracy problems in processing and assembly involve the interrelationship between parts or components, which is quite complex. If we blindly improve the accuracy of parts and components, sometimes it is not only difficult, or even impossible. If we adopt the local processing method (also known as self processing and repair method), we may easily solve the seemingly difficult accuracy problems. Local machining method is often used as an effective measure to ensure the machining accuracy of mechanical parts.