Measures to improve the machining accuracy of mechanical parts

In the field of mechanical parts processing, there is a concept of machining accuracy that everyone should be familiar with. So today, let me share with you the process measures to improve machining accuracy!

1. Reduce original errors

This method is a fundamental approach widely used in production. It aims to eliminate or reduce the main factors that cause machining errors after identifying them. For example, the turning of slender shafts now adopts the large tool reverse turning method, which basically eliminates the bending deformation caused by axial cutting forces. If supplemented with springs, the effect of thermal elongation caused by thermal deformation can be further eliminated.

2. Compensate for 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 takes a positive value. Conversely, when the original error is negative, a negative value is taken, and the two values are made as equal as possible; Alternatively, one type of original error can be used to offset another type of original error, aiming to make the two equal in size and opposite in direction, in order to reduce machining errors and improve machining accuracy.

3. Transfer the original error

The error transfer method essentially transfers geometric errors, stress deformations, and thermal deformations of the process system. There are many examples of error transfer method. When the precision of the machine tool cannot meet the requirements of part processing, it is often not just about improving the precision of the machine tool, but about finding ways from the process or fixture to create conditions that transfer the geometric errors of the machine tool to aspects that do not affect the machining accuracy. To ensure the coaxiality between the spindle taper hole and the journal during grinding, it is not guaranteed by the rotational accuracy of the machine tool spindle, but by the fixture. After the floating connection between the machine tool spindle and the workpiece, the original error of the machine tool spindle is transferred.

4. Divide the original error equally

In processing, due to errors in the blank or previous process (hereinafter collectively referred to as“ Original error; ）The existence of errors often leads to machining errors in this process, or due to changes in the material properties of the workpiece, or changes in the process of the previous process (such as canceling the original cutting process after refining the blank), causing significant changes in the original error. This change in original error has two main impacts on this process:

⑴. Error reflection, causing errors in this process;

⑵. The expansion of positioning error causes errors in this process.

To solve this problem, the method of grouping and adjusting the average error is adopted. The essence of this method is to divide the original error into n groups according to their size, and reduce the error range of each group's blank to 1/n of the original, and then adjust the processing according to each group separately.

5. Normalize the original error

Grinding technology is often used for shafts and holes that require high fitting accuracy. The research tool itself does not require high precision, but it can perform micro cutting on the workpiece during relative motion, gradually grinding off the high points (of course, the mold is also partially ground off by the workpiece) to achieve high precision on the workpiece. The process of friction and wear between surfaces is a process of continuously reducing errors. This is the error equalization 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 perform mutual correction or benchmark processing, so that the errors of the workpiece's machined surface are continuously reduced and equalized. In production, many reference parts (such as flat plates, rulers, angle gauges, end tooth indexing discs, etc.) are processed using the error equalization method.

6. On site processing method

In processing and assembly, there are some precision issues that involve the interrelationships between parts or components, which are quite complex. If we blindly improve the precision of the parts or components themselves, sometimes it is not only difficult, but also impossible. If we adopt the on-site processing method (also known as self processing repair method), it may be very convenient to solve seemingly difficult precision problems. In situ machining method is often used as an effective measure to ensure the machining accuracy of mechanical parts.

• Previous:What is the mechanical processing technology related to shaft parts?
• Next:No more!