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Share the precision machining process and steps

Author: Shenzhen Jin Haixing Electrical Co., Ltdissuing time:2018-03-09 09:50:54view:119SML

Precision machining processes generally follow the formulation of mechanical processing procedures and can be roughly divided into two steps. The first is to formulate the process route for precisi...
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Precision machining processes generally follow the formulation of mechanical processing procedures and can be roughly divided into two steps. The first is to formulate the process route for precision parts processing. To put it plainly, it is to analyze the parts that need to be processed first. If there is no physical part, you can analyze the drawings of parts and components. Then, based on the analysis and the drafted report, the process dimensions, equipment and process equipment used for each process, cutting specifications and man-hour quotas are determined.


The picture shows Kingship CNC machining area

The drafting of the process route is to formulate the overall layout of the process. The processing of a component is good or bad. The main task is to select the processing methods for each surface, determine the processing sequence of each surface, and the number of processes in the entire process. This step is critical. You can only do everything in your preparation. The following things will be easier to handle.

Formulate the general principles of the process route (this step is usually done by the design engineer)

1. First machine the datum plane.
During the processing of the part, the surface that serves as the reference for the positioning should be machined first, and the general shape of the part should be machined out based on the drawings or the previously analyzed parameters. In order to provide a refined reference for the processing of subsequent processes as soon as possible. Called "benchmark first."

2. Divide the processing stage. The surface of high-precision components requiring high processing quality is divided into processing stages. This is very important and complicated. Generally can be divided into rough machining, semi-finishing and finishing three stages. It is mainly to ensure the quality of processing; it is conducive to the rational use of equipment; it is convenient for arranging heat treatment processes; and it is convenient to find rough defects.

3. First back hole. For the box, shaft and connecting rod and other parts should be processed after the first plane processing hole. In this way, the machined holes can be positioned in a plane to ensure the accuracy of the position of the plane and the holes, and the processing of the holes in the plane can be facilitated. Because the machining plane is relatively simple, and the holes are more complicated, the first thing to answer is done, and it is more reasonable to do complex things.

4. Finishing. Finished workpieces. This is the last step and it is also very important. The finishing of major surfaces (such as grinding, honing, grinding, rolling, etc.) shall be carried out in the final stage of the process route. The surface finish after processing must meet the requirements of the customer and must be ensured. The precision components that are processed are placed in a position where they can be handled lightly, because minor collisions can damage the surface. In countries such as Japan and Germany, they must be protected by flannel after finishing, absolutely not allowed by hand or Other objects are in direct contact with the workpiece so that the finished surface is not damaged due to transfer and installation between processes. After all, it is a precision component, so the requirements of the parts are relatively high, and there is a little wrong surface, which will affect the use of the parts.

The above is the general case of processing procedures. Of course, there are some special circumstances. Some specific situations can be dealt with according to the following principles.

(1) In order to ensure the accuracy of the parts processed. Roughing and finishing are best done separately. Due to the large amount of cutting during rough machining, the cutting force and clamping force of the workpiece are large, the amount of heat generation is large, and the machining surface has more remarkable work hardening phenomenon. There is a large internal stress inside the workpiece, if rough machining and fine If the machining is carried out continuously, the accuracy of the finished part will be quickly lost due to the redistribution of stress. For parts that require high machining accuracy. After roughing and prior to finishing, low-temperature annealing or aging treatments should also be arranged to eliminate internal stresses. This point is very important, conditional, and try to separate the finishing from the roughing. You must know that if you plan to save time, you may bring in a large part of the parts that are unqualified and lose more. Of course, this is based on It depends on different circumstances.

(2) Reasonably select precision parts processing equipment. Roughing mainly cuts away most of the machining allowance, and does not require high machining accuracy. Therefore, rough machining should be performed on a machine tool with high power and low accuracy. The finishing process requires the use of higher precision machining. Coarse and fine machining are processed on different machine tools, which not only gives full play to equipment capabilities, but also extends the service life of precision machine tools.

(3) In the mechanical processing route, there are often heat treatment steps. The location of the heat treatment process is arranged as follows: In order to improve the metal cutting performance, such as annealing, normalizing, tempering, etc., are generally arranged before machining. In order to eliminate internal stress, such as aging treatment, quenching and tempering, etc., it is generally arranged after rough machining and before finishing. In order to improve the mechanical properties of parts, such as carburizing, quenching, tempering, etc., are generally arranged after machining. If there is a large deformation after heat treatment, final processing steps must also be arranged.

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