Today, the precision machining manufacturer wants to briefly introduce the technology and steps of precision machining. The administrator, of course, does not know the situation very well, so I asked the company's technical staff to understand.
The technicians of German Control Precision Machinery told us that the precision machining process is generally formulated in accordance with the machining process regulations, which can be roughly divided into two steps. The first is to draw up the process route for precision parts processing.
To put it bluntly, it is to analyze the parts that need to be processed first. If there is no physical object, you can analyze the drawings of the parts. Then, according to the analyzed and prepared report, the process size of each process, the equipment and process equipment used, the cutting specifications, and the working hours quota are determined.
The formulation of the process route is to formulate the overall layout of the process, whether a part is processed well or not, the main task is to select the processing method of each surface, determine the processing sequence of each surface, and the number of processes in the entire process. This step is very important, you only have to do all the preparations well, and then the following things will be easy to handle.
The general principle of drawing up the process route (this step is generally done by the design engineer)
- 1. Process the datum surface first. In the process of parts processing, the surface as the positioning reference should be processed first, and the general part shape should be processed according to the drawings or the parameters analyzed before. In order to provide a precise benchmark for the subsequent processing as soon as possible. Called "benchmark first."
- 2. Divide the processing stages. The surface of precision parts with high processing quality requirements is divided into processing stages, which is very important and complicated. Generally, it can be divided into three stages: rough machining, semi-finishing and finishing. The main purpose is to ensure the processing quality; facilitate the rational use of equipment; facilitate the arrangement of the heat treatment process; and facilitate the discovery of blank defects.
- 3. Face before hole. For parts such as boxes, shafts, and connecting rods, the plane should be processed first and then the holes should be processed. In this way, the holes can be positioned on the plane to ensure the accuracy of the plane and the position of the hole, and the processing of the holes on the plane is convenient. Because the processing plane is relatively simple and the hole is more complicated, it is more reasonable to do the short answer first and then do the complicated one.
- 4. Finishing processing. Finished workpiece. This is the last step and it is also very important. The finish processing of the main surface (such as grinding, honing, finishing, rolling, etc.) should be carried out at the last stage of the process route. The surface finish after processing must meet the customer's requirements, and the processing must be ensured Place the precision parts that come out, strive to be handled with care, because slight collisions will damage the surface. In Japan, Germany and other countries, after finishing processing, they must be protected with flannel. Never use hands or other The object directly touches the workpiece to avoid damage to the finished surface due to transfer and installation between processes. After all, they are precision parts, so the requirements for parts are relatively high, and a little superficial error will affect the use of parts.
The above is the general situation of processing arrangement. Of course, there are some special cases, and some specific cases can be handled according to the following principles.
- (1) In order to ensure the accuracy of parts processed. Rough machining and finishing are best performed separately. Because of the large amount of cutting during rough machining, the workpiece is subjected to large cutting force, clamping force, heat generation, and the machined surface has a significant work hardening phenomenon, there is a large internal stress inside the workpiece, if rough machining and fine If the processing continues, the precision of the finished parts will be quickly lost due to the redistribution of stress. For some parts that require high machining accuracy. After rough machining and before finishing, low temperature annealing or aging treatment procedures should also be arranged to eliminate internal stress. This is very important. If you have the conditions, you should separate the finishing and roughing as much as possible. You should know that if you save time, you may bring a large part of the parts that are unqualified, and the loss is greater. Of course, this is also based on It depends on different circumstances.
- (2) Reasonably select precision parts processing equipment. Rough machining mainly cuts off most of the machining allowance, and does not require high machining accuracy. Therefore, rough machining should be performed on a machine with greater power and less precision. The finishing process requires higher precision machining. Rough and fine machining are processed on different machine tools, which can not only give full play to the equipment capabilities, but also extend the service life of precision machine tools. In this regard, Xin Gongyi Company has done very well, purchasing machine tools imported from Japan for precision processing.
- (3) In the machining process route, there are often heat treatment processes. The location of the heat treatment process is arranged as follows: In order to improve the cutting performance of the metal, such as annealing, normalizing, quenching and tempering, etc., it is generally arranged before mechanical processing. In order to eliminate internal stress, such as aging treatment, quenching and tempering treatment, 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., it is generally arranged after machining. If there is a large deformation after heat treatment, the final processing procedure must be arranged.