I. Machining process of parts
The main content of the part machining process is in the modern society. Generally, the machining of parts is carried out in the way of numerical control. Therefore, when machining parts, it is necessary to first understand the relevant processing technology, develop a suitable processing plan, and deepen the discussion and analysis of the part numerical control processing process. First of all, when machining parts, it is necessary to select a suitable CNC machine tool, operate on the CNC machine tool, and determine what the processing procedure is.
Then, make a suitable machining plan for NC machining of parts, analyze the drawings of the machined parts, process the precision parts and adopt appropriate machining technology. In the machining of parts, the most important thing is to design the processing technology of parts, which is related to the quality of parts. We should clarify the process steps of parts processing, and confirm the selection of benchmarks, processing tools, fixtures, devices, processing strategies and process parameters to formulate the most suitable processing technology. In addition, we should compile and check the NC programming program of part machining, control the programming error, and improve the programming quality and efficiency.
The characteristics of part machining process The machining of parts is generally carried out in the way of numerical control, so it is inevitable to have the characteristics of numerical control processing, and also has its own characteristics.
(1) NC machining of parts requires the content of processing technology to be meticulous and detailed. When NC machining parts, a NC machining plan will be prepared in advance, and then the operation will be carried out on the NC machine tool, including the processing program, the selected tool, the processing method and the corresponding processing parameters. These requirements require a detailed and detailed plan when machining parts. The plan will be analyzed, and finally the processing program of the parts will be formed.
(2) The CNC machining process of parts is required to be strict and accurate. The mechanical processing technology of parts adopts the form of numerical control processing, which makes the precision and quality of parts processing higher, and the processing process does not require too many people, saving manpower. But on the other hand, the reduction of human intervention makes it impossible to manually adjust parts if problems occur in the processing process. Therefore, the level of mechanical numerical control processing technology of parts is set closely and accurately, There should be no small error. Because of the error, it is likely that the processing technology will not meet the specification and the parts will be discarded, resulting in mechanical accidents.
(3) In the process of mechanical NC processing of parts, mathematical calculation shall be carried out for the part graphics and the set value of the programmed size. Because the machining of parts is in the form of numerical control, programming design shall be carried out before machining, the size of parts shall be in geometric form, and the size of parts shall be calculated mathematically. Therefore, optimization design of parts shall be carried out from all aspects during programming.
Second, analysis of the design principles of machining process of parts
The principle for selecting the positioning datum The positioning datum refers to the surface of the relative position of the part to the machine tool and the cutter when the machining of the part is stopped, while the part uses the most original surface that has not been processed during the initial processing. This is the coarse datum. If the positioning datum that has been processed is used after the initial processing, this is the fine datum. Then, when machining parts, what appearance should be selected as the positioning benchmark, which requires caution when machining parts. What kind of positioning datum to choose will affect the quality of parts processing and the complexity of machine tool fixture construction. What are the principles for selecting the coarse and fine benchmarks?
The selection of rough datum shall follow the principle of selecting rough datum. When machining parts, ensure that the materials are sufficient, the machining surface has sufficient allowance, and the size and position of the machined surface of the part that is not machined shall meet the requirements of the machining drawing. If the coarse datum is selected, it is necessary to ensure that the surface of the part is convenient for positioning, clamping and processing, and the selected fixture is as simple as possible.
When selecting the rough base, the machined surface and the non machined surface must be confirmed. There must be accurate location selection. Generally, the non machined surface is used as the rough base. When selecting the rough datum, the general purpose is to meet the requirement that the allowance after rough machining of important surfaces is small and average. When selecting the rough datum, the position error of the rough datum should be evenly distributed on the rough surface, and the rough datum should be as flat and intact as possible without gaps, which is conducive to setting the position.
When selecting the precision base, follow the principle of selecting the precision base. First, check whether the precision base plane can be easily positioned and clamped for processing. If a certain surface is selected as the precision base, the positioning method of the selected surface can be used uniformly to improve the processing efficiency when selecting other surfaces. Therefore, be careful when positioning the precision surface. The precision datum adopts the principle of precise coincidence, even if the unified positioning principle is used to position and finish other surfaces.
The principle for selecting the processing method of part appearance: For different part appearances, different part processing requirements, part construction characteristics, data properties, etc., the corresponding processing method shall be selected to process the part appearance. When confirming the part processing method, it is generally to confirm the final processing method of the part first, and then deduce and confirm the processing method of the previous process from the back to the front.
(1) Principle of economic applicability
When processing parts, first analyze the processing economy of the processing method, that is, analyze the selection of equipment, process, technicians, and processing time, that is, confirm the processing applicability, confirm the processing accuracy range, and the accuracy range should be compatible with the accuracy requirements and surface roughness requirements of the part surface processing, so as to ensure that the processed parts meet the requirements.
(2) Principle of matching production type
Different processing methods should be selected for different production types. High efficiency machine tools and advanced processing methods are often used for mass production, while the production methods of ordinary machine tools and conventional processing methods are generally used for parts produced in small batches.
(3) Matching principle of processing method
The processing method selected for mechanical processing of parts shall match with the shape accuracy and position accuracy of the machined surface, adapt to the part data, and adapt to the existing equipment conditions and workers' technical level. It is required to analyze the problems in detail, process according to the processing requirements and existing materials, and do not blindly match to cause processing failure.