What content should be considered in the preparation of machining process for shaft parts of precision machinery parts? This is in the processing of shaft parts will encounter problems, but also in the formal start of processing should be considered, only in advance of full preparation, in order to carry out the correct numerical control machining or mechanical processing of shaft parts, so as to avoid mistakes in processing, improve processing efficiency.
The process analysis of NC machining should be carried out on the part drawing. The specific content is as follows:
(1) Whether the dimensioning method in the parts drawing is suitable for the characteristics of CNC machining;
(2) whether the geometric elements constituting the outline in the parts drawing are sufficient;
(3) Whether the reliability of the positioning datum is good;
(4) Whether the machining accuracy and dimensional tolerance required by the parts can be guaranteed.
For the blank of parts, it is also necessary to carry out manufacturability analysis, specifically:
(1) Analyze the adaptability of blank in installation and positioning, as well as the size and uniformity of allowance;
(5) Whether the blank processing allowance is sufficient and whether the allowance is stable during mass production.
1. Selection of machine tools
Different parts should be processed on different CNC machine tools, so choose CNC machine tools according to the design requirements of parts.
2. Selection of tool point and tool change point
Tool point: is the starting point of tool movement relative to the workpiece in exponential controlled machining.
Tool change point: is set for machining center, CNC lathes and other multi-tool machining machine tool programming.
In programming is to see the workpiece is static, and the tool is in motion. The tool point is usually called the program origin, the main points of selection are: easy to find the right, convenient programming, small error to the tool and processing inspection is convenient and reliable, in the tool should make the tool point coincide with the tool point.
3. Selection of processing method and determination of processing scheme
The selection principle of machining method is to ensure the machining precision and surface roughness requirements of the machined surface, but in the actual selection, it should be combined with the shape, size and heat treatment requirements of the parts.
When the machining scheme is determined, the machining methods needed to meet these requirements should be preliminarily determined according to the precision and roughness requirements of the main surface.
4. Selection of processing allowance
Machining allowance: The quantity generally refers to the blank solid size and part size difference.
The selection of machining allowance has two principles, one is the principle of minimum machining allowance, the other is that there should be sufficient machining allowance, especially for the last process.
5. Determination of cutting parameters
Cutting parameters include cutting depth, spindle speed and feed. The cutting depth is determined according to the rigidity of the machine tool, fixture, tool and workpiece, the spindle speed is determined according to the allowable cutting speed, and the feed is determined according to the machining accuracy and surface roughness requirements of the parts and the material properties of the workpiece.