Dec 27, 2019
The material processing of the part is 45 # steel, and the modulation processing is HRC26-36. The numerical analysis of the CNC car pin process is performed on this part.
Parts as shown:
Programming in small batch production conditions.
Gauze and emery cloth and file are not allowed to modify the surface.
No chamfering 0.5 × 45C.
Basic characteristics of NC processing technology
The machining process of NC machine tools is basically the same as that of ordinary machine tools, but NC machine tools are automatically processed, so they have the following characteristics: ① The process content of NC machining is more complicated than that of ordinary machine tools, with high precision and high surface quality , The processing content is richer. ② The programming of CNC machine tools is more complicated than that of ordinary machine tools. This is because the CNC machine tools have the characteristics of tool setting, tool changing, and retracting, which all become program content without exception. It is precisely because of this feature that the requirements for the correctness and rationality of the processing program are extremely high. The slightest mistake. Otherwise, qualified parts cannot be processed.
Before programming, we must perform process analysis on the part. This is an indispensable step. As shown in the figure, I will perform an accuracy analysis on the part, select a processing method, draw up a processing plan, and select a reasonable tool to determine the cutting amount. The part is composed of threads, cylinders, cones, arcs, grooves and other surfaces, among which there are stricter requirements for diameter and dimensional accuracy.
In order to facilitate the clamping, in order to ensure the accurate and stable positioning of the workpiece, reliable clamping, large support area, the right end of the part is threaded, and the largest diameter cylinder ф40mm in the middle section. The right end is a circular arc connected in sequence, obviously the right end is It is impossible to clamp the circular arc connection, so it should be left in the final processing. The left end cylinder and ellipse should be processed first by clamping the blank. Turning and clamping ф40mm cylindrical processing right end arc, the blank is ф45 * 120mm.
According to the shape of this part is a shaft type part, it is more suitable for machining on a lathe. Because the part has both grooving dimensional accuracy and arc numerical accuracy, it is difficult to guarantee its technical requirements on an ordinary lathe. Therefore, if we want to ensure the technical requirements, only machining on a CNC lathe can guarantee the dimensional accuracy and surface quality of its machining.
Determine the positioning reference and clamping method of the part
① In order to ensure the position requirements between the non-machined surface and the machined surface, the non-machined surface should be selected as the rough reference.
② Reasonably distribute the remaining amount of each machining surface, and select the rough outer circle as the rough standard.
③ Reuse of rough reference should be avoided.
④ The surface of the rough datum should be flat and free of defects such as gates, risers or flashes. For reliable positioning.
Precise selection principle
① The principle of datum coincidence: the design datum of the machining surface is selected as the positioning datum;
② The principle of unity of benchmarks, the benchmark principle of itself and the benchmark principle of each other.
To sum up, the principle of selecting coarse and fine benchmarks. Because it is a shaft component, only three grip chucks are required for positioning on a lathe. The positioning benchmark should be selected on the axis of the part. The right end face is used as the positioning reference.
CNC machine tools, like ordinary machine tools, must also select positioning references and clamping stresses throughout the design, process and programming standards to reduce the number of clamping, as much as possible after a positioning and clamping, all the surface to be processed to avoid Adopt the manual adjustment processing scheme of the machine to make full use of the effectiveness of the CNC machine tools. As far as possible, all or most of the machined surface should be processed by clamping. According to the analysis of the parts drawing, I should clamp one end of the bar of ф45mm blank and clamp the 38mm length to process the cylinder and ellipse. Process it to ф30mm at the right end of the part, and then unload the bar. Clamp a ф40mm cylindrical surface and machine the arc at the other end. In this way, all machining surfaces of the part can be completed in two clampings, and its machining requirements can be guaranteed.
Choice of processing method
The selection principle of the processing method is to ensure both the production efficiency and the processing cost under the premise of ensuring the processing accuracy and surface roughness of the processing surface. In actual selection, comprehensive consideration should be given to the shape, size, heat treatment requirements and existing sound field conditions of the part. Because this part is a shaft type part, it is more suitable for machining on a lathe. After analyzing the size of the part drawing, the dimensional accuracy is relatively high. It is difficult to guarantee the dimensional accuracy and surface roughness of ordinary lathes, so you should choose to process on CNC lathes.
Determination of processing plan.