Division of the most popular NC machining processe

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Division of NC machining processes and steps

(1) division of processes

machining parts on NC machine tools, processes can not be moved up and down to be more concentrated, and most of the years of development or all processes can be completed in one clamping. Generally, there are several ways to divide the process:

1) divide the process according to the clamping and positioning method of parts

because the structural shape of each part is different, the technical requirements of each processing surface are also different, so the positioning methods are different during processing. When machining the general shape, locate the inner shape; When machining the inner shape, it is positioned by the shape. Therefore, the process can be divided according to different positioning methods

the sheet cam shown in Figure 1 can be divided into two processes according to the positioning mode, and the first process can be carried out on ordinary machine tools. Position the machined end faces a and B on the outer circular surface and plane B Φ 22h7 inner hole, and then machine end face B and Φ Process hole of 4h7; In the second process, two machined holes and one end face are positioned, and the outer surface curve of the cam is milled on the NC milling machine

Figure 1 sheet cam Figure 2 turning parts

2) rough and plastic universal king one of the finishing division process

and has the characteristics of wide measurement range, high precision, fast response, reliable work

when dividing the process according to the processing accuracy, stiffness, deformation and other factors of the parts, the process can be divided according to the principle of separating rough and finish machining, that is, rough machining first and then finish machining. At this time, different machine tools or different cutting tools can be used for processing. Generally, in one installation, it is not allowed to finish machining a part of the surface of the part before machining other surfaces of the part. For the parts shown in Figure 2, most of the allowance of the whole part should be cut first, and then the surface should be finished again to ensure the requirements of machining accuracy and surface roughness

3) divide the process according to the tool used

in order to reduce the number of tool changes, compress the idle time and reduce unnecessary positioning errors, the parts can be processed according to the method of tool centralized process, that is, in one clamping, use the same tool to process all possible parts, and then change another tool to process other parts. This method is often used in special CNC machine tools and machining centers

(2) division of work steps

the division of work steps is mainly considered from two aspects of machining accuracy and efficiency. In a process, different cutting tools and cutting parameters are often used to process different surfaces. In order to facilitate the analysis and description of more complex processes, the process is subdivided into work steps. The following takes the machining center as an example to illustrate the principle of step division:

1) the same surface is completed in turn according to rough machining, semi finish machining and finish machining, or all machined surfaces are separated according to rough machining before finish machining

2) for parts with both milling surface and boring hole, milling surface first and then boring hole can be made to recover for a period of time, which can reduce the impact on hole accuracy caused by deformation

3) divide work steps according to tools. In some machine tools, the rotation time of the workbench is shorter than the tool change time. Work steps can be divided according to the tool to reduce the number of tool changes and improve the processing productivity

in short, the division of processes and steps should be comprehensively considered according to the structural characteristics and technical requirements of specific parts. (end)

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