The basic concept of CNC programming
When processing parts on the CNC lathe, it is generally necessary to first write the parts processing program, that is, the instruction code in digital form to describe the process of the part being processed, the size of the part and process parameters (such as spindle speed, feed rate, etc.), and then the parts processing program into the CNC device, after the computer processing and calculation, issue a variety of control instructions, control the movement of the machine tool and auxiliary action, automatically complete the The processing of parts. When changing the processing object, just re-write the parts processing program, and the machine itself does not require any adjustment to the parts can be processed.
This is based on the drawings of the parts to be processed and their technical requirements, process requirements and other necessary information for cutting and processing, according to the instructions and format of the CNC system to prepare a sequence of CNC processing instructions, is the CNC machining program, or parts program. To be processed on the CNC machine tool, CNC machining program is necessary. The process of preparing the CNC machining program is called CNC machining programming, referred to as CNC programming (NC programming), which is an extremely important work in CNC machining.
Introduction to CNC programming methods
CNC programming methods can be divided into two categories: one is manual programming; the other is automatic programming.
(1) manual programming
Manual programming refers to the preparation of the various steps of the part CNC machining program, that is, from the analysis of the part drawing, process decision, determine the processing route and process parameters, calculate the tool track coordinate data, write the part of the CNC machining program list until the program inspection, are completed by hand. For point processing or geometry is not too complex plane parts, CNC programming calculation is simple, not many program segments, manual programming can be achieved. But the contour shape of the plane parts consisting of complex curves, especially the space complex surface parts, the numerical calculation is quite tedious, the workload is large, easy to make mistakes, and it is difficult to proofread. According to statistics, for complex parts, especially surface parts processing, with manual programming, a part of the programming time and the actual processing time on the machine tool ratio, an average of 30:1. CNC machine tools can not start the reason, there are 20% to 30% is due to the processing program can not be prepared in time and caused. Therefore, in order to shorten the production cycle, improve the utilization of CNC machine tools, effective solution to a variety of molds and complex parts of the processing problem, the use of manual programming can no longer meet the requirements, but must use automatic programming methods.
(2) Automatic programming
When carrying out complex parts processing, the calculation of tool trajectory is very large, and in some cases, even impractical. How to use computer technology to assist people with machining programs has led to the development of automatic programming technology.
Automatic programming can be divided into automatic programming methods based on automatic programming languages and automatic programming methods based on computer-aided design with graphic interaction, depending on the input of programming information and the way the computer processes the information.
The automatic programming method based on language is an early automatic programming method, in programming the programmer is based on the programming manual of the CNC language used and the part drawing, in the form of language to express the processing of all the content, and then input all of this content into the computer for processing, to produce the machining program can be used directly for CNC machine tools. Computer-aided design-based graphical interactive automatic programming method is a common method of modern CADCAM integration, in programming the programmer first to the part drawing for process analysis, to determine the composition of the program, followed by the use of computer-aided design (CAD) or automatic programming software itself part modeling function, build out the geometry of the part, followed by the use of computer-aided manufacturing ( CAM) function, the completion of the process plan designation, cutting amount selection, tool and its parameters set, automatically calculate and generate the tool path file, the use of post-processing functions to generate a specific CNC system with machining programs, this automatic programming method is called interactive programming graphics. This automatic programming system is a combination of CAD and CAM automatic programming system.