Analysis of CNC turning process

Analysis of CNC turning process

The analysis of CNC turning process is the preliminary process preparation for CNC turning. The rationality of the process has a significant impact on programming, machining efficiency of the machine tool, and machining accuracy of the parts. In order to develop a reasonable and practical machining program, programmers not only need to understand the working principle, performance characteristics, and structure of CNC lathes. Master programming language and format, master workpiece processing technology, determine reasonable cutting parameters, and correctly select cutting tools and workpiece clamping methods. Therefore, general process principles should be followed, combined with the characteristics of CNC turning, to conduct a detailed analysis of CNC turning technology. Its main content includes: analyzing the machining requirements and rationality of parts based on drawings; Determine the clamping method of the workpiece in CNC machining; The machining sequence of each surface, the feed path of the tool, and the selection of the tool, fixture, and cutting parameters.

Part drawing analysis is the primary task in formulating CNC turning processes. The main analysis includes dimension annotation methods, contour geometric elements, accuracy, and technical requirements. In addition, the rationality of part structure and processing requirements should be analyzed, and process benchmarks should be selected.

1. Analysis of dimension annotation methods

The dimension annotation method on the part drawing should adapt to the characteristics of CNC machining, using the same benchmark to annotate dimensions or directly providing coordinate dimensions. This marking method is not only convenient for programming, but also conducive to the unity of design basis, process basis, measurement basis, and programming origin. If there is no unified design basis for the dimensions in all directions on the part drawing, it can be considered to choose a unified process basis without affecting the accuracy of the part. Calculate and transform each dimension to simplify programming calculations.

2. Analysis of contour geometric elements

In manual programming, the coordinates of each node should be calculated. During automatic programming, all geometric elements of the part contour should be defined. Therefore, when analyzing part drawings, it is necessary to analyze whether the given conditions of geometric elements are sufficient.

3. Analysis of accuracy and technical requirements

Only by analyzing the machining methods and roughness of the parts can the machining accuracy and precision of the parts be analyzed. Its main content includes: analyzing the accuracy and whether various technical requirements are complete and reasonable; Analyze whether the CNC turning accuracy of this process meets the requirements of the drawing. Otherwise, it is allowed to use other processing methods for compensation and reserve margin for subsequent processes; The surface with positional accuracy requirements on the drawing should be clamped in one go; For surfaces that require high surface roughness, constant linear speed cutting should be used (note: when turning the end face, the spindle's maximum speed should be limited).

The clamping and positioning of workpieces in CNC turning, in which all or most of the machined surfaces are machined as much as possible after one clamping, and the number of clamping times is minimized to improve machining efficiency and ensure machining accuracy. For shaft parts, the outer cylindrical surface of the part itself is usually used as the positioning reference; For sleeve parts, the inner hole is the positioning reference. In addition to the universal three jaw automatic centering chuck, four jaw chuck, hydraulic, electric, and pneumatic fixtures, there are also various specialized fixtures with good universality. Reasonable selection should be made in actual operation.

Precision machining