Machining of the CNC
November 29, 2018
Before using the MasterCAM software to automatically program the parts for NC machining, firstly, the machining process analysis of the parts is carried out to determine a reasonable machining sequence, while ensuring the surface roughness and machining accuracy of the parts. It is necessary to minimize the number of tool changes, improve the processing efficiency, and fully consider the shape, size and machining accuracy of the parts, as well as the rigidity and deformation of the parts, so as to finish the roughing and then finish the machining; Machining other surfaces after machining the datum. The knives used are external turning tools, 5mm wide grooving knives and external thread turning tools. The process flow of the part on the CNC lathe is: contour machining, grooving machining, thread cutting and final cutting. If the part is programmed with a cycle command, the program includes the following parts: 1) the coordinate system and the specified program of the machining process parameters; 2) the roughing and finishing process of the contour cycle; 3) the grooving cycle machining program; 4) the thread Cyclic machining program; 5) Final truncation machining program.
Geometric modeling of parts
When modeling the part, it is not necessary to draw the model of the whole part. It is only necessary to draw the outline of the machined part. The machining size, geometrical tolerance and fit tolerance can be omitted, which saves modeling time. , can meet the needs of CNC machining; when modeling, should be drawn according to the actual size of the part to ensure the correctness of the calculated tool path coordinates; and different processing steps can be drawn in different layers, With the function of the layer in MasterCAM, when determining the tool path, it is called or hidden to select the contour required for machining.
Part machining tool path determination
After the part is modeled, according to the arrangement of the machining process, select the tool used in the corresponding process, select the machining blank according to the requirements of the part, and correctly select the workpiece coordinate origin, establish the workpiece coordinate system, and determine the relative relationship between the workpiece coordinate system and the machine coordinate system. Dimensions, and various process parameters are set to obtain the tool path for part machining. The MasterCAM system generates the corresponding toolpath process data file NCI, which contains all the set tool motion trajectories and machining information.
After the tool machining path is set, the machining simulation function provided by the MasterCAM system can be used to observe the cutting process. It can be used to check whether the setting of the process parameters is reasonable, whether there is interference in the actual machining of the CNC, and whether the operation of the device is correct. Whether the actual part meets the design requirements. At the same time, in the NC simulation processing, the system will give a report on the machining process. This can eliminate the trial cutting process in actual production, which can reduce material consumption and improve production efficiency.
The MasterCAM system itself provides more than one hundred post-processing PST programs. For different CNC equipment, the CNC system may not be the same, and the selected post-processing program will be different. For the specific numerical control equipment, the corresponding post-processing program should be selected. After the NC control code generated by the post-processing is properly modified, if it can meet the requirements of the numerical control equipment used, it can be output to the numerical control equipment for CNC machining.
Using MasterCAM software, it is easy to establish the geometric model of the part, quickly generate NC code automatically, shorten the programming time of the programmer, especially the NC program of complex parts, which can greatly improve the correctness and safety of the program, reduce the production cost and improve Work efficiency.
