Analysis and Research on Processing Technology of Typical Parts of CNC Lathe

The formulation of CNC machining technology is the most critical step in CNC lathe machining. Whether the process is reasonable directly affects the quality and processing efficiency of the product.

Taking the practical operation test questions of the 2014 Shandong CNC Car Skills Competition as an example, it is the key factor for success to analyze the dimensional accuracy and shape accuracy of the parts and formulate a reasonable processing technology. Figure 1 Parts processing content includes outer circle, stage, inner hole, outer arc surface, ellipse surface, inner and outer conical surface, groove, internal and external thread, etc., most of the dimensions have tolerance requirements and high precision from 0012 to 003mm The parallelism and coaxiality requirements of the isomorphic tolerance are also very high. The surface roughness of the critical dimension is Ra08.1. Analysis of the machining route In order to ensure the accuracy of parallelism and coaxiality, the left end of the rough machining should be 7030mm and then clamped. The size of the right end of the outer rough turning machine is turned around to finish the size of the left end. Finally, the two centers of the inner cone are positioned to finish the size of the right end. The origin of the machining coordinates at both ends of this part is set at the intersection of the two ends and the axis of the workpiece. The process route is as follows:

1) The right end of the three-jaw chuck clamps the workpiece, and the left end of the rough car has a length of about 60mm. a The outer circle of the rough car parts is 7030mmb. The finishing surface of the rough car parts is left with a finishing allowance of 03mm; C, the bottom hole of the 20mm drill is 46mm deep

2) The U-turn clamps a 030mm outer circle. a. The total length of the rough car end surface is guaranteed. Note that there is a margin of 0.3mm on the left end. The rough car outer circle is quasi 80105mm, quasi 67405mm, quasi 415.5mm, quasi 3124.mm. C drills a quasi 20mm bottom hole depth 25mm; d rough and fine car inner hole to size Inner hole chamfer 60.

3) U-turn holding 6740.5 outer garden. aThe total length of the end face of the precision car is guaranteed; b The internal groove of the precision car, the internal thread M3015 to the size κ internal hole of the precision car, and the Morse No. 5 inner cone to the size; d The external circle of the precision car is 78 and the radius of the R13 is to the size; e drill is accurate The bottom hole of 20mm is 25mm deep.

4) Turning the Morse No. 5 cone plug as the two centers of the front center to hold the turning right parts. a Turn the outer circle, arc, ellipse and cone surface with G73, macro program b Turn the two grooves to the size; κ coarse and fine thread M301.5 to the size. Software can also be used to automatically program the size of the right end portion, which is conducive to the connection of the processed surfaces. The inner hole at the right end can also be arranged in the final machining, which is beneficial to improve the rigidity of the workpiece. At the competition site, some players did not choose the above processing route, but first roughed the right end of the size, then gripped the right end of the rough finish of the left end of the size, and finally clamped the left end of the right end of the size of the right end. size. It is difficult to guarantee the parallelism and coaxiality of this processing technique by using the method of aligning. The test piece also confirmed that the irrationality of the process is not only poor in parallelism and coaxiality, but also the length of the quasi-78 outer circle.

2 Tool selection

Reasonable processing technology is conducive to the selection of the tool. The tool required for this part has a rough outer turning tool, two inner holes, an inner groove, an inner thread turning tool, an outer circular groove, an outer mule turning tool, and a twist. 1 drill. The CNC lathe uses a 4-station square electric tool holder that can only install 4 tools at a time, so the order of the tools must be arranged to avoid multiple installations and additional time. According to the processing route, first install the outer rough turning tool and then remove the rough turning tool, and then install the finishing turning tool.