When CNC machining spherical surface is more and more quadrant ball and surface, due to improper adjustment, it is very easy to produce shoulder, shovel back and other conditions. The reasons are as follows:
1. System gap formation
In the driving pair of CNC machining equipment, there is a certain gap between the lead screw and the nut. With the increase of the time when the equipment is put into operation, the gap increases gradually due to wear. Therefore, the key factor for the shoulder on the machining surface is to compensate for the corresponding gap during the reverse movement. The clearance measurement usually adopts dial indicator measurement method, and the deviation control is within 0.01-0.02MM. It should be pointed out here that the base and rod should not be extended too long, because the cantilever is long, the base is easy to be moved by force, resulting in inaccurate counting, and the compensation value is not true.
2. Uneven formation of workpiece machining allowance
Before finishing the design surface of CNC machining parts, whether the machining allowance of the surface to be machined is average is also an important reason for forming whether the forming surface can reach the design requirements, because the machining allowance is not uniform, which is easy to form a “reflection” deviation. Therefore, for the parts with high requirements on surface form, before forming, the machining allowance should be as average as possible to reach the design requirements by machining one more profile.
3. Improper tool selection
In the cutting process, CNC cutting tools remove the raw materials through the main cutting edge. However, after the arc passes the quadrant and the arc is tangent to the cutting edge (the intersection of the back edge and the base surface), the cutting may be added to the back edge. Therefore, when choosing or grinding tools, we must study the wedge angle of the tools.
