Numerical control machining error △ addition is formed by programming error △ editing, machine tool error △ machine, positioning error △ fixed, tool setting error △ tool and other errors.
Namely: △number plus=f (△editing+△machine+△fixed+△tool)
in:
1. Programming error △ is composed of approximation error δ and rounding error. The approximation error δ is produced in the process of approximating a non-circular curve with a straight line segment or a circular arc segment, as shown in Figure 1.43. The rounding error is the error produced by rounding the coordinate value to an integer pulse equivalent value during data processing. Pulse equivalent refers to the displacement of each unit pulse corresponding to the coordinate axis. Normal-precision CNC machine tools generally have a pulse equivalent value of 0.01mm; more precise CNC machine tools have a pulse equivalent value of 0.005mm or 0.001mm, etc.
2. The error of the machine tool is caused by the error of the CNC system and the feed system.
3. The positioning error △ is always caused when the workpiece is positioned on the fixture and the fixture is positioned on the machine tool.
4. Tool setting error △ tool is generated when determining the relative position of the tool and the workpiece.
