LIBRARY | START | BACK | NEXT
2-CNC Control - Continuous Path
The continuous-path control system is more commonly known as the contouring system. Its function is to synchronize the axes of motion to generate a predetermined path, generally a line or a circular arc. The contouring system has the capability of controlling its drive motors independently at various speeds as the tool moves towards the specified position. This involves simultaneous motion control of two or more axes which requires separate position and velocity loops.
The contouring capability of CNC is one of the primary reasons it was invented. Prior to NC if a contour was to be machined it had to be machined from a pattern on a tracing mill. In some cases a pattern was used just for roughing purposes and then a very large set of X and Y coordinates were calculated and printed out that would represent the curve. Two machinists were then used to operate a milling machine, one machinist on each axis, who would incrementally move each axis in unison to the proper coordinate printed out on their axis sheet. This was quite an improvement in accuracy over the pattern tracers but extremely time consuming and expensive. it didn't take much to go from there to replacing the machinist with servo motors reading the coordinate list from a punched tape. Thus, from necessity, was born Numerical Control. R.S.
LIBRARY | START | BACK | NEXT