Method and apparatus for the numerically controlled cutting of a single-start or multi-start thread in at least two thread-cutting passes

摘要

The workpiece (1) to be provided with a single-start or multi-start thread is held in a main spindle (3) which is driven in a rotary manner by a drive motor (4). A cutting tool (8) is fed in the direction of the X- or Z-axis by means of two feed drives (12, 13). So that the approach distance which the cutting tool (8) has to cover until the desired feed rate is reached in the Z-direction is now kept short, the acceleration to be adhered to during the first thread-cutting pass is determined before the start of this first pass. This acceleration is calculated on condition that the approach during each thread-cutting pass takes place with the greatest possible acceleration but without a predetermined, maximum acceleration being exceeded. Since the approach during the first cutting pass does not take place with any assumed acceleration, but the acceleration to be adhered to is precalculated, this ensures that in the following thread-cutting passes the acceleration to be adhered to corresponds at most to this maximum acceleration and yet the shortest approach distance possible under the given conditions to be adhered to is never exceeded. <IMAGE>