Application of a New Straightness Measurement Method to Large Machine Tool

A new measurement method of straightness which will be called TSP method in the paper is applied to a larage horizontal boring and Milling machine for the purpose of developing its practical use. Principle of the method is that: the straightness can be obtained due to an algorithm using series of a pair of relative displacements between tool and objective which are measured at successive two points fed with the distance of two sensors. The algorithm was programmed in a micro-processor and the Method was compared with conventional ones such as laser instrumentation and collimator. It was shown that the measurement system satisfactorily works in easy adjustment, no need of skill, good repetitive accuracy, and simultaneous measurement for both tool motion and objective including cut surface. The errors which might be introduced by feed pitch, distance of the probes, the surface roughness, characteristics of the probes, and other factors are discussed. The analysis also shows that parallelness and flatness can be obtained simultaneously. The straightness of the cut surface could be improved by tool notion compensated with NC function. This made it possible to apply the method to combinations of different tool motions and objectives. The measurement for these combinations verified reliability of the method; the straightness obtained for a cut surface using two different tool motions agreed well each other.