Engineering Metrology: Automatic Dimensional Control

AUTOMATIC  DIMENSIONAL CONTROL
significant development in measurement over the years since the war has been the automatic dimensional control of both production and measuring equipment. This has been applied particularly to the control of machine tools and four main types of function have been developed. First, there is the straightforward control of the single dimensional size of a workpiece such as on a cylindrical grinder, where a gauging unit controls the machine cycle directly from the size of the workpiece as it is being produced. [bad word] systems of positional control such as those used for positioning the table of a horizontal or jig boring machine. Here, the dimensional information is set on numerical dials or fed in by punched cards which control the positions of the table for sequential machining operations. natural development of positional control has been the continuous path control of the machine table applied to profiling operations. This necessitates the continuous feeding in of numerical information from a magnetic or paper tape and the application of [bad word] to generate contours from co-ordinate data representing the outline required. In systems using magnetic tape, the profiles are developed on a [bad word] whose output is recorded on the tape in such a form that will control the machine tool direct. In systems using punched paper tape, a limited amount of basic data is stored on the tape and [bad word] of contours is carried out in the machine tool control unit or director.