GB1192933A - Method of and Apparatus for Inspecting Surfaces of Articles, such as Cathode Ray Tube Plates - Google Patents

Abstract

1,192,933. Pneumatic gauging apparatus; electric correspondence control systems. A.T. RANSON (Owens-Illinois Inc.) May 30, 1967 No. 24771/67. Headings G1M and G1N. In apparatus for inspecting the internal surface S of a cathode ray tube face plate, the face plate is lifted on a support to a position where it is rotated relative to a plurality of nozzle assemblies 24 radially spaced over the surface S. Each nozzle assembly includes a portion 34 provided with a stem 26 slidably mounted in a fixed housing 27, and pressure fluid is supplied to each assembly outlet, the stem 26 being elevated a distance above the face plate by the combined forces of ambient pressure on the portion 34 and of fluid issuing from the assembly and flowing between the surface S and the portion 34. Variations in the surface are sensed by a differential transformer associated with a respective nozzle assembly, the armature of each transformer being connected to its respective stem 26. Signals from each transformer are indicated on a recorder 38 and when any one nozzle deviates above a predetermined amount, a reject indicator is actuated. Each nozzle assembly may have its associated transformer fixed to the housing, and the ambient pressure on the nozzle may be supplemented by a light spring (101), Fig. 10 (not shown). Alternatively the ambient pressure force may be replace by an applied fluid pressure force, Fig. 16 (not shown). An electrically controlled pneumatic circuit for the nozzle assemblies is also described, Figs. 11 and 12, (not shown). Figs. 13-15 (not shown) illustrate how the thickness of articles may be gauged using the nozzle assemblies, but these form no part of the invention.