GB1012711A - Improvements in or relating to surface testing apparatus - Google Patents

Abstract

1,012,711. Gauging surfaces. RANK PRECISION INDUSTRIES Ltd [trading as TAYLOR, TAYLOR & HOBSON]. May 30,1962 [May 30, 1961], No. 19465/61. Heading G1M. Departure from circularity in a workpiece is measured by a stylus E 1 of a pick-up head E (electromagnetic, electrostatic or piezoelectric) which is carried on a bracket D and which explores the workpiece surface as the spindle A, to which bracket D is adjustably clamped, rotates. Spindle A is held in bearings on the underside of the worktable support B<SP>1</SP> and the base-part B<SP>2</SP> and is driven by a motor through a selectively variable (using knob B<SP>3</SP>) reduction gear box including a friction-wheel and disc for continuous variation according to the size of workpiece. In this way, a constant peripheral speed of the stylus may be obtained so that consistent readings will be obtained on an integrating meter optionally connectable to the pick-up to give the average surface roughness. Limit switches carried (within the housing B<SP>4</SP>) by the rotating spindle A co-operate with adjustable pins G<SP>1</SP> and G<SP>2</SP> to limit the arc of stylus movement. The stylus is finely adjustable in the mounting-block D<SP>1</SP> by a screw D<SP>3</SP>, the block D<SP>1</SP> being itself movable in a guideway for coarse adjustment. The workpiece i s centred with respect to the spindle axis using a notched locating plate C<SP>2</SP>, adjustable in two-dimensions by screws C<SP>4</SP> and C<SP>5</SP>, and a microscope F; the worktable C is supported at three points on sliding pads. In making measurements, two different speeds of rotation of spindle A may be used to give error graphs corresponding to fine and coarse surface structure. For 'average' measurements a cam shaft is connected via a clutch, with the spindle drive for sequentially operating switches to connect in the integrating meter and then to disconnect the clutch after a pre-determined stylus movement. Disconnection of the cam-shaft from the spindle drive for normal measurements returns the integrating meter to zero. For measurements on internal concave surfaces, a stylussupporting bracket as shown in Fig. 8 is used. Specifications 716,719 and 1,012,712 are referred to.