Patent GB-553791-A (GB)
Title: Improvements in or relating to gauges for internal measurements
IPC: G01B7/13
Filed: 1941-11-03
Abstract: 553,791. Linear-dimension gauges. KAPELLA, Ltd., and COOKE, E. A. Nov. 3, 1941, No. 14145. [Class 106 (ii)] Comprises two relatively movable elements to engage opposite sides of the bore, an electromagnetic device or devices the circuits of which are varied by this relative movement and hence an indicating or recording instrument affected, a support for the workpiece, and a guide or guides allowing relative movement between workpiece and gauging elements in the direction of the axis of the bore. Figs. 1 and 2 show the device adapted to measure small bores. A bracket B projects from the casing A housing the electromagnetic device and is of T-section in the angles of which are formed guide tracks B 1 , B 2 , a third track B3 being cut in the top surface of the bracket. A saddle C slides on balls in these tracks and is provided at the front with two vertical posts C<SP>1</SP> to the top and bottom of which are attached flat spring strips C<SP>2 </SP>extending to another pair of posts D<SP>1</SP> which carry between them a workpiece support in the form of a V-block, the tube E or work-piece being parallel to the guide tracks B<SP>1</SP>, B<SP>2</SP>, B3. A spring clip D<SP>2</SP> holds the tube in position and a stop D3 prevents excessive loading of the spring strips. A spindle F is fitted into the front wall A<SP>1</SP> of the casing and is provided with a part F<SP>1</SP> projecting forward into the tube E. The part F<SP>1</SP> has a feeler F<SP>2</SP> which engages the bottom surface of the bore of the tube with a pressure furnished by the spring strips. A second feeler G opposite the feeler F<SP>2</SP> engages the upper surface of the bore and is carried by a lever G<SP>1</SP> fulcrummed on a spring ligament G<SP>2</SP> which exerts a slight force to keep the feeler in engagement with the tube. The end of the lever G<SP>1</SP> away from the feeler forms the armature H of the electromagnet device located between E- shaped cores H<SP>1</SP> the centre limbs having coils H<SP>2</SP> connected in series in the secondary circuit of a transformer (not shown). The junction of the coils is connected through a meter to a tapping point on a resistance across the secondary. A pair of weights may be mounted on arms H4 projecting laterally from the armature to damp vibrations. In a second form, for larger bores, the workpiece is placed on a horizontal turntable on a support and a screw operated slide carrying the two feelers and the magnetic device may be moved vertically up and down through the bore. In a third form shown in Fig. 7, the work N is supported on a base N<SP>1</SP> carrying vertical guide tracks N<SP>2</SP> for a cross member O carrying horizontal tracks for gauging heads PQ. These may be moved to and away from one another by a differential screw O<SP>1</SP> controlled by a handwheel O<SP>2</SP> fitted with a micrometer. Each gauging head contains an armature lever P<SP>1</SP>, Q<SP>1</SP> fulcrummed on a spring ligament P<SP>2</SP> or Q<SP>2</SP> and carrying feelers P<SP>3</SP>, A3. The coils between which the armatures move are arranged in a bridge circuit with a meter.