Patent GB-516293-A (GB)
Title: Improvements in or relating to optical measuring or testing apparatus
IPC: G02B21/00
Filed: 1938-06-29
Abstract: 516,293. Optical gauging apparatus. KAPELLA, Ltd., WARMISHAM, A., and REASON, R. E. June 29, 1938, Nos. 19209/38, and 21845/39. [Class 106 (ii)] [Also in Group XX] In projection apparatus for examining the profile of an oblique or curved section of an article, means is provided to impart to the article and to the projection device, or a part thereof, relative movement about an axis, so that points on the profile successively pass through the object plane of the apparatus. Fig. 1 shows apparatus for investigating form of milling cutter A having four helical cutting edges and rotatably mounted between centres A<SP>1</SP>, A<SP>2 </SP>supported on a slide A. One cutting edge is engaged by a bar E and the cutter is rotated during movement of the slide by a spring A<SP>4</SP> attached to a lever secured-to the cutter spindle. The edge under examination is arranged in a colliminated beam of light projected from an illuminating device comprising a lamp C<SP>1</SP>, condenser C<SP>2</SP>, and an objective C<SP>3</SP>, plates C<SP>4</SP>, C<SP>5</SP> having vertical slots being placed 'adjacent the condenser and the objective. The beam is projected on to a photographic plate F by a lens system D<SP>1</SP>, D<SP>2</SP>, the plate being moved laterally with, but in opposite direction to, the  slide A' by a link F' mounted on a point F<SP>2</SP>.  In a modification, the photographic plate is replaced by a graticule G, Fig. 4, carried by a slide F<SP>3</SP> whereby direct measurements may be made of the form of the cutting edge by visual observations of the graticule through a microscope G<SP>1</SP>. The microscope is adjusted vertically by a pivoted lever G<SP>2</SP> the movement of which under the influence of a spring G is limited by a pivoted lever G' one end of which abuts against acutting edge disposed opposite that under investigation. The graticule may bear a curve correspondong to the correct form of the cutting edge with which the actual form may be compared. In another arrangement, the-illuminating device C 1 , Fig. 6, and the bar E are mounted on a slide C<SP>6</SP>, while the motion of the cutter is limited to rotation. As shown in Fig. 7, the illuminating device C, bar E, and the projector are stationary, while the cutter .and the photographic plate are mounted on the slide A'. In this case the projector, which is arranged "to give unit magnification, comprises an objective D', colliminating lenses D' arranged as in Specification 498,419, [Group XX], and mirrors D<SP>5</SP>, D<SP>6</SP>. The lense D<SP>4</SP>  adjacent the plate F may be omitted. In another modification, the cutter A, Figs. 9, 10 and the plate F are stationary, while the illuminating device C, bar E and the projection system D are mounted to slide as a unit, the device C, which includes a mirror C<SP>7</SP>, being connected by a bracket H to the projector which is moved by a screw H' rotated through pulley gearing from a motor disposed in the space between the end supports B<SP>5</SP> of the apparatus. The centres for supporting the cutter are adjustable in vertical slides A<SP>8</SP>, A' and rotating of the cutter is effected by a weighted arm A'. In a further arrangement, the cutter and the plate F are mounted on a fixed base, while the projection system is carried by a slide and includes a mask having a vertical slot limiting the projected image. In an apparatus for projecting helical cutting edges of a worm-cutting hob, the hob L, Figs. 14, 15, is supported between vertically adjustable centres mounted on a slide L<SP>3</SP> supported by a base B within which is mounted a photographic plate F The projection system D is connected by a cranklike frame O<SP>1</SP> to the base which also supports a slide C<SP>6</SP> on which is pivoted an arm C<SP>9</SP> carrying the illuminating device C. The hob is moved laterally during its rotation by a fixed arm L<SP>6</SP> carried by a slide L' and engaging a helical groove L<SP>5</SP> in a sleeve secured to the hob spindle the pitches of the groove and hob being the same.