Patent GB-572144-A (GB)
Title: Improvements in or relating to measuring apparatus for copying machines and other purposes
IPC: B24B49/12
Filed: 1943-07-16
Abstract: 572,144. Optical-projection apparatus. KAPELLA, Ltd., and COOKE, E. A. July 16, 1943, No. 11623. [Class 97 (i)] [Also in Groups XIX, XXII and XXIII] In a copying - machine wherein relative motion is effected between a tool support and a work support in accordance with the relative movements of a tracer or datum and a pattern support, measuring apparatus is provided comprising one or two fixed perpendicular scales whose origin constitutes the tracer or datum, a squared grid having lines parallel to the scales and movable with the pattern support and one or two movable fine-setting scales which are perpendicular to each other, but inclined to the grid lines, all the scales being superimposed in the plane of the grid. The machine comprises a frame A on which a table B is movable transversely by a handle B3, a carriage C being movable longitudinally on the table by a handle C<3>. Transparent scales B 5, C <5> on the table and carriage are illuminated from below and co-operate with indices on the machine frame and table to indicate the settings. The work is mounted on a table C<8>, Fig. 3, angularly adjustable on a shaft C<2> rotatable in bearings on the carriage C and carrying a drum D by which it is connected through toothed gears D<1>, D3 with a hollow shaft D<2> carrying the pattern support G. A worm D<6>, hand operated at D', provides for rotation of the work and pattern and may be disconnected by a handle D<8> to allow free rotation within the carriage C. The table C<8> is rotatable by a handle C<15>. The axes of the shafts C<2>, D<2> lie in a plane referred to as the neutral plane when the table B and carriage C are set at the zeros of the scales B<5>, C<5>, and this plane also contains the operative edge of the cutter E and the optical axis of a microscope E<2> carried by a fixed arm E<6> and directed to view the operative edge of the cutter. A spider D<10> is angularly adjustable on the shaft D<2> and has mutually perpendicular arms D<11> carrying thumb-screws D<12> for the adjustment of perpendicular superimposed slides D<15>, D<16>. A hood F<1> on the upper slide D<16> has a central aperture F<3> in which a disc F <5> is secured by studs F<4> and carries a spring finger for securing a pattern support F against fences F<9>. The pattern, which may consist of a photographic transparency on the support F, may thus be adjusted angularly and translationally relatively to the shaft D<2>. A carrier D<9> fixed on the shaft D<2> carries a transparent plate G inscribed with spaced cross-lines forming a grid similar to squared paper whose origin lies at the axis of the shaft, and an image of the grid, together with the images of scales imposed thereon by optical apparatus H, is projected onto a translucent screen E<10>, Figs. 1 and 12, by reflectors E<9>, E<11>, and a projection objective E<8> mounted on a fixed bracket E' so as to be coaxial with the shaft D<2> and in the neutral plane. The apparatus H comprises a fixed casing containing a source of light G<8> and a stationary graticule G<3> carrying two perpendicular scales G<4>, G<5> parallel to the grid lines and whose graduations show sub-divisions of the spaces between the grid lines G<1>, G<2>, the distance of the origin O of the scales G<4>, G<5> from the optical axis of the work microscope E<2> being exactly equal to the distance separating the axes of shafts C<2>, D<2>, and thus forming a tracer for following the outline of a pattern on the support F. Two further graticules H <5>, H‹ are provided with fine setting scales which are perpendicular to each other, but are inclined to the grid lines and the scales G<4>, G<5> at an angle whose tangent is one of the scale divisions divided by the length of the scale. Each scale H<5>, H<6> is movable in a direction parallel to the grid lines so that movement of the carriage C to cause one of the grid lines to move its intersection with the scale H<5> or H<6> by a number of sub-divisions of the latter scales will move the carriage and consequently the work and pattern through a distance equal to the corresponding number of sub-divisions of the divisions of the scales G<4>, G<5>. Units of adjustment of the work are thus provided by the scales B<5>, C<5>, and successive sub-divisions of these units by the grid lines, scales G<4>, G<5> and scales H <5>, H<6>. The scales H <5>, H<6> are mounted on slides J, Fig. 8, which are movable on perpendicular guides in the casing H by means of ball tracks J<3>, J<4>, whereof the balls J<3> engage concave guides on the slides to determine their directions of motion, whereas the balls J<4> engage flat surfaces on the slides. Adjustment of the slides is effected by ball-ended rods J<5> engaging grooves in discs J<7> rotatable within the casing H by worms J<8> actuated by handles A<6>, A<7>. Springs J<10> tend to move the slides into the central positions in which the intersection of the scales H <5>, H<6> coincides with the origin O, but either may be withdrawn from the field of projection to allow adjustments of the grid to be effected without interference by the scale not in use, or both graticules may be withdrawn as shown in Fig. 12. The scales are imaged on the grid by optical systems H<2>, H3, and according to the Provisional Specification one of these may be arranged with a horizontal eye-piece. Specifications 499,751 and 570,494, [both in Group XXII]. are referred to.