Patent GB-717678-A (GB)
Title: Improvements relating to apparatus for the production of rulings such as those of diffraction gratings
Inventor: SAYCE LEONARD ALFRED
IPC: B44B3/02
Filed: 1951-04-16
Abstract: 717,678. Engraving ; ruling - machines. NATIONAL RESEARCH DEVELOPMENT CORPORATION. April 16, 1952 [April 16, 1951], No. 8858/51. Class 100 (2). . Straight, equally - spaced, parallel grooves or lines, such as a diffraction grating, are made on a surface by means of a scribing &c. tool, the surface and tool being moved in the following manner: (a) one element is continuously advanced with uniform motion in one direction (e.g. by a nut on a continuously - rotated lead - screw); simultaneously (b) the other element is reciprocated transversely to (a) with a motion controlled to enable the tool to make equally-spaced parallel markings on the surface,. each of which is at least over part of its length substantially straight (e.g. a rapid acceleration and deceleration at the ends of the working stroke, the main part of the stroke being steady). In the apparatus shown in Fig. 1 a diamond tool 36 carried by a scribing device 25, incorporating a nut component as described in Specification 684,846, is steadily advanced by a continuously rotating stainless steel lead-screw 10, while a carriage 5, holding a metallized glass plate 6 to receive a diffraction grating, is reciprocated along runners 3, 4 by a cam 48 on a shaft 15 rotated synchronously with the lead-screw 10. The cam contour is such as to give a simple harmonic motion during the idle (return) stroke and a rapid acceleration, a long steady movement, and a rapid deceleration during the working stroke W, cams a, b on the shaft 15 operating switches to lift the tool 36 electromagnetically from the plate 6 during all but the long steady movement. The shaft 15, belt-driven by an electric motor 12, may be coupled by spiral gearing 19, 20 to the rod 10, or a separate motor may be provided for the latter electrically synchronized with the motor 12; the gearing 20 shown drives a spider 21 having radial pins such as 22 holding a socket 24 for the rod 10; the bearings for the rod 10 in brackets 8, 9 may be nut components, as described in Specification 684,846, engaging fine ring grooves G1, G2 on the rod 10; one of these sets of grooves may be omitted. The scribing device 25, Fig, 3, has an arm 29 with a roller 30 engaging a track bar 31 fixed across the carriage runners 3, 4, and an arm 32 carrying a cross-strip hinge 33a for the tool arm 34, an initial setting screw 41, and the tool-lifting magnet 39; the tool arm 34 is connected to an oil dashpot 37 and has an adjustable counterweight 40. A grating having 5000-15,000 lines to the inch may be produced using a leadscrew 10 of a corresponding number of threads to the inch, or a 5000 grating may be produced from a 15,000 lead-screw by keeping the tool 36 lifted from the plate 6 during two out of every three strokes W. The carriage 5 may be driven by the lead-screw 10 while the tool 36 is driven by the cam 48. According to the Provisional Specification, instead of the straight link connection 58 between the cam follower slide 51 and the carriage 5, a rectangular loop belt system may be provided.