GB475323A - Improvements in and relating to measuring apparatus and machine-tools - Google Patents

Abstract

475,323. Measuring - machines. SOC. GENEVOISE D'INSTRUMENTS DE PHYSIQUE. April 3, 1937, No. 9518. Convention date, May 26, 1936. [Class 106 (ii)] A scale 1 for use with measuring-machines or machine tools is protected by locating the scale in a casing 2 provided with a cover 5 arranged for movement in the longitudinal direction relatively to the scale and provided with a reading opening 8 under which the graduated length of the scale may pass without the casing being uncovered. The cover 5 is constituted by a metallic band 5 guided over pulleys 4<1>, 4<11> rotatably mounted on shafts 31, 311 carried by the ends of the casing. The band is provided with an opening 8 over which is a fitting 7 connected by an elastic tube 10 to the objective 11 of a microscope carried by the bed. When the carriage 16, upon which the casing and scale are mounted, is displaced, the casing 2, pulleys 4, and scale move while the part of the band 5 bearing the fitting 7 remains stationary and the opening is steady under the microscope while the whole scale passes. For some machines the total travel of the carriage is longer than the length of the scale, and several microscopes located at convenient distances along the path for the carriage are used. In a modification, the fitting 7 is closed by a piece of optically flat parallel glass. The band may not be fixed to the bed, but one of the pulleys 41, 411 may be rotated by hand to bring the opening under the microscope. An index carried by the band may co-operate with a coarse scale on the carriage. Opposite this index is an index fixed to the bed. The band could be replaced by a plate.