Patent GB-618072-A (GB)
Title: Improvements in the profiling of grindstones
IPC: B24B53/085
Filed: 1946-08-28
Abstract: 618,072. Profiling grinding-wheels. SOC. ANON. DE RECTIFICATION ET D'ENGRENAGES PROCEDES MINERVA. Aug. 28, 1946, No. 25841. Convention date, Sept. 26, 1940. [Class 60] An apparatus for forming the wheels used in machines for grinding gear teeth to a cross-sectional shape of which a part, at least, is substantially involute, comprising a slider controlling the shaping member and rolling without sliding on a base circle, is characterised by the fact that it is provided with a second slider which carries the shaping member and is mounted on a support adapted to move parallel to the first slider, said second slider being connected to said first slider by a lever oscillatably mounted on said support, and said lever being located between the points of attachment of said sliders, the fulcrum of said lever and the axis of said base circle forming a plane which is constantly parallel to the sliders. A quadrant 21 is fixed on a shaft 20 keyed to an arm 70 pressed against an abutment 71 by a powerful spring 72. A support 23 rockable about the shaft 20 carries, pivoted at 24, a lever 25 connected at one end, by a pivot 51 to a slider 26 movable in guides 27, 28 in the support 23 and rolling without slipping on the quadrant 21. The lever 25 is connected at its other end, by a pivot 18, to a slider 17<SP>1</SP> carrying a forming tool 50 and sliding in a carriage 11 adjustable on the support 23. The slider 26, a line joining the axis of the quadrant to the pivot 24, and the slider 27<SP>1</SP> are always parallel so that as the slider 26 rolls on the quadrant the motion of a point thereon is transmitted to the forming tool. The slider 27<SP>1</SP> does not directly support the tool 50, but supports a stirrup 47 to which is pivoted, at 48, a second, radiussing, stirrup 49 carrying the tool 50, an adjustable abutment 53 on the stirrup 49 contacts the stirrup 47, and an abutment 56 on the stirrup 49 is engaged by the end of a rod 60 having a nut 63 thereon kept pressed against a face on the carriage 11 by a spring 65. A bent lever 58 pivoted at 57 to the carriage 11 is connected at one end to a sleeve 61 locked on the rod 60 and is formed at its other end with a handle 31. The shape of the section to be formed may comprise, Fig. 2, an involute part cd, a tooth bottom ab, a radiussed part cb, and a chamfer de. On lowering the handle 31 from the position shown in Fig. 1, where an adjustable abutment 67 contacts the quadrant 21, the support 23 pivots about the shaft 20, the nut 63 being held against a face on the carriage 11, and the slider 26 rolls on the quadrant 21 so that the involute cd is formed. When the tool reaches the point d, an adjustable cam 14 on the slider 26 engages the guide 28 which modifies the motion so that the chamfer de is formed. When, from the position shown in Fig. 1, the handle 31 is raised, the support 23 is held stationary against the quadrant 21, by the stop 67, so that the rod 60 is moved to turn the stirrup 49 so that the tool 50 radiusses the part cb until the sleeve 61 abuts a face of the carriage 11, when a continued upward movement of the handle 31 moves the whole device with the shaft 20 about its axis against the spring 72, so that the part ba is formed. The shaft 20 is held in a bracket so that it can be adjusted vertically, horizontally and pivotally about an axis 2, not shown. Adjustment of the carriage 11 on the support 23 alters the ratio of the lengths of the arms of the lever 25 and thus varies the involute formed. Adjustment of the tool above or below the slider 27<SP>1</SP>, by vertical movement of the sitrrup 47 on a slideway 73 formed on the slider 27<SP>1</SP>, also varies the involute. The slider 26 may be made to roll on the quadrant 21 by means of straps, with the use of cams on the quadrant engaging an opening in the slider 26, or by a rack and pinion.