| 摘要 |
962,894. Grinding. BRYANT CHUCKING. GRINDER CO. April 1, 1963 [April 6, 1962], No. 12761/63. Heading B3D. A precision indexing device for a grinding machine comprises a table 22 which is mounted for rotational and axial movement in a housing 46 and has a pair of precision locating members 37 engageable with a pair of locating surfaces 55 on the housing. The locating members are formed by cylindrical surfaces at the end of a bar 36 secured by screws 39 to the table and extending through a bore 35 in the table, the bore intersecting the axis of rotation of the table. The locating surfaces 55 are formed at diametrically opposed positions on the housing and have a concave shape complementary to that of the members 37. A pair of guard projections 42 are located on the table on an axis at 90 degrees to that of the bar 36, and the housing has a pair of recesses 54 which are also at 90 degrees to the axis containing the locating surfaces 55 and are somewhat deeper than those surfaces so that, in certain relative positions of the table and housing, the members 37 are received with clearance in the recesses at the same time as the guard projections are received in a groove 56 in the precision locating surfaces 55. The device may be used in a grinding operation in which workpieces 23, 24, Fig. 7, are mounted on the table for successive grinding of surfaces 25, 26 by grinding wheels 27, 28 between unloading and loading positions. In the loading and unloading positions, the undersurface 38, Fig. 9, of the table rests on the housing with the members 37 spaced from the surfaces 59 of the recesses and the guard projections located in the grooves 56 in the locating surfaces, and in the grinding positions of the table, the surface 38, Fig. 5, is spaced from the housing by the engagement of the locating members 37 with the precision surfaces 55. The surfaces 55 and 38 have grooves 57, 58, Fig. 11, to prevent damage to the surfaces by the guard projections. The table is guided for axial and rotational movement relative to the housing by bearings 66, 67 between a depending portion 34 of the table and an extension 49 of the housing. The portion 34 has relieved portions 75, 76, Fig. 2, in the region of the bearing 66 to permit limited relative movement of this portion and table in a direction transverse to an axis 74 which is parallel to the axis of the bar 36, and has relieved portions at 90 degrees to the portions 75, 76 in the region of the bearing 67 to permit limited movement of the lower end of the portion 34 in the direction of the axis of the bar 36 to ensure accurate seating of the members 37 on the surfaces 55. The axial and rotational indexing movements of the table may be effected by electric or hydraulic means. A cover 33 surrounds the table, and a source of low pressure filtered air is supplied to a passage 63 to prevent the creation of a vacuum and the drawing of dirt into the device as the table is lifted. |
