Patent GB-1447215-A (GB)
Title: Machine tool for finish-grinding the inner surfaces of annular workpieces
IPC: B24B27/00
Filed: 1975-03-19
Abstract: 1447215 Grinding SOC NOUVELLE DE ROULEMENTS 19 March 1975 [8 April 1974] 11490/75 Heading B3D A machine tool for finish-grinding the inner surfaces of annular workpieces comprises a frame 1 carrying a support 4 for grinding wheel 38 and also supporting an axially movable table 7 which itself carries a rotatable support 26 for a workpiece 31, the table being pivoted on a single horizontal spindle 6 which also forms a guide for axial movement of the table and extends over a major part of the length of the tool, the spindle being situated in a substantially vertical plane containing the axis of rotation of the workpiece support and being mounted in a lower portion of the machine frame so as to maximise the distance between the axes of the spindle and workpiece support. The grinding wheel support 4 is mounted by an adjustment device 4a on a platform 2 on the frame, the device being provided for axial and lateral adjustment of the support which carries a spindle 3 for the grinding wheel belt driven from a motor 61. The lower part of the frame has a pair of bearings 5 supporting the spindle 6, the table 7 being mounted for axial and pivotable movement on the spindle by sleeves 8 and pre-stressed bearings protected by bellows 9. Axial movement of the table is effective by the supply of hydraulic fluid to a cylinder 11 carried by the table and co-operating with a piston 13 formed on the spindle. The pivotal movement of the table feeds the workpiece towards grinding wheel or compensates for wear of the grinding wheel and is controlled by a block 16 which is carried by a bar 17 on the table and engages a sloping surface 15a on a wedge 15 vertically movable by a ball jack 18 driven by gearing 19, 20 from a stepping motor 21, an hydraulic cylinder 22 holding the block against the wedge surface during grinding. A housing 25 on the upper part of the table 7 supports a hollow spindle 27 in roller bearings 27, the spindle being driven by a belt 29 from a motor 30 and having an electromagnetic coil 33 for holding the workpiece 31, such so the outer ring of a ball race, supported vertically by a shoe 34 pivoted to a pin 35 on a bracket 36. A further shoe 37 supports the workpiece laterally, the shoe being mounted on a pin 39 of a pneumatic advance controller, such as described in Specification 1,381,615, which initially advances the shoe to press the workpiece against the grinding wheel at a low force and then at a higher force for the grinding process proper. A sensor controls the lateral controller and position of the shoe 37 and contacts an eccentric stop 43 movable in a slot 44, the strip being rotated to give a sinusoidal advance followed by a spark. out. Workpieces are fed to the machine from a feed channel 45 and carried by a pivoted arm 46 to the grinding position, the advance of a new workpiece on the arm 46 engaging a roller 50 on a pivoted lever 51 to cause a pin 53 to eject a finished workpiece. The grinding wheel is dressed to the desired radius by a diamond 56 on a holder 58 carried by a C-spring 59 mounted on a spindle rotatable in a housing carried by a second C-spring 59a on a plate 55a pivoted between inoperative and operative positions. The C-springs are stressed by devices 59b, 59c to adjust the diamond to the radius of the race track and the radius of the toroidal profile. The machine may be arranged to grind an outer bearing ring having two tracks by providing two limit stops for the axial movement of the table 7. In another embodiment (Fig. 4, not shown) the machine finish grinds an inner cylindrical surface (70), the grinding wheel being axially reciprocated for a stroke of a few millimetres by a variable speed motor (67). In a further embodiment, the grinding wheel spindlcan be adjusted to produce a conical profile on the bore of the workpiece.