Patent GB-1375352-A (GB)
IPC: B24B27/00
Filed: 1972-09-25
Abstract: 1375352 Grinding TRW Inc 25 Sept 1972 44271/72 Heading B3D A method of providing a plurality of locating surfaces 115, 116, 117, Figs. 3 and 4, on a workpiece 49, such as a blank for a turbine blade, comprises utilizing a machine having a plurality of grinding means 16, 17, 18, Figs. 1 and 2, with associated dress means 20, 21, 22 and positioning the workpiece with respect to the dress means, advancing a first grinding surface 48 across a first dress means 20 into the workpiece to dress the first grinding surface prior to contact with a workpiece to form a first location surface 115 thereon, retracting the first grinding surface and feeding it in a direction perpendicular to the grinding surface a predetermined amount, and repeating the process with a second grinding surface 48b to provide a second location surface 117 on the workpiece. The machine has a horizontal table 12 on which is an upstanding frame portion 15 having pivots 39, 39a for the grinding means 16, 17. The grinding means 16 has a wheel 27 with a flat surface 48 mounted on a shaft 28 which is mounted in a tubular shaft 29 axially movable by feed means 34 in a bearing 31, the shaft 28 being rotatable by a drive means 30. The grinding means 16 is carried by an arm 32 rigidly interconnected with a second arm 39 secured to an hydraulic cylinder 37, the rod 38 of which is adjustably connected to the frame portion 15. The grinding means 17 has a wheel 29a with a grinding surface 48a and is arranged in a similar fashion to the grinding means 16. When the cylinders 36, 36a are actuated, the grinding means 16, 17 are swung about their pivots 39, 39a so that the grinding surfaces 48, 48a first pass respective dressing blocks 20, 21 and then grind the surfaces 115, 116 on the workpiece 49. The grinding means 18 has a wheel 28b having a grinding surface 48b and a tubular shaft 29b slidable in a housing 40 by feed means 34b on an arm 42 pivotably movable in a bearing block 44 by an hydraulic cylinder so that the grinding surface 48b is first dressed by a block 22 and then grinds the surface 117 of the workpiece 49. As described, the machine has a work-holder 50 consisting of two parts 50a, 50b which are clamped together to hold three workpieces 49, 49a, 49b, each of which is to have locating surfaces 115, 116, 117 ground thereon. The work-holder is mounted on a lower support 53 and held against an upright surface 54 by a clamp 52. The supports 53, 54 are attached to a member 55 vertically movable on the frame portion 15. The member 55 has a rod 56 having spaced stops 57, 58 co-operating with an extension 59, and a rod 60 having trip means 61, 62 co-operating with limit switches 63, 64 controlling an hydraulic cylinder in actuating means 66 operative to raise the work-holder to sequentially position the workpieces 49, 49a, 49b for grinding by the grinding surfaces 48, 48a, 48b. In operation, the workpieces 49, 49a, 49b are clamped between the parts 50a, 50b of the workholder 50 which isheld against the surfaces 53,54 with the workpiece 49 positioned relative to the dressing means 20, 21, 22. The grinding means 16 is advanced by the cylinder 36 swinging the grinding means about the pivot 39 first at a rapid rate and then at a fine feed for the surface 48 of the wheel to be dressed by the block 20 and then to grind the locating surface 115. The grinding means is thereafter swung back to its initial position and the feed means 34 actuated to advance the wheel axially a small distance. The grinding means 17 is actuated in a similar manner to effect grinding of the locating surface 116 and then the grinding means 18 is actuated again in a similar manner for grinding the locating surface 117. Thereafter the actuating means 66 is operated to raise the work-holder 50 for grinding the locating surfaces on the workpiece 49a and then on the workpiece 49b. The grinding unit 16 may be adjusted so that the angle A, Fig. 4, between the locating surfaces 115, 117 is between 85 and 95 degrees. In another embodiment, the third grinding means is replaced by a drill.