Patent GB-938006-A (GB)
Title: Improvements in or relating to machines for grinding elongate work-pieces
Inventor: PLUMMER HENRY JAMES
IPC: B24B19/14
Filed: 1959-05-01
Abstract: 938,006. Grinding and polishing. BRISTOL SIDDELEY ENGINES Ltd. May 2, 1960 [May 1, 1959], No. 14886/59. Class 60. A machine for grinding or polishing elongate workpieces, particularly those having curved surfaces such as compressor or turbine blades, of the kind having provision for relative reciprocation between a workpiece and a grinding head longitudinally of the workpiece and for incremental feeding relatively between the workpiece and the grinding head transversely of the workpiece, the reciprocation being controlled by limit switches operable by stops at the ends of the travel of the reciprocatable part of the machine, has at least one end stop in the form of a cam of which the profile is engageable by the corresponding limit switch, at different positions along the cam profile, corresponding to similar transverse positions on the workpiece, thereby to vary the stroke of reciprocation of the workpiece in accordance with the progressive application of transverse feed and thereby to copy the profile of the cam on the workpiece at at least one end thereof. A blade grinding machine, e.g. as in Specification 838,887, includes a table 1, Figs. 1, 2, arranged for reciprocation in the direction of the arrows 2. A belt grinding head 3 is mounted for vertical movement on a column 4 which also carries a ball-shaped follower 5. The workpiece and former are mounted longitudinally, in the direction of arrows 2, on the table 1 beneath the grinding head 3 and follower 5 respectively. Incremental feeding movement of the column 4 in the direction of arrow 6 is performed by a cross-feed lead screw 7 operated automatically or by hand wheel 8. The reciprocation of the table 1 is controlled by end stops 11 mounted on the table and engageable with non-reciprocatable limit switches located in a housing 9 mounted on a non- reciprocatable part 10 of the machine. The end stops 11 are constituted by the straight edges of angularly adjustable protractors 13 mounted on supports 12 adjustable longitudinally of the fable. The limit switches 14 are mounted on a carriage 15 arranged to be raised by a screwed column 16 mounted on the machine part 10 and geared to the lead screw 7 so that each time an increment of cross-feed is applied the screwed column 16 is rotated and the carriage 15 is raised by a corresponding amount, causing the stroke of the reciprocation to be varied in accordance with the angles to which the straight edges of the protractors 13 have been set. A blade having a shroud at the tip and a platform at the root end, may be ground. In a blade grinding machine, e.g. as in Specification 920,436, in which the workpiece and former are fixed and the grinding head and follower are reciprocatable longitudinally and are also arranged to be fed in increments in the transverse direction, the end stops are formed by protractors 17, Fig. 3, mounted on a rod 18 supported for longitudinal sliding in the direction of arrows 19 in accordance with the movement of the grinding head and follower. The rod 18 has a rack portion 30 engaged by a pinion 21 rotated with a drum 23 around which passes a belt 22 attached to a longitudinal slide carrying the grinding head and follower. To effect a reduction in the travel of the rod 18 compared with that of the longitudinal slide the diameter of the drum 23 is twice the pitch circle diameter of the pinion 21. Limit switches 27 engageable with the protractors 17 are mounted on a carriage 24 mounted on a saddle member 33 having an extension passing through a slot 31 in a column 25 and engaging a nut guided for vertical movement within the column. The nut threadedly engages a screwed rod 32 driven from a cross-feed lead screw through reduction gear so that vertical movement of the carriage 24 is one half the transverse movement of the grinding head and follower. The protractors 17 are mounted on supports 29 slidably adjustable along the rod 18. In the case of blades tapered in the longitudinal direction a sine-bar 26 is mounted on the supports 29 and can be adjustably inclined to the horizontal. The carriage 24 carries a further limit switch 28 arranged to engage the sine-bar 26 to reverse the reciprocatable part of the machine before the protractor 17 at one end of the travel can be engaged by the corresponding limit switch 27. A similar arrangement can be provided in the machine of Figs. 1, 2. Specification 793,366 also is referred to.