Patent GB-391447-A (GB)
Title: Improvements in machines for grinding knife and like blades
IPC: B24B19/00
Filed: 1931-07-23
Abstract: 391,447. Grinding knife-blades &c. HAGUE, A. V., 9, Bosville Road, Crookes, Sheffield. July 23, 1931, No. 21022. [Class 60.] In a machine for the simultaneous grinding of a number of knife, scissor, or like blades, the blades 200, moved simultaneously in a direction substantially radial to the annular grinding wheel 1, are ground during a single outward radial movement and are withdrawn from the wheel during the return inward movement. The grinding wheel is mounted on a vertical shaft 2 driven by a pulley 3 and carried in bearings on a sleeve 6. An outer sleeve 7 movable axially over the sleeve 6 carries a central hub 8 fitted with a number of piston rods 9 carrying pistons 10 which slide in movable cylinders 11 spaced around the axis of the shaft 2. The cylinders are provided with racks 13 engaged by pinions 14 carried on shafts 15 mounted in extensions of the sleeve 7. All the shafts 15 are connected together by universal joints 18 so that all the cylinders are constrained to move simultaneously. Outward movement of each cylinder is limited by an adjustable pin-stop 19 on the pinion 14 coacting with an abutment 20. Adjustable strips 22 are mounted at opposite sides of each cylinder, one engaging a spring-mounted roller 26 and the other a fixed roller. By adjustment of the strips a slight rotary movement is imparted to the cylinders and the knives 200 mounted thereon to produce the required thickening of the backs of the knife blades towards the bolster ends. In order to move the sleeve 7 with the knife carriers upwards towards the grinding wheel, the sleeve is fitted with a screwed spindle 33 which is movable longitudinally by means of a nut operated by worm gearing 39 and which carries a roller 35 engaging a wedge element 40 carried by the piston rod 41 of a hydraulic cylinder 43. Initial adjustment of the cut and adjustment to take up wear of the wheel is effected by the worm gearing 39 while automatic movement of the work-holders to and from the grinding-wheel for the cutting and idle strokes is effected by movement of the wedge element 40. A sprocket 44 connected to one of the wheels 14 is connected by a chain 45 to a wheel 46 which carries abutments 98, 104 controlling through a lever 99 the operation of piston valves V<1>, V<2>. An extension of the wedge element 40 carries pins 50, 51 controlling through a lever 49 the piston valve 56 of a valve assembly V<3> and a third pin 52 coacts with a lever 53 operating through pawl- and-ratchet mechanism 73, 70 a cam 69 controlling a piston valve element 68. The hydraulic fluid is supplied by a pump 5 driven from a pulley 4 on the grinding-wheel spindle, the pump delivery passing to the cut-off valve element 68 through a port 55. From this valve element the fluid passes to the element 56 which controls admission to the cylinders 10. The port 85 leads through a line 57 to a header 61 communicating with the front sides of all the pistons 10. Similarly the port 84 leads through a line 62 to a header 63 communicating with the rear sides of all the pistons 10. Branches from the lines 57, 62 communicate respectively with the piston valves V<1>, V<2> controlling the flow to the cylinder 43. The blade carriers 103 are each secured to a spindle 106 bearing in a sleeve secured in a bracket extension 109 of the cylinder 11. A collar 110 on the sleeve is secured to a casing containing a hydraulic cylinder 67 and the collar is also secured to a dog clutch ring 113 provided with cam surfaces 114. A ratchet ring 116 fixed on the spindle 106 carries the complementary clutch member and coacts with a three-armed spider 118 loose on the spindle 106. One arm of the spider carries a pawl 122 and a toothed segment 127 forming part of the spideris engaged by teeth on the piston 128. The cylinder 67 is supplied from a port 66 in the cylinder 11. The blade-holder carries a number of blades, for instance nine, the point being supported against a stop 140, Fig. 3, and the tang being held in a V-block 135 by a spring- pressed lever 134. On completion of the grinding operation a cam lever 143 is turned inwards against a stop 145 so that as the bladecarrier is rotated by hand, after the grinding of all the blades has been completed, a roller 137 on each lever 134 is forced inwards by the arm 143 whereupon the blade tang is lifted by a spring 142 and the blades removed and replaced by fresh work-pieces. The number of teeth on the wheel 116 is the same as the number of work-pieces. When the cylinders 11 are moving inwards on the idle stroke the piston 128 is moved against the spring 130. This movement first causes fingers pivoted on the spider to travel along the cams 114 causing the dog-clutch to be disengaged. Further movement of the piston 128 causes the pawl 122 to rotate the ratchet wheel 116 and bring a fresh blade into position for grinding. During the outward or working movement of the cylinders 11 the blades are raised into contact with the grinding wheel by actuation of the piston 43. The speed of the idle stroke is roughly twice that of the working stroke, due to the difference between the front and rear areas of the pistons 10. After a predetermined number of operations, equal to the number of blades on each carrier, the cam 69 is brought by its ratchet mechanism into a position wherein the valve piston 68 slips off the projection 77 and the valve 68 is moved by a spring into a position wherein the pressure fluid is byepassed back to the sump thus bringing the cylinders to rest. In a modification the cylinders may all be connected to a scroll arranged so that they are moved simultaneously to and from the grinding wheel, or, in another modification, the cylinders 11 may be reciprocated by direct drive from the axles 15. Also the withdrawal and return movements may be imparted to the grinding wheel instead of to the blade carriers. In another modification, Fig. 6, the axially movable outer sleeve 7<1> carries a number of piston rods 9<1> over which slide reciprocating cylinders 11<1> carrying holders for blades 200<1>. The axial movements of the sleeve 71 to move the blades to and from the grinding wheel at the required times in the cycle may be effected by a bell-crank lever operated by a fluidpressure cylinder. In this form a hand-controlled two-way valve is provided for first directing fluid to one set of alternate cylinders and then to the second set of cylinders. While the blades on one set of carriers are being ground the remaining carriers are at rest and the blades thereon are changed.