Patent GB-766759-A (GB)
Title: Machine for sharpening tools, chiefly blades of power mowers
IPC: B24B3/55
Filed: 1955-02-15
Abstract: 766,759. Sharpening tools, e.g. power mower blades. PHILIPPE, R. Feb. 15, 1955 [Feb. 15, 1954; Oct. 13, 1954], No. 4424/55. Class 60 A machine for sharpening tools particularly blades of power mowers, comprises two grinding wheels 4, 7 and a two-arm rocking beam 22 the opposite ends of which carry tool-holding means facing the corresponding grinding wheels. The grinding wheel 4, of natural material, e.g. sandstone, is mounted on a shaft 3 carried in bearings 2 on the machine frame 1; the hub 4<SP>1</SP> of the wheel is provided at its ends with notches engaging studs fitted on the shaft, the arrangement permitting lateral movement of the wheel to adjust itself to the notched mower blade. The grinding wheel 7, of artificial material, e.g. corundum, is mounted on a shaft 6 carried in bearings 5 on a frame 8 pivoted at 9 to the machine frame 1 and adjusted by a screw 10 The grinding wheel 4 is driven through gearing 16, 17 from an intermediate shaft driven through a belt 14 by an electric motor 12; the motor 12 is carried on a frame 11 pivoted at 9 to the machine frame 1 and adjusted by a screw 21 to tension the belt 21. The grinding wheel 7 is driven through a belt 19 by the intermediate shaft. The mower blades to be sharpened are carried on the ends of a beam 22 pivoted at 23 to the machine frame 1, the beam being oscillated by a connecting rod 26 secured at one end to a worm wheel 25 driven by a worm 24 on the grinding wheel shaft 3, and secured at the other end to a strap 27 adjustable in the beam by a screw 29 and locked in adjusted position by a wing nut 30. The attachment of the rod 26 to the worm wheel 25 may be adjustable, By replacing the bevelled grinding wheels 4, 7 by cylindrical grinding wheels and, if necessary, locking the beam 22 against movement, the machine may be used for sharpening other tools; a cylindrical grinding wheel 7<SP>1</SP> of artificial material may be mounted on the end of the shaft 6. In a modification, Fig. 4, the machine is hand operated. A hand crank 44 is mounted on a shaft 32 which drives the grinding wheel 4 through a chain 37. The shaft 32 drives the grinding wheel 7 through gearing in a casing 31, an intermediate shaft of the gearing carrying a cam 45 for oscillating the beam 22 which is pivoted at 23. The cam 45 acts on a lever 47 pivoted on the casing 31; a rod 48 passes through an opening in the free end of the lever 47 and carries a part spherical .washer 49 resting on the lever 47, the upper end of the rod 48 being threaded to receive a wing nut 50. The lower end of the rod 48 is secured to a bolt 38 engaging a slot 39 in a member 40 on the beam 22. The mower blade 76, Fig. 8, is clamped in a holder pivoted at 77 to a support 74 carried on a cross-bar 75 interconnecting the two arms of the rocking beam 22. The position of the blade 76 relative to the grinding wheel 4 is adjusted by a screw 79; a cam 71 pivoted at 72 to the support 74 co-operates with an adjustable stop 78 to move the tips of the blade away from the grinding wheel as the beam approaches its uppermost position. A removable arrangement for trueing the grinding wheels comprises, Fig. 7, a support 63 in which is journalled a rotary spindle 64 to which is keyed a support 65, one arm 65<SP>1</SP> of which has an adjusting screw 66 abutting at its inner end against a step-bearing on the support 63. Two carborundum blades are secured to the support 65 by straps 69; in the case of a grinding wheel with a cylindrical periphery a single block is used. The arrangement is mounted by screws with wing nuts 70 on the machine frame or on the rocking beam. The rocking beam may be acted on by springs or counterweights and rocked by hand.