GB860608A - Knife sharpener - Google Patents

Abstract

860,608. Knife sharpeners. SUNBEAM CORPORATION. Feb. 23, 1959 [Aug. 18, 1958], No. 6192/59. Class 60. A knife sharpener comprises two opposed motor-driven cupped grinding wheels 10, 11, the rim of the smaller wheel 10 fitting partially within that of the larger wheel, the wheels being disposed within a housing 15, having a knifegrinding slot 16 across the top thereof, on opposite sides of which the wheels 10, 11, are so mounted that their hollow portions are directed towards the top and rear of the housing, namely, the side opposite a thumb operated switch 75, Fig. 5, and the guide-dot 16 serves to limit contact between the knife-blade and the grinding wheels to rim portions rotating in a direction to grind the blade from cutting edge towards the back. The housing 15 is a moulding of plastic material with integral ribs 19, 20 and 23, 24 (not shown) for locating the grinding- wheel shaft bearing housings 12, 13 and the knife-blade respectively, when the latter is inserted within the slot 16. The drive is transmitted to the grinding wheels by moulded nylon bevel gears 52, 53 and pinions 49, 43 keyed to opposite ends of a motor shaft 41. The driving motor 14 is protected from abrasive dust by abutting portions 25, 26 of arcuate, inward extensions of the vertical partitioning members 12, 13 which form an enclosure for the wheels 10, 11, the motor being clamped between the members 12, 13. A base plate 46 is provided with vents 45, 47 to permit the intake and exhaust of cooling air circulated around the motor 14 by a fan 44 on the motor shaft, moulded feet 89 provide clearance below the base. The angle between the axis of each wheel shaft and the horizontal may be about 20 degrees and between the shafts and the vertical plane containing the motor shaft may be 3¢ degrees. The opposed rim-faces 10d, 11d of the wheels are slightly conical and the gear ratios are such as to provide equal linear speeds at the grinding faces. The switch 69, Fig. 5, is operated by a pivotally mounted plate 75 of insulating material which carries a boss 74 having mounted thereon L-shaped contact members 73, 77, the latter serving as a spring to bear the switch to the open position ; when pressed inwards the horizontal limbs of the contacts 73, 77 are brought together to complete the circuit between a lead 72 and the motor 14.