Patent GB-733569-A (GB)
Title: Improvements in or relating to saw sharpening machines
IPC: B23D63/12
Filed: 1953-02-19
Abstract: 733,569. Saw sharpening machines. VOLLMER, H., [trading as VOLLMER WERKE MASCHINENFABRIK GES.]. Feb. 19; 1953, No. 4706/53. Class 60. A saw sharpening machine, particularly for frame saws, is provided with mechanical and hydraulic means such that, after each mechanically-operated traverse of the work carriage 3, Fig. 2, the hydraulic means lift the grinding-wheel 13 and the feed-motion pawl 18, advance the grinding-wheel, reverse the carriage 3 and reengage the grinding-wheel with the saw blade 4. The carriage 3 is movable upon a guide 2 and provided with supports 5 and front and rear clamping jaws 7 for the blade 4 while the grinding-wheel 13 is rotated by a V-belt 14 from an electric motor 15 and mounted upon a carrier 12 vertically movable on the machine pedestal 1. The pawl 18 is pivotally connected with a rocking lever 19 and co-operates with the saw blade 4 and a control rail 8. A second electric motor (not shown) actuates the pawl 18 to move the saw blade from left to right in Fig. 2, moves the grinding-wheel in accordance with the tooth profile, and in the case of bevel grinding, pivots the grinding-wheel about a vertical axis after each tooth has been ground. During the sharpening operation, a pump 24, Fig. 4, circulates oil from a sump through pipes 26, 27 and a control valve 37. When the last tooth has been ground, this valve is rotated by a lever 34, Fig. 2, and a stop 11 to direct oil from the pump to a pipe 30 connected to a spring- loaded piston 46 which actuates a pawl and ratchet drive 47 for the grinding-wheel feed mechanism 16, a pipe 29 connected to a piston 41 to lift the grinding-wheel clear of the blade, and a pipe 48 connected to a spring-loaded piston 49 which actuates a pawl-and-ratchet drive for a cam disc 53. The latter, through a bell-crank lever 63, Fig. 5, controls a spring- loaded piston 38 controlling the oil flow to the pipes 29 and 30, and a switch 66 for the second electric motor. When the piston 41 has reached its highest position, oil flows through a pipe 31, Fig. 7, the valve 37 and a pipe 54 to a piston 56 which returns the carriage 3 to its initial position. Oil also flows through a pipe 57 to close a slide valve 39, Fig. 7, the flow to the pipe 31 being maintained by an additional spring-loaded valve 58 which is held open by the oil pressure until a stop 10 strikes the lever 34 to rotate the valve 37. The latter now connects the pipe 54 to a return pipe 28 and connects the pipes 26 and 27 to form a closed circuit with the sump so that the pressure in the pipe 29 is reduced and the valve 58 closed by its spring to hold the piston 41 in its raised position. Oil in the pipe 30 flows through a channel 67 to the pipe 27. The grinding-wheel and the feed pawl are lowered into engagement with the blade to start another traverse of the latter when a cam 62, driven by the mechanism for pivoting the grinding-wheel about a vertical axis, rocks a bell-crank lever 61 to open the valve 58. Repeated movements of the piston 46 eventually bring the lower end of the bell-crank lever 63, Fig. 5, into engagement with a reduced portion b of the cam disc 53 so that the valve 38 is displaced by its spring to close the entrance to the pipe 30 and further traverses of the blade are made without feed being applied to the grinding- wheel. Finally, a notch c engages the lever 63 and the valve 38 is further displaced to close the entrance to the pipe 29. At the same time, all three electric motors are switched off by the switch 66. The cam 53 is initially adjusted by hand in accordance with the number of traverses required and the portion b may be omitted. Hand controls are also provided for raising and lowering the grinding-wheel carrier 13, for adjusting the feed mechanism 16, and for switching on the electric motors.