Patent GB-203823-A (GB)
Title: Machine for grinding saw teeth and the like
IPC: B23D63/12
Filed: 1922-06-30
Abstract: 203,823. Bolinders Mekaniska Verkstads Aktiebolag, J. & C. G., and Lifflander, J. O. June 30, 1922. Saws and like tools, sharpening.-In a machine for grinding the teeth of saws &c. having means for producing relative movement between the grinding-disc and the saw and means for feeding forward the saw, the means for producing relative movement and the means for feeding are driven through a device which may be adjusted during operatior. of the machine and is so arranged that in all positions of adjustment the movements of the aforesaid means each start from a respective position common to all such movements and maintain a constant proportion. The machine comprises a base 1 in which is mounted a driving-shaft having at one end a single-threaded worm 4 and at the other end a double-threaded worm 5. The worm 4 drives a worm-wheel 6 mounted on a shaft 7 running in bearings 9 in which is also journaled a support 10. The support 10 carries at its outer end a frame 14, which carries a grinding-disc 21 and is supported by a shaft 13 in bearings 12 on the support, the frame being adjustable up and down by a screw 15. Secured to the frame is a toothed segment 23 engaged by a rack 24, which is pivoted at 27 to, and is reciprocated to rotate the grinding-disc for producing the bevel cut, by a lever 28 having at its lower end a roller 29 engaging a cam 30 on the shaft 7. The stroke of the rack is varied or suppressed by vertical adjustment of a slide 33 on which is pivoted a yoke 31 carrying rollers 34 bearing one against each side of the lever 28 and pressed against the lever by a spring 35. The up and down movement of the support 10 and the feed of the saw are obtained from cams 50, 51, Fig. 4, driven by a shaft 46 rotated, at twice the speed of the shaft 7, by a worm-wheel 41 engaging the worm 5. The shaft 46 is telescopic and runs at one end in a bearing 43 on the frame 1 and at other end in a bearing in a slide 44 movable horizontally in guides in the frame by a screw 47. The cams 50, 51 engage, respectively, rollers on levers 54, 55 pivoted on slide 44; the lever 54 is engaged by a roller 56 carried by the support 10, whereby this is raised and lowered, and the lever 55 engages a roller 58 carried by a link 59 which actuates a shaft 63 carrying the feed-pawl 88. The cams 50, 51 are so shaped that when their highest points engage the levers 54, 55 the operating sides of those levers are horizontal; adjustment of the slide 44 therefore varies the movement of the rollers 56, 58 proportionally. The shaft 63 is journaled in a bearing 64 secured to a slide-support 65, which is mounted, by means of a hollow trunnion 66, in the bed 1, whereby it may be adjusted angularly. On the support is a slide 68 movable up and down by a screw 69 operated by a hand wheel 92, and on the slide is a stud 75 upon which the saw is secured by a washer 76 and nut 77. The periphery of the saw is held, during grinding, against an abutment 78 by means of a presser 79, which may be retracted against the pressure of a spring, by a crank 82 screwing on the presser. The trunnion is hollow to allow a suction conduit to be applied thereto to remove dust. In operation, when a rip saw is to be ground, the front edge of a tooth is adjusted to be vertical and the slide 33 is adjusted so that there is no rotary movement of the frame 14. The grinding-disc, operating with its edge only on account of its inclined position, moves downwards and grinds the straight face of tooth. The saw is then fed forwards by the pawl, the back of the tooth being ground during the feed by the upward movement of the grinding-disc. If the feed is to be changed for a different pitch, the slide 44 is adjusted as described above. When grinding cross-cutting saws, the slide 33 is adjusted to give the rotary movement of frame 14 to produce the required bevel cut.