Patent GB-165641-A (GB)
Title: Machine for sharpening with a grindstone circular and band-saws
IPC: B23D63/12
Filed: 1920-05-29
Abstract: 165,641. Zanfranchi, J. T. lay 29, 1920. Saws, sharpening.-The saw s which may be a circular saw or a band saw, is held by a holder mounted on an upright c, and is sharpened by means of a grindstone i. The grindstone is journaled on a detachable spindle i<3> carried by an inclined carrier i<1>, which is adapted to be reciprocated on a slide l rocked about an axis k<2> under control of a camp, Fig. 4, having a profile corresponding to that of the saw teeth. The carrier i<1> is integral with a rod j slidably mounted in a sleeve k<1> formed on a carriage k, and the rod is adjustable axially by means of a screw j<1> and is guided by means of a scraw j<3> engaging a longitudinal groove j<4> in the rod; grooves j<5>, j<6> are also provided on the rod, one on each side of the groove j<4>, to allow of setting the grindstone for bevelled teeth. The carriage k is reciprocated on the slide l by means of a link l<1> engaging a crank-pin m adjustably mounted on a crank m<1> rotated through gearing n<1>, h<2> by a shaft h, and the slide is rocked about the axis k<2> by a lever o pivoted about the same axis and having one end o<2> in engagement with the slide and at the other end a roller o<1> in engagement with the cam p. The cam is mounted on the shaft h, which is driven through a belt by a hollow shaft q. When a band saw s is to be sharpened, this is held by a clasp comprising a plate c<1>, carried bv the upright c, and a frame d pivoted on an axis d<1> and pressed by weights d' or springs against the saw; the saw is supported by a blade e adjustably mounted on the frame d. The saw is fed forwards one tooth at a time by a push-rod f carried by a lever f<1> adapted to be oscillated about a pivot f<2> by a link engaging a crank-pin g<1> adjustably carried by a disc h<1> carried by the shaft h; the position of the rod is adjusted by a screw g<3>. Circular saws are mounted on a stud c<2> carried by the upright c, the frame d being removed. The grindstone is driven by a belt x passing over stretched pulleys x<1>, x<2> and a driving-pulley v<2>, which is driven by a belt from a pulley q<3> mounted on the shaft q. Loosely mounted on the shaft q is a main pulley r, Fig. 4, adapted to be clutched to the shaft by a claw-sleeve r<1> operated by a lever t, and inside the shaft q is mounted a short shaft u carrying a hand-wheel u<1>. The shaft u has thereon a tooth u<2> adapted to be engaged with a notch q<2> in the shaft q; the notch has an inclined side, whereby, on operation of the machine by power, the hand-wheel is automatically disengaged. In operation, the pulley r is unclutched and the machine is operated slowly by hand by means of the hand-wheel, the feed of the saw and the position of the rod f being set; the stroke of the carriage k is also adjusted. The adjustments may be verified owing to the slow movement of the parts produced by band-operation; the machine is then set in motion by power by operation of the lever t. In order to grind a saw having bevelled teeth, the alternate teeth having opposite bevels, the red j is rotated to bring one of the grooves j<3>, to engage the screw j<3> and the saw is fed forwards two teeth at each feed; when all the teeth having the same bevel have been ground, the rod j is rotated to bring the other groove to engage the screw j<3> and the remaining teeth are ground.