Patent GB-378937-A (GB)
Title: Improvements relating to cutting, setting and sharpening saws
IPC: B23D65/02
Filed: 1931-05-12
Abstract: 378,937. Cutting, setting, and sharpening saws. POEGGEL, E., 59A, Fichtenstrasse, Remscheid, Germany. May 12, 1931, No. 14081. Convention date, March 10. [Classes 83 (ii), 83 (iii), and 83 (iv).] In a combined machine for cutting, setting, and sharpening saws, means are provided for actuating the machine to cut a series of serrated lengths separated by blank portions, the lengths of the cut and uncut portions being selectively variable. The saw blank 11, Fig. 1, is fed intermittently through the machine by rollers 9, 10 rotated by a ratchet disc 8 which is actuated by a pawl 7 on a swinging arm 6. A link 5 connects the arm 6 to a crank pin 4 adjustable along a crank 2 which is rotated continuously from the main drive shaft 1 of the machine. The blank passes first to a punching machine 21 for forming the teeth and then to a setting-machine 23 and a sharpening-machine 24, the punching-machine being fixed to the bed 25 as close as possible to the feed rollers whilst the setting and sharpening machines are adjustable on the bed relatively thereto to suit the pitch of teeth being formed on the saw. A longitudinal shaft 20 is driven from the shaft 1 through bevel gears 16, 18 and a shaft 17, and carries, within the casing of each machine, an index plate 53, Fig. 2, provided with notches 52 corresponding in number to the velocity ratio of the shaft 20 to the shaft 1. In the example given there are three index notches and the velocity ratio is 1:3. The index plate 53, together with a gear 28, is attached to a sleeve rotatably mounted on the shaft 20 but capable of being driven thereby by a clutch, the gear 28 driving a transverse shaft 32 at the same speed as the shaft 1. An eccentric 33, Fig. 3, on the shaft 32 actuates a cutting-punch 35 for forming the saw teeth, spring hold-downs 37 being provided at each side of the punch. Two adjacent teeth are formed at each stroke and the punch cooperates with a fixed die 41, or alternatively a lower punch may be actuated by gearing 29a &c., each punch then cutting one tooth. The punches are interchangeable to produce the required shape of teeth. To maintain the punch idle whilst the saw is fed, in order to produce a blank head or uncut portion thereon, a cam disc 45 is driven by gearing 42, 43a .. 43i from the shaft 20 and co-operates with a roller 48 on an index plunger 49. The arrangement is such that the cam 45 rotates once whilst a saw length is being fed and when an untoothed portion thereon is required a gap 46 in the cam allows a spring 51 to engage the plunger with a notch 52 in the index plate 53, the plunger simultaneously throwing out the clutch for the plate and gear 28. When punching is again required, the cam 45 releases the plate 53 and allows the clutch to re-engage. The gap 46 in the cam corresponds to the length of the saw heads. In the setting- apparatus, upper and lower hammers 70, Fig. 4, are actuated by cams 64 on transverse shafts 63 driven from a gear 59 loose on the shaft 20 but integral with a sleeve carrying an index plate 53. The cams 64 have a lostmotion connection with the shafts 63 so that when rollers 67 on the hammer-slides 68 come opposite to radial portions of the cams, the latter may be rotated reversely so as not to impede the hammers when springs 69 drive the hammers inwards. Anvils 71 are provided opposite the hammers, both being interchangeable to suit the shape of saw teeth. To arrest the motion of the hammers when an untoothed portion of saw is presented, a cam 78 is driven by bevel gearing 82 from a shaft 14 connected by bevel gearing 13, Fig. 6, to the shaft 1 and acts on a roller 79 attached to a head 77 to which is secured a plunger 75. Each time the saw is fed the cam withdraws the plunger clear of the teeth and on again approaching the saw, by means of a spring 76, the plunger engages in the next tooth and causes the head 77 to act on the end of the index bolt 50, slidable therein, and withdraw the bolt clear of the index plate 53. When an untoothed portion of saw is presented, however, the plunger 75 is prevented from making its full forward stroke and the bolt 50 is free to move within the head 77 and enter a notch 52 in the plate, thereby throwing out the drive of the hammers and locking the plate against rotation. As soon as another tooth is presented the plunger 75 again moves further forwards and withdraws the bolt 50, thereby causing the hammers to be driven again. In the sharpening- apparatus, the rotary grinding or filing discs 92, Fig. 6, are carried by connecting rods 89 driven by cranks 88 rotated from the shaft 20 through gears 84, 85, the lower drive employing an idler gear 86. The rods 89 are guided by inclined slides 91 so as to cause the discs to follow a path 90 conforming to the shape of the teeth, that shown being for bow teeth. For " M " or frame-saw toothing &c. the guiding of the discs is modified. The actuation of the discs is prevented when an untoothed portion of the saw is presented, by a plunger 75 and index plate 53, similar to those shown in Fig. 4 for the setting hammers. When used for cutting &c. circular saws, the punching, setting and sharpening machines are arranged radially round a circular table to which the saw is secured, the feed being effected by indexing the table through a pawl and ratchet operated by an adjustable crank driven by the main shaft of the machine. A large bevel gear concentric with the table is rotated by the main shaft and serves to drive the separate machines through bevel pinions and radial shafts. The punching-machine is fixed to the machine bed which supports the table and the setting and sharpening machines are carried on an arcuate guide concentric with the table, an arcuate rack being provided on the guide for cooperating with pinions on the machine framings to enable adjustment to be made to suit the pitch of teeth on the saw. For curved saws the circular table is replaced by a segmental table, and the provision of means for preventing the operation of the setting and sharpening machines may be omitted when making circular saws.