Patent GB-183587-A (GB)
Title: Improvements relating to driving chains
IPC: B21L9/00
Filed: 1921-04-27
Abstract: 183,587. Renold, Ltd., H., Herford, R. O., and Renshaw, A. April 27, 1921. Chains; rollers; bearings.- Bushes, rollers and the like for driving chains and other purposes are formed by bending a plain or profiled metal strip on a mandrel with rounded corners, and severing the best portion therefrom so as to obtain a blank of elongated U-shape, in order that when it is subsequently curved into cylindrical form, the ends thereof mav be of correct shape. Non-rotatable cylindrical or segmental chain bushes are made from a metal strip formed by rolling, drawing &c. to a section consisting of a central rib with flanges at the base, the back of the rib being arched so as to provide the necessary metal to form, during bending, a cylindrical or slightly barrel-shaped surface 33, Fig. 3, and the edges of the flanges being rounded to facilitate assembly in the links. After curving the surfaces are trued by a drifting operation. The reduced ends 35 formed from the flanges fit into the inner links and the outer links are secured by studs or rivets passing through the bushes. The bushes are preferably so arranged that the joint does not engage the teeth of the sprocket-wheel. The bushes or ordinary bushes may be used in conjunction with rotatable rollers, curved from a strip in the manner described. The first operation is performed by a pair of reciprocating dies 43, 44, Fig. 6, which, in the case of bushes of the form shown in Fig. 3, may be provided with projecting side plates to engage the flanges. The die 43 is carried by a slide 110, Fig. 20, which is actuated by a spring-pressed cian-operated lever 122 through a cross pin 126, which passes through a slot in the slide and through holes in a fork 127 sliding in grooves on a yoke 128 secured to the slide. The die 44 is carried by a slide 113 which is actuated by an eccentric 130 on a shaft 76, the strap 133 of which is connected by an adjustable slotted cross pin 135 to a lever 131, which carries a pin 138 passing through holes in a slidable fork 137 and througb a slot in the slide. The slides are cross-grooved for lubricating purposes. The strip 41 is fed by a reciprocating-gripper consisting cf two clamping levers 56, 57 and a feed lever 58 which are operated by cams on the shaft 85, Fig. 22. The feed lever is carried by a slide 68 provided with a roller 100 held in contact with a face cam 62 by an adjustable spring 101. The feed is adjusted by a screw stop 227. The strip is first bent as shown in Fig. 6 by the die 43 over a rectangular mandrel 42 with rounded corners. The die 44 then moves forward to bent the projecting end of the strip over the upper surface of the mandrel, the die 43 remaining in its raised position during part of this movement to prevent distortion at the previous bend. The die 43 then recedes and the bend is completed and the blank severed from the strip by a punch 45 which forces the scrap into a groove 46 in the mandrel. The mandrel may be reversed when worn or the worn end cut off. The blank 48 is then transferred on to a movable platform 49, Fig. 24, by a pusher 146 on a slide 142, which is normally drawn back by a spring 144 and which is operated by a lever 150 held by a spring 155, Fig. 19, in contact with a cam 149 on the shaft 76. The forward end of the pusher has a finger 147 which engages over the blank to prevent removal thereof by the die 44 in its receding movement, and is also provided with a projection 148 to eject the scrap from the groove in the mandrel. The curving is then performed round a mandrel 50 by a pair of reciprocating dies 52, Fig. 10, which may be formed with projecting side plates and are carried by slides provided with rack teeth in engagement with pinions on shafts driven by a double toothed rack bar linked to an eccentric rod on the shaft 76. The guide slot of the rack bar is provided at its upper end with a pivoted cover for lubricating purposes. The mandrel is seated in a recess in the platform 49, which is reciprocated by a cam on the shaft 76 through a spring-pressed lever 185, Fig. 22, connected by a rod 189 and elbow lever 190 to a block 192, which is secured to the platform by a screw 194. The mandrel passes through a hole in the forward end 196 of the tubular part of the platform and is connected b a screw 198 to an H-shaped slide 199, which bears against the side faces of a fixed block 200 and is normally held in contact with a recess 205 in a fixed table 193 by springs. The cam, which operates the platform, has two projections so that the platform is first withdrawn separately from the mandrel, after the blank has been clamped thereon, and then, after curving, takes the mandrel with it due to the block 192 engaging the slide 199. The blank is held on the mandrel during curving by a gripper 53 carried by a plunger 171, which is operated through a spring-pressed lever 173 connected to an adjustable rod 176, Fig. 19, which is linked to a sliding block engaging a cam 179 on the shaft 76 with two projections. In order that the dies 52 may finally close round the mandrel, the gripper may be temporarily lifted from the block, or the top of the jaws may be cut away from this purpose. During withdrawal of the mandrel the bush is stripped therefrom by a fixed block 51 and is impelled forward down the shoot 204 by a second movement of the gripper. The cam shaft 85 on which the cams for operating the feed grippers are mounted is connected by spur gear to a shaft 81, Fig. 19, which is driven by bevel gear from the cam shaft 76. The shaft 76 is driven from the main shaft 71 by spur gear 75, 74 through a clutch, the slidable member 72 of which is keyed to the shaft and is operated by a forked arm on a spindle 79 carrying a hand lever 80. In order that the machine may be set by hand prior to connecting the clutch, the spur wheel 75 may be, engaged by a pinion 93, which is carried by a bushed shaft 88 having a hand-wheel 87. This shaft is normally pressed outwards by a spring 91. In order to prevent the hand-wheel shaft from being brought into gear when the clutch is engaged and vice versa, this shaft has a boss 94 which engages a projection 95 on an arm carried by the spindle 79. The hand-lever is prevented from accidental displacement by a bevelled pin 97 engaging a bevelled spring stop 98. A number of bending and curving tools operating simultaneously or in succession over different arcs of the mandrels may be used in making the bush. The bushes.after bending and curving are transferred to another machine forshaping and polishing the surface thereof. The bush is placed on the reduced end of a plunger and is forced through a conical die.' According to the Provisional Specifications, bushes with reduced ends may be formed from tubular blanks by dies in a manner similar to the formation of heads on wire screws. It is also stated that the strip may be fed by intermittently driven rollers and severed by circular or band saws. Further, the initial step in forming a split bush may be performed by cutting a strip into lengths, and bending the ends of each blank simultaneously over the mandrel by a single curved reciprocating die. The curving operation may also be performed by a plunger engaging one end of the bent blank so as to force it into a cylindrical cavity containing a mandrel. In another form the bent blank may be curved by a reciprocating bending die having a curved recess which receives the blank and curves it over a mandrel. In a modification of this form the shape is completed by lateral dies. In a further form, the bent blank is forced by a punch into a curved recess in a die and the shape completed by a pair of laterally moving dies. In another form, curving is effected by a pair of sector-shaped dies. The split bushes may, in another form, be made by bending a continuous strip or cut blanks round a mandrel by a pneumatic hammer having a peening tool of required curved shape. The hammer may have a slight lateral movement round the mandrel so as to feed the blank automatically at each blow. Continuous lengths are cut at intervals in the feed channel by a punch. Completed bushes may be shaped to final form by a number of dies with curved ends, operated by cam surfaces in a manner similar to a screwing die, or by rolling on a mandrel by grooved rolls, or by straight or curved rolling dies one of which moves longitudinally over the other. The bush may be finished by rolling between a cylinder and a rotating boss having involute projections or ratchet teeth with rounded backs. The bushes for making chains may be fed to the assembling machine with their joints in alignment by providing a knife edge in the feed channel and feeding the bushes in contact with a rotating circular brush which brings the joints into alignment with the knife edge.