Conveyor drive chains

Abstract: Conveyor drive chain (24) for an accumulator roller conveyor. The endless chain (24) includes standard roller chain links (166) retained between side plates (168,170). Plastic drive pads (172) are snapped into locking engagement with side plates (168,170). The pads (172) contact the rollers (18) and imparts rotational force thereto (18).

Description: This invention relates to drive chains, particularly for endless belts. In so-called 'accumulation conveyors' consisting of a series of load-bearing rollers, the rollers may be selectively rotated, so as to transfer goods resting on the rollers, by selectively pressing into contact with them incremental lengths of continuously-driven drive chain. The drive chain of this invention is of the roller chain type, in that it has links consisting of rollers and side plates, the rollers being mounted for rotation on pins which connect the side plates. A drive chain of this type is described in US-A-5 042 244. In the roller chain of this invention, pairs of short side plates alternate with pairs of long side plates, and the long side plates are adapted to carry pads intended to rotate superposed rollers by being brought into frictional contact with them when the respective length of moving chain is urged upwardly. EP-A-0 068 886 (Lear Siegler) discloses a drive chain in which the links are all of the same pitch, and in which each link has a drive transmission element secured to it. Each element has projecting from its rear face a split-ended tongue of resilient material which extends between a pair of adjacent rollers to engage them resiliently to hold the element in place. This chain suffers from the disadvantage that, should the chain become misregistered with the teeth of the sprocket wheel which drives the chain, the teeth can push the tongues out of engagement with the rollers, and thus cause the elements to fall from the chain. The endless drive chain fitted with drive pads of this invention represents a marked improvement over known endless chains, and is as claimed in the appended claims. More specifically, it incorporates a series of standard-pitch roller chain links coupled together by pairs of longer side plates, which are configured to receive plastics drive pads that clip into recesses in the side plates. Each drive pad segment is a parallelogram in plan. The belt configuration permits the belt to pass around sprocket wheels at opposite ends of the conveyor without jamming and without there being any possibility that the sprocket teeth may come into contact with any part of the pads. When the chain is biassed upwardly, the drive pads contact the undersides of the rollers for driving them without slippage. The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a length of the drive chain of the present invention for use with an accumulating conveyor; Figure 2 is a top plan view of the length of drive chain of Fig. 1 over a fragment of the drive sprocket; Figure 3 is a vertical, cross-sectional, view of the drive chain and a fragment of the drive sprocket about which the drive chain passes, such view being taken along line III-III in Fig. 2 and in the direction indicated; Figure 4 is a side elevational view of a few links in the drive chain; Figure 5 is a vertical, cross-sectional view of the drive chain, such view being taken along line V-V in Fig. 4 and in the direction indicated; Figure 6 is a top plan view of the fragment of drive chain shown in Fig. 5, and Figure 7 is a bottom plan view of a pad that is engaged with the roller links of the drive chain. An endless drive chain 24 extends along the length of conveyor 10. A first upwardly-opening extrusion 26 receives the lower run of chain 24, while a second upwardly-opening extrusion 28 receives the upper run of endless chain 24. One leg of U-shaped control channel 30 is secured to channel 12 by bolts or other fasteners, while the base of channel 30 is secured to spreader 16 by fastening clip 32. A bolt 34 and nut 36 retains the clip 32 in fixed position, and a retainer 38 maintains the extrusion 26 in fixed position. Fig. 1 depicts a length of endless chain 24 that selectively contacts rollers 18, and, when in contact, imparts force thereto to rotate them. Endless chain 24 includes standard-pitch roller chain links 166 coupled together by means of double-pitch side plates 168, 170. Plastics drive pads 172 are snapped into latching engagement with side plates 168, 170. Some of the drive pads 172 in Fig. 1 are shown positioned above the side plates 168, 170, prior to being seated thereon. The parallelogram shape of drive pads 172, when viewed from above, is shown in Figs. 2 and 6. Each pin 174 extends transversely through longer side plates 168, 170, standard-pitch side plates 166, and rollers (not referenced), so that the rollers may rotate relative to the side plates. Notches 176, 180 are formed in the edge faces of side plates 168, 170 and slots 178, 182 are formed in the side plates below the notches, in vertical alignment. The edge faces of the side plates are substantially planar to provide additional support for the drive pads. Fig. 2 shows that each drive pad 172, because of its parallelogram configuration, has its ends extending beyond the ends of the longer side plates 168, 170. At least the apex of the pad extends a small distance over the adjacent standard-pitch links in the endless chain; such shape reduces the chatter usually associated with rectangular drive pads on padded chains, and also ensures that contact with the rollers 18 can be maintained, at all times, when the rollers 18 are driven by the drive chain 24. Parallel grooves 184 are formed in the drive surface of each drive pad 172 to enhance the frictional contact and effectiveness of the pads 172 when such pads are engaged with rollers 18. As can be seen from Figs. 2 and 6, each pad is spaced axially from its neighbour by a gap of constant width, to ensure that the pads never come into contact with each other once in place. It can also be seen that each pad is wider than the maximum width of the chain itself, to increase the contact area between each pad and the transport rollers. Fig. 3 shows the manner in which endless chain 24 engages the drive sprocket 186. The teeth 188 on the drive sprocket project upwardly between side plates 168, 170, and the roller links 166 fit into the valleys formed between adjacent teeth 188, so that the chain conforms to the curvature of the sprocket. An electrical motor 190 rotates drive sprocket 186 to deliver rotational forces to rollers 18, when the drive chain is elevated into contact with the rollers. A gear reducer (not shown) may be interposed between motor 190 and the shaft upon which the sprocket is secured. Drive sprocket 186 is located at the inlet, or head end, of the accumulating conveyor. A similar sprocket (not shown) is located at the tail, or discharge end, of the conveyor; thus, the endless chain 24 extends the length of the conveyor in an upper run, and a lower, parallel, run. Figs. 4-6 show the manner in which each drive pad 172 is latched into engagement with the side plates 168, 170 of the endless chain 24, while Fig. 7 shows the underside of a drive pad 172. Each drive pad 172 is a unitary molded plastics component, including a planar drive surface with grooves 184, and a pair of tongues 192, 194 spaced inwardly from the sides of the drive pad and projecting from the remote face of the pad. Tongues 192, 194 fit between side plates 168, 170, and the lower ends of the tongues have outwardly-projecting lugs 196, 198. A first projection 200 is formed adjacent one side of drive pad 172, and a second, identical projection 202 is formed adjacent the other side. Pairs of arcuate saddles 204, 206 project from the same remote face of the drive pad, while pairs of arcuate saddles 208, 210 are formed near the other end of the drive pad. In order to secure each drive pad 172 to the chain, it is pressed downwardly into seating engagement with the side plates 168, 170 of the endless chain 24. In so doing, the tongues 192, 194 move downwardly until projecting lugs 196, 198 flex outwardly into slots 178, 182; projections 200, 202 fit into notches 176, 180 in the side plates, and saddles 204, 206 and 208, 210 fit about the rollers retained between the side plates 168, 170. The tongues, lugs, projections, seats, etc. are molded within close tolerances so that the drive links can readily be snapped into engagement with the endless chain, and can be removed therefrom, for replacement as necessary. Accordingly it will be seen that the present invention provides a drive chain fitted with drive pads, which chain is relatively quiet in operation, and in which the drive pads are not able to come into contact either with each other or with the sprocket teeth driving the chain.

Claims: A roller chain (24) for use in a conveyor, the chain comprising: links consisting of pairs of parallel side plates (168, 170) connected together, and spaced apart from each other, by pairs of pins (174) encircled by rollers (166), with adjacent side plates being of different lengths, so that short (166) and long (168, 170) side plates alternate along the length of the chain; a slot (178, 182) formed in each long side plate between the respective rollers; a molded plastics drive pad (172) presenting a planar contact surface, and having a pair of tongues (192, 194), and a pair of projections (200, 202), projecting from the opposite face of the pad, with projecting lugs (196, 198) extending laterally outwardly from the ends of the tongues; the drive pad being seated on each pair of long side plates and being retained in position by the tongues (192, 194) extending into the space between the side plates with the lugs (196, 198) engaged in the slots (178, 182), and with the projections (200, 202) being seated in corresponding recesses (176, 180) in the respective edge faces of the side plates. A chain as claimed in claim 1, wherein pairs of arcuate saddles (204, 206) project from the underside of each drive pad, the saddles being intended to contact the rollers when the drive pad is in place on the side plates. A roller chain as claimed in claim 1 or 2, in which each drive pad has its ends extending beyond the ends of the respective side plates. A roller chain as claimed in any preceding claim, in which the shape of each drive pad is a parallelogram in plan, in which the pads are spaced apart longitudinally by a gap of substantially uniform width, and in which the apex at each end of each pad overlaps longitudinally the apex at the respective end of the adjacent pad. A roller chain as claimed in any preceding claim, in which the two major faces of each pad are parallel to each other and are coextensive. A roller chain as claimed in any preceding claim, in which the width of each drive pad (172), perpendicular to the width of the chain, is equal to or greater than the distance between the outside faces of the side plates. A roller chain as claimed in any preceding claim, in which the length of the long side plates (168, 170) is twice the length of the short side plates (166).

Inventors: HEIT MARTIN A, RAU WILLIAM C, WILKINS JOHN J, HEIT, MARTIN A., RAU, WILLIAM C., WILKINS, JOHN J.
Applicants: HK SYSTEMS INC, HK SYSTEMS, INC.
Application year: 1992
Main classification: B65G13
IPC codes: B65G47, B65G17