Abstract:
A conveyor chain formed of parallel links with pins extending laterally therefrom has pads mounted to the pins. Each pad has an elongated planar upper surface extending further than the distance between adjacent pins on the links. A notch on each end of the pad enables adjacent pads to overlap each other, and the shape of a notch and location of apertures in the pad enables the upper surfaces to define a substantially continuous contact surface when adjacent chain links are not wrapped, and enable the chain to engage a drive sprocket regardless of the direction of wrap.

Description:
RELATED APPLICATION 
     This application is a continuation of PCT International Application Number PCT/US00/02178, filed Jan. 28, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to conveyors and drive mechanisms for conveyors, and more particularly to a padded chain for conveying articles or driving rollers in a conveying system such as an accumulation conveyor. 
     2. Related Art 
     Over the yeas, various combinations of chain and rubber or plastic pads or belts have been devised and used to drive the rollers in a roller conveyor. These devices include a chain drive wherein a pad or high friction member is a continuous band, similar to a belt, mounted to the chain links wherein the links are positioned horizontally with respect to the conveyor rollers as in U.S. Pat. No. 5,176,246 to Wiggers et al. They also include devices where an elastic belt is mounted to a chain wherein the chain rollers are parallel to the rollers of a conveyor as in U.S. Pat. No. 4,074,085 to Bodewes. It is also known to use individual pads, one of which is mounted on each link of the chain as disclosed, for example, in U.S. Pat. No. 4,458,809 to White et al., and U.S. Pat. No. 5,906,267 to Heit et al. 
     One of the limitations of devices such as the horizontal continuous belt of the Wiggers et al. patent or roller mounted pads as in the Bodewes and White et al. patents is that the chain is incapable of a reverse wrap. Consequently, the drive chain can only effectively move the rollers in a single direction. 
     A known solution to the “reverse wrap” problem is found in padded chains wherein individual pads are mounted exterior of and parallel to the links. An example of this construction is shown in FIGS. 1 and 2, illustrating a padded conveyor drive chain  60  manufactured by Rapid Industries. The drive chain  60  comprises a plurality of interconnected conventional links  62 . An elastomeric pad  64  is mounted on each side of the chain  60  on consecutive links  62  by pins  66  extending laterally through the links  62 , securing the pads  64  by an external link-shaped washer  68 . Each pad  64  is roughly trapezoidal shaped, thereby enabling the chain  60  to wrap in both directions. 
     One of the limitations of the padded chain of FIGS. 1 and 2 is that spaces exist between the respective pads  64 , generating significant noise and uneven motion as the chain  60  interacts with the rollers  50  as part of the chain conveyor  10 ,  12 ,  14 . They also may not provide adequate “gripping” if the chain were to be used as a conveyor itself, moving articles requiring special handling such as furniture or appliances. 
     These and other limitations of known padded chain conveyors remain significant problems in the industry. 
     SUMMARY OF THE INVENTION 
     A padded chain according to the invention is particularly suited to function as a propelling member for articles or for another conveyor, and finds application especially practical for accumulation conveyors. The propelling member typically comprises a roller chain of the type having pins extending laterally therefrom. A plurality of high friction pads is secured to the laterally extending pins. Each pad has an elongated upper surface, longer than the distance between two adjacent pins, and a cutout portion at each end of the pad. Each cutout portion defines an inside face that overlaps the inside face of an adjacent pad so that the roller chain can be reverse-wrapped around a sprocket, and the upper surface will maintain a substantially continuous contact surface regardless of the direction of wrap. 
     Other objects, features, and advantages of the invention will be apparent from the ensuing description in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 depicts a prior art padded chain; 
     FIG. 2 is a cross-sectional view through line  2 — 2  of the padded chain of FIG. 1; 
     FIG. 3 is a side view of a padded conveyor chain according to the invention; 
     FIG. 4 is a plan view of the padded conveyor chain of FIG. 3; 
     FIG. 5 is a cross-sectional view taken through line  5 — 5  of FIG. 4, 
     FIG. 6 is a cross-sectional view taken through line  6 — 6  of FIG. 5; 
     FIG. 7 is a cross-sectional view taken through line  7 — 7  of FIG. 6; 
     FIG. 8 is an enlarged side view of a chain pad of the padded conveyor chain of FIGS. 3-7; 
     FIG. 9 is an enlarged plan view of a chain pad of the padded conveyor chain of FIGS. 3-8; 
     FIG. 10 is an enlarged side view of two interacting chain pads of the padded conveyor chain of FIGS. 3-11; 
     FIG. 11 is an enlarged side view of an alternative embodiment of a chain pad of the padded conveyor chain allowing even tighter reverse wrapping according to the invention; 
     FIG. 12 is a partial side view of a padded chain according to the invention wrapping around a sprocket; and 
     FIG. 13 is a partial side view of a padded chain according to the invention reverse wrapping around a sprocket. 
     FIGS. 14-16 depict the environment of driven conveyor systems that are enabled by the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Looking now to FIGS. 3-7, a padded drive chain  90  according to the invention is shown, comprising a steel chain  100  to which are affixed a plurality of chain pads  200 . The steel chain  100  is conventional in that it comprises of a number of pairs of inner links  110 , each link pair being joined by a pair of sleeves  116  and each pair of inner links  110  being connected to an adjacent pair of inner links  110  by a pair of outer links  120  with hollow rollers  126  extending through the sleeves  116  to conjoin the pairs of outer links  120 . Thus, each pair of inner links  110  is free to rotate in two directions relative to the joined pair of outer links  120 . 
     Chain pads  200  according to the invention as described below are adapted to be mounted to the outer links  120 . An elongated pin  132 , sized to rotatably mount within each hollow roller  126 , extends through each roller  126  on both sides of the chain  100 . On one side of the chain, two pins  132  are connected to each other in a parallel relationship by a fixed pin connector or fixed side link  134 . The fixed pin connector  134  is, but need not be, shaped congruently with the outer link  120  with which it is parallel. The connector  134  is secured to the pins  132  by any well known fastening relationship, e.g., riveting the ends of the pins. A chain pad  200  is mounted to the pins between the fixed pin connector  134  and the outer link  120  on one side of the chain  100 . The end of each pin  132  opposite the fixed pin connector  134  comprises an annular groove  133 . A removable pin connector or removable bide link  136 , typically shaped congruently relative to a fixed pin connector  134  or an outer link  120 , is received over the pins  132  and retained thereon by a spring clip or snap washer  138  adapted to clip onto the pins  132  in cooperation with the annular grooves  133 . Another chain pad  200  is mounted to the pins  32  between the removable pin Connector  136  and the outer link  120  on the other side of the chain  100 . 
     Referring now in particular to FIGS. 8-10, the chain pad  200  is generally trapezoidal in side view, having a generally flat top surface  210 , a generally flat bottom surface  220 , and two truncated ends  230 . Referring specifically to FIG. 9, which is a plan view of the chain pad  200 , the chain pad has an inside face  240  and an. outside face  250  substantially parallel to each other. The inside and outside faces  240 ,  250  are substantially identical mirror images of each other. The chain pad  200  has a pair of apertures  260  passing therethrough, each of the apertures  260  opening to the inside face  240  and further comprising an annular recess  262  around it. The recess  262  accommodates any lip on the rollers  124  to which the outer links  120  are connected so that the inside surface  240  of the chain pad  200  can filly abut the adjacent outer link  120  when it is mounted on the pin  132 . Each of the inside and outside faces  240 ,  250  have at one end thereof a cutout  270  forming a sloped shoulder  275  and a side face  277 . Each side face  277  is substantially parallel with the opposite respective inside or outside face  240 ,  250 . It will be apparent in FIG. 10 that adjacent chain pads  200  overlap where side faces  277  on adjacent pads actually face each S other. In other words, the cutouts  270  provide a space whereby corresponding ends  230  of adjacent chain pads  200  can nest in close relationship with each other, yet the top surface  210  remains essentially contiguous along the length of the chain. Each of the projecting ends  230  of the chain pad  200  preferably has a chamfered edge  280  between the end  230  and the side face  277  in order to minimize any tendency for adjacent ands to abut as the chain  100  wraps around a sprocket as explained more fully below. 
     An alternative embodiment of the chain pad according to the invention is disclosed in FIG. 11, wherein a chain pad  300  has a generally concave cutout  370  rather than the straight cutout  270  of the first embodiment. The resulting shoulder  375  is arcuate, and preferably, the end wall  330  is also curved rather than being truncated in order to better nest within an adjacent cutout  370 . A curved top edge  390  is also provided at each end of the pad  300 . The principal benefit of this embodiments is that a tighter reverse wrap can be obtained as explained below, while still maintaining a substantially contiguous top surface  310 . 
     ASSEMBLY 
     The steel chain  100  will generally come as a pre-assembled unit. To this assembled steel chain  100  will be attached the chain pads  200 . 
     The assembly comprising a pair of pins  132  and the fixed pin connector (fixed side link)  134  receive a chain pad  200  with the outside face  250  of the chain pad abutting the side link  134  and the pins extending from the inside face  240 . The pins  132  are then inserted into two adjacent hollow rollers  126  connecting the outer links  120  until the inside face  240  of the chain pad  200  abuts the outer link  120 . Any lip of the hollow roller  126  extending beyond the outer link  120  nests within the annular recess  262  surrounding the aperture  260  on the inside face  240  of the chain pad  200 . A second chain pad  200  is then placed over the protruding pins  132  until any raged lip of the opposing hollow roller  126  nests in the annular recess  262  surrounding the respective apertures  260  on the inside face  240  of the second chain pad  200  and the inside face  240  fully abuts the second outer link  120 . The removable pin connector (removable side link)  136  is then placed over the pins  132  to abut the second chain pad  200  and is retained in place by a spring clip  138  which cooperates with the annular grooves  133  proximate the ends of the pins  132 . 
     The process is repeated as a pair of chain pads  200  is attached to each of the outer links  120  of the steel chain  100 . The top surfaces  210  of this plurality of chain pads  200  forms a continuous surface for conveying articles or for driving the rollers of a conveyor. 
     OPERATION 
     FIG. 12 schematically depicts the conformance of the padded chain  90  about a sprocket  400 . In the normal configuration of the chain according to the invention, the pads enable a substantially contiguous top surface  210  as the chain  100  approaches the sprocket  400 . Where a normal outside wrap of the sprocket  400  is accomplished, the chain pads  200  will naturally rotate with the chain  100 , allowing the chain to normally wrap around the sprocket  400 . When the chain  90  is normally wrapped on the outside of the sprocket  400 , as in FIG. 12, the end  230  of each chain pad  200  tends to move away from the facing shoulder  275  of the adjacent cutout  270 , and in fact, the facing side faces  277  may actually separate. As the chain  100  leaves the sprocket, the chain pads  200  tend to rotate back toward each other and the chambers  280  on the ends  230  cooperate to smoothly re-overlap the side faces  277 , preventing each end  230  from hanging up on the end  230  on the adjacent chain pad  200 . 
     FIG. 13 shows the padded chain  90  with the second embodiment of the. chain pads,  300  reverse-wrapped around the sprocket  400 . On the reverse wrap, wherein prior art chain pads might normally press against each other and prevent the chain from conforming to the sprocket  400 , the cut outs,  370  allow the chain pads  300  to nest within each other. The padded chain  90  can thus be carried in a reverse wrap arrangement on the sprocket  400 . The curved cutouts  370  and curved top edge  390  will generally allow the chain  90  with chain pads  300  to conform to a smaller sprocket radius  400 . The chain pads according to the invention thus enable reverse wrapping the chain on a sprocket, while further having the advantage of presenting a smooth, substantially continuous surface on which to convey articles or to drive the rollers of the conveyor. 
     FIGS. 14,  15  and  16  depict different arrangements of chain driven roller conveyors, including conveyors requiring a “reverse wrapped” drive chain, the  160  environment in which reverse-wrapping chains is found to be beneficial. FIG. 14 shows an end-drive-type drive mechanism for a conveyor  10 . A drive motor  30  through a drive belt  35  rotates a drive sprocket  20  located at an end of the conveyor  10 , the drive sprocket  20  driving a padded chain  60  which, by frictional contact, drives rollers on the conveyor  10 . An end sprocket  25  secures the run of chain  60  opposite the drive sprocket  20 . In FIGS. 15 and 16, depicting conveyers  12 ,  14 , respectively, the drive sprocket  20  is located intermediate the ends of the conveyor  12 ,  14 . Chain take-up rollers  40  are arranged with the drive sprocket  20  to maintain tension on the chain  60 . Two end sprockets  25  define the end of chain travel. As can be clearly seen in FIGS. 2 and 3, the chain  60  must be capable of wrapping around the take up rollers  40  and the drive sprocket  20  in opposing directions. Advantages of the arrangements in FIGS. 2 and 3 include the ability to reverse direction of the conveyor, use less space for the drive mechanism, and enable floor level conveyor systems. 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.