Sorting system using a roller-top conveyor belt

A sorting conveyor system in which a main conveyor is intersected by one or more cross conveyors forming sorting stations at one or more gaps along a main conveying path. The cross conveyor includes a roller-top belt having rollers extending outward of a top article-supporting side and arranged to rotate about axes perpendicular to the main conveying path. The cross conveyor includes a bidirectional drive to selectively advance the roller-top belt in one of two opposite directions to discharge articles transferred onto the cross conveyor in the gap off the side of the main conveying path. The cross conveyor also serves as a low-friction roller-top bridge when the roller-top belt is stopped. The bridge allows articles to cross the gap from an upstream portion of the main conveyor to a downstream portion.

BACKGROUND

The invention relates generally to power-driven conveyors and, more particularly, to sorting systems using roller-top conveyor belts to divert articles from one side or the other of a main conveyor.

In the tire industry, finished tires leave the inspection area in a mix of various types and sizes. Usually the tires are sorted automatically, using bar codes or colored line codes to designate type or size. Transported on a sorting conveyor, the tires are identified by a bar code or color code reader, or sometimes even by a human operator that recognizes the tire type and pushes the appropriate identification button. As soon as an identified tire passes the proper exit of the sorter conveyor for that type of tire, the tire is moved sideways at a 90° angle onto an exit conveyor that conveys the tire to the proper palletizing or storage station. Classical sorting systems use a complex set up of narrow belts and pop-up driven rollers to make the 90° diversion.

Several conventional sorting systems use transverse-roller-top belts in line with a main conveyor. Simple pneumatic or electric pushers push an identified tire off the side of the transverse-roller-top belt onto an exit conveyor. A disadvantage of this system is that it is difficult to transfer tires onto exit conveyors when they are positioned opposite each other across the main conveyor.

Thus, there is a need for a less complex sorting system for tires and other articles.

SUMMARY

This need and other needs are satisfied by a conveyor system embodying features of the invention. In a first version, a conveyor system comprises a main conveyor that conveys articles on an outer conveying surface along a main conveying path. At least one cross conveyor is disposed along the conveying path. The cross conveyor, which intersects the main conveyor, includes a roller-top belt with rollers extending outward of an article-supporting surface of the belt. Axles allow the rollers to rotate about axes that are generally perpendicular to the main conveying path. A drive engages the roller-top belt to advance it along a discharge path generally perpendicular to the main conveying path.

A second version of conveyor system suitable for sorting conveyed articles comprises an upstream conveyor conveying articles along a main conveying path toward a downstream article receiver, which may be another conveyor. The article receiver is aligned with the upstream conveyor, but spaced apart from it along the main conveying path across a gap. A cross conveyor is disposed in the gap between the upstream conveyor and the downstream receiver. The cross conveyor includes a roller-top belt having rollers with axles for rotation of the rollers about axes generally perpendicular to the main conveying path. The cross conveyor also includes a drive that engages the roller-top belt to selectively stop and drive the roller-top belt bidirectionally.

In another aspect of the invention, a conveyor system comprises a downstream conveying surface and an upstream conveying surface separated along a main conveying path by a gap. A cross conveyor in the gap includes a roller-top belt. Salient portions of rollers extend above a top side of the belt to contact conveyed articles received from the upstream conveying surface. Axles allow the rollers to rotate about axes generally perpendicular to the main conveying path.

According to yet another aspect of the invention, a conveyor system for selectively discharging articles comprises a main conveyor conveying articles along a main conveying path. The main conveyor is interrupted by one or more gaps along the main conveying path. One or more cross conveyors intersect the main conveying path at the gap. Each cross conveyor includes a roller-top belt, which has rollers arranged to rotate freely. Articles received from the main conveyor on the roller-top belt are rolled across the gap by the rollers in the direction of the main conveying path. A drive engages the roller-top belt to advance it across the main conveying path to divert articles from the main conveying path.

Another version of conveyor system comprises a main conveyor conveying articles along a main conveying path. One or more gaps along the main conveying path interrupt the main conveyor. A cross conveyor in each gap intersects the main conveying path with a roller-top belt. Rollers in the belt are arranged to receive conveyed articles in the gap from the main conveyor. The roller-top belt may be advanced in at least one direction across the main conveying path. The cross conveyor also includes means for raising and lowering the roller-top belt between a first position and a second higher position. In the first position, a conveyed article is supported by both the roller-top belt and the main conveyor. In the second position, the conveyed article is lifted by the roller-top belt out of contact with the main conveyor.

And, in still another aspect of the invention, a conveyor system comprises a main conveyor conveying articles along a main conveying path. At least one gap interrupts the main conveyor along the main conveying path. A cross conveyor intersects the main conveying path at each gap. The cross conveyor includes a roller-top belt and a drive engaging the roller-top belt. Rollers in the belt are arranged to rotate freely to roll conveyed articles received from the main conveyor across the upstream end of the gap in the direction of the main conveying path. The drive engages the roller-top belt selectively to stop or advance the roller-top belt in either of two directions. While the belt is stopped, a conveyed article rides across the roller-top belt past the gap along the main conveying path. The drive may advance the roller-top belt in a first cross direction along a discharge path to divert a conveyed article from the main conveying path to a first side of the main conveying path. The drive may also advance the belt in an opposite second direction to divert a conveyed article to an opposite second side of the main conveying path.

DETAILED DESCRIPTION

A conveyor system embodying features of the invention is shown inFIG. 1. A main conveyor10defining a main conveying path12is interrupted by a gap14. An upstream conveyor16is separated by the gap from a downstream conveyor18that receives conveyed articles, such as tires20, from the upstream conveyor. Articles are conveyed along the main conveying path in the direction of arrows22on top article-conveying surfaces24of the conveyor. The main conveyor is preferably realized as a belt conveyor. In this example, the upstream conveyor includes a conveyor belt26looped around a drum or a sprocket set28mounted on a drive shaft30. A drive motor32, coupled to the shaft, rotates the sprocket set and drives the upstream belt in the direction of arrow22. The other end of the upstream belt is looped around an idler shaft and sprocket set (not shown, but similar to that for the downstream conveyor to be discussed now). The downstream conveyor is also preferably a belt conveyor with an endless belt loop27extending from an idler sprocket set29or drum and shaft at the gap to a shaft and sprocket set at the other end (not shown, but it could include a drive motor as for the upstream conveyor belt). Instead of being separately driven by its own drive motor and shaft, the upstream conveyor can be slave-driven from the downstream conveyor through jackshafts, gears, or pulleys connected between the drive elements of the upstream and downstream conveyors. Although the upstream and downstream conveyors are preferably belt conveyors, they could alternatively be realized as driven-roller conveyors, vibrating conveyors, or drag-chain conveyors, for example.

A cross conveyor34is positioned in the gap14between the upstream16and downstream18portions of the main conveyor to serve as a sorting station. The cross conveyor includes a roller-top conveyor belt36wrapped around a drive sprocket set38on a drive shaft40driven by a motor42at one end and an idler sprocket set39on a shaft at the other end. The drive motor, shafts, and sprocket sets constitute a drive for the roller-top belt. Preferably, the drive is made bidirectional, as indicated by double-headed arrow48, by using a reversing motor. Salient portions of rollers50extend outward from a top side52of the roller-top belt. The rollers are arranged to rotate about axes54that are generally perpendicular to the main conveying path12. Axles56define the axes for the rollers and retain them in the belt. A wear surface44underlies the roller-top belt along the upper carryway portion of the cross conveyor belt's path46. Conveyed articles can be diverted from the main conveyor along this discharge path in either of two opposite directions to other conveyors or receiving stations on opposite sides of the main conveying path. The drive can also stop the roller-top belt from advancing. When the roller-top belt is stopped, an article20is propelled by the upstream conveyor onto the rollers on the top article-supporting side of the roller-top belt. The rollers rotating freely as indicated by arrow58roll the article across the gap in the direction of the main conveying path onto the aligned downstream conveying portion of the main conveyor. As shown inFIG. 3, the article-conveying surfaces of the main conveyor at the gap lie in the same plane P as the top article-supporting side of the cross conveyor. In this way, the roller top belt serves as a low-friction bridge between the upstream and downstream conveying surfaces of the main conveyor.

To prevent articles from being stranded on the roller-top belt, the width W of the gap is preferably less than the dimensions D of the footprint of the articles being conveyed, as shown inFIG. 2. In the case of a tire, the critical dimension is its outer diameter. For articles having a more complex shape, the critical dimension must be determined to prevent articles from being stranded.

Although the main conveyor may be realized by a variety of conveyors, the cross conveyor is realized as a roller-top belt conveyor. And, preferably, the roller-top belt is a modular plastic conveyor belt, such as the Series 400 Transverse Roller Top belt manufactured and sold by Intralox, L.L.C. of Harahan, La., USA. Modular plastic conveyor belts are constructed of rows of molded plastic belt modules connected end to end by hinge pins through interleaved hinge eyes between consecutive rows of belt modules. In the Intralox Series 400 roller-top belt, the rollers are plastic rollers with a central bore through which a stainless steel axle is received. The ends of the axle are embedded in the interior of the module and retain the roller rotatably in place in a module cavity. Although modular plastic conveyor belts are preferred, flat rubber or fabric belts may also be used in the invention.

When the cross conveyor is activated to divert articles off one side of the main conveyor or the other, it is undesirable for the conveyed article to be in contact with the article-conveying surface of the main conveyor as the article is being diverted. This is especially true in the case of articles made of high-friction materials, such as tire rubber. As shown inFIG. 4A, an article20conveyed along the main conveyor10transfers across the gap over the bridge formed by the roller-top belt36. The sprocket sets38,39about which the roller-top belt is looped are positioned on opposites sides of the main conveyor. When the roller-top belt is stopped, there is no pull, or tension, in the belt. The weight of the article transferred onto the roller-top belt causes it to sag until it lowers to a position to sit on a wear surface44(FIG. 1). As shown inFIG. 4B, when the belt is driven in either direction to divert articles off the main conveyor, the top article-supporting side of the cross conveyor belt rises from a first lower position60′ to a second higher position60. As the belt36is driven in either direction48, belt pull, or tension, in the belt increases. The increased tension takes up the sag in the top carryway portion of the belt and causes it to follow more closely a tangent line between the outer peripheries of the two sprockets38,39, which are elevated with respect to the plane P of the outer article-conveying surfaces of the main conveyor. Consequently, the cross conveyor belt is in a lower position to bridge the gap when the cross conveyor belt is not running and in a higher position lifting the conveyed article off the main conveyor when the cross conveyor belt is advancing to discharge articles off the side of the main conveyor. Thus, the elevated sprockets and the drive system constitute means for raising and lowering the roller-top belt.

FIGS. 5A and 5Bshow another version of the conveyor system with a differently configured main conveyor. In this version, the main conveyor is formed of a single conveyor belt62following an upper carryway path64and a lower returnway path65. Conventional sprockets, rollers, and shoes (66, generally) are used to guide the main conveyor belt along its path. The top carryway portion of the main conveyor upstream of the gap14serves as an upstream conveyor, and the downstream top carryway serves as a downstream conveyor. In the gap, the main conveyor belt resides below the cross conveyor34. In this way, a single belt with a single drive can be used in the main conveyor. The cross conveyor can be configured as inFIGS. 4A and 4Bwith the sprockets elevated to allow the cross conveyor belt to assume a lower position as inFIG. 5Ato allow the article to transfer across the gap and stay on the main conveyor or a raised position as inFIG. 5Bto divert articles off the main conveyor to either side of the belt without frictional contact with the main conveyor. A lift mechanism, indicated by arrow67, and realized as a pneumatic or hydraulic piston, for example, could alternatively be used to actively raise and lower the cross conveyor relative to the main conveyor in coordination with the cross conveyor belt drive. AsFIGS. 5A and 5Bfurther show, a sensor68is positioned along the main conveying path to sense one or more characteristics of a conveyed article. For example, the sensor could be a proximity switch that detects the presence of an article approaching the gap by a signal sent over a signal line70to a controller72, such as a programmable logic control or other intelligent controller. The controller controls the activation of the cross conveyor drive to stop the cross conveyor belt or drive it in one of two opposite directions. The sensor or other sensors could also or alternatively be optical sensors, bar code readers, RFID sensors, or other sensing devices capable of sensing specific characteristics of the conveyed article to control the sorting of articles transferred onto the cross conveyor.

Although the invention has been described in detail with respect to a few preferred versions, other versions are possible. For example, the main conveyor may include more than one gap to allow for many cross conveyor sorting stations. As another example, if stranding is not a problem, the gap width need not be less than a critical dimension of the footprint of a conveyed article. And the cross conveyor need not be perpendicular to the main conveyor, but could define a discharge path at some oblique angle to the main conveying path. As yet another example, a stationary article receiving station can replace a downstream conveyor in receiving articles conveyed over the cross conveyor. Furthermore, to avoid the problem of friction by rubbing contact between a conveyed article and the main conveyor during article diversion, the main conveyor can include a roller-top belt with transverse rollers along which conveyed articles can roll as they are being discharged toward the side. So, as these few examples suggest, the scope of the claims is not meant to be limited to exemplary versions described in detail.