Conveyors: power-driven – Conveyor section – Endless conveyor
Reexamination Certificate
1999-11-05
2001-11-20
Bidwell, James R. (Department: 3651)
Conveyors: power-driven
Conveyor section
Endless conveyor
C198S779000
Reexamination Certificate
active
06318544
ABSTRACT:
BACKGROUND
1. Field of the Invention
The invention relates to article conveyors generally and, more particularly, to conveyors having an article-conveying surface with article-engagement characteristics that can be changed while the conveyor is running.
2. Description of the Related Art
Conveyor belts are used widely to transport articles through plants. During its odyssey through a plant, an article encounters a variety of challenges. For example, the article may need to descend from one level to a lower level or to climb from the lower level to a higher level. To give the article some traction on an incline or to prevent it from sliding out of control down a decline, conveyor belts with rubber or other high friction materials on the conveying surface are used. At other places in the plant, a number of articles must be accumulated because, for example, a downstream process is proceeding more slowly than an upstream process. To prevent the accumulating articles from crushing each other as the conveyor belt continues to move, a belt having rollers providing a low-friction conveying surface is used. The rollers allow the belt to slide past the undersides of the accumulated articles with little backline pressure. Sometimes it is necessary to space the articles from each other. Singulators with a controlled gate are often used to separate conveyed articles from each other. Finally, an article's journey through the plant ends. Often the article is pushed off the side of the belt onto a platform for shipment. A belt with rollers capable of rotating in a direction to aid a side-off transfer is useful in this application.
The response to one challenge confronting the article as it travels through the plant is often incompatible with the other challenges. Consequently, the common solution is to use a series of conveyors each having a conveying surface characteristic suited to overcoming the particular challenge. But this solution requires a number of different-style belts, more belt drive systems, and more plant space to handle the additional feet of belt, drive components, and transfer mechanisms required. Thus, there is a need for a conveyor system that can handle combinations of these conflicting transport requirements of high-friction conveyance, low-friction conveyance, side-off transfer, low backline pressure, and product separation.
SUMMARY
This need and others are solved by a conveyor system having features of the invention. Such a conveyor includes a conveyor frame supporting a driven conveyor belt. The belt includes an outer conveying surface and an opposite inner surface. An opening is formed in the outer surface. A movable assembly is disposed in the opening. The movable assembly includes an article-supporting element that is capable of being positioned above the outer conveying surface to support conveyed articles and an adjustable element at or below the inner surface of the belt. An adjustment control element supported in the conveyor frame coacts with the adjustment element as the belt is running. The coaction causes the adjustment element to move the movable assembly and the article-supporting element into a different relationship with the supported articles to provide them with a different conveying characteristic. In this way, a single belt can be used to provide conveyed articles with different conveyor characteristics along the conveying path to meet various requirements.
In one version, the movable assembly is a retractable assembly that includes a retractable element that is movable from a first retracted position within the opening and below the conveying surface to a second salient position above the conveying surface. The conveyor frame supports a bearing member close to the inner surface of the belt along a portion of the conveying path. The bearing member bears against the retractable assembly to urge the retractable element from the first retracted position to the second salient position to support conveyed articles from below. Thus, by positioning bearing members at strategic locations along the conveying path, one can “program” the belt to present a different characteristic to supported articles where needed.
Different versions of conveyors having features of the invention have different retractable assemblies and elements. In one version, the retractable assembly is a cradle-mounted roller. By bearing against a camming surface of the cradle, the bearing member forces the roller through the opening above the upper surface of the belt to provide rolling contact to conveyed articles. Depending on the orientation of the roller's axis of rotation, this version is useful for low backline pressure or side-off transfer.
According to yet another version, the retractable assembly includes an adjustable rotatable wheel below the inner surface of the belt. An adjustment control rack of predetermined length in the direction of belt travel is supported in the conveyor frame near the inner surface of the belt. The forward motion of the belt causes the wheel and the retractable element to rotate about an axis normal to the conveying surface as the wheel rides along the rack. The length of the rack determines the extent of the rotation of the retractable element. In one embodiment, the wheel includes a set of circumferentially arranged gear teeth. The rack includes a set of teeth that mesh with the wheel's teeth to rotate the retractable element to a known orientation. By selecting the length of the rack, the amount of rotation of the retractable element can be set for the application. In the case of a cylindrical roller, its axis of rotation relative to the direction of belt travel can be adjusted. In this way the conveyor can be set with the axis of rotation of the roller transverse to the direction of belt travel for low backline pressure or oblique for side-off transfer.
In yet another version of the invention, the retractable member is a ball rotatably retained in the retractable assembly. According to one version, the ball can be urged to the second salient position by an arm pivotable at one end and having two camming surfaces at the other end. The bearing member bears against one of the camming surfaces to pivot the arm causing the other camming surface to push the retractable element into the second salient position.
The versions using rollers and rotatable balls, both providing low friction support for conveyed products, are useful with high-friction conveying surfaces. When the retractable elements pop up above the high-friction conveying surface, the belt surface characteristic experienced by the conveyed articles is transformed from high friction to low friction in a zone determined by the placement of the bearing members. In this way, a single belt can be programmed into zones having vastly different characteristics along the conveying path.
In another version of the invention providing article separation, the retractable assembly includes a pair of braces supporting a rotatable roller. The bearing member bears against the roller to push the assembly upward into the second salient position and to actively rotate the roller as the belt moves. Because the roller rotates relative to the belt conveying surface, articles coming into contact with the tops of the rotating rollers are accelerated. The acceleration causes consecutive articles to separate from each other in the direction of belt travel.
In yet another version, the retractable assembly includes a shoe having non-rolling upper shoe structure protruding above the conveying surface of the belt when the bearing member forces the shoe into the second salient position. The upper shoe structure is preferably made of a high-friction material. Thus, when the shoe is forced into the salient position, the belt's conveying characteristic is converted into high friction for incline and decline applications, for instance.
In any of the embodiments, biasing means, such as a spring, residing in the opening can be used to bias the retractable element toward the first retracted position. This keeps
Greve Christopher G.
Lapeyre Robert S.
O'Connor Gerald M.
Bidwell James R.
Cronvich James T.
The Laitram Corporation
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