Knuckle linked type of link conveyor belt systems are well known in the art as exemplified by U.S. Pat. Nos.: 3,768,631, Oct. 30, 1973 to E. J. R. Wahren for Conveyor Belt Chain; 4,597,492, Jul. 1, 1986 to Lachonius, et al. for Conveyor Chain; and 5,402,880, Apr. 4, 1995 to J. F. Murphy for Article Carrying Chain Having Free Tab.
A primary deficiency of prior art knuckle linked conveyor belt systems has not been satisfactory because of the lack of diversity. Each system thus has a tendency to be custom engineered and constructed for a particular installation, product line or conveyor path configuration.
Thus an object of the present invention is to provide versatile links and conveyor systems of the knuckle linked type that are well adapted to universal use over a large range of applications, product lines and path configurations.
This type of prior art has been particulary unsatisfactory because it presents difficulties in required custom engineering, molding and assembling such plastic conveyor belt systems in order to meet the demands of new installations and products.
The versatility has not been present for example to provide conveyor belt systems that require long meandering paths that both curve laterally along the way and pass up and down declines. These installations, for example, must be adaptable to various types of drive configurations at different positions along the belt length in order to provide proper drive power to carry loads, to navigate curves, particularly in curves where the tension and loading on the belt is greatest.
Features of strength, life span, maintenance and repair access are most important when using molded plastic links. In addition the ability to mold link bodies that withstand the rigors of industrial use for various types of products is a continuing challenge in the art.
Some of the variations encountered that challenge the operation of such belt systems is the ability to produce at will in conveyor belt links the slickness needed to reduce driving power in movements about curves, sprockets and in contact with frictional surfaces of wear plates at belt edges and bottom parts of the belt which may be positioned at specified locations along the belt pathway. The uneven loading on the belt as it passes work stations or moves up inclines may demand installations of auxiliary drive sprockets.
Improvements are needed to the driving of belts under diverse operating conditions. The conventional sprocket drive systems that engage the bottom of the belt usually are located at belt loops requiring complex structure for transfer of products from one belt to another over long transport paths.
Furthermore, both the repair or maintenance of such belts in service and the initial belt installation in the prior art systems are difficult and time consuming. Access to the belt at a loop sprocket location of an industrial installation, for example, may be limited, and repairs may take the belts off line for long periods of time.
In the initial installations, the formation of a knuckle linked type belt from separate links provides a significant challenge. Thus the complex task of aligning and interconnecting belt links end-to-end require the knuckle to be held in precise alignment with spindle rods passed through nose end knuckle joints and the bifurcated trailing legs of a leading link. It is desirable to decrease the complexity of this task, including avoiding the nuisance of knuckles dropping out of position and falling to the floor.
A further problem is that these knuckle drive type conveyor chains have been limited in the types of sprocket drive configuration, without flexibility for example to interface with different sprocket drive systems which may be encountered.
Furthermore these systems have the limitation of integrally disposed conveying surfaces formed by the belt links, so that different basic links have to be designed and stocked for providing the different kinds of conveyor surfaces suitable for different products being conveyed, and different configurations of belts such as those which may travel on inclined paths, for example.
Other types of link conveyor belts have been adaptable to replaceable drive pads or modular overlays such as shown in U.S. Pat. Nos. 5,004,097, Apr. 2, 1991 to G. C. Roinestad, et al. for Replaceable Snap-on Modular Overlay for Rod and Link Turn-curve Conveyor Belts; and (FIG. 8) 5,582,287, Dec. 10, 1996 for Drive Chain for Accumulation Conveyor. Such replaceable drive surfaces however, present various problems such as forming a substantially continuous surface between links, without lateral spaces or cracks that can cause problems in conveying products that might pass over or rest on such spaces and cracks.
In knuckle drive type link belts, it has not heretofore been feasible to integrate such removable drive surfaces and overlays compatibly with the configuration restrictions of belts that have curving and inclined pathways for carrying various product lines.
It is therefore an objective of this invention to overcome such problems and deficiencies of prior art and to provide improved versatile knuckle joint type chain links and corresponding belt conveyor systems.