Conveyors: power-driven – Conveyor having impinging fluid to feed – shift or discharge... – Having cleaning means
Reexamination Certificate
1999-12-22
2001-09-04
Noland, Kenneth W. (Department: 3651)
Conveyors: power-driven
Conveyor having impinging fluid to feed, shift or discharge...
Having cleaning means
C015S256500
Reexamination Certificate
active
06283274
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to an apparatus for the cleaning of material handling conveyor belts. The invention relates specifically to an apparatus for increasing, over time, a biasing of force exerted by a scraper blade against a conveyor belt.
BACKGROUND OF THE INVENTION
Conveyors are used extensively to transport materials, such as sand, gravel and coal, from one location to another. Continuous conveyor belts are often used to efficiently, effectively, and continuously transport material. It is a problem that with continuous conveyor belts that material often adheres to the conveyor belt, due to moisture and other conditions, after the material has passed the intended delivery point. Material that remains on the belt can interfere with the proper functioning of the conveyor system by way of increased wear and tear on the conveyor belt and damage to the rollers supporting the belt on the return section of the continuous loop.
Several devices disclose the use of scraper blades to remove materials that have adhered to the conveyor belt. These devices are effective for a period of time, but only with frequent adjustments or tensioning throughout the entire wear life of the scraper blades. Scraper blades tend to wear over time; typically, in one to one and a half years, the scraper blades need to be replaced. As the scraper blades wear down, several phenomena occur. Firstly, the surface area of the blade that is in contact with the conveyor belt increases as the blade wears. Secondly, the biasing force of the support arm of the blade against the belt diminishes over time, thereby causing insufficient biasing of the blade against the belt. Thirdly, the arm that biases the blades against the belt must be adjusted so as to enable the blades to exert sufficient force against the belt as the blade wears. Otherwise, the blades do not remain biased against the conveyor belt with sufficient force to permit the effective scraping of material from the belt. Typically, the support arm is adjusted manually to bias the blade against the belt. Manual adjustment of the support arm requires shutting down the conveyor line. As the blades wear, more frequent adjustment of the support arm is necessary. As one can readily appreciate, frequent intermittent manual adjustment of the arm results in downtime and efficiencies. Moreover, even frequent adjustment of the support arm does not adequately compensate for the continuous wearing of the blades.
Thus, a tensioner is needed to overcome the continuous loss of biasing force such that the biasing force of the arm and blade against the belt remains sufficient, as the blade(s) wear, so as to permit effective cleaning of the belt. Also needed is a tensioner with a useful life at least as long as the useful life of the scraper blade(s). Further, a self-adjusting tensioner is needed which compensates for the wearing of the scraper blade and corresponding loss of biasing force in the arm and blade, with virtually no manual adjustment of the support arm, such that the use of the scraper and tensioner remains substantially uninterrupted.
SUMMARY OF THE INVENTION
The present invention is directed to a tensioner that automatically increases the effective torque on the support arm over time. The tensioner is comprised of a torsion cam, torsion cable, tension rod, and spring. The tensioner is coupled to a scraper blade support arm. As the scraper blade wears down, the spring expands away from the mounting plate. As it expands, the spring exerts a force against a spring retainer to which is secured one end of the tension rod, thereby causing the tension rod to move away from the mounting plate. The other end of the tension rod is secured to a first pin member to which is secured a cable at one end. The opposite end of the cable is also secured to a second pin member, which, in turn, is secured to a torsion cam. Movement of the spring and torsion rod away from the mounting plate causes the cable to be pulled in the direction of the movement of the torsion rod. As the cable is pulled, at the first pin member, by virtue of the cable's engaging the torsion cam, the torsion cam rotates, about its axis of rotation, in a clockwise direction. As the torsion cam rotates, the length of the torque arm (i.e., the distance between a point on the axis of rotation co-terminus with the end of the torsion cam opposite the mounting plate and the intersection point of the cable as it leaves the torsion cam) increases. As the length of the torque arm increases, the effective torque on the support arm increases, thereby causing the biasing force of the support arm and blades against the belt to increase. In a preferred embodiment, this invention is particularly suited for use with a scraper assembly such as the one disclosed in U.S. patent application Ser. No. 08/818,839, entitled, “Method and Apparatus for Cleaning a Conveyor Belt”. However, as one of ordinary skill in the art will readily appreciate, the tensioner of the instant invention can be adapted for use with virtually any existing scraper blade assembly.
It is an object of the subject invention to provide a device that automatically increases the effective torque on the support arm of the scraper blade, thereby increasing the biasing force of the support arm (and scraper blade) against the conveyor belt.
It is also an object of the subject invention to provide a system that requires no manual adjustment or tensioning throughout the entire wear life of the scraper blades and spring.
It is a further object of the subject invention to provide a tensioner that is universally mountable to any existing scraper assembly and can be retrofitted to a wide range of other tensioners.
The apparatus of the present invention is further illustrated by the following detailed description and accompanying drawings.
REFERENCES:
patent: 3631968 (1972-01-01), Ward
patent: 4352425 (1982-10-01), Childress et al.
patent: 4359150 (1982-11-01), Bowman et al.
patent: 4533035 (1985-08-01), Reiter
patent: 4633999 (1987-01-01), Perneczky
patent: 4917231 (1990-04-01), Swinderman
patent: 4936439 (1990-06-01), Alexander, Jr. et al.
patent: 5114000 (1992-05-01), Rappen
Dolan Troy D.
Gibson Joseph
Noland Kenneth W.
The Bilicki Law Firm P.C.
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