Conveyors: power-driven – Conveyor having impinging fluid to feed – shift or discharge... – Having cleaning means
Reexamination Certificate
1998-12-30
2001-02-06
Ellis, Christopher P. (Department: 3651)
Conveyors: power-driven
Conveyor having impinging fluid to feed, shift or discharge...
Having cleaning means
Reexamination Certificate
active
06182816
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to conveyor systems and is particularly applicable to a novel scraper adapted to bear against a head pulley to scrape the material from the belt as it travels around the head pulley. The invention has particular application to conveyors for conveying wet materials which tend to adhere to the conveyor belt.
BACKGROUND OF THE INVENTION
Conventional belt conveyors typically have a plurality of scraper assemblies disposed to remove deposits adhering to the surface of the conveyor belt. For example, it is common to provide a scraper assembly at or near the head pulley to clean the belt as the belt begins its return travel. Additionally, trailing arm scrapers are commonly located along the length of the belt in between the head and tail pulleys to provide additional cleaning.
A common type of scraper blade assembly comprises a plurality of mounted scraper blades extending across the transverse axis of the conveyor belt. The blades are mounted on support arms which are fixed to and extend from a transverse rotatable support shaft. Rotation of the transverse support shaft moves the scraper blades into and out of contact with the conveyor belt. Applying a torque to the support shaft increases the contacting force of the scraper blades against the belt.
During installation and use of the scraper blade assemblies, the belt scraper blades wear down.
A high durometer polyurethane scraping blade will not wear as quickly as a lower durometer blade, but the higher durometer blade will impart greater stress to the conveyor belt and it is more likely to damage poorly-made splices in the conveyor belt, and is less able to adapt itself to conform to the contour of the belt as it wears.
Where it is desirable to provide more flex in the scraper blade, it is desirable to use a 82-85 durometer blade which has a thickness of 1¼″ or less. When conventional blades of the prior art are used, the thickness of the blade gradually increases from the tip all the way back to the mounting base, and the greatest flexibility is at the tip where the blade sharply tapers to a relatively sharp edge along its length. After the blade wears through the sharply-tapered tip, the conventional blade loses its high flexibility.
With wet and sticky materials or materials which accumulate due to freezing or evaporation, the scraper blade tends to accumulate materials scraped from the belt on the under surface of the blade which confronts the belt. If the material accumulated on the blade builds up to a substantial degree, it cakes on the under surface and may engage the belt downstream from the scraping edge of the blade and cause the scraping edge to disengage the surface of the belt, or may serve as a dam or block against the bias of the blade holder forcing the scraping edge of the blade against the belt to take advantage of the flexible nature of the blade.
SUMMARY OF THE INVENTION
With the foregoing in the mind, the present invention provides a novel blade design which overcomes the deficiencies of the prior art blades.
More specifically, the present invention provides a blade configuration which enables the under surface of the blade to confront the belt at an angle which is sufficiently steep to allow some accumulation of material on the under surface of the blade without building up a cake which is large enough to displace the blade away from the belt.
In a preferred embodiment, the blade has a base adapted to be replaceably mounted on a support shaft which is operable to rotate the blade against the conveyor belt with a pressure bias, and the under surface of the blade extending from the base to the scraping edge is recessed.
Specifically, the preferred blade has a metallic base portion adapted to be releasably engaged on the support shaft with a resilient blade molded integrally with the metallic support base. The blade is formed of an elastomeric material such as plastic, capable of resiliently flexing to conform to the contour of the conveyor belt as it traverses past the blade on the head pulley. The resilience of the elastomeric material assists the dislodgment of material accumulated on the blade during operation. The elastomeric blade is offset adjacent the metal base so as to provide a straight under surface confronting the head pulley throughout the wear portion of the blade.
REFERENCES:
patent: D. 347918 (1994-06-01), Gibbs
patent: 4825996 (1989-05-01), Davidts
patent: 4962845 (1990-10-01), Gibbs
patent: 5011002 (1991-04-01), Gibbs
patent: 5016746 (1991-05-01), Gibbs
patent: 5114000 (1992-05-01), Rappen
patent: 5197587 (1993-03-01), Malmberg
patent: 5222589 (1993-06-01), Gordon
patent: 5573102 (1996-11-01), Puchalla
patent: 5865294 (1999-02-01), Betz
patent: 2221440 (1990-02-01), None
Gibbs A. Todd
Mott George T.
ASGCO Manufacturing, Inc.
Dann Dorfman Herrell and Skillman
Eland Stephen H.
Ellis Christopher P.
Tran Khoi H.
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