Conveyors: power-driven – Conveyor having impinging fluid to feed – shift or discharge... – Having cleaning means
Reexamination Certificate
2000-06-21
2001-08-28
Ellis, Christopher P. (Department: 3651)
Conveyors: power-driven
Conveyor having impinging fluid to feed, shift or discharge...
Having cleaning means
Reexamination Certificate
active
06279727
ABSTRACT:
FIELD OF THE INVENTION
This invention relates a cleaner apparatus for a conveyor belt to scrape material from the belt.
BACKGROUND OF THE INVENTION
The present invention is directed to providing a belt scraper which is relatively low in cost and simple in construction in comparison to many conventional belt scraper apparatuses. For example, one more complex belt scraper employs a closed parallelogram linkage of four links having an internal, inflatable diaphragm to bias the links and a belt scraper blade against the underside of a conveyor belt. Such a system is relatively complex in that it requires a source of compressed gas to inflate the diaphragm and protective flaps to deflect the scrap debris from clogging the parallelogram linkages. The parallelogram linkages comprise four pivotally connected, steel link members two of which are generally horizontal, and the other two of which are generally inclined to the vertical. As the belt wears the tip away, the diaphragm pushes the linkages to raise the blade tip to continue scraping pressure against the conveyor belt. It will be appreciated that wet material, dirt and clays or sands or gravel or other caustic materials being conveyed by the conveyor belt can deposit in or about the linkages and interfere with the operation of the linkages. Also, the initial cost of a particular linkage and the gas bag add to the cost and the maintenance problems associated with this particular system.
The present invention is also directed to providing a belt scraper that is usable with belts spliced with mechanical belt splices made of metal belt fasteners. These metal belt fasteners strike the belt scraper, unless a mechanism is provided to lower the belt scraper upon approach of the belt fasteners. The belt scraper's striking of the metal fasteners can damage the splice, gouge the scraper blade and vibrate the scraper blade and generate noise. There is a need for a more fastener-friendly belt scraper that allows downward travel of the scraper blades and a cushioning of the impacts between the belt scrapers and the metal belt fasteners.
Another form of belt scraper device, such as disclosed in U.S. Pat. No. 3,841,470, uses an elastomeric block of solid rubber or synthetic resin to mount the blade. The blade holder includes a vertical plate fixed to a vertical face of the block; and there is a mild elastic deformation of the resilient member to provide the biasing force. This system does not provide much cushioning because of its rigidity. Further, this system does not maintain the blade pressed against the belt with sufficient force with wear of the scraper blade so that frequent force adjustments are necessary. It is most desirable that blade pressure be maintained without frequent adjustments or other kinds of maintenance.
It will be appreciated that belt scrapers for conveyors are often exposed to ambient weather conditions which can be either very hot during summertime or very cold in wintertime. Preferably, the belt scraper functions adequately in very cold temperatures where ice and snow accumulations may be formed on the conveyor belts and scrapers in addition to the dirt, clay, sand, caustic materials, etc. that are always present. When exposed to high temperatures, the belt scraper materials and biasing force elements must not deteriorate and lose their effectiveness.
It has been found that the blade mounts and the blades of the scraper may experience a considerable amount of vibration over a particular time period and with a large amplitude of vibration caused by the blades impacting mechanical belt fasteners. It is desirable to reduce the duration and amplitude of the vibrations in an inexpensive manner. It is further desired to provide a scraper blade and mount that dampens the vibration of the blades, while in use, and thereby increases their life against failure due to fatigue of the materials used.
Also, there is a need for a scraper blade system for scraping the conveyor belt that allows the belt to be reversed in the opposite direction and still provide a scraping of the belt bottom surface. The scraper blade system should provide the requisite force or pressure between the scraping blade and the belt, even though the wear occurs, by shifting the blade upwardly to take up the wear and to maintain the scraping pressure to remove the debris from the belt.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a new and improved belt scraper apparatus having scraper blades each mounted on an elastomeric blade mount body having integral portions formed thereon for deflection to provide a cushioning of the blade and a spring biasing force to urge the blade tips against the belt surface being cleaned. Herein, this is achieved by an elastomeric blade mount body which is a block-shaped body having a flexible, central, elongated portion preferably including a pair of generally parallel legs or arms, which may be flexed as the scraper is forced against the belt with the legs trying to return to their original non-flexed positions as the scraper blade wears.
The preferred elastomeric body can be made relatively inexpensively by being formed as a one-piece block of elastomeric material. The particular opening therein is preferably I-shaped defining a pair of upper and lower horizontal legs attached to the pair of vertical legs at points that acts as flexure points. The preferred body acts as a parallelogram when deflected and acts as a cushion mounting for the scraper blade. The vertical legs may be bent and deformed substantially, e.g., in a range of 15°-40° with respect to the vertical; while the horizontal legs maintain the blade tip substantially perpendicular to the conveyor belt surface. The particular elastomeric blade mount body is relatively corrosion-resistant and a low maintenance item which needs neither to be greased nor, in the usual case, to be protected by flaps from dirt or other debris on the conveyor.
In the preferred embodiment of the invention, a filler material is inserted into and fills the opening while still allowing the legs or arms to deflect. The preferred filler material is a foamed material which fills the opening and seals the opening against the intrusion of dirt or other foreign materials. The preferred foamed material is a closed cell, rubber foam which dampens vibrations in the elastomeric body and thereby, decreases the fatiguing of the elastomeric body. Because the elastomeric body is filled and has little or no exposed metal, there is no corrosion and there is little dirt or ice build-up inside the cushion that could affect the deflection of the legs of the elastomeric body.
In accordance with the invention, the preferred elastomeric blade mount is made of and selected from various elastomeric materials to have the properties of a good fatigue life and a low compression set. The typical elastomerics have static compression sets in the range of about 20% to 40%; while the preferred elastomeric is a polyurethane having a lower static compression set of about 13%. This lower compression set material, while still providing good flexibility and cushion characteristics, serves to maintain a more constant pressure force between the blade surface and the conveyor belt, e.g., in the range of 10 to 20 lbs./inch
2
. The low compression set elastomeric material increases the time between adjustments of the belt cleaner apparatus to keep the pressure contact within the desired range for good cleaning of the conveyor belt.
In accordance with another aspect of the invention, the blade mounts are mounted vertically on a lower, adjustable support which can be moved up, relative to the belt, to force the spring legs or arms of the mount against the belt with a high pressure. When the belt is moving at its normal speed, the friction force of the belt on the scraper blade will bend the vertical legs through an angle, e.g., 15°-20° to the vertical. These bent legs bias the blade with a pressure force against the belt of a predetermined amount usually in the range of 10-20 lbs./inch
2
Gleason Dennis L.
Waalkes Jon Robert
Dillon, Sr. Joe
Ellis Christopher P.
Fitch Even Tabin & Flannery
Flexible Steel Lacing Company
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