Abstract:
A low-profile tensioner for a conveyor belt scraper that utilizes an elastomeric collar having a force storing means in the form of a series of spokes, wherein the elastomeric collar is tensioned and then connected to the rotatable shaft of the conveyor belt scraper assembly to bias the scraper against the surface of the conveyor belt while providing adequate space around the tensioner to allow for the easy adjustment or maintenance of the tensioner.

Description:
This invention relates in general to a tensioner for a conveyor belt scraper assembly and, more particularly, to a low-profile tensioner that utilizes an elastomeric collar having a series of spokes, wherein the elastomeric collar is tensioned and then connected to the rotatable shaft of the conveyor belt scraper assembly to bias the scraper against the surface of the conveyor belt while providing adequate space around the tensioner to allow for the easy adjustment or maintenance of the tensioner. 
     BACKGROUND OF THE INVENTION 
     Transportation of materials or products to remote locations or along a production line, such as in the mining or manufacturing industries, is often accomplished through the use of conveyor belts. In use, employees or machines place the materials or products on the conveyor belt at one location and the conveyor belt carries those goods to another location for further processing or unloading. During the process, particles frequently accumulate on the conveyor belt surface. Without the removal of the particles, the conveyor belt may become inoperative. Thus, a conveyor belt scraper is often used to remove the particles from the conveyor belt surface. As the scrapers, which are often polyurethane, will wear down from continued use, it is important to ensure that the belt scraper remains in contact with the conveyor belt surface to remove the particles. 
     Heretofore, it has been known to use tensioning devices utilizing torsion tubes or mechanical springs to bias the conveyor belt scraper into engagement with the conveyor belt surface. For example, U.S. Pat. No. 4,533,036 teaches the use of an elastomeric torsion tube that may be twisted and then connected to a collar attached to the rotatable shaft. The torsion tube of this tensioner needs to be of a certain length to allow for the creation of a sufficient torsional force to continually bias the scraper blade against the conveyor belt surface. Thus, it was sometimes difficult to adjust or maintain the tensioner because of the limited clearance or space between the tensioner and a wall or structure located adjacent to the conveyor belt structure. 
     Problems also occurred with the use of mechanical springs as tensioners. In particular, as the environment in which conveyor belt scrapers are used is often wet, dirty and corrosive, problems arose due to the buildup of particles or dirt between the coils of the springs or because of the corrosion of the spring. Additionally, the limited travel of the springs commonly required subsequent adjustments to the tensioners to ensure that the belt scrapers engaged their respective conveyor belt surface. 
     Therefore, there is a need for a low-profile tensioner that avoids the above problems and allows for the adjustment or maintenance of the tensioner while insuring that the belt scraper remains in contact with the conveyor belt surface to effectively scrape the conveyor belt. 
     SUMMARY OF THE INVENTION 
     The tensioner of the present invention overcomes the above problems in providing a low-profile tensioner that allows for adequate space to adjust and maintain the tensioner, while maintaining the scraper blade in contact with the conveyor belt surface. The tensioner is used with a conveyor belt scraper assembly that includes a conveyor belt scraper attached to a rotatable shaft that extends transversely and in spaced relation to the surface of the conveyor belt. At one end, the rotatable shaft extends through a fixed member and the tensioner. The tensioner, which is attached to the fixed member through a rigid collar, includes an elastomeric collar that has a series of spokes connecting an inner ring to an outer ring. A sleeve, connected at its base to the inner ring, extends through the elastomeric collar and is sized to allow the rotatable shaft to pass through. 
     Once the tensioner is assembled over the rotatable shaft and connected to a fixed member, the rotatable shaft is rotated until the scraper blade engages the conveyor belt surface. A tensioner wrench or other tool then may be used to load the elastomeric collar so that a torsional force is applied to the scraper blade shaft. The collar includes an outer ring connected to the fixed member, an inner ring concentric to the outer ring and connected to a sleeve receiving the shaft, and spokes interconnecting the rings. With the scraper blade biased against the conveyor belt surface, a locking pin or other device is used to connect the sleeve and inner ring of the elastomeric collar to the rotatable shaft, thereby acting to bias the scraper blade against the conveyor belt surface. 
     It is therefore an object of the present invention to provide a new and improved tensioner for a conveyor belt scraper that is compact and of a low-profile to minimize the space required in a conveyor installation and facilitate the adjustment and maintenance of the tensioner. 
     A further object of the present invention is to provide a new and improved conveyor belt scraper tensioner that utilizes a collar made of an elastomeric material having excellent wear characteristics, thereby increasing the life of the tensioner. 
     It is still a further object of the present invention to provide a new and improved conveyor belt scraper tensioner that utilizes an elastomeric collar having spokes connecting an inner ring to an outer ring to provide a low-profile tensioner that maintains the scraper blade in biased contact with the conveyor belt surface. 
     A still further object of the present invention is to provide a new and improved conveyor belt scraper tensioner that utilizes an elastomeric material having excellent memory characteristics to ensure that the scraper blade remains engaged with the conveyor belt surface as the scraper blade wears down. 
    
    
     Other objects, features and advantages of the invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings, wherein like reference numerals refer to like parts. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a vertical elevational view of the low-profile tensioner of the present invention attached to a conveyor belt scraper showing the clearance provided between the tensioner and an additional structure or fixed member to the right of the tensioner; 
     FIG. 2 is a perspective view of the conveyor belt scraper assembly of FIG. 1 showing the scraper blade rotated into engaged position with the conveyor belt; 
     FIG. 3 is an exploded perspective view of the tensioner device and rotatable scraper blade shaft of FIG. 1 showing the locking pin insertable into one of the holes on the sleeve and through a locking hole on the rotatable shaft to connect the tensioner to the rotatable shaft and scraper blade; 
     FIG. 4 is an axial sectional view of the low-profile tensioner of the invention; and 
     FIG. 5 is a perspective view of a tensioner wrench used to apply the torsion in the low-profile tensioner of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and particularly to FIGS. 1 to  3 , the improved tensioner of the present invention for a conveyor belt scraper, generally designated by the numeral  10 , is illustrated in use with a conveyor belt scraper assembly  20 . The conveyor includes a head roller  14  that is carried on a shaft  16  suitably supported in bearings mounted on fixed frame members  18  and  19 . A suitable drive means (not shown) is provided to drive a conveyor belt  12  that is trained over the head roller  14 . The scraper assembly  20  functions to remove unwanted particles and debris from the carrying surface of the conveyor belt  12 . 
     The scraper assembly  20  includes at least one scraper blade  22  mounted on a shaft sleeve or housing  24 . While a one-piece scraper blade, such as the urethane Saber Blade made by Arch Environmental Equipment, Inc. of Paducah, Ky., is shown in FIGS. 1 and 2, it is appreciated that this invention may be used with other one-piece scraper blades, multiple-piece scraper blades, or blades that are integral with a shaft sleeve. It is also appreciated that the scraper blade or blades may extend across all or part of the conveyor belt. 
     A rotatable shaft  26  extends through the shaft sleeve  24  in spaced relation to the surface  28  of the conveyor belt  12 . A plurality of bolts  30 , or other suitable fastening means, may be used to connect and lock the shaft sleeve  24  to the rotatable shaft  26 . Although the rotatable shaft is shown in two sections as particularly seen in FIG. 1, which may facilitate assembly at the conveyor, it will be appreciated that a single shaft may be used. The rotatable shaft  26  is rotatably supported on the fixed frame member  19  at one end, and on the fixed frame member  18  and through the tensioner  10  at the other end. As more particularly described hereafter, the rotatable shaft  26  is locked to the tensioner  10  through the use of a locking pin  42 . 
     As best shown in the exploded view of the tensioner in FIG. 3, the tensioner  10  includes a rigid collar  44  for attachment to a frame, an elastomeric collar  46  connected to the rigid collar and the frame and having a steel sleeve  48  bonded thereto, and the locking pin  42  for connecting the sleeve of the tensioner  10  and the elastomeric collar to the rotatable shaft  26 . The rigid collar  44  is preferably made of steel, but may be made of any suitable rigid material, and is attached to the fixed frame member  18  by a plurality of bolts or other suitable fastening means. When attached to the fixed member  18 , a central hole  50  in the rigid collar  44  aligns with the opening in the fixed member  18  through which the rotatable shaft  26  extends. 
     The elastomeric collar  46  includes an outer ring  60 , an inner ring  62  concentric to the outer ring, and suitable force storing means interconnecting said rings. The force storing means is preferably in the form of a plurality of radially extending spokes  58  disposed intermediate to the side edges of the rings. While the force storing means is shown as spokes, it is appreciated it may be a solid annular member. The outer ring  60  is connected to the rigid collar  44  by a plurality of bolts  52  extending through holes  53  of the outer ring, thereby securing the elastomeric collar  46  through the rigid collar to the fixed member  18 . Although the spokes  58  extend radially, they could extend non-radially if desired. Further, although the spokes are shown to be straight, they could be formed arcuately or otherwise if desired. The bolts  52  threadingly anchor in tapped holes formed in the rigid collar  44 . It should be appreciated that the outer ring of the elastomeric collar may be directly connected to the frame member  18  if desired, thereby eliminating the need for the rigid collar. 
     The elastomeric collar is preferably made of a molded elastomeric material having excellent wear and memory properties, such as a molded polyurethane or other suitable plastic. However, it could be made of a suitable rubber if desired. During molding, the inner ring  62  of the collar is bonded to the steel sleeve  48  to effectively make the collar integral with the sleeve. A plurality of annularly arranged teeth  49 , shown in phantom in FIG. 4, are provided on the outer surface of the sleeve in the area where the inner ring of the elastomeric collar is molded onto the sleeve to enhance the bonding of the collar to the sleeve. A pair of curved or semi-circular rigid bars  54 , against which the heads of the bolts  52  engage, may be used to assist in connecting the elastomeric collar to the rigid collar and avoid any direct contact of the bolt heads against the plastic collar. The bars are preferably made of steel, but it is appreciated that they may be made of any suitable rigid material. 
     As shown in FIG. 4, the depth or thickness of the spokes  58  is less than the depth of or thickness of the rings, although the thickness of the spokes may vary depending on the torsion force desired to be generated on the scraper shaft. While the spokes are disposed adjacent one side edge of the rings, they may be disposed at any suitable location between the side edges of the rings. Further, adjacent spokes may be in one plane as shown or in staggered relation to each other. Preferably, the spokes extend radially in the same plane. A web  51  is provided on the outer radial face of the collar to close the spokes and the openings therebetween and prevent the entry of contaminants that could interfere with the function of the spokes. 
     The outer circumferential wall  60   a  of the outer ring  60  preferably aligns with the outer circumferential edge or wall  44   a  of the rigid collar  44 . The inner ring  62  is bonded to the base of the sleeve  48  at the inner circumference of the ring. The sleeve  48 , which is preferably steel, extends through the elastomeric collar  46  and receives the rotatable shaft  26  for free rotation about the shaft during the tensioning of the elastomeric collar. 
     A plurality of circumferentially spaced apart pin holes  64  provided at the sleeve&#39;s distal end serve to align with a locking bore or hole  65  on the rotatable shaft  26  to permit the locking pin  42  to be inserted and connect the elastomeric collar  46  to the rotational shaft  26  and apply a torsional force to the rotatable shaft  26  so as to produce a biasing force of the scraper blade  22  against the conveyer belt. Each pin hole is preferably diametrically opposed to a second pin hole so that the locking pin can extend through both pin holes and the locking hole to securely lock the sleeve and inner ring to the scraper shaft. Thus, when the elastomeric collar is loaded and the locking pin is inserted, the loading in the elastomeric collar will act to apply a torsional force to the sleeve and scraper shaft to resiliently bias the scraper blade against the conveyor belt. 
     In order to assist in the loading or tensioning of the elastomeric collar  46  and the setting of the locking pin  42  for connecting the elastomeric collar  46  to the rotatable shaft  26 , the sleeve  48  has a plurality of wrench holes or openings  66  inward of the pin holes. A tensioner wrench  70  coacts with the wrench holes to rotate the sleeve for loading the elastomeric collar. While the row of pin holes  64  are directly adjacent the outer or distal end of the collar sleeve  48 , and the row of wrench holes  66  are spaced inward of the row of pin holes, it should be appreciated that the positions of these holes may be reversed. 
     Once the tensioner is assembled and before the locking pin  42  is inserted, the rotatable shaft  26  is rotated in a clockwise direction until the tip or blade edge of the scraper blade  22  engages the surface  28  of the conveyor belt  12 . The tensioner wrench  70  is then mounted on the collar sleeve  48  to rotate the inner ring  62  of the elastomeric collar  46  in a counterclockwise direction. The tensioner wrench  70 , as shown in FIG. 5, includes an elongated lever arm  72  and a head including the prong  68  for insertion into one of the plurality of wrench holes  66  on the sleeve  48  and a bearing tab  74  for bearing on the outer surface of the sleeve  48 . Once the prong  68  is inserted into a wrench hole  66 , the lever arm  72  is rotated counterclockwise, whereupon the head of the lever arm  72  engages the sleeve  48  for rotating the inner ring  62  counterclockwise and loading the elastomeric collar  46 . The sleeve  48  is rotated to apply the desired torsional force to the shaft, and the locking pin  42  is then inserted through a pair of opposed pin holes  64  on the sleeve  48  and through the shaft locking hole  65  on the rotatable shaft  26  to lock the elastomeric collar  46  to the rotatable shaft  26  and scraper blade  22 . The torsion created on the shaft by the elastomeric collar will then act to apply a continuous clockwise torsion bias to the rotatable shaft, thereby maintaining the edge of the scraper blade in biased contact with the conveyor belt surface. 
     While the tensioner is shown at the right end of the scraper shaft, it is appreciated that it may be placed at the left end to apply the torsion force to the scraper shaft. 
     It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is limited only by the scope of the appended claims.