AU2003200698B2

AU2003200698B2 - A Scraper Blade

Info

Publication number: AU2003200698B2
Application number: AU2003200698A
Authority: AU
Inventors: R Todd Swinderman
Original assignee: Martin Engineering Co
Current assignee: Martin Engineering Co
Priority date: 1999-03-19
Filing date: 2003-02-27
Publication date: 2004-09-30
Anticipated expiration: 2020-03-17

Description

I

S&F Ref: 500740D1

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Martin Engineering Company One Martin Place Neponset Illinois 61345-9766 United States of America R Todd Swinderman Spruson Ferguson St Martins Tower,Level 31 Market Street Sydney NSW 2000 (CCN 3710000177) A Scraper Blade The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845c A SCRAPER BLADE Background of the Invention The present invention is directed to a scraper blade that provides a constant cleaning angle with a conveyor belt and that is resiliently biased into cleaning engagement with the conveyor belt by a tensioner mechanism.

Conveyor belts transport various types ofbulk material such as sand, coal, grain and ores.

Conveyor belt cleaners remove conveyed material that continues to adhere to the rotating conveyor belt after the remainder of the conveyed material has been discharged. A scraper blade of a conveyor belt cleaner can be orientated with respect to the surface of the conveyor belt at an o0 obtuse or negative angle, which is referred to as a "peeling" angle, or the scraper blade can be orientated at an acute or positive angle with respect to the conveyor belt which is referred to as a "scraping" angle. It has been found that scraper blades used in connection with conveyor belts conveying certain bulk materials with fines, such as ores, clean the conveyor belt more efficiently when the scraper blades are orientated at a peeling or negative angle with respect to the conveyor i/ belt, rather than at a scraping or positive angle.

Current belt cleaners that have scraper blades disposed at a peeling angle are prone to vibrate or chatter against the belt which lowers the cleaning efficiency of the belt cleaner and can cause damage to the conveyor belt and to the belt cleaner. Another problem with peeling angle scraper blades is that the scraper blades must be precisely aligned with the belt to avoid damaging the belt, and it is difficult to achieve the desired belt to scraper blade contact during installation of a conveyor belt cleaner. Belt damage usually results when one corner of a scraper blade is in engagement with the conveyor belt rather than the entire scraper blade contact area.

A problem that is encountered by both peeling angle and scraping angle conveyor belt cleaners is the tendency of the conveyor belt cleaner or the belt to becone damaged when the conveyor belt reverses direction or "rolls back" momentarily. Conveyor belt reversal or rollback happens frequently when the conveyor belt goes through a normal shutdown sequence, The belt thereafter rolls backward frm a few inches to a few feet as the belt tension relaxes. This roll back motion tends to catch the scraper blade, truing the blade backward and bending the arm on which the scraper blade is mounted, or otherwise causing the scraper blade to swivel out of alignment.

t0 Sometimes the scraper blades do not swivel back into their original cleaning position when the onveyor belt is restarted, or the damage is so severe to the arm that the belt cleaner no longer functions. Even worse is the potential fbr damaging the belt when itzresumes fbrward motion if the scraper blade is locked in a position where only a corner of the scraper blade is in engagement against the belt.

The preferred peeling angle or scraping angle with which a scraper blade engages the conveyor belt varies depending upon the type or grade of materials that are being conveyed.

Conveyor belt cleaners are typically designed fbr operating optimally at a single peeling angle or scraping angle and are not adjustable to provide changes in peeling angle or scraping angle to accomnxxiate changes in the type or grade of conveyed material.

Conveyor belt cleaners have also required the use of external tensioners that include a rubber or elastonuric torsion mnember that is twisted to store a rotational biasing tbree which pivots the scraper blades into biased engagemnent with the conveyor belt. These external tensioners add expense to the conveyor belt cleaner, and if the external tensioner fails, all of the scraper blades of the conveyor belt cleaner will fall away from,4 and out of cleaning engagement with, the conveyor belt. External tensioners also often need to be re-tensioned during the life of the scraper blades as they provided a non-linear output force over their range of operation.

It is the object of the present invention to substantially overcome or at least ameliorate one or more of the disadvantages of the prior art.

Summary of the Invention Accordingly, in a first aspect, the present invention provides a scraper blade for a conveyor belt cleaner including: a blade base having a first end, a second end, and a scraping element located at l0 said first end; and a wear-in tip attached to said first end of said blade base, said wear-in tip including a scraping edge adapted to engage a conveyor belt, said wear-in tip adapted to prevent damage to the conveyor belt regardless of the angle of attached of said scraper blade.

In a further aspect, the present invention provides a scraper blade for a conveyor belt cleaner including: a blade base; a scraping element attached to said blade base, said scraping element including an outer end adapted to engage a conveyor belt, said scraping element being formed from a metal material; and a wear-in tip substantially enclosing said outer end of said scraping element, said wear-in tip being formed from a material that is relatively less wear-resistant than said metal material from which said scraping element is formed.

In a further aspect, the present invention provides a scraper blade for a conveyor belt cleaner including: a mounting base; and a scraping tip attached to said mounting base, said scraping tip including an outer end and a wear resistant scraping element at said outer end of said scraping tip, said scraping element including a wear-in tip comprising a curved scraping end adapted to engage a conveyor belt, said curved scraping end of said wear-in tip adapted to prevent damage to the conveyor belt regardless of the angle of attack of said scraper blade.

3 [R:\LIBTT]03246.doc:hxa Brief Description of the Drawing Figures A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a side elevational view of one embodiment of the scraper blade and gas spring tensioner assembly shown with a new scraper blade.

Figure 2 is a side elevational view of the conveyor belt cleaner and gas spring tensioner assembly of Figure 1 shown with a worn scraper blade.

3a [R:\LIBTT]03246.doc:hxa Figure 3 is a top plan view of the conveyor belt cleaner of the conveyor belt cleaner and gas spring tensioner assembly.

Figure 4 is a side elevational view of the conveyor belt cleaner taken along line 4-4 of Figure 3.

Figure 5 is a top plan view of a mounting member of the conveyor belt cleaner.

Figure 6 is a side elevational view taken along line 6-6 of Figure Figure 7 is a top plan view of the arm member of the conveyor belt cleaner.

Figure 8 is a side elevational view of the arm and blade member of the conveyor belt cleaner.

/0 Figure 9 is a front elevational view of the scraper blade of the conveyor belt cleaner.

Figure 10 is a side elevational view taken along line 10-10 of Figure 9, Figure II is a partial cross-sectional view of the gas spring tensioner.

Figure 12A is a side elevational view of a modified embodiment ofa scraper blade shown in a first peeling angle with respect to a conveyor belt.

Figure 12B is a side elevational view of the scraper blade of Figure 11 shown ina second peeling angle with respect to the conveyor belt.

Figure 13 is a side elevational view of the scraper blade of Figure I I shown in a scraping angle with respect to the conveyor belt.

Figure 14 is an enlarged partial cross-sectional view of the scraping tip of the modified embodiment of the scraper blade.

Figure 14A is an enlarged partial cross-sectional view of a modified scraping tip.

Figure 15 is a perspective view of the conveyor belt cleaner of a modified embodiment of a conveyor belt cleaner and gas spring tensioner assembly.

Figure 16 is a front elevational view of the modified embodiment of the conveyor belt cleaner and gas spring tensioner assembly including the conveyor belt cleaner as shown in Figure Figure 17 is a side elevational view of the conveyor belt cleaner and gas spring tensioner ,I assembly.

Figure 18 is a side elevational view of the conveyor belt cleaner and gas spring tensioner assembly shown with a new scraper blade.

Figure 19 is a side elevational view of the conveyor belt cleaner and gas spring tensioner assembly shown with a worn scraper blade.

Figure 20 is a schematic diagram illustrating how the cleaning angle of the scraper blade of the present invention is determined, Detailed Description of the Preferred Embodiments As shown in Figures 1 and 2, the conveyor belt cleaner and tensioner assembly 30 is attached to and supported by an elongate cross shaft 32. The cross shaft 32 is a tubular member, such as a circular pipe, that /4 includes a generally circular longitudinal bore 34 extending between the ends of the cross shaft 32. The cross shaft 32 and the bore 34 include a longitudinal central axis 36, The cross ulo ft32 is preferubly mounted at each end to a respective stationary structure such as a conveyor chute.

The cross shaft 32 is mounted to the stationary structure such that the cross shaft 32 may be selectively rotated about the central axis 36 and may be selectively locked in place to prevent rotation about the central axis 36. Alternatively, the cross shaft 32 can be mounted to be linearly adjustable.

The conveyor belt cleaner and tensioner assembly 30 is shown in Figures I and 2 in engagement with a moving conveyor belt 38 having an outer surface 40. The belt 38 illustrated in Figures 1 and 2 is moving in a left to right direction as indicated by the arrow or pointed end of the conveyor belt 3 8. The conveyor belt cleaner and tensioner assembly 30 many be used as a I" secondary cleaner, such as shown in Figures 1 and 2, wherein the conveyor belt cleaner and tensioner assembly 3 0 engages the return run of the conveyor belt 3 8, or the conveyor belt cleaner and tensioner assembly 3 0 nay be used as a primary conveyor belt cleaner wherein the conveyor belt cleaner and tensioner assembly 30 engages the conveyor belt 38 at the head pulley of the conveyor.

/0 The conveyor belt cleaner and tensioner assembly 30 includes a conveyor belt cleaner 44 and a conveyor belt cleaner tensioner 46. The conveyor belt cleaner 44, as best shown in Figures 3 and 4, includes a mounting base 50 including an upper mounting member 52 and a lower inounting number 54. As best shown in Figures 5 and 6, the upper mounting rnumber 52 includes a generally semi-circular sleeve 56 having a first generally planar end wall 58 and a spaced apart second generally planar end wall 60. The first and second end walls 58 and 60 extend generally parallel to one another and are located in a common plane 62. The sleeve 56 includes a generally semni-circular outer surface 64 and a generally semi-circular inner surflce, 66, each of which extend from the first end wall 58 to the second end wall 60. The sleeve 56 includes a first side wall 68 and a spaced apart and generally parallel second side wall 70. A central axis 72 is located in the 3c plane 62 midway between and generally parallel to the end walls 58 and 60, The outer surface 64 and the inner surface 66 are each fbrmed about a respective radius from the central axis 72.

A pair of spaced apart and generally parallel bores 74 extend from the first end wall 58 through the outer surface 64 in a direction generally perpendicular to the first end wall 58 and the plane 62, A second pair of spaced apart and generally parallel bores 76 extend through the second end 6 wall 60 and the outer surface 64 in a direction generally perpendicular to the second end wall and the plane 62. The bores 74 and the bores 76 are located in a generally rectangular configuration with respect to one another.

The mounting member 52 also includes a mounting lug 8OA and a spaced apart and (generally parallel mounting lug BOB. Each mounting lug 8OA and B includes a first end that is attached to the outer surface 64 of the sleeve 56 and a second end including a generally circular aperture 82. The mounting lug WA is attached to the outer surfce 64 adjacent the first side wall 68 and the mounting lug SOB is attached to the outer surface 64 adjacent to the second side wall The aperture 82 of the mounting lug BOA and the aperture 82 of the mounting lug 80B are /Dconcentrically located about a pivot axis 84. As shown in Figure 6 the pivot axis 84 is generally parallel to the central axis 72 and is located at an angle of approximately 67,50* to the plane 62 as mecasured about t central axis 72.

The lower mounting member 54 of the mounting base 50 is constructed substantially identical to the upper rnounting member 52. As shown in Figure 4, the lower mounting member j( 54 includes a generally semi-circular sleeve 86 and a pair of mounting lugs 88A and B that are attached to the sleeve 86. Each mourning lug SSA and B includes a circular aperture 90. Each aperture 90 is concentrically located about a pivot axis 92 that is generally parallel to the central axis 72. The pivot axis 92 is located at an angle of approximately 67.5' to the plane 62 as measured about the central axis 72.

As best shown in Figures I and 2, the upper mounting member 52 and the lower mounting member 54 are placed around the cress shaft 3 2 such that the inner surftce 66 of t mounting mrembers 52 and 54 engage the outer sufae of the cross shaft 32. The end walls 58 and 60 of the respective mnounting members 52 and 54 are spaced slightly apart from one another, Fasteners extend through the bores 74 and 76 in the upper mounting mnember 52 and through the bores 74 and 76 in the lower mounting member 54. The faisteners tighten and clamp the upper mounting member 52 and the lower mounting member 54 to the cross shaft 3 2 such that the mourning base is stationarily clamped to the cross shaft 32 fbr conjoint rotation with the cross shaft 32. The nxunting base 50 does not rotate with respect to the cross shaft 3 2. As shown in Figure 1, the 4' upper mounting member 52 is connected to the lower mounting member 54 such that the apertures 82 in the mounting Jugs 8OA and B and the pivot axis 84 are located at an angle of approximately 135S to the apertures 90 of the mounting lugs 88A and B and the pivot axis 92 as measured about the axis 3 6.

The conveyor belt cleaner 44 also includes an arm and blade assembly 98 as shown in Figure 8 having an arm member 100 and a scraper blade 102 that is pivotally attached to the ar-m member 100, As best shown in Figures 7 and 8, the arm member 10O includes an elongate shaft 104 having a longitudinal central axis 106, The shaft 104 comprises a tubular member having a longitudinal bore 105. The outer end of the shaft 104 includes a threaded bore 107 located concentrically along the axis 106. A bracket 108 is attached to the outer end of the shaft 104 and extends radially outwardly from the shaft 104. The bracket lO8 includes a tab 109 that projects outwardly beyond the outer end of the shaft 104 in a direction parallel to the axis 106. The bracket lOB also includes a threaded bore 110 that is in commnunication with the threaded bore 107 and that is generally perpendicular to the axis 106. A threaded set screw is located in the bore 110.

A tubular sleeve 112 is attached transversely to the second end of the shaft 104. The tubular sleeve 112 includes a generally circular bore 114 having a central longitudinal axis 116.

A stop shaft member 118 is attached to the tubular sleeve 112 and extends outwardly from the tubular sleeve 112 co ncentrically along the axis 106 to an outer end 120. The stop member 118 is attached to the tubular sleeve 112 on a diametrically opposite side 6Dmr the shaft 104. The stop number 118 may include a set screw or other adjustment mechanism for adjusting the gap between the stop member 11t8 and the sleeve 112 to accommodate diffrent mounting positions and blade configurations. A pair of spaced apart and generally parallel mounting tugs 1 22A and B are attached to the shaft 104. Each mounting lug 122A and B includes an aperture 124. The /apertures 124 in the mounting lugs l22A and B are concentrically located about a pivot axis 126, The pivot axis 126 is generally parallel to the axis 11 6, As shown in Figures 3 and 4, the arm member 100 is pivotally conniected, to the mounting base 50 fbr pivotal movement about the pivot axis 84. The tubular sleeve 112 of the arm member 100 is located between the mounting lugs BOA and 8OB of the upper mounting member 52 such Io that the bore 114 is aligned with the apertures 82 and such that the axis 116 is generally coaxial with the pivot axis 84. A generally cylindrical pin 128 exends through the apertures 82 in the mounting tugs BOA and B and through the bore Il4 oftic sleeve 11 lto pivotally connect the arm member 100 to the mounting base 50 for selective pivotal movement about the pivot axis 84 and the coaxial axis 116. The pin 128 is preferably nade from a metal such as bronze. The arm member 100 is preferably nude from a metal such as steel.

The scraper blade 102 of the arm and blade assembly 98 as best shown in Figures 9 and is generally trnud as a curved plate. The scraper blade 102 includes a mounting base 130 having an aperture 132 that is adapted to be aligned with the threaded bore 107 in the end of the shaft 104 of the arm nember 100. The mounting base 130 also includes an open-end slot 13 1 in .2A' the bottom end of the mounting base 130. The slot 131 includes opposing aide walls 133A and B that are disposed at an angle, such as fifteen degrees, to one another. The slot 131 is adapted to receive the tab 109 of the bracket 108 of the ann 100. The scraper blade 102 includes a scraping tip 134 attached to the mounting base 130. The scraping tip 134 includes a wear resistant scraping element 13 5 that way be lbnncd from tungsten carbide, a ceramic material or the like. The scraper blade 102 includes a generally concave inner surface 136 that is shaped to confbnn generally to an arc of a circle, The inner surface 136 extends fr-om the top end of the scraping tip 134 to the bottom end of the mounting base 130. The scraper blade 102 also includes a generally convex outer surface 138 that conforms generally to an arc of a circle. The'Outer I surface 138 is generally spaced equidistantly frin the inner surface 136. The inner surface 136 and the outer surface 13 8 are both formed as an arc of a circle wherein each circle has the same center point, with the center point being located on the coaxial axes 84 and I116. The inner surface 136 and the outer surface 138 are each fbrmed by a respective radius extending from the coaxial axes 84 and 116. In one configuration of the scraper blade 102 the inner surface 136 is as an arc of a circle having a radius of approximately 245.4 millimeters and the outer surface [3 8 is fbrmned as an arc of a circle having a radius of approximately 257.9 millimeters, wherein each radius originates from the same center point on the pivot axis 84.

The scraping tip 134 includes a generally planar end wall 140 that extends from the outer surface 13 8 to the scraping element 13 5. The outer edge of the scraping element 13 5 forms a iC generally linear scraping edge 142 at the upper end of the inner surface 136. The end wall 140 is located at an angle of approximately 135' with respect to a plane 144 that extends through the scraping edge 142 and the bottom edge of the inner surface 136 as mneasured about the scraping edge 142. The scraper blade 102 includes a first side wall 146 and a spaced apart and generally parallel second side wall 148. The mounting base 130 of the scraper blade 102 includes a .x generally planar and circular recess 149 located at each end of the aperture 132, respectively fbrmed in the inner surface 236 and the outer surface 138. A bushing 152 having a circular aperture 15 1 is located in the aperture 13 2.

As best shown in Figure 8, the scraper blade 102 is removably and pivotally attached to the outer end of the shalt 104 of the arm mentor 100 by a fastener I50, such as a bolt that exiends through the aperture 132 and the aperture 151 in the bushing 152 such that the scraper blade 102 can pivot or swivel about the axis 106 and about the shank of the fastener 150 with respect to the arm member 100, The set screw in the bore 110 is fastened against the shank of the fhstener 150 to prevent the fistener 150 florn rotating about the axis 106, The scraper blade 8 102 can swivel approximately 7,5* about the axis 106 in either direction from a neutral position wherein the tab 109 is located within the slot 131 rnidway between the side walls lI33AandB, fix a total Of 150* of movement. The scraper blade 102 can pivot or swivel about the axis 106 until the side wall 1 33A or 133B1 engages the tab 109. The scraper blade 102 van thereby swivel about the axis 106 within limits to align with the surface 40 of the belt 38 and to adjust to changes in (0the configuration of the belt 38S.

The scraper blade 102 is preferably mounted to the an-n member 100 such that the respective circles or radii that fbrm. the inner surface 136 and the outer surface 138 have a conmmon center point located on the pivot axis 84. The inner surilice 136 and the outer surface 13 8 will theretbre both maintain a co nstant a ngle o f cleaning engagement with the outer su rtce of the conveyor belt 3 8 as the scraping tip 13 4 of the scraper blade 102 wears due to its engagement with the rotating belt. The scraper blade 102 may be Made from a metal, such as T- I steel or tungsten-carbide, a ceramic material, or an elastonieric material such as urethane.

The conveyor belt cleaner tensioner 46 as shown in Figure 11 includes a generally cylindrical housing 156 having an elongate generally cylindrical cavity formed therein. A tamounting lug 158 having an aperture formed therein is attached to a first end ofthe housing 156.

An elongate generally cylindrical ram 160 has a first end located within the cavity of the housing 156 and a second end which projects outwardly from the housing 156. The first end of the ram 160 slidably engages the wall of the cavity and includes a valve. A mounting lug 162 including a generally circular aperture is attached to the second end of the ram 160. The ram 160 includes a central longitudinal axis 164. The central axes of the apertures in the mounting Jugs 158 and 162 are generally parallel to one another and extend through the central axis 164. The ram 160 is slidable with respect to the housing 156 along the central axis 164 such that the ram 160 is selectively extendable, wherein the nounting lug 162 is moved away from the housing 156, and such that the ram 160 is selectively retractable, wherein the nxounting lug 162 is moved closer to the housing 156, The mounting lug 158 ofihe housing 156 is pivotally attached to the mounting lugs 122A and B of the arm member 100 by a generally cylindrical pin 170. The pin 170 extends through the apertures 124 in the mounting tugs i2ZA and B and the aperture in the mounting lug 158.

The tensioner 46 is thereby pivotatly moveable with respect to the armn and blade assembly 98 about the pivot axis 126, The mounting lug 162 of the ram 160 is pivotally attached to the mounting lugs 8SBA and B of the lower mounting member 5 4 by a generally cylindrical pin 172, The pin 172 extends through the apertures 90 in the mounting lugs 88A and B and the aperture in the mounting lug 162. The tensioner 46 is thereby pivotally moveable with respect to the mounting base 50 about the pivot axis 84. The pins 170 and 172 are preferably made from netl such as brass. As best shown in Figures I and 2, the pivot axes 84, 92 and 126 are generally parallel to one another and are located in a generally triangular position with respect to one another.

A preferred conveyor belt cleaner tensioner 46 is a hydropneurnatic linear actuator .4commonly referred to as a gas spring tensioner as shown in Figure I I that has an approximately linear relationship between the position of the ram 160 and the tree output. A preferred gas spring tensio ner is manufactured by AVM under Model No. AHP 6240. A gas spring tensioner provides a nearly constant linear frce output between a first fully retracted position of the rain 160 and a second fully extended position of the ram 160. The approximately constant magnitude 12 of force provided by the gas spring tensioner 46, in combination with the configuration of the scraper blade 102 and the manner in which the scraper blade 102 is connected to the arm member 100 fir pivotal movement about the pivot axis 84, enables the scraper blade 102 to engage the conveyor belt 3 8 with an approximately constant cleaning pressure between the scraper blade 102 and the outer surface 40 of the conveyor belt 3 8 over the wear life of the scraper blade 102. The tensioner 46 may alternatively comprise an electromagnetic actuator or a constant fbrce mechanical spring which provide a generally constant output force over their operating range.

The gas spring tensioner 46 includes a compressed gas 166, such as nitrogen, and liquid 168, such as hydraulic oil, located within the cavity of the housing 156. The liquid 168 fUnctions /0 to dampen the movement of the ram 160. Dampened movement of the ram 160 with respect to the housing 156 reduces the vibration or chatter ofthe scraper blade 102 against the conveyor belt 38 that scraper blades orientated at a peeling angle are otherwise generally prone to generate, As the gas spring tensioner 46 dampens the tendency of the scraper blade 102 to vibrate, the scraper blade 102 can be used over a large range of different peeling angles. The scraper blade 102 may 14' therefore be used at the optimum cleaning angle fbr a particular set of conditions as determined by variables such as belt speed, belt condition anid the type ofnmaterial conveyed. The run 160 in the gas spring tensioner 46 has a time reaction constant that is significantly longer than that of the rubber or elastomeric torsion springs that have typically been used fur tensioning secondary conveyor belt cleaners. The conveyor belt cleaner 44 is therefore much less likely to be adversely 0 J affected by conveyor belt roll back than are conveyor belt cleaners that are tensioned by torsion springs. As shown in Figures I and 2, the scraper blade 102 is orientated at a 45 0 negative peeling angle with respect to the conveyor belt 38. In applications where belt roll back is a problem, the prefbntd cleaning angle is a scraping angle.

In operation, the cross shaft 32 is mounted at a desired position with respect to the conveyor belt 38 in order to place the scraper blade 102 at the desired cleaning angle with respect to the belt 38. The upper munting member 52 and the lower ounting member 54 are then placed around the cross shaft 32 and are fastened to one another such that the mounting members 52 and 54 are securely affixed to the cross shaft 32. Alternatively, the mounting lugs 80A and B and the mounting lugs 88A and B can be connected directly to the cross shaft 32 by welding or the like if so desired. The cross shaft 32 is rotated about the axis 36 to engage the scraper blade 102 against the belt 38, Continued rotation of the cross shaft 32 compresses the ram 160 of the gas spring tensioner 46 into the housing 156 such that the ram 160 biases the scraper blade 102 ID into engagement with the belt 38. Alternatively, the cross shaft 32 can be adjusted linearly to compress the ram 160. The cross shaft 3 2 is then locked in place such that the cross shaft 32 will not rotate about the axis 36 after the initial desired compression of the gas spring 46. The gas spring tensioner 46 is typically compressed until approximately ten millimeters of the ram 160 is showing.

As shown in Figure 1, the conveyor belt cleaner 44 includes a new scraper blade 102. The gas spring tensioner 46 exerts a resilient biasing fbrce against the arm member 100 and attempts to pivot the arm and blade assembly 98 in a counter-clockwise direction as shown in Figure 1 about the pivot axis 84, The gas spring tensioner 46 thereby resiliently biases the scraping edge 142 of the scraper blade 102 into engagement with the conveyor belt 38 with a desired amount o- of force. As the scraping tip 134 of the scraper blade 102 wears due to its engagement with the rotating belt 38, the gas spring tensioner 46 will pivot the scraper blade 102 about the pivot axis 84 into continuing biased engagerment withthe conveyor belt 3B. The gas spring tensioner46 will bias the scraper blade 102 into continuing engagement with the conveyor belt with approximately the same amount of force over the life of the scraper blade 102, As the inner surface 136 and outer surface 13 8 of the scraping tip 134 are equally spaced apart from one another, such that the scraping tip 13 4 has a relatively constant thickness and width, the magnitude of the pressure with which the scraping tip 13 4 engages the conveyor belt 3 8 will also remain approximately constant over the wear life of the scraper blade 102.

'C As best shown in exaggerated scale in Figure 2, once the scraping tip 13 4 of the scraper blade 102 has been worn to the point where the scraper blade 102 requires replacement, the stop shaft nember 118 of the ann member 100 engages the outer surface of the mounting member 52 to prevent the arm member 100 arnd scraper blade 102 from pivoting any further in the counterclockwise direction as shown in Figure 2 about the pivot axis 84. The stop shaft member 118 thereby prevents the ann number 100 and fastener 150 from being pivoted into engagemnt with the conveyor belt 38. Once the scraper blade 102 is filly worn as shown in exaggerated scale in Figure 2, the cross shaft 32 can be rotated about the axis 36 to pivot the conveyor belt cleaner 44 and the scraper blade 102 away from the co nveyor belt 3 8. The fastener 150 can then be removed to allow the renoval and replacement of the scraper blade 102.

The pivot axis 84, about which the scraper blade 102 pivots, may be placed in various different positions with respect to the outer surface 40 of the conveyor belt 38 as desired in order to provide a desired cleaning angle between the scraper blade 102 and the outer surface 40 of the belt 3 8. The scraper blade 102 can be used in a peeling angle or in a scraping angle as desired.

The arcuate configuration of the scraper blade 102Z and its orientation with respect to thepivot .x axis 84 about which the scraper blade 102 pivots, provides a constant cleaning angle between the scraper blade 102 and the conveyor belt 3 8 no matter at what distance the conveyor belt cleaner 44is mounted from the conveyor belt 38. When the pivot axis 84 is located vertically highr than the point where the central axis 106 intersects the inner surface 136 of the scraper blade 102, the scraper blade 102 is positioned in a positive scraping angle with respect to the conveyor belt 38.

is T I When the pivot axis 84 is located vertically lower than the point of intersection between the pivot axis 106 and the inner surface 136 of the scraper blade 102, the scraper blade 102 is positioned at a negative peeling angle with respect to the conveyor belt 38.

Figure 20 schenmtically illustrates how the conveyor belt cleaner and tensioning assembly 4" 3.0 can be selectively positioned with respect to the outer surface 40 of the conveyor belt cleaner 44- to place the scraper blade 102 at the desired cleaning angle with respect to the belt 3 8. As shown in Figure 24, the inner surface 136 and scraping edge 142 of the scraper blade 102 are located at a radius A from the pivot axis 84. The inner surface 136 is fbrncnd as an arc of a circle having a radius The cleaning angle of the scraper blade 102 with respect to the surface 40 of the conveyor belt 3 8 is the angle D between the surface 40 of the conveyor belt 3 8 and a plane 176 that extends through the intersection of the scraping edge 1.42 and the surface 40 and that is tangent to the inner surface 13 6. The angle E as shown in Figure 24 is equal to the cleaning angle D. The angle E is between a radius F that extends from the pivot axis 84 to the point of intersection between the scraping edge 142 and the surface 40 of the conveyor belt 3 8, and a line It G that extends through the pivot axis 84 and that is generally perpendicular to the surface 40. The radius A is equal in length to the radius F. As the length of the radius A is known ibr a particular conveyor belt cleaner and tensioning assembly 30, the distance B at which the pivot axis 84 must be placed from the surface 40 of the conveyor belt 3 8 to obtain the desired angle E, which corresponds to the desired cleaning angle D, can be determined through trigonometric equations, .1 such as cosine E equals B divided by F. The distance C can also be determined through trigonometric equations such as sine E equals C divided by F, As an example, if the distance B is equal to the distance C, the angle E and the angle D are both equal to 450.

A plurality of conveyor belt cleaner and tensioner assemblies 30 may be connected to the cross shaft 3 2 adjacent to one another. As each conveyor belt cleaner 44 has its own conveyor !3 I belt cleaner tensioner 46, the failure of one tensioner 46 will not afliect the cleaning ability of the remaining conveyor belt cleaners 44 that are mounted on the cross shaft 32.

A modified embodiment of the scraper blade 102 is shown in Figures 12A-IIA as indicated by the reference numiber 180. The scraper blade 180 includes a concave inner surface .(182 and a convex outer surface 184 that are configured in the samie mnanner as the inner and outer surfaces 13 6 and 13 8 of the scraper blade 102. The scraper blade 190 includes a blade base 186 that extends from a first end 188 to a second end 190. The base 186 is preferably nude from a mietal such as mild steel or stainless steel but can be made from an elastomeric miaterial such as urethane, One or more wear-resistant scraping elemrents 192 are attached to the base 186 at the IV first end 188. The scraping elements 192 form a portion of the inner surface 182. The scraping elements 192 may be made frnm a wear- resistant material such as tungstn-carbide, or ceramic 1 materials. The scraping elements 19 2 extend along the ba se 186 fro m a first end 19 4 to a second end 196. The scraping elements 192 extend across the entire width of the scraper blade 180.

A wear-in tip 2 00 is attached to the first end 194 of the scraping elements 192 and to the S first end 188 of the base 186. The wear-in tip 200 includes a scraping edge 202. The wear-in tip 200 also includes a first leg 204 that extends downwardly from the first end 194 of the scraping elements 192 alorngthe inner surface 182. The wear-in tip 200 also includes a second leg 206 that extends downwardly along the outer surface 184 of the base 186. The wear-in tip 200 thereby encloses the first end 194 of the scraping elements 192 and the first end 188 of the base 186. The 2 wear-in tip 200 is preferably formed from a material that is considerably less wear resistant than the material that form the scraping elements. One preferred material is an elatomneric material such as urethane having a durometer such as 70 Shore D. The urethane material is bonded to the metal scraping elements 192 and me-tal. base 186. The wear-in tip 200 may alternatively be made 1 1 A from a metal material such as bronze or lead, alloys of silver, copper, tin or lead, or materials of low abrasion such as adhesives or filled epoxies. The alloys may be applied as a solder, Figure 12A shows the scraper blade 180 positioned at a thirty degree negative cleaning angle with respect to the conveyor belt 38. Figure 129 illustrates the scraper blade 180 positioned at a fbrty-five degree negative cleaning angle with respect to the conveyor belt 38.

Figure 13 illustrates the scraper blade 180 positioned at 2.7 0 positive cleaning angle with respect to the conveyor belt 38. The scraper blade 180 can be used at various other negative or positive cleaning angles as desired.

The wear-in tip 200 of the scraper blade 180 allows the scraper blade 1 80-to be installed tO at any cleaning angle and to allow the scraping tip to wear in before the wear-resistant scraping elements 192 engage the conveyor belt 38. The wear-in tip 200 thereby eliminates the potential damage that is sometimes caused to conveyor belts 38 when just a portion of a new scraper blade is engaging the conveyor belt, rather than the whole width of the scraper blade. The wear-in tip 200 of the scraper blade 180 eliminates this problem as the wear-in tip 200 will not damage the K' belt 38 if the scraper blade 180 is initially misaligned with the belt.

Figure 14A shows a modified embodiment of the scraper blade 180' wherein the first end 194' of the scraping element 192' is formed in a serni-circular shape, as opposed to a planar shape as shown in Figure 14. The curved semi-circular shape of the first end 194' is a wear-in tip 200' that will prevent damage to the belt when the first end 194' initially engages the belt, regardless 0.0 of the angle of attack of the scraper blade 180! A modified embodiment of the conveyor belt cleaner and tensioner assembly 30 is shown in Figures 15-19 as conveyor belt cleaner and tensioner assembly 220. The conveyor belt cleaner and tensioner assembly 220 is adapted to be removably mounted to the cross shaft 32, The conveyor belt cleaner and tensioner assembly 220 includes a conveyor belt cleaner 222, a pair of 18 1 1 mounting bases 224A and B and a conveyor belt cleaner tensioner 226. The tensioner 226 is constructed essentially identically to the tensioner 46 and preferably comprises a gas spring tensioner.

The mounting bases 224A and B each include a first generally semi-circular mounting C sleeve 230 and a second generally semi-circular mounting sleeve 232. The second mounting sleeve 232 includes an outwardly extending lug 234 having a generally circular aperture 236. The second mounting sleeve 232 is removably attached to the first mounting sleeve 230 by a plurality of fasteners 23 8 in the same manner that the mounting members 52 and 54 are removably attached to one another. The mounting bases 224A and B are stationarily clamped to the cross shaft 32 I/J such that the mounting bases 224A and B do not rotate with respect to the cross shaft 32.

The conveyor belt cleaner 222 includes a mounting base 244, an arm member 246 and a scraper blade 248, The mounting base 244 includes a first generally semi-circular mounting sleeve 250 and a second generally semi-circular mounting sleeve 252. The first and second mounting sleeves 250 and 252 are connected to one another around the cross shaft 32 by fasteners in the same mnner as the mounting sleeves 230 and 232. However, the mounting base 244 formed by the connected mounting sleeves 250 and 252 is rotatable with respect to the cross shaft 32.

The arm member 246 has a generally inverted U-shape with opposing side walls. The arm member 246 includes a mounting plate 256 at a first end and is attached at a second end to the second mounting sleeve 252. The scraper blade 248 is removably attached to the mounting plate 256 at the first end of the arm member 246 by one or more fasteners 258, The scraper blade 248 is formed similar to the scraper blade 102, The scraper blade 248 is connected to the arm member 246 and the mounting base 244 such that the center or origin of the radius that forms an arcuate inner surface 260 of the blade 248, and the common center or origin of the radius that forms the I 4 arcuate outer surface 262 of the scraper blade 248, are located on the axis 36. The arm rrwmber 246 and the scraper blade 248 are pivotal about the central axis 36.

The tensioner 226 is partially located within the U-shaped arm member 246 between the side walls, The tensioner 226 is pivotally conniected to the lugs 234 of the mounting bases 224A 4' and B by a pin 266, and the opposite end of the tensioner 226 is pivotally connected to the arm member 246 by a pin 268, The mounting base 244 of the conveyor belt cleaner 222 is located adjacent to and between the mounting bases 224A and B, Figure 18 shows the conveyor belt cleaner and tensioner assembly 220 attached to the cross shaft 3 2 with a new scraper blade 248 in cleaning engagement with the conveyor belt 3 8, /0 As shown in Figure 19, as the scraper blade 248 weans, the ram of the gas spring tensioner 226 extends from the housing of the tensioner 226 and pivots the arm member 246 and scraper blade 248 about the axis 36 to maintain the scraper blade 248 in biased engagement with the outer surface 40 of the conveyor belt 3 8.

1Various features ofthe invention have been particularly shown and described in connection I' with the illustrated embodiments of the invention, however, it must be understood that these particular arrangements merely ilustrate, and that the invention is to be given its fulest interpretation within the terms of the appended claims.

Claims

1. A scraper blade for a conveyor belt cleaner including: a blade base having a first end, a second end, and a scraping element located at said first end; and a wear-in tip attached to said first end of said blade base, said wear-in tip including a scraping edge adapted to engage a conveyor belt, said wear-in tip adapted to prevent damage to the conveyor belt regardless of the angle of attack of said scraper blade.

2. The scraper blade of claim 1 wherein said blade base includes a lo generally arc-shaped inner surface and a generally arc-shaped outer surface.

3. The scraper blade of claim 1 wherein said wear-in tip substantially encloses an outer end of said scraping element.

4. The scraper blade of claim 1 wherein said wear-in tip includes a first leg and a second leg, said first and second legs being disposed on opposite sides of said scraping element.

The scraper blade of claim 1 wherein said wear-in tip is formed from a material selected from the group consisting of elastomers, lead, bronze, silver, copper, tin or epoxies.

6. The scraper blade of claim 1 wherein said blade base includes an aperture having a central axis about which said scraper blade is adapted to pivot and a slot having a pair of side walls which are adapted to limit pivotal movement of said scraper blade.

7. A scraper blade for a conveyor belt cleaner including: a blade base; a scraping element attached to said blade base, said scraping element including an outer end adapted to engage a conveyor belt, said scraping element being formed from a metal material; and a wear-in tip substantially enclosing said outer end of said scraping element, said wear-in tip being formed from a material that is relatively less wear-resistant than said metal material from which said scraping element is formed.

8. The scraper blade of claim 7 wherein said wear-in tip is formed from a material selected from the group consisting of elastomers, lead, bronze, silver, copper, tin, or epoxies. 21 [R:\LIBTT]03246.doc:hxa

9. The scraper blade of claim 1 wherein said scraping element is formed from a wear-resistant material and said wear-in tip is formed from a material that is less wear-resistant than said wear-resistant material of said scraping element.

A scraper blade for a conveyor belt cleaner including: a mounting base; and a scraping tip attached to said mounting base, said scraping tip including an outer end and a wear resistant scraping element at said outer end of said scraping tip, said scraping element including a wear-in tip comprising a curved scraping end adapted to engage a conveyor belt, said curved scraping end of said wear-in tip adapted to prevent 1o damage to the conveyor belt regardless of the angle of attack of said scraper blade.

11. A scraper blade for a conveyor belt cleaner, substantially as herein described with reference to any one of the embodiments of the invention shown in the accompanying drawings. Dated 5 August, 2004 Martin Engineering Company Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON 22 [R:\LLBTT]03246.doc:hxa