Patent Publication Number: US-9422812-B2

Title: Cutting tool mounting assembly with elastomeric coated bushing

Description:
BACKGROUND OF THE INVENTION 
     The invention pertains generally to a cutting tool mounting assembly that is useful in association with machines for impinging a substrate or earth strata such as, for example, asphaltic roadway material, coal deposits, mineral formations and the like. More particularly, the invention pertains to a cutting tool mounting assembly as well as the individual components of such assemblies. 
     One typically uses such assemblies in conjunction with a rotatable drum or driven member. The driven member rotates in such a fashion to drive the rotatable cutting bit or tool into earth strata to disintegrate the same into smaller pieces including fine particulates, i.e., cutting debris. The cutting bit or cutting tool and the base or support block are each subjected to considerable stresses during mining operations, road milling operations or other like operations that can lead to wear and/or failure of one or more of the cutting tool assembly components. One source of wear occurs as a result of the mounting between the cutting bit or cutting tool and the base or support block and the contact therebetween. Accordingly, there is a desire to mount the cutting bit or cutting tool in the base or support block so as to reduce stress between the components in order to maximize the useful life of all the components of the cutting tool assembly. 
     One solution to minimize such stress and/or wear is to provide a bushing between the cutting bit or cutting tool and the base or support block. Typically, the bushings are press fit into the base or support block which after a long time of operation they can begin to rust together and become very difficult to remove. An alternative to the bushing arrangement is to use a sleeve which is a slip fit into the base or support block and held in with an external retainer. These are easier to remove but cause the base or support block to wear quicker. 
     Thus, it would be highly desirable to provide an improved cutting tool mounting assembly that overcomes disadvantages and shortcomings of heretofore known such assemblies. It would also be highly desirable to provide an improved cutting tool mounting assembly having a bushing arrangement that is easier to remove while still providing the desired protection to the base or support block in comparison to heretofore known such arrangements. 
     SUMMARY OF THE INVENTION 
     In accordance with an aspect of the invention, a cutting tool mounting assembly adapted for attachment to a surface of a rotatable driving member of a cutting tool machine and adapted for receiving a cutting tool includes a base having a bottom portion for attachment to the surface of the rotatable driving member and a front portion that defines a receptacle having an inner wall and a bushing configured for receipt in the receptacle of the base. The bushing includes: a forward face defining an aperture for receiving the cutting tool; a shoulder generally opposite the forward face, the shoulder configured for cooperating with the front portion of the base; and a shank portion extending rearward from the shoulder, the shank portion having an outer surface configured for cooperating with the inner wall of the receptacle. A first elastomeric layer is positioned between the shoulder of the bushing and the front portion of the base and a second elastomeric layer is positioned between the outer surface of the shank portion and the inner wall of the receptacle. 
     In accordance with another aspect of the invention, a cutting tool mounting assembly adapted for attachment to a surface of a rotatable driving member of a cutting tool machine and adapted for receiving a cutting tool includes a base having a bottom portion for attachment to the surface of the rotatable driving member and a front portion that defines a receptacle having an inner wall and a bushing configured for receipt in the receptacle of the base. The bushing includes: a forward face defining an aperture for receiving the cutting tool; a shoulder generally opposite the forward face, the shoulder configured for cooperating with the front portion of the base; and a shank portion extending rearward from the shoulder, the shank portion having an outer surface configured for cooperating with the inner wall of the receptacle. Also included is a first elastomeric layer formed on at least a portion of the shoulder of the bushing and a second elastomeric layer formed on at least a portion the outer surface of the shank portion. 
     In accordance with another aspect of the invention, a cutting tool mounting assembly adapted for attachment to a surface of a rotatable driving member of a cutting tool machine and adapted for receiving a cutting tool includes a base having a bottom portion for attachment to the surface of the rotatable driving member and a front portion that defines a receptacle having an inner wall. An elastomeric coated bushing is configured for receipt in the receptacle of the base. The elastomeric coated bushing includes: a forward face defining an aperture for receiving the cutting tool; a shoulder generally opposite the forward face, the shoulder configured for cooperating with the front portion of the base; and a shank portion extending rearward from the shoulder, the shank portion having an outer surface configured for cooperating with the inner wall of the receptacle. 
     These and other aspects of the present invention will be more fully understood following a review of this specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded isometric view of a cutting tool mounting assembly, in accordance with an aspect of the invention. 
         FIG. 2  is a side view of a bushing shown in  FIG. 1 , in accordance with an aspect of the invention. 
         FIG. 3  is a sectional view along line  3 - 3  of  FIG. 2 , in accordance with an aspect of the invention. 
         FIG. 4  is an enlarged view of a portion of  FIG. 3 , in accordance with another aspect of the invention. 
         FIG. 5  is a sectional view of the bushing as received in a base of the cutting tool mounting assembly, in accordance with an aspect of the invention. 
         FIG. 6  is an additional bushing similar to the bushing shown in  FIG. 3 , in accordance with an aspect of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is for purposes of illustrating various aspects of the invention only and not for purposes of limiting the scope of the invention. 
     Referring to the Figures, there is illustrated a cutting tool assembly or cutting tool mounting assembly, generally designated as reference number  10 , in accordance with various aspects of the invention. As will be apparent following a description of the invention herein, when referring generally to a “cutting tool mounting assembly” adapted for attachment to a surface of a rotatable driving member of a cutting tool machine the invention generally includes a base configured for attachment to the surface of the rotatable driving member, bushing configured for receipt in the base and a cutting tool configured for receipt in the bushing. For simplification of description of the invention herein, these aspects of the invention may be generally referred to as an “assembly.” 
     It will be appreciated that the invention has application to various kinds of cutting tools useful in various kinds of cutting operations. Exemplary operations include, without limitation, road planing (or milling), coal mining, concrete cutting, and other kinds of cutting operations wherein a cutting tool with a hard cutting member impinges against a substrate (e.g., earth strata, pavement, asphaltic highway material, concrete, minerals and the like) breaking the substrate into pieces of a variety of sizes including larger-size pieces or chunks and smaller-sized pieces including dust-like particles. In addition, it will be appreciated that the cutting tool mounting assembly  10  of the invention, and components thereof, may be manufactured in various sizes and dimensions depending upon the desired application of the assembly  10 . 
     Referring to  FIGS. 1-5 , there is illustrated in detail the assembly  10  and various components of the invention. The assembly  10  is adapted for attachment to a surface of a rotatable driving member of a cutting machine (not shown) such as, for example, a mining machine. The assembly  10  is attached or connected to the rotatable driving member such as, for example, a rotating drum by methods well known in the art such as, for example, welding. The assembly  10  is configured for mounting or receiving a cutting tool  12  with a hard cutting member  14  for impinging against a substrate, e.g., earth strata, pavement, asphaltic highway material, concrete, minerals and the like as is well known in the art. 
     The assembly  10  includes a base  16 . The base  16  includes a bottom surface or bottom portion  18  and a front portion  20  that defines a receptacle  22 . The receptacle  22  includes an inner surface or inner wall  24 . 
     The assembly  10  also includes a bushing  26  configured to be received in the receptacle  22  of the base  16 . Typically, the bushing  26  is press fit into the receptacle  22  of the base  16 . In one aspect, the bushing  26  is configured to be releasably received in the receptacle  22  so that the bushing  26  receives most of the impact and wear from the cutting tool  12  during operation and therefore reduces or minimizes wear on the base  16 . Then bushing  26  can be removed and replaced as needed. 
     The bushing  26  includes a forward face  28  that defines an aperture  30  for receiving the cutting tool  12 . In addition, the bushing  26  includes a shoulder  32  generally opposite the forward face  28 . The shoulder  32  is configured for cooperating with the front portion  20  of the base  16 . The bushing  26  also includes a shank portion  34  extending generally rearward from the shoulder  32 . In one aspect, the shank portion  34  has an outer surface  36  configured for cooperating with the inner wall  24  of the receptacle  22  when the bushing  26  is inserted in the receptacle  22 . In another aspect, the shank portion  34  is generally cylindrical. However, the shank portion  34  can be other shapes such as, for example, triangular or quadrilateral as well. 
     The assembly  10  can have a central longitudinal axis A-A that passes centrally through the cutting tool  12 , aperture  30  of the bushing  26  and receptacle  22  of the base  16 . 
     In accordance with an aspect of the invention, the bushing  26  can generally be an elastomeric coated bushing  26  having a first elastomeric layer  38  positioned between the shoulder  32  of the bushing  26  and the front portion  20  of the base  16  and a second elastomeric layer  40  positioned between the outer surface  36  of the shank portion  34  and the inner wall  24  of the receptacle  22  of the base  16 . 
     In one aspect, elastomeric layers  38  and  40  can be constructed from, for example, polyisoprene, a polyisoprene blend, butyl rubber, acryl rubber, polyurethane, flurorubber, polysulfide rubber, ethylene-propylene rubber (EPR and EPDM), Hypalon, chlorinated polyethylene, ethylene-vinyl acetate rubber, epichlorohydrin rubber, chloroprene rubber, silicone, or other heavily damped elastomer. 
     In another aspect, the first elastomeric layer  38  is formed on the shoulder  32  of the bushing  2 . In yet another aspect, the second elastomeric layer  40  is formed on the outer surface  36  of the shank portion  34 . The elastomeric layers  38 ,  40  may be attached to the respective surfaces of the bushing  26  by, for example, chemical bonding, mechanical fixtures or tabs, glues or adhesives, or any suitable type of thermally activated shrink tubing. 
     In another aspect of the invention, the second elastomeric layer  40  can have a variable thickness. In one aspect, the second elastomeric layer  40  can be non-linear. In another aspect, as shown for example in  FIG. 4 , the elastomeric layer  40  has grooves with a radius and flat portions etc. that result in the layer  40  being of variable thickness. For example, as shown in  FIG. 4  the elastomeric layer  40  has an outer surface  42  that is rounded, flat, wave-like etc. resulting in the layer  42  being generally non-linear. The variable thickness surface provides voids for the rubber to flow into when compressed by surface  24 . The voids may be shaped with a radius, flats, in a triangular or polygon shapes in order to provide additional retention force and resistance to removal. 
     In another aspect, the first elastomeric layer  38  adjoins the second elastomeric layer  40  (as generally designated at  44 , i.e. where the shoulder  32  meets the shank portion  34 ) to form a continuous elastomeric layer on the bushing  26 . 
     In another aspect, first elastomeric layer  38  can be formed on at least a portion of the shoulder  32 , i.e., could be formed on all of the shoulder  32  of the bushing  26  or could be formed on less than all of the shoulder  32  of the bushing  26 . In addition, second elastomeric layer  40  can be formed on at least a portion of the outer surface  36  of the shank portion  34 , i.e., could be formed on all of the outer surface  36  of the shank portion  34  or could be formed on less than all of the outer surface  36  of the shank portion  34  (as illustrated, for example, in  FIG. 6  where at least some of the outer surface  36  is not covered or coated with the elastomeric layer  40  which would result in the exposed portions of outer surface  36  contacting the inner wall  24  of receptacle  22  of the base  16 ). 
     It will be appreciated that the various aspects of the invention including, for example, the surfaces  36  in conjunction with the surfaces  38  and  40  has may advantages. For example, surface  36  could be a metal to metal press fit with surface  24 . But, by having the metal surfaces  36  surrounded by elastomeric surfaces  38  and  40  that are also interference fit with surface  24  it will isolate surfaces  36  from exterior conditions such as air, water, chemicals, etc. and act as a barrier to prevent rust on surfaces  36 . This in turn makes the bushing  26  easier to remove from the receptacle  22  of the base  16  after use. 
     Whereas particular aspects of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.