Patent Publication Number: US-2023151734-A1

Title: Washerless cutting tool assembly

Description:
FIELD OF THE DISCLOSURE 
     In general, the invention relates to a cutting tool assembly for the impingement of a substrate or earth strata, such as, for example, asphaltic roadway material, coal deposits, mineral formations, and the like. More specifically, the invention pertains to a cutting tool assembly with an alignment feature that eliminates the washer needed to properly align the rotatable cutting tool with the cutting tool holder. The invention also pertains to a cutting tool assembly with a limited rotation feature that selectively controls the amount of rotation of the rotating cutting tool during operation. 
     BACKGROUND OF THE DISCLOSURE 
     Rotatable cutting tools are useful for the impingement of a substrate or earth strata such as, for example, asphaltic roadway material, coal deposits, mineral formations and the like. Such a cutting tool typically presents a generally elongate, cylindrical geometry. The cutting tool comprises an elongate cutting tool body, which has an axially forward end and an opposite axially rearward end. A hard cutting member or a super hard cutting member typically affixes to the axial forward end of the cutting tool body. The cutting tool body typically carries an assembly or means by which the cutting tool is rotatably carried by a stationary block or holder on a drum. 
     Such rotatable cutting tools can experience extreme wear and failure in a number of ways due to the environment in which they operate and must be frequently replaced. Thus, it would be highly desirable to provide an improved cutting tool that experiences an increase in useful tool life with less parts and easier to manufacture, while reducing cost, as compared to conventional cutting tools. 
     SUMMARY OF THE DISCLOSURE 
     The problem of increasing the useful tool life of a rotatable cutting tool assembly, while reducing cost can be solved by eliminating the need for a washer that is required in conventional rotatable cutting tool assemblies for alignment of the cutting tool body with the cutting tool holder. 
     In one aspect, a washerless cutting tool assembly comprises a cutting tool holder having a central, longitudinal axis and a rotatable cutting tool at least partially disposed within the cutting tool holder. The rotatable cutting tool has a central, longitudinal axis and includes a cutting tool body having a head portion and a shank portion axially rearward of the head portion. The head portion and the shank portion are capable of being rotated about the central, longitudinal axis. The head portion includes a cutting member at an axial forward end thereof, a bolster portion axially rearward of the cutting member and a base portion at an axial rearward end of the head portion. The bolster portion includes a convex shape section having a socket at an axial forward end thereof. The cutting member is affixed to the cutting tool body within the socket. The cutting tool holder includes a protrusion at an axial forward end thereof, and the rotatable cutting tool includes a groove at an axial rearward end of the head portion, wherein the groove is capable of receiving the protrusion of the cutting tool holder to align the central, longitudinal axis of the rotatable cutting tool with the central, longitudinal axis of the cutting tool holder. 
     In another aspect, a rotatable cutting tool comprises a cutting tool body having a head portion and a shank portion axially rearward of the head portion. The head portion and the shank portion are capable of being rotated about a central, longitudinal axis. The head portion includes a cutting member at an axial forward end thereof, a bolster portion axially rearward of the cutting member and a base portion at an axial rearward end of the head portion. The bolster portion includes a convex shape section having a socket at an axial forward end thereof. The cutting member is affixed to the cutting tool body within the socket. The cutting tool holder includes a protrusion at an axial forward end thereof, and the rotatable cutting tool includes a groove at an axial rearward end of the head portion, wherein the groove is capable of receiving the protrusion of the cutting tool holder to align the central, longitudinal axis of the rotatable cutting tool with a central, longitudinal axis of the cutting tool holder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       While various embodiments of the invention are illustrated, the particular embodiments shown should not be construed to limit the claims. It is anticipated that various changes and modifications may be made without departing from the scope of this invention. 
         FIG.  1    is a side view of a washerless cutting tool assembly according to an embodiment of the invention; 
         FIG.  2    is a cross-sectional view of the washerless cutting tool assembly taken along line  2 - 2  of  FIG.  1   ; 
         FIG.  3    is a side view of a rotatable cutting tool of the washerless cutting tool assembly according to an embodiment of the invention; 
         FIG.  4    is a cross-sectional view of the rotatable cutting tool assembly taken along line  4 - 4  of  FIG.  3   ; and 
         FIG.  5    is an enlarged cross-sectional view of the alignment feature of the invention showing the cooperation between a protrusion on the axial forward end of the cutting tool holder and the groove on the axial rearward end of the rotatable cutting tool. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS.  1 - 5   , a washerless cutting tool assembly  10  is shown according to an embodiment of the invention. In one aspect, the cutting tool assembly  10  illustrated herein pertains generally to road planning tools. However, it should be appreciated that the invention has application to other kinds of cutting tools useful in other kinds of cutting operations. Exemplary operations include without limitation road planning (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, 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 assembly  10  of the invention may be manufactured in various sizes and dimensions depending upon the desired application of the tool. In another aspect, as used herein, the term “cutting tool” generally refers to rotatable cutting tools. 
     Directional phrases used herein, such as, for example, left, right, front, back, top, bottom and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein. Identical parts are provided with the same reference number in all drawings. 
     Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. 
     Throughout the text and the claims, use of the word “about” in relation to a range of values (e.g., “about 22 to 35 wt %”) is intended to modify both the high and low values recited, and reflects the penumbra of variation associated with measurement, significant figures, and interchangeability, all as understood by a person having ordinary skill in the art to which this invention pertains. 
     For purposes of this specification (other than in the operating examples), unless otherwise indicated, all numbers expressing quantities and ranges of ingredients, process conditions, etc., are to be understood as modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired results sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Further, as used in this specification and the appended claims, the singular forms “a”, “an” and “the” are intended to include plural referents, unless expressly and unequivocally limited to one referent. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements including that found in the measuring instrument. Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10, i.e., a range having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10. Because the disclosed numerical ranges are continuous, they include every value between the minimum and maximum values. Unless expressly indicated otherwise, the various numerical ranges specified in this application are approximations. 
     In the following specification and the claims, a number of terms are referenced that have the following meanings. 
     The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. 
     “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not. 
     As used herein, the term “elongate” is defined as something that is longer than it is wide. In other words, the width is smaller than its length. 
     As used herein, the term “circular” is defined as an object having a shape of a circle, i.e., an object having a simple closed shape. It is the set of points in a plane that are at a given distance from a given point, the center; equivalently it is the curve traced out by a point that moves in a plane so that its distance from a given point is constant. The distance between any of the points and the center is called the radius. 
     As shown in  FIGS.  1  and  2   , the washerless cutting tool assembly  10  comprises two main components: a cutting tool holder, shown generally at  12 , having a longitudinal axis, A-A, and a rotatable cutting tool, shown generally at  14 . In the illustrated embodiment, the cutting tool holder  12  is in the form of a sleeve member in which a portion of the rotatable cutting tool  14  is inserted within a bore  16  of the cutting tool holder  12 . In the illustrated embodiment, the rotatable cutting tool  14  is held in the cutting tool holder  12  with a friction fit created by compressing the retaining ring  80 . As is known in the art, the cutting tool  14  can be rotatably carried by the cutting tool holder  12  by inserting the cutting tool holder  12  into a bore of a drum (not shown). The cutting tool holder  12  has an axial forward end  18  and an axial rearward end  20 . 
     Referring now to  FIGS.  2 - 5   , the rotatable cutting tool  14  has a central, longitudinal axis B-B. In one aspect, the rotatable cutting tool  14  is rotatable about the axis B-B. In another aspect, rotatable cutting tool  14  may be symmetrical about the axis B-B. When the rotatable cutting tool  14  is properly mounted in the cutting tool holder  12 , the axis B-B of the rotatable cutting tool  14  is substantially aligned with the central, longitudinal axis A-A of the cutting tool holder  12 . 
     The rotatable cutting tool  14  includes an elongate cutting tool body, generally designated as  22 . In one aspect, the elongate cutting tool body  22  presents a generally cylindrical geometry and has an axial forward end  24  and an axial rearward end  26 . 
     The elongate cutting tool body  22  includes a head or head portion  28  and a shank or shank portion  30  axially rearward of the head portion  28 . In one aspect, the shank  30  includes an annular groove  32  adjacent the axial rearward end  26  ( FIGS.  2  and  4   ). It will be appreciated that the head  28  and the shank  30  may have various sizes, shapes and/or configurations in accordance with aspects of the invention. 
     In the illustrated embodiment, the head  28  includes a cutting member  34  at an axially forward end  35  of the head  28 , a bolster portion  36  axially rearward of the cutting member  34  and a base portion  38  at an axial rearward end  39  of the head  28 . 
     The bolster portion  36  includes a convex shape section  40  and a generally cylindrical section  42  contiguous with and axially rearward of the convex shape section  40 . In the illustrated embodiment, the convex shape section  40  is generally convex with an outer surface  44  being generally arcuate and curving outwardly from the central longitudinal axis B-B of the rotatable cutting tool  14 . In addition, the generally cylindrical section  42  is generally cylindrical in shape about the central, longitudinal axis B-B and includes an outer surface  43  that is generally linear and thus generally parallel to the central, longitudinal axis B-B. In one embodiment, the bolster portion  36  of the head  28  includes, at least in part, a cemented (cobalt) tungsten carbide material. 
     As shown in  FIG.  3   , the head  28  has an overall axial length dimension, H, the convex shape section  40  of the bolster portion  26  has an axial length dimension, X, and the generally cylindrical section  42  of the bolster portion  36  has an axial length dimension, Y. 
     In one embodiment, the axial length dimension, X, can be in the range of about 0.3 inches to about 1.0 inches. In another embodiment, the axial length dimension, X, can be in the range of about 0.6 inches to about 0.9 inches. In yet another embodiment, the axial length dimension, X, can be in the range of about 0.7 inches to about 0.8 inches. 
     In one embodiment, the axial length dimension, Y, can be in the range of about 0.03 inches to about 0.55 inches. In another embodiment, the axial length dimension, Y, can be in the range of about 0.1 inches to about 0.3 inches. 
     In one embodiment, the axial length dimension, H, can be in the range of about 1.7 inches to about 1.8 inches. In another embodiment, the axial length dimension, H, can be in the range of about 1.72 inches to about 1.78 inches. 
     In one embodiment, the ratio (X+Y)/H is in the range between about 0.25 to about 0.80. 
     In one embodiment, the axial length dimension, X, can be in the range of about 0.3 inches to about 1.0 inches, the axial length dimension, Y, can be in the range of about 0.03 inches to about 0.55 inches, the axial length dimension, H, can be in the range of about 1.7 inches to about 1.8 inches and the ratio (X+Y)/H can be in the range of about 0.5 to about 0.75. 
     Advantageously, a bolster portion  36  having the dimensions and/or ratios set forth herein along with being formed, at least in part, of a cemented (cobalt) tungsten carbide material allows for the bolster portion  36  to retain its shape and integrity for a longer period of time during use and aids in reducing wear to other components of the cutting tool assembly  10 , such as, for example, the shank  30  or cutting tool holder  12  for receiving the rotatable cutting tool  14 . 
     In another aspect of the invention, the convex shape section  40  of the bolster portion  36  can have a radius, R ( FIG.  3   ). In one embodiment, the radius, R, can be in the range of about 1.2 inches to about 1.4 inches. In another embodiment, the radius, R, can be in the range of about 0.85 inches to about 1.35 inches. Advantageously, this configuration of having the radius, R, provides the necessary structure and support for the cutting member  34 . In addition, this configuration advantageously provides, for example, the ability to add mass or size to the bolster portion  36  for improved wear while still maintaining a streamlined design for efficient cutting. 
     In another aspect, the ratio Y/X (i.e., the ratio of the axial length dimension of the generally cylindrical section  42  to the axial length dimension of the convex shape section  40 ) can be in the range of about 0.05 to about 1.0. In one embodiment, the ratio Y/X is in the range of about 0.1 to about 0.6. In another embodiment, the ratio Y/X is in the range of about 0.125 to about 0.300. Advantageously, this configuration regarding the ratio Y/X provides support and/or protection for the cutting member  34  during cutting and can reduce moment loading on the shank  30 , thereby reducing wear and extending the life of the cutting tool assembly  10 . 
     Referring particularly to  FIGS.  4  and  5   , the cutting member  34  includes a substrate  48  and a layer of a super hard material  50  adhered to the substrate  48 . The substrate  48  of the cutting member  34  is made of, at least in part, a cemented (cobalt) tungsten carbide material. The layer of super hard material  50  can be made of, for example, polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PcBN). The layer of super hard material  50  may have a generally constant thickness and can be applied to the substrate  48  by any one of a number of known techniques in which the super hard material  50  is bonded to the surface of the substrate  48 . In addition, the layer of super hard material  50  is shown as having a particular shape, but it will be appreciated that it may have other shapes, configurations and/or thicknesses as desired or required for particular cutting operations. 
     In the illustrated embodiment, the substrate  48  of the cutting member  34  includes sidewalls  56  that generally taper in the axial rearward direction. The substrate  48  also includes a bottom surface  58 . 
     Referring to  FIGS.  2 ,  4  and  5   , the bolster portion  36  includes a socket  52  at an axial forward end  54  that is configured for receiving and affixing the cutting member  34  to the cutting tool body  14 . Generally, the socket  52  includes a sidewall  60  configured for cooperating with and receiving the substrate  48  of the cutting member  34 . More particularly, the socket  52  includes sidewalls  60  structured and arranged for receiving the tapered sidewalls  56  of the substrate  48  of the cutting member  34 . In one embodiment, the sidewalls  60  of the socket  52  generally taper in the axial rearward direction, similar to the tapering of the sidewalls  56  of the substrate  48 . In the illustrated embodiment, the socket  52  includes a bottom surface  62  that, in one example, may be spaced apart from the bottom surface  58  of the substrate  48 . 
     In the illustrated embodiment, the cutting member  34  can be affixed to the bolster portion  36  by brazing the sidewalls  56  of the substrate  48  to the sidewalls  60  of the socket  52 . Although not required, brazing may also be provided between the bottom surface  58  of the substrate  48  and a bottom surface  62  of the socket  52 . In order to enhance the brazing between the sidewalls  56  of the substrate  48  and the sidewalls  60  of the socket  52 , a plurality of projections (not shown) may be provided and formed on the sidewall  60  of the socket  52 . Generally, the plurality of projections (not shown) are configured for cooperating with the substrate  48  of the cutting member  34  for affixing the cutting member  34  to the cutting tool body  14 . More particularly, the projections (not shown) provide a raised surface that extends outwardly from the sidewall  60  such that the sidewall  56  of the substrate  48  contacts and rests thereon providing spacing or a gap between sidewalls  56  and  60  so as to allow the braze to flow more easily and uniformly between the sidewalls  56  and  60 . In addition, the projections (not shown) can provide for accurate positioning, for example, centering, of the substrate  48  in the socket  52 . It will be appreciated that other configurations and arrangements of the projections (not shown) can be provided in accordance with aspects of the invention. In addition, it will be appreciated that the substrate  48 , the cutting member  34  and/or the socket  52  may have various shapes, sizes and configurations in accordance with aspects of the invention. 
     As shown in  FIGS.  2 ,  4  and  5   , the base portion  38  defines a pocket  66  configured for cooperating with and receiving the axial rearward end  46  of the bolster portion  36  for affixing or securing the bolster portion  36  to the base portion  38 . In one example, the pocket  66  can include a first segment  68 , a second segment  70  axially rearward of the first segment  68  and a bottom  72  disposed rearward of the first and second segments  68 ,  70 . It will be appreciated that other configurations and arrangements for the pocket  66  can be provided in accordance with aspects of the invention. 
     Referring again to  FIGS.  2 ,  4  and  5   , in one example a rearward end  46  of the bolster portion  36  includes a first portion  74 , a second portion  76  axially rearward of the first portion  74 , and a bottom portion  78  rearward of the first and second portions  74 ,  76 . It will be appreciated that other configurations and arrangements for the rearward end  46  can be provided in accordance with aspects of the invention. In addition, it will be appreciated that the pocket  66  is configured and arranged for receiving and affixing the rearward end  46  thereto. 
     More particularly, in one embodiment, the rearward end  46  of the bolster portion  36  can be affixed or attached by brazing the first portion  74 , the second portion  76  and/or the bottom portion  78  to the first segment  68 , second segment  70  and/or the bottom  72 , respectively, of the pocket  66 . In order to enhance the described brazing a plurality of projections (not shown) may be provided and formed on the first portion  74  of the rearward end  46 . In addition, to further enhance the brazing, a plurality of ribs (not shown) can be provided and formed on the second portion  76  of the rearward end  46 . 
     Referring now to  FIGS.  2 - 4   , the rotatable cutting tool  14  includes a limited rotation feature. In the illustrated embodiment, the limited rotation feature comprises a braking ring  79  disposed within the annular groove  32  in the shank  30 , and a wedding-style retainer ring  80  disposed over the braking ring  79 . The braking ring  79  of made of a suitable material that acts as a brake to slow, limit and/or stop the rotation of the rotatable cutting tool  14  during operation. The braking ring  79  can be made of any suitable material, such as urethane, and the like. By slowing, limiting and/or stopping the rotation of the rotatable cutting tool  14  by a certain percentage, for example, 25-50%, it is estimated that the tool life is increased by approximately the same percentage. If the braking ring  79  and the retainer ring  80  are sufficiently tightened, the rotation of the rotatable cutting tool  14  could be completely stopped and the rotatable cutting tool  14  can then be considered an indexable cutting tool that can be rotated by the user on a daily, weekly or monthly basis, depending on the needs of the application. In addition, the rotatable cutting tool  14  can be easily removed when the user needs to switch back to a cutting tool having a cutting member  34  made of a different material, such as carbide, and the like. 
     As mentioned above, the central, longitudinal axis B-B of the rotatable cutting tool  14  is substantially aligned with the central, longitudinal axis A-A of the cutting tool holder  12  when the rotatable cutting tool  14  is properly mounted in the cutting tool holder  12 . In conventional cutting tool assemblies, this is accomplished by the use of a washer disposed between the rotatable cutting tool and the cutting tool holder. 
     One aspect of the invention is that the washer used in conventional cutting tool assemblies for aligning the rotatable cutting tool  14  with the cutting tool holder  12  is eliminated in the cutting tool assembly  10  of the invention, thereby reducing the cost of manufacture, while extending the life of the cutting tool assembly  10 . 
     Referring to  FIG.  5   , the elimination of a washer in conventional cutting tools is achieved by providing a chamfered surface  82 , a radial support surface  84 , and a protrusion  86  at the axial forward end  18  of the cutting tool holder  12 . In one embodiment, the chamfered surface  82  extends at an angle, A, in a range between about 30 and 60 degrees with respect to the central, longitudinal axis, B-B. As shown in  FIG.  5   , the protrusion  86  extends axially forward with respect to the radially extending support surface  84  by a distance, D. In other words, the protrusion  86  extends upward from the radial support surface  84  towards the axial forward end  24  of the rotatable cutting tool  14 . In one embodiment, the distance, D, is in the range of about 0.5 mm to about 10 mm. In one embodiment, the radial support surface  84  extends substantially perpendicular with respect to the central, longitudinal axis A-A of the cutting tool holder  12 . However, it will be appreciated that the radially extending support surface  84  can extend at an acute or obtuse angle with respect to the central longitudinal axis, A-A. It will be appreciated that other configurations and arrangements for the axial forward end  18  can be provided in accordance with aspects of the invention. 
     Similarly, the axial rearward end  39  of the head  28  of the rotatable cutting tool  14  is provided with a chamfered surface  88 , a radial support surface  90 , and a groove  92  disposed between the chamfered surface  88  and the radial support surface  90  that cooperate with the chamfered surface  82 , the radial support surface  84  and the protrusion  86 , respectively, of the cutting tool holder  12 . In particular, the chamfered surface  88  of the rotatable cutting tool  14  extends at substantially the same angle, A, with respect to the central, longitudinal axis, B-B, as the chamfered surface  82  of the cutting tool holder  12 . In addition, the groove  92  has at least a depth, D, to allow the protrusion  86  to be completely disposed therein. In one embodiment, the groove  92  comprises an annular groove. Further, the radial support surface  90  of the rotatable cutting tool  14  is substantially perpendicular to the central, longitudinal axis, B-B. 
     The cooperation between the protrusion  86  of the cutting tool holder  12  and the annular groove  92  of the rotatable cutting tool  14  provides an alignment feature that enables the rotatable cutting tool  14  to be properly aligned with the cutting tool holder  12 , thereby eliminating the need for a washer required in conventional cutting tool assemblies. 
     The patents and publications referred to herein are hereby incorporated by reference. 
     Having described presently preferred embodiments the invention may be otherwise embodied within the scope of the appended claims.