Patent Publication Number: US-8523289-B2

Title: Retention assembly for cutting bit

Description:
CROSS-REFERENCE TO EARLIER PATENT APPLICATION 
     This patent application is a non-provisional patent application is based in part upon U.S. Provisional Patent Application Ser. No. 61/168,270 filed on Apr. 10, 2009 by Eric P. Helsel and Stephen P. Stiffler for a RETENTION ASSEMBLY FOR CUTTING BIT. Under the United States Patent Statute, applicants herein (Eric P. Helsel, Don Rowlett, Donald E. Keller and Stephen P. Stiffler) hereby claim the priority of said provisional patent application (U.S. Provisional Patent Application Ser. No. 61/168,270 filed on Apr. 10, 2009 by Helsel and Stiffler for a RETENTION ASSEMBLY FOR CUTTING BIT). Further, applicants hereby incorporate by reference herein the entirety of the above mentioned U.S. Provisional Patent Application Ser. No. 61/168,270 filed on Apr. 10, 2009 to Helsel and Stiffler. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to a retention assembly for a cutting bit. More particularly, the invention pertains to a retention assembly for retaining a cutting bit holder (or tool holder) in a support block (or base) during use wherein the cutting bit holder carries the cutting bit. 
     Mining machines and construction machines (e.g., a road planing machine or road milling machine) are useful in continuous mining or road milling applications to mine or mill earth strata such as, for example, coal, asphalt, concrete and the like. These mining machines and construction machines utilize cutting bit assemblies. Each cutting bit assemblies for continuous mining or road milling applications typically comprises a cutting bit rotatably mounted within a support block. In turn, the support block mounts, typically by welding, on a drum or other body, wherein a suitable power source (or means) drives the drum. When a number of such support blocks carrying cutting bits are mounted onto a drum, and the drum is driven, the cutting bits will impinge and break up the earth strata into many pieces (i.e., cutting debris). Skilled artisans know the general operation of such a mining machine or construction machine. U.S. Pat. No. 7,144,192 to Holl et al. for a SELF-PROPELLED ROAD MILLING MACHINE, U.S. Pat. No. 7,370,916 to Ley et al. for a REAR LOADER ROAD MILLING MACHINE WITH HEIGHT-ADJUSTABLE SEALING DEVICE, and U.S. Pat. No. 7,070,244 to Fischer et al. for a ROAD MILLING MACHINE are exemplary patent documents that disclose such mining machines and/or construction machines. 
     During operation of the mining or construction machine, the support block experiences wear due to exposure thereof to the cutting debris. Over time, wear and other kinds of abuse causes the support block to become ineffective which signals an end to its useful life. Once this occurs, the operator must cut or torch the support block off the drum to allow for replacement of the support block. Typically, the operator welds the replacement support block on the drum. As the skilled artisan appreciates, it is time-consuming, and hence costly, to remove and replace a support block. Thus, there is an advantage to be able to prolong the useful life of the support block. 
     To prolong the life of the support block, one may use a cutting bit holder, sometimes referred to as a cutting bit sleeve, wherein the cutting bit rotatably or otherwise releasably mounts within the cutting bit holder. The cutting bit holder mounts within the support block via a mechanical connection. The presence of the cutting bit holder helps protect the support block from abuse and wear, thus minimizing or eliminating the periods of down time otherwise required for drum repair. The skilled artisan is aware of the use of cutting bit holders. 
     The skilled artisan is aware that cutting bits and cutting bit holders are subjected to considerable stresses during mining operations, road milling operations or other like operations. Accordingly, there is a desire to mount the cutting bit holder in the support block to minimize movement of the cutting bit holder in order to maximize the useful life of the cutting bit. It is also important that the mounting between the cutting bit holder and the support block be resistant to vibratory loosening which could likewise lead to premature cutting bit wear and failure. Heretofore, various structures exist to mount a cutting bit sleeve within a support block in an attempt to minimize cutting bit holder movement or loosening, while maximizing cutting bit life. 
     A mining machine or a road milling machine operates typically in severe operating conditions. During operation, the cutting bit holder (or tool holder) and/or the support block (or base) can experience damage such that it is difficult to disassemble these components. It is an advantage to be able to disassemble the cutting bit holder from the support block. Thus, it would be highly desirable to provide a cutting bit holder-support block assembly that facilitates a relatively easy disassembly of the cutting bit holder from the support block. Further, during operation, the severe operating conditions can also cause the rotatable cutting bit to lodge in the bore of the cutting bit holder. It would be advantageous to disassemble the cutting bit from the cutting bit holder. Thus, it is highly desirable to provide a cutting bit-cutting bit holder assembly that facilitates the relatively easy disassembly of the cutting bit from the cutting bit holder. 
     The following patent documents are exemplary of these various structures: U.S. Pat. No. 5,067,775 to D&#39;Angelo for RETAINER FOR ROTATABLE BITS; U.S. Pat. No. 6,129,422 to Siddle et al. for a CUTTING TOOL HOLDER RETENTION SYSTEM; U.S. Pat. No. 5,769,505 to Siddle et al. for a CUTTING TOOL HOLDER RETENTION SYSTEM; U.S. Pat. No. 6,220,671 to Montgomery, Jr. for a CUTTING TOOL HOLDER RETENTION SYSTEM; U.S. Pat. No. 6,234,579 to Montgomery, Jr. for a CUTTING TOOL HOLDER RETENTION SYSTEM; U.S. Pat. No. 6,331,035 to Montgomery, Jr. for a CUTTING TOOL HOLDER ASSEMBLY WITH PRESS FIT; U.S. Pat. No. 3,749,449 to Krekeler for a MEANS FOR REMOVABLY AFFIXING CUTTER BIT AND LUG ASSEMBLIES TO DRIVER ELEMENT OF A MINING MACHINE OR THE LIKE; U.S. Pat. No. 4,650,254 to Wechner for a BIT HOLDER; and U.S. Pat. No. 5,607,206 to Siddle et al. for a CUTTING TOOL HOLDER RETENTION SYSTEM. 
     SUMMARY OF THE INVENTION 
     In one form thereof, the invention is a cutting bit retention assembly that comprises a cutting bit holder, which has a leading end and a trailing end. The bit holder has a head section adjacent to the leading end and a shank section adjacent to the trailing end. The head section of the cutting bit holder contains a cutting bit bore adapted to receive the cutting bit. The shank section of the cutting bit holder contains a slot defined by a slot surface. There is a support block, which contains a cutting bit holder bore. The support block further contains a transverse bore wherein the transverse bore opens into the cutting bit holder bore. The cutting bit holder bore is adapted to receive the shank section of the cutting bit holder. There is a retention pin, which is received within the transverse bore whereby the retention pin extends into the slot. The retention pin selectively is in a non-retaining position wherein the retention pin does not engage the slot surface or a retaining position in which the retention pin engages the slot surface to urge the cutting bit holder into the cutting bit holder bore or an ejecting position in which the retention pin engages the slot surface to urge the cutting bit holder out of the cutting bit holder bore. 
     In another form thereof, the invention is a cutting bit holder for use with a support block. The cutting bit holder comprises a cutting bit holder body that has a leading end and a trailing end. The cutting bit holder body has a head section adjacent to the leading end and a shank section adjacent to the trailing end. The shank section has a central longitudinal axis. The head section of the cutting bit holder contains a cutting bit bore adapted to receive the cutting bit. The cutting bit bore has a central longitudinal axis. The shank section of the cutting bit holder contains a slot defined by a slot surface. The slot surface includes a pair of spaced-apart generally planar side slot surfaces wherein the side slot surfaces being generally parallel to each other. The slot surface has an arcuate side slot surface joining together the generally planar side slot surfaces. 
     In yet another form thereof, the invention is a support block for use with a cutting bit holder. The support block comprises a support block body containing a cutting bit holder bore adapted to receive the shank section of the cutting bit holder that contains a slot defined by a slot surface. The support block further contains a transverse bore, and the transverse bore opens into the cutting bit holder bore. There is a retention pin threadedly received within the transverse bore and passing into the cutting bit holder bore. The retention pin selectively is in a non-retaining position and a retaining position and an ejecting position. When the retention pin is in the non-retaining position, the retention pin does not engage the slot surface. When the retention pin is in the retaining position, the retention pin engages the slot surface to urge the cutting bit holder into the cutting bit holder bore in the support block. When the retention pin is in the ejecting position, the retention pin engages the slot surface to urge the cutting bit holder out of the cutting bit holder bore in the support block. 
     In another form thereof, the invention is a camming pin for use in engaging or disengaging a cutting bit holder to a support block containing a slot defined by a slot surface. The camming pin comprises an elongate pin body having an attachment section wherein the camming pin attaches to the support block at the attachment section. The elongate pin body further has a camming section wherein the camming section engages the slot surface to either move the cutting bit holder into engagement with the support block or to move the cutting bit holder out of engagement with the support block. 
     In another form thereof, the invention is a cutting tool holder-base assembly that comprises a cutting tool holder, which has a head region containing a cutting tool bore. The cutting tool holder further contains a shank region that has a distal end and a notch defined by a notch surface at the distal end, The assembly further includes a base containing a tool holder bore and a transverse passage intersecting the tool holder bore. The assembly further comprises a camming pin received within the transverse passage, The camming pin presents a camming region in the tool holder bore. The camming region is movable to any one of a neutral position to facilitate complete insertion of the shank region into the bore of the base, a retention position wherein the camming region engages the notch surface to facilitate the engagement of the tool holder to the base, and a disengagement position wherein the camming region engages the notch surface to facilitate the disengagement of the tool holder from the base. 
     In yet another form thereof, the invention is a cutting tool holder for receipt in a bore of a base member having a threaded camming pin with a camming region in the bore. The cutting tool holder comprises a head region, which contains a cutting tool bore, and contains a shank region, which has a distal end. The shank region has a notch defined by a notch surface at the distal end thereof. The cutting tool holder further contains a positioning bore adapted to receive a positioning tool. 
     In still another form thereof, the invention is a base for use with a cutting tool holder wherein the base comprises a base body that contains a tool holder bore and a transverse passage intersecting the tool holder bore. There is a camming pin received within the transverse passage wherein the camming pin presents a camming region in the tool holder bore. The camming region is movable to any one of a neutral position to facilitate complete insertion of the shank region into the bore of the base, a retention position wherein the camming region engages the notch surface to facilitate the engagement of the tool holder to the base, and a disengagement position wherein the camming region engages the notch surface to facilitate the disengagement of the tool holder from the base. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following is a brief description of the drawings: 
         FIG. 1  a side view of a road milling machine in operation showing a milled surface of the roadway and an unmilled surface of the roadway along with debris exiting the conveyor of the road milling machine; 
         FIG. 2  is a side view of a first specific embodiment of the inventive cutting bit assembly including the support block, the cutting bit holder and the cutting bit wherein these components are exploded away from each other, as well as the threaded cam pin exploded away from the support block; 
         FIG. 3  is a side view of the cutting bit assembly of  FIG. 2  in an assembled condition; 
         FIG. 4  is an isometric view of the threaded cam pin, which when in use is threadedly received in a threaded bore in the support block; 
         FIG. 5  is an end view of the threaded cam pin of  FIG. 4  showing the end of the camming section; 
         FIG. 6  is a side view of the cutting bit holder of the specific embodiment of  FIG. 2  with a section of the shank section of the cutting bit holder cut away; 
         FIG. 6A  is an isometric view of the rearward end of the cutting bit holder illustrating the central longitudinal bore and the elongate slot in the shank section; 
         FIG. 7  is a end view of the cutting bit holder of  FIG. 6  illustrating only the shank section of the cutting bit holder; 
         FIG. 8  is a side view of the cutting bit of the specific embodiment of the cutting bit assembly of  FIG. 2 ; 
         FIG. 9  is a cross-sectional view of the assembled cutting bit assembly taken along section line Z-Z of  FIG. 3  showing the threaded cam pin in engagement with the slot wall after counter-clockwise rotation to urge the cutting bit holder away from the support block; 
         FIG. 10  is a cross-sectional view of the assembled cutting bit assembly taken along section line Z-Z of  FIG. 3  showing the threaded cam pin in a neutral position in which the threaded cam pin does not engage the slot wall so that the shank section is free to be inserted into the cutting bit holder bore of the support block; 
         FIG. 11  is a cross-sectional view of the assembled cutting bit assembly taken along section line Z-Z of  FIG. 3  showing the threaded cam pin in engagement with the slot wall after clockwise rotation to urge the cutting bit holder into the support block; 
         FIG. 12  is an isometric view of the tool holder-base assembly of another specific embodiment of the invention; 
         FIG. 13  is a cross-sectional schematic view of the base with the threaded cam pin in a neutral position; 
         FIG. 13A  is a cross-sectional schematic view of the base with the threaded cam pin in a neutral position and the shank region of the tool holder in the tool holder bore of the base whereby the camming section is proximate to the flat surface of the shank region of the tool holder; 
         FIG. 13B  is an enlarged cross-sectional view of the area of the camming pin and the flat surface of the tool holder from  FIG. 13A  and shown by the dashed circle marked  13 B in  FIG. 13A ; 
         FIG. 13C  is a cross-sectional schematic view of the base with the threaded cam pin in a position of initial retention contact with the flat surface of the shank wherein the position of initial retention contact is the result of the clockwise rotation of the threaded cam pin from the neutral position (see  FIG. 13A ) to the point of initial retention contact; 
         FIG. 13D  is a cross-sectional schematic view of the base with the threaded cam pin in a position of maximum retention contact with the flat surface of the shank region wherein the position of maximum retention contact is the result of the clockwise rotation of the threaded cam pin from the position of initial contact (see  FIG. 13C ) to this position of maximum retention contact; 
         FIG. 13E  is a cross-sectional schematic view of the base with the threaded cam pin in a position of initial disengagement contact with the flat surface of the shank region wherein the position of initial disengagement contact is the result of the counterclockwise rotation of the threaded cam pin from the neutral position (see  FIG. 13A ); 
         FIG. 13F  is a cross-sectional schematic view of the base with the threaded cam pin in a position of maximum disengagement contact with the flat surface of the shank region wherein the position of maximum disengagement contact is the result of the counterclockwise rotation of the threaded cam pin from the position of initial disengagement contact (see  FIG. 13E ) to this position of maximum disengagement contact; 
         FIG. 14  is a cross-sectional schematic view of the base with the threaded cam pin in the neutral position and the shank region of the tool holder partially within the tool holder bore of the base due to an abutment against the threaded cam pin because of misalignment between the tool holder and the base; 
         FIG. 15A  is an isometric view of the threaded cam pin; 
         FIG. 15B  is a cross-sectional view of the threaded cam pin of  FIG. 15A  taken along section line  15 B- 15 B; 
         FIG. 16  is an isometric view of the base with the threaded cam pin in the transverse passage; 
         FIG. 17  is an isometric view of the tool holder of the tool holder-base assembly illustrated in  FIG. 12 ; 
         FIG. 18  is a cross-sectional schematic view of the tool holder exploded away from the base; 
         FIG. 19  is a side view of the installation-removal tool for use with the tool holder of  FIG. 17 ; 
         FIG. 20  is a front view of a specific embodiment of a tool holder-base assembly wherein the tool holder is sleeve; and 
         FIG. 21  is a cross-sectional view of the tool holder-base assembly of  FIG. 20  taken along section line  21 - 21  of  FIG. 20 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings,  FIG. 1  shows a road milling machine generally designated as  30 . Road milling machine  30  travels over a roadway generally designated as  32  wherein the roadway  32  exhibits an unmilled roadway  34  and a milling roadway  36 .  FIG. 1  illustrates the milled roadway  36  as having a top layer removed to be lower than the unmilled roadway  34 . 
     As the skilled artisan appreciates, the road milling machine  30  contains a rotatable road milling drum  44 . Road milling drum  44  presents a cylindrical surface  46 . A plurality of support blocks (described hereinafter) mount such as, for example, by welding of the cylindrical surface  46 . As will be described hereinafter for a specific embodiment of the inventive cutting bit assembly, each support block retains a cutting bit holder, and the cutting bit holder retains a cutting bit. The inventive cutting bit retention assembly comprises the support block and the cutting bit holder. When a number of such cutting bit retention assemblies carrying cutting bits (i.e., cutting bit assemblies) mount to a drum, and the drum is driven, the cutting bits impinge and break up the earth strata (e.g., asphaltic roadway material, concrete, coal, and the like) into many pieces (i.e., cutting debris). The road milling machine  30  includes a conveyor  38  from which asphaltic debris (or milling debris) exits during operation. U.S. Pat. No. 7,144,192 to Holl et al. for a SELF-PROPELLED ROAD MILLING MACHINE, U.S. Pat. No. 7,370,916 to Ley et al. for a REAR LOADER ROAD MILLING MACHINE WITH HEIGHT-ADJUSTABLE SEALING DEVICE, and U.S. Pat. No. 7,070,244 to Fischer et al. for a ROAD MILLING MACHINE disclose exemplary road milling machines. 
     During operation of the road milling machine, the support block experiences wear due to exposure thereof to the cutting debris. Over time, wear and other kinds of abuse causes the support block to be ineffective which signals an end to its useful life. Once this occurs, the operator must cut or torch the support block off the drum to allow for replacement of the support block. Typically, the operator welds the replacement support block to the drum. As the skilled artisan appreciates, it is time-consuming and hence costly, to remove and replace a support block. Thus, there is an advantage to be able to prolong the useful life of the support block. The present invention provides for that advantage. 
     The cutting bits and cutting bit holders are subjected to considerable stresses during road milling operations. Accordingly, there is a desire to mount the cutting bit holder in the support block to minimize movement of the cutting bit holder in order to maximize the useful life of the cutting bit. It is also important that the mounting between the cutting bit holder and the support block be resistant to vibratory loosening which could likewise lead to premature cutting bit wear and failure. The present invention provides a secure mounting of the cutting bit to the cutting bit holder and of the cutting bit holder to the support block. 
     A mining machine or a road milling machine operates typically in severe operating conditions. During operation, the cutting bit holder (or tool holder) and/or the support block (or base) can experience damage such that it is difficult to disassemble these components. It is an advantage to be able to disassemble the cutting bit holder from the support block. Thus, it would be highly desirable to provide a cutting bit holder-support block assembly that facilitates a relatively easy disassembly of the cutting bit holder from the support block. Further, during operation, the severe operating conditions can also cause the rotatable cutting bit to lodge in the bore of the cutting bit holder. It would be advantageous to disassemble the cutting bit from the cutting bit holder. Thus, it is highly desirable to provide a cutting bit-cutting bit holder assembly that facilitates the relatively easy disassembly of the cutting bit from the cutting bit holder. 
     Referring to the drawings and especially  FIG. 2  and  FIG. 3 , the cutting bit assembly comprises the combination of the support block  50 , the cutting bit holder  54  and the cutting bit  58 .  FIG. 2  illustrates these three components in an exploded fashion. The cutting bit retention assembly comprises the components of the support block  50  and the cutting bit holder  54 . A description of each component now follows. 
     Support block  50  has a block body  60  which has a top end  62  and a bottom end  64 . The bottom end  64  is generally arcuate to conform with the curvature of the cylindrical surface  46  of the drum  44 . The block body  60  includes a base  66  and an integral protrusion  68 , which has a forward face (or surface)  70 . The protrusion  70  of the block body  60  contains a cutting bit holder bore  72 , which has an axial forward end  74  and an axial rearward end  76 . The cutting bit holder bore  72  has a central longitudinal axis A-A. 
     The cutting bit holder bore  72 , which is an open bore, has an axial forward end and an axial rearward end. There is access to the rearward end of the tool holder through the axial rearward end of the cutting bit holder bore  72 . Through this access, the operator can cause an impact on the rearward end of the tool holder to facilitate to disassembly of the tool holder from the base. As mentioned above, during operation, the tool holder and/or the base may suffer damaged or at least impacted so that disassembly is difficult. The above access facilitates the disassembly of the cutting bit holder from the support block. This is an advantage provided by the present invention. 
     The cutting bit holder bore  72  has a major frusto-conical bore section  78  wherein the transverse dimension thereof decreases in the axial rearward direction. The major frusto-conical bore section  78  is at the axial forward end  74  of the cutting bit holder bore  72 . The cutting bit holder bore  72  has a minor frusto-conical bore section  80  wherein the transverse dimension thereof increases in the axial rearward direction. In reference to the major frusto-conical bore section  78  and the minor frusto-conical bore section  80 , the transverse dimension is the dimension perpendicular to the central longitudinal axis A-A of the cutting bit holder  72 . Finally, the cutting bit holder  72  has a cylindrical bore section  82  at the axial rearward end  76  thereof. The minor frusto-conical bore section  80  is mediate of and contiguous with the major frusto-conical bore section  78  and the cylindrical bore section  82 . The cutting bit holder bore  72  is adapted to receive the shank section  110  of the cutting bit holder  54 . 
     The support block  50  further contains a threaded bore (or transverse bore)  86 , which has a central longitudinal axis B-B. Threaded bore  86  has an exterior end  88  at the surface of the block body  60  and an interior end  90  adjacent the cutting bit holder bore  72 . The threaded bore  86  opens into the cutting bit holder bore  72  of the support block  50 . The central longitudinal axis B-B of the threaded bore  86  is generally transverse at an angle of 90° (or perpendicular) to the central longitudinal axis A-A of the cutting bit holder bore  72 . As will become apparent from the description hereinafter, the threaded bore  86  threadedly receives a threaded cam pin  170 . 
     The support block  50  also contains a pair of closed bores  92  which open at the bottom surface  64 . These closed bores  92  are adapted to receive upstanding posts  48  that protrude from the surface  46  of the drum  44 . These posts  48  facilitate the attachment and positioned of the support blocks  50  on the surface  46  of the drum  44 . In this regard, support blocks  50  are typically distributed over and mounted to, such as by welding, the circumference and length of the drum  44  according to any desired pattern. A conventional and suitable power source drives the drum to cause the cutting bits  58  to impinge and break up the earth strata thereby generating cutting debris. 
     The cutting bit holder  54  includes a holder body generally designated as  100  that has a forward (or leading) end  102  and a rearward (or trailing) end  104 . Cutting bit holder  54  has a head section  106  adjacent to the leading end  102 , and a mediate section  108  contiguous with and axial rearward of the head section  106 . The cutting bit holder  54  further includes a shank section  110  contiguous with and axial rearward of the mediate section  108 . Shank section  110  has a central longitudinal axis E-E. The shank section  110  presents a generally frusto-conical shape. In this regard, the shank section  110  has a transverse dimension “N”, which is generally perpendicular to axis E-E, that decreases in the axial rearward direction. The shank section  110  decreases in its transverse dimension at an angle “D”. In other words, the shank section  110  has an angle of taper “D”. This taper is a self-locking and self-releasing taper. The angle of taper D ranges between about 5 degrees and about 15 degrees. The preferred angle of taper D is equal to about 11 degrees. Although the shank section  110  presents a frusto-conical shape, there is the contemplation that the shank section may present a geometry other than frusto-conical such as, for example, cylindrical. The head section  106  has a forward face  112  at the leading end  102 . The mediate section  108  has an enlarged diameter (or transverse dimension) collar  113  and a collar face  114  that faces in the axial rearward direction. 
     The head section  108  contains a cylindrical cutting bit bore  118  that has a forward end  120  and a rearward end  122 . Cylindrical bore  118  has a central longitudinal axis C-C. Cylindrical bore  118  is adapted to receive the cutting bit  58  as will be described hereinafter. The central longitudinal axis C-C of the cylindrical bore  118  is not in axial alignment with the central longitudinal axis A-A of the cutter bit holder bore  72 . 
     Referring to  FIGS. 2 ,  6 ,  6 A and  7 , the shank section  110  contains an elongate slot  130 . The elongate slot  130  has an open end  134 , which opens at the trailing end  104  of the holder  54 . The slot  130  has a closed end  136  that forms the axial forward termination of the elongate slot  130 , which is axial rearward of the collar face  114  of collar  113 . The shank section  110  further contains a central longitudinal closed bore  140 . Closed bore  140  has a closed end  142  and an open and  144 . 
     The overall slot surface  132  defines the elongate slot  130 . The overall slot surface  132  comprises a pair of spaced-apart generally planar side surfaces  146 ,  147  and an arcuate surface  148 . The arcuate surface  148  joins the side surfaces  146  and  147 . As shown in  FIGS. 6A and 7 , the side surfaces  146  and  147  are generally parallel with respect to each other. 
     The cutting bit  58  typically has an elongated body that has an axial forward end  150  and an axial rearward end  152 . The cutter bit  58  has a central longitudinal axis G-G. The cutting end of the cutting bit  58  typically comprises a hard cutting insert  154 , which can be cemented carbide, mounted by brazing or the like at the axial forward end of the cutting bit body. The cutting bit  58  further includes a cutting bit shank section  159  adjoining a rearwardly facing surface  158 . A skilled artisan is familiar with cutting bits so that the cutting bit  58  needs no further description herein. An exemplary patent document that discloses a cutting bit is U.S. Pat. No. 4,497,520 to Ojanen. 
     The cutting bit bore  118 , which is a open bore, has an axial forward end  120  and an axial rearward end  122 . There is access to the rearward end  152  of the cutting bit  58  through the axial rearward end  122  of the cutting bit bore  118 . Through this access, the operator can cause an impact on the rearward end of the cutting bit to facilitate disassembly of the cutting bit from the cutting bit holder. As mentioned above, during operation, the cutting bit and/or the cutting bit holder may suffer damage or at least impact such that disassembly is difficult. The above access facilitates the disassembly of the cutting bit from the cutting bit holder. This is an advantage provided by the present invention. 
     Referring to  FIG. 4  and  FIG. 5 , the cutting bit retention assembly further includes a threaded cam pin (or retention pin) generally designated as  170 . The threaded cam pin  170  has an external end  172  and an opposite internal end  174 . The threaded cam pin  170  has a threaded section (bracket  176 ) and a smooth camming section (bracket  178 ). The camming section  178  is generally cylindrical in geometry, except that an arcuate notch  182  is in the camming section  178 . The arcuate notch  182  travels the axial length of the camming section  178 . A pair of opposite edges  184 ,  186  define the periphery of the arcuate notch  182 . As shown in  FIGS. 4 and 5 , a straight line or chord X-X passes through the opposite edges  184 ,  186 . 
     As is apparent from a consideration of  FIG. 2  and  FIG. 11 , the threaded cam pin  170  threads into the threaded bore whereby the camming section  178  extends into the cutting bit holder bore  72 . While the extent to which the threaded cam pin  170  threads into the threaded bore can vary, the threaded cam pin  170  functions as an alignment guide for the insertion of the cutting bit holder  54  when it extends into the cutting bit holder bore  72 . 
     In regard to the assembly of the cutting bit holder  54  to the support block  50 , one inserts the shank portion  110  of the cutting bit holder  54  into the cutting bit holder bore  72  (of the support block  50 ) as the first step to connecting the cutting bit holder  72  to the support block  50 . One can achieve correct relative alignment between the cutting bit holder  54  and the block  50  when the threaded cam pin  170  aligns with the elongate slot  130 . The cutting bit holder  54  is fully within the cutting bit holder bore  72  when the collar face  114  (of the collar  113 ) contacts against the forward face  70  of the block body  60  such as shown in  FIG. 2 . 
     In order for the slot  130  to accommodate the threaded cam pin  170 , the threaded cam pin  170  must present the orientation, which is a neutral position, as shown in  FIG. 10 . More specifically, the threaded cam pin  170  is threaded into the threaded bore  86  in the support block  50  to a depth so that the threaded cam pin  170  satisfies two conditions. One such condition is that the camming section  178  extends into the cutting bit holder base  72 . When in this condition, the threaded camming pin  170  provides an alignment feature to correctly align the cutting bit holder with the support block. 
     The other condition is that the camming section  178  has an orientation as illustrated in  FIG. 10 . When in the condition shown by  FIG. 10 , the chord (i.e., the straight line X-X) between the opposite edges  184 ,  186  is generally parallel to the side slot walls  146 ,  147  that define the slot  130 . When in this condition, the minimum transverse dimension “U” (see  FIG. 10 ) of the camming section  178  is aligned with the slot  130 , which has a width of “V” (see  FIG. 10 ). Width V of the slot  130  is greater than the minimum transverse dimension U so that the slot  130  accommodates travel of the camming section  178  therethrough whereby the cutting bit holder  54  slides past the camming section  178  into the cutting bit holder bore  72 . 
     After the cutting bit holder  54  has been fully inserted into the cutting bit holder bore  72 ,  FIG. 10  illustrates the relationship between the camming section  178  of the threaded camming pin and the walls of the slot. At this stage in the assembly process, the operator will draw the shank section  110  of the cutting bit holder  54  into tight engagement within the cutting bit holder bore  72  of the support block  50 . The operator achieves this through rotation of the threaded camming pin  170 . 
     More specifically, referring to  FIGS. 10 and 11 , the operator rotates the threaded camming pin  170  in the clockwise direction (see the arrow marked CW in  FIG. 11 ) as viewed in  FIG. 11  until the edge  184  of the notch  180  contacts (or engages) the side surface  146  of the notch  130 . The engagement occurs because the maximum transverse dimension for diameter “W” of the camming section  178  is greater than the width V of the slot  130 . Thus, during the clockwise rotation of the threaded camming pin  170  there is a position in which the camming section  178  engages the slot wall  146 . Here, this position occurs when edge  184  contacts of the wall  146 . 
     As the operator continues to rotate the threaded camming pin  170 , the camming section  178  continues to engage the slot wall  146  thereby forcing or moving the cutting bit holder  54  in a direction (see the arrow “S” in  FIGS. 2 and 11 ) toward the support block  50 . Finally, the threaded camming pin  170  is rotated to a point where the cutting bit holder  54  is firmly and securely retained to the support block  50 . 
     When the cutting bit holder  54  is secured to the support block  50 , there most likely will be a time when the operator will want to disconnect these two components. The operator can rotate the threaded cam pin  170  in the counter-clockwise direction (see the arrow CCW in  FIG. 9 ) as viewed in  FIG. 9 . Such counterclockwise rotation will cause the camming section  178  to disengage the slot surface  146 , move into the neutral position as shown in  FIG. 10 , and then rotate into the position shown in  FIG. 9 . In the position shown in  FIG. 9 , the edge  186  engages the slot surface  146 . As the operator continues to rotate the threaded camming pin  178  in the counterclockwise direction, the camming section  178  continues to engage the slot wall  146  to force or move the cutting bit holder  54  in the direction (see the arrow “T” in  FIG. 2  and  FIG. 9 ) away from the support block  50 . Such movement essentially disengages the cutting bit holder  54  from the support block  50  to the extent that the operator can disconnect these components by any commonly used means such as, for example, an impact on the cutting bit holder from a hammer. 
     In light of the above description of the assembly and disassembly of the cutting bit holder to the support block, it is thus apparent that the retention pin can be selectively in different positions. On one position, the retention pin is in a non-retaining position wherein the retention pin does not engage the slot surface. The retention pin can be is a retaining position in which the retention pin engages the slot surface to urge the cutting bit holder into the cutting bit holder bore. The retention pin can be in an ejecting position in which the retention pin engages the slot surface to urge the cutting bit holder out of the cutting bit holder bore. 
     There is the contemplation that one could use a set screw or the like in place of the threaded camming pin as the retention pin. However, if this were the case, the set screw would be of a length to extend to engage the surface that defines the central longitudinal bore  140  in the shank section  110 . Such engagement would retain the cutting bit holder in the cutting bit holder bore of the support block. As an alternative, the set screw would present a geometry to engage the side slot walls to retain the cutting bit holder in the cutting bit holder bore of the support block. 
     There is now an appreciation that during operation of the mining or construction machine, the support block experiences wear due to exposure thereof to the cutting debris. The use of the cutting bit holder increases the overall useful life of the support block. By doing so, there is less time spent on replacing support blocks, which results in an overall savings for the operator. The present invention thus provides a significant advantage to the operator. 
     There is also the appreciation that the present cutting bit holder securely mounts in the support block to minimize movement of the cutting bit holder in order to maximize the useful life of the cutting bit. Such a secure connection also is resistant to vibratory loosening, which could likewise lead to premature cutting bit wear and failure. It is apparent that the present invention provides a significant advantage to the operator. 
     Referring to  FIGS. 12-18 , there is illustrated another specific embodiment of a retention assembly for a cutting bit (or cutting tool). The retention assembly is a tool holder-base assembly designated by brackets as a  399 . This embodiment of the tool holder-base assembly provides certain advantages as set forth below. 
     During operation of the road milling machine, the base (or support block) experiences wear due to exposure thereof to the cutting debris. Over time, wear and other kinds of abuse causes the base to be ineffective which signals an end to its useful life. Once this occurs, the operator must cut or torch the base off the drum to allow for replacement of the base. Typically, the operator welds the replacement base to the drum. As the skilled artisan appreciates, it is time-consuming and hence costly, to remove and replace a base. Thus, there is an advantage to be able to prolong the useful life of the base. The present invention, including the specific embodiment of  FIGS. 12-17 , provides for that advantage. 
     Further, the cutting tools and cutting tool holders are subjected to considerable stresses during road milling operations. Accordingly, there is a desire to mount the cutting tool holder in the base to minimize movement of the cutting tool holder in order to maximize the useful life of the cutting tool. It is also important that the mounting between the cutting tool holder and the base be resistant to vibratory loosening which could likewise lead to premature cutting tool wear and failure. The present invention, including the specific embodiment of  FIGS. 12-18 , provides a secure mounting of the cutting tool holder to the base that is resistant to vibratory loosening. 
     Tool holder-base assembly  399  comprises a base generally designated as  400 . The base  400  has an arcuate surface  402  by which one can attach (for example, by welding) the base  400  to the surface of a driven member (for example, a road milling drum). Base  400  further comprises a leading base surface  404 , a trailing base surface  406 , one side base surface  408 , another side base surface  410 , and a top base surface  414 . Although the base  400  is not shown attached to the driven member, the direction of the rotation is shown by arrow “RR” in  FIG. 12 . 
     A collar  416  extends away from the top base surface  414 . A tool holder bore  418  travels through the base  400 . The collar  416  surrounds the bore  418  at the leading open end  420  thereof. The bore  418  further has a trailing open end  422 . The bore  418  presents a tapered, frusto-conical bore surface  424 . The bore  418  has a central longitudinal axis AA-AA. The half angle of taper (BB-BB) of the bore surface  424  is equal to between about 2½ degrees and about 5½ degrees with the preferred half-angle being equal to about 5½ degrees. 
     There should be an appreciation that the base  400  further contains a transverse passage  430 . The central longitudinal axis CC-CC of the transverse passage  430  is generally perpendicular (ninety degrees) to the central longitudinal axis AA-AA of the tool holder bore in the base  400 . Transverse passage  430  passes from one side base surface  408  to the other side base surface  410 . Transverse passage  430  intersects the bore  418  at a location so as to create an open elongate slot  431  in the surface  424  of the bore  418 . The transverse passage  430  has a threaded portion  432  that extends from the one side base surface  408  a pre-determined distance toward the tool holder bore  418 . The remainder of the transverse passage  430  is threaded, which includes all of the transverse passage  430  between the other side base surface  410  and the tool holder bore  418 . 
     A threaded cam pin  670  passes into the transverse passage  430  in a fashion as described hereinafter. As also described hereinafter, an operator can operate the threaded cam pin  670  to tighten (or help tighten) the attachment between the tool holder  500  and the base  400 . An operator can operate the threaded cam pin  670  to disengage (or help disengage) the tool holder  500  from engagement with the base  400 . The operation of the threaded cam pin  670  is described hereinafter, 
     Referring to the drawings, and especially the drawing of the tool holder  500  in  FIG. 12 ,  FIG. 17  and  FIG. 18 , there is illustrated a tool holder generally designated as  500 . The tool holder  500  has a head region  502  and an integral shank region  504 . The head region  502  is axial forward of the shank region  504 . The head region  502  contains a rotatable cutting tool bore  506 . The rotatable cutting tool bore  506  has an axial forward end  508  and an axial rearward end  510 . The head region  502  has a leading surface  512  adjacent the bore  506  and a trailing surface  514  adjacent the bore  506 . The head region  502  also has a leading protective surface  516  and a corresponding trailing surface  518 . As understood by those of ordinary skill in the art, the bore  506  typically receives a rotatable cutting tool therein. As mentioned hereinafter, an exemplary cutting tool is shown and described in U.S. Pat. No. 4,497,520 to Ojanen. 
     The head region  502  contains a positioning bore  550  that has a mediate threaded cylindrical surface  552 . The positioning bore  550  has a forward end  556  and a rearward end  558 . The bore  550  further includes a smooth forward region  590  that extends between the forward end  556  and the mediate threaded surface  552 , as well as a smooth rearward region  592  that extends between the rearward end  558  and the mediate threaded surface  552 . As will be described in more detail hereinafter, the threaded bore  550  is adapted to receive the threaded section of an installation-removal tool  600 . The operator can use the installation-removal tool  600  to better position the tool holder  500  in relation to the base  400  in both the attachment of the tool holder to the base and the detachment of the tool holder  500  from the base  400 . There should be an appreciation that the bore  550  may be partially threaded or it may be fully threaded. In other words, substantially all of the surface of the bore  550  may be threaded. 
     The shank region  504  projects from the trailing surface  518  of the head region  502 . The shank region  504  has a leading end  522  and an opposite distal trailing end  524 . The shank region  504  has a central longitudinal axis EE-EE. The shank region  504  present an alignment region  528  defined by a flat surface  530 . The flat surface  530  is of a depth “ZZ” (see  FIG. 13B ). The alignment region  528  has a stop  560  at the axial forward end thereof. The shank region  504  contains an elongate slot  562  in the flat surface  530  thereof. 
     The threaded cam pin  670  has an end  672  and an opposite end  674 . The threaded cam pin  670  has a threaded section (bracket  676 ) and a smooth camming section (bracket  678 ) that does not have threads and another threaded section (bracket  691 ). The camming section  678  is generally cylindrical in geometry, except that an arcuate notch  682  is in the camming section  678 . The arcuate notch  682  travels the axial length of the camming section  678 . A pair of edges  684 ,  686 , which are opposite one another, define the periphery of the arcuate notch  682 . As shown in  FIGS. 15A and 15B , a straight line or chord XX-XX passes through the opposite edges  684 ,  686 . 
     As is apparent from a consideration of the drawings, the threaded cam pin  670  threads into the threaded portion  432  of the transverse passage  430  whereby the camming section  678  extends into the cutting bit holder bore  418 . The threaded cam pin  670  functions as an alignment guide for the insertion of the cutting tool holder  500  when it extends into the cutting tool holder bore  418 . Thus, as mentioned above, the camming section  678  extends completely across the tool holder bore  418 . 
     In regard to the assembly of the cutting tool  500  to the base  400 , one inserts the shank region  504  of the cutting tool holder  500  into the tool holder bore  418  (of the base  400 ) as the first step to attaching (or connecting) the tool holder  500  to the base  400 . To engage the tool holder  500 , the operator takes the installation removal tool  600  and inserts the threaded region  612  into the bore  550 . The operator then threads the threaded region  612  into mediate threaded surface  552 . Once the threaded connection is secure, the operator can then transport or position the tool holder  500  to align and then attach the tool holder  500  to the base  400 . After the tool holder  500  attaches to the base  400 , the operator can then unthreaded the installation-removal tool  600  from the threaded bore  550 . 
     One can achieve correct relative alignment between the tool holder  500  and the base  400  when the threaded cam pin  670  has an orientation so that the chord XX-XX is generally parallel to the flat surface  530  of the tool holder  500 .  FIG. 13A  illustrates this orientation of the tool holder  500  relative to the base  400 . A more detailed discussion about the relative alignment between the tool holder  500  and the camming section  678  is set forth below. 
     As one can appreciate, for the shank region  504  of the tool holder  500  to enter the tool holder bore  418 , the threaded cam pin  670  must present the neutral orientation such as is shown in  FIG. 13A . More specifically, the threaded cam pin  670  is threaded into the threaded portion  432  of the transverse passage  430  so that the threaded cam pin  670  satisfies two conditions. One such condition is that the camming section  678  extends into and through the tool holder bore  418  and into the unthreaded portion of the transverse passage  430 . The second condition is that the camming section  678  has an orientation as illustrated in  FIG. 13A  so that the chord (i.e., the straight line XX-XX) between the opposite edges  684 ,  686 , is generally parallel to the flat surface  530 . When in this condition, the threaded camming pin  670  provides an alignment feature to align correctly the tool holder  500  with the base  400 . 
     When the camming section  678  presents the orientation of  FIG. 13A , the chord XX-XX is spaced from the flat surface  530  a distance YY (see  FIG. 13B ). Further, the minimum distance BBB the camming section  678  extends past the surface  424  of the bore  418  is less than the depth ZZ of the alignment region  528 . As mentioned above, the camming section  678  extends into the tool holder bore  418 . This orientation provides an alignment feature because the tool holder  500  can slide past the camming section  678  and into the tool holder bore  418  only when the flat surface  530  is oriented in a generally parallel fashion to the camming section  678 . If one tries to move the shank region  504  of the tool holder into the tool holder bore  418  in another orientation, the shank region  504  abuts against the camming section  678 .  FIG. 14  shows the abutment of the shank region  504  against the camming section  678 . The abutment prevents any further insertion of the shank region  504  of the tool holder  500  into the tool holder bore  418  of the base  400 . 
     After the tool holder  500  has been fully inserted into the tool holder bore  418 ,  FIG. 13A  illustrates the relationship between the camming section  678  of the threaded cam pin  670  and the flat surface  530  of the shank region  504 . At this stage in the assembly process, through rotation of the threaded camming pin  670 , the operator will draw (or help draw) the shank region  504  of the tool holder  500  into tight engagement within the tool holder bore  418  of the base  400 . 
     More specifically, referring to  FIGS. 13A through 13D , the operator rotates the threaded cam pin  670  in the clockwise direction (see the arrow marked CCWW in  FIG. 13A ) as viewed in  FIG. 13C  until the edge  686  of the notch  682  contacts (or engages) the flat surface  530  of the shank. At this position, the threaded cam pin  670  is in initial contact with the flat surface  530  of the shank region  504 .  FIG. 13C  illustrates the threaded cam pin  670  in this position. The engagement occurs because the maximum distance “AAA” (see  FIG. 13B ) the camming section  678  could extend past the surface  424  of the bore  418  is greater than the depth “ZZ” of the flat surface  530 . Thus, during the clockwise rotation of the threaded camming pin  670 , there is a position in which the camming section  678  engages initially the flat surface  530 . Here, this position occurs when edge  686  first contacts of the flat surface  530  (see  FIG. 13C ). 
     As the operator continues to rotate the threaded cam pin  670  in the clockwise direction, the camming section  678  continues to engage the flat surface  530  thereby forcing or moving the tool holder  500  in a direction (see the arrow “SS” in  FIG. 13D ) toward the base  400 . Finally, the threaded cam pin  670  is rotated to a point where the tool holder  500  is firmly and securely retained to the base  400  as shown in  FIG. 13D . 
     When in the condition shown in  FIG. 13D , the tool holder-base assembly  399  is in a condition suitable for operation. When in this position, the tool holder  500  is tightly engaged to the base  400 . The tight engagement causes there to be minimal movement between the cutting tool holder and the base to maximize the useful life of the cutting tool. The tight engagement also makes the connection of the tool holder to the base to be resistant to vibratory loosening which could likewise lead to premature cutting tool wear and failure. 
     During the operation of the road milling machine, there typically will come a time when it is desirable to detach the tool holder  500  from the base  400 . This could be due to any one of a number of circumstances. For example, the tool holder  500  could wear to the point where replacement is necessary. The same could be true for the base in that it could wear to the point requiring replacement. The disconnection of the tool holder  500  from the base  400  is relatively easy and quick as described hereinafter. 
     To disconnect the tool holder  500  from the base  400 , the operator can rotate the threaded cam pin  670  in the counter-clockwise direction (see the arrow CCCWW in  FIG. 13E ) as viewed in  FIG. 13E . Initially, such counterclockwise rotation will cause the camming section  678  to move from the position shown in  FIG. 13D  so as to disengage the flat surface  530 , and then move into the neutral position as shown in  FIG. 13A . 
     Once the threaded cam pin  670  is in the neutral position, the operator can then rotate the threaded cam pin  670  in the counterclockwise direction into the position shown in  FIG. 13E . In the position shown in  FIG. 13E , the edge  684  make initial disengagement contact with the flat surface  530 . As the operator continues to rotate the threaded cam pin  678  in the counterclockwise direction, the camming section  678  continues to engage the flat surface  530  to force or move the tool holder  500  in the direction (see the arrow “TT” in  FIG. 13E ) away from the base  400 . Such movement essentially disengages the tool holder  500  from the base  400 .  FIG. 13F  illustrates the disengagement of the tool holder  500  from the base  400 . The position of the threaded cam pin  670  as shown in  FIG. 13F  is the result of additional counterclockwise rotation of the threaded cam pin  670  from the position shown in  FIG. 13E  to the position shown in  FIG. 13F . The extent of the disengagement is such that the operator can disconnect these components by any commonly used means such as, for example, an impact on the cutting bit holder from a hammer. 
     The operator can also use the installation-removal tool  600  to assist with the detachment of the tool holder  500  from the base  400 . Referring to  FIG. 19 , the installation-removal tool  600  has a shaft  602  with opposite ends  604  and  606 . A handle  610  is at the one end  604  and a threaded portion  612  is at the other end  606  of the shaft  602 . To help remove the tool holder  500  from the base  400 , the operator can thread the threaded portion  612  of the tool  600  into the threaded bore  550  in the tool holder  500  and threadedly engage the threaded surface  552 . Once the threaded connection is secure, the operator can assist in the positioning (e.g., removal or installation) of the tool holder  500  relative to the base  400 . 
     The specific embodiment of the tool holder-base assembly  399  as illustrated in  FIGS. 12 through 18  has a number of advantages as will become apparent. One such advantage is the secure connection between the cutting tool holder and the base that minimizes movement of the cutting tool holder in order to maximize the useful life of the cutting tool. Another advantage is the secure connection that makes the connection resistant to vibratory loosening which could likewise lead to premature cutting tool wear and failure. 
     Referring to  FIGS. 20-21 , there is illustrated a specific embodiment of the tool holder-base assembly generally designated as  900 . The tool holder-base assembly  900  comprises a base  904  and a sleeve  902 . The base  904  contains a bore  906  that receives the sleeve  902 . The base  904  further contains a transverse passage (or bore)  910  that receives a threaded camming pin (not illustrated). The sleeve  902  comprises a head region  920  and a shank region  922 . The shank region  922  has a surface  924  at the rearward end thereof. 
     In operation, the transverse passage  910  receives the threaded camming pin that functions in a manner relative to surface  924  like that of threaded camming pin  670  relative to surface  530 . 
     The patents and other documents identified herein are hereby incorporated by reference herein. Other embodiments of the invention will be apparent to those skilled in the art from a consideration of the specification or a practice of the invention disclosed herein. It is intended that the specification and examples are illustrative only and are not intended to be limiting on the scope of the invention. The true scope and spirit of the invention is indicated by the following claims.