Patent Publication Number: US-5833323-A

Title: Cutting toolholder retention system

Description:
TECHNICAL FIELD 
     This invention relates to excavation cutting tools, and more particularly to a retention system for retaining an excavation cutting toolholder in a support block during use. 
     BACKGROUND ART 
     Excavation cutting tool assemblies for such applications as continuous mining or road milling typically comprise a cutting tool, sometimes referred to as a cutting bit, rotatably mounted within a support block. The support block in turn is mounted onto a drum or other body, typically by welding, which in turn is driven by a suitable power means. When a number of such support blocks carrying cutting tools are mounted onto a drum, and the drum is driven, the cutting tools will engage and break up the material which is sought to be mined or removed. The general operation of such a mining or construction machine is well known in the art. 
     Because the support block is exposed, it is subject to wear and abuse and must be cut or torched off the drum and replaced when unusable. In order to prolong the life of the support block, a cutting toolholder, sometimes referred to as a cutting tool sleeve, bit holder, or bit sleeve, is sometimes employed. The cutting tool is rotatably or otherwise releasably mounted within the bit holder which in turn is mounted within the support block via some mechanical connection. This helps to protect the support block from abuse and wear, thus minimizing or eliminating the down time periods otherwise required for drum repair. The use of such bit holders is well known in the art. For example, U.S. Pat. No. 5,067,775 to D&#39;Angelo discloses the use of such a bit holder which is referred to as a sleeve in that patent. 
     It is well known that such cutting tools and cutting toolholders are subjected to considerable stresses during mining or other operations. Accordingly, it is desirable that the cutting toolholder be mounted to the support block in such a manner as to minimize movement of the cutting bit holder in order to maximize the life of the cutting tool. It is also important that the mounting between the cutting toolholder and the support block be resistant to vibratory loosening which could likewise lead to premature cutting tool wear and failure. Various methods have been proposed or used in the past to mount a cutting tool sleeve within a support block in an attempt to minimize cutting toolholder movement or loosening, while maximizing cutting tool life. 
     For example, U.S. Pat. No. 3,749,449 to Krekeler discloses a support block having two upstanding members or bifurcations which define therebetween a channel into which fits a toolholder. A pin passes through the support block and the cutting toolholder and releasably secures the toolholder to the support block. The Krekeler patent relies on cooperation between the bottom surface of the cutting toolholder and an upper surface of the support block, at the bottom of the channel, to resist forces tending to pivot the cutting toolholder about the pin. In other words, the Krekeler patent relies upon a close tolerance fit to minimize rotational movement of the cutting tool and cutting toolholder about the pin during use. Otherwise, movement of the cutting toolholder in the support block will cause unnecessary wear to the cutting tool, the cutting toolholder, and the support block. 
     Alternatively, U.S. Pat. No. 4,650,254 to Wechner discloses the use of two bolts to connect a cutting toolholder to a block. The two bolts pass horizontally through the rear surface of the support block and through the shank portion of the cutting toolholder. Such a connection may be subject to vibratory loosening. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an improved excavation cutting toolholder retention system which allows a cutting toolholder to be securely fastened to a support block in such a manner as to minimize or eliminate any movement or loosening of the cutting holder within the support block. 
     In carrying out the above objects, and other objects and features of the present invention, an improved excavation cutting toolholder retention system is provided. The improved excavation cutting toolholder retention system comprises a cutting toolholder having a flange recess and a holder engagement surface. The system also includes a support block having a toolholder bore into which the cutting toolholder is inserted and a block pin bore intersecting the toolholder bore, the block pin bore defining a block engagement surface which is inclined downwardly relative to the toolholder bore. The system further includes a pin having a pin shaft, the pin shaft having a pin flange, the pin flange engaging the flange recess so as to limit translational movement of the pin shaft. The pin engages the block engagement surface and the holder engagement surface such that the pin may be moved to draw the cutting toolholder into the toolholder bore. 
     In a preferred embodiment, the support block has block pin bores which define the block engagement surface and are inclined downwardly. The holder engagement surface of the cutting toolholder is a transverse pin bore. The pin runs through and engages the transverse pin bore of the cutting toolholder. The pin has a pin shaft, a first jam member, and a second jam member, the first and second jam members each having a block engagement portion which moveably engages the block pin bores. The pin shaft also has a pin flange which engages the flange recess so as to limit translational movement of the pin shaft within the transverse pin bore. At least one of the first and second jam members is moveable along the pin shaft relative to the other of the first and second jam members such that the block engagement portion of the first and second jam members is moved along the block pin bores and the cutting toolholder is drawn into the toolholder bore. 
     In a more preferred embodiment, the pin shaft has a threaded portion and one of the first and second jam members has a threaded jam bore such that one of the first and second jam members may threadably engage the pin shaft and be moved relative to the other of the first and second jam members. Furthermore, the first jam member may have a first aligned cylindrical portion and a first angled cylindrical portion and the second jam member may have a second aligned cylindrical portion and a second angled cylindrical portion such that the first and second aligned cylindrical portions engage the transverse pin bore of the cutting toolholder and the first and second angled cylindrical portions define the block engagement portion and engage the block pin bores. 
     In another more preferred embodiment, the cutting toolholder has a holder slot intersecting the transverse pin bore such that the cutting toolholder may be removed from the toolholder bore of the support block by moving the second jam member relative to the first jam member such that the first and second jam members do not interfere with the transverse pin bore and the cutting toolholder may be withdrawn from the toolholder bore while the first and second jam members still moveably engage the block pin bores. 
     In a more preferred embodiment applicable to all preceding embodiments, the toolholder has a holder shoulder and the support block has a seating shoulder region adjacent the toolholder bore. When the cutting toolholder is drawn into the toolholder bore as described, the holder shoulder will abut the seating shoulder region. 
     In another preferred embodiment applicable to all preceding embodiments, the pin shaft has a pin shaft axis and a pin shaft diameter and the pin flange is a cylindrical portion about the pin shaft axis, the cylindrical portion having a cylindrical portion diameter greater than the pin shaft diameter. In another preferred embodiment applicable to all preceding embodiments, the flange recess is a pin flange slot which intersects the transverse pin bore. 
     The present invention also includes an improved cutting toolholder for use with a support block and pin, the support block having a toolholder bore into which the cutting toolholder is inserted and block pin bores inclined downwardly, the pin having a pin shaft, a first jam member, and a second jam member moveable along the pin shaft relative to the first jam member, the pin shaft having a pin flange, and the first and second jam members moveably engaging the block pin bores. The improved cutting toolholder comprises an outer wear region and a shank portion, the shank portion having a transverse pin bore which is substantially aligned with the block pin bores when the shank portion is inserted into the toolholder bore such that the pin can run between the block pin bores through the transverse pin bore. The transverse pin bore defines a flange recess which engages the pin flange so as to limit translational movement of the pin shaft within the transverse pin bore. The first and second jam members engage the block pin bores and the transverse pin bore such that moving the second jam member relative to the first jam member will draw the shank portion into the toolholder bore of the support block. 
     In a preferred embodiment, the shank portion of the cutting toolholder has a holder slot such that the shank portion may be removed from the toolholder bore of the support block by moving the second jam member relative to the first jam member such that the first and second jam members no longer interfere with the transverse pin bore and the shank portion may be withdrawn from the toolholder bore such that the first and second jam members still engage the block pin bores. 
     In another preferred embodiment, the flange recess is a pin flange slot which intersects the transverse pin bore. More preferably, the pin flange slot perpendicularly intersects the transverse pin bore. 
     The present invention also includes a pin for use with a support block and a cutting toolholder, the toolholder having a transverse pin bore defining a flange recess, the support block having a toolholder bore into which the cutting toolholder is inserted and block pin bores inclined downwardly to and intersecting the transverse pin bore. The improved pin comprises a pin shaft having a first pitch threaded portion, a pin flange, and a second pitch threaded portion, a first jam member having a first aligned cylindrical portion, a first angled cylindrical portion, and a first threaded jam bore, a second jam member having a second aligned cylindrical portion, a second angled cylindrical portion, and a second threaded jam bore. The first threaded jam bore threadably engages the first pitch threaded portion of the pin shaft and the second threaded jam bore threadably engages the second pitch threaded portion of the pin shaft such that the first and second aligned cylindrical portions may engage the transverse pin bore, the pin flange may engage the flange recess so as to limit translational movement of the pin shaft within the transverse pin bore, and the first and second angled cylindrical portions may engage the block pin bores such that rotating the pin shaft will move the first jam member relative to the second jam member and draw the cutting toolholder into the toolholder bore of the support block. 
     In a more preferred embodiment, the first and second angled cylindrical portions have a mating groove. In another preferred embodiment, the pin shaft has a pin shaft axis and a pin shaft diameter and the pin flange is a cylindrical portion about the pin shaft axis, the cylindrical portion having a cylindrical portion diameter greater than the pin shaft diameter. 
     The advantages resulting from this invention are numerous. For example, by having the block pin bores inclined downwardly, the cutting toolholder will be drawn into an especially tight relationship with the toolholder bore. This tight fit is especially secure if one or both of the shank portion or toolholder bore is tapered so that the shank portion of the cutting tool is wedged into the toolholder bore when the components are engaged by utilizing the pin. The security of the fit is also increased if the toolholder has a holder shoulder which abuts a seating shoulder region of the support block when the cutting toolholder is drawn into the toolholder bore. 
     Another advantage of this present invention is that the toolholder bore of the support block may have a configuration so as to completely surround and provide multi-directional support to the cutting toolholder. 
     As a further advantage, when the toolholder is worn, it is easily removed and changed by simply loosening the pin. 
     Furthermore, because the pin flange resides within the flange recess of the cutting toolholder during use, translational movement of the pin shaft is limited. As a result, binding of the first and second jam members will be reduced or prevented and the jam members will be kept at approximately the same distance from the center of the pin during loosening so to help ensure easy removal of the cutting toolholder. 
     Further objects and advantages of this invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown. 
    
    
     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 support block, cutting toolholder, and cutting tool showing one embodiment of the invention; 
     FIG. 2 is a sectional view taken along the plane indicated by line 2--2 in FIG. 1, the left half showing the invention in the loose condition and the right half showing the tightened condition; 
     FIG. 3 is a side view of the shank portion of the cutting toolholder showing the holder slot; 
     FIG. 4 is a side view of the shank portion of the cutting toolholder showing the pin slot; 
     FIG. 5 is a side view of a threaded pin; 
     FIG. 6 is a side view of a first jam member; and 
     FIG. 7 is a side view of a second jam member. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     One embodiment of the cutting toolholder retention system 100 is shown in FIGS. 1 and 2. The cutting tool retention system 100 includes a support block 102 having a toolholder bore 104 and block pin bores 106 and a cutting toolholder 108 having a holder shank portion 110 mated to the support block 102 via a pin 112. In the embodiment shown, a cutting tool 114 may be rotatably and releasably mounted within the cutting toolholder 108. However, the scope of this invention would cover cutting toolholder retention systems in which the cutting tool is non-rotatably mounted. 
     In use, such support blocks 102 can be distributed over and fastened to, such as by welding, the circumference and length of a drum or other body (not shown) according to any desired pattern. The drum or other body may be driven by any conventional and suitable power means to cause the cutting tools 114 to engage and break up material that they are applied to. Such applications are well known in the art, and will not be described further here. 
     The cutting tool 114 typically has an elongated body. The cutting end 120 of the cutting tool 114 typically comprises a hard cutting insert 122 mounted onto a generally conical outer region 124. This hard cutting insert 122 may be made from cemented tungsten carbide or any other suitable material. The hard cutting insert 122 is generally mounted at the end of the conical outer region 124 where the cutting insert 122 may be brazed or otherwise suitably fastened into place. The cutting tool 114 also includes a tool shank 126 adjoining a shoulder 128 of the conical outer region 124. Because such cutting tools are generally known in the art, they need not be described in further detail here. 
     Cutting toolholders may have a variety of configurations. The cutting toolholder 108 shown in this embodiment has an outer wear region 130 and the shank portion 110 joined at a holder shoulder 132. The cutting toolholder 108 defines a tool bore 134 in which the cutting tool 114 may be rotatably or otherwise mounted. Such rotatable or non-rotatable mountings are well known in the art, and will not be described in further detail here. 
     While the shank portion 110 of the cutting toolholder 108 may have a variety of configurations, the shank portion 110 as shown in this embodiment is tapered along a center axis &#34;A&#34;. The shank portion 110 may be made of solid material, or as shown here, may have a cavity such as a vertical bore 136. The shank portion 110 also has a holder engagement recess which in this embodiment comprises a transverse pin bore 138. The transverse pin bore 138 in this embodiment is cylindrical and aligned along a center axis designated &#34;B&#34; and which preferably intersects the center axis &#34;A&#34; of the shank portion 110. The holder engagement recess has a holder engagement surface 140 which in the embodiment shown is the surface defined by the transverse pin bore 138, especially the lower surface when locking the toolholder 108 and the upper surface when releasing the toolholder 108. 
     As best shown in FIG. 3, the holder shank portion 110 defines a holder slot 142 defined by two vertical slot sides 144 which intersect the transverse pin bore 138. As best shown in FIGS. 2 and 3, on each end of the transverse pin bore 138 the holder shank 110 also defines jam recesses 146 having vertical recess walls 148. As best shown in FIG. 4, the holder shank 110 additionally defines a pin flange recess which in this embodiment is a pin flange slot 150. The pin flange slot 150 in this embodiment is defined by two vertical slot sides 152 and perpendicularly intersects the transverse pin bore 138. In this embodiment, the two vertical slot sides 152 have chamfers 153 at the lower end of the holder shank portion 110. 
     The support block 102 typically has the toolholder bore 104 surrounded by a seating shoulder region 160. The toolholder bore 104 in this preferred embodiment is tapered so as to match the taper of the shank portion 110 of the cutting toolholder 108. It has been found preferable that the maximum total included taper angle be approximately 16°. 
     The support block 102 also has a side surface 162 and a base 164 which may be mounted to a drum or other body (not shown) by way of welding or any other suitable method. 
     The toolholder bore 104, and accordingly the cutting toolholder 108 and the cutting tool 114, is typically pitched in the direction of travel of the cutting tool 114, designated as direction &#34;C&#34; in FIG. 1. 
     As shown in FIGS. 1 and 2, the toolholder bore 104 of the support block 102 may be partially surrounded but is more typically fully surrounded by a seating shoulder region 160. The toolholder bore 104 of this embodiment has a holder bore center axis &#34;A&#39;&#34; which coincides with the axis &#34;A&#34; of the shank portion 110 of the cutting toolholder 108 when the components are assembled as shown. 
     Furthermore, the support block 102 has the block pin bores 106, which are cylindrical and aligned along block pin bore axes designated &#34;D.&#34; As shown in FIG. 2, the block pin bore axes &#34;D&#34; intersect the axis &#34;B&#34; of the transverse pin bore 138 at an angle &#34;E.&#34; 
     The block pin bores 106 have a block engagement surface 165, which in the embodiment shown is the surface defined by the block pin bores 106, especially the upper surface when locking the toolholder 108 and the lower surface when releasing the toolholder 108. As shown in FIG. 2, the block engagement surface 165, and in this embodiment the block pin bores 106 having axes &#34;D,&#34; are inclined downwardly relative to the toolholder bore 104. 
     As best shown in FIGS. 1 and 2, the block pin bores 106 also define pin bore grooves 166 along the lower surface of the pin bores 106. The pin bore grooves 166 in this embodiment are semi-cylindrical in shape. Mating pins 170 having a cylindrical configuration reside within the pin bore grooves 166. The mating pins 170 may be press fit into the pin bore grooves 166 in which case the pin bore grooves 166 will have a cross section configuration slightly greater than a half circle or may be held in position using any suitable fastening method such as by tack welding or epoxy adhesives. The mating pins 170 may be made of any suitable material, such as 52100 steel. 
     As shown in FIGS. 2, 5, 6, and 7, the pin 112 includes a pin shaft 180 having a pin shaft diameter, a first jam member 182 and a second jam member 184 which are assembled along the center axis &#34;B.&#34; The pin shaft 180 in this embodiment has a first pitch threaded portion 186, an unthreaded portion 188 including a pin flange 190 having pin flange sides 191, and a second pitch threaded portion 192. While the pin flange 190 is required in this embodiment, the pin shaft need not have an unthreaded portion. The pin flange 190 may have any suitable configuration as long as it has a greater diameter than the pin shaft 180 and will fit within the pin flange slot 150 of the holder shank 110. In the embodiment shown, the pin flange 190 is a cylindrical portion 193 about the pin shaft axis &#34;B&#34; and the cylindrical portion 193 has a cylindrical portion diameter greater than the pin shaft diameter. Furthermore, in the embodiment shown, the dimension between the pin flange sides 191 should be less than the dimension between the vertical slot sides 152 such that the pin shaft 180 may be rotated within the retention system 100 as will be explained. 
     While the first pitch threaded portion 186 is shown as being a left hand threaded portion and the second pitch threaded portion 192 is shown as being a right hand threaded portion, that need not be the case. While the threads may be made in any suitable manner, the first and second pitch threaded portions 186 and 192 may be cold rolled. The pin shaft 180 also has an engagement structure 194 which, in the embodiment shown, constitutes hexagonal recesses centered along the axis &#34;B&#34; of the pin shaft 180. 
     As shown in FIG. 6, the first jam member 182 has an aligned cylindrical portion 196 aligned along the axis &#34;B,&#34; the outer end of which has a chamfer 198, preferably at an angle of 45° to the axis &#34;B.&#34; Adjoining the aligned cylindrical portion 196 at a jam shoulder 200 is an angled cylindrical portion 202 having a center axis &#34;D&#34; set at an angle &#34;E&#34; to the axis &#34;B.&#34; 
     The first jam member 182 also defines a threaded jam bore 204 which, in the embodiment shown, constitutes a left hand threaded bore manufactured to threadably engage the first pitch threaded portion 186 of the pin shaft 180. 
     The first jam member 182 also defines a mating groove 206 along the lower surface of the angled cylindrical portion 202. In this embodiment, the mating groove 206 has a semi-cylindrical configuration designed to mate with the mating pin 170 as will be explained in further detail. 
     The jam 182 has a pin engagement surface 210. In the embodiment shown, the pin engagement surface 210 has a holder engagement portion 212 and a block engagement portion 214. In this embodiment, the holder engagement portion 212 is the outer surface, especially the lower surface when locking and upper surface when releasing, of the aligned cylindrical portion 196. The block engagement portion 214 is the outer surface, especially the upper surface when locking and the lower surface when releasing, of the angled cylindrical portion 202. 
     As shown in FIG. 7, the second jam member 184 is a mirror image duplicate of the first jam member 182. Like the first jam member 182, the second jam member 184 has an aligned cylindrical portion 196&#39;, a chamfer 198&#39;, and a jam shoulder 200&#39;, an angled cylindrical portion 202&#39;, a threaded jam bore 204&#39; which in the embodiment shown has a right hand thread manufactured to threadably engage the second pitch threaded portion 192 of the pin shaft 180. Like the first jam member 182, the second jam member 184 also has a pin engagement surface 210&#39; including a holder engagement portion 212&#39; and a block engagement portion 214&#39;. Also similar to the first jam member 182, the angled cylindrical portion 202&#39; of the second jam member 184 has an axis &#34;D&#34; set at an angle &#34;E&#34; to the center axis &#34;B&#34; of the aligned cylindrical portion 196&#39;. 
     Like the threaded shaft 180, while the first jam member 182 is shown as having a left hand threaded jam bore 204 and the second jam member 184 is shown as having a right hand threaded jam bore 204&#39;, that need not be the case. 
     To use the embodiment of this invention shown in FIGS. 1-7, the first or second jam member, 182 or 184, is partially threaded onto the first or second pitch threaded portion respectively, 186 or 192, of the pin shaft 180. The pin shaft 180, together with the one first or second jam member 182 or 184, is then inserted through the block pin bores 106 such that the mating groove 206 or 206&#39; of the first or second jam member, 182 or 184, is aligned roughly with the mating pin 170 of one of the block pin bores 106. 
     The other of the second or first jam member, 184 or 182, is then threaded onto the other of the second or first pitch threaded portion, 192 or 186, of the pin shaft 180 until the mating groove 206&#39; or 206 of the second or first jam member, 184 or 182, is roughly aligned with the mating pin 170 of the other one of the block pin bores 106. 
     An appropriate tool may then be used to engage the engagement structure 194 of the pin shaft 180 and rotate the pin shaft 180 appropriately such that the first and second jam members, 182 and 184, will be drawn towards each other. At the same time, the first and second jam members 182 and 184 must be maintained in position until the mating grooves 206 and 206&#39; engage the mating pins 170. As shown on the left half of FIG. 2, the pin shaft 180 may be rotated until the angled cylindrical portion 202 and 202&#39; of the first and second jam members, 182 and 184, reside partially within the block pin bores 106. 
     The holder shank portion 110 of the cutting toolholder 108 may then be inserted into the toolholder bore 104 of the support block 102 such that the pin shaft 180 will slide through the holder slot 142 into the transverse pin bore 138 of the cutting toolholder shank portion 110 and such that the pin flange 190 will slide into the pin flange slot 150. 
     At this point, and as shown on the left half of FIG. 2, the holder shank portion 110 of the cutting toolholder 108 will be loosely fitted within the toolholder bore 104 of the support block 102. Furthermore, at this point the pin flange 190 will reside within the pin flange slot 150 such that translational movement, such as lateral movement of the pin 112 along the axis &#34;B,&#34; will be limited by the dimensional tolerances between the pin flange 190 and the pin flange slot 150. 
     An appropriate tool may then again be used to engage the engagement structure 194 of the pin shaft 180 and rotate the pin shaft 180 appropriately such that the first and second jam members, 182 and 184, will be drawn towards each other. As the first and second jam members, 182 and 184, are drawn towards each other, the aligned cylindrical portions 196 and 196&#39; of the jam members, 182 and 184, will be forced into the transverse pin bore 138 aided by the chamfers 198 and 198&#39; on the ends of the jam members. At the same time, the rotation of the pin shaft 180 will cause the block engagement portions 214 and 214&#39; of the pin engagement surfaces 210 and 210&#39; of the angled cylindrical portions 202 and 202&#39; to travel along and engage the block engagement surfaces 165 of the block pin bores 106 such that the jam members will move in the direction marked &#34;F,&#34; as shown in FIG. 2. The pin flange 190 within the pin flange slot 150 will limit translational movement, such as lateral movement of the pin 112 along the axis &#34;B,&#34; such that the pin 112 will be maintained in a relatively centered relationship relative to axis &#34;A&#34; and such that binding of the first and second jam members 182 and 184 within the block pin bores 106 and the transverse pin bore 138 will be reduced or prevented. 
     At the same time, the holder engagement portions 212 and 212&#39; of the pin engagement surfaces 210 and 210&#39; of the jam members, 182 and 184, will engage the holder engagement surface 140 of the transverse pin bore 138 of the cutting toolholder shank portion 110 thereby forcibly wedging the cutting toolholder shank portion 110 of the cutting toolholder 108 in the direction marked &#34;G,&#34; as shown in FIG. 2, into a tight fitting relationship with the toolholder bore 104 of the support block 102 until the holder shoulder 132 abuts the seating shoulder region 160 as shown on the right half of FIG. 2. As shown on the right half of FIG. 2, the jam shoulder 200 may then protrude into the jam recess 146 of the cutting toolholder shank portion 110. 
     The cutting toolholder retention system 100 shown in FIGS. 1-7 should work satisfactorily when the transverse pin bore 138 of the cutting toolholder shank portion 110 has a diameter of 1.000&#34; to 1.00&#34;, the holder slot 142 has a dimension of 0.627&#34; to 0.630&#34; between the vertical recess walls 324, the pin flange slot 150 has a dimension of 0.2501&#34; to 0.255&#34; between the vertical slot sides 152, the block pin bores 106 have a diameter of 1.124&#34; to 1.125&#34; set at an angle &#34;E&#34; between 5°±10°&#39; and 80°±10°&#39;, the aligned cylindrical portion 196 and 196&#39; of the jam members 182 and 184 has a diameter of 0.998&#34; to 0.999&#34;, the angled cylindrical portion 202 and 202&#39; of the jam members has a diameter of 1.122&#34; to 1.123&#34; and is set at an angle between 50°±10°&#39; and 80°±10°&#39; so as to match the angle of the block pin bores 106, and the threaded jam bore 204 and 204&#39; constitutes a 37/64&#34; through hole, tapped to 5/8&#34;-24 thread, right or left handed as required, the pin flange 190 has a dimension of 0.240&#34; to 0.245&#34; between the pin flange sides 191, and the unthreaded portion 188 of the pin shaft 180 has a diameter of 0.54&#34; while the first and second pitch threaded portions 186 and 192 are 5/8&#34;-24 thread, left or right handed as required. All of the components may be made from any appropriate grade of steel, such as grade 4140 steel, 38-43 HRC. 
     Nylok® manufactured by Nylok Fastener Corporation, or any other suitable material or adhesive, may be employed to help prevent the pin shaft 180 from rotating during use and to help prevent the first and second jam members, 182 and 184, from loosening. 
     When it is desired to change the cutting toolholder 108, the pin shaft 180 is simply rotated in the opposite direction via the engagement structure 194 until the cutting toolholder shank portion 110 can be removed from the toolholder bore 104 and the pin shaft 180 via the holder slot 142. As shown on the left half of FIG. 2, the first and second jam members, 182 and 184, need not be removed from the pin shaft 180, and the mating grooves 206 and 206&#39; need not be disengaged from the mating pins 170, for the cutting toolholder 108 to be removed. 
     Advantages of this embodiment are that the matching cylindrical surfaces of the transverse pin bore 138 and the aligned cylindrical portions 196 and 196&#39; of the jam members, 182 and 184, together with the matching cylindrical surfaces of the block pin bores 106, and the corresponding angled cylindrical portions 202 and 202&#39; of the jam members, will provide a better contacting relationship between the engagement surfaces, thereby lowering contact stresses. Furthermore, because the pin flange 190 resides during use within the flange recess, the pin flange slot 150, translational movement, such as lateral movement of the pin shaft 180 along the axis &#34;B,&#34; is limited. As a result, binding of the first and second jam members 182 and 184 within the block pin bores 106 will be reduced or prevented as previously noted and the jam members 182 and 184 will be kept at approximately the same distance from the axis &#34;A&#34; during loosening of the retention system 100 so as to help ensure easy removal of the cutting toolholder 108. 
     Additionally, because the pin shaft 180 moves in the direction &#34;G&#34; as the cutting toolholder retention system 100 is tightened, a locking action is provided to restrain the system and help prevent undesired loosening. Similarly, during unlocking, the pin translates forward in a direction reverse of &#34;G,&#34; providing a &#34;bump off&#34; motion to the cutting toolholder 108 for easier disengagement. Yet another advantage is that the holder slot 142 in the cutting toolholder shank portion 110 allows the cutting toolholder 108 to be changed without the removal of any pins or screws from the support block 102. 
     All patents and patent applications cited herein are hereby incorporated by reference in their entirety. 
     While particular embodiments of the invention have been illustrated and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from this invention. It is intended that the following claims cover all such modifications and all equivalents that fall within the spirit of this invention.