Patent Publication Number: US-8528990-B2

Title: Cutter with diamond bit tip

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of application Ser. No. 12/357,916 filed Jan. 22, 2009, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     This invention generally relates to the field of rotary driven cylindrical cutter devices and scarifiers for use in roadway surface reclaiming, earthworking, milling, mining, or other in situ disintegration of hard materials. More particularly, the present invention is directed to cutter bit inserts for such rotary driven cylindrical cutter devices and scarifiers. 
     BACKGROUND OF THE INVENTION 
     In general, roadway surface milling, planing, or reclaiming equipment disclosed in the prior art includes a rotary driven cylindrical comminuting drum which acts to scarify and to mine the top portion of the asphaltic road surface in situ. Another application using a rotary driven cylindrical comminuting drum is coal mining. Coal mining machines with shearing drums are used rather widely in mining, particularly in underground mining of bituminous coal. Regardless of the application, the rotary driven drum may include flighting on the drum which acts to collect the mined or milled material or rubble toward the center of the drum where the material can be removed. In roadway surface milling, the rubble is then remixed with additional bituminous material and thereafter redeposited as a newly formed smooth asphaltic surface. In coal mining, the loosened coal rubble is collected onto a pan line, taking the coal to the conveyor belt for removal from the work area to the surface where the rubble is further processed. 
     In some prior art devices of this type, a plurality of cutter bit support members are connected to the curved surface of the drum or to the flighting by bolts or by weld. The plurality of the support members may be arranged end-to-end so as to form a substantially continuous helical pattern. The top surface of the helically arranged support members may be elevated above the curved surface of the drum. The top surfaces include angled openings into which conventional cutter bits are received. The cutter bits are generally a conical cutter with preferably a tungsten carbide tip or the like. Optionally, the support member may include an opening for receiving cutter bit insert that is removably mounted to the support member, for instance by threaded attachment. The insert has an opening for receiving the cutter bit and a gripping surface used for inserting and removing the cutter bit inserts with respect to the support members. 
     One example of a cutter bit insert is disclosed in U.S. Pat. No. 5,842,747 to Latham. Here, the insert includes a gripping surface, a conical shoulder, and a lower surface, defines an interior bore for receiving a cutter bit, and has external threads capable of threaded engagement with threads of a base portion. The gripping surface allows for easy access for removal of inserts. Threaded jamming fastener is also disposed in threaded engagement with threads of the base portion. The jamming fastener is initially positioned below the insert by use of an appropriate tool in the jamming fastener opening. After the insert is in place, the appropriate tool again is inserted in the jamming fastener opening and rotated to translate the jamming fastener toward the lower end of the insert until contact. Accordingly, the reverse is true when removing such insert from the base portion, especially when the insert is damaged. 
     Damage to the cutter bit inserts can be common. During use, abrasive forces, which often include rather substantial extreme sudden shocks, are transmitted to the cutter bits. Oftentimes, the forces are unevenly distributed between the cutter bits and inserts, which cause the cutter bits to vibrate and otherwise move and rotate within the support member opening or within the insert. Particularly in the presence of abrasive dust from the roadway surface reclaiming operation and the mining operation, the vibration and movement of the cutter bits act to enlarge the openings to such an extent that the cutter bits can be thrown out of the inserts. Indeed, depending on the abrasiveness of the mining surface, cutter bits can become damaged after about 4 hours to about 1 week of operation. It is desirable for the less expensive cutter bit to become damaged before the more expensive insert and even the more expensive and difficult to replace support member, in order to extend the life of the insert and the support member. 
     Unfortunately, in the event of damage to the insert or the support member, the mining machine must be stopped for a considerable length of time for repair. Repair and replacement of the insert damaged in this manner typically necessitates the use of an easy-out or similar removing tool in the field to remove the insert. Typically as a last resort, it becomes necessary to remove the support member portions, usually with the aid of a cutting torch, and to weld new support member portions in place. This is a time-consuming repair job which results in considerable expense to a mining machine operation, and results in a decreased rate in mining. 
     Despite the availability of such devices, there exists a need in the art for an apparatus having a cutter bit insert for a mining drum that is capable of removable attachment to a support member, yet is resistant to loosening upon rotation of the mining drum. There is also a need for an insert to wear before the support member in order to decrease the time and costs of repair and replacement. In particular, it becomes necessary to have a wear insert that is a sacrificial or expendable component relative to the more expensive support member. 
     SUMMARY 
     The present invention provides an apparatus for use on a portion of a mining drum that is adapted to be rotated in a cutting direction about a cylindrical axis defined by the mining drum. More specifically, in one embodiment the apparatus can include a base portion adapted to be mounted to the mining drum. The base portion can define an opening to receive a wear insert for retaining a cutter bit. The opening of the base portion can have a first seat, which may be conical, at an upper end and/or a lower end. The wear insert is engageable within the base portion opening and can include a gripping surface, flange, and a threaded portion. The gripping surface is preferably proximate the upper end of the base portion, while the flange, which may be conical, extends from the gripping surface to a middle portion. The threaded portion may extend from the middle portion to proximate the lower end of the base portion. The wear insert flange can frictionally engage with the first seat of the base portion opening. The wear insert can also define an interior bore for receiving at least one cutter bit at a fixed position relative to the wear insert. The interior bore can include a first portion having a cross-sectional area and a second portion having a cross-sectional area less than the cross-sectional area of the first portion to define a flange within the interior bore. In one example, the interior bore includes a step ring attached to the surface of the interior bore. The step ring can have an outer edge with a cross-sectional area substantially similar to the cross-sectional area of the interior bore and an inner edge with a cross-sectional area that is less than the cross-sectional area of the outer edge. The inner edge may have a lower portion that includes a chamfered edge. 
     The apparatus can further include a retainer having a threaded portion to threadably engage with the threaded portion of the wear insert. The conical shape of the flanges and seats of the wear insert and retainers can be substantially similar, being tapered at an angle in the range between about 10 degrees to about 70 degrees. The retainer is positioned and configured to engage the threaded portion and the side of the base portion facing away from the milled surface of the mining drum in order to reduce the amount of dust from entering the threads. Some embodiments include an expandable cylindrical sleeve disposed within the interior bore of the wear insert to frictionally engage with the cutter bit within the interior bore that can prevent the cutter bit from translating within the wear insert. The interior bore of the wear insert may include a protrusion to engage with a portion of the expandable sleeve to prevent rotatable movement of the expandable sleeve within the interior bore so that the cutter bit is retained at a fixed non-rotating position relative to the wear insert. 
     In another embodiment, the apparatus includes two retainers: an upper retainer and a lower retainer. The wear insert can include an interior bore to receive at least one cutter bit at a fixed position relative to the wear insert, a first portion proximate the upper surface of the base portion having a threaded portion and a second portion proximate the lower surface of the base portion having a threaded portion. A middle portion dimensioned to be received in the base portion opening can extend between the first and second portions. The upper retainer can have a gripping surface and a threaded portion threadably engageable with the threaded portion of the first portion of the wear insert. The gripping surface of the upper retainer can be configured to be rotated to engage and disengage the threaded portion of the upper retainer from the threaded portion of the first portion of the wear insert. The lower retainer can have a gripping surface and a threaded portion threadably engageable with the threaded portion of the second portion of the wear insert. The lower retainer can prevent the wear insert from translating longitudinally within the base portion. The gripping surface of the lower retainer can be configured to be rotated to engage and disengage the threaded portion of the lower retainer from the threaded portion of the second portion of the wear insert from the lower surface of the base portion. 
     Another embodiment of the apparatus for use on a portion of a milling or mining drum, adapted to be rotated in a cutting direction about a cylindrical axis defined by said drum is provided. The apparatus can include a base portion adapted to be mounted to the drum. The base portion can have an upper and lower surface, and an opening therebetween having a first seat proximate the upper surface. The apparatus can include an insert that is engageable with the base portion opening. The insert can include an interior bore to receive at least one cutter bit at a fixed position relative to the wear insert and an exterior surface. The cutter bit can have a cutting tip, a shank extending therefrom, and a threaded portion. The cutting tip can include a hardened tip comprising a hardened material attached to a substrate, such as diamond particles attached to a carbide substrate. The shank can include a transition disposed between the tip and the threaded portion. The transition can be tapered at various degrees, including a Morris taper. Optionally, the transition can be a polygonal shape, such as a hexagon for example. A portion of the exterior surface facing the base portion can be dimensioned to be received in the first seat of the base portion opening. A portion of the insert interior bore can be sized and shaped to engage securably with said transition of the cutter bit at a fixed position relative to the wear insert. The apparatus can include a retainer having a threaded portion to threadably engage with the threaded portion of the cutter bit. Because of the frictional engagement between the cutter bit and the insert and the insert and the base portion, the cutter bit is prevented from rotating during operation. Periodic manual rotation of the cutter bit can extend the life of the cutter bit by allowing wear to apply to several regions of the cutter bit. 
     One feature of an embodiment of the present invention is that the wear insert is capable of removable attachment to a base portion, yet resistant to loosening upon rotation of a mining drum. In some preferred embodiments, the opening is not tapped and the insert is locked within the opening with frictional engagement between the flange of the insert and the first seat and the retainer and the second seat of the opening. The non-tapped base portion opening eliminates the risk of damaged threads of the opening and the wear insert. 
     Another feature is that the cutter bit and/or the wear insert are designed to wear and fatigue more frequently than the base portion. This can decrease the time and costs of repair and replacement by allowing only the replacement of the less expensive cutter bit and/or wear insert. Further, some embodiments include inserts that are designed to wear and fatigue more frequently than the cutter bit. Some embodiments include configurations that substantially prevent the rotation of the cutter bit relative to the wear insert during operation. With the simplicity of the wear insert securably engaged with the base portion, and the seats and flanges provided therewith, the apparatus is durable and robust, yet easily and rapidly serviced. 
     Yet another feature of some embodiments of the present invention is the use of a cutter bit that includes a hardened tip that can include a diamond working end attached to a carbide substrate, the diamond working end having a pointed geometry. The diamond working end can comprise diamond, polycrystalline diamond, natural diamond, synthetic diamond, vapor deposited diamond, silicon bonded diamond, cobalt bonded diamond, thermally stable diamond, infiltrated diamond, layered diamond, cubic boron nitride, diamond impregnated matrix, diamond impregnated carbide, metal catalyzed diamond, or combinations thereof. The hardened tip can include other materials and/or compositions having a hardness similar to diamond. The hardened tip preferably comprises a material having a hardness greater than the hardness of the material of the cutter bit holding insert such that the insert wears earlier than the hardened tip. A cutter bit with such a hardened tip can be directly engaged with a base portion by a screw-threaded or other similar connection. 
     The above advantages, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an enlarged, partial cross-sectional view of a base portion, a wear insert having a cutter bit, and a retainer. 
         FIG. 2  is an enlarged, partial cross-sectional view of the base portion of  FIG. 1  depicting the exterior of the wear insert and the retainer. 
         FIG. 3  is a side view of a wear insert having a cutter bit longitudinally isolated from a retainer, depicted without a base portion. 
         FIG. 4  is a side view of an alternative wear insert longitudinally isolated from an upper and a lower retainer. 
         FIG. 5  is a perspective view depicting an embodiment of a base portion, an insert, a cutter bit, and a retainer. 
       FIG.  5 ′ is a side view depicting the engagement of the cutter bit and the insert of  FIG. 5 . 
         FIG. 6  is a perspective view depicting another embodiment of a cutter bit and a retainer. 
         FIG. 7  is a side view depicting another embodiment of a cutter bit and a retainer. 
         FIG. 8  is a side view depicting another embodiment of a cutter bit that can be engaged with a retainer or directly with a base. 
         FIG. 9  is a side view of another embodiment of a cutter bit shown engaged with a base and retainer shown in section. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to all the Figures where reference numerals are generally used to identify like components,  FIG. 1  illustrates one embodiment of an apparatus  10  for use on a portion of a cylindrical surface of a milling or mining drum, adapted to be rotated in a cutting direction R about a cylindrical axis defined by the drum. Optionally, the apparatus  10  can be used on flighting that is attached to the portion of the cylindrical surface portion of the drum. A base portion  20  can be mounted to the surface of the drum or to the flighting, for instance by bolting or welding. The base portion  20  can include at a cutter bit  22  at the radially outward extremity of the base portion  20 . The cutter bit  22  can be cylindrically shaped with a conical tip, which typically a hardened portion, which is directed forward in the direction R. The hardened tip can include carbide or other compositions described below. Cutter bits  22  can forcibly contact a surface to be mined or milled and, in a known manner, mine, mill, or reclaim a controlled portion of such surface. As a result, this can leave such surface substantially planar with a slightly roughened surface texture. 
     The base portion  20  includes a body having at least a mounting surface  24 . The base portion  20  can be mounted to a radially outermost portion of the drum or flighting sections, so that the mounting surface  24  is adjacent to the radially outermost portion. Side welds can attach together adjacent base portions  20  and, in addition, help prevent loosened roadway material from moving between adjacent base portions. The body of the base portion  20  can also include a lower surface  26  and an upper surface  28 . The lower and upper surfaces  26 ,  28  can be generally parallel with respect to one another. 
     The base portion  20  can define an opening  30  that is aligned with a longitudinal axis Z running therethrough. The opening  30  can be adapted to receive a wear insert  40  for retaining the cutter bit  22 . The opening  30  of the base portion  20  includes a lower end  31  and an upper end  32  that may have a first seat  34 , preferably a conical seat, located at the upper end  32  of the base portion opening  30 . The base portion opening  30  can also include a second seat  38 , preferably a conical seat, proximate the lower end  31  of the base portion opening  30 . The first and/or second seat  34 ,  38  can be tapered at an angle A in the range between about 5 to about 70 degrees, preferably about 20-50 degrees, relative to the longitudinal axis Z, as shown in  FIG. 2 . Preferably, the angles A of tapering for the first and second seats  34 ,  38  are substantially similar. Between the upper and lower ends  31 ,  32 , or optionally the first and second seats  34 ,  38 , is a middle portion  36  that can define a substantial portion of the base portion opening  30 . 
     Referring to  FIGS. 1-3 , the wear insert  40  can include a nut-like gripping surface  42  proximate the upper surface  28  of the base portion  20  and a flange  44  extending from the nut-like gripping surface  42  to a middle portion  47 . The flange  44  can frictionally engage with the base portion first seat  34 . Preferably, the flange  44  is a conical shoulder having the same tapering rate as the angle A of the first seat  34 . The wear insert  40  can have a first end  46  and a second end  48 . The first end  46  is positioned at an upper surface  49  of the wear insert  40  away from the mounting surface  24 , and the second end  48  is positioned at a lower surface  51  of the wear insert  40  proximate the mounting surface  24 . The second end  48  can project beyond the lower surface  26  of the base portion  20 . Between the first and second ends  46 ,  48  is the middle portion  47  that preferably slidably engages with at least a substantial portion of the middle portion  36  of the opening  30  of the base portion  20 . The wear insert  40  can also include threads  52  extending from the middle portion  47  to the second end  48  of the wear insert  40 . For example,  FIG. 3  illustrates the wear insert  40  having external threads. Alternatively, the wear insert  40  can have internal threads. 
     The wear insert  40  can slidably engage with the opening  30  of the base portion  20 , until the flange  44  of the wear insert  40  is disposed in wedged frictional contact against the first seat  34  of the base portion  20 . A retainer  60  can be provided to securably engage the wear insert  40  within the base portion opening  30 . As a result, the wear insert  40  can be secured to the base portion  20 , which can keep the threads  52  of the wear insert  40  from being under shock load of the cutting operation. The nut-like gripping surface  42  of the wear insert  40  can allow for easy access for removal of the wear insert  40 . The wear insert  40  can be formed of material that is not welded and can therefore maintain hardness. 
     In  FIGS. 1 and 2 , the wear insert  40  includes an interior bore  50 . The interior bore  50  can be sized for receiving at least one cutter bit  22 . As illustrated in  FIG. 1 , the interior bore  50  can have a first end  54  positioned proximate the first end  46  of the wear insert  40  and a second end  56  proximate the second end  48  of the wear insert  40 . The first end  54  of the interior bore  50  is for removably receiving the cutter bit  22 . 
     An expandable cylindrical sleeve  70  can also be provided to frictionally engage the wear insert  40 , thereby preventing the cutter bit  22  from translating within the interior bore  50  of the wear insert  40 . The expandable sleeve  70  is attached around a shank portion of the cutter bit  22 , with the expandable sleeve  70  being normally in an expanded state. The cutter bit  22  with the expandable sleeve  70  can be forcibly inserted into the interior bore  50 , which causes the expandable sleeve  70  to move between the expanded state and a compressed state to frictionally engage the cutter bit  22  and the surface of the interior bore  50 . The combined cross-sectional area of the shank of the cutter bit  22  and the expandable sleeve  70  should be slightly less than the cross-sectional area of the interior bore  50  to ensure securable engagement within the interior bore  50 . The threads  52  of the wear insert  40  and the interior bore  50  of wear insert can be disposed substantially coaxially. 
     In some embodiments, the interior bore  50  can also include a key or other protrusion  71  to engage with the expandable sleeve and prevent rotation therein. For example, in the partial cut away in  FIG. 1 , the protrusion  71  is a raised portion extending longitudinally through the interior bore, although the protrusion can be a series of protrusion and/or can be disposed within various locations within the interior bore. The protrusion  71  can engage a nipple, raised portion, or longitudinal edge of the expandable sleeve  70  to further inhibit rotation of the sleeve  70  relative to the bore  50 . Rotation of the sleeve  70  is caused by the rotation of the cutter bit  22  during operation. Rotatable movement of the sleeve  70  within the interior bore  50  may cause undesirable wear and tear to the bore of the wear insert  40 . 
     The interior bore  50  can also include an entry opening  53 . The entry opening  53  preferably is a conical opening having a first end proximate the first end  54  of the interior bore  50 , which can engage a flange of the cutter bit  22 . The cross-sectional area of the interior bore  50  can be greater than the cross-sectional area of a second end positioned lower than the first end of the entry opening  53 . The interior bore  50  preferably has a circular cross-sectional area. 
     In some embodiments, the interior bore  50  may have an internal flange  55  with a reduced cross-sectional area as compared to a substantial portion of the interior bore  50 .  FIG. 1  illustrates the internal flange  55  having a cross-sectional area slightly less than the cross-sectional area of the cutter bit  22  in order to reduce the likelihood of abrasive dust entering into the interior bore  50  and to further secure the expandable sleeve  70  within the interior bore  50 . Although the lower portion of the edge of the internal flange  55  is shown in  FIG. 1  to be a chamfered edge to facilitate the removal of the expandable sleeve  70 , the lower portion of the internal flange  55  can be square or perpendicular. The chamfered edge can urge the expandable sleeve  70  to radially compress to the compressed state, i.e., a cross-sectional area that is small enough to permit withdrawal. The angle of the chamfered edge can be about 30 degrees to about 60 degrees; however, it can be appreciated by one skilled in the art that the angle can be any degree suitable to retain the expandable sleeve  70  in one aspect, and to urge the expandable sleeve  70  to the compressed state in another aspect. In other embodiments, the cross-sectional area of the interior bore  50  can be substantially the same throughout, and a step ring can be attached, preferably by brazing, welding or the like, at a region near the first end  54  of the interior bore  50 . The step ring has an outer edge with a cross-sectional area substantially similar to the cross-sectional area of the interior bore  50  and an inner edge with a cross-sectional area that is less than the cross-sectional area of the outer edge. The material of the step ring can be made of metal known in the art, and preferably, hardened steel or carbide. The step ring can perform the same function, and can also have the chamfered edge, similar to the internal flange  55  described above. 
     As mentioned previously, the retainer  60  can be provided to securably engage the wear insert  40  within the base portion opening  30 . Referring to  FIG. 3 , the retainer  60  can include threads  62  to threadably engage the threads  52  of the wear insert  40 . Although  FIG. 3  illustrates the retainer  60  having internal threads, the retainer  60  optionally can have external threads. The retainer  60  can also include a gripping surface  64  to rotatably engage and disengage the retainer threads  62  from the threads  52  of the wear insert  40 . The retainer  60  can also include a flange  66  that can be frictionally engaged with the second seat  38 , as shown in  FIG. 2 . The retainer flange  66  can be angled at various angles, including the range between about 10 to about 70 degrees, preferably about 20-50 degrees, relative to the longitudinal axis Z. Preferably, the retainer flange  66  is a conical shoulder. The tapering angle of the wear insert flange  44  and the retainer flange  66  can be substantially similar as the tapering rate of the first and second seats  34 ,  38 , respectively. At least a portion of the retainer  60  can be accessible from the lower surface  26  of the base portion  20 , where a tool can rotatably engage and disengage the retainer threads  62  from the wear insert threads  52 . The retainer  60  can be a specifically machined part designed according to specification or can be a conventional fastener, preferably a hexagonal nut fastener that is modified with the retainer flange  66 . As shown in  FIGS. 1 and 2 , the retainer  60  is preferably entirely within the base opening  30  in order for portions of the base  20  to protect the retainer  60  from wear and tear and to reduce the risk of dust or debris from entering the retainer  60 . There can be enough gap or separation between the retainer  60  and the base  20  to permit a suitable tool to engage the retainer  60 . 
     Also provided is a method of replacing a wear insert  40  and/or cutter bit  22 . Damage to the cutter bit  22  and/or the wear insert  40 , instead of the base portion  20 , is more desirable because the cutter bit  22  and/or the wear insert  40  are less expensive to replace. The cutter bit  22  and/or wear insert  40  can become damaged by wear and tear due to the abrasive forces being transmitted to the wear insert  40  via the cutter bit  22 . Oftentimes, the forces are unevenly distributed between the cutter bits  22  and wear insert  40 , which causes the cutter bit  22  to vibrate and otherwise move and rotate within the wear insert interior bore  50 . Particularly, in the presence of abrasive dust from the roadway surface reclaiming operation, the vibration and movement of the cutter bit  22  act to such an extent that the cutter bit  22  is no longer retained. Even worse, the forces occasionally become constant enough to fatigue or large enough damage the cutter bits  22  and/or the wear insert  40  causing the machine to be stopped for considerable lengths of time, such as 2-40 hours, for repair and replacement of the base portions  20 , cutter bits  22 , wear inserts  40 , or all. When only the cutter bit  22  needs replacing, the cutter bit  22  with the expandable sleeve  70  can be punched out of the interior bore  50  of the wear insert  40  by inserting a first tool into the second end  56  of the interior bore  50  of the wear insert  40  to contact the lower end of the cutter bit  22 . A second tool can then hammer the inserted first tool to punch out forcibly the cutter bit  22  with the expandable sleeve  70  from the first end  54  of the interior bore  50  of the wear insert  40 . A replacement cutter bit with the expandable sleeve can then be inserted into the first end  54  or entry opening  53  of the interior bore  50  of the wear insert  40  by hammering the top end of the replacement cutter bit to punch in the replacement cutter bit within the interior bore  50  of the wear insert  40 . 
     The wear insert  40  can be replaced with the following steps. The wear insert  40  can be damaged by wear and tear of the interior bore  50  due to abrasive dust or a loosened cutter bit, or by wear and tear of the threads  52  and/or the nut-like gripping surface  42 .  FIG. 2  illustrates the apparatus  10  having the base portion  20 , a wear insert  40 , depicted with the cutter bit  22  before being replaced. The cutter bit  22  with the expandable sleeve  70  may be punched out from engagement with the interior bore  50  of the wear insert  40  before removing the wear insert  40 . One step can include engaging an appropriate tool (not shown), such as a socket, with the retainer  60  from the lower surface  26  of the base portion  20 . Once the appropriate tool is securably engaged with the gripping surface  64  of the retainer  60 , the appropriate tool can be rotated with sufficient force in an appropriate direction to remove the retainer  60 , as illustrated in  FIG. 3 . If rotation of the appropriate tool causes the rotation of the wear insert  40  in the same direction, another tool (not shown), such as a socket, can be securably engaged with the nut-like gripping surface  42  of the wear insert  40  to prevent the wear insert  40  from rotating. Once the tool is engaged with the wear insert  40 , the threads  52  of the wear insert  40  can be disengaged from the threads  62  of the retainer  60 . The wear insert  40  can then be removed from the base portion  20 . 
     Accordingly, the wear insert  40  is removed and a replacement wear insert can be installed with the aforementioned steps in reverse order. The wear insert  40  can slidably engage with the opening  30  of the base portion  20 , until the flange  44  of the wear insert  40  is disposed in wedged frictional contact against the first seat  34  of the base portion  20 . The retainer  60  can be then inserted around the threads  52  of the wear insert  40 . An appropriate tool can be securably engaged with the retainer  60  to rotate the retainer  60  with sufficient force in an appropriate direction to tighten the retainer  60 . If rotation of the appropriate tool causes the rotation of the wear insert  40  in the same direction, another tool can be securably engaged with the nut-like gripping surface  42  of the wear insert  40  to prevent the wear insert  40  from rotating. Consequently, the wear insert  40  can be secured to the base portion  20 , which can keep the threads  52  of the wear insert  40  from being under shock load of the cutting operation. The replacement cutter bit can be forcibly inserted or punched into the interior bore  50  of the wear insert  40  after the wear insert  40  is securably engaged with the base portion  20 . 
     In another embodiment of the wear insert  140 , two retainers, an upper retainer  142  and a lower retainer  160 , may be removably attached to a portion of a shank  144  of the wear insert  140 , as shown in  FIG. 4 . The wear insert  140  is similar to the wear insert  40  described herein except for the following. The shank  144  of the wear insert  140  includes a threaded portion at the upper end  146 , in addition to the lower end  148 . The upper retainer  142  can have a nut-like configuration including a gripping surface  150  on the exterior and internal threads  152 . The internal threads  152  can threadably engage with the threads  154  of the upper end  146  of the shank  144 . Optionally, the upper retainer  142  can have a portion extending from the gripping surface  150  that has external threads, which can be threadably engaged with internal threads of the upper end  146  of the shank  144 . The upper retainer  142  also includes a flange  156  extending from the gripping surface  150  that can frictionally engage with the first seat  34  of the base portion  20 . The lower retainer  160  is similar to the retainer  60  as described herein. The lower retainer  160  has threads  162  that can engage with the threads  158  at the lower end  148  of the shank  144 . The threads  158 ,  154  can be machined in the same or opposite direction. A cutter bit can be forcibly inserted in or removed from the wear insert  140  without removing the upper retainer  142  by punching in or out the cutter bit into the interior bore  159  with an appropriate tool. If the upper retainer  142  is removed, after a replacement cutter bit is inserted into the interior bore  159  of the wear insert  140 , the upper retainer  142  can be reattached to the shank  144  of the wear insert  140 . 
       FIG. 5  illustrates another embodiment of the apparatus  210  for use on a portion of a cylindrical surface of a milling or mining drum. The cutter bit  212  includes a hardened tip  214 . The hardened tip  214  may include a diamond working end attached to a carbide substrate, the diamond working end having a pointed geometry. The diamond working end may comprise diamond, polycrystalline diamond, natural diamond, synthetic diamond, vapor deposited diamond, silicon bonded diamond, cobalt bonded diamond, thermally stable diamond, infiltrated diamond, layered diamond, cubic boron nitride, diamond impregnated matrix, diamond impregnated carbide, metal catalyzed diamond, or combinations thereof. The hardened tip  214  may include other materials and/or compositions having a hardness similar to diamond. The hardened tip  214  preferably comprises a material having a hardness greater than the hardness of the material of the insert  230 , such that the insert wears earlier than the hardened tip. 
     The shank portion  216  of the cutter bit includes various regions of different diameters. For example, the shank portion  216  can include a tip region  218  having a diameter and a base region  220  having a diameter less than the tip region diameter and a transition  222  therebetween. The tip region  218  is attached to the hardened tip  214 . The transition  222  is tapered at a small angle between 2-10 degrees and is preferably a Morris taper. The base region  220  of the shank portion is sized to slide through the opening  224  of the base portion  226 . The base region  220  can also include a threaded portion  228 . 
     The insert  230  includes a bore  232  having a first region  233  dimensioned to engage with the transition  222  of the shank portion  216  of the cutter bit  210 . The engagement between the first region  233  of the insert bore and the transition  222  of the shank portion of the cutter bit provides substantially non-rotatable movement therebetween, and “locks” the two members together. A locking engagement between the first region  233  of the insert bore and the transition  222  of the shank portion of the cutter bit can also be provided by threads or splines on both surfaces. The bore  232  can include a second region with a diameter sized to slidably receive the base region  220  of the shank portion  216  of the cutter bit  210 . The insert  230  can also include tapered regions on the exterior. The exterior portion  234  facing the tip region  218  can be tapered, or conically or spherically shaped, in order to better deflect debris when in operation. The exterior portion  236  facing away from the tip region can be tapered, or conically or spherically shaped, in order to better engage with the base portion  226 . The engagement between exterior portion  236  of the insert  230  and a first seat  242  of the base portion opening  224  provides substantially non-rotatable movement therebetween, and “locks” the two members together. The insert  230  can be made of softer material than the hardened tip  214  of the cutter bit  210  in order to wear earlier than the cutter bit  210 . The insert  230  can function as a deflector of debris away from the base portion and frictional inducing member to retain the cutter bit and to be retained by the base portion. 
     The base portion  226  includes a body having a mounting surface  237  and a lower surface  238  and an upper surface  240 . The base portion  226  can be mounted and attached, as described above, to a radially outermost portion of the drum or flighting sections such that the mounting surface  237  is adjacent to the radially outermost portion. The base portion opening  224  is aligned with a longitudinal axis Z running therethrough. The opening  224  can be adapted to receive the insert  230  and a portion of the cutter bit  212 . A first seat  242 , preferably a conical seat or spherical seat, may be located at the upper end  240  of the base portion opening  224 . A second seat (not shown), preferably a conical seat or spherical seat, is proximate the lower end of the base portion opening. The first seat and/or second seat can be tapered at an angle in the range between about 5 to about 70 degrees, preferably about 20-50 degrees, relative to the longitudinal axis Z. Preferably, the angle of tapering for the first and second seats is substantially similar. Between the upper and lower ends, or optionally the first and second seats, is a middle portion  244  that can define a substantial portion of the base portion opening  224 . The middle portion  244  of the opening  224  is sized to slidably receive a portion of the shank portion  216  of the cutter bit  212 . 
     The retainer  246  can threadably engage with the threaded portion  238  of the cutter bit  212  after being inserted through the base portion opening  224 . The retainer  246  can include a threaded portion  248  dimensioned to threadably engage the threaded portion  228  of the cutter bit  212 . The retainer  246  can also include a gripping surface  250  to rotatably engage and disengage the retainer threaded portion  248  from the threaded portion  228  of the cutter bit  212 . The retainer  246  can also include a flange  252  that can be frictionally engaged with the second seat of the base portion opening  224 . The retainer flange  252  can be angled at various angles, including the range between about 10 to about 70 degrees, preferably about 20-50 degrees, relative to the longitudinal axis Z. Preferably, the retainer flange  252  is a conical shoulder. At least a portion of the retainer  246  can be accessible from the lower surface  238  of the base portion  226  such that a tool can rotatably engage and disengage the retainer threaded portion  248  from the cutter bit threaded portion  228 . In some embodiments, the retainer  246  is a specifically machined part designed according to specification or can be a conventional fastener, preferably a hexagonal nut fastener that is modified with the retainer flange  252 . In some embodiments, the retainer  246  is entirely within the base portion opening  224  in order for portions of the base portion  226  to protect the retainer  246  from wear and tear and to reduce the risk of dust or debris from entering the retainer  246 , similar to what is illustrated in  FIG. 2 . There can be enough gap or separation between the retainer  246  and the base portion  226  to permit a suitable tool such as a socket or wrench to engage the retainer. 
     A method of assembling the embodiment of the apparatus  210  is also included. With reference to  FIG. 5 , the shank portion  216  of the cutter bit  212  can be inserted through the bore  232  of the insert  230  and axially moved therethrough such that the transition  222  of the cutter bit  212  and the insert  230  engage. FIG.  5 ′ is a side view depicting the engagement of the cutter bit  212  and the insert  230 . With securable engagement between the insert  230  and the cutter bit  212 , the shank portion  216  can be inserted through the base portion opening  232  such that the threaded portion  228  of the cutter bit  212  is accessible from the lower end. With the exterior portion  236  of the insert  230  securably engaged with the first seat  242  of the base portion opening  224 , the retainer  246  can then be threadably engaged with the cutter bit  212  and suitably tightened. With the apparatus assembled, the cutter bit  212  thereby is prevented from rotating during operation. This prevention is due primarily to the surface area contact and frictional contact between the cutter bit  212  and the insert  230  and the insert  230  and the base portion  224 . Lack of rotation can be acceptable due to the hardness of the hardened tip and its ability to absorb the operational forces. To disassemble, the aforementioned steps can be reversed. Disassembling may be required periodically in order to promote wearing evenly around the hardened tip. Accordingly, the cutter bit  212  and/or the insert  230  can be manually rotated in order to distribute the wear and tear of the hardened tip to other regions. In addition, the insert  230  may wear before the cutter bit  212  and thus may be replaced with a new insert. 
       FIG. 6  illustrates another embodiment of the apparatus  310  which is substantially similar to the apparatus  210  except with the differences described below. The tip region  318  includes the hardened tip  314  that is attached to a conical section  317  extending axially therefrom and a flange  319 . The shank portion  316  of the cutter bit  312  can have a polygonal shaped portion  322  between the flange  319  of the tip region  318  and the base region  320 . The polygonal shaped portion  322  can have a larger cross-sectional area than the cross-sectional area of the base region  320 . A portion of the insert bore  332  of the insert  330  is shaped to be substantially identical to the polygonal shaped portion  322  of the cutter bit  312  in order to be received when inserted through the bore. The number of sides of the polygonal shaped portion  322  can dictate the degree of rotation of the cutter bit. For example, a hexagon (six sides) is shown in both the insert bore  332  and the polygonal shape portion  322  of the cutter bit  312 . Thus, the cutter bit  312  can be rotated in 60-degree (360 degrees/6 sides) increments. A portion  334  of the exterior surface of the insert  330  may also be polygonally shaped, which is shown in  FIG. 6  as a hexagon. A portion of the exterior surface of the insert facing away from the tip region  318  can be tapered, or conically or spherically shaped, in order to better engage with the base portion opening  224 . 
       FIG. 7  illustrates another embodiment of the apparatus  410  which is substantially similar to the apparatuses  210 ,  310  except with the differences described below. The tip region  418  includes the hardened tip  414  that is attached to a conical section  417  extending axially therefrom and a flange  419 . The transition  422  of the shank portion  416  of the cutter bit  412  can be tapered between the flange  419  of the tip region  418  and the base region  420  at an angle larger than the Morris taper. For example, the transition  422  can be tapered at an angle in the range between about 10 to about 70 degrees, preferably about 20-50 degrees, relative to the longitudinal axis Z. Threads  424  can be provided at a lower end  426  of the shank portion  416 . The bore  432  of the insert  430  can have two regions (not shown in the figures) shaped to be substantially identical to shank portion  416  of the cutter bit  412  in order for the cutter bit to be received in the bore when inserted therethrough. The first region of the bore  432  is sized to receive and engage with the transition  422  of the cutter bit  412 , having a taper substantially identical to the taper of the transition  422 . The second region of the bore  432  is sized to receive the base region  420  of the cutter bit  412 . A portion  434  of the exterior surface of the insert  430  facing the tip region  418  may be polygonally shaped, with  FIG. 7  depicting one embodiment as a hexagon. A portion  436  of the exterior surface of the insert  430  facing away from the tip region  418  can be tapered, or conically or spherically shaped, in order to better engage with the base portion opening  224 . In other examples, the insert  430  can be omitted, and the transition  422  of the cutter bit  412  can engage with the base portion opening  224 . A lower retainer  460  can also be provided having threads that can engage with the threads  424  at the lower end  426  of the shank portion  416 . The threads  424  on the shank portion  416  and the threads in the lower retainer can be machined in either direction to provide right or left locking engagement. The lower retainer  460  can include a flange  466  that can be frictionally engaged with the second seat  38 , as shown in  FIG. 2 . The retainer flange  466  can be angled at various angles, including the range between about 10 to about 70 degrees, preferably about 20-50 degrees, relative to the longitudinal axis Z. Preferably, the retainer flange  466  is a conical shoulder. The threads  424  on the shank portion  416  can alternatively engage a threaded interior bore  50  of a base  20  as shown, for example, in  FIG. 9 . 
       FIG. 8  shows a side view depicting another cutter bit  512  that includes a shank portion  516  having threads  524  on a base portion  521  that can engage a suitable retainer as shown, for example, in  FIG. 5 , or can engage directly with a base as shown, for example, in  FIG. 9 . The cutter bit  512  can include a tip region  518  supporting a hardened tip  514 . The tip region  518  is attached to an outwardly tapered conical region  517  leading to a flange portion  519 . The flange portion  519  can include a nut-like configured gripping surface  522 . Like the embodiment shown in  FIG. 5 , the hardened tip  514  can include a diamond working end attached to a carbide substrate, the diamond working end having a pointed geometry. The diamond working end can comprise diamond, polycrystalline diamond, natural diamond, synthetic diamond, vapor deposited diamond, silicon bonded diamond, cobalt bonded diamond, thermally stable diamond, infiltrated diamond, layered diamond, cubic boron nitride, diamond impregnated matrix, diamond impregnated carbide, metal catalyzed diamond, or combinations thereof. The hardened tip  514  can also include other materials and/or compositions having a hardness similar to diamond. 
       FIG. 9  shows a side view of another embodiment of a cutter bit  612  shown engaged with a base  620  and retainer  660  shown in section. The cutter bit  612  is similar in construction to the cutter bit  512  shown in  FIG. 8 . The cutter bit  612  includes threads  624  on a base portion  621  that can engage directly with the base  620 . The cutter bit  612  can include a tip region  618  supporting a hardened tip  614 . The tip region  618  is attached to an outwardly tapered conical region  617  leading to a flange portion  619 . The flange portion  619  can include a nut-like configured gripping surface  622 . Like the embodiments shown in  FIG. 5  and  FIG. 8 , the hardened tip  614  can include a diamond working end attached to a carbide substrate, the diamond working end having a pointed geometry. A retainer  660  can be internally threaded into a lower end  630  of the threaded opening  632  of the base  620 . The retainer  660  can have a working engagement surface  662  at a lower end  664  of the retainer  660 , which can be accessed through an opening  634  in the base. The retainer  660  can have an outside thread  636  that is smaller than and threaded opposite the opposite direction to the threads  624  on the cutter bit  612 . After insertion of the cutter bit  612  into the base  620 , the retainer  660  can be advanced into locking engagement with the lower end of the cutter bit  612 . 
     In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described.