Abstract:
A sleeve utilizing two methods of retention—a friction fit and a rear retention feature—is disclosed. The sleeve includes a circumferentially compressible portion that provides a friction fit when inserted into a bore and includes a projected portion around an end circumference that is used to mate with the rear of a tool block and urges the sleeve (and the tool) rearward. The disclosure also relates to a tool and block assembly, a method of retaining a tool in a holder and a mining machine incorporating the sleeve.

Description:
RELATED APPLICATION DATA 
       [0001]    This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 60/935,851, filed Sep. 4, 2007, entitled “Hybrid Retainer Sleeve For Tool Inserted into Block”, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a sleeve for retaining a tool in a block. More particularly, the present disclosure relates to a retainer sleeve that fits about the shank of a tool and is inserted into a bore of a block to form an assembly. The retainer sleeve incorporates both a friction fit and a rear retaining feature. 
       BACKGROUND 
       [0003]    In the discussion of the background that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art. 
         [0004]    Mining and construction machines are being designed with progressively faster cutter drum and chain speeds. These advancements are making it more difficult to retain tools in their respective holders, such as a tool block or a bore of a rotating drum. For this reason, friction sleeve retainers are becoming less effective in retaining tools. Many industries are starting to progress towards rear retention to hold tools in holders. 
         [0005]    Rear retainers are typically used in applications where the user needs maximum retention. These retainers are separate, loose parts that are inserted in a retaining feature, such as a groove, on the portion of the tool shank that projects beyond the rear of the tool block. 
         [0006]    Rear retainers have certain limitations. Rear retainers can be difficult to assemble and remove due to limited access behind the holder. In order to assemble a typical external retainer onto a tool, a certain amount of clearance is required between the rear of the holder and the groove in the tool shank. This clearance can allow unnecessary freedom of movement between the tool and holder, causing an unwarranted amount of slapping between the tool shoulder and face of the holder. This slapping can cause excessive wear in the bore and on the face of the holder, reducing the lifetime of both parts. 
         [0007]    Certain retainers require special tools (for example, snap rings require special pliers) while others require excessive force (for example, cut washers) during installation and removal. Due to the elastic memory of these retainers, during removal many retainers are prone to “pop” off in any given direction. This can make the removal of these “projectile” retainers dangerous on the job site as well as cumbersome to use if one loses the retainer and needs to find a replacement. 
       SUMMARY 
       [0008]    An improved sleeve utilizing two methods of retention—a friction fit as well as a rear retainer—has advantageous performance characteristics as well as improved ease of use. 
         [0009]    An exemplary embodiment of a sleeve for retaining a tool in a block comprises a hollow cylindrical body having a first end, a second end and a connecting surface therebetween arranged axially, a first axially extending slit in the connecting surface extending from the first end to the second end, at least one second axially extending slit in the connecting surface extending from the second end to a termination point between the first end and the second end, and a projected portion offset from the second end, wherein the sleeve at the projected portion projects radially outward with a radius larger than a radius of an outer diameter of the hollow cylindrical body, and wherein the termination point is axially closer to the first end than the projected portion. 
         [0010]    Another exemplary embodiment of a sleeve for retaining a tool in a block comprises a hollow cylindrical body having a first end, a second end and a connecting surface therebetween arranged axially, a plurality of sections arranged circumferentially at the second end, and a projected portion offset from the second end, wherein the hollow cylindrical body is circumferentially compressible, and wherein each of the plurality of sections is independently radially compressible. 
         [0011]    An exemplary embodiment of a mining machine comprises a rotatable member, and one or more tools mounted on the rotatable member, wherein the one or more tools are mounted with a sleeve including a hollow cylindrical body having a first end, a second end and a connecting surface therebetween arranged axially, a plurality of sections arranged circumferentially at the second end; and a projected portion offset from the second end, wherein the hollow cylindrical body is circumferentially compressible, and wherein each of the plurality of sections is independently radially compressible. 
         [0012]    An exemplary embodiment of a tool and block assembly comprises a block including a body having a bore extending axially from a first side to a second side, a tool including a body having a head and a shank, and a sleeve positioned about the shank, wherein the sleeve includes a hollow cylindrical body having a first end, a second end and a connecting surface therebetween arranged axially, a plurality of sections arranged circumferentially at the second end, and a projected portion offset from the second end, wherein at least a portion of the connecting surface has a friction fit with the bore, wherein the projected portion contacts the block to urge the sleeve rearward, and wherein the tool is rotatable. 
         [0013]    An exemplary embodiment of a method of mounting a rotatable tool in a bore of a holder comprises securing the tool in the bore with a sleeve that provides both a friction fit and a rear retention feature. 
         [0014]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0015]    The following detailed description can be read in connection with the accompanying drawings in which like numerals designate like elements and in which: 
           [0016]      FIG. 1  is a cross-sectional view of an exemplary embodiment of a tool assembly including a tool, a hybrid retainer and a holder. 
           [0017]      FIG. 2  is an isometric view of an exemplary embodiment of a hybrid retainer sleeve. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    An exemplary embodiment of a tool in a block is schematically illustrated in  FIG. 1 . The tool  2  includes a body  4  having a head  6  and a shank  8 . The head  6  includes a front surface  10  and a side surface  12 . The side surface  12  extends axially rearwardly from the front surface  10  toward a shoulder  14 . The side surface  12  can be of various forms from being oriented substantially perpendicular to a central axis  16  of the body  4  to being oriented at an angle α to the central axis  16  (the angle α opening rearward), and combinations thereof and the form of the side surface  12  can be planar, concave, convex or combinations thereof. The side surface shown in  FIG. 1  is an example of a concave form. A cutting tip  20  is attached to the front surface  10  of the head  6 . The cuffing tip  20  is made from a hard material. A suitable hard material for the cutting tip  20  is cemented carbide. An exemplary composition of the cemented carbide includes 6-12 wt. % Co and balance WC. 
         [0019]    The block  30  can have any suitable shape, generally adapted to the mining machine on which it is mounted and adapted to the tool which it supports. An exemplary embodiment of a block  30  includes a body  32  having a bore  34  extending axially from a first side  36  to a second side  38 . The bore  34  can be smooth along its inner diameter, albeit the bore  34  can be stepped, i.e., have variation in the inner diameter along its length, or the bore  34  can include an internal groove. An example of a stepped bore is shown in  FIG. 1  with a first portion  40  and a second portion  42 . Other stepped bore arrangements are disclosed in U.S. Pat. Nos. 7,234,782 and 5,302,005, the entire contents of which are incorporated herein by reference. An example of a bore with an internal groove is disclosed in U.S. Pat. No. 4,484,783, the entire content of which is incorporated herein by reference. The block  30  has a mounting surface  44  at a third side. The mounting surface  44  is adapted for mounting to a rotatable drum of a mining machine or other rotatable member of a construction machine, tunneling machining or trenching machine, such as Sandvik model MT720 tunneling machine or Voest-Alpine&#39;s Aline Bolter Miner ABM 25. 
         [0020]    A sleeve  50  is arranged about at least a portion of the shank  8  inserted into the bore  34  of the block  30 . An exemplary embodiment of a sleeve is shown in  FIG. 2 . The sleeve  50  includes a hollow cylindrical body  52  having a first end  54 , a second end  56  and a connecting surface  58  therebetween arranged axially. The cylindrical body  52  can have any suitable form, such as an elliptical cylindrical body or a right circular cylindrical body. In an exemplary embodiment, the sleeve  50  is formed from a spring steel. 
         [0021]    The sleeve  50  includes a plurality of slits formed by the removal of at least some material from the hollow cylindrical body  52 . Each of the slits interrupts the generally continuous surface of the hollow cylindrical body  52 . 
         [0022]    A first axially extending slit  60  in the connecting surface  58  extends from the first end  54  to the second end  56 . The first axially extending slit  60  allows circumferential compression of the sleeve  50  from a first circumference at a first radial distance to a second circumference at a second radial distance. At the first circumference, the edges  62  of the first axially extending slit  60  are separated by a distance (D 1 ); at the second smaller circumference, the edges  62  of the first axially extending slit  60  are separated by a distance (D 2 ). The distance D 1  is greater than the distance D 2 . The distance D 2  can be zero, i.e., the edges contact each other, along at least a portion of the axial length of the edges  62 . During circumferential compression, the general cylindrical form of the sleeve  50  holds, but the circumference is reduced. Similarly, the first axially extending slit  60  allows circumferential expansion of the sleeve  50  from the first circumference at the first radial distance to a larger third circumference at a third radial distance, where the separation distance of the edges  62  is increased along at least a portion of the axial length of the edges  62 . 
         [0023]    At least one second axially extending slit  70  in the connecting surface  58  extends from the second end  56  to a termination point  72  between the first end  54  and the second end  56 . The at least one second axially extending slit  70  divides the second end  56  into a plurality of sections  74  arranged circumferentially at the second end  56 . The at least one second axially extending slit  70  allows radial compression of each of the plurality of sections  74  from a first radial distance to a second radial distance. The radial compression for any one section  74  can be independent from any other section  74 . At the first radial distance, the edges  76  of the at least one second axially extending slit  70  associated with one section  74  are separated by a distance (d 1 ) from the edges of adjacent sections  74 ; at the second radial distance, at least a portion of the edges  76  of the at least one second axially extending slit  70  associated with the one section  74  are separated by a distance (d 2 ) from the edges of adjacent sections  74 . The distance d 1  is greater than the distance d 2 . The distance d 2  can be zero, i.e., the edges contact each other, along at least a portion of the axial length of the edges  76 . Typically, the portion where the edges contact will be the portion closest to the second end  56 . Similarly, one or more of the sections  74  can be moved radially outward from a first radial distance to a larger third radial distance, where the separation distance of the edges  76  is increased along at least a portion of the axial length of the edges  76 . During the compression or expansion, the radial distance of any one of the sections  74  varies, either alone of in conjunction with other sections  74 , depending on the forces applied to the sections  74 . Therefore, one section  74  can have a reduced radial distance while an adjacent section can have an unchanged or increased radial distance. When all of the plurality of sections  74  move at the same time in the same direction, i.e., radially inward or radially outward, the sections effectively move to reduce or increase the circumference in that portion of the sleeve  50 . 
         [0024]    The sleeve  50  includes a projected portion  80 . The sleeve  50  at the projected portion  80  projects radially outward with a radius larger than a radius of an outer diameter of the hollow cylindrical body  58 . The projected portion  80  is offset from the second end  56 . For example, the projected portion  80  can be in the sections  74 , with the termination point  72  of the second axially extending slit  70  axially closer to the first end  54  than is the projected portion  80 . The projected portion  80  can have any suitable geometric form. In an exemplary embodiment and as shown in  FIGS. 1 and 2 , the projected portion is hemispherical. In other exemplary embodiments, the geometric form can be a circumferentially arranged series of bumps, an angled surface or any other protrusion, as long as the radius of the sleeve  50  at the projected portion  80  is the larger than the radius on the sleeve  50  that would contact the inner surface of the bore when assembled. 
         [0025]    As shown in  FIG. 1 , the shank  8  of the tool  2  is inserted into the bore  34  of the block  30  from the first side  36 . The sleeve  50  is positioned about the shank  8  with the connecting surface  58  between the shank  8  and the surface of the bore  34 . The second end  56  of the sleeve  50 , up to and including the projected portion  80 , extends past the bore  34  on the second side  38  of the block  30  with the projected portion  80  of the sleeve  50  abutting the second side  38 . 
         [0026]    The sleeve utilizes two methods of retention—a friction fit as well as a rear retention. 
         [0027]    A friction fit for the sleeve  50  is established by the contact between the connecting surface  58  and the surface of the bore  34 . The connecting surfaces  58  are pushed radially outward against the surface of the bore  34  by a spring-like action of the sleeve  50 . The spring like-action occurs because the static-state diameter of the sleeve is larger than the diameter of the bore. When the projected portion  80  of the sleeve  50  exits the bore  34  on the second side  38  of the block  30 , the connecting surface  58  of the sleeve  50  expands to the diameter of the bore  34 . The elastic properties of the sleeve  50  provide for friction retention when installed. Note that the sleeve is depicted in  FIG. 1  as being located in only a portion of the bore  34 . That is, there is a portion of the shank  8  within the bore  34  that has the sleeve  50  arranged about it and there is another portion of the shank  8  within the bore  34  that does not have a sleeve  50  arranged about it. However, the sleeve  50  can occupy any length or longitudinally extent of the bore  34 . 
         [0028]    A rear retention for the sleeve  50  is established by the projected portion  80  abutting the second side  38 . The geometry of the projected portion  80  urges the tool  2  into the bore  34  of the block  30 , i.e., in an axial rearward direction (R). During use, as the tool  2  tries to kick out (and drag the sleeve  50  with it due to the second end  56  of the sleeve  50  contacting stop surface  90  located at the end of the shank  8 ), the angle (α) that starts the projected portion  80  provides, along with the elastic forces of the sleeve, a resistive force that urges the sleeve  50  (and therefore the tool  2 ) rearward (R). This maximizes tool retention and minimizes slapping between the first side  36  of the block  30 , i.e. the face, and the shoulder  14  of the tool  2 . 
         [0029]    By combining the holding features of a sleeve retainer with retention properties of a rear style retainer, the retention power for the sleeve is increased over designs using only one a friction fit and rear style retainer. The increased retention is more than enough to overcome the vibrations and centrifugal forces inherent in current and planned machine designs. 
         [0030]    When assembling the tool  2  into the block  30 , the sleeve  50  is preassembled about the shank  8 . This can be accomplished, for example, by sliding the sleeve  50 , typically in an expanded state, over the stop surface  90  of the shank  8 . Once the sleeve  50  is past the stop surface  90 , the sleeve  50  returns to the static state. The stop surface  90  prevents the sleeve  50  from coming off the shank unless the sleeve  50  is expanded by some means. 
         [0031]    When inserted into the bore  34 , the preassembled sleeve  50  is compressed by the surface of the bore  34  bearing on the projected portion  80 . In the area of the projected portion  80 , the shank  8  has a reduced radius or other accommodation, such as a slot, groove, trench or taper, to allow the sleeve  50  to compress as needed to pass the increased radius of the projected portion  80  through the bore  34 . 
         [0032]    In an exemplary embodiment, a customer receives the tool  2  with the sleeve  50  already assembled. Thus, the tool  2  comes ready for installation with no loose pieces. Because the tool  2  comes with the sleeve  50  in place, installation is very simple. By using a standard dead-blow hammer, the tool  2  is knocked into the block  30  (or similar holder). Once the projected portion  80  of the sleeve  50  exits the bore  34  on the second side  38  of the block  30 , the sleeve  50  expands. The projected portion  80  behaves as a rear retainer and the connecting surfaces  58  act as a friction fit, locking the tool  2  in its block  30  without inhibiting rotation. 
         [0033]    This retention method can be used with blocks that have internally grooved bores or smooth bores. Internally grooved bores are not needed for this sleeve, although they will not diminish the performance of the tool or the retention method. When an internally grooved bore is present, the connecting surface of the sleeve bridges the groove. During insertion of the sleeve in a grooved bore, the projected portion may expand into the groove. However, additional force can be used to recompress the sleeve and to continue insertion until the projected portion exits the bore on the second side of the block. 
         [0034]    Although described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without department from the spirit and scope of the invention as defined in the appended claims.