Abstract:
A cutting tool assembly mounted on a rotating drum and having a base block, a wear sleeve and a cutting bit wherein a seal is located between the base block and wear sleeve is disclosed. A fluid passage spans from the rotating drum to a discharge location between the wear sleeve and the shank of the cutting bit. The fluid lubricates the shank of the cutting bit and bore of the wear sleeve allowing the cutting bit to rotate freely within the wear sleeve. Rotation of the cutting bit promotes even wear and long life of the bit.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to tools and tool assemblies for mining and construction applications and, more particularly, is concerned with prolonging the life of the cutting tools in these applications. 
       BACKGROUND INFORMATION 
       [0002]    Cutting tool assemblies for such applications as mining or road milling typically comprise a cutting tool, rotatably mounted within a support block. The support block in turn is mounted onto a drum, chain or other body, typically by welding, which in turn is driven by a suitable drive means. A number of such support blocks carrying cutting tools are mounted onto said drum to continually mine and remove material such as coal, rock, asphalt or concrete. The material removed by the cutting tool is pulverized by the cutting tool as each tip is rotated about the drum or chain into contact with the material. Some of the pulverized material collides against the support block and other cutting tool structure. The continual collision of cutting pick and material being removed causes abrasion and wear of the cutting tool and any other components mounted on or near the support block. The wear leads to eventual failure of the tool necessitating downtime of the associated equipment so the worn parts can be replaced. 
         [0003]    Wear sleeves have been devised to help protect the front of support block and to provide easily replaceable wear components in comparison to the entire block. It is known to equip a cutting tool assembly with a spray nozzle for spraying fluid onto a cutting tool so as to cool the tool thereby lengthening tool life. It is also known that free rotation of a cutting bit within the support block of the cutting tool promotes tool life by promoting even wear of the cutting bit. Current cutting tool assemblies often affix a shank of the cutting bit within a bore or a wear sleeve of the support block or within the a bore of the support block so the bit can rotate within a bore. It is a common occurrence for the cutting bits to seize within the bore preventing free rotation of the cutting bit and causing premature failure of the cutting bit. 
         [0004]    The present invention has been developed in view of the foregoing. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides a cutting tool assembly including a support block, wear sleeve and cutting but which lubricates an interface of the cutting bit and the wear sleeve to promote even wear of the cutting bit thereby deterring premature failure of the cutting bit. A seal between the support block and the wear sleeve allows the fluid to pass from a passage in the support block to a passage in the wear sleeve. The wear sleeve passage discharges into a bore of the wear sleeve which holds a shank of the cutting bit. The fluid lubricates the space between the shank of the cutting bit and the bore of the wear sleeve. The lubrication promotes free rotation of the shank of the cutting bit within the bore of the wear sleeve. 
         [0006]    An aspect of the present invention provides a cutting tool assembly for use in mining or road milling, comprising a support block having a bore and a fluid passage; a wear sleeve having a shank structured to fit at least partially within the bore of the support block, a collar, a bore for receiving a cutting bit and a fluid conduit, the fluid conduit extending from the collar to bore of the wear sleeve; and a seal located between collar of the wear sleeve and the support block, wherein the seal has at least one channel capable of delivering fluid from the fluid passage of the support block to the fluid conduit of the wear sleeve. 
         [0007]    Another aspect of the present invention provides a method of lubricating a cutting tool assembly for use in mining and road milling comprising the steps of providing a cutting tool assembly with a support block, wear sleeve and cutting bit having a shank inserted into the wear sleeve and injecting a fluid between the wear sleeve and the shank of the cutting bit to lubricate the shank and permit the cutting bit to rotate. 
         [0008]    Yet another aspect of the present invention provides a method of lubricating a cutting bit for use in mining and road milling comprising the steps of providing a cutting tool assembly having a support block with a fluid passage, a wear sleeve inserted into the support block having a bore and a fluid conduit having a discharge end in the bore, a seal between a shoulder of the wear sleeve and the support block, the seal having at least one opening to allow fluid to pass from the fluid passage of the support block to the fluid conduit of the wear sleeve, and a cutting bit having a shank inserted into the wear sleeve; providing fluid to the support block whereby the fluid is conveyed through the fluid passage of the support block, through at least one opening of the seal, through the fluid conduit of the wear sleeve and into the area between the shank of the cutting bit and the bore of the wear sleeve. 
         [0009]    These and other aspects will become more apparent from the following description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a side view of a cutting tool assembly mounted on a drum according to one embodiment of the present invention. 
           [0011]      FIG. 2  is a cross-section view of the cutting tool assembly shown in  FIG. 1  according to one embodiment of the present invention. 
           [0012]      FIG. 3  is a top view of a seal for use with a cutting tool assembly according to one embodiment of the present invention. 
           [0013]      FIG. 4  is a section view of the seal of  FIG. 3  along section line A-A according to one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    For purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. In this application, the use of the singular includes the plural and plural encompasses singular, unless specifically stated otherwise. In addition, in this application, the use of “or” means “and/or” unless specifically stated otherwise, even though “and/or” may be explicitly used in certain instances. 
         [0015]    Referring now to  FIG. 1 , a cutting tool assembly  10  is shown according to one embodiment of the present invention. A support block  20  is structured and arranged to hold a wear sleeve  30 . The wear sleeve  30 , in turn, holds a cutting bit  40  which may have a hardened insert  50  at its tip. The hardened insert  50  often comprises a material such as cemented tungsten carbide, polycrystalline diamond or other suitable material. The supporting block  20  may be mounted on a pedestal  100  which may be mounted on a rotating drum  110 . Alternatively, the support block  20  may be mounted directly onto the rotating drum  110 . In either case, it will be appreciated by those skilled in the art that the pedestal or support block may be welded or otherwise mechanically fastened to a rotating drum  110 . 
         [0016]    Referring now to  FIG. 2 , a cross-section of the cutting tool  10  of  FIG. 1  is shown. A seal  60  separates a shoulder  36  of the wear sleeve  30  from the forward face  22  of the support block  20 . As used herein, the term “seal” refers to a device or substance used to join two things together and/or make something impervious. The wear sleeve  30  may have a shank  32  which is retained within a bore  21  of the support block  20 . The wear sleeve  30  may be secured in the bore  21  by any suitable means known to those skilled in the art, e.g., interference fit, mechanical fasteners and the like. 
         [0017]    Still referring to  FIG. 2 , the cutting bit  40  has a shank  42  with an annular recess  44 . The shank  42  of the cutting bit  40  is retained within a bore  31  of the wear sleeve  30 . In this embodiment, the annular recess  44  engages a spring clip  46  mounted inside the wear sleeve  30 . A washer  52  may separate the cutting bit collar  48  from the wear sleeve  30 . It will be appreciated that the cutting bit shank  42 , wear sleeve bore  31 , and support block bore may be situated about a common longitudinal axis  2 . 
         [0018]    Referring again to  FIG. 2 , water or any suitable lubricating fluid passes from a source internal to the rotating drum  110  through a fluid passage  112  of the rotating drum  110 . In certain respects, the fluid may be water with one or more treatments or additives such as a detergent. Fluid passage  112  is in fluid communication with a pocket  104  at the base of the pedestal  100 . The pocket  104  allows fluid to pass from the fluid passage  112  to the fluid passage  102  of the pedestal  100 . Mounting pins  70  may be used in conjunction with recesses  72  to ensure the support block  20  is properly aligned with pedestal  100 . In this manner, a fluid passage  80  of the support block  20  aligns with the fluid passage  102  of the pedestal  100 . 
         [0019]    The fluid passage  80  of the pedestal  100  is in fluid communication with a distribution channel  90  of the seal  60 . A series of openings  136  about the distribution channel  90  of the seal  60  allow fluid to pass to one or more fluid conduits  34  in the wear sleeve  30 . The fluid conduit  34  extends from the seal  60  to the annular ring  38  of the wear sleeve  30 . At this point, fluid can pass around the annular slot  38  of the wear sleeve  30  and recess  44  of the cutting bit  40 , around the spring clip  46  and between the shank  42  of the cutting bit  40  and bore  31  of the wear sleeve  30  before exiting through the front or rear of the bore  31  of the wear sleeve  30 . The fluid flow lubricates the area between the shank  42  and the bore  31  and helps to keep it free from dust and debris. This helps to keep cutting bit  40  rotating. Rotation of the cutting bit  40  promotes even wear and reduces the likelihood of premature bit failure. 
         [0020]    A more detailed view of the seal  60  is shown in  FIGS. 3 and 4  according to one embodiment of the present invention.  FIG. 3  shows a top face  130  of the seal  60 . The top face  130  of the seal  60  may have a top surface  132  which seats against the shoulder  36  of the wear sleeve  30 . A bottom surface  134  of the seal  60  may seat against the shoulder  22  of the support block  22 . The annular distribution channel  90  which is in the bottom surface  134  of the seal  60  opposite the depressions  136  receives fluid from fluid passage  80  of the support block  20 . As mentioned above, openings  136  intersect the annular distribution channel  90  at one or more locations. The openings  136  extend to the top face  130  of the seal  60  and transfer fluid from the annular distribution channel  90  to the fluid conduit  34 . 
         [0021]    In certain respects, the seal  60  is made from polyurethane, nitrile rubber, fluoroelastomer, ethylene propylene, natural rubber, silicone rubber, poly(tetrafluoroethene) (PTFE), polyoxymethylene and like material. In other respects, the seal is a metallic material. Although the seal  60  is shown, as an annular ring coaxially located about the shank of the wear sleeve, it is contemplated that the seal may be any suitable configuration for delivering fluid from the support block to the wear sleeve. For example, instead of extending around the shank of the wear sleeve, the seal may be entirely located adjacent shank of the wear sleeve and the fluid passage of the support block and the fluid conduit of the wear sleeve. 
         [0022]    Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.