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FIELD OF THE INVENTION 
       [0001]    The present invention relates to an apparatus for performing cutting operations by a mining machine and the method of making the apparatus. 
       BACKGROUND OF THE INVENTION 
       [0002]    Cutting chains are frequently found in mining operations, including in continuous longwall miners. These chains have tool bits mounted to them that act as picks to repeatedly break apart the surface being mined as the chain is driven around a sprocket. 
         [0003]    Although mining chains are well known in the prior art, previously known mining chains are prone to failure due to breakage rather than normal wear. Often, the point of failure in a cutting link occurs at spots that have been welded, especially where the tool bit holder attaches to the link body. Due to the repeated stress of the mining bits on the hard mining material, the welded locations can eventually break or fracture, thus causing the chain to fail. The structure and operation of a continuous miner and the cutting chain for mining machines is set forth in detail in U.S. Pat. No. 5,031,964, and is herein incorporated by reference for all that it teaches. 
         [0004]    As can be seen from the prior art depicted in  FIGS. 1-2 , the cutting links in a mining chain included hubs for mounting tool bits. These cutting links were constructed by welding a tool mounting hub  20  to a regular roller link of the chain. A shank access gap between the link body and a tool mounting hub  20  was formed by milling away or broaching a portion of the link body. Once the shank  26  of the tool bit  25  was placed in the tool mounting hub  20 , the shank access gap provided access for a C-ring retainer  29  to be placed around a recess in shank  26  thus securing tool bit  25  within the tool mounting hub  20 . 
         [0005]    However, as our own analysis has shown, the weld of the tool bit holder to the chain link is often the point of weakness. 
         [0006]    Prior cutting links that were cast instead of welded were unable to provide a strong link having the necessary features for modern mining chains. U.S. Pat. No. 3,968,995 also depicts a cutter link of a mining chain that includes a tool mounting hub that could either be welded or be integrally cast. However, this prior art cutting link employed an expanding ring around the shank of the tool bit that secured the shank within the mounting hub, making it difficult to replace. 
         [0007]    Another prior art cutting link is depicted in  FIG. 3 . As will be appreciated, the link contains shank access gap formed by a milled slot  106  wherein a C-ring retainer can be secured to the shaft of the tool bit. The milling potentially weakens the link and is an extra step during the manufacture of the link that adds to costs. We disclose herein a cutting link that overcomes the disadvantages of the prior art. 
         [0008]    Another frequent area for failure of the mining chain occurs in the connection between links. The links of a mining chain are connected together by drive pins. However, the retention system for the drive pin uses dowel pins that can shear or break from lateral force or contact with the mining material. When this occurs, the chain breaks and the miner fails. 
         [0009]    The breakage of the chains results in significant downtime and loss of productivity as the continuous longwall miner can no longer function until the chains are repaired or replaced. We further disclose herein a drive pin retention mechanism that does not suffer from the problems of the prior art. 
       SUMMARY OF THE INVENTION 
       [0010]    We disclose herein a new link that is stronger than those described in the prior art. The claimed link does not employ welding to attach the tool bit holder, but instead is integrally cast as one piece. The cast link does not suffer the common failure at the weld and provides a much stronger link because you can put additional steel at the points you need it to give strength. 
         [0011]    The disclosed link also employs the use of a rubber sandwich pin or steel spring pin with a drive pin retainer that covers the rubber or steel pin to provide a superior retention system for the pin in the retainer thereby doing a better job of retaining the retainer on the drive pin. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Further advantages of the invention will become apparent by reference to the detailed description of preferred embodiments when considered in conjunction with the drawings: 
           [0013]      FIG. 1  depicts a portion of the mining chain of the prior art. 
           [0014]      FIG. 2  depicts a cutting link of the mining chain of the prior art. 
           [0015]      FIG. 3  is a cutting link of the mining chain of the prior art. 
           [0016]      FIG. 4  is a front elevation view of the presently disclosed cutting link. 
           [0017]      FIG. 5  is a right side view of the presently disclosed cutting link. 
           [0018]      FIG. 6  is a top side view of the presently disclosed cutting link. 
           [0019]      FIG. 7  is a rear elevation view of the presently disclosed cutting link. 
           [0020]      FIG. 8  depicts a perspective view of the presently disclosed drive pin with retention mechanism attached using a rubber sandwich pin. 
           [0021]      FIGS. 9A and 9B  depict a diagram of a drive pin and retainer used with a perpendicular rubber sandwich pin. Individually,  FIG. 9A  depicts a drive pin, and  FIG. 9B  depicts a retainer. 
           [0022]      FIG. 10  depicts a rubber sandwich pin to be used with the drive pin of  FIG. 9 . 
           [0023]      FIG. 11  depicts a drive pin and retainer secured with a rubber sandwich pin oriented in line with the drive pin. 
           [0024]      FIG. 12A-12D  depicts a D-shaped drive pin and retainer secured with a steel spring pin. Individually,  FIG. 12A  depicts a D-shaped drive pin and retainer secured with a steel spring pin.  FIG. 12D  depicts a D-shaped drive pin.  FIG. 12C  depicts a retainer.  FIG. 12D  depicts a steel spring pin. 
           [0025]      FIG. 13  depicts a threaded drive pin with retainer secured with a rubber sandwich pin oriented in line with the drive pin. 
           [0026]      FIG. 14  depicts a perspective view of a pivot pin. 
           [0027]      FIG. 15  depicts a perspective view of the presently disclosed chain pin. 
           [0028]      FIG. 16  depicts a perspective view of another embodiment of the presently disclosed mining pin. 
           [0029]      FIG. 17  depicts a perspective view of the presently disclosed mining pin retainer. 
           [0030]      FIG. 18A-D  depicts a perspective view of the one embodiment disclosed mining pin with retainer. Individually,  FIG. 18A  depicts a drive pin retention system.  FIG. 18B  depicts a retainer ring.  FIG. 18C  depicts a plastic seal.  FIG. 18D  depicts a dowel pin. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    The following detailed description is presented to enable any person skilled in the art to make and use the invention. For purposes of explanation, specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that these specific details are not required to practice the invention. Descriptions of specific applications are provided only as representative examples. Various modifications to the preferred embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the scope of the invention. The present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein. 
         [0032]    As will be also appreciated from  FIG. 4 , the presently disclosed cutting link  400  is integrally cast as a single link and tool mounting hub  420 . It does not require additional welding or milling. This link does not suffer the problems faced by the prior art cutting links because there are no welded joints. However, unlike prior integrally cast cutting links, the current invention includes a shank access gap  430  that allows tools bits to be secured through the use of a C-ring which can be removed when the tool bit needs to be replaced. Although depicted as located in the side, it should be appreciated that the shank access gap can also be located along the top of the cutting link  400 . Furthermore, the cutting link  400  has a structure that reduces the likelihood of fracturing under stressful conditions. The curved surface provides additional strength, especially along the convex surfaces of the tool mounting hub  420 . The unique shape of the cutting link  400  further allows for additional steel to be added at select locations to improve the strength of the link. Additionally, the bores of the cutting link  400  may be induction hardened to improve the life of the device without making it brittle. 
         [0033]    The cutting link  400  is designed to resemble other roller links found in the mining chain. It is comprised of a link body  401  that has a two transverse bores  410  at the longitudinal ends of the link body  401 , wherein each of the transverse bores  410  can accept a drive pin  840  (also called a pivot pin) to pivotally connect the cutting links  400  to other roller links in the mining chain. The leading transverse bore  410  is on the side of the cutting link  400  that approaches the surface being mined first when in normal use, with the trailing transverse bore  412  residing on the trailing side of the cutting link  400  and last to approach the mining surface. In a preferred embodiment, the roller links may be carburized as to harden the metal. 
         [0034]    An outwardly projecting tool mounting hub  420  extends from the link body  401  and has within it an open bore  422  through its length that is sized to snugly receive the shank  26  of a tool bit  25  (as pictured in  FIG. 2 ). The axis of the open bore  422  is angled relative to the length of the link body  401  such that when the shank  26  of the tool bit  25  is placed within the tool mounting hub  420 , the mining tip  27  of the tool bit  26  rises up and toward the leading edge of the cutting link (as viewed with the transverse bores level to the ground, and the leading transverse bore  411  closest to the mining surface). 
         [0035]    It should be appreciated that the tool mounting hub  420  may be angled to the left or right if it is a clearance bit intended to cut the kerf. The cutting tool bits depicted in  FIGS. 4-7  are angled at 24 degrees to the left of center. In a typical configuration, tool bits that are angled 24 degrees to the right would also be used, along with a tool bit angled 12 degrees to the right, a tool bit angled 12 degrees to the left, and a tool bit that is centered. 
         [0036]    In a preferred embodiment, the upper surface of the tool mounting hub  420  is connected to the trailing end of the link body  401  by a curved convex surface. This rigid section of metal provides additional support and structure to the cutting link  400  so that impact forces on the tool bit  25  during mining are distributed throughout the whole cutting link  400 , thus reducing stress on the tool mounting hub  420 . 
         [0037]    As can be seen in  FIG. 7 , the shank access gap  430  is a space in the side of the cutting link through which the shank of the tool bit can be accessed. The shank access gap  430  is accessible from one side of the cutting link, and is contiguous with the open bore  422 . The shank access gap  430  allows the shank  26  of the tool bit  25  to be accessed so that a C-ring retainer  29  can be placed on shank  26 , thus securing the tool bit  25  within the tool mounting hub  420 . When the tool bit  25  requires replacement, the C-ring retainer can easily be removed from the shank  26  through the shank access gap  430 . 
         [0038]    The cutting link  400  is made by casting it as one single piece and does not have any welds holding it together. As a result, it is a much stronger link. Where required, the cast can be constructed to add additional steel in areas that require greater strength, creating a cutting link that is as strong as any other link in the chain. 
         [0039]    It should be appreciated that the integral casting is much cheaper to make than forging and welding a link. Although an integral link having a tool mounting hub could be forged, it would require extensive drilling and machining to create the tool mounting hub and broaching to create the shank access gap. 
         [0040]    Another point of failure in mining chains of the prior art is in the retention mechanism that holds the drive pins  840  (also known as pivot pins) in place. The drive pin  840  is a generally cylindrically-shaped pin that passes through the transverse bores  410  of the mining chain links. It has a pin head  842  on one end and a fastener end  844  at the opposite end. 
         [0041]    Often, in the prior art, the drive pin  840  was held in place by a retainer  850  that surrounds the fastener end  844  of the drive pin  840 . A dowel pin was driven through a hole in retainer  850 , and through drive pin hole  848  in the side of the drive pin  840 . The dowel pin protruded through the retainer  850 , and could easily shear or break from the lateral force or contact with the mining material. When this occurs, the mining chain would break, and the miner fails. Some prior art roller links had protective rings surrounding the retainer that was intended to contain the dowel pin in its location. However, this protective ring could break off, and because there is no positive retention holding the dowel pin in, it could slide out. 
         [0042]    In the presently disclosed invention, the pivot pin has a retainer  850  held on by pins that are substantially flush with the retainer. In one embodiment, such as depicted in  FIGS. 8 ,  9 ,  10  and  12  a rubber sandwich pin  860  is used. The rubber sandwich pin  860  is constructed of two pieces of elongated metal pieces  864  with a rubber center  862  between them. The rubber center  862  is typically injected into the mold between the elongated metal pieces  864 , causing it to adhere to the two elongated metal pieces  864 . As can be seen from  FIG. 10 , the elongated metal pieces  864  are angled inwards toward the ends, with a middle section that is narrower. As the rubber sandwich pin  860  is driven into the drive pin hole  848 , it is compressed, and re-expands as it exits the other side of the drive pin  840 . This positive retention prevents the rubber sandwich pin from sliding out. 
         [0043]    In another embodiment, as shown in  FIG. 12   d  a steel spring pin  870  is used. The steel spring  870  has three prongs and a handle  872 . As the steel spring  870  shown in  FIG. 12   a  is pushed into the drive pin hole  848  of the drive pin shown in  FIG. 12   b , the outer prongs  874  extend outward as they pass into the interior of the drive pin hole  848 . Because of the spring force of the outer prongs  874  against the retainer  850  shown in  FIG. 12   c , the steel spring does not easily come out from the drive pin hole  848 . Once again, this positive retention keeps the steel spring pin from sliding out of the drive pin hole. 
         [0044]    Because this rubber sandwich pin  860  or steel spring pin  870  does not substantially protrude past the retainer, there is a significantly reduced chance that either pin will become damaged resulting in the retainer  850  separating from the drive pin  840 . 
         [0045]    Other potential retainers and dowel pins are shown in  FIGS. 14 to 18 . In another embodiment, a Hendrix pin or threaded steel pin with a castle nut is used. The castle nut can be held in place using a cotter pin. This is an excellent solution for repairs. 
         [0046]    The presently disclosed drive pin retention system can be used with any shaped retainer  850  that fits over the fastener end  844  of the drive pin  840 . In one embodiment, a D-shaped retainer is used in applications where the drive pin has at least one flat surface cut into the curved sidewall of the drive pin. In another embodiment, the drive pin  840  can be threaded such that the retainer  850  screws into place. Once the holes in the retainer and the drive pin hole  848  are aligned, a rubber sandwich pin or steel spring pin can be placed into the hole. 
         [0047]      FIG. 18A  shows another embodiment of a drive pin retention system. In this embodiment, the retainer  850  is placed over the fastener end  844  of the drive pin  840  (as numbered similarly to  FIG. 13 ). However, in this embodiment, the retainer  850  has two holes that pass all the way through the sidewalls of the retainer along the diameter of the retainer. The drive pin similarly has a drive pin hole  848  that passes through the drive pin  840 .  FIG. 18D  depicts a dowel pin  880  having two notched sections in the surface of the dowel pin such that the diameter at the notched sections is smaller than the diameter of the rest of the dowel pin  880 . The dowel pin  880  is intended to pass through the retainer  850  and the drive pin  840 .  FIG. 18B  depicts a retainer ring  882  having an interior diameter slightly larger than the diameter of the notched section, but smaller than the diameter at the unnotched section. The retainer ring  882  is able to open up slightly under pressure to accommodate the wider sections of the dowel pin  880 . This is accomplished by having the retainer ring  882  be C-shaped so that it can be forced to open wider. Alternatively, the retainer ring  882  can be made of a flexible material that allows it to open wider.  FIG. 18C  depicts a plastic seal  884  that is used to hold the retainer ring  882  in place in the holes of the drive pin  840 . The plastic seal  884  also helps prevent the steel pieces from weakening as they rub against each other. A plastic seal  884  and retainer ring  882  are used on each side of the drive pin  840  to keep the dowel pin  880  in place. 
         [0048]    As will be appreciated from FIG.  18 (A)-(D), the notched dowel pin  880  is held in place by two retainer rings  882  located in the holes of the drive pin  840 . Each of the two retainer rings  882  acts individually as a lock to keep the dowel pin  880  in place. The double locking mechanism ensures that the dowel pin  880  stays in place, even if one retainer ring  882  fails. 
         [0049]    To operate this drive pin retention system, the retainer  850  is placed over the end of the drive pin  840  such that the holes of the retainer  850  line up with the holes of the drive pin  840 . The dowel pin  880  is then hammered through the first hole of the retainer  850  and to the first hole of drive pin  840  which has a retainer ring  882  against its opening, held in place by the plastic seal  884 . The hammering of the dowel pin  880  causes the retainer ring  882  to open up as the dowel pin  880  is squeezed through. As the hammering continues, the dowel pin  880  will then pass through the second retainer ring  882  causing it to open up. As the leading notch of the dowel pin  880  passes through the second retainer ring  882 , the retainer  850  closes around the leading dowel pin notch. The first retainer ring  882  will then also close around the trailing notch. Thus, each retaining ring  882  will be wrapped tightly in a closed position around the notches of the dowel pin  880 . 
         [0050]    It should be appreciated that the cutting link  400  and the pin retention mechanism does not require a whole new mining chain, but instead can be employed by replacing specific links or the retainer cap. Furthermore, although the invention has been described for use with mining, it can be used in other applications, such as trencher chains. The pin retention system can also be used in any chain application. 
         [0051]    The terms “comprising,” “including,” and “having,” as used in the claims and specification herein, shall be considered as indicating an open group that may include other elements not specified. The terms “a,” “an,” and the singular forms of words shall be taken to include the plural form of the same words, such that the terms mean that one or more of something is provided. The term “one” or “single” may be used to indicate that one and only one of something is intended. Similarly, other specific integer values, such as “two,” may be used when a specific number of things is intended. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention. 
         [0052]    The invention has been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the invention. It will be apparent to one of ordinary skill in the art that methods, devices, device elements, materials, procedures and techniques other than those specifically described herein can be applied to the practice of the invention as broadly disclosed herein without resort to undue experimentation. All art-known functional equivalents of methods, devices, device elements, materials, procedures and techniques described herein are intended to be encompassed by this invention. Whenever a range is disclosed, all subranges and individual values are intended to be encompassed. This invention is not to be limited by the embodiments disclosed, including any shown in the drawings or exemplified in the specification, which are given by way of example and not of limitation. 
         [0053]    While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims. 
         [0054]    All references throughout this application, for example patent documents including issued or granted patents or equivalents, patent application publications, and non-patent literature documents or other source material, are hereby incorporated by reference herein in their entireties, as though individually incorporated by reference, to the extent each reference is at least partially not inconsistent with the disclosure in the present application (for example, a reference that is partially inconsistent is incorporated by reference except for the partially inconsistent portion of the reference).

Summary:
An improved cutting link and drive pin retention system for mining chains is disclosed. The cutting link is cast as a single piece instead of multiple parts welded together. The drive pin retention system further decreases the chance that the chain can break due to sheared dowel pins.