Abstract:
A clamp for holding a cutting insert on a tool holder and having a coolant passage therethrough to receive a coolant from a coolant supply conduit external to the tool holder and into an inlet of the clamp, and to impinge a coolant stream emerging from an outlet of the coolant passage onto a cutting interface between the cutting insert and a work piece. The flow of coolant through the coolant passage extends the life of the cutting insert by reducing heat generation at the cutting interface between the cutting edge of the cutting insert and the work piece. The coolant passage can be formed using conventional drilling tools. The clamp enables the extension of the service life of a cutting insert and can be used with conventional tool holders.

Description:
FIELD OF THE INVENTION 
       [0001]    This application relates to a tool for removing material from a work piece, such as a metal work piece. More specifically, this application relates to a clamp to hold a cutting insert on a tool holder that is positionable to engage the cutting insert with a work piece to remove chips of material from the work piece. 
       BACKGROUND 
     Background of the Related Art 
       [0002]    The present invention relates to a clamp to hold a cutting inserts on a tool holder. Cutting inserts are detachably clamped on a tool holder that is controllably positionable relative to a work piece, generally a rotatable work piece. The work piece may rotate as the tool holder positions the cutting insert to engage the exterior of the work piece and to cut or remove chips of material from the work piece to obtain a desired exterior shape. 
         [0003]    Cutting inserts are often made with a plurality of cutting edges. The provision of two or more cutting edges on an insert makes the cutting insert more economical to use. The cutting insert is generally discarded when it becomes dull or chipped, and the life of a cutting insert is generally shortened by high temperatures at which a cutting insert is used. 
         [0004]    A cutting insert must be securely held in place in a pocket on a tool holder during the cutting operation. When the inserts are of a substantial area, it is possible to fix the insert both accurately and firmly within the pocket of a tool holder by providing the insert with a central hole and the tool holder with a pin-type clamping device. In other cases, such inserts may be held in place by a top clamp. Examples of such holders are found in U.S. Pat. Nos. 3,754,309; 3,399,442, 3,762,005 and 4,834,592 and British Patent No. 1,363,542. 
         [0005]    The main object of metal machining is the shaping of the exterior surface of the work piece. Much attention is paid to the formation of chips during the machining process, even though the chip is a waste product. The work piece is generally rotated using a spindle powered to rotate by a motor. The motor provides the power to keep the work piece turning at a generally uniform rate notwithstanding the drag and friction introduced by engagement of the cutting insert with the exterior surface of the work piece. The consumption of energy and the generation of heat occur mainly in the formation of metal chips. 
       BRIEF SUMMARY 
       [0006]    One embodiment of the present invention comprises a clamp to secure a cutting insert to a tool holder, the clamp being connectable to a coolant supply conduit that is external to the tool holder and comprising a proximal portion with a toe, a distal portion with a heel, an aperture intermediate the proximal portion and the distal portion to receive a fastener, such as a screw or bolt, through the clamp to engage a hole in the tool holder, and a coolant passage having an inlet to the coolant passage in the distal portion of the clamp to receive a flow of coolant from the coolant supply conduit, an outlet from the coolant passage in a proximal portion of the clamp to direct a stream of coolant to impinge on the work piece adjacent to a cutting interface between a cutting edge of the cutting insert and a work piece engaged thereby, and an intermediate portion of the coolant passage between the inlet and the outlet and passing laterally to the aperture of the clamp, wherein the toe on the proximal portion of the clamp engages a receiving groove on the cutting insert to secure the cutting insert in position on the tool holder and against dislodgment from the forces applied by engagement of the cutting insert with the work piece, wherein the heel on the distal portion of the clamp engages a receiving détente to position the clamp relative to the tool holder, wherein the flow of coolant through the coolant passage of the clamp, at coolant temperatures at or near ambient temperature or below, lubricates the cutting interface to reduce the amount of heat generated at the interface and transferred to the cutting insert held in place on the tool holder using the clamp. A secondary benefit of coolant flow through the coolant passage of the clamp is that heat can be removed from the clamp to the coolant flow stream. 
         [0007]    Another embodiment of the present invention provides a threaded inlet in the distal portion of the clamp to connect the coolant supply conduit that is external to the tool holder. The coolant supply conduit connects to the threaded inlet of the clamp using a threaded end connection, and provides a flow of coolant from the coolant supply conduit, through the threaded end connection on the coolant supply conduit, through the inlet and the coolant passage of the clamp to the outlet. 
         [0008]    Another embodiment of the present invention provides a plurality of inlets in the distal portion of the clamp to enable the connection of the threaded end connection on the coolant supply conduit to a selected inlet on the clamp. This embodiment provides flexibility so that the coolant supply conduit can be connected to the clamp without crossing the coolant supply conduit over the tool holder or without otherwise impairing access to the fastener that secures the clamp to the tool holder. An inlet that is not in use can be isolated using a threaded plug. 
         [0009]    Embodiments of the present invention generally require that the clamp be rigid, made of a material that can be forcibly secured to the tool holder using a fastener and securable on a tool holder without substantial flexure so that the cutting insert is held fast against movement by forces generated in removing chips of material from the work piece. The coolant passage in the clamp can be formed in segments using a drill bit of sufficient hardness. For example, tungsten carbide drill bits are suitable for drilling segment of the coolant passage in the clamp. A drill bit is generally useful for forming only straight channels, and the formation of the coolant passage using drill bits may require the formation in the clamp of a plurality of intersecting channel segments that together form the coolant passage. 
         [0010]    Embodiments of the clamp of the present invention include an outlet from the coolant passage directed to impinge a stream of coolant onto the cutting interface between the cutting edge of the cutting insert and the work piece. The impingement of the stream of coolant lubricates and cools the cutting interface. The lubrication effect reduces the overall amount of heat generated in the cutting insert as a result of the formation and removal of chips of material. The continuous flow of coolant through the coolant passage in the clamp also removes some heat from the clamp and thereby has an additional cooling effect on the cutting insert. The resulting operating temperature of the cutting insert is reduced and the life of the cutting insert is increased. Preferably, the outlet of the coolant passage in the clamp is directed to impinge a stream of coolant on the cutting interface below a chip of material as it is being formed by removal of material from the work piece and above the cutting edge of the cutting insert. Impingement of the stream of coolant below the chip being removed and above the cutting edge of the cutting insert provides the most beneficial lubrication and reduction in heat generated by the machining process. 
         [0011]    Embodiments of the clamp of the present invention may be advantageously used with existing tool holders and with existing inventories of cutting inserts to save substantial costs. In one embodiment, the clamp of the present invention comprises two inlets, each of which is in coolant communication with the coolant passage through the clamp to enable connection to a coolant supply conduit from either side. In this embodiment, an inlet that is not connected to the coolant supply conduit may be closed using a threaded plug. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view of a conventional tool holder having a pocket in which a cutting insert is received and secured using a clamp of the present invention. 
           [0013]      FIG. 2  is a plan view of an embodiment of a clamp of the present invention. 
           [0014]      FIG. 3  is an elevation view of the clamp of  FIG. 2 . 
           [0015]      FIG. 4  is the perspective view of  FIG. 1  with dotted lines illustrating the position of a portion of a work piece to be engaged by the cutting insert held on the tool holder by an embodiment of the clamp of the present invention. 
           [0016]      FIG. 5  is a plan view of an alternative embodiment of the clamp of the present invention. 
           [0017]      FIG. 6  is a plan view of another alternative embodiment of the clamp of the present invention. 
           [0018]      FIG. 7  is a perspective view of a conventional tool holder having a pocket in which a cutting insert is received and secured using the alternative embodiment of the clamp of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  is a perspective view of a conventional tool holder  19  having a pocket  47  therein which a cutting insert  39  is received and secured using a clamp  10  of the present invention. The tool holder  19  is generally connected to and controllably movable using, for example, precision hydraulics (not shown) that provide for smooth and reliable positioning of the cutting insert  39  secured in the pocket  47  for movement with the tool holder  19  relative to the work piece (not shown) from which material chips are removed using the cutting insert  39 . A support member  37  may be received into the pocket  47  and supported on the floor  38  of the pocket  47  prior to receiving the cutting insert  39  to act as a buffer or cushion between the cutting insert  39  and the pocket  47  and to prevent unwanted deformation of the pocket  47 . It will be noted that the pocket  47  has a rear wall  49  at an angle to the floor  38  to better secure the cutting insert  39  in the pocket  47 . 
         [0020]    The tool holder  19  comprises a threaded hole (not shown) to receive a fastener  40 . The clamp  10  of the present invention comprises an aperture  12  (not shown in  FIG. 1 ) to receive the fastener  40  to secure the clamp  10  to the tool holder  19  at the threaded hole (not shown). In the embodiment of the clamp  10  of  FIG. 1 , the clamp  10  comprises a first inlet (not shown in  FIG. 1 ) having threads for being sealably connected to a threaded fitting  32  on an end  31  of the coolant supply conduit  30 . The clamp  10  of  FIG. 1  further comprises a second inlet (not shown), generally opposite the first inlet, and having threads (not shown) for being sealably connected to a threaded plug  33  to close the second inlet while not in use. It will be understood that the provision of the first inlet and the second inlet in the clamp  10  enables the convenient connection of the coolant supply conduit  30  on either side of the clamp  10 . It will be further understood that embodiments of the clamp  10  of the present invention may comprise only a single inlet. The clamp  10  of  FIG. 1  comprises an outlet  11  directed to impinge a coolant stream provided from the coolant supply conduit  30 , and through a coolant passage (not shown in  FIG. 1 ) in the clamp  10 , onto a cutting interface between the cutting edge  17  of the cutting insert  39  and the work piece (not shown). 
         [0021]      FIG. 2  is a plan view of another embodiment of the clamp  10  of the present invention with dotted lines used to reveal internal structures. The clamp  10  of  FIG. 2  comprises a first lateral side  20 , a second lateral side  21 , a distal wall  19  along a distal portion  29  of the clamp  10 , a coolant passage  36  fluidically connected, at a first end, to an inlet  13  in the distal portion  29  of the clamp  10  that is adapted to sealably receive a threaded fitting  32  (not shown in FIG.  2 —see  FIG. 1 ) on the end  31  of the coolant supply conduit  30 . The coolant passage  36  is fluidically connected at a second end to the outlet  11  in a proximal portion  22  of the clamp  10 . The outlet  11  is directed to impinge a stream of coolant emerging from the coolant passage  36  onto an interface between the cutting edge  17  (not shown in FIG.  2 —see  FIG. 1 ) of the cutting insert  39  and the work piece (not shown). The clamp  10  of  FIG. 2  further comprises an aperture  12  to receive a fastener  40  (not shown in FIG.  2 —see  FIG. 1 ). The aperture  12  is intermediate the proximal portion  22  and the distal portion  29  of the clamp  10 . The inlet  13  comprises a well  16  having threads  15  provided therein for making up a sealed threaded connection with the threaded fitting  32  (not shown in FIG.  2 —see  FIG. 1 ) on the end  31  of the coolant supply conduit  30 . 
         [0022]    It will be understood that the position of the outlet  11  of the coolant passage  36  of the clamp  10  relative to the cutting edge  17  of the cutting insert  39 , and the direction of the coolant stream emerging from the outlet  11  of the coolant passage  36  of the clamp  10 , together determine the location on a work piece (not shown) at which the coolant stream impinges upon the work piece. This concept is illustrated in  FIG. 4  and discussed further below. The clamp  10  of the present invention is adapted to impinge the coolant stream emerging from the outlet  11  at a location on the work piece below the chip being removed and above the cutting edge  17  of the cutting insert  39 . This strategic placement of the coolant stream provided by embodiments of the present invention prevents unwanted shielding of the cutting edge  17  of the cutting insert  39  by the chip of material being removed from the work piece which acts as an umbrella to impede a stream introduced from a position above the clamp  10 . 
         [0023]    The position of the outlet  11  and the direction of the coolant stream emerging therefrom is determined by the physical configuration of the clamp  10 . The coolant passage  36  includes an intermediate channel  23  and an outlet channel  24  terminating at the outlet  11 . It will be understood that the inlet  13 , the intermediate channel  23  and the outlet channel  24  that together make up the coolant passage  36  in the clamp of  FIG. 2  may be formed using a conventional drill bit (not shown), and that a drill bit generally includes a conical or beveled tip that provides better penetration and chip removal during the drilling process. A conventional drill bit will, therefore, bore generally straight channels terminating at conical or beveled portions  34  and  26 . It will be understood that, in  FIG. 2 , intermediate channel  23  can be drilled from and through well  16  of the inlet  13 , and that intersecting outlet channel  24  can be drilled by initially creating the outlet  11  and then extending the outlet  11  to form outlet channel  24  to intersect with intermediate channel  23  at intersection  35 . Intermediate channel  23  and the well  16  of the inlet  13  intersect at intersection  25 . 
         [0024]      FIG. 3  is an elevation view of the clamp  10  of  FIG. 2  as seen from the first lateral side  20  (as shown in  FIG. 2 ) and illustrating the internal structures. The inlet  13  in the distal portion  29  includes the well  16  and the threads  15  therein, and the proximal portion  22  includes the outlet channel  24 . The intermediate channel  23  fluidically connects to the inlet  13  at intersection  25  and to the outlet channel  24  at intersection  35 . The intermediate channel  23  passes from the distal portion  29  to the proximal portion  22  laterally to the aperture  12  (see plan view in  FIG. 2 ). The aperture  12  that receives the fastener  40  (see  FIG. 2 ) is not shown in  FIG. 3  but is behind the intermediate channel  23  revealed in  FIG. 3 . The strategic placement and sizing of the inlet  13 , the intermediate channel  23  and the outlet channel  24  within the clamp  10  of  FIG. 3  will maximize the capacity of the clamp  10  to sustain a load applied downwardly on the clamp  10  by the fastener  40  (see  FIG. 1 ) and transferred through the clamp  10  to bear on the heel  28  and to the toe  27  to secure the cutting insert  39  (not shown in FIG.  3 —see  FIG. 1 ) to the tool holder  19 . 
         [0025]      FIG. 4  is the perspective view of  FIG. 1  with a portion of a work piece  50  in dotted lines to illustrate the position of a work piece  50  engaged by the cutting insert  39  secured on the tool holder  19  by the clamp  10 . The work piece  50  is supported on a spindle (not shown) that rotates the work piece  50  to move an exterior surface  53  of work piece  50  in the direction of arrow  55  as the cutting edge  17  of the cutting insert  39  engages the exterior surface  53  of the work piece  50  to remove material therefrom by the formation of chips (not shown). The coolant stream  52  emerging from the outlet  11  of the clamp  10  is directed to impinge on the cutting interface between the cutting edge  17  and the exterior surface  53  of the work piece  50 . The clamp  10  of  FIG. 4  includes a plug  33  sealably received in a second inlet (not shown) to accommodate connection of the threaded fitting  32  at the end  31  of the coolant supply conduit  30  on either side of the clamp  10 . 
         [0026]      FIG. 5  is a plan view of an alternative clamp  10  of the present invention in which an alternate location of the inlet  14  to the coolant passage  36  is illustrated. The clamp  10  of  FIG. 5  includes a proximal portion  22  and a distal portion  29 , a first side  20  and a second side  21 , and an aperture  12  therebetween to receive a fastener (not shown). The inlet  14  remains in the distal portion  29  of the clamp  10 , but does not open into the distal wall  19  of the clamp  10 . In the embodiment of  FIG. 5 , the coolant passage  36  comprises the inlet  14 , which includes a well  18  and threads  17  therein, an initial channel  56  drilled into the distal portion of the clamp  10  from the inlet  14  to establish coolant communication between with the intermediate channel  23  at intersection  57 . Intermediate channel  23  is bored from the distal wall  19  of the clamp  10  through a drilling access bore  60  having a well  62  with threads  61  therein to receive a threaded plug  69  to close the drilling access bore  60  and to isolate the coolant passage  36  to communicate only with the inlet  14  and the outlet  11  connected thereto. The intermediate channel  23  is connected to the outlet channel  24  at intersection  34 . 
         [0027]      FIG. 6  is another alternate embodiment of the clamp  10  of the present invention including an inlet  13  disposed at an angle to the second side  21  and also to the distal wall  19  of the distal portion  29  of the clamp  10  to accommodate a different angle and configuration for the connection of the coolant supply conduit  30  (not shown) and the threaded fitting  32  at the end  31  of the coolant supply conduit  30  (not shown). The embodiment of the clamp  10  of  FIG. 6  comprises an aperture  12  to receive a fastener (now shown) and a coolant passage  36  extending from the inlet  13  to the outlet  11 , and passing laterally to the aperture  12 . The coolant passage  36  comprises the inlet  13 , having a well  16  and threads  15 , an intermediate channel  23  passing between a first side  20  and the aperture  12  and laterally to the aperture  12 , an outlet channel  24  and the outlet  11 . The intermediate channel  23  is connected at an intersection  25  to the inlet  13  and at an intersection  35  to the outlet channel  24 . The clamp  10  of  FIG. 6  further comprises a drilling access bore  60  having a well  62  with threads  61  to receive and mate with a threaded plug  69  to close the drilling access bore  60  and to isolate the coolant passage  36  to communicate only with the inlet  13  and the outlet  11  connected thereto. It will be understood that the drilling access bore  60  is provided to enable the drilling of the intermediate channel  23  of the coolant passage  36 . The embodiment of the clamp  10  of  FIG. 6  further comprises a shelf  65  to align and position a threaded fitting  32  (see  FIG. 1 ) for being threadably connected to the adjacent inlet  13 . 
         [0028]      FIG. 7  is a perspective view of another embodiment of the clamp  10  of the present invention secured in a pocket  47  of a conventional tool holder  19  using a fastener  40  received through the aperture  12  (not shown in  FIG. 7 ) of the clamp  10 . The clamp  10  of  FIG. 7  has an angled inlet (not shown in  FIG. 7 ), like the embodiment of the clamp  10  of  FIG. 6 , but includes a second inlet (not shown) closed using a plug  33 . It will be understood that the angled inlet  13  (not shown in  FIG. 7 ) allows the threaded fitting  32  on the end  31  of the coolant supply conduit  30  to be connected to the clamp  10  without unwanted bends in the coolant supply conduit  30 . 
         [0029]    It will be understood that the clamp of the present invention may comprise a conductive material suitable for optimizing heat transfer from the cutting insert to the clamp and/or to optimize heat transfer from the clamp to the coolant stream flowing from the inlet in the distal portion of the clamp, through the coolant passage, and exiting the clamp at the outlet in the proximal portion of the clamp. In one embodiment, heat transfer structures may be provided within the coolant passage to promote heat transfer from the clamp to the coolant stream. For example, but not by way of limitation, a portion of the coolant passage in the clamp of the present invention may be threaded or otherwise machined to provide fins or other protruding structures within the coolant passage to increase the effective heat transfer area within the coolant passage across which heat is transferred from the clamp to the coolant stream while in use. It will be understood that such structures, if provided, should not compromise the capacity of the clamp to transfer force applied to the clamp by the fastener received through the aperture to the cutting insert engaged by the toe of the clamp of the present invention. 
         [0030]    It will be understood that the coolant provided from the source of pressurized coolant, through the coolant source conduit to the coolant passage may be selected to maximize lubrication and heat prevention in the cutting insert. The coolant may also be selected for its heat carrying capacity, but the primary benefit is to minimize the amount of heat generated at the interface of the cutting edge of the cutting insert and the work piece. In one embodiment, the coolant comprises a water-based coolant including a lubricating substance or additive. Also, while embodiments of the clamp of the present invention illustrated in the appended drawings have a single outlet, it will be understood that other embodiments may include additional outlets from the coolant passage. 
         [0031]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components and/or groups, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 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. 
         [0032]    The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.