Abstract:
A tool retention apparatus for retaining a cutting tool in a tool holder which has a wedged shaped securing arrangement to hold the cutting tool against a pair of precision ground supports. The securing member provides both a vertical securing force and a radial location of the cutting tool to facilitate installation and removal of the cutting tool from a machine.

Description:
This Application is a divisional of Ser. No. 08/786,429, filed Jan. 21, 1997, now U.S. Pat. No. 5,878,642. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to manufacturing a form on the end of a shaft, i.e., blind spline tools mounted in tool holders, and more specifically to securing punches and dies to tool holders in individual or multiple tool arrangements. 
     2. Description of the Prior Art 
     Blind spline tools, i.e. punches and/or dies, individually or in multiple tool arrangements, have traditionally been held in position by precision grinding the major diameter or minor diameter of the cutting tool to very precise tolerances and mounting the cutting tool into tool holders having precision bores or pilots. Radial location is generally established by using a precision “V” slot or keyway. The “V” or keyway is manufactured in relation to the profile of the cutting tool and positioned central to the precision ground inside or outside diameter of the cutting tool. Most tools are retained by socket head cap screws threaded into the base of the tool holder. FIG. 6 shows such a prior art arrangement. A cylindrical cutting tool  100  is shown having a precision ground outer diameter  102  and an inner form ground master spline  104  which defines the cutting surface. The cutting tool  100  is secured to a cutting tool mounting block or holder  106  by securing bolts  108 . The tool holder has a cylindrical cavity  109  with a diameter closely toleranced to the outer diameter  102  of the cutting tool  100 . While the securing bolts  108  establish a location in a plane transverse to the axis of the cutting tool  100 , the radial position of the cutting tool  100  still needs to be accurately positioned. For this purpose a “V” notch  110  is typically used to provide such radial positioning. A securing member or “V” locator  112  is formed on the tool holder  106  so that the “V” notch  110  in the cutting tool mounts therein to provide the radial position of the cutting tool  100  with respect to the tool holder  106 . 
     To accommodate for the loss of the location in the transverse plane of the cutting tool when the cutter is sharpened by grinding the top of the cutting tool  100 , a riser shim (not shown) is mounted adjacent to the bottom of the tool between the cutting tool and the tool holder by cap screws  107 . This riser shim, which in thickness represents the metal removed from the top in sharpening the cutting tool, is usually attached to the bottom of the cutting tool after it is sharpened. Clearance holes for the screw heads which retain the riser shims to the cutting tool are provided in the tool holder. 
     To prevent a setup man from mounting the wrong cutting tool  100  in the wrong mounting block  106 , a selective interference is provided in the cutting tool mounting block cavity. This selective interference is most commonly accomplished by having a dowel pin  105  located in and protruding from the top face of the tool holder  106  which mates with a corresponding hole in the bottom of the cutting tool  100  in such a manner as to interfere with all but the correct cutting tool. The correct cutting tool will have a clearance hole in a predetermined location with respect to the “V” notch and the mounting hole pattern to receive the dowel pin protruding from the top face of the tool holder and therefore only the correct cutting tool will fit in a specific cavity in the tool holder. 
     To remove the prior art cutting tool  100  from its tool holder  106  it is required that the securing bolt  108  be removed, and the securing member  112  removed or retracted from the “V” notch  110 . Often the prior art cutting tool requires the use of jack screws to remove or lift the cutting tool  100  from the cavity in the precision tool holder  106 . The jack screws are required since the cylindrical cavity  109  in the tool holder  106  is precision ground to very close tolerances to match the outer diameter  102  of the cutting tool  100 . The need for the various accurate positioning surfaces and associated retaining devices results in an expensive cutting tool which is time consuming to remove from its tool holder. Accordingly, what is needed is a cutting tool which is inexpensive to manufacture and easy to install and/or remove from its tool holder as well as which offers more accuracy for positioning the cutting tool on the tool holder. 
     SUMMARY OF THE INVENTION 
     According to the present invention there is provided a blind spline cutting tool having two precision planar or flat faces which are machined in the periphery of the cutting tool along an outer edge of the cutting tool in spaced relation to each other and perpendicular to the bottom face of the cutting tool. A third planar or flat face is also machined in the periphery of the cutting tool along the outer edge opposite from the two precision planar faces. The third planar face is at an acute angle with respect to the bottom face of the cutting tool such that when contacted by a securing device, such as a wedge, an effective force will be generated so as to force the cutting tool firmly against the two precision planar faces and a base on the tool holder in order to accurately mount the cutting tool in the tool holder. In a preferred embodiment, the base or tool holder upon which the cutting tool is mounted has complementary riser blocks establishing abutment mounting faces in opposing spaced relationship. The planar face opposing the two precision planar faces on the cutting tool is spaced a predetermined distance from the complementary riser block mounted on the base or holder. When the cutting tool is mounted to the tool holder the two precision planar faces of the cutting tool are forced against mounting faces of the complementary riser blocks on the tool holder, by the use of a wedge lock mounted between the third planar face of the cutting tool and its complementary riser block. The wedge lock cooperates with the third planar face and the associated riser block to secure the cutting tool to its tool holder and prevents the cutting tool from pulling away from the base of the tool holder. This arrangement provides for radial alignment of the cutting tool as well as secures the cutting tool to its tool holder thereby eliminating the need for a “V” notch for establishing a radial position. 
     To accommodate resharpening of the cutting tool, riser shims are used to provide an adjustment to the height of the cutting tool. The riser shims are bolted to the bottom of the cutting tool. “Fool proofing” in the present invention is accomplished by positioning the riser shim holes in a different radial relationship to the precision planar faces on each cutter in a set and providing clearance holes in the tool holder in a pattern which assures that only the proper cutting tool with the proper shim is bolted in the corresponding tool holder. 
     Accordingly, it is an object of the present invention to provide a cutting tool retention device that provides for accurate positioning of a cutting tool by eliminating any clearance between the cutting tool and the tool holder. 
     It is a further object of the invention to provide a cutting tool retention device wherein the positioning of a cutting tool has improved accuracy in a radial direction. 
     It is a still further object of the present invention to provide a cutting tool retention device from which a cutting tool is easy to remove by backing off a single locking device. 
     It is another object of the invention to provide a cutting tool retention device for securing a cutting tool that requires only a single retaining device in an effort to reduce the time and effort required to change tools. 
     It is yet another object of the invention to provide a cutting tool retention device for a cutting tool that is inexpensive to manufacture. 
     It is an even further object of the invention to provide a blind spline tool retention device for a blind spline cutting tool that allows existing prior art cutting tools with screw holes to be reworked to conform to the new inventive cutting tool. 
     It is yet another object of the present invention to provide a securing apparatus for a blind spline cutting tool that provides a fool proofing mounting arrangement for both the cutting tool as well as its associated riser shim. 
     Other objects and advantages of the invention will be more apparent after a reading of the following detailed description taken in conjunction with the drawings provided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial plan view of the retention apparatus of an embodiment of the present invention; 
     FIG. 2 is a cross-sectional view of the retention apparatus along lines  2 — 2  of FIG. 3; 
     FIG. 3 is a plan view of the preferred embodiment of the present invention; 
     FIG. 4 is a break-away cross-sectional view of the securing system shown in FIGS. 2 and 3; 
     FIG. 5 is an exploded perspective view of the retention apparatus of the preferred embodiment; and 
     FIG. 6 is a plan view of a known prior art cutting tool mounted to the top of a tool holder. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As discussed hereinabove, the prior art tool holder consisted of a precision ground circular cavity into which was mounted a precision ground cylindrical cutting tool. As is clear to one skilled in the art, it is impossible to have zero tolerance between the outside diameter (O.D.) of the cutting tool and the inside diameter (I.D.) of the cavity in the tool holder. Therefore, this type of retainer system inherently has some built-in error when the radial wedge or key is moved into the “V” notch or key slot until surface-to-surface contact is obtained by the complementary O.D. of the cutting tool and I.D. of the cavity. The retention arrangement of the present invention eliminates the above described built-in error as is hereinafter discussed. 
     With reference to FIG. 1, there is shown a plan view of a cutting tool retention arrangement  10  according to an embodiment of the present invention. The cutting tool retention arrangement  10  includes a cutting tool  12  and a tool holder  14 . The cutting tool  12  has a peripheral edge  13  which is interrupted by three flat faces  16 ,  18 , and  20 . The flat or planar faces  18  and  20  are preferably parallel to the central axis of a spline form cutting edge  22 . However, such an arrangement is not essential for the retention system to operate according to the teachings herein. The flat face  16  is at an acute angle to a line parallel to the central axis of the spline form cutting edge  22  for a purpose to be discussed hereinafter. The spline form cutting edge  22  is shaped to the form of the impression desired to be cut by the cutting tool. The drawings illustrate a spline; however, it is understood that any desired form may be used as a cutting edge. 
     The beveled planar face  16  in the cutting tool  12  is formed at an acute angle to the peripheral edge of the cutting tool; which can vary, but which is, preferably, approximately 15°. A securing mechanism  30  in the form of a wedge lock arrangement, as hereinafter described with reference to FIG. 4, is mounted in a cavity  28  and makes contact with the beveled flat face  16 . The securing mechanism when mounted to the tool holder  14  locks the cutting tool  12  to the tool holder in two degrees of orientation. The first degree of securing is radial securing by forcing the flat faces  18  and  20  of the cutting tool  12  into flat faces  24  and  26  in the cavity of the tool holder  14 . The second degree of securing is provided in a downward direction toward the tool holder  14  as a result of the wedging action of the securing mechanism  30 . According to the present invention, the flat face  18  and the flat face  20  of the cutting tool  12  are precision ground, as are the flat faces  24  and  26  of the tool holder  14 . The ground face  24  and the ground face  26  directly contact the flat face  18  and the flat face  20  of the cutting tool  12  as the securing mechanism  30  is tightened. Since the flat face  18 , the flat face  20 , the flat face  24 , and the flat face  26  are all precision ground faces, precise radial positioning of the cutting tool  12  on its tool holder  14  is accomplished. It should be appreciated by those skilled in the art that the closer the tolerance obtained in manufacturing the flat faces  18  and  20  as well as the ground flat faces  24  and  26 , the higher the accuracy of the radial positioning of the cutting tool  12 . It is, therefore, desired that the faces  18  and  20 ,  24  and  26  be ground to the highest tolerances economically permissible. 
     The height of the cutting tool with respect to the tool holder may be adjusted by risers  36  which will hereinafter be described in detail. The riser is mounted directly to the bottom of the cutting tool  12 . As shown in FIG. 5, cap screws  27  and  29  attach the risers to the cutting tool  12 . The heads of the mounting members or cap screws  27  and  29  protrude from the bottom of the cutting tool  12  to provide a fool proof mounting of the cutting tool  12  to its appropriate tool holder  14 . The heads of the cap screws  27  and  29  fit into pilot holes  32  in the tool holder  14  as is more clearly depicted in FIG.  2 . Since more than one (often six) cutting tool  12  is used in the manufacturing of a spline on a shaft, it is desirable to provide a fool proof system that allows each cutting tool  12  to be installed only in its proper tool holder  14 . Such an arrangement is accomplished by locating the mounting members or cap screws  27  and  29  at unique radial positions on each of the various cutting tools  12  such that only the comparable tool holder will allow the correct cutting tool  12  to be mounted to it since the heads of the cap screws  27  and  29  are required to nest with the pilot holes in the tool holder  14 . 
     Referring to FIG. 2, a cross-sectional view of the tool holder  14  with the cutting tool mounted thereto is shown. FIG. 2 illustrates additional features not clearly shown in FIG. 1 which include the wedge lock arrangement  30 , the pilot hole  32 , the cap screw  29  and the riser  36 . The wedge lock arrangement  30  is shown and will be described in more detail with respect to FIG.  4 . The wedge lock arrangement  30  applies a force to the beveled planar face  16  of the cutting tool  12 . This force holds the cutting tool  12  against the riser  36  as well as pushes the cutting tool  12  into the flat faces  18  and  20  of the tool holder  14  shown in FIG.  1 . The riser  36  is chosen from a set of risers of various heights. The riser  36  adjusts the height of the cutting tool  12  by raising the cutting tool  12  a distance equal to the height of the riser  36 . Since the riser  36  is chosen from a set of risers having various heights, the height of the cutting tool  12  can be adjusted as needed. This adjustment is required since the height of the cutting tool  12  is reduced each time the cutting tool  12  is sharpened. The amount of metal removed during sharpening is compensated by increasing the thickness of the riser  36  such that the top surface of the cutting tool  12  is always located the same predetermined distance from the base of the tool holder  14  upon which it is mounted. 
     The positioning of the heads of the cap screws  27  and  29  in relation to the “V” notch  110  so as to provide a positioning safety for cutters and holders is not new. However, the risers  36  in prior art applications most often had to be made special for each holder/cutter arrangement due to the fact that the “V” locator  112  extended into the cutter body  102  to such an extent that the “V” locator  112  interfered with the riser  36  and a clearance notch larger than the “V” locator  112  was required in the riser  36 . The location of the clearance notch in the riser is in direct relationship to the clearance holes in the riser for the cap screws  27  and  29  and therefore a particular riser  36  was required for each different cutter. 
     The invention further reduces the cost of overall tooling due to the fact that, since the “V” locator  112  is no longer utilized in the invention, the riser  36  can be cylindrical in shape without a clearance notch and, by placing the clearance holes for the cap screw retainers  27  and  29  in the riser  36  in a fixed relationship to each other, one riser  36  can be used for all configurations of cutting the tool  12  and the tool holder  14  within a set of tools. Only the radial positioning of the fixed pattern for the cap screws  27  and  29  in relationship to the flats  24  and  26  need be utilized for cutter/holder positioning safety. 
     Referring now to FIGS. 3 and 5, the preferred embodiment of the present invention is shown. The tool holder  14  is modified to include three riser blocks  38 ,  40  and  42  to receive the cutting tool  12 . The riser block  38  has a first abutment face  44 , which is a precision ground edge, and a second abutment face  46  of the riser  40  also has a precision ground edge. Unlike the embodiment of FIG. 1, the preferred embodiment of FIGS. 3 and 5 provides an open segment  48  between the riser block  38  and the riser block  40  as well as two large arc-segment portions  50  and  52  between the riser block  38  and the riser block  40  and the riser block  42 . These open segments  48 ,  50 , and  52  provide easy access to the cutting tool  12  for removal of the cutting tool as well as allow shavings created when forming the part to be moved away from the cutting tool  12 . The ability to easily remove metal shavings reduces the potential of having to disassemble the tool holder  14  to remove the metal shavings. A wedge lock arrangement is shown which is similar to the wedge lock arrangement  30  shown in FIG.  1 . 
     FIG. 4 shows an enlarged detailed cross-sectional view of the wedge lock arrangement  30 . The wedge lock arrangement  30  includes a wedge member  60  having a first tapered edge  61 , a second tapered edge  62 , a threaded collar  58  having a cross pin  59 , and a retaining screw  56 . In assembly, the threaded collar  58  is threaded onto the retaining screw  56  to a predetermined location after the threaded screw is mounted through a hole  63  in the wedge member  60 . The cross pin  59  is then mounted in a hole  65  made in the threaded collar  58  as well as in the retaining screw  56 . After the threaded collar is in place the complete wedge lock arrangement  30  is then screwed into a threaded hole  17  made in the base of the tool holder  14  until the tapered edges  61  and  62  come into contact with the complementary tapered edges  15  and  16  of the respective cutting tool  12  and the riser block  42 . Note that when the wedge lock arrangement is in place holding the cutting tool  12  to its tool holder  14  the threaded collar  58  does not contact either the tool holder  14 , cutting tool  12 , or the wedge member  60  since the collar has no function during the locking of the cutting tool  12  to the tool holder  14 . However, when the cutting tool  12  is to be removed from its tool holder  14  the retaining screw  56  is turned counterclockwise to remove it from its threaded hole  17  in the tool holder  14 . Because of the functional engagement of the first and second tapered edges  61  and  62  with the tapered surfaces on the cutting tool  12  and the riser block  42 , the wedge member will remain in its locked position until the retaining screw  56  is sufficiently backed off and the threaded collar  58  comes into contact with the bottom surface of the wedge member  60 . As the retaining screw  56  is further turned counterclockwise to remove it from the tool holder, the threaded collar  58  now provides a lifting force to the wedge member  60  to overcome the residual frictional forces holding the wedge member  60  in place. Upon breaking away from its locked position the wedge member  60 , retaining screw  56 , threaded collar  58 , and cross pin  59  are removed from the cavity  28  and the cutting tool  12  may be removed from its holder. 
     An optional configuration of the wedge lock arrangement  30  is to make the tapered edge  61  parallel to the axis of the retaining screw  56 . While this configuration would be functional, it does not provide as great a holding force as the wedge lock arrangement  30  wherein both edges are tapered. By having both edges tapered, the wedge lock arrangement  30  will provide approximately twice the holding force to hold the cutting tool  12  to its tool holder  14 . One skilled in the art may appreciate the use of other wedge locking configurations to mount the cutting tool  12  to the tool holder  14 . 
     It should be appreciated that the wedge lock arrangement  30  applies forces across the cross section of the cutting tool  12 . The direction of these forces is shown by force direction arrows  64  and  66  in FIG.  4 . In contrast, the direction of force illustrated by arrows  67  and  68  in the prior art device depicted in FIG. 6 is in a direction outward from the “V” notch  110 . Experience has shown that this outward type force tends to induce premature failure of the cutting tool  12 . 
     As a result of the configuration of the tool holder  14  shown in FIGS. 1 through 5, accuracy in positioning the cutting tool  12  is improved because the clearance between the mounting block hole and the cutting tool, as shown in the prior art, is eliminated. Radial positioning is also more positive because the securing mechanism of the wedge lock arrangement  30  does not limit the accuracy by which the cutting tool  12  is positioned relative to the tool holder  14 . 
     The cutting tool  12  is easy to remove because when the retaining screw  56  of the wedge lock arrangement  30  is backed off, the cavity  28  provides a clearance which allows free removal of the cutting tool  12 . This is in sharp contrast with the prior art method that often requires jack screws to remove the cutter body from the precision hole. 
     Only one retaining device is required to hold the cutting tool  12  in place. This is in contrast to the prior art which requires a plurality of socket head screws in addition to a radial positioning device to hold a cutting tool in place. By reducing the number of parts necessary to secure the cutting tool  12  to a single wedge lock arrangement  30 , the time and effort required to change tools is greatly reduced. The typical time required to change a cutting tool in the prior art method is approximately 10 to 15 minutes. The time necessary to change the cutting tool in the present invention is 1 to 3 minutes. Furthermore, with the embodiment shown in FIG. 3, the metal shavings produced from cutting the part can be removed from the holder without having to disassemble the cutting tool  12  from its tool holder  14 . This “in-place” cleaning simply was not possible with the prior art. Since the retaining screw holes of prior art cutters have been eliminated, the cutter made according to the invention is less expensive to manufacture. 
     It is readily clear to a person skilled in the art that the preferred embodiment of the present invention can be reworked into existing cutters without having to replace the cutter body. 
     Since the “V” locator of the prior art has been eliminated, the need for different sharpening riser shims for each cutter detail in a set of tools has been removed and results in significant reduction of the overall tooling cost. A single riser design will fit all the cutters in a set. This significantly reduces the number of risers required to successfully operate a complete machining center. 
     Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described.