Abstract:
A method and apparatus for cutting rings from ring forgings of titanium or related materials is described. The ring forging is gripped and rotated about its centerline in a centering chuck. A tool holder is mounted parallel to and spaced from the centerline of the forging. The displacement of the tool holder is controlled both along and perpendicular to the centerline. First and second cutter bars having first and second cutter bits are mounted to the tool holder. The first cutter bar is mounted so that it may be moved along a diameter of the ring forging with the second cutter bar moving along a line parallel to, coplanar with and spaced from this diameter. The second cutter bit is wider than the first cutter bit. The second cutter bit widens the cut made by the first cutter bit, thereby providing chip clearance and cooling for the ring being cut.

Description:
FIELD OF THE INVENTION 
     The invention pertains to metal cutting machines and methods. More particularly, the invention relates to machines that designed to divide ring forgings made of titanium and related materials into precision measured ring sections for further processing. 
     BACKGROUND OF THE INVENTION 
     Titanium and related materials are typically used for the manufacture of aircraft engine parts and other high-stress, high-temperature applications. These materials are necessarily difficult to cut or machine and tend to be expensive so it is desirable that waste should be minimized. These materials cannot be cut effectively using abrasive cut-off wheels or saws and managing the heat and waste material produced in typical dividing operations can be problematical. Cutting procedures that involve a machine lathe and an orthogonally mounted cutter bar tend to bind as the cut into the rotating ring forging becomes deeper. Further, heating of the ring forging and the tool also increases as the cut becomes deeper, affecting the accuracy of the cut. Also as the cut becomes deeper, it becomes more difficult to clear the chip stream from the area of the cut, further causing binding and possible tool breakage or damage to the rings being cut. It is often desirable to divide a piece of ring forging of such material into nearly identical size ring sections for further forging or machining. If the ring sections can be identically sized and a minimum of material lost in the cutting, the process will be more economical. 
     U.S. Pat. No. 5,806,386 issued to Risse, is directed to a parting off tool for a lathe having a cutting edge and a rubbing pad. The tool body, a planar plate of stainless steel or the like, has its base located within a tool holder or post. A cutting tip is located on the working edge and has a short sharp edge parallel to the axis of piece. A cutting gap is an interruption in the continuity of the working edge and leads into a chip clearance area that is an aperture completely through the thickness of tool body. Across the cutting gap from the cutting tip a rubbing pad is located. The rubbing pad may be a polished hardened removable attachment or simply may be a length of the working edge. 
     U.S. Pat. No. 4,452,112, issued to Alexander describes a method of parting metallic rings in which the vibrations generated during heavy-duty operations are minimized by the additional step of supporting the tool holder with side plates. The parting tool, an indexable and disposable insert, has a bore through its center for receiving a fastener that also is received by a shim seat that is seated upon tool holder. The tool holder has side plates to support the tool holder from vibrations due to the extremely high pressures generated in the parting of very large rings. The parting tool engages the surface of the rotating ring below the horizontal plane of the center of rotation. 
     U.S. Pat. No. 4,052,822 issued to Obear is directed to a method and apparatus for abrasively cutting objects by making a score cut with a previously used worn down abrasive cutting wheel. The abrasive sawing machine has a main frame with a saw housing which positions a large saw or cutting wheel and a smaller saw or cutting wheel for engagement with a metal object, such as a billet to be cut. The large cutting wheel is mounted on an arbor and is used as the main cutting wheel until its diameter is worn down and it becomes less efficient for cutting and is limited in size of the billets that can effectively be cut. The used wheel is then employed as the smaller cutting wheel for making the initial scoring cut. The smaller wheel is provided with an arbor that is located diametrically opposite the larger wheel providing maximum clearance between the wheels as they begin to approach one another while simultaneously cutting the billet. 
     The smaller cutting wheel, though of the same thickness as the larger wheel, is much more rigid and thus does not skid along the surface of the billet during the initial scoring cut. The small wheel is rotated in the opposite direction of that of the billet to provide a preferred cutting for accurate alignment of the scoring cut while recognizing that a dressing type wear will occur with shorter life. Once the scoring cut is made sufficiently deep, the larger cutting wheel is moved into engagement within the scoring cut. The larger wheel rotates in a direction similar to that of the billet, which is the preferred direction for maximum wearing life of the wheel. 
     U.S. Pat. No. 4,549,678 issued to Fuminier, discloses a method and apparatus for separating a cut tube end from a work piece to avoid the risk of the end damaging the cutting tool. During the cutting operation, the tool mills a circular groove in the wall of the tube. As tool starts the groove, a jack drives a separator roller in the direction of the groove and a wedge enters the groove with the roller centering itself on the groove. After the cut end is separated, a support arm receives it and stops its fall. The separator apparatus prevents the cut end from falling onto the edge of cutting tool, and damaging it. 
     U.S. Pat. No. 4,302,958 issued to Andriessen et al., is directed to a parting off rolling tool having three rollers. The parting off tool has a main tool head and a second tool head. The main tool head has a part off rolling tool and a further tool that is a grooving tool of smaller diameter having a V-shaped working surface. The second tool head has only a rolling tool. As the rolling tools and advance through the tube stock, the grooving tool reaches the surface of the tube stock so that by the time the parting groove is completed, the grooving tool has formed a substantially V-shaped circumferential locating groove that is spaced axially from groove by the center-to-center distance L. As the tube stock is advanced for the next cut, error is eliminated by locating the rolling tools in the groove. 
     While other variations exist, the above described designs for ring-cutting machines are typical of those encountered in the prior art. It is an objective of the present invention to provide for cutting of rings of precisely described dimensions from titanium and related materials. It is a further objective to provide such precision cutting with a minimum of waste. It is yet another objective of the invention to minimize heating of both the cutting tool and the work piece. It is still another objective to minimize any pollution produced by the cutting process. Finally, it is an objective of the invention to provide the above-described capabilities in an inexpensive and durable machine, which is capable of extended duty cycles, and that may be easily repaired and maintained. 
     While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified. 
     SUMMARY OF THE INVENTION 
     The present invention addresses all of the deficiencies of prior art ring cutting inventions and satisfies all of the objectives described above. 
     An apparatus for cutting rings from ring forgings of titanium or related materials providing the desired features may be constructed from the following components. Means for removably holding and rotating the ring forging about a longitudinal axis are provided. The longitudinal axis extends through a centerline of the ring forging. Means are provided for rotating the ring forging at at least one speed and in at least one direction. A tool holder is adjustably mounted spaced from and parallel to the axis. Means are provided for controlling a displacement of the tool holder from the means for holding the ring forging along the axis, thereby allowing an operator to determine a thickness of a ring to be cut from the ring forging. Means are provided for controlling a displacement of the tool holder from the axis to affect cutting of the ring from the ring forging. 
     First and second cutter bars are provided. The first and second cutter bars are removably mounted to the tool holder such that the cutter bars are positioned orthogonally with respect to the axis. The first cutter bar includes a first cutting bit. The first cutting bit has a first cutting edge of a first predetermined width. The first cutting edge is positioned to move along a diameter of the ring forging toward the axis. The second cutter bar includes a second cutting bit. The second cutting bit has a second cutting edge of a second predetermined width. The second predetermined width is wider than the first predetermined width. The second cutting edge is positioned to move along a line parallel to and spaced from the diameter. The line is coplanar with the diameter. The second cutting bit is located to engage the ring forging after the first cutting bit engages the ring forging as the first cutting edge is moved along the diameter. 
     In a variant of the invention, the apparatus for cutting rings from ring forgings of titanium or related materials may be constructed from the following components. A horizontal mounting surface is provided. A machine base is fixedly attached to the mounting surface. A rotating headstock is fixedly attached to the machine base. The headstock has a longitudinal axis of rotation parallel to the horizontal mounting surface. The headstock has a front face. The front face is orthogonal to the axis of rotation of the headstock. The headstock is capable of providing rotation at at least one speed and capable of providing rotation in at least one direction. 
     The front face is adapted to removably attach a clamping means parallel to the front face. The clamping means is capable of mounting a ring forging such that the centerline of the forging is collinear with the longitudinal axis of rotation of the rotating headstock. 
     A tool holder is adjustably mounted spaced from and parallel to the axis. Means are provided for controlling a displacement of the tool holder from the front face of the headstock along the axis, thereby allowing an operator to determine a thickness of a ring to be cut from the ring forging. Means are provided for controlling a displacement of the tool holder from the axis to affect cutting of the ring from the ring forging. First and second cutter bars are provided. The first and second cutter bars are removably mounted to the tool holder such that the cutter bars are positioned orthogonally with respect to the axis. 
     The first cutter bar includes a first cutting bit. The first cutting bit has a first cutting edge of a first predetermined width. The first cutting edge is positioned to move along a diameter of the ring forging toward the axis. The second cutter bar includes a second cutting bit. The second cutting bit has a second cutting edge of a second predetermined width. The second predetermined width is wider than the first predetermined width. The second cutting edge is positioned to move along a line parallel to and spaced from the diameter. The line is coplanar with the diameter. The second cutting bit is located to engage the ring forging after the first cutting bit engages the ring forging as the first cutting edge is moved along the diameter. 
     When the first cutting bit engages the ring forging as the forging is rotated toward the first cutting edge a cut of the first predetermined width will be produced. When the second cutting bit engages the forging, the cut will be widened to the second predetermined width and chips will be removed from the cut and heat produced by the first cutting bit will be reduced. 
     In a further variant of the invention, the clamping means is a centering three-jaw chuck. In still a further variant, the means for controlling the displacement of the tool holder from the axis further comprises a horizontal drive mechanism. The drive mechanism is capable of moving the tool holder toward the axis of rotation at at least one predetermined speed. 
     In another variant of the invention, each of the first and second cutter bars include a flattened rectangular bar. The bar has a first end, a second end, first and second parallel side edges, a first uniform thickness and at least one receiving notch. The receiving notch is located at either the first or second end adjacent either the first or second side edges. The receiving notch has an upper edge and a lower edge. The edges taper toward each other and terminate in a rounded release opening. The upper and lower edges have a convex profile and are sized and shaped to receive a tapered cutting bit. 
     At least one tapered cutting bit is provided. Each of the cutting bits has a cutting edge and upper and lower edges that taper toward each other. The upper and lower edges have a concave profile sized and shaped to fit slidably the convex profile of the upper and lower edges of the receiving notch. The first or second end of the bar is relieved so that when the cutting bit is installed in the receiving notch, the cutting edge will protrude beyond the first or second ends of the bar. 
     In still another variant, the tool holder includes a base. The base includes means for removably mounting the tool holder to the means for controlling a displacement of the tool holder. A tool bar mounting surface is provided. The surface is orthogonal to the base and orthogonal to the axis of rotation of the headstock. A horizontal receiving slot is located in the tool bar mounting surface and has parallel upper and lower edges. The horizontal receiving slot is sized and shaped to slidably fit the rectangular bar of the first cutter bar. The horizontal receiving slot has a depth slightly less than the first uniform thickness. The horizontal slot is located so that the first cutting edge of the first cutter bit can be moved along the diameter of the ring forging. 
     An angled receiving slot is provided. The angled slot is located in the tool bar mounting surface and has parallel upper and lower edges and is sized and shaped to slidably fit the rectangular bar of the second cutter bar. The angled receiving slot has a depth slightly less than the first uniform thickness. The angled slot is located so that the second cutting edge of the second cutter bit can be moved along the line parallel to and spaced from the diameter. The line is coplanar with the diameter. Means are provided for securing each of the first and second cutter bars to the tool holder. 
     In a final variation of the invention, the means for securing each of the first and second cutter bars to the tool holder includes at least two threaded holes penetrating the tool bar mounting surface on either side of the horizontal slot and the angled slot perpendicular to the mounting surface. At least one rigid plate is provided. The rigid plate has at least two holes located to slidably fit threaded bolts sized to fit the threaded holes. At least two bolts are provided. The bolts are sized and shaped to penetrate the holes in the rigid plate and engage the threaded holes without reaching a bottom of the threaded holes. When the first and second tool bars are located in the horizontal slot and the angled slot and the bolts penetrate the rigid plate and threadedly engage the threaded holes and are tightened, the first and second tool bars will be removably attached to the tool holder. 
    
    
     An appreciation of the other aims and objectives of the present invention and an understanding of it may be achieved by referring to the accompanying drawings and the detailed description of a preferred embodiment. 
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of the preferred embodiment of the invention; 
     FIG. 2 is a perspective view of the tool holder of the FIG. 1 embodiment with the first and second cutter bars secured thereto; 
     FIG. 3 is a side elevational view of the tool holder, first and second cutter bars and the first and second cutter bits engaging the rotating ring forging; 
     FIG. 3A is a detailed perspective view of one end of one of the cutter bars illustrating the tapered convex receiving notch for a cutter bit; 
     FIG. 3B is a detailed perspective view of a cutter bit illustrating its concave tapered upper and lower edges and cutting edge; 
     FIG. 4 is a side cross-sectional detail illustrating the first cutter bit engaging the ring forging ahead of the second cutter bit; 
     FIG. 5 is a plan view cross-sectional detail of the first cutter bit engaging the ring forging taken along the line  5 — 5  illustrating a cut of the first predetermined width; and 
     FIG. 6 is a plan view cross-sectional detail of the second cutter bit engaging the ring forging along the line  6 — 6  illustrating a cut of the second predetermined width. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1-6 illustrate an apparatus  10  for cutting rings  14  from ring forgings  18  of titanium or related materials providing the desired features that may be constructed from the following components. As illustrated in FIG. 1, means  22  for removably holding and rotating the ring forging  18  about a longitudinal axis  26  are provided. The longitudinal axis  26  extends through a centerline  28  of the ring forging  18 . Means  30  are provided for rotating the ring forging  18  at at least one speed and in at least one direction. A tool holder  34  is adjustably mounted spaced from and parallel to the axis  26 . Means  38  are provided for controlling a displacement  42  of the tool holder  34  from the means  22  for holding the ring forging  18  along the axis  26 , thereby allowing an operator to determine a thickness  46  of a ring  14  to be cut from the ring forging  18 . Means  50  are provided for controlling a displacement  54  of the tool holder  34  from the axis  26  to affect cutting of the ring  14  from the ring forging  18 . 
     As illustrated in FIGS. 2-6, first  58  and second  62  cutter bars are provided. The first  58  and second  62  cutter bars are removably mounted to the tool holder  34  such that the cutter bars  58 ,  62  are positioned orthogonally with respect to the axis  26 . The first cutter bar  58  includes a first cutting bit  66 . The first cutting bit  66  has a first cutting edge  70  of a first predetermined width  74 . The first cutting edge  70  is positioned to move along a diameter  78  of the ring forging  18  toward the axis  26 . The second cutter bar  62  includes a second cutting bit  82 . The second cutting bit  82  has a second cutting edge  86  of a second predetermined width  90 . The second predetermined width  90  is wider than the first predetermined width  74 . The second cutting edge  86  is positioned to move along a line  94  parallel to and spaced from the diameter  78 . The line  94  is coplanar with the diameter  78 . The second cutting bit  82  is located to engage the ring forging  18  after the first cutting bit  66  engages the ring forging  18  as the first cutting edge  70  is moved along the diameter  78 . 
     In a variant of the invention, the apparatus  10  for cutting rings  14  from ring forgings  18  of titanium or related materials may be constructed from the following components. A horizontal mounting surface  98  is provided. A machine base  102  is fixedly attached to the mounting surface  98 . A rotating headstock  106  is fixedly attached to the machine base  102 . The headstock  106  has a longitudinal axis of rotation  26  parallel to the horizontal mounting surface  98 . The headstock  106  has a front face  110 . The front face  110  is orthogonal to the axis of rotation  26  of the headstock  106 . The headstock  106  is capable of providing rotation at at least one speed and capable of providing rotation in at least one direction. 
     The front face  110  is adapted to removably attach a clamping means  114  parallel to the front face  110 . The clamping means  114  is capable of mounting a ring forging  18  such that the centerline  28  of the forging  18  is collinear with the longitudinal axis of rotation  26  of the rotating headstock  106 . 
     A tool holder  34  is adjustably mounted spaced from and parallel to the axis  26 . Means  38  are provided for controlling a displacement  42  of the tool holder  34  from the front face  110  of the headstock  106  along the axis  26 , thereby allowing an operator to determine a thickness  46  of a ring  14  to be cut from the ring forging  18 . Means  50  are provided for controlling a displacement  54  of the tool holder  34  from the axis  26  to affect cutting of the ring  14  from the ring forging  18 . As illustrated in FIGS. 2-4, first  58  and second  62  cutter bars are provided. The first  58  and second  62  cutter bars are removably mounted to the tool holder  34  such that the cutter bars  58 ,  62  are positioned orthogonally with respect to the axis  26 . 
     As illustrated in FIGS. 3-6, the first cutter bar  58  includes a first cutting bit  66 . The first cutting bit  66  has a first cutting edge  70  of a first predetermined width  74 . The first cutting edge  70  is positioned to move along a diameter  78  of the ring forging  18  toward the axis  26 . The second cutter bar  62  includes a second cutting bit  82 . The second cutting bit  82  has a second cutting edge  86  of a second predetermined width  90 . The second predetermined width  90  is wider than the first predetermined width  74 . The second cutting edge  86  is positioned to move along a line  94  parallel to and spaced from the diameter  78 . The line  94  is coplanar with the diameter  78 . As illustrated in FIG. 4, the second cutting bit  82  is located to engage the ring forging  18  after the first cutting bit  66  engages the ring forging  18  as the first cutting edge  70  is moved along the diameter  78 . 
     As illustrated in FIGS. 4-6, when the first cutting bit  66  engages the ring forging  18  as the forging  18  is rotated toward the facing first cutting edge  70  a cut  118  of the first predetermined width  74  will be produced. When the second cutting bit  82  engages the forging  18 , the cut  118  will be widened to the second predetermined width  90  and chips  122  will be removed from the cut  118  and heat produced by the first cutting bit  66  will be reduced. 
     In a further variant of the invention, as illustrated in FIGS. 1 and 2, the clamping means  114  is a centering three-jaw chuck  126 . In still a further variant, the means  50  for controlling the displacement  54  of the tool holder  34  from the axis  26  further comprises a horizontal drive mechanism  130 . The drive mechanism  130  is capable of moving the tool holder  34  toward the axis of rotation  26  at at least one predetermined speed. 
     In another variant of the invention, as illustrated in FIGS. 2,  3  and  3 A each of the first  58  and second  62  cutter bars include a flattened rectangular bar  134 . The bar  134  has a first end  138 , a second end  142 , first  146  and second  150  parallel side edges, a first uniform thickness  154  and at least one receiving notch  158 . The receiving notch  158  is located at either the first  138  or second  142  end adjacent either the first  146  or second  150  side edges. The receiving notch  158  has an upper edge  162  and a lower edge  166 . The edges  162 ,  166  taper toward each other and terminate in a rounded release opening  170 . The upper  162  and lower  166  edges have a convex profile  174  and are sized and shaped to receive a tapered cutting bit  66 ,  82 . 
     As illustrated in FIG. 3B, at least one tapered cutting bit  66 ,  82  is provided. Each of the cutting bits  66 ,  82  has a cutting edge  70 ,  86 , upper  178  and lower  182  edges that taper toward each other. The upper  178  and lower  182  edges have a concave profile  186  sized and shaped to fit slidably the convex profile  174  of the upper  162  and lower  166  edges of the receiving notch  158 . The first  138  or second  142  end of the bar  134  is relieved so that when in the cutting bit  66 ,  82  is installed in the receiving notch  158 , the cutting edge  70 ,  86  will protrude beyond the first  138  or second  142  end of the bar  134 . 
     In still another variant, as illustrated in FIGS. 1-3, the tool holder  34  includes a base  190 . The base  190  includes means  194  for removably mounting the tool holder  34  to the means  38 ,  50  for controlling a displacement  42 ,  54  of the tool holder  34 . A tool bar mounting surface  198  is provided. The surface  198  is orthogonal to the base  190  and orthogonal to the axis of rotation  26  of the headstock  106 . A horizontal receiving slot  202  is located in the tool bar mounting surface  198  and has parallel upper  206  and lower  210  edges. The horizontal receiving slot  202  is sized and shaped to slidably fit the rectangular bar  134  of the first cutter bar  58 . The horizontal receiving slot  202  has a depth  214  slightly less than the first uniform thickness  154 . The horizontal slot  202  is located so that the first cutting edge  70  of the first cutter bit  66  can be moved along the diameter  78  of the ring forging  18 . 
     An angled receiving slot  218  is provided. The angled slot  218  is located in the tool bar mounting surface  198  and has parallel upper  222  and lower  226  edges and is sized and shaped to slidably fit the rectangular bar  134  of the second cutter bar  62 . The angled receiving slot  218  has a depth  214  slightly less than the first uniform thickness  154 . The angled slot  218  is located so that the second cutting edge  86  of the second cutter bit  82  can be moved along the line  94  parallel to and spaced from the diameter  78 . The line  94  is coplanar with the diameter  78 . Means  230  are provided for securing each of the first  58  and second  62  cutter bars to the tool holder  34 . 
     In a final variation of the invention, as illustrated in FIGS. 2-4, the means  230  for securing each of the first  58  and second  62  cutter bars to the tool holder  34  includes at least two threaded holes  234  penetrating the tool bar mounting surface  198  on either side of the horizontal slot  202  and the angled slot  218  perpendicular to the mounting surface  198 . At least one rigid plate  238  is provided. The rigid plate  238  has at least two holes  242  located to slidably fit threaded bolts  246  sized to fit the threaded holes  234 . At least two bolts  246  are provided. The bolts  246  are sized and shaped to penetrate the holes  242  in the rigid plate  238  and engage the threaded holes  234  without reaching a bottom (not shown) of the threaded holes  234 . When the first  58  and second  62  tool bars are located in the horizontal slot  202  and the angled slot  218  and the bolts  246  penetrate the rigid plate  238  and threadedly engage the threaded holes  234  and are tightened, the first  58  and second  62  tool bars will be removably attached to the tool holder  34 . 
     The apparatus for cutting rings from ring forgings  10  has been described with reference to particular embodiments. Other modifications and enhancements can be made without departing from the spirit and scope of the claims that follow.