Turning – Severing or cut-off – Processes
Reexamination Certificate
2002-04-23
2003-05-27
Tsai, Henry W. H. (Department: 2183)
Turning
Severing or cut-off
Processes
C082S123000, C082S158000
Reexamination Certificate
active
06568303
ABSTRACT:
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 respe
Belasco David A.
Belasco Jacobs & Townsley LLP
Tsai Henry W. H.
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