Abrading – Work holder – Clamp
Reexamination Certificate
2001-04-09
2002-07-23
Eley, Timothy V. (Department: 3723)
Abrading
Work holder
Clamp
C451S231000
Reexamination Certificate
active
06422931
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the field of tool manufacturing and remanufacturing and, in particular, to a fixture apparatus for holding and manipulating a workpiece and a system utilizing the same.
BACKGROUND OF THE INVENTION
The use of cutting tools having replaceable cutting inserts began as long ago as 1917, when Fred P. Lovejoy invented the use of replaceable blades in order to obtain the economic advantages of having to replace the dull portion of the tool not the whole tool itself.
The next major improvement in this process was the invention of the tungsten titanium carbide insert by Philip M. McKenna in 1938, especially for use in milling machines. A typical milling machine is an apparatus that features a rotating mill head having a number of indexable cutting inserts, where the rotating head is passed over the workpiece to remove material from the workpiece.
Since the time of the invention of the carbide cutting insert, tremendous effort has been made to understand the myriad factors affecting the performance of cutting inserts. These factors include insert geometry, insert construction, temperature, cutting forces, workpiece material characteristics, and chip control. In fact, Kennametal, Inc. founded by Philip McKenna, lists thousands of insert geometry, size, composition, and coating combinations in order to meet the requirements of differing applications. Despite the overwhelming number of inserts that are available, standard inserts are still “standardized”.
Inserts can be manufactured in various ways. The most common basic materials are tungsten carbide or tungsten titanium carbide combined with a metallic binder such as cobalt. It is also possible to construct inserts from ceramic material. These are referred to as Cermet. Various thin film coatings can be applied to the surface of the cutting insert. Examples of common thin film coatings are titanium nitride, aluminum oxide, chromium nitride, titanium carbo-nitride, titanium aluminum nitride and diamond. Coatings are used to improve the performance and durability of the insert. Each material/coating combination has a particular application to which it is most suited.
In addition to material choices, various basic geometric shapes can also be selected. The most common are the square, triangle, diamond rhomboid, rectangle, hexagon and round. Added to this complexity is a choice of fifteen different clamping options, five different cutting edge forms, dimension tolerance classification, insert thickness, etc,.
Some inserts have only one sharpened edge suitable for cutting. However, most indexable inserts have a plurality of cutting edges. Once a particular cutting edge has become dull, the insert is indexed in its holder to expose a new cutting edge. Until recently, it was widely held that an insert was useless once all of its cutting edges had been dulled. Accordingly, dulled inserts were typically discarded as scrap. The growing acceptance of remanufactured inserts has disproved the belief that dulled inserts are valuable only as scrap. In fact, inserts remanufactured using the present inventor's remanufacturing methods, disclosed and claimed in U.S. Pat. No. 5,957,755 and incorporated herein by reference, have found acceptance in industries, such as aerospace, automotive, toolmaking and heavy equipment, that had heretofore utilized only new cutting inserts. By remanufacturing their cutting inserts, companies have been able to customize their tools to achieve enhanced performance in their particular application, while realizing a significant cost saving on a per edge basis.
The remanufacturing process has typically involved clamping an insert into a single insert holder, sharpening one edge of the insert, unclamping and indexing the insert, and repeating this process until all edges of the insert are sharpened. Once the insert is completed, the insert is removed and another dull insert is completely sharpened. This process is advantageous for remanufacturing inserts in small quantities, as the time required for set-up is relatively low. However, the continuous unclamping and indexing required by this process is too time consuming to be cost effective when remanufacturing large quantities of the same insert. Given the widespread acceptance of remanufactured inserts, and corresponding increase in demand for these inserts, there is a need for a way to increase the volumes of inserts that are remanufactured.
In addition to the need for increased throughput of remanufactured inserts, experience has shown that certain geometries, such as the helical bias grinds disclosed in the inventor's U.S. Pat. Nos. 5,957,755 and 6,171,031, which is also incorporated herein by reference, are difficult, if not impossible, to mold into new inserts. Further, it has been found that users of ground inserts can achieve superior performance over new molded inserts due to the ability to achieve a keener edge and to inexpensively adjust top rakes to optimize the edge for a particular application.
One way to realize an increase in remanufacturing throughput and provide the advantages of a ground edge to both remanufactured and new inserts, is to purchase and operate sophisticated computer numerically controlled (CNC) grinding equipment. However, such a solution requires a significant capital investment in purchasing the necessary equipment. In addition, this equipment requires the retention of qualified programmers and operators, who are not found in abundance and, once found, must be paid relatively high salaries. This solution may be acceptable to large-scale manufacturers of new inserts but is generally not financially feasible for smaller scale manufacturers. Further, in order to maintain a cost advantage over new inserts, any machine for increasing remanufacturing throughput must be made at relatively low cost and must be operable by non-technical personnel.
A number of United States Patents address the problem of fixturing. However, each has significant drawbacks that make them unsuited to solve the present problem. For example, U.S. Pat. No. 5,226,637, titled “CLAMPING DEVICE”, discloses a clamping fixture utilizing a driving mechanism for driving an input member toward the clamp main body, and a wedge type converting mechanism for converting a driving force supplied to the input member from the driving mechanism into a clamping force against the workpiece.
This clamping device is effective in some applications, but is ineffective at securely clamping inserts on a high volume basis. First, this clamping device uses a manually actuated clamping screw as the driving mechanism, requiring too much time for clamping, unclamping, and indexing. Further, the movable jaw is driven in a single direction to force the workpiece against a fixed jaw. This unidirectional clamping allows the workpiece to move upward between the jaws, preventing the workpiece from being positively seated and, consequently, from being ground to the exacting tolerances required for a remanufactured cutting insert to be effective. Finally, it is not adapted to clamp a variety of workpieces and, therefore, is of limited usefulness in remanufacturing.
Another fixture is disclosed in U.S. Pat. No. 5,056,766, titled “PRECISION MACHINE VICE”. This patent describes a fixture that employs a fixed jaw and a moveable jaw and employs a series of notches in the base as a guide means to stabilize clamping. A pin engages, at its lower end, a guide with opposite flanges. The guide also has a central wedge with an arcuate load-bearing surface. The pin extends through a rotatable clamp disposed through an angling shoulder on the moveable jaw and into a chamber in the base for engagement with the guide means to insure precise positioning. Tightening the pin into the guide snugs the upper surface of the wedge, flange, or both, into engagement with the upper surface of the chamber of the base, causing the moveable jaw to move toward the stationary jaw.
As was the case with the patent described above, this device also uses a manually operable clamping screw an
Eley Timothy V.
Lawson, Philpot & Persson P.C.
Nguyen Dung Van
Persson Michael J.
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