Work holders – Holder encloses work
Reexamination Certificate
2000-05-22
2001-05-29
Hail, III, Joseph J. (Department: 3723)
Work holders
Holder encloses work
C269S902000, C029S559000
Reexamination Certificate
active
06237907
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to workpiece holders used by machinists and to a method for using specialized workpiece holders to machine radius or diameter defined features at non symmetrical locations on workpieces. More particularly, the invention relates to an improved workpiece holder having a pair of individually adjustable jaws that allow a workpiece to be precisely translated along both X and Y axes while being rigidly retained in a V-block-like holder, and a method of using the holder for simple and rapid job set up to carry out the non symmetrical machining.
BACKGROUND
Machinists have been grappling with the problems of securely clamping and holding workpieces in order to carry out desired machining operations for as long as machine shops have been in existence. Due to the wide variety in sizes and shapes of workpieces, and the wide range of machining operations to be performed on them, machinists are continuously challenged to come up with the right workpiece holder for many unusual or specialized jobs. The venerable V-block emerged early on as the best multipurpose device in this regard, and has served thereafter as the baseline workpiece holder from which a wide range of variants have evolved. No matter what type of workpiece is involved—rectangular, cylindrical, curved castings, or other odd shapes big or small—and regardless of what type of machining operation is to be performed—grinding, drilling, cutting, milling, and so forth—there is most likely some form of V-block that will properly retain the workpiece while the operation is being completed.
Descriptions of typical prior art devices for clamping and holding workpieces during machining operations are found in a number of U.S. patents.
U.S. Pat. No. 1,372,661 to Secord discloses an early (1921) workpiece holding appliance having three separately adjustable jaws, each of which may be individually adjusted in both rotation and traverse.
U.S. Pat. No. 4,340,211 to Chiappetti discloses a V-block clamp having individually adjustable jaws that are directed mainly to holding items having curved outer surfaces, such as cylindrical workpieces. A cylindrical workpiece retained in the clamp disclosed would experience combined up/down as well as left/right movement in response to an adjustment of either jaw.
U.S. Pat. No. 4,583,432 to Bricker discloses a method of centering an article relative to a concentrically rotatable cylinder which includes a slightly adjustable centering member as part of a more or less conventional V-block device.
Additional teachings of various types of prior art workpiece holders are found in U.S. Pat. Nos. 3,887,202 to Zapart, 3,094,821 to Eckert and 1,349,963 to Jerrim.
Despite the generous number of devices and techniques taught in the prior art, it is not uncommon for a tool maker to have to make up special jigs for a particular unusual part or machining task. However, these one time “fixes” are time consuming, often requiring auxiliary elements such as shims, spacers, and the like, and rarely lend themselves to a high degree of precision repeatability for follow on finished articles. Additionally, most V-block based workpiece holders favor carrying out machining operations (especially grinding) at locations on the workpiece which are symmetrical with respect to the outer dimensions of the workpiece. Indeed, to machine or grind a radius or diameter on a workpiece with the center line not symmetrical with its outside surfaces has been declared by many great toolmakers to be one of the most difficult tasks to do or to teach. Even when this particular task is actually accomplished, the repeatability of the process for multiple workpieces remains difficult to achieve. It is precisely this set of needs that the present adjustable jaw workpiece holder meets, thereby satisfying a long standing need for a simple V-block based workpiece holder having a V-point that is rapidly and precisely adjustable along both X and Y axes.
OBJECTS OF THE INVENTION
It is therefore a primary object of the present invention to provide an improved adjustable jaw workpiece holder that overcomes the disadvantages of the prior art approaches.
A co-primary object of the present invention is to provide a method for machining a radius or diameter defined feature at locations on a workpiece that are not symmetrical with respect to the workpiece boundaries.
A further object of the present invention is to provide a workpiece holder having a pair of jaws that are individually adjustable along parallel axes such that the workpiece holder V-point can be smoothly and precisely shifted along a pair of orthogonal axes.
A still further object of the present invention is to provide an adjustable jaw workpiece holder wherein each of a pair of jaws is individually adjustable along a first axis and produces the effect of translating a workpiece retained between them along two axes.
A yet further object of the present invention is to provide an adjustable jaw workpiece holder wherein each of a pair of jaws is individually adjustable in position along first parallel axes responsive to the rotation to an adjusting screw or rack and pinion gearing, and is individually lockable in position responsive to the action of a locking screw or spring loaded cam or other camming action.
A still further object of the present invention is to provide a highly simplified method of establishing the exact workpiece location prior to being machined wherein a pair of orthogonally related dimensions on the workpiece permit rapid set up of the workpiece location for machining features at non symmetrical workpiece locations.
In a number of preferred, alternate and improved embodiments, a dual jawed adjustable workpiece holder is formed as a modified V-block device wherein the V-point may be precisely shifted in fine increments along both X and Y axes in response to movement of one or both jaws along the Y axis.
In preferred embodiments, the adjustable jaw workpiece holder includes a pair of mirror image jaws with workpiece engaging upper surfaces formed at 45 degree angles to yield the well known 90 degree V-block angle. The two jaws are slidably retained in a U-shaped central cavity formed into a rectangular overall device, the cavity defined by at least three walls rising from a base, and each jaw may be raised or lowered within the cavity by means of a lead screw, rack and pinion gearing, or worm gearing which are accessible through openings in the device base. After being set at the desired positions, such that the device's V-point is suitably positioned in the XY plane, individual locking screws or spring loaded or over TDC cams secure the jaws in position. In use, the adjustable jaw workpiece holder is used in combination with various surface grinding machines, clamping means and spin fixtures to implement a method for rapidly and precisely positioning and retaining a workpiece, on which a radius or diameter defined feature is to be machined at a non symmetrical location with respect to the workpiece boundaries, with a high degree of positional repeatability.
REFERENCES:
patent: 1349963 (1920-08-01), Jerrim
patent: 1372661 (1921-03-01), Secord
patent: 3094821 (1963-06-01), Eckert
patent: 3887202 (1975-06-01), Zapart
patent: 4340211 (1982-07-01), Chiappetti
patent: 5005813 (1991-04-01), Lawrence
patent: 5305557 (1994-04-01), Warncke
patent: 6065744 (2000-05-01), Lawrence
patent: 1097919 (1961-01-01), None
Cottone James F.
Hail III Joseph J.
Shanley Daniel
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