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EP-4741098-A2 - WORK HOLDING DEVICE

EP4741098A2EP 4741098 A2EP4741098 A2EP 4741098A2EP-4741098-A2

Abstract

A work holding device for removably attaching work pieces to the device. The work pieces may be provided with elongated wedge shaped channels along two sides thereof and an indexing aperture on their bottom surfaces. The work holding device has a body with one or more open slots for receiving clamping assemblies and has a first and second cavity configured to receive spring-biased locating pins. The one or more open slots may have the shape of a rounded polygon in cross section. The clamping assemblies have first and second wedge portions that engage with the channels on the sides of the work pieces to hold the work piece in position during machining operations. The materials and construction of the work holding device provide for strength, stability and precise positioning to optimize machining operations and reduce errors and waste.

Inventors

  • FONDA, BRIAN
  • ROBINSON, DANIEL M.

Assignees

  • Brinkman Products, Inc.

Dates

Publication Date
20260513
Application Date
20251105

Claims (14)

  1. A work holding device for removably attaching work pieces having elongated wedge-shaped channels along two sides thereof and at least one indexing aperture on its bottom surface, said work holding device comprising: a main body having a proximal end, a distal end, and a mounting surface disposed between the proximal and distal ends, the body including at least one elongate opening extending transversely therethrough and having a portion that intersects the mounting surface thereby defining at least one open slot in the mounting surface, and at least one locating pin aperture, the at least one locating pin aperture borders a cavity in the body, the cavity is configured to receive a locating pin having a first end and a second end disposed opposite the first end, the first end of the locating pin sized to slidably insert into the at least one indexing aperture of the workpiece; a biasing member disposed in the cavity and configured to bias the locating pin in the upward direction; at least one clamp assembly insertable into the at least one elongate opening and configured to engage the wedge-shaped channels in the work piece.
  2. The device of Claim 1 wherein the clamp assemblies further comprise a clamp rod having a body and an enlarged head, the body having threads along a portion of its length and the enlarged head having means for turning the rod, a first clamp dog having a threaded aperture configured to engage with the threads on the clamp rod and a first wedge portion that protrudes through said open slot when said clamp assembly is inserted into the at least one elongate opening, a second clamp dog having an opening configured to receive the body of clamp rod slidably therethrough, the enlarged portion of the clamp rod engaging with the second clamp dog around the opening and a second wedge portion that protrudes through said open slot when said clamp assembly is inserted into the at least one elongate opening, and a first spring disposed around the clamp rod between the first clamp dog and a dividing section, a second spring disposed around the clamp rod between the dividing section and a second clamp dog.
  3. The device of Claim 1, further comprising platforms extending above the mounting surface.
  4. The device of Claim 3, wherein when the work piece is mounted on the work holding device, the work piece engages the mounting surface and the platforms.
  5. The device of Claim 1, further comprising a tie bar that extends across a portion of the at least one open slot in the mounting surface.
  6. The device of Claim 1, wherein the biasing member is a coil spring.
  7. The device of Claim 1, wherein the body is constructed of cast iron.
  8. The device of Claim 1, wherein at least a portion of the at least one elongate opening is shaped to include the form of a rounded polygon.
  9. The device of Claim 8, wherein the rounded polygon is a triangle.
  10. The device of Claim 1, wherein the at least one locating pin aperture comprises multiple locating pin apertures having different diameters or shapes.
  11. The device of Claim 1, wherein the means for turning the rod comprises a hex shaped opening in a head on the clamp rod.
  12. The device of Claim 1, further comprising a wall bordering the cavity with a groove defined therein for receiving a retaining ring to prevent the locating pin from exiting the cavity.
  13. The device of Claim 12, wherein the locating pin has a shoulder defined between the first end and the second end, the retaining ring disposed in the cavity and configured to engage the shoulder on the locating pin to prevent the locating pin from exiting the cavity.
  14. The device of Claim 2, wherein the first spring and the second spring are coil springs.

Description

TECHNICAL FIELD The present invention relates to a work holding device for rigidly clamping a work piece for machining, and in particular to a device capable of securely supporting work pieces of varying size that is suitable for numerically controlled machining applications. BACKGROUND ART When raw material, or partially fabricated components, are to be machined, the work piece must be securely clamped to a base plate or some other manufacturing platform to hold the work piece stable at a precise, predictable position in a manner capable of resisting the forces on the work piece produced by the machining operation to be performed. Typical machining operations include drilling, boring, honing, grinding and milling. In computer numerically controlled (CNC) machining, for example, a machine tool such as a milling head is programmed to follow a very precise path. The work piece must be located extremely precisely relative to the CNC machine datum points/planes from which the machining path is related or measured. A number of different indexing and clamping systems have been developed to permit a work piece to be positioned at a specific location on a support plate. Frequently, the clamping means have fingers, jaws, straps or other means that extend over the side of the workpiece opposite the supporting surface. While generally effective, the upper surface clamps must be carefully positioned to avoid interference with the movement of the machine tool, such as a milling head, across the work piece. The upper surface clamping means also restrict the access of the cutting tools, such as end mills, to a portion of the work piece. Insufficient clamping pressure, or the use of too few clamps, may allow the work piece to shift during machining, resulting in wasted, out-of-tolerance products and potential damage to the machine tool. Too much clamping pressure may result in damage to the work piece either directly, or by elastically deforming the work piece resulting in out-of-tolerance machining operations. Further, errors in clamp placement may result in damage to the clamps, to the cutting tools, and to the machine tool. In many work piece operations, it is desirable to use a work holder that is equipped with jaws and a work surface that are at least as wide as the work piece being machined to insure that the work piece is adequately supported during the machining operation. Moreover, with increasing use of numerically controlled machines the work piece must be clamped to the work platform at a very precise, or indexed, location so that the preprogrammed machining process will produce the desired operations. It is frequently desirable to present multiple work pieces to the machining apparatus, and to be able to machine all surfaces of the work piece in a single operation, in order to reduce the amount of machine set-up and tool-change time. However, because the width of the work surface and the jaws of prior art work holding vises cannot be expanded to accommodate wider work pieces or pluralities of work pieces, the user may be forced to inventory a number of various sized work holders. Such work holders may typically cost several hundred dollars and, thus, the average machine owner cannot afford to maintain an extensive inventory of such work holder devices. It may also be beneficial to be able to remove a work piece from the clamping apparatus for inspection or other purposes, and then return it to precisely the same position on the work holder. There is a continuing need for improved indexing and clamping systems for work pieces to be machined. In particular, there is a need for an improved system that will reliably hold a work piece, without slippage, in a manner that leaves most of the work piece surface accessible for machining operations. BRIEF SUMMARY OF THE INVENTION With parenthetical reference to the corresponding parts, portions or surfaces of the disclosed embodiment, merely for the purposes of illustration and not by way of limitation, the present invention provides a work holding device (10) for removably attaching a work piece (400) to a mounting surface (22) for machining. The work piece(400) may be provided with elongated wedge shaped channels (409) along two sides thereof and at least one indexing aperture (415) on its bottom surface (403). The work holding device (10) comprises a main body (13) having a proximal end (16), a distal end (19), and a mounting surface (22) disposed between the proximal and distal ends (16, 19). The body (13) includes a plurality of elongated, rounded polygonal openings (28) extending transversely there through and having a portion that intersects the mounting surface (22) thereby defining a plurality of open slots (43) in the mounting surface (22). The body (13) includes a tie bar (46) that extends across a portion of the open slot (43) and a plurality of locating pin apertures (49) between said open slots (43) that extend downward into the body (13). The locating pin