WORKPIECE CLAMP

• US 3,561,748 A
• Filed: 10/18/1968
• Issued: 02/09/1971
• Est. Priority Date: 10/18/1968
• Status: Expired due to Term

• Current Assignee: Schefers, Corby J.
• Original Assignee: Schefers, Corby J.
• Inventors: Schefers, Corby J.
• Application Number:
  US04/768,782
• Time in Patent Office: 844 Days
• US Class Current: 269/8
• CPC Class Codes: B23Q 2703/00 Work clamping
• CPC Class Codes: B23Q 3/00 Devices holding, supporting, or positioning work or tools, of a kind normally removable from the machine work-tables or other parts, e.g. faceplates, normally not incorporating means for securing work B23Q1/00; automatic position control B23Q15/00 ; food cutting boards A47J47/00; workpiece support for dies B21D37/02; rotary tool heads for turning-machines B23B3/24, B23B3/26; non-driven tool holders B23B29/00; general features of turrets B23B29/24 ; drawbars in spindles B23B31/261; for electrical discharge machining B23H11/003; for welding B23K37/04; means for securing grinding wheels B24B45/00; mountings for abrasive wheels B24D5/16; tools or bench devices for fastening, connecting, disengaging or holding B25B ; chucks for percussive tools B25D17/084; work benches for manual work B25H1/00; devices for securing circular saw blades B27B5/32; for assembling or manufacturing aircrafts B64F5/10; for holding semiconductors or wafers H01L21/67; devices for holding circuit boards H05K13/0061
• CPC Class Codes: B23Q 3/154 Stationary devices
• CPC Class Codes: B25B 11/002 Magnetic work holders

Abstract

A versatile workpiece clamp having many uses with and without magnetic chucks. The clamp comprises a strip of rigid material having closely-spaced slightly-flexible fingers acutely inclined to one lateral edge with their exposed ends lying in a common plane and adapted to be held in firm contact with a workpiece backed by a suitable stop. A work force applied to the exposed surface of the workpiece and generally toward the fingers acts to flex the fingers into firmer gripping contact with the workpiece without risk of injury thereto. The clamp can be used alone or in combination with a second clamp. If made of magnetic material the clamp can be used with a magnetic chuck and employed to clamp workpieces made of a wide variety of nonmagnetic materials.

Claims

1. A workpiece clamp for use in holding a workpiece jammed against a fixed backup while work is being performed on the workpiece, said clamp comprising a single wide strip of homogeneous rigid material of rectangular cross section having a row of long fingers lying at an acute angle to one edge of said strip and integral with one another distantly from the free ends thereof, said clamp being flat and inflexible transversely of the thickness thereof the free ends of said fingers being flat and lying in a common plane normal to the wide face surfaces of said strip, the free ends of said slender fingers being frictionally engageable with a workpiece and deflected in the plane of the strip and in a direction to increase the clamping pressure against the workpiece as an attempt is made to shift the workpiece in one direction thereby to hold a workpiece supported against a backup and effective to anchor the workpiece against movement by a working force tending to increase the frictional engagement of the ends of the fingers with the workpiece.

2. A workpiece clamp as defined in claim 1 characterized in that said clamp strip is formed of magnetic material.

3. A workpiece clamp as defined in claim 1 characterized in that adjacent ones of said fingers are separated from one another by a narrow intervening slot each opening into an enlargement at its inner end effective to decrease the width of the fingers at their inner root ends to a width less than the width of the main body of said fingers thereby enabling the fingers to flex at the root ends thereof rather than along the length of said fingers.

4. A workpiece clamp adapted to be used with a magnetic chuck to hold a workpiece anchored while being worked upon, said clamp comprising a single elongated rigid planar strip of magnetic material inflexible transversely of its thickness and having long slots extending inwardly at an acute angle from one lateral edge thereof to provide a multiplicity of long relatively inflexible fingers rigidly interconnected along the other lateral edge of said strip, the free end edges of said fingers lying in a common plane normal to the face of said strip and effective to grip the adjacent surface of a workpiece with increasing frictional pressure as a working force is applied to a workpiece in a direction tending to flex said fingers solely in the plane of said clamp and in a direction to increase the width of said strip whereby an increasing work force automatically increases the clamping force applied to the workpiece.

5. An article of manufacture comprising a single elongated rigid planar strip of rectangular shape in cross section, said strip being inflexible transversely of its thickness and having a series of deep closely-spaced slots extending through one lateral edge of said strip to points adjacent the other lateral edge and lying at an acute angle to said one edge, saiD slots dividing said strip into a plurality of long relatively nonflexible fingers having their free end faces lying in a common plane generally normal to the face of said strip, thereby to provide a powerful clamping device adapted to be anchored immovably to a support for a workpiece with the free end faces of said fingers positioned to bear against a workpiece and being effective to hold a workpiece firmly when a working force is applied to the workpiece tending to flex said fingers in a direction opposite to the slope thereof and so as to increase the planar width of said clamping strip.

6. That method of utilizing a magnetic chucking device to clamp a nonmagnetic workpiece to the bed of a machine tool while work is being performed thereon which method comprises:

placing the nonmagnetic workpiece against a fixed backup of a machine tool bed and adjacent a magnetic chucking device secured to the machine tool, positioning the free end faces of long relatively nonflexible fingers against the workpiece on the side thereof remote from said backup and the ends of which fingers are integrally attached to and form a part of a long planar strip of homogeneous rigid magnetic material slotted at an acute angle from one lateral edge thereof, energizing the chucking device to clamp the workpiece after noting that the face of said strip has been placed against the chucking device such that the free ends of said fingers project generally oppositely to the work force to be applied to the workpiece, and utilizing a working force applied to the workpiece in a direction to increase the frictional engagement of the finger ends of the fingers and to flex the fingers about their root ends in the plane of said planar strip and toward the fixed backup for the workpiece thereby to anchor the workpiece against movement.

7. That method of holding a smooth-surfaced nonmagnetic workpiece to the bed of a tool while being worked upon without risk of damage to the smooth surfaces subjected to clamping pressure which method comprises:

placing one edge of the workpiece against fixed backup means, placing one flat face of a single planar multislotted clamping plate flush against a supporting surface for the workpiece with one lateral edge against an edge of the workpiece on the opposite side thereof from said fixed backup, and which clamping plate has a multiplicity of long relatively nonflexible fingers lying at acute angles to the plate edge, securing said clamping plate against movement, and activating said fingers to clamp the workpiece by applying the working force to the workpiece in a direction tending to flex said fingers in the plane of said clamping plate about their respective root ends in an arc toward said workpiece and the fixed backup therefor thereby to jam the workpiece more firmly between the free ends of said fingers and said backup.

8. That method defined in claim 7 characterized in the steps of utilizing magnetic material for said clamping plate, and energizing a magnetic chuck device to hold the free ends of the fingers of said clamping plate in frictional engagement with the edge of the workpiece remote from said fixed backup.

9. That method of chucking the finished edges of a workpiece without risk of damage thereto while performing work thereon which method comprises:

resting the workpiece on a support surface, applying the flat-surfaced free ends of two sets of coplanar closely spaced long relatively nonflexible fingers against the opposed edges of said workpiece with the free ends of the fingers parallel to one another and the longitudinal axes of the fingers of said two sets lying in a common plane parallel to the support surface for the workpiece and converging toward one another, clamping the remote ends of said sets of fingers against movement and with their adjacent free ends in light pressure contact with the edges of a workpiece, and activating said fingers to clamp the workpiece by applying a work force to the workpiece in a direction to flex the free ends of said Two sets of fingers about their respective root ends and into tighter pressure and frictional contact with the edges of the workpiece.