Bar clamp extension

Information

  • Patent Grant
  • 6530565
  • Patent Number
    6,530,565
  • Date Filed
    Wednesday, May 2, 2001
    23 years ago
  • Date Issued
    Tuesday, March 11, 2003
    21 years ago
  • Inventors
  • Examiners
    • Wilson; Lee
    Agents
    • Rosenberg; Daniel A.
    • Herink; Kent A.
    • Davis Brown Law Firm
Abstract
The present invention relates to an accessory for use with bar clamps, and more specifically, to a bar clamp attachment for extending a bar clamp to a plurality of working lengths. The bar clamp extension of the present invention generally comprises an extension bar and a coupler that releasably attaches the extension bar to a primary bar of a bar clamp.
Description




BACKGROUND OF THE INVENTION




1. Field of Invention




The present invention relates to an accessory for use with bar clamps, and more specifically, to a bar clamp attachment for extending a bar clamp to a plurality of working lengths.




2. Background of the Prior Art




Bar clamps are well known to craftsmen for use in holding a work piece in a fixed position. Typically, a bar clamp is used to hold a workpiece comprising multiple objects together for gluing, welding, or other purposes where it is advantageous to temporarily retain the workpiece in a fixed position. When encountering a clamping task, a craftsman will assess the size of a workpiece and select a clamp suitable for its retention. In cases calling for a bar clamp application, a craftsman selects a clamp having an appropriate length to embrace the subject work piece. However, to accomplish a variety of clamping tasks in association with a variety of projects, a craftsman is required to have multiple clamps of varying lengths.




One example of a prior art bar clamp is disclosed in U.S. Pat. No. 4,926,722 issued to Sorensen et al. The Sorensen et al. bar clamp comprises a movable jaw, a bar, and a fixed jaw. A disadvantage of the clamps known in the art, such as the Sorensen et al. bar clamp, is the finite length of the clamping bar. For example, while a movable jaw provides a variety of clamping positions along the length of the clamping bar, the finite length of the clamping bar limits the range of clamping positions available for each clamp. The finite length of each bar clamp requires a craftsman to purchase multiple clamps of varying lengths to accommodate various workpieces in association with accomplishing a variety of clamping tasks.




Therefore, a longstanding need remains for improvements in bar clamping devices. Such improvements would provide a craftsman the capability of utilizing a movable jaw component and a fixed jaw component in conjunction with a variety of bar lengths to achieve a modifiable bar clamp of varying lengths.




SUMMARY OF THE INVENTION




An improved bar clamp extension attachment for extending the working length of a bar of a bar clamp to a plurality of working lengths is described comprising an extension bar that has transverse dimensions matching those of the bar of the bar clamp. The bar clamp extension of the present invention will extend the working length of a typical bar clamp that has a moveable jaw and a fixed jaw in slidable and fixed engagement, respectively, with the bar of the bar clamp. A plurality of projections or pins extend transversely from a first and second end of the extension bar. The pins engage a coupler at the first end for releasably joining the extension bar to the bar of the bar clamp at the end which held the fixed jaw, and engage the fixed jaw at the second end. In operation, the fixed jaw is removed from the bar of the bar clamp and attached to the second end of the extension bar. The first and second ends of the extension bar are interchangeable.




A coupler includes a receiving member that is generally U-shaped in transverse cross-section wherein the web section and leg sections are sized to closely accommodate the end portions of the bar of the bar clamp and the extension bar. The end portions of the bar and extension bar are placed in the receiving member with their pins aligned with corresponding recesses in the receiving member. The coupler or clamp also includes a cover plate with recesses that is placed over the bar and extension bar end portions with the recesses aligned with the pins at the end portions of the bar and extension bar. A central throughbore in the receiving member and cover plate receives a nut and bolt combination for securing the coupler to the end portions of the bar and extension bar. The extension bars pins are comprised of metal, or alternatively, are spring pins, roll pins, or dowels.




After the extension bar is connected to the bar clamp, the extended clamp functions in the same manner as the bar clamp prior to its modification. In operation, a workpiece is clamped between a movable jaw and a fixed jaw. Sqeezing a handle on the clamp advances the movable jaw along the bar until a desired pressure is applied to the workpiece. To open the clamp, a trigger is squeezed and the movable jaw is pulled and released from the workpiece.




These and other aspects of the present invention will become apparent to those skilled in the art upon reference to the following specification, drawings, and claims.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a perspective view of a prior art clamp comprising a movable jaw, a bar, and a fixed jaw.





FIG. 2

is a perspective view of a bar clamp extension attachment in accordance with the teachings of the present invention with the prior art clamp of

FIG. 1

shown in phantom.





FIG. 3

is an exploded perspective view of the bar clamp extension attachment of

FIG. 2

with the prior art clamp of

FIG. 1

shown in phantom.





FIG. 4

is an enlarged perspective view of the cover plate and receiving member of the coupler.





FIG. 5

is an enlarged perspective view of the extension bar.





FIG. 6

is an enlarged top plan view of the extension bar and coupler.











DETAILED DESCRIPTION OF THE INVENTION




As shown in the drawings, and referring in particular to

FIG. 2

, numeral


10


designates the bar clamp extension assembly of the present invention. The assembly


10


generally comprises a coupler


12


that releasably attaches an extension bar


14


to a primary bar


20


of a pistol-grip bar clamp


16


(shown in phantom).




Referring now to

FIG. 1

, the pistol-grip bar clamp


16


includes a movable jaw


18


that is adjustable to a plurality of positions along primary bar


20


. A proximal end


22


and a distal end


24


define primary bar


20


. Typically, clamp


16


is configured with a fixed jaw


26


in secure engagement with the distal end


24


of primary bar


20


. Bar


20


includes a proximal pin


32


and a distal pin


34


(FIG.


3


), both of which extend transversely from bar


20


. Distal pin


34


releasably engages fixed jaw


26


. Sqeezing handle


30


advances jaw


18


along bar


20


. In operation, a workpiece (not shown) is clamped between jaws


18


,


26


, by advancing movable jaw


18


along bar


20


toward fixed jaw


26


until a desired pressure is applied to the workpiece. To open the clamp, trigger


28


is squeezed in the direction of proximal end


22


and jaw


18


is pulled in the direction of proximal end


22


.




As shown in

FIG. 3

, a proximal end


36


and a distal end


38


define extension bar


14


. Bar


14


further includes proximal pin


40


and distal pin


42


extending transversely from bar


14


. To attach extension bar


14


to clamp


16


, fixed jaw


26


is released from pin


34


and jaw


26


is slideably removed from end


24


of primary bar


20


and reattached to distal end


38


of extension bar


14


. Jaw


26


releasably engages pin


42


to retain its fixed position at the distal end of bar


14


. Also shown in

FIG. 3

, coupler


12


comprises a cover plate


46


and a receiving plate


44


having a cavity


48


. Plates


44


,


46


each include a plurality of pin recesses


50


,


50


′ and a central bore


52


,


52


′. Pin recesses


50


,


50


′ are provided for receiving pins


34


and


40


. To attach the extension bar


14


to the clamp


16


, the distal end


24


of primary bar


20


is aligned within the cavity


48


and receptively engaged by plate


44


and pin


34


is thereby receptively engaged by recesses


50


. The depth of cavity


48


is consistent with the width of bar


20


such that cavity


48


snugly receives bar


20


. Pin recesses


50


of plate


44


receives pin


34


and fixes the position of plate


44


relative to bar


20


. Likewise, cavity


48


snuggly receives the proximal end


36


of extension bar


14


and recesses


50


receive pin


40


. Pin recesses


50


of plate


44


receives pin


40


and fixes the position of plate


44


relative to bar


14


. The cover plate


46


and its recesses


50


′ and bore


52


′ are aligned with receiving plate


44


and pins


34


,


40


, such that central bores


52


,


52


′ are aligned for receiving a bolt


54


for securely engaging the sandwiched arrangement of plates


44


,


46


about the junction of bars


20


and


14


. Bolt


54


is received by central bore


52


,


52


′ and is threadably engaged by nut


56


to secure the placement of plates


44


,


46


in releasable engagement with bars


20


,


14


.




To accomplish the desired clamping effect, a user would have a series of extension bars


14


of varying lengths at his disposal. A modified pistol-grip bar clamp incorporating the bar clamp extension


10


easily accommodates a large workpiece by selecting an extension bar


14


having a length suitable for clamping the subject workpiece. A small workpiece is accommodated in much the same manner. The bar clamp extension


10


provides a user with a variety of clamping solutions without the need for individual clamps of varying lengths. Rather, a user merely selects an extension bar of a length suitable to accommodate a workpiece and modifies the pistol-grip bar clamp accordingly.




In a preferred embodiment, coupler


12


is non-orientation dependent, meaning it works equally as well in connecting bars


14


and


20


when the position of the plates


44


,


46


relative to the bars


14


,


20


is rotated by 180° about an axis formed by the bolt path


58


as shown in FIG.


3


. Furthermore, the non-orientation dependent positions of receiving plate


44


and cover plate


46


can be reversed from the embodiment as shown in FIG.


3


.




Also in a preferred embodiment, extension bar


14


is constructed of ¼ inch by ¾ inch surface hardened steel. Pins


40


,


42


are ¼ inch in diameter and ⅝ inch in length. Furthermore, pins


40


,


42


are spring pins, or alternatively, roll pins, or alternatively dowels pressed into bar


14


. Plates


44


,


46


are constructed of aluminum or steel and are machined to a configuration to receive and fit bar


14


. Bolt


54


is preferably


¼ inch by


1 inch having 20 coarse thread per inch and is threadably received by plate


46


. Nut


56


is


¼ inch in diameter having


20 coarse thread per inch. Alternatively, fasteners of other types well known in the art can be substituted for the nut/bolt fastener arrangement. For example, a hand knob having a female


¼ inch in diameter threaded receiving member,


20 coarse thread per inch, could be substituted for nut


56


.




The foregoing description and drawings comprise illustrative embodiments of the present inventions. The foregoing embodiments and the methods described herein may vary based on the ability, experience, and preference of those skilled in the art. The foregoing description and drawings merely explain and illustrate the invention, and the invention is not limited thereto, except insofar as the claims are so limited. Those skilled in the art who have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention.



Claims
  • 1. A bar clamp extension apparatus for extending the working length of a bar clamp, the bar clamp including a primary bar and a fixed jaw that is releasably mounted on the distal end of the primary bar, wherein the fixed jaw is removed from the primary bar, the extension apparatus is attached to the distal end of the primary bar, and the fixed jaw is attached to the distal end of the extension apparatus, the extension apparatus comprising:a. an extension bar having a proximal end section and a distal end section; b. a pin projecting from either side of the distal end section of the extension bar for releasably attaching the fixed jaw of the bar clamp; c. a pin projecting from either side of the proximal end section of the extension bar; and d. a coupler associated with the proximal end section of the extension bar for releasably attaching the proximal end section of the extension bar to the distal end of the primary bar in longitudinal alignment therewith; the coupler comprising: i. a pair of plates positioned in contact engagement on either side of the proximal end of the extension bar and of the distal end of the longitudinally aligned primary bar; ii. recesses in said plates for capturing the pin projecting from either side of the proximal end of the extension bar; and iii. means interconnecting the pair of plates for applying clamping pressure to hold the pair of plates in contact engagement with the primary bar and the extension bar.
  • 2. Apparatus as defined in claim 1, wherein the means for interconnecting the pair of plates comprises a central bore through the pair of plates in receptive engagement with a fastener assembly.
  • 3. Apparatus as defined in claim 2, wherein the fastener is a nut and bolt arrangement.
  • 4. Apparatus as defined in claim 3, wherein the nut comprises a hand knob.
  • 5. Apparatus as defined in claim 1, wherein the extension bar is reversible.
  • 6. A bar clamp and bar clamp extension combination for extending the working length of the bar clamp, the combination comprising:a primary bar with a distal end section and a proximate end section, with a pin projecting from either side of the distal end of the primary bar; a moveable jaw movably attached to the proximate end section of the primary bar, having a squeezable handle for moving the jaw along the primary bar; a fixed jaw; an extension bar having a proximal end section and a distal end section; a pin projecting from either side of the distal end section of the extension bar for releasably attaching the fixed jaw; a pin projecting from either side of the proximal end section of the extension bar; and a coupler associated with the proximal end section of the extension bar and the distal end of the primary bar for releasably attaching the extension bar to the primary bar in longitudinal alignment therewith; the coupler comprising: a pair of plates positioned in contact engagement on either side of the proximal end of the extension bar and of the distal end of the longitudinally aligned primary bar; recesses in said plates for capturing the pin projecting from either side of the proximal end of the extension bar and the pin projecting from either side of the distal end of the primary bar; and means interconnecting the pair of plates for applying clamping pressure to hold the pair of plates in contact engagement with the primary bar and the extension bar.
  • 7. Apparatus as defined in claim 6, wherein the interconnecting means for applying clamping pressure comprises a central bore through the pair of plates in receptive engagement with a nut and bolt arrangement.
  • 8. Apparatus as defined in claim 7, wherein the nut comprises a hand knob.
US Referenced Citations (10)
Number Name Date Kind
1484794 Moses Feb 1924 A
1583611 Seely May 1926 A
4649679 Arens Mar 1987 A
4735389 Graham Apr 1988 A
4926722 Sorensen et al. May 1990 A
5149149 Wu Sep 1992 A
6029964 Bohl Feb 2000 A
6089556 Whiteford Jul 2000 A
6302386 Fuller et al. Oct 2001 B1
6386530 Marks May 2002 B1