FIELD OF THE INVENTION

The present invention relates generally to clamps for holding workpieces and,

more particularly, to edge clamps and spring clamps.

BACKGROUND OF THE INVENTION

Three-way C-clamps are commonly used for applying clamping forces to

workpieces in three directions. The clamps are generally used as edge clamps for

clamping workpieces together. Three-way C-clamps generally comprise a C-shaped

frame and three clamping screws, each in threaded engagement with apertures in the frame. Clamping is accomplished by separately rotating the clamping screws into engagement with the upper and lower surfaces of one ofthe workpieces and with a

side surface of another workpiece. Using the three-way C-clamp is a cumbersome

and time consuming process because the user must adjust each ofthe three clamping

screws separately. Additionally, use of both hands ofthe user is normally required: one to hold the C-frame and the other to adjust the clamping screws. A need thus

exists for a three-way clamp that can be quickly and easily applied to workpieces

using one hand.

SUMMARY OF THE INVENTION

A three-way spring clamp is provided that is useable as an edge clamp for

applying clamping forces to workpieces in three directions. The clamp includes two

lever arms, each having a jaw end and a handle end. The lever arms are pivotally connected to each other at a pivot point located between the jaw ends and the handle

ends such that the lever arms can be moved between a closed gripping position in

which the jaw ends are proximate to each other, and an opened position in which the

jaw ends are spaced apart. A coil spring is provided for biasing the lever arms toward the closed gripping position. A spring engagement member is mounted between the

lever arms. The engagement member includes a central body portion engageable with

a surface of an article to be clamped. The body portion is positioned between the

pivot point and the jaw ends and, in accordance with one embodiment, has a generally

concave configuration from the perspective ofthe pivot point when the lever arms are

in the closed gripping position. The engagement member provides spring pressure in

a direction generally perpendicular to the direction of clamping forces applied by the

jaws ofthe clamp, making the clamp suitable for use as a three-way edge clamp.

In accordance with another embodiment ofthe invention, a folding hinge-type

engagement member is provided in place ofthe spring engagement member.

The three-way spring clamp in accordance with the invention can be quickly

and easily applied to a workpiece by a user using only one hand.

The spring clamp can be easily and inexpensively manufactured. No retooling

would be necessary since presently available spring clamps can be retrofitted with

engagement members to form the three-way clamps.

Since many edge clamping operations require use ofa clamp positioned

approximately every 4-6 inches apart on the workpiece, large quantities of clamps are

usually required. Thus, use of clamps in accordance with the invention would result

in substantial savings of time and money.

Furthermore, the addition ofthe engagement member will not substantially

interfere with the original use of presently available spring clamps in that clamps in

accordance with the invention can be used either as three-way edge clamps or as basic

two-way squeeze clamps.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a side view of a three-way C-clamp in accordance with the prior

art.

Figure 2 is a perspective view of a spring clamp in accordance with the prior

art.

Figure 3 is a perspective view ofa three-way spring clamp in accordance with

one embodiment ofthe present invention.

Figure 4 is a side view ofthe Figure 3 clamp shown in a closed gripping

position.

Figure 5 is a side view ofthe Figure 3 clamp shown in an opened position.

Figure 6 is a side view ofthe Figure 3 clamp shown clamped about a

workpiece.

Figure 7 is a side view of a three-way spring clamp in accordance with a

preferred embodiment ofthe invention.

Figure 8 is a side view of a three-way spring clamp in accordance with yet another embodiment ofthe invention.

Figure 9 is a side view of a three-way spring clamp in accordance with yet

another embodiment of the invention.

Like reference numerals denote like parts in the drawings.

DETAILED DESCRIPTION OF VARIOUS ILLUSTRATIVE EMBODIMENTS

A prior art three-way C-clamp 10 used for applying clamping forces in three

directions is illustrated in Figure 1. The three-way C-clamp 10 comprises a C-shaped

frame 12 and three clamping screws 14, each in threaded engagement with apertures

in the frame 12. As shown in Figure 1, the three-way C-clamp 10 is used, for

example, as an edge clamp for clamping a first workpiece, a strip of material 16, to a

second larger workpiece 18. Clamping is accomplished by separately rotating each of

the clamping screws 14 into engagement with the upper and lower surfaces ofthe

workpiece 18 and with a side surface ofthe strip 16. Using the three-way C-clamp 10

is a cumbersome and time consuming process because the user must adjust each ofthe

three clamping screws 14 separately. Additionally, the user must use both hands to

operate the clamp, one to hold the C-frame 12 and the other to adjust the clamping

screws 14.

Figure 2 illustrates a prior art spring clamp 30, sometimes called a "squeeze clamp," which is a light duty clamp that works much like a spring loaded clothespin

for applying pressure to two sides of a workpiece. Such clamps can be easily and

quickly applied to workpieces because they require no adjustment. Also, they can be

used with only one hand, freeing the other hand to perform other tasks like, for

example, holding the workpiece. Spring clamps are also inexpensive and available in

several sizes, most commonly in 2", 3", and 4" sizes.

As shown in Figure 2, the spring clamp 30 includes first and second lever arms

32 pivotally coupled to a pivot pin 34 defining a pivot point. The lever arms 32 each include a jaw end 36 and an opposite handle end 38. The central portion of each lever

arm 32 includes a bracket extension 40 having a pivot pin receiving aperture 42. The

brackets 40 are positioned to overlap each other such that the pivot pin receiving

apertures 42 are aligned.

The clamp 30 also includes force applying means comprising a biasing helical

coil spring 44 that includes a coiled portion forming a tube 46 (shown in phantom in

Figure 2) and end extensions 48 projecting from the tube 46. The tube 46 is disposed

between the brackets 40 so as to align the interior ofthe tube 46 with the apertures 42

in the brackets 40. The pivot pin 34 extends between the apertures 42 and through the

interior ofthe tube 46. The end extensions 48 ofthe spring 44 project generally away

from the jaw ends 36 and engage the handle ends 38. The tension in the spring 44

biases the handle ends 38 apart and urges the jaw ends 36 toward each other in the

closed gripping position illustrated in Figure 2.

Elastomeric covers 50 can be placed over the jaw and handle ends 36, 38 of

the lever arms 32. The elastomeric covers 50 are provided to furnish a comfortable

grip, to electrically insulate the handle ends, and to prevent the jaw ends from marring

any article held therein.

A three-way spring clamp 100, useable as an edge clamp in accordance with

one embodiment ofthe present invention, is shown in Figures 3-6. The spring clamp

100 is similar to the clamp 30 of Figure 2, but includes an additional resilient

engagement member comprising a flat or plate spring 102 mounted in the clamp 100

between the lever arms 32 to provide an additional third clamping surface.

The flat spring 102 comprises a resilient elongated member having a generally

flat configuration when unstressed. As shown in Figures 4 and 5, the flat spring

comprises central body portion 104 and end portions 106 on opposite sides ofthe

body 104. As with the jaw and handle ends 36, 38 ofthe lever arms 32, the body

portion 104 ofthe flat spring 102 can be covered with an elastomeric cover to inhibit

the marring of an article held by the clamp 100.

A three-way spring clamp 100 in accordance with the first embodiment is

formed by fitting the flat spring 102 in a spring clamp ofthe type shown in Figure 2.

The spring 102 is inserted between the lever arms 32 such that the ends 106 ofthe

spring 102 are pressed against the front edge 108 of each bracket extension 40. In

Figures 3 and 4, the spring clamp 100 is shown in a closed gripping position wherein

the jaw ends 36 are in contact with each other. The flat spring 102, which has a length

greater than the distance between the lever arms 32 at the brackets 40, is compressed

by forces applied by the coil spring 44 and assumes a substantially curved

configuration with the central body portion 104 ofthe spring 102 projecting towards

the jaw ends 36 ofthe clamp 100.

When the handles 38 ofthe spring clamp 100 are pressed together as shown in

Figure 5, the clamp 100 moves to an opened position in which the jaws 36 are moved

apart from each other. The flat spring 102 consequently resiliently changes from its

distinct curved configuration of Figures 3 and 4 to a more flattened configuration as

compression thereof by the lever arms 32 is reduced. As the flat spring 102 assumes a

flatter configuration, the central body portion 104 ofthe spring moves away from the

jaw ends 36 ofthe clamp and towards the pivot point 34.

Once opened, the spring clamp 100 can be applied to a workpieces 110, 112 as

shown in Figure 6. The workpiece 110 comprises, for example, a large flat object

such as a counter top. The clamp 100 can be used for example to urge the second

workpiece, a strip of material 112, against an edge ofthe workpiece 110 to assist in,

for instance, gluing the strip 112 to the workpiece 110.

The jaws 36 ofthe spring clamp 100 in the opened position are positioned

around the strip 112 and the edge ofthe workpiece 110. The handles 38 are then

gradually released and the jaws 36 consequently brought into engagement with the

upper and lower surfaces ofthe workpiece 110. At the same time, the spring plate

104 moves from a flattened configuration toward a more curved configuration under

compression from the lever arms 32. In the process, the central body 104 ofthe

spring 102 moves away from the pivot point 34 towards a side surface ofthe strip

112. The body portion 104 is thereby brought into engagement with the strip 112 to

urge the strip 112 against the workpiece 110 with resilient spring force.

Thus, a user can, with one hand, easily apply the spring clamp 100 to

workpieces to provide three-way clamping pressure, making the clamp suitable for

use as an edge clamp.

Flat springs can be retained in spring clamps in accordance with the invention

by various retention means. Figure 7 illustrates a three-way spring clamp 200 in

accordance with the invention having a preferred modified flat spring 202, the ends

204 of which are secured by angled projections 206 in the lever arms 32. Flat springs

may also be retained in lever arms with the use of various types of fasteners (not

shown) including, for example, rivets. Additionally, holes (not shown) may be

stamped into flat springs such that the springs can be snapped in place over

projections in the lever arms.

In addition, as shown in the three-way spring clamp 300 of Figure 8, a spring

engagement member 302 can be provided having end portions 304 having an

undulated or wavelike shape. The end portions 304 are resiliently deformable and

designed to snap into place against the lever arms 32.

Thus, in accordance with the present invention, a prior art spring clamp can be

easily transformed into a three-way clamp with the insertion therein ofa spring

engagement member. The engagement member provides spring pressure in a

direction generally perpendicular to the direction of clamping forces applied by the

jaws ofthe clamp, towards the jaw ends, making the clamp suitable for use as a three-

way edge clamp.

Also, it should be noted that the addition ofthe engagement spring will not

substantially interfere with the original use of presently available spring clamps in that

the clamps in accordance with the invention can be used either as three-way edge

clamps or as basic two-way squeeze clamps.

Figure 9 illustrates a three-way spring clamp 400 in accordance with yet

another embodiment ofthe invention. In this embodiment, the engagement springs of

the earlier embodiment are replaced by a collapsible member 402 comprising a

folding hinge-type mechanism. The collapsible member comprises two outer bars 404

and a center bar 406. The forward ends ofthe outer bars are each pivotally connected

to an opposite end ofthe center bar. The rear ends ofthe outer bars are pivotally

connected by means of a standard pivot pin connection to the lever arms 32. In Figure 9, the hinge-type mechanism 402 is shown in a generally collapsed

configuration. As the jaws 36 ofthe clamp 400 are opened, the mechanism 402

moves toward a straighter configuration. When clamped about a workpiece, the

center bar 406 engages a side surface ofthe workpiece, providing three-way clamping

action. While not shown, it should be understood that collapsible mechanisms of

various configurations can be used to provide the third engagement surface ofthe

clamp.

The present invention has been described in the foregoing specification with

respect to specific embodiments. These embodiments serve as examples to illustrate

the invention rather than to limit its scope. Modifications may be made thereto

without departing from the broader teachings ofthe invention.