US3078535A - Wire clamp - Google Patents

Description

Feb. 26, 1963 w. E. HEDDERICH ETAL 3,

WIRE CLAMP 3 Sheets-Sheet 1 Filed June 15. 1960 m; M-zuqm (5' Weddericl 1 deal cflfiannev kgq Carl 3: 5 Carlson,

4QLOK YL6OY Ala-4 Lamb... CATTORNEIY/ aired Stats The present invention relates broadly to wire clamps and more specifically to clamps finding particular, but not necessarily exclusive use for holding steel wire or rods under tension during the manufacture of prestressed concrete beams.

In the production of prestressed concrete structural shapes such as beams, the concrete is provided with steel reinforcing members which are pretensioned while the beam is being cast and are held in this tensioned condition when the concrete has hardened. For the manufacture of prestressed concrete beams which are extremely large, such as the types now widely employed in bui1ding construction, continuous casting machines are employed which are capable of forming long lengths of beams. In apparatus of this character steel wire or rod is supplied from a continuous source such as a reel, and is fed through a tensioning and cut-off mechanism. During the casting of the beam, the pretensioned steel wire must be clamped in place on both sides of the beam. Various clamping mechanisms have been proposed for this purpose, although the results have not been entirely satisfactory.

The general object of the invention is to provide a new and improved wire clamp which is made from a small number of simply formed parts so as to be comparatively inexpensive, which is rugged and durable in service use and which is easily assembled and disassembled for cleaning.

A more detailed object is to make the clamp from simple sliding blocks which Wedge the wire between the jaws of the clamp and which are securely held in their operative positions even though they may be removed without the use of special tools.

Another object of the present invention is to facilitate the insertion of the reinforcing wire into the clamps so that the castin operation can be made substantially automatic and continuous and to provide a positive yet readily releasable grip on the wire which positively holds the wire when it is under tension.

Still another object of the invention is to facilitate the cleaning of the component parts of the wire clamp by utilizing planer surfaces in the construction thereof. A like object is to provide a wire clamp of the foregoing type'which has few movable parts thereby further reducing the possibility of fouling and faulty operation caused by collection of concrete thereon and further facilitating the cleaning of the clamp.

A further object of the invention is to provide a clamp having the foregoing characeristics in which the active clamp surfaces are protected against the entrance of concrete.

Other objects and advantages of the present invention will become apparent as the following description proceeds taken in connection with the accompanying drawings wherein:

FiGURE 1 is a perspective view of a concrete beam of the character produced by the mechanism with which the clamps embodying the present invention are employed.

PEG. 2 is afraginentary elevation view of a mechanism for tensioning reinforcing wire or rods in a concrete beam.

FIG. 3 is a section view taken substantially in the plane of line 3--3 of FIG. 2 and illustrating a plan view of clamps embodying the present invention.

FIG. 4 is a section view through a clamp embodying the present invention taken substantially in the plane of line 4-4 of FIG. 3 and showing a wire engaged by the clamp.

FIG. 5 is a view similar to FIG. 4 but illustrating the clamp in an open position.

FIGS. 6 and 7 are section views similar to FIG. 5 but showing a clamp in partial stages of disassem-bly.

FIG. 8 is a perspective view of the jaws of the clamp shown in FIGS. 3-7.

FlG. 9 is a section View taken substantially inthe plane of line 99 of FIG. 4 and illustrating the clamp operation.

FIG. 10 is a fragmentary section view similar to FIG 9 but showing the clamp in a fully released position.

FIG. 11 is a section view taken substantially in the plane of line 1111 of FIG. 10.

FIG. 12 is a perspective view of the mechanism for clamping the jaws shown in FIG. 8.

Concrete beams, such as the type shown at 10 in FIG. 1, are cast in a suitable apparatus, the details of which have not been shown. In general, typical apparatus includes a mechanism for supplying and pretensioning steel reinforcing members 11 which are embedded in the concrete beam. Because the concrete beams cast are usually quite long, the mechanism is supported on a gantry type carriage which straddles the beam casting mechanism and travels on rails in traversing the length of the beam. A portion of such a mechanism is shown in FIG. 2, the mechanism for engaging and gripping the free end of the reinforcing wires 11 being indicated generally at 14 and the wire supply, feed, cut-oif, and tensioning mechanism being indicated generally at 15. Some means, such as a feed screw 16 is usually provided for raising and'lowering the mechanisms 14, 15'. The reinforcin rod or wire 11 is fed from a supply source such as a reel (not shown) and is cut to length as it is used.

For securely gripping the reinforcing wires or rods, an improved clamping device is provided, a pair of such devices 2%, 21 being shown on opposite sides of the beam casting station, for use in conjunction with the wire tensioning mechanism in order to hold the pretensioned wires while the concrete beam is formed, which clamping devices are capable of holding the wires positively .and surely during the casting operation and can be readily released after the beam has set. The clamps 2t), 21, are mounted adjacent the casting station on suitable supports such as spaced vertical l-beam posts 22, 23., Generally, asecond pair of clamps 2d, 25 is provided at each station vertically displaced from the first pair so that a second set of reinforcing rods can be employed. This is important when, as shown in the drawings, the beams are cast with upper and lower pretensioned rods therein. Because the clamps 20, 21, 24 and 25 are identical, only one will be described in detail, it being understood that the description applies as well to the remaining clamps.

Each clamp comprises a body or clamp body 28 mountable on the support posts 22 (FIG. 3) and defining at each end a slot 29, 3d for receiving the clamping mechanism proper. By forming the clampbody 23 with a clamping mechanism at each end and mounting it at its center on the support post, two reinforcing wires can be tensioned simultaneously. In addition, because two pretensioned wires are gripped at one time, the structure is more rigid in that twisting of the support posts 22 is avoided. The clamp body 28 is secured to the support posts by suitable nut and bolt fasteners 31.

To grip the reinforcing wire 11, each clamp includes 3 two blocks 39 and 40 disposed side by side in the slot 29. Opposed surfaces 41 and 42 of the blocks are serrated or knurled to bite into and securely grip the wire whereby the blocks constitute the jaws of the clamp. The upper edges of the blocks are charnfered to provide sloping surfaces 44 which guide the Wire into the slot between the jaws and into position to be gripped.

Normally, the block 39 abuts against the wall 32 of the slot 29 as shown in FIG. 4 and the block 40 is forced laterally toward the block 39 by a wedge block 50. The latter also is disposed in the slot and acts between the wall 33 and the back of the block 40. For this purpose, the back of the block 40 is formed with an inclined or tapered surface 48 which bears against a mating surface 49 on the wedge 50 so that, as the wedge is moved longitudinally to the left as viewed in FIG. 8, the block 40-is shifted laterally toward the block 39.

Depending from the ends of the block 39 are flanges 45 which are spaced apart a distance generally equal to the width of the clamp body 23 so that they straddle the bottom wall 34 and prevent endwise shiftingof the block 39 while permitting the latter to slide sidewise. Similar flanges 46 depend from the ends of the block 40. The wedge 50 is longer than the blocks and also is formed-with depending flanges 52 which are spaced apart farther than the flanges 45 and 46 to permit limited endwise sliding of the wedge.

To prevent the blocks 39, 40 and 50 from being removed from the slot 29 during normal service use, shoulder members or flanges 35 and 36 project inwardly from the upper ends of the walls 32 and 33 respectively. The flange 35 is comparatively short and projects in closely over the block 39. The flange 36 fits closely over the wedge 50 and extends over substantially the full width of the latter. A third flange 51 projects in from the upper end of the wedge and over the block 40. Thus, the flange 35 holds the block 39 in the slot, the flange 36 retains the wedge 50 and the flange 51 holds the block 40. These three flanges, together with the flanges 45, 46 and 52, serve the added function of preventing concrete from splashing onto the various sliding surfaces and thereby prevent the clamp from fouling.

The wire clamping action of the wedge block 50 and jaws 39 and 40 is illustrated in FIGS. 9, and 11. The wedge block is sufficiently long so that it may be slid to one extreme and thereby release the jaws for separation suflicient to permit the insertion or removal of a reinforcing wire. shown in FIG. 9, the tapered surface 49 of the wedge block engages the corresponding surface 48 of the jaw 40 and thereby earns the jaws together into gripping engagement with the reinforcing wire 11. The serrated edges of the jaws bite into the wire and securely hold the same, even when the wire has been placed under considerable tension.

According to another aspect of the invention, the sizes of the flanges 35 and 36 are correlated in a novel manner with the sizes of the blocks 39, 40 and 50 so that the blocks may be removed from the clamp body 28 while normally being retained in the slot 29. For this purpose, the length of the flange 35 is such that, when the narrow end portion of the wedge 50 engages the block 40 and there is no wire between the jaws, the block 39 can be moved out from under the flange 35 as shown in FIG. 6 and lifted out of the slot 29. In any other position of the wedge, however, the flange 35 holds the block 39 in place as illustrated in FIG. 6. After the block 39 has been removed, the block 40 may he slid out from under the flange 51 and lifted out of the slot 29. Next, the wedge 50 is moved over to the position shown in FIG. 7 in which it is alined with the space between the flanges 35 and 36. This space is made slightly greater than the width of the wedge so that the latter may be lifted out of the slot. The reverse procedure is followed to assemble the clamp.

Upon movement to the other extreme, as i The cooperating tapered surfaces between the wedge block and the wedge jaw are clearly illustrated in FIG. 12. The slope of the tapered surfaces on the jaws is small so that an extremely powerful clamping force can thereby be obtained for a relatively small closing movement of the jaws. It will be appreciated that the clamping and jaw mechanism at each end of the clamp block 28 is a mirror image of the other. With this construction the movable wedge blocks are towards the center of the clamp block and remain always at a substantial fixed distance apart. With this position known the clamp is admirably suited for use with an automatic clamping mechanism which can be stopped in front of the body and actuate both sets of jaws at one time.

One illustrative mechanism for actuating and releasing the clamps is shown in FIG. 2. This mechanism comprises a hydraulic plunger mechanism 55 having a member 55 on one end thereof engageable with :1 depending flange 52 on the end of the wedge block 59. The plunger member 56 is preferably formed with a slot which slides beneath and straddles the flange 52. The clamp is constructed to be actuated to clamp the wire by moving the wedge block up as viewed in FIG. 9. In operation, the wire will be fed across the beam mold and gripped in clamps 20 at one side of the beam. A tension of the desired magnitude will be applied to the wire and clamps 21 engaged to hold the wire in place. The wire is then severed and the wire feeding and clamping mechanism will be moved to the next or to a lower station.

When the beam has been cast, the clamps can be readily released by engagement with the mechanism 55. This mechanism pushes on one end of the wedge block, preferably with a hammer-like blow, to release the clamping force and enable the wire to be withdrawn from the clamps.

It will be observed that a clamp constructed in accordance with the invention is comparatively inexpensive since all the parts are easily made and require no drilling, tapping or other similar operations. Moreover, the clamp is easy to assemble and disassemble but, at the same time, the parts are securely held in their operative positions during service use. In addition, the clamp when used with the manufacture of prestressed concrete beams is protected against fouling which might otherwise be caused by concrete splashings.

We claim as our invention:

1. A wire clamp comprising an elongated clamp body having a pair of opposed walls and a bottom surface defining an upwardly directed transverse slot in said clamp body, a first jaw member positioned in said slot against one of said walls and the slot bottom, said jaw member having a wire gripping surface and an upward- 1y chamfered surface extending therefrom, a pair of shoulders depending from said jaw member and slidably engaging the sides of said body, a second jaw member positioned in said slot adjacent said first jaw member and having on one side a wire gripping surface and a chamfered surface extending upwardly therefrom opposed to the corresponding surfaces on said first jaw member, a pair of shoulders depending from said second jaw member and slidably engaging the sides of said body, said second jaw member having on the opposite side a surface tapered with respect to the wire gripping surface, a wedge block member interposed between said second jaw member and the other slot wall and having a tapered surface corresponding to said tapered surface on said second jaw member, flanges projecting inwardly from each of said walls over the members adjacent thereto, and a flange on said wedge block member extending over said second jaw member, said flanges holding said jaw members and said block in said slot.

2. In a wire clamp, the combination of, a clamp body defining an upwardly directed slot having vertical trans verse walls, a pair of jaw members positioned in said slot adjacent one wall for gripping a wire and having end portions depending alongside said body, one of said jaws having a tapered wedge surface, a wedge block in said slot between said jaws and the other wall and having a wedge surface cooperable with said jaw wedge surface upon relative sliding movement with respect thereto to urge the jaws together into gripping engagement with the wire, shoulder members on said clamp body overhanging said walls, and a shoulder member on said wedge block overhanging said tapered surface, said shoulder members normally preventing removal of the jaw members and wedge block from said slot.

3. In a wire clamp, the combination of, a clamp body defining a slot, :1 pair of jaw members positioned in said slot for gripping a wire, one of said jaw members having a tapered wedge surface, a wedge block disposed in said slot adjacent said one jaw member and having a wedge surface cooperable with said jaw wedge surface upon relative sliding movement with respect thereto to urge the jaws together into gripping engagement with the wire, a first shoulder member on said clamp body overhanging said wedge block, a second shoulder member on said wedge block overhanging the adjacent one of said jaw members, and a third shoulder member on said body and overhanging the other of said jaw members, said shoulder members normally preventing said jaw members and said block from being removed from said slot.

4. in a wire clamp, the combination of, a clamp body defining an upwardly opening inverted T-shaped slot formed by a pair of vertical transverse walls and opposed members overhanging said walls, a pair of jaw members positioned in said slot with one of said jaws adjacent one of said walls and below one of said overhanging members, said jaw members having opposed gripping surfaces for holding a Wire and having end portions depending alongside said clamp body, the other of said jaw members having a tapered wedge surface, an L-shaped wedge block having one leg positioned in said slot between said other jaw and the opposite slot wall and beneath the other of said overhanging members, the other leg of said block overhanging said other jaw and said block having end portions depending alongside said clamp body, said wedge block further having a tapered wedge surface cooperable with said jaw wedge surface to urge the latter into gripping engagement with a wire upon relative transverse sliding movement between said wedge block and said jaw.

5. in a Wire clamp, the combination, a clamp body defining an upwardly opening inverted T-shaped slot formed by a pair of vertical transverse walls and opposed members overhanging said walls, a pair of jaw members positioned in said slot with a first one of said jaw members adjacent one of said walls and below a first one of said overhanging members, said jaws having gripping surfaces for holding a wire and having end portions depending alongside said clamp block, the second of said jaws having a tapered wedge surface, an L-shaped wedge block having one leg positioned in said slot between said second jaw and the opposite slot wall and beneath the second one of said overhanging members, the other leg of said block overhanging said one jaw and said block having end portions depending alongside said clamp body, said wedge block being narrower at one end to provide a tapered wedge surface cooperable with said jaw wedge surface to urge the latter into gripping engagement with a wire upon relative transverse sliding movement between said wedge block and said jaw, said first jaw being movable out from under said first overhanging member when the narrow end of said wedge block engages said second jaw.

6. In a wire clamp, the combination of, a clamp body having an upwardly opening slot defined by spaced vertical walls and a bottom surface, first and second jaws disposed in said slot with said first jaw against one of said walls, said jaws having opposed faces for gripping a wire, the back of said second jaw having a tapered wedge surface, a wedge disposed in said slot between said second jaw and the other of said walls and having narrow and wide ends to define a wedge surface cooperating with the wedge surface on said second jaw thereby to urge the second jaw toward the first jaw, a first flange projecting laterally from said one Wall to overlie said first jaw, a second flange projecting laterally from said other wall to overlie said wedge, and a third flange projecting laterally from said wedge to overlie said second jaw whereby said three flanges retain said jaws and said wedge in said slot.

7. in a wire clamp, the combination of, a clamp body having an upwardly opening slot defined by spaced vertical walls and a bottom surface, first and second jaw-s disposed in said slot with said first jaw against one of said walls, said jaws having opposed faces for gripping a wire, the back of said second jaw having a tapered wedge surface, a wedge disposed in said slot between said second jaw and the other of said walls and having narrow and wide ends to define a wedge surface cooperating with the wedge surface on said second jaw thereby to urge the second jaw toward the first jaw, a first flange projecting laterally from said one wall to overlie said first jaw, a second flange projecting laterally from said other wall to overl e said wedge, and a third flange projecting laterally from said wedge to overlie said second jaw whereby said three flanges retain said jaws and said wedge in said slot, said first jaw being movable in under the space between said first and second flanges when the narrow end of said wedge engages said second jaw.

S. In a wire clamp, the com ination of, a clamp body having an upwardly opening slot defined by spaced vertical walls and a bottom surface, first and second jaws disposed in said slot with said first jaw against one of said walls, said jaws having opposed faces for gripping a wire, the back of said second jaw having a tapered wedge surface, a wedge disposed in said slot between said second jaw and the other of said walls and having narrow and wide ends to define a wedge surface cooperating with the wedge surface on said second jaw thereby to urge the second jaw toward the first jaw, a first flange projecting laterally from said one wall to overlie said first jaw, a second flange projecting laterally from said other wall to overlie said wedge, and a third flange projecting laterally from said wedge to overlie said second ja-w whereby said three flanges retain said jaws and said wedge in said slot, said first and second flanges defining a space slightly larger than the overall width of said wedge and said first jaw being movable in under said space when the narrow end of said wedge engages said second jaw.

References {Zited in the file of this patent UNITED STATES PATENTS 769,878 Sturgis Sept. 13, 1904 1,079,646 Hansen Nov. 25, 1913 1,793,140 Steinmayer Feb. 17, 1931 2,204,979 Buchanan June 18, 1940 2,245,316 Amsler June 10, 1941 2,318,507 Martin May 4, 1943 2,548,712 Firmin Apr. 10, 1951 2,729,869 Huyser Jan. 10, 1956

Claims (1)

1. 3. IN A WIRE CLAMP, THE COMBINATION OF, A CLAMP BODY DEFINING A SLOT, A PAIR OF JAW MEMBERS POSITIONED IN SAID SLOT FOR GRIPPING A WIRE, ONE OF SAID JAW MEMBERS HAVING A TAPERED WEDGE SURFACE, A WEDGE BLOCK DISPOSED IN SAID SLOT ADJACENT SAID ONE JAW MEMBER AND HAVING A WEDGE SURFACE COOPERABLE WITH SAID JAW WEDGE SURFACE UPON RELATIVE SLIDING MOVEMENT WITH RESPECT THERETO TO URGE THE JAWS TOGETHER INTO GRIPPING ENGAGEMENT WITH THE WIRE, A FIRST SHOULDER MEMBER ON SAID CLAMP BODY OVERHANGING SAID WEDGE BLOCK, A SECOND SHOULDER MEMBER ON SAID WEDGE BLOCK OVERHANGING THE ADJACENT ONE OF SAID JAW MEMBERS, AND A THIRD SHOULDER MEMBER ON SAID BODY AND OVERHANGING THE OTHER OF SAID JAW MEMBERS, SAID SHOULDER MEMBERS NORMALLY PREVENTING SAID JAW MEMBERS AND SAID BLOCK FROM BEING REMOVED FROM SAID SLOT.

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