US3728836A - Concrete form tie and rebar chair - Google Patents

Abstract

This invention relates to an improved twisted wire concrete form tie characterized by a lower single-wire strand joined to an upper double-wire twisted section by a pair of return bends at opposite ends, all of which cooperate with one another to define an elongate endless loop. The portions of the length of wire that are laid side-by-side and twisted together to form the twisted section terminate in free ends that are bent to form upstanding stops with upwardly opening generally U-shaped rebar saddles on the inside thereof. The section of the return bend projecting outwardly beyond the adjacent stop is slightly longer on one end than the other.

Description

United States Patent Gates 11 3,728,836 Apr. 24, 1973 CONCRETE FORM TIE AND REBA CHAIR [75] Inventor: Robert C. Gates, Lakewood, C010.

[73] Assignee: Gates & Sons, Inc., Denver, C010.

[22] Filed: Dec. 27, 1971 21 Appl. No.: 211,994

[52] US. Cl. ..52/687, 52/712, 249/215 [51] Int. Cl. ..E04c 5/16, E04g 17/06 [58] Field of Search..52/687689,'7l2-715; 249/215 [56] References Cited UNITED STATES PATENTS 1,692,166 11/1928 Gates ..249/2l5 FOREIGN PATENTS OR APPLICATIONS 785,849 11/1957 Great Britain ..249/2l5 Primary Examiner-John E. Murtagh Assistant Examiner-James L. Ridgill, Jr. Att0rneyAnderson, Spangler & Wymore [57] ABSTRACT This invention relates to an improved twisted wire concrete form tie characterized by a lower single-wire strand joined to an upper double-wire twisted section by a pair of return bends at opposite ends, all of which cooperate with one another to define an elongate endless loop. The portions of the length of wire that are laid side-by-side and twisted together to form the twisted section terminate in free ends that are bent to form upstanding stops with upwardly opening generally U-shaped rebar saddles on the inside thereof. The section of the return bend projecting outwardly beyond the adjacent stop is slightly longer on one end than the other.

6 Claims, 2 Drawing Figures Patented April 24, 1973 wmvm n J L\N\ NW 1 \swl m w w\ w m L INVENTOR ROBERT C GATES AJ' IORNEYS &

CONCRETE FORM TIE AND REBAR CHAIR Twisted wire concrete form ties of one type or another have been used for many years in the construction industry to hold two upstanding form panels or walls in fixed-spaced parallel relation while concrete was poured therebetween. Probably the most popular and successful of these twisted wire ties is one that has been in widespread use for over twenty years and is characterized by a three-wire twisted center section terminating at opposite ends in elongate generally teardrop-shaped loops having vertically disposed stops projecting therethrough formed by the free ends of the wire. Notwithstanding the widespread acceptance of this prior art twisted-wire tie, it has certain limitations from both the standpoints of manufacture and use that could stand some improvement.

For instance, in the manufacture of this tie, the loop at one end is held while the one at the other end is gripped and turned to form the twisted section therebetween. The resulting three-wire cable contains a maximum of only about four complete turns in a inch tie while a tie made in accordance with the teaching of the present invention of the same length with wire of the same gauge can accommodate a cable having twice as many twists. Also, the prior art tie must be overtwisted a precise amount so that the residual tension left in the wire when the loops are released will return them to essentially coplanar relation. The instant tie, on the other hand, has its cable portion formed by holding opposite ends of the overlapping strands and twisting from the middle outwardly thus doing away completely with any alignment problems as it makes no difference how much the center section unwinds upon being released.

The teardrop-shaped loops of the conventional twisted wire tie cause certain problems in that they allow the tie to tilt down so steeply when inserted into the tie slot in the form panel that it can fall out before the tie rod can be passed therethrough. Also, once the rod is in place its weight is such that the tie will tilt up above horizontal and become difficult to align with the opposite slot when doubling up the forms. The present tie presents no such problems because the parallel legs extending out from its return bends prevent excessive downward tilt. More significant, however, is the manner in which the legs adjoining the shorter of the two return bends cooperate therewith and with the stop or spreader and tie rod when the latter is' in place to hold the tie in horizontal aligned relation to the opposite tie slot.

Not only the prior art twisted wire ties but other types of form ties as well make no provision for retaining the steel reinforcing rod known as rebar in fixed spaced relation inside the form walls, yet, the building codes in most urban areas require that it be located a certain distance inside the face of the poured concrete wall in order to provide the maximum reinforcement for which it was inserted in the first place. In order to maintain the rebar in such a position, the rods are tied to every third tie or so in a horizontal row thereof with short lengths of wire. This operation usually requires two workmen and, all too often, the ties thus tied will not line up properly with the opposite form tie slot when the forms are doubled up. When this occurs, the ties must be untied from the rebar and retied so as to register with the tie slots. Obviously, all the rebar except, perhaps, the top row must be tied off before the forms are doubled up as there is no room to work therebetween.

The instant tie overcomes this shortcoming of the prior art ties by providing upwardly opening U-shaped saddles transversely aligned in each horizontal row of ties to receive two lengths of rebar and maintain them in fixed-spaced parallel relation to one another and to the form walls bounding same. One man can easily place the rebar in place and permanent fastenings need only be made at opposite extremities of the rod where it is wired to two ties some twenty feet apart.

A certain other, but nonetheless important, feature of the form tie comprising the subject matter of the present invention is the ease with which the forms can be doubled up using same. When the short end of the tie is inserted through the slot in the outside form wall with its stop or spreader up snug against the inside of the latter, it will slope down just far enough to open the reverse bend so that the tie rod or pipe can be slipped easily therethrough. With the weight of the pipe push ing down on that portion of the loop projecting on to the exterior of the outside panel, the remaining portion on the inside swing up into more or less level position using the inside stop as a fulcrum. Once the tie is level, the pipe is pulled snug against the outside of the form wall with the stop engaging the inside thereof.

Now, with the ties in more or less horizontal position, the inside form wall is easy to double up. The portion of the loop projecting inwardly beyond the inside form wall is easy to double up. The portion of the loop projecting inwardly beyond the inside form wall is, in accordance with the teaching of the instant invention, somewhat longer than the corresponding portion projecting beyond the outside wall so as to easily receive the inside tie rod or pipe. For this reason, the ties have an outside end and an inside end, at least one of whic should be clearly identified.

One other feature is worthy of particular mention, namely, the parallel relation of the upper and lower strands of the loop which facilitates their being snipped flush with the form panels during the stripping operation. The twisted wire ties with the narrowing teardropshaped loops are much more difficult to snip because the wires adjacent the twisted central cable portion lie somewhat hidden behind the rod.

It is, therefore, the principal object of the present invention to provide a novel and improved twisted wire concrete form tie.

A second objective of the invention herein disclosed and claimed is to provide a form tie with a self-leveling feature once a tie rod or pipe is passed therethrough.

Another object of the within described invention is to provide a form tie with two-wire twisted cable sections having more turns and, therefore, more tensile strength than a comparable one with three-wire twisted cable.

Still another objective is the provision of a concrete form tie having longitudinally spaced upwardly opening U-shaped saddles adapted to receive and maintain the rebar in proper fixed position.

An additional objective is to provide a form tie with the spreader stops spaced different distances from their adjacent return-bent ends so as to facilitate doubling up of the forms.

Further objects of the invention forming the subject matter hereof are to provide a wire concrete form tie that is strong, lightweight, easy to use, reliable, compact, versatile, simple to manufacture, inexpensive and even decorative in appearance.

Other objects will be in part apparent and in part pointed out specifically hereinafter in connection with the description of the drawings that follows, and in which:

FIG. 1 is a horizontal sectional view showing the form tie of the present invention held in level position against the outside form wall by a hollow tie rod, the location of one of the rebars having been shown in broken lines; and,

FIG. 2 is a vertical section showing the same elements as in FIG. 1 and, in addition, the inside form panel in position to be doubled up in full lines as well in fully assembled relation in broken lines. Referring next to the drawings for a detailed description of the present invention, reference numeral has been chosen to designate the form tie of the present invention in its entirety while numeral 12 identifies the form wall panels and numeral 14 the tie rods. In the particular form shown, rods 14 are pipes rather than solid rods, the former having the advantage of being somewhat lighter than the latter although either can be used with tie 10. Thus, as used herein, the term tie rod is intended to encompass both solid and hollow rods or pipe.

Form panels 12 are, likewise, conventional, those illustrated being vertically slotted as shown at 16. Ordinarily, these paenls will be fabricated from one-half to three-fourths inch plywood although ordinary sheathing could be used if necessary. The tie slots 16 are sized to easily pass the return bends 18 on the opposite ends of the tie 10 while, at the same time, terminating short of the stop or so-called spreaders 20 formed by the free ends of the wire at the extremities of the two-wire twisted cable section 22 that occupies the medial portion of the upper strand 24. The lower single-wire strand 26 parallels the upper strand in spaced relation therebeneath and supports the tie in the base of the tie slots.

The upper and lower strands including the two-wire cable .section of the former cooperate with the inner and outer returnbends 18B and 18A interconnecting same to define an elongate endless loop 32. A single length of wire is used to form this loop, the total elngth of which is somewhere between three and four times the length ofthe finished tie.

Prior to forming the loop, however, it is advisable to bend the stops or spreaders 20 and the upwardly opening U-shaped saddles 34 in the opposite extremities of the wire as these features are useful for gripping the ends while the two-wire cable is twisted. Once the ends have been shaped as above-noted, a little less than onethird of the wire as thus foreshortened is bent over at each end to produce return bends 18 having a radius slightly in excess of that of the tie rod to be used therewith. The return bends 18 are not equidistant from the spreaders 20, but rather, are preferably spaced therefrom slightly different distances so that the tie rod opening 36A in one end is somewhat smaller than the companion opening 368 in the other end. More specifically, the horizontal distance measured from the outermost point on the spreader 20A where it contacts the interior surface of the outside form panel I 12A and the outermost point on the inside of the smaller tie rod opening 36A should be substantially equal to the thickness of the form panel plus the diameter of the tie rod. When this condition exists, the weight of the outside tie rod 14A is sufficient to pivot the tie into the essentially horizontal position shown in FIG. 2 using spreader 20A as a fulcrum. Prior to insertion of the tie rod 14A, the tie will slope down onto the right within the confines of the tie slot 16A so as to enlarge tie slot 36A sufficiently to easily receive the tie rod.

With the tie in the horizontal position shown, on the other hand, tie rod 148 would be most difficult to insert through tie rod opening 368 if the latter were the same size as opening 36A. For this reason, tie rod opening 368 is the same height as opening 36A but is somewhat elongated to easily pass rod 148. This enlargement is, of course, brought about by spacing spreader 208 a greater distance from the inside of inside return bend 183 than the distance represented by the outside diameter of tie rod 148 and the thickness of form panel 128.

The two-wire cable section 22 separating the spreaders 20 and saddles 34 in the upper strand 24 is formed by gripping thesections beyond the return bends at longitudinally spaced points so as to hold them in side-by-side relation while they are grasped at a point midway therebetween and twisted. In the particular form shown, the wires have been held at the points where the spreaders 20 begin while being twisted. In a tie of the length shown, four complete twists on each side of the center can be made. Also, note that the center section 42 can unwind to relieve any residual torsional stresses resulting from formation of the cable and end up in any angular position relative to the stops and plane of the loop without adverse effect thereon.

The upwardly opening U-shaped saddles 34 are formed on the inside of the spreaders 20 and are spaced from the adjacent interior form panel surface so as to hold the rebar 38 in the precise position known to produce maximum reinforcing action. This position is customarily the one prescribed in the building codes. The width of the saddles is selected to loosely accept the rebar and its depth'is such that the rods are securely restrained against movement toward or away from the form wall. Even though the rebar rods are bent and do not seat securely in each saddle, the tie-spacing is such that it will seat in enough of them to maintain a proper relation to the form panel while being encased in concrete. Holding the rebar in proper position 'can usually be accomplished by tieing it to the endmost ties, ordinarily some twenty feet apart.

Once the inside form panel 128 is moved in against spreader 20B, the other rebar rod (not shown) is laid in its saddle and the inside tie rod passed through its open ing 368, the forms are doubled up" ready to pour. The spreaders 20, of course, hold the form panels apart while the concrete is poured therebetween. The hydrostatic forces exerted by the wet concrete quickly push the inside form panel outwardly until it pushes tie rod 143 up snug against the return bend. This will result in the inside rebar rod (not shown) being spaced inwardly of inside form panel 12B a fraction of an inch more than the other rod 38A, however, the difference is so slight as to be inconsequential. Obviously, one could, if

necessary, reform spreader loop 208 so as to bring the adjacent saddle 3613 up closer to the form panel thus adjusting for this slight discrepancy but to do so is unnecessarily complicated when no tangible advantage would result from so doing.

Finally, since the differences in opposite ends of the tie are not readily recognizable by eye, it is a good idea to provide at least one end with some identifying indicia 48 such as painting it a characteristic color. An alternative to paint might be some sort of a nick or other imperfection (not shown).

What is claimed is:

l. The twisted wire concrete form tie which comprises: a single length of wire bent to define a closed loop having a single-wire lower strand interconnected at opposite extremities to a double-wire upper strand by open return bends, the double-wire upper strand being spaced from said single wire strand and being twisted from its midpoint outwardly in both direction to define a cable section terminating short of the free ends, and both remaining portions between the cable section and the free ends being bent to define upstanding stops spaced inwardly of the adjacent return bend and upwardly opening U-shaped saddles adjacent said stops on the inside thereof adapted to receive and retain a reinforcing rod laid therein.

2. The twisted wire concrete form tie as set forth in claim 1 in which: the upstanding stops comprise open loops defined by curling the free ends up, over and back down onto the cable section.

3. The twisted wire concrete form tie as set forth in claim 1 in which: the upper and lower strands lie in spaced substantially parallel relation to one another.

4. The twisted wire concrete form tie as set forth in claim 1 in which: the stops are located different distances from their respective return bends.

5. The twisted wire concrete form tie as set forth in claim 4 in which: indicia is provided on one end of the tie to distinguish the ends having different stop spacings.

6. The twisted wire concrete form tie as set forth in claim 4 in which: the horizontal distance separating the outermost point on the inside of the return bend and the outermost point on the adjacent stop on one end of the tie with the latter level is substantially equal to the sum of the thickness of the form panel and outside diameter of the reinforcing bar to be placed therebetween; and, in which the corresponding distance on the opposite end of the tie is greater.

Claims (6)

1. The twisted wire concrete form tie which comprises: a single length of wire bent to define a closed loop having a single-wire lower strand interconnected at opposite extremities to a doublewire upper strand by open return bends, the double-wire upper strand being spaced from said single wire strand and being twisted from its midpoint outwardly in both direction to define a cable section terminating short of the free ends, and both remaining portions between the cable section and the free ends being bent to define upstanding stops spaced inwardly of the adjacent return bend and upwardly opening U-shaped saDdles adjacent said stops on the inside thereof adapted to receive and retain a reinforcing rod laid therein.

2. The twisted wire concrete form tie as set forth in claim 1 in which: the upstanding stops comprise open loops defined by curling the free ends up, over and back down onto the cable section.

3. The twisted wire concrete form tie as set forth in claim 1 in which: the upper and lower strands lie in spaced substantially parallel relation to one another.

4. The twisted wire concrete form tie as set forth in claim 1 in which: the stops are located different distances from their respective return bends.

5. The twisted wire concrete form tie as set forth in claim 4 in which: indicia is provided on one end of the tie to distinguish the ends having different stop spacings.

6. The twisted wire concrete form tie as set forth in claim 4 in which: the horizontal distance separating the outermost point on the inside of the return bend and the outermost point on the adjacent stop on one end of the tie with the latter level is substantially equal to the sum of the thickness of the form panel and outside diameter of the reinforcing bar to be placed therebetween; and, in which the corresponding distance on the opposite end of the tie is greater.

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