US 3069743 A
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Description (OCR text may contain errors)
Dec. 25, 1962 w. J. LUYBEN CONCRETE FORM TIE Filed July 1, 1960 INVENTOR. WILLIAM J. LUYBEN United States Patent tifice 3,069,743 Patented Dec. 25, 1962 3,069,743 CONCRETE FORM TIE William J. Luyben, 14005 NE. Marine Drive, Portland, Greg. Filed July 1, 1960, Ser. No. 40,383 2 Claims. (Cl. 25-131) This invention relates to improvements in ties used for maintaining the proper spacing of panels in concrete forms for walls and the like.
Such ties usually have opposite ends projecting through holes in the form panels and extending between pairs of closely spaced walers which are arranged to prevent spreading of the panels under the pressure of the concrete when the latter is poured into the wall space between the panels. The ends of the ties are equipped to receive special wedges engaging the outer surfaces of the walers or other stiffening members employed. The ties are also usually equipped with spacing elements to hold the form panels apart before the concrete is poured and it is common practice further to provide the ties with reduced neck portions whereby the ends of the ties may be broken off beneath the surface of the concrete after the concrete has hardened.
The provision of these various desirable features has made the presently available form ties a relatively expensive item in connection with the construction of concrete walls. The broken ends constitute a waste and the wedges themselves are such an item of expense that small contractors not regularly engaged in wall construction often rent them to save the purchase price.
The general object of the present invention is, therefore, to provide form ties and wedges of the type described which can be manufactured and sold at lower cost than conventional ties and wedges.
Other objects are to provide an improved form tie which incurs less Waste for the contractor, to provide a form tie which eliminates the necessity for purchasing or renting wedges, and, specifically, to provide a form tie in which the broken ends themselves are utilized as wedges.
The present tie is so designed that each end which is broken off when the forms are stripped provides a wedge for use with a new set of form ties on a later job. Thus, after the first job, the contractor is automatically supplied with wedges from portions of the tie which had previously been considered as waste. This advantageous result is accomplished by tapering the end portions of the tie to wedge shape, the small end of the wedge forming the break point where the end is broken off when the forms are stripped. This eliminates the purchase or rental of wedges and reduces the total expense of the ties in a continuing operation.
The foregoing and other objects and advantages will become aparent and the invention will be better understood with reference to the following description of the preferred embodiment illustrated on the acocmpanying drawing. Various changes may be made, however, in the details of construction and all such modifications within the scope of the appended claims are included in the invention.
In the drawing:
FIGURE 1 is a vertical cross sectional view, showing the present tie in a concrete form after the wall has been poured;
FIGURE 2 is a sectional view on a horizontal plane, showing the form in the process of erection preparatory to receiving the concrete; and
FIGURE 3 is a perspective view of the present tie, showing how a broken end is used as a wedge.
Referring first to FIGURE 3, the present tie comprises a flat metal bar having a center spreader portion 11 extending between a pair of outwardly facing shoulders 12. The configuration of this center portion is not important except that it preferably includes some retention means to lock it in the concrete, such as openings 13.
Each shoulder 12 constitutes one side of a notch 14 which reduces the cross section of the bar to provide a weakened break point 15 at the point of greatest depth of the notch which is at shoulder 12. The other side of the notch is formed by a tapered edge 16 which extends for a considerable distance outwardly from shoulder 12 at a suitable wedging angle relative to the straight back edge 17. The wedge surface preferably ends at a point 18 some distance from the end 19 to leave an end portion 20 of uniform width which, for convenience of manufacture, is the same width as center portion 11. End portion 24} is equipped with a rectangular hole 21 having a length slightly less than the width of end portion 20 to receive the wedge 25. Wedge 25, it will be observed, is the end of another tie which has been broken off at the point 15.
Referring now to FIGURE 2, the numeral 30 designates a pair of upright form panels between which concrete is to be poured to form a wall. These panels are stiffened and prevented from spreading apart by pairs of horizontal walers 31. Round holes 32 are bored in the panels 30 between the walers 31 to receive the tie 10. Shoulders 12 engage the inside surfaces of the panels to hold them apart a distance slightly less than the intended thickness of the wall. The ends of the tie project from between the walers 31 with the inside edges of holes 21 spaced slightly beyond the outside surface of the walers.
Wedges 25 inserted in the holes 21 prevent the spreading of the form panels when the concrete is poured, as shown in FIGURE 1, the distance between the inside edges of holes 21 determining the thickness of the wall. The pressure of the concrete against panels 30 forces walers 31 back against the wedges, spreading the panels 30 apart to a spacing slightly greater than the distance between shoulders 12. This locates the break points 15 beneath the surface of the concrete so that no part of the metal tie projects from the finished wall after the ends have been broken off.
In stripping the form, wedges 25 are first removed and then the ends of the ties may be broken off through the holes 32 by bending them back and forth horizontally in the space between the walers 31. The ties are preferably hardened, at least in the regions of the notches, to facilitate such breaking. When the ends of all the ties have thus been broken off, they offer no obstruction to the stripping of the forms. As many of the broken ends of the ties may be saved as may be necessary for future work. The present wedges also have the further advantage that they cannot rotate 0n the tie rods and become accidentally disengaged therefrom before the rods are tensioned by the pouring of the concrete, as frequently happens with certain conventional wedging arrangements.
In the illustrated embodiment, the panels 30 are plywood panels and the walers 31 are 2" x 4 lumber. The distance between abutment shoulder 12 and the inside end of hole 21 is sufficiently greater than the combined thickness of panel 30 and width of waler 31 to locate break point 15 under the surface of the concrete as above mentioned when green lumber is used for the walers. If the walers shrink from drying before the concrete is poured, the break points will be submerged to a slightly greater depth in the concrete and the wall will be slightly thicker whereby no objectionable dimensional variation occurs. It will be apparent that the present ties, in appropriate dimensions, may also be used in forms with vertical studs instead of horizontal walers and in forms without either studs or walers. The present ties are not limited to wood form construction, however.
While the shape of the tie bar is susceptible to certain variations, the particular configuration of the preferred embodiment permits it to be stamped economically from fiat strap or band stock. The present configuration also permits bars of different lengths for different wall thicknesses to be stamped from the same dies. This is accomplished by stamping each end in a separate operation. In this way, the length of the center portion 11 does not affect the stamping operation. This method entails no extra work because the stamping die may be made to form the ends of two different bars simultaneously. Thus, two stamping Operations form two ties as would be the case if each tie were completely formed in a single stamping operation.
A desirable dimensional relationship to be observed is that the length of hole 21 should be equal to the width of the wedge at approximately its mid-point between its small end 15 and its large end 19 so that its back edge 17 will have a substantial bearing length on opposite sides of the tie bar in FIGURE 1.
Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is:
1. A tie for concrete forms and the like comprising a flat strip of metal of straight edged rectangular crosssection having rectangular wedge engaging apertures adjacent each end; form engaging shoulders formed within the cross-section of the body of the strip, each shoulder facing outwardly toward its own adjacent end of the strip, the bottoms of said shoulders being joined to the full cross-section of the strip by outwardly directed bevels, the slope of said bevels being at a suitable wedging angle relative to a straight back edge, the width of the crosssection of said strip at said shoulders being less than the length of said wedge engaging apertures and said strip being frangible at said shoulders.
2. A tie for concrete forms and the like comprising a fiat strip of metal of substantially rectangular crosssection having wedge engaging apertures adjacent each end; form engaging shoulders formed substantially within the cross-section of the body of the strip, each shoulder facing outwardly toward its own adjacent end of the strip, the bottoms of said shoulders being joined to the full cross-section of the strip by outwardly directed bevels, the slope of said bevels being at a suitable wedging angle relative to the opposite edges, the width of the cross-section of said strip at said shoulders being less than the length of said wedge engaging apertures and said strip being frangible at said shoulders.
References Cited in the file of this patent UNITED STATES PATENTS 845,635 Ham Feb. 26, 1907 1,708,634 Rees Apr. 9, 1929 1,978,963 Schwaab Oct. 30, 1934 2,245,559 Kinninger June 17, 1941 2,501,412 Schaefer Mar. 21, 1950 2,618,039 Hyre Nov. 18, 1952 2,709,292 Otti May 31, 1955 2,773,294 Pilling Dec. 11, 1956 2,775,018 McLaughlin Dec. 25, 1956 FOREIGN PATENTS 105,374 Germany Sept. 29, 1899 255,509 Great Britain July 21, 1926