US3338018A - Rebar chair with plural feet - Google Patents

Description

,1967 Q A. G. MESS, JR 3,338,018

REBAR CHAIR WITH PLURAL FEET Filed Feb. 25, 1966 INVENTOR. ARTHUR G. MESS,JR.

ATTORNEY United States Patent 3,338,018 REBAR CHAIR WITH PLURAL FEET Arthur G. Mess, Jr., Ceuterville, Ohio, assignor to The Dayton Sure-Grip and Shore Company, Miamisburg, Ohio, a corporation of Ohio Filed Feb. 25, 1966, Ser. No. 530,149 9 Claims. (Cl. 52-687) This application is a continuation-in-part of copending application Ser. No. 430,410, filed Feb. 4, 1965, and now abandoned and assigned to the same assignee.

This invention relates to improvements in supports for concrete reinforcing steel, and more particularly, to a reinforcing bar support having corrosion resistant foot members on the ends thereof.

In view of the fact that the supports for concrete reinforcing steel remain in the concrete, it is desirable that the cost of these supports be held at a minimum. For this reason the supports are usually formed from bright basic steel wire which is a low cost steel but will rust when subjected to the atmosphere for an extended period of time. Thus there is a significant problem with the ends of the support legs which rest against the forms and are not sealed from the air by concrete. This problem is especially serious in seacoast areas where salt water causes extensive rusting.

This corrosion is particularly noticeable with the reinforcing steel supports commonly used for a poured concrete floor. Here, the ends of the legs of each support are in pressure contact with the form as a result of the weight of the reinforcing steel carried by the supports. Thus when the forms are removed, the ends of the legs are exposed, and unless they are protected in some manner, rust spots will in time form on the underneath side of the floor. These rust spots are particularly undesirable in a building where the underneath surface of the floor serves as the ceiling of the room below.

Furthermore, it is frequently necessary to grind the underneath surface of a floor or outside surface of a wall to remove irregularities in the surface of the concrete due to corresponding irregularities in the forms. When this grinding operation is performed, it results in removing a portion of the bottom ends of the support legs. Thus even when a coated support is used, as for example, a galvanized or plastic coating, the coating may be removed from the bottom end of the leg by the grinding operation, which in turn exposes the non-corrosion resistant basic steel wire directly to the atmosphere.

Several methods have been tried for protecting the bottom ends of the supports, including the dipping of the bottom end portions of the legs into a plastisol material or covering the ends with a plastic cap. It has been found, however, that when the thickness of the plastic material is relatively thin, the plastic is subject to cold flowing due to the weight of the reinforcing steel, so that the plastic coverage on the bottom tip of the leg becomes thin, and sometimes the bottom end of the leg breaks through the thin plastic coating so that it is exposed to the atmosphere.

On the other hand, when the plastic coating or plastic cap is provided with sufiicient wall thickness to prevent the possible exposure of the support leg due to the supported weight, the coefiicient of expansion of the plastic material becomes a significant factor. For example, it has been found that with a relatively thick-walled plastic cap on the bottom ends of the support legs, an increase in temperature of the concrete has caused the plastic to expand considerably more than the surrounding concrete and resulted in cracking and chipping the concrete in the area surrounding the plastic cap. Thus it is preferred that the reinforcing support be constructed entirely from steel,

since the coefficient of expansion for steel is substantially the same as concrete.

Accordingly, it is a primary object of the invention to provide an improved support for concrete reinforcing steel, which is inexpensive to construct and provides a corrosion resistant surface in contact with the form in addition to having an overall coefiicient of expansion compatible with the concrete.

As another object the invention provides a concrete reinforcing bar support which is constructed primarily from low cost bright basic steel wire with extending legs having ends which are spaced from the form by a stainless steel foot member secured to the end of each leg.

Still another object of the invention is to provide an improved support for reinforcing steel, as outlined above,

wherein a commercially available and low cost stainless steel spherical foot member is welded to the end of each support leg to prevent the ends of the legs from being exposed to the atmosphere and thereby being subjected to corrosion.

A further object of the invention is to provide an improved support for reinforcing steel, as outlined above, wherein a commercially available and low cost stainless steel rivet is welded to the end of each support leg to provide a foot member which protects the ends of each leg from being subjected to corrosion.

A further object of the invention is to provide a low cost support for concrete reinforcing steel including legs with corrosion resistant stainless steel foot members spaced adjacent the forms so that the surface of the concrete can be ground without the danger of exposing to the atmosphere the non-corrosion resistant portion of the support.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawing and the appended claims.

In the drawing- FIG. 1 is a perspective view of a typical concrete reinforcing steel support commonly referred to as a slab bolster and including the improvement according to the present invention;

FIG. 2 is an enlarged detailed view of the lower end portion of a support leg provided with a stainless steel foot member in accordance with the present invention;

FIG. 3 is a perspective view of another typical reinforcing bar support, commonly referred to as a high chair, and also provided with a stainless steel spherical foot member on the downwardly depending legs;

FIG. 4 is a fragmentary view of a typical application for the support shown in FIG. 3;

FIG; 5 is an enlarged fragmentary sectional view showing the spaced relationship of the lower portion of a support leg and foot member with the lower surface of a concrete floor;

FIG. 6 is an enlarged fragmentary View of a reinforcing steel support having legs provided with stainless steel foot members in accordance with another embodiment of the present invention; and

FIG. 7 is a fragmentary view similar to FIG. 2 and showing still another foot construction in accordance with the invention.

Referring to the drawing, which illustrate preferred embodiments of the present invention, the slab bolster or support 10 shown in FIG. 1 includes a generally horizontally extending wire 12 welded to and supported by the wire legs 15 which serve to space the wire 12 substantially above the top surface 16 of the form. As illustrated, the end of the wire 12 serves to support the con crete reinforcing bars 18 which are usually formed from low cost hot rolled bars. Preferably, the support 10 is formed from a bright basic steel wire and is formed by resistance welding the legs 15 to the wire 12 while the legs remain straight, that is, before they are formed into the inverted U-shape'd configuration shown in FIG. 1.

While the support is a flat form, and the legs 15 extend straight and parallel, a stainless steel spherical foot member is welded on the ends 22 of each leg 15 so that after the legs 15 are formed downwardly, the feet 20 are adapted to rest against the top surface 16 of the form and serve as a spacer for the ends 22 of the legs 15. As shown in FIG. 2, the spherical foot member 20 is fastened to the end of the leg 15 by a resistance or autogenous welding operation well known in the art.

It has been found that due to the high volume of stainless spheres used in the ball bearing industry, the stainless steel spherical foot members 20 are commercially available at relatively low cost in a semi-finished condition after'an initial automatic grinding operation. In addition, the spherical shape is desirable in that it requires less volume of stainless steel material to provide a high strength spacer for the ends 22 of the legs when compared to a cylindrical shape of the same diameter. The spherical foot member 20 is also desirable from a handling standpoint when the foot member is welded to the end 22 of the leg 15, for the reason that it is not necessary to orientate the foot member prior to its being welded to the leg. Furthermore, from a resistance welding standpoint, the spherical foot member 20 provides a point contact with the bottom end 22 of the leg 15, and thus provides for a maximum concentration of heat at the point of weld, which results in a rigid and fast weld ideal for high production of the supports.

It is preferred that the spherical foot member 20 have a diameter slightly greater than the diameter of the Wire leg 15 so that the foot member can be more conveniently supported and retained during the welding operation without interfering with the leg 15. For example, with a No.

7 gauge (.177") wire leg, a 7 diameterspherical foot' member has been found desirable, and the use of a 5 diameter foot member with a No. 2 gauge (.263) wire leg.

Another typical support 25 is shown in FIGS. 3 and 4 and includes downwardly extending legs 27 on the ends of which have been welded spherical foot members 20. The upper portion of the support 25 is provided with a nest 30 which is adapted to support the cross wires 32 forming the reinforcing mat 35 (FIG. 4). It is to be understood, however, that while a support formed in accordance with the invention is primarily suited for supporting reinforcing steel for a concrete floor, the improved foot member could also be employed in supports for positioning and retaining reinforcing steel'in a vertical concrete wall where the problem exists of undesirable rust spots forming on the surface of the wall at the point of contact between the support and the form.

The lower end portion of a leg 15 and adjoined spherical foot member 20 are shown in FIG. 5 in relation to the surrounding concrete 38 having a bottom surface 40; As can be seen, the bottom end 22 of the leg 15 is spaced above the surface 40 by the diameter of the spherical foot member 20. Thus when it is necessary to finish the surface 40 by grinding it down to the level represented by the dotted line 42, the end 22 of the wire leg 15 is still spaced by an appreciable distance from the surface 40. As a result, the removal of the bottom portion of the stainless steel spherical foot member 20 does not increase the danger of rust spots forming on the surface 40 due to the inherent corrosion resistance throughout the stainless steel.

FIG. 6 shows another embodiment of the invention comprising a portion of reinforcing steel support 50 having a pair of legs 52 formed by bending a bright basic steel wire into an inverted U-shaped configuration. The legs 52 have slightly hooked lower end portions 53 and serve to space a cross support wire 55 above the top surface 16 of the form. A stainless steel foot member 60 is provided on each leg 52 by welding a flat head stainless steel rivet to the lowermost surface on each leg end portion 53.

The rivet-type foot member 60 includes a cylindrical connecting portion 61 and a head portion 62 having a flat end surface 65 which preferably lies in a common plane with corresponding such surfaces of other foot members so that all of the foot members rest flatly against the form surface 16. It has been found that the flat end surface 65 of each foot member 60 provides a substantial load bearing surface which prevents the weight of reinforcing steel resting on the wire 55 for a concrete floor from causing the foot member to penetrate or deform the form surface 16 and thereby cause the foot member to project from the underneath surface of the concrete floor after the forms are removed.

As mentioned above for the stainless steel spherical foot members 20 which are formed from balls commonly used in the ball bearing industry, the foot members 60 are formed from rivets which are commonly used in the fabrication of corrosion resistant articles and thus are also commercially available at a relatively low cost and sometimes at a cost lower than that of the balls. Also, for conveniently handling the foot member 60 during the welding operation and for providing a substantial load bearing end surface 65, preferably the head portion 62 of each foot member is slightly greater in diameter than the diameter of the wire forming the corresponding leg 52. For example, with a No. 7 gauge (.177") wire leg, a stainless steel rivet having a head diameter of approximately .300 inch has been found desirable.

As also mentioned above for the spherical foot member 20, the grinding of the head portion 62 of each foot member 60 during the subsequent grinding of the concrete surface does not increase the danger of exposing the lowermost surface of the corresponding leg portion 53 and thus does not increase the danger of rust spots forming on the surface of the concrete. Furthermore, since concrete completely surrounds the connecting portion 61 of each foot member 60, the head portion 62 serves as a baflie or barrier for preventing moisture from reaching the non-corrosion resistant leg portion 53 along the outer surface of the foot member 60 after an extended period of time.

FIG. 7 shows another embodiment of the invention wherein another form of rivet type foot member is welded to the end 22 of each leg 15 in place of welding a spherical foot member as shown in FIG. 2. The foot member 70 is formed from a stainless steel truss head or wagon box rivet which is also commercially available at relatively low cost and includes a shank portion 72 and an integral circular head portion 73 with a curved end surface 75 having a relatively large constant radius.

As mentioned above for the foot member 60, preferably the diameter of the head portion 73 is somewhat larger than the diameter of the wire leg 15. For example, with a wire leg having a diameter of .225 inch, a stainless steel truss head rivet having a head diameter of .287 inch performs satisfactorily. This slightly larger head enables the rivet to be more conveniently handled during the automatic welding operation and also providing a bafiie effect for preventing moisture from reaching the end portion of the leg 15 in the same manner as explained above for the foot member 60.

From the drawing and the above description, it can be seen that a support according to the present invention provides several desirable advantages and features. Basically, due to the commercial availability of stainless steel spheres and rivets at relatively low cost, a support formed with a stainless steel foot member of either type on each leg provides not only resistance to corrosion of the surface in contact with the form but also an overall low cost. The low cost is in part due to the adaptability of the foot member to be easily handled without requiring complex fixturing prior to the welding on the bottom end portion of the support leg. Thus the fast welding of a foot member with concentrated heat on each leg is ideally suited for automatic operation which provides for an overall low cost.

Furthermore, it is a primary advantage of a support formed in accordance with the invention that the entire support including each foot member is formed of steel and thus has a uniform coefiicient of expansion which is substantially the same as the concrete. This eliminates differential expansion if the temperature of the concrete is subjected to increases during the summer and decreases during the winter. As a result, it has been found that a support formed in accordance with the invention prevents the fracturing of the portion of the concrete surrounding the lower end of the leg. Other features are provided by the embodiment shown in FIG. 6 wherein the flat contacting head surface 65 of each foot member 60 prevents deforming of the form surface 16 and the head portion 62 prevents moisture from reaching the end portion 53 of the corresponding leg 52.

Other important features are provided by the foot member 70 shown in FIG. 7. That is, the truss head rivet provides a curved surface 75 having a relatively large radius which is desirable to provide more of an area contact with the form surface 16 and thereby prevent sinking of the foot member 70 into the form surface due to the weight of the reinforcing steel. In addition, the truss head rivet provides a foot member having a curved surface of large radius with a minimum amount of stainless steel material. Furthermore, by welding the foot member 70 on the end 22 of each leg 15, the length of wire material required for constructing the legs is minimized, and it is unnecessary to position a leg precisely since the curved surface 75 will accommodate a leg extending downwardly at practically any angle which provides high support strength without collapsing.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. An improved support for positioning concrete reinforcing steel according to a predetermined spaced relationship with a form and to prevent rust spots from forming on the surface of the concrete where the support is exposed as a result of contact with the form, comprising a support portion including a plurality of extending legs, said support portion and legs being formed from low cost basic steel material which is non-resistant to corrosion, a stainless steel foot member fastened rigidly to the end of each said leg and adapted to rest against the form and to space the end portion of said leg from the form, said foot member having a coeflicient of expansion substantially the same as said support portion to provide for uniform and compatible expansion between the entire support and the surrounding concrete with increases in temperature, and said foot member being adapted to provide a corrosion resistant portion in contact with the form so that the subsequent grinding of the member with the grinding of the concrete surface does not effect the corrosion resistance of said foot member.

2. A support as defined in claim 1 wherein each said stainless steel foot member has a convexly curved end surface for minimizing the area of engagement between said surface and the form.

3. A support as defined in claim 1 wherein each said foot member is autogenously welded to the end portion of the corresponding said leg.

4. A support as defined in claim 1 wherein each said foot member is spherical in configuration and is Welded to the end portion of the corresponding said leg.

5. A support as defined in inforcing steel in a poured concrete floor and for preventing rust spots from forming on the underneath surface of the floor, wherein each said leg extends downwardly from said support portion, and said foot member is Welded to the lower end portion of each said leg.

6. A support as defined in claim 1 wherein each said foot member is formed from a stainless steel rivet.

7. A support as defined in claim 6 wherein each said foot member is formed from a truss head rivet including a shank portion and a head portion having a curved end surface of substantial radius, and weld means joining said shank portion to said end portion of said leg so that said end surface rests against said form.

8. A support as defined in claim 6 wherein each said foot member includes a head portion extending from a connecting portion, and said connecting portion is welded to the end portion of said leg so that the head portion is spaced from said end portion of said leg for resting against the form to reduce the chances of moisture seeping around the outer surface of the foot member and reaching the end portion of said leg.

9. A support as defined in claim 8 for positioning reinforcing steel in a poured concrete floor and for preventing rust spots from forming on the underneath surface of the floor, wherein the head portion of each said foot member includes a flat end surface, and said foot member is welded to the end portion of the corresponding leg so that said end surface rests substantially flat against the form for the floor to provide a substantial load bearing surface and thereby to prevent the foot member from penetrating the form.

References Cited UNITED STATES PATENTS 1,457,610 6/1923 White 52688 2,471,937 5/1949 COlwell 29486 2,823,539 2/1958 Kersh et a1. 52678 FOREIGN PATENTS 649,193 9/1964 Canada. 487,491 6/ 1938 Great Britain. 898,810 6/ 1962 Great Britain.

OTHER REFERENCES Designing Parts for Cold and Hot Heading, Industrial Fasteners Institute, 1517 Terminal Tower, Cleveland, Ohio, First Edition, 1958, pages 32, 47, 53-58.

FRANK L. ABBOTT, Primary Examiner. J. L. RIDGILL. Assistant Examiner.

claim 1 for positioning re- 1

Claims (1)

1. AN IMPROVED SUPPORT FOR POSITIONING CONCRETE REINFORCING STEEL ACCORDING TO A PREDETERMINED SPACED RELATIONSHIP WITH A FORM AND TO PREVENT RUST SPOTS FROM FORMING ON THE SURFACE OF THE CONCRETE WHERE THE SUPPORT IS EXPOSED AS A RESULT OF CONTACT WITH THE FORM, COMPRISING A SUPPORT PORTION INCLUDING A PLURALITY OF EXTENDING LEGS, SAID SUPPORT PORTION AND LEGS BEING FORMED FROM LOW COST BASIC STEEL MATERIAL WHICH IS NON-RESISTANT TO CORROSION, A STAINLESS STEEL FOOT MEMBER FASTENED RIGIDLY TO THE END OF EACH SAID LEG AND ADAPTED TO REST AGAINST THE FORM AND TO SPACE THE END PORTION OF SAID LEG FROM THE FORM, SAID FOOT MEMBER HAVING A COEFFICIENT OF EXPANSION SUBSTANTIALLY THE SAME AS SAID SUPPORT PORTION TO PROVIDE FOR UNIFORM AND COMPATIBLE EXPANSION BETWEEN THE ENTIRE SUPPORT AND THE SURROUNDING CONCRETE WITH INCREASES IN TEMPERATURE, AND SAID FOOT MEMBER BEING ADAPTED TO PROVIDE A CORROSION RESISTANT PORTION IN CONTACT WITH THE FORM SO THAT THE SUBSEQUENT GRINDING OF THE MEMBER WITH THE GRINDING OF THE CONCRETE SURFACE DOES NOT EFFECT THE CORROSION RESISTANCE OF SAID FOOT MEMBER.

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