Coupling between slab bolster elements

Two slab bolster elements having rails supported on legs for carrying rebar during casting are connected end to end by a blade for sliding longitudinally of the rail into a female receptacle and a releasable locking mechanism which acts to lock the blade in the female receptacle. The locking mechanism comprises a notch on one side surface of the blade and a projecting portion of the female receptacle engaged into the notch. The projecting portion is carried on the female receptacle by a portion which can flex to cause the projecting portion to move away from the side surface of the blade. The female receptacle includes a manually depressible member on a side of the female receptacle opposite the projecting portion which when depressed provides motion toward the female receptacle which causes the projecting portion to move out of the notch.

This invention relates to a slab bolster elements of the type having an injection molded frame defining a rail for supporting reinforcing bars laid across the rail and a plurality of legs for supporting the rail at a position spaced from a support surface so that a filler material laid on the support surface covers the reinforcing bars and the rails, and particularly to a coupling having a male coupling at one end of one element for connection to a female coupling at an end of the frame of a second bolster element.

Typically in such arrangements, the male coupling has a blade projecting longitudinally of the rail for sliding into a female receptacle of the female coupling and there is provided a locking mechanism which acts to lock the blade in the female receptacle to hold the first and second elements together in a connected position.

Slab bolsters are relatively lightweight frame members that are positioned at spaced intervals on a deck or grade within a slab form to support concrete reinforcing bar prior to the pouring of wet concrete. After placing the slab bolsters in position within the slab form, rebar may be positioned so as to extend between and across the support surfaces of parallel slab bolsters. Such slab bolsters are frequently attached to other similar bolsters in a linear relationship to form a continuous bolster extending across the width of the slab form.

SUMMARY OF THE INVENTION

It is one object of the present invention to provide a locking mechanism which is readily releasable to allow the elements to move apart.

According to the invention there is provided slab bolster elements having a coupling for connection of two of the slab bolster elements end to end comprising:

first and second slab bolster elements each having an injection molded frame defining a rail for supporting reinforcing bars laid across the rail and a plurality of legs for supporting the rail at a position spaced from a support surface so that a filler material laid on the support surface covers the reinforcing bars and the rails;

the rail having a top surface onto which the bars are laid and two side surfaces;

the frame of the first bolster element having a male coupling at one end for connection to a female coupling at an end of the frame of the second bolster element;

the male coupling comprising a blade projecting longitudinally of the rail for sliding into a female receptacle of the female coupling;

the first and second slab bolster elements having a locking mechanism which acts to lock the blade in the female receptacle to hold the first and second elements together in a connected position which is releasable to allow the elements to move apart;

the locking mechanism comprising a notch on one side surface of the blade of the first element and a projecting portion of the female coupling of the second element which is, in the connected position, engaged into the notch to hold the blade against movement away from the second element;

the projecting portion being carried by a flexible mounting on female coupling of the second element which can flex to cause the projecting portion to move in a direction away from the side surface of the blade out of the notch to allow the blade to move out of the female receptacle;

the female coupling of the second portion including a manually depressible member on a side of the female receptacle opposite the projecting portion which when depressed provides motion toward the female receptacle;

and the female coupling of the second portion including a connecting portion connecting the manually depressible member to the projecting portion so that the motion of the manually depressible member causes the projecting portion to move out of the notch.

Preferably the connecting portion extends underneath the blade. However it can also be located across the top of the blade.

Preferably the connecting portion is connected to the female receptacle on each side of the blade by a respective one of a pair of flexible arm portions. However the connection to the female receptacle may be on only one side.

Where it is connected on both sides, preferable the connecting portion is connected to the female receptacle on each side of the blade by a respective one of a pair of flexible arm portions.

Typically the female receptacle includes a top wall, a bottom wall and two side walls defining an open mouth into which the blade is inserted and each of the flexible arm portions extends alongside a respective one of the side walls of the female receptacle. In this arrangement preferably each of the flexible arm portions is connected to the respective side wall of the female receptacle and is inclined outwardly therefrom to the respective side.

Preferably the top wall of the female receptacle is coplanar with the top surface of the rail and in this case the connecting portion preferably forms a bar extending underneath the blade so as not to interfere with the top of the receptacle. In this case preferably the bar has an upper surface in sliding contact with the blade.

In order to ensure proper support of the rails at the connection, preferably the frame of the first bolster element includes a first cross member across the rail at the male coupling with a leg at each end of the first cross member and the frame of the second bolster element includes a second cross member across the rail with a leg at each end of the second cross member.

DETAILED DESCRIPTION

Slab bolster elements10and11are provided with a coupling12for connection of two of the slab bolster elements end to end so that an end13of one is connected to the end14of the other.

The first and second slab bolster elements10,11each have an injection molded frame15defining a rail16for supporting reinforcing bars17(FIG. 4) laid across the rail. The rails are supported on a plurality of legs18for supporting the rail16at a position spaced from a support surface so that a filler material (typically concrete) laid on the support surface covers the reinforcing bars and the rails.

The rail has a top surface161onto which the bars17are laid and two side surfaces162,163. The legs are connected to the underside and extend downwardly to the support surface (not shown).

The frame15of the first bolster element10includes a first cross member19at right angles across the rail16of the first element on one side of the coupling12with a leg181and182at each end of the first cross member and the frame of the second bolster element11includes a second cross member191at right angles across the rail16on the other side of the coupling12with a leg183,184at each end of the second cross member. These cross members and their supporting legs provide stability to the rails. Further such cross members can be provided at spaced positions along the rails which may be many feet in length.

The frames are formed typically by injection molding to form the rails, legs and coupling in a single molding step as an integral element.

The coupling12as best shown inFIG. 2, has a male coupling20at one end of the element10for connection to a female coupling21at an end of the frame of the second bolster element11.

The male coupling20comprising a blade201projecting longitudinally of the rail for sliding into a female receptacle211of the female coupling21.

The blade201is generally flat with a top surface202, a bottom surface203two side surfaces205and a front end204. The blade tapers slightly toward the front end so that it can more easily be inserted into a mouth of the female receptacle. The surfaces of the blade may be flat or may be recessed as shown to reduce material content in the molded structure.

The female receptacle211includes a top wall212, a bottom wall213and two side walls214defining an open mouth215into which the blade is inserted and a channel along which the blade passes. The length of the receptacle is sufficient to receive the blade. The top wall212has a hole216and the bottom wall has a hole217so as to again reduce material content. When the blade is in the receptacle the two components act to hold the rails16in a common straight line.

A locking mechanism22is provided, as best shown in the plan view ofFIG. 3, which acts to lock the blade201in the female receptacle211to hold the first and second elements together in a connected position. The locking mechanism22comprising a notch221formed in one side wall205of the blade201at a location on the first element immediately adjacent the cross member19. This notch cooperates with a projecting portion or finger222of the female coupling of the second element which is, in the connected position shown inFIG. 4, engaged into the notch to hold the blade against movement away from the second element.

The projecting portion or finger222is part of a rigid generally channel shaped member defined by two side portions223and226and a cross bar225. This member is carried by a flexible mounting member or arm224on one side of the female coupling21and on the other side by a symmetrical flexible mounting member or arm227. The channel shaped portion is thus held at the front of the female receptacle but can flex side to side by flexing of the arms224,227. This flexing action causes the projecting portion222to move in a direction away from the side surface of the blade201out of the notch221to allow the blade to move out of the female receptacle;

The female coupling21also includes a manually depressible member defined by the portion226on a side of the female receptacle opposite the projecting portion222which when depressed toward the female receptacle causes the finger222to move out of the notch.

The female coupling also includes the bar225which acts as a connecting portion connecting the manually depressible member226to the projecting portion222on the support223so that the motion of the manually depressible member226causes the finger to move out of the notch.

As shown best inFIG. 2, the connecting portion or bar225extends underneath the blade201and the bar is connected to the female receptacle211on each side of the blade201by a respective one of a pair of flexible arm portions224,227with each of the flexible arm portions extending alongside a respective one of the side walls of the female receptacle211. As best shown inFIG. 3, each of the flexible arm portions223,227is connected to said respective one of the side walls of the female receptacle211at its base and is inclined outwardly therefrom to the respective side. This structure resists upward and downward movement of the support bar225and the finger. Also this arrangement locates the top wall of the female receptacle so as to be is coplanar with the top surface of the rail and locates the bar extending across the blade from one side of the blade to the other with an upper surface in sliding contact with the blade.