BACKGROUND OF THE INVENTION

1) Field of the Invention The present invention relates to a support for an internally threaded ferrule to be incorporated into a concrete component during casting.

2) Description of the Prior Art

Internally threaded ferrules are incorporated into panels and other concrete components to provide a cast-in fixing point for subsequent attachment. Typically, the ferrule is mounted to a support, sometimes known as a chair, which rests on the casting base and positions the open end of the ferrule at the correct height so that it opens onto a face of the component being cast. Conventionally, the ferrule includes at its lower end a transverse passage through which extends a cross bar which is tied into reinforcement of the component. Ferrules are normally available in two types. One includes at its lower end an enlarged base or foot portion which provides stable support for the ferrule when resting on that base and chairs for use with that type of ferrule have a support surface on which the foot portion rests. The other type of ferrule does not include that feature and is of constant outer diameter over its entire length. For this type of ferrule (referred to hereafter as a round bar ferrule) the chair is configured so that support for the ferrule is provided by the cross bar which is engaged in seats in the chair, there being no direct supporting engagement between the chair and the ferrule itself. Conventionally, different types of chair are provided for these different types of ferrule.

For the round bar ferrule, the cross bar serves not only to locate the outer end of the ferrule at the correct height it also acts as the primary anchorage for the ferrule within the concrete. The general practice is to tack weld the cross bar to the ferrule to ensure that the ferrule cannot slide laterally along the cross bar and also to ensure that the cross bar is positioned at the bottom of the transverse passage through the ferrule so that when the ferrule is under load the ferrule does not slip as a result of clearance between the cross bar and passage as may occur if the top part of the passage is resting on the cross bar.

For the footed ferrule, while the cross bar contributes to the anchorage of the ferrule within the concrete, the anchorage is substantially provided by the enlarged foot portion and the primary purpose of the cross bar in that case is to ensure the correct lateral location of the ferrule, for which purpose the ferrule is either tied to the cross bar using a wire tie to prevent slippage along the cross bar prior to casting or alternatively it may be tack welded to the cross bar for the same purpose.

Ferrule cross bars have traditionally been provided in two sizes, 10mm and 12mm diameter. The 12mm bars are normally used with round bar ferrules where the bar provides the anchorage of the ferrule within the concrete whereas the 10mm bars are normally used with footed anchors where its principal effect is for lateral location of the ferrule rather than anchorage. However notwithstanding industry practice to use 12mm cross bars with round bar ferrules, the present inventor has determined the smaller diameter 10mm cross bars would quite adequately perform an effective anchoring function.

SUMMARY QF THE INVENTION

The invention in its preferred embodiment provides a ferrule support or chair for use with both types of ferrule, round bar or footed, and the relationship between the chair and ferrule is such that the chair causes the ferrule to be locked to the cross bar without the need to weld or wire the ferrule to the cross bar.

According to the invention there is provided a support for an internally threaded ferrule to be cast into a concrete product such as a panel, the support being engageable with a casting bed and comprising a ferrule support surface for supporting the base of a ferrule above the casting bed, the ferrule having within its base part a transverse passage for a cross bar for co-operation with reinforcement, the support further comprising clips engageable with the cross bar to anchor the cross bar, wherein the configuration of the clips in relation to the ferrule support surface of the support, the ferrule and its cross bar is such that when the cross bar is engaged with the clips, the cross bar applies to the ferrule a downward force to force the base of the ferrule into tight engagement with the support so as to engender factional locking between the ferrule and its cross bar sufficient to prevent slippage of the ferrule relative to the cross bar.

Advantageously, clips are engageable with cross bars of different diameter whereby to provide the frictional locking effect when the ferrule is used with cross bars of different predetermined diameters.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a perspective view of a ferrule chair in accordance with preferred embodiment of the invention;

Figures 2 and 3 show successive stages in the engagement of a ferrule with the chair;

Figure 4 illustrates schematically the engagement action between a clip of the chair and a smaller diameter cross bar of the ferrule; and

Figure 5 illustrates schematically the engagement action between a larger diameter cross bar and the clip to thereby permit the same ferrule and chair to be used selectively with cross bars of different diameter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The ferrule chair in accordance with the preferred embodiment of the invention is designed for use with both round bar ferrules and footed ferrules and avoids the need to tack weld the ferrule to the cross bar (in the case of round bar ferrules) or tack weld or tie the ferrule to the cross bar (in case of footed ferrules). This effect is achieved by an interlocking relationship between the ferrule, cross bar and chair which ensures that when the ferrule and cross bar are engaged with the chair, the ferrule is friction-locked against movement on the cross bar.

The chair shown in the accompanying drawings comprises an array of legs 2 projecting downwardly from upper support structure 4 having a substantially flat base 6 configured to support an internally threaded ferrule either of round bar type or footed type by engagement with the underside of the ferrule base. Figures 1 to 3 show the chair used with a footed ferrule 8, but its action with a round bar ferrule is identical. The chair has integral clips 10 which are engageable with a cross bar 12, which may simply be a length of reinforcing bar, extending through the transverse passage through the base part of the ferrule. The centre of the base 6 of the support structure 4 has a small upwards projection 14 engageable within a small dimple or recess within the underside of the ferrule base to ensure central location between the ferrule and chair.

There is a critical dimensional relationship between the clips 10, the support base 6, the diameter of the cross bar 12, and the distance between the lower edge of the transverse passage through the ferrule and the base of the ferrule such that when the cross bar 12 is engaged with the clips 10, the clips will apply a downwards force to the cross bar 12 which forces, by interaction between the lower periphery of the cross bar and the lower periphery of the transverse passage, the ferrule downwardly so that its base is in tight engagement with the support base 6 of the chair, the frictional forces engendered by the engagement between the cross bar and ferrule being such as to prevent displacement of the ferrule along the cross bar. The same effect is achieved whether the ferrule is a round bar ferrule or a footed ferrule and as a result of this action it is not necessary to weld or tie the ferrule to the cross bar to prevent its slippage along the cross bar prior to casting. Moreover, in the case of a round bar ferrule, as its base is now supported by the support base of the chair, its upper end will always be supported by the chair at the correct height and, despite clearance between the cross bar and passage, slippage of the ferrule under load will not occur as the cross bar, which as mentioned earlier acts to anchor the ferrule, is held in tight engagement with the lower periphery of the passage. It will be appreciated from the above that round bar and footed ferrules for use with the same chair will be produced so that the lower edge of their transverse passages are spaced at the same distance above the underside of the ferrule.

The clips 10 have opposed resilient jaws with inwardly directed teeth 10a at their outer ends to lock over the cross bar when the bar is pushed downwardly between the jaws so as to apply downwards force between the bar and ferrule. The required dimensional relationships between the clips, cross bar, transverse passage in the ferrule and base of the ferrule, and support base of the chair can readily be determined empirically to achieve the required friction locking effect for given round bar and footed ferrules when used with a given diameter of cross bar. Although as previously indicated it is considered that use of the smaller 1 Omm diameter cross bar will be adequate for not only footed ferrules but also round bar ferrules, nevertheless some people in the industry may prefer to continue to use the larger 12mm diameter cross bars notwithstanding the increased material cost related to that and for this reason the round bar ferrule can be produced with a transverse passage of a diameter sufficient to receive the larger bar (although its lower edge will still be spaced at the same distance above the underside of the ferrule base). To accommodate this, the clips 10 are designed to operate equally effectively when engaging either a 10mm bar or a 12mm bar. Figure 4 illustrates the action of the clip with a smaller (10mm) cross bar and Figure 5 illustrates the action with a larger (12mm) cross bar, the difference between the two solely being the part of the bar engaged by the teeth 10a of the jaws; these Figures illustrate the action in relation to a round bar ferrule with its transverse passage sized to receive both the smaller and larger cross bars.

The embodiment has been described by way of example only and modifications are possible within the scope of the invention. For example the general configuration of the chair in terms of its array of legs may differ from that shown or other structure may be provided to position the support base of the chair from the casting base, and the clips may take a different form to those shown.