GB2290046A

GB2290046A - Support board

Info

Publication number: GB2290046A
Application number: GB9511190A
Authority: GB
Inventors: Daniel Bugajny
Original assignee: JAN CONSTRUCT NV
Current assignee: JAN CONSTRUCT NV
Priority date: 1994-06-07
Filing date: 1995-06-02
Publication date: 1995-12-13
Anticipated expiration: 2015-06-02
Also published as: DE19519661A1; NL1000461C2; GB9511190D0; DE19519661C2; NL1000461A1; BE1009036A3; GB2290046B

Description

2290046 1 Support Board.

The invention concerns a support board, especially of the type used in the manufacture of concrete objects, which support board comprises a number of wooden beams which are placed with their lateral edges against each other, and tension rods which are placed crosswise to the longitudinal direction of the beams and parallel to the plane of the support board, crosswise through these beams in order to hold these beams against each other.

Such support boards are used as a base whereupon concrete objects, such as tiles or stones, can be manufactured.

These support boards are placed upon a vibration plate and an open mould is placed thereupon and filled with concrete. After a short vibration time, the open mould is removed, and the support boards with the still wet con- - crete objects are removed from the table. The concrete 20 objects remain on the support boards until they are hardened and dried.

With known support boards of the said sort, the beams are not only held together by means of tension rods, but also by means of profile strips which are put over the ends of the beams and are fixed at each of the beams by means of rivet nails or rivets. The tension rods have a threaded end provided with thread and a nut which is screwed upon it for the adjustment of the useful length.

It is clear that, due to the filling of the concrete and the subsequent hardening and drying of the concrete objects, the degree of humidity in the wood is changing permanently, which results in a permanently alternating expansion and shrinkage of the beams. If, as a result of 2 shrinkage, the gaps between the beams become too large, so that concrete may drop in between, the beams are clamped together again by tightening the bolts of the tension rods. Because the beams are also fixed with their ends to the profile strips and, thus, cannot expand and shrink freely, relatively large stresses are caused at the place of the rivet nails or rivets, and the beams will crack. After tightening of the boltsF the tension rods prevent an eventual expansion of the beams, such that the beams, when getting wet and expanding, will twist.

The invention aims to remedy these disadvantages and to provide a support board in which the beans can expand and shrink freely as a result of humidity variations, but where they always remain pressed against each other nicely.

This aim is realized according to the invention in that the tension rods are resilient and clamp the beams against each other with a spring tension.

In a special form of embodiment of the invention, at least one end of each tension rod is provided with a spring, by means of which it presses against an outmost beam of the support board.

In a preferredly used form of embodiment of the invention, the spring tension of each tension rod can be adju- sted.

To this end, each tension rod can have an actual rod which, at least at one end, is provided with thread and a nut which is screwed onto this end, while a spring is mounted between this nut and an outmost beam.

0 v 3 This nut and a spring are preferably sunk into a recess in this outmost beam.

In an expedient form of embodiment of the invention, the beams, at one lateral edge which is pressed against an adjacent beam, are provided in their longitudinal direction and between the two sides of the support board with a recess, such, that at opposite sides of the tension rod, they are in contact with each other only by edges.

Due to the recess, the contact surface between the adjacent beams is smaller and the pressure of the beams onto each other per surf ace unit is larger, as a result of which the stiffness or bending resistance is enlarged.

At the support board according to the invention, at the eventually smaller ends of the beams, profile strips can also be attached, but each of these prof ile strips is fixed to only one of the beams, while the other beams can shift freely crosswise to their longitudinal direction in reference to these profile strips.

These prof ile strips, which extend over the total width of the support boards, enlarge the slErength against bending.

These profile strips preferably have U-shaped section, the outmost edges of the legs of which are bent inclined towards each other and arranged in grooves in both sides of the support board.

With the purpose of better showing the characteristics of the invention, several preferred forms of embodiment of a support board according to the invention are described in the following as examples without any limitative character, referring to the enclosed drawings, wherein:

4 f igure 1 shows a top view of a support board accor- ding to the invention; figure 2 shows a cross section according to the line II-II in figure 1; figure 3 shows a cross section according to the line III-III in figure 2, drawn at a larger scale; figure 4 shows, at a larger scale, the part which is indicated by F4 in figure 2; f igure 5 shows the part from f igure 4, but in ref erence to another form of embodiment of the invention.

The support board shown in the figures 1 to 4 consists of a number of wooden beams 1 which are clamped against each other with their lateral edges by means of three connecting rods 2, whilst metal prof ile strips 3 are arranged over the ends of beams 1.

The beams 1 are planed and manufactured from hard or soft wood with a moisture content between 15 and 40%. The most usual wood is oak or pine.

The tension rods 2 each consist of an actual rod 4, both ends of which are threaded, and two nuts 5 being screwed onto these ends. One of the ends of rod 4 is surrounded by a spring 6, namely a coil spring, which is arranged between a nut 5 and an outmost beam 1. At both ends of the spring 6, a ring 7 is attached f or distribution of the pressure, whilst at the opposite end between the nut 5 and the wood of the outmost beam 1, a ring 7 is attached as well.

Each of the tension rods 2 extends crosswise through the beams 1, perpendicular upon their longitudinal direction and parallel to the practically even sides of the support boards. Both threaded ends and, thus, the nuts 5 and rings 7 and, at one end, the spring 6, too, are sunk into recesses 8 in the outmost beams 1.

In order to prevent that dirt impairs the resilient function of the spring 6, this spring 6 is also surrounded by a sleeve 9 which is arranged in the recess 8 and is shor- ter than the length of the coil spring 6 at normal moisture contents, this means, when the support board is practically dry. In this normal condition, the spring 6 is pre-tensioned, this means, partially, but not totally pressed together, so that the beams 1 actually can be pressed against each other under tension, but still can extend or shrink even more eventually.

The pressure with which the beams 1 are pressed against each other is determined by the tension of the spring 6 and can be regulated by turning the nut 5.

The beams 1 are in their longitudinal direction and between both sides of the support board, at one of their lateral sides which is pressed against an adjacent beam 1, provided with a recess 10, such that they contact each - other at opposite sides of the tension rods 2 only- by edges. By means of this recess 10, the contact surface - between adjacent beams 1 is smaller. The pressure per surface unit of the beams 1 onto each other and, conse- quently, the stiffness or bending resistance increase.

The ends of the beams 1 are, as shown in figure 4, somewhat less thick than the rest, and over these ends of all the beams 1, a metal profile strip 3 is attached. Consequently, such a profile strip extends onto both edges of the support board which are directed crosswise to the 6 longitudinal direction of the beams 1. This profile strip 3 comprises a Ushaped section, whereby the edges of the legs of which are bent inclined towards each other and away from the bottom of the U. The U-shape matches around the smaller ends of the beams 1, whilst the bent edges of the legs slideably fit into the corresponding grooves 11, which are arranged directly next to the tapering ends in the beams 1 at both sides of the support beam.

The two profile strips 3 each are attached at the ends of one beam, namely the center bean 1, by means of a rivet nail 12.

In f igure 5, a variation of the support board is shown which only dif f ers from the aforegoing described support board because the ends of the beans 1 are not tapered and the profile strips 3 comprise a U-shaped section whereby both legs are directed inclined towards each other from the bottom. These legs shiftably f it into corresponding grooves 11 which are arranged in the ends of the beams 1.

The profile strips 3 increase the bending resistance but do not prevent the extension or shrinkage of the beams 1. By means of the springs 6, the beams 1 are always pressed against each other with an adjustable force, so that they connect nicely with their lateral edges against each other. Nevertheless, the extension of the beams is still possible. Consequently, both sides of the support board remain totally flat, even after longer usage.

Consequently, these support boards are especially useful for the formation of concrete objects thereupon.

Of course it is not necessary that the ends of the tensi on rods are sunk. It is neither necessary that a nut is arranged at each end of the tension rods. The tension 7 rods might be provided with a thickened head at one end.

The number of tension rods must also not necessarily be three. Two is sufficient.

8

Claims

Claims.

1. - Support board, especially of the type used in the manufacture of concrete objects, which support board comprises a number of wooden beams (1) which are placed with their lateral edges against each other, and tension rods (2) which are placed crosswise to the longitudinal direction of the beams (1) and parallel to the plane of the support board, crosswise through these beams (1) in order to hold these beams (1) against each other, characterized in that the tension rods (2) are resilient and clamp the beams (1) with a spring tension against each other.

2. - Support board according to the previous claim, characterized in that at least one end of each tension rod (2) is provided with a spring (6) by means of which it presses against an outmost beam (1) of the support board.

3. - Support board according to any one of the claims 1 and 2, characterized in that the spring tension of each tension rod (2) is adjustable.

4.- Support board according to claim 3, characterized in that each tension rod (2) comprises an actual rod (4) which, at least at one end, is provided with a thread, and a nut (5) screwed onto this end, whilst a spring (6) is arranged between this nut (5) and an outmost beam (1).

5.- Support board according claim 4, characterized in that this nut (5) and spring (6) are sunk into a recess (8) in this outmost beam (1).

6. - Support board according to any one of the claims 4 and 5, characterized in that the actual rod (4) is provi- 1k 1 9 ded with a thread at both ends and carries a nut (5).

7.- Support board according to one of the previous claims, characterized in that the beams (1), at a side which is pressed against an adjacent beam, are provided in their longitudinal direction and between the two sides of the support board with a recess (10), such, that they contact each other only at opposite sides of the tension rods (4) only by edges.

8.- Support board according to any one of the previous claims, characterized in that profile strips (3) are arranged at the ends of the beams (1), which are each fixed only at one of the beams (1), whilst the other beams (1) can shift freely crosswise to their longitudinal direction in reference to these profile strips (3).

9.- Support board according to claim 8, characterized in that these profile strips (3) comprise a U-shaped section whereby the outmost edges of the legs are bent inclined towards each other and are arranged in grooves (11) in both sides of the support board.

10.- Support board according to claim 8, characterized in that these profile strips (3) comprise a U-shaped section the legs of which are bent inclined towards each other from the bottom and which are arranged in grooves (11) in the ends of the beams (1) at both sides of the support beam.

11. Support board substantially as herein described with reference to, or with reference to and as illustrated in, the accompanying drawings.