WO2001032374A1

WO2001032374A1 - Constructional timber and methods and machinery for making same

Info

Publication number: WO2001032374A1
Application number: PCT/GB2000/004209
Authority: WO
Inventors: Mark Bradley Egerton; Jeffrey William Collinson
Original assignee: Target Waste Uk (Manchester) Limited
Priority date: 1999-11-05
Filing date: 2000-11-03
Publication date: 2001-05-10
Also published as: AU1157701A; GB9926164D0

Abstract

There is disclosed a combustible structional timer (11) comprising waste wood pieces (12), each trimmed to a uniform cross-section assembled into a larger, standard cross-sectional format, bonded together. There is also disclosed a combustible waste material reclaiming method comprising separating a supply of waste material into two parts, reclaiming the first part by an energy consuming procedure (91) and burning the second part (92) to generate power of said energy-consuming procedure.

Description

CONSTRUCTIONAL TIMBER AND METHODS AND MACHINERY

FOR MAKING SAME

This invention relates to constructional timber and methods and machinery for making same.

By constructional timber is meant timber for constructing building skeletons, such as joists, roof beams, purlins, ridge beams and the like, which presents in various "standard" - by which is meant popular, rather than conforming to officially or institutionally predetermined - sizes, such as may be commonly referred to as 2 x 4, 4 x 4 and the like in Imperial parlance, which might translate as 5cm x 10cm or 10cm x 10cm in metric units.

Such timbers are most often "whole" timbers, cut from solid trunk. Properly prepared and seasoned, they are by no means inexpensive, yet can exhibit defects which often render lengths unsuitable for specific constructional purposes, principally attributable to knots, special selection to avoid which leads to increased cost.

Despite its high cost, constructional timber is not a high value waste material, and the same is true of the wider range of wood found in buildings which is a waste product in demolition or refurbishment, window frame wood being typical. This usually presents in sizes too small for utilisation as wood, and is either burned (ecologically unfriendly) or chipped, for the manufacture of various board products, or sent to landfill.

The present invention provides constructional timber and methods and machinery for making the same which make effective use of waste wood. The invention, in one aspect, comprises constructional timber comprising waste wood pieces, each trimmed to a uniform cross-section assembled into a larger, standard cross-sectional format, bonded together.

The pieces may be each trimmed to the same uniform cross-section.

The pieces may be adhesively bonded together.

Facing surfaces may be plane or may be interlocking, as by a tongue and groove arrangement, formed in the trimming operation.

As the wood pieces are from waste woods, they will almost inevitably be of different lengths. This is turned to advantage in that the pieces will overlap lengthwise so that butt joints between lengthwise-adjacent pieces are staggered - this makes for a stronger arrangement.

The invention, in another aspect, comprises a method for making constructional timber, comprising the steps of

• selecting waste wood pieces

trimming the selected waste wood pieces to uniform cross-section

• assembling the waste wood pieces into a larger, standard cross- sectional format

bonding the wood pieces together in said standard format. The pieces may be of different lengths and butt joints between lengthwise- adjacent pieces staggered.

The method may be carried out continuously by joining leading ends of likewise-assembled pieces to trailing ends of earlier-assembled pieces, and cutting the bonded assembled pieces into lengths.

The invention also comprises machinery for making constructional timber from waste wood pieces, comprising

• trimming machinery for reducing waste wood pieces to uniform cross-section

• an assembly arrangement in which trimmed pieces from the trimming machinery are assembled into a larger, standard cross- sectional format

• a bonding arrangement in which the assembled pieces are bonded together.

The machinery may further comprise saw means for cutting bonded, assembled pieces into lengths.

The machinery may be adapted to operate continuously, assembling pieces of different lengths so that butt joints between lengthwise-adjacent pieces are staggered. The machinery may be laid out so that the pieces travel in a straight line from an assembly end, almost on an extrusion basis, to a cutting station at which the bonded, assembled pieces are cut to length.

The machinery may comprise an adaptive pressing device having pressure members deployable against trailing butt ends of an assembly of pieces which butt ends are in ragged formation to form staggered butt joints, the pressure members being presentable to the staggered butt ends by adjustment in a clamping member which, after adjustment, is operable to clamp them to be capable of applying lengthwise pressure on the butt ends.

The adaptive pressing device may comprise pistons in split bush members with pressure applying means to clamp the split bush members around the pistons thereby locking the pistons in the split bush members.

The pressure applying means may be fluid pressure operated or mechanically, e.g. spring operated.

The invention, in another aspect, comprises a method for reclaiming combustible waste material, comprising separating a supply of the waste material into two parts, reclaiming a first part by an energy-consuming procedure and burning a second part to generate power for said energy-consuming procedure.

The waste material may comprise wood, which may be reclaimed as constructional timber from waste wood pieces, each trimmed to a uniform cross-section, assembled into a larger, standard cross-section format, bonded together. The said second part of the waste material may be used to general electrical power, and may be used to generate heat and electrical power in a so-called combined heat and power system.

The division of the waste material may be effected on a variable ratio basis so as to meet varying requirements for reclaimed material and/or power.

Power generated from burning the waste material may be supplemented by power from another source when necessary. Power superfluous to requirements for said energy-consuming procedure may be supplied for external utilisation, as by feeding back (with suitable phase matching provision) into the national power grid.

Heat from burning the said second part of the waste may be used to dry or otherwise treat the said first part.

Embodiments of constructional timber and methods and machinery for making the same will now be described with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a short length of one form of the constructional timber;

Figure 2 is a cross-section of another form of the constructional timber;

Figure 3 is a cross-section of yet another form of constructional timber; Figure 4 is a diagrammatic illustration of a trimming operation on a piece of waste wood;

Figure 5 is a diagrammatic illustration of a bonding operation;

Figure 6 is a diagrammatic elevation of a production line for the constructional timber;

Figure 7 is a view of a 'ragged' end of a length of timber during a production process;

Figure 8 is a perspective view of an adaptive pressing device for use in the production of the constructional timber; and

Figure 9 is a diagrammatic illustration of a timber reclamation operation in conjunction with a combined head and power system.

Figure 1 to 3 illustrate constructional timber 1 1 comprising waste wood pieces 12, each trimmed to a uniform cross-section, assembled into a larger, standard cross-sectional format, bonded together.

In Figures 1 and 2, the waste wood pieces are each trimmed to the same uniform cross section, whereas in Figure 3 pieces of different cross section are used together.

The pieces 12 are adhesively bonded together . though in Figure 2, tongue and groove arrangements 13 are depicted which may give increased strength. Using modern adhesives, the bond is often stronger than the wood, and so the constructional timber 11 is at least as strong as a conventional 'solid' timber. The constructional timber of the invention may actually be stronger, as it is less likely to contain knots that extend over major parts of its cross-section. Knots 14 (Figure 1) will be, at any location along the timber 11, confined to one only of the pieces 12 that make up the timber.

Moreover, waste wood, e.g. from dismantled window frames and door surrounds, will be already seasoned and stable, so that the constructional timbers of the invention may be used directly after production without any further treatment or delay.

Figures 4 and 5 illustrate two stages in the production of timbers according to the invention. Figure 4 shows diagrammatically a trimming operation in which faces 15 are sliced off a piece of waste wood to leave the core 12 for use in the constructional timber. The faces 15 may be chipped for use in board, or may be disposed of to waste, there being substantially less waste than if the - otherwise largely unusable - window frame and like-sized pieces were disposed of altogether to waste.

Figure 5 diagrammatically depicts a clamping operation on the assembled pieces 12 in which mechanical or fluid pressure operated clamps 16 hold the pieces 12 together under pressure while the glue which has been applied between the mating faces hardens.

Figure 6 illustrates a production line for the constructional timber which comprises a trimming machine 17 performing on raw waste wood pieces the trimming operation depicted in Figure 5, and an assembly/gluing/pressure bonding station 18. Bonded, assembled constructional timber 11 from the station 18 passes on to a saw bench 19 at which it may be cut to desired lengths. The production is continuous, in the sense that as one length is moved off the station 18 on to the saw bench 19, fresh pieces 12 are assembled and glued to the trail end of the just-made timber.

As the trail end will be "ragged", as depicted in Figure 7, due to the fact that the pieces that made up the timber were of different lengths, the new pieces will overlap and there will be little or no distinction between an end and a centre portion of any timber length, so far as bonding is concerned.

To present the new pieces properly to the trail end of the just- made timber, a device 21 is used to push them into engagement. Of course, the trail end of the new assembly of pieces will be equally ragged, and the device 21, better illustrated in Figure 8, comprises a set of pistons 22, and for each piece 12, that are adjustable in a clamp arrangement 23 comprising blocks 24 with interblock grooves 25 in which the pistons are slidable. A mechanical or fluid pressure arrangement 24 clamps the pistons once properly adjusted.

Although glue has been proposed as a method of bonding the waste wood pieces together, other methods are not ruled out either as alternative or auxiliary methods. This, for example, nails or staples could be used, but it is desirable, perhaps, for most end uses not to include metal fastenings.

And, although the invention is primarily concerned with recycling wood, and, indeed, wood which, by virtue of its size and the presence of paint or other surface finishes, finds no other ready recycling application, the method is not necessarily restricted to wood. For example waste plastics material could be used, perhaps as a core element faced with wood on three or all four faces. It is not, either, necessary to trim the pieces into rectangular cross-section. Triangular or hexagonal cross-sections might be more suitable for some applications. And hollow constructional timbers could also be made.

As the constructional timber according to the invention could be considerably stronger than new "solid" timbers, smaller cross-sections might be used. Thus the cost of timbering might be reduced on two counts, namely the inherent low cost of the timber per se, and the fact that smaller sections are required.

Moreover, as the timber is in theory unrestricted as to lengths, larger and more complex structures - arches, perhaps - can be designed with less in situ jointing requirements.

Figure 9 illustrates a timber reclamation operation 91 in conjunction with a combined heat and power system 92.

Waste timber 93 for the reclamation operation is divided into two streams of which one is passed to the reclamation operation 91, which may be as described with reference to Figures 1 to 8, and the other is passed to the combined heat and power system 92, where it is burned to generate electricity which is supplied via line 94 to operate machine of the reclamation system 91 and heat which is supplied via ducting 95 to heat the reclamation plant and to provide heating for treating waste timber in the operation to adjust its moisture content, for example.

Electrical power superfluous to requirements for the reclamation operation can be fed into a public supply network, with suitable phase matching provision, as is known for combined heat and power technology, via line 96, and superfluous heat can be supplied via ducting 97 to a neighbourhood heating scheme, for example. Such an arrangements can burn wood efficiently with a "clean" output. Burning timber is not eco-unfriendly, as although it yields carbon dioxide, which is a "greenhouse" gas, that is recycled in the growth of new timber - it is only fossil fuels which as to the atmospheric carbon burden.

The timber can be divided for example, 60% for reclamation, 40% for burning, but the ratio might be varied, for example, if there is an increased demand for reclaimed timber, a higher proportion may be sent through the reclamation procedure. If the reduced amount burned results in a shortfall of power, this may be made up from the public supply network. On the other hand, if there is a slacker demand for the timber product, more waste can be burned to generate head and/or power. In this way the timber need not go to landfill, nor be burned inefficiently and under conditions in which emissions contain harmful and eco-unfriendly products.

Claims

1. Constructional timber comprising waste wood pieces, each trimmed to a uniform cross-section assembled into a larger, standard cross-sectional format, bonded together.

2. Constructional timber according to claim 1, in which the pieces are end trimmed to the same uniform cross-section.

3. Constructional timber according to claim 1 or claim 2, in which the pieces are adhesively bonded together.

4. Constructional timber according to any one of claims 1 to 3, in which the pieces overlap lengthwise so that butt joints between lengthwise-adjacent pieces are staggered.

5. A method for making constructional timber, comprising the steps of

• selecting waste wood pieces

• trimming the selected waste wood pieces to uniform cross-section

assembling the waste wood pieces into a larger, standard cross- sectional format

• bonding the wood pieces together in said standard format.

6. A method according to claim 5, in which the wood pieces are of different lengths and butt joints between lengthwise and adjacent pieces are staggered.

7. A method according to claim 5 or claim 6, carried out continuously by joining leading ends of likewise-assembled wood pieces to trailing ends of earlier- assembled woods, and, cutting the bonded, assembled pieces into lengths.

8. Machinery for making constructional timber from waste wood pieces comprising

• trimming machinery for reducing waste wood pieces to uniform cross-section

a bonding arrangement in which the assembled pieces are bonded together.

9. Machinery according to claim 8, further comprising saw means for cutting bonded, assembled pieces into lengths.

10. Machinery according to claim 8 or claim 9, adapted to operate continuously, assembling pieces of different lengths so that butt joints between lengthwise-adjacent woods are staggered.

11. Machinery according to any one of claims 8 to 10, comprising an adaptive pressing device having pressure members deployable against trailing butt ends of an assembly of pieces which butt ends are in ragged formation to form staggered butt joints, the pressure members being presentable to the staggered butt ends by adjustment in a clamping member which, after adjustment, is operable to clamp them to be capable of applying lengthwise pressure on the butt ends.

12. Machinery according to claim 11, in which the adaptive pressing device comprises pistons in split bush member with pressure applying means to clamp the split bush members around the pistons thereby locking the pistons in the split bush members.

13. Machinery according to claim 12, in which the pressure applying means are fluid-operated.

14. Machinery according to claim 12, in which the pressure applying means are mechanically e.g. spring operated.

15. A method for reclaiming combustible waste material, comprising separating a supply of the waste material into two parts, reclaiming a first part by an energy- consuming procedure and burning a second part to generate power for said energy- consuming procedure.

16. A method according to claim 15, in which the waste material comprises wood.

17. A method according to claim 16, in which the wood is reclaimed as constructional timber from waste wood pieces, each trimmed to a uniform cross-section, assembled into a larger standard cross-sectional format, bonded together.

18. A method according to any one of claims 15 to 17, in which the second part is used to generate electrical power.

19. A method according to claim 18, in which the second part is used to generate heat and electrical power in a so-called combined heat and power system.

20. A method according to any one of claims 15 to 19, in which the division of the waste material is effected on a variable ratio basis so as to meet varying requirements for reclaimed material and/or power.

21. A method according to claim 20, in which power generated from burning the waste material is supplemented by power from an external source when necessary.

22. A method according to claim 20 or claim 21, in which power generated from burning the waste material superfluous to requirements for said energy-consuming procedure is supplied for external utilisation.

23. A method according to claim 23, in which power is supplied to a network.

24. A method according to any one of claims 15 to 23, in which heat from burning the said second part of the waste is used to dry or otherwise treat the said first part.