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Title:
METHOD FOR MANUFACTURING A PREFABRICATED BUILDING ELEMENT
Document Type and Number:
WIPO Patent Application WO/2015/087223
Kind Code:
A1
Abstract:
The present invention relates to method for manufacturing a building element. The method comprising the steps of peeling a log in a lathe to form a veneer; forming the veneer to a veneer sheet (1) of a suitable size; impregnation of the veneer sheet, wherein impregnation chemicals is applied on both sides (2, 3) of the veneer sheet;drying the veneer sheet (1); applying glue (10) on at least one side of the veneer sheet (1); pressing a predetermined number of glued veneer sheets together to form a billet (4) in a pressing stage; trimming the edges of the billet (4), such that the billet is square formed; hot pressing the billet (4) for 10-90 minutes; applying glue (11) on at least one side of the billet; cold pressing a predetermined number of glued billets together to form a building element, and trimming the edges of the building element, such that the building element is square formed.

Inventors:
KALLIO MIKA (FI)
Application Number:
PCT/IB2014/066643
Publication Date:
June 18, 2015
Filing Date:
December 05, 2014
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
STORA ENSO OYJ (FI)
International Classes:
B27D1/04; B27D1/10; B32B21/13; B32B21/14; E04C2/12
Domestic Patent References:
WO1997037821A11997-10-16
WO1997038187A11997-10-16
Foreign References:
NL1021153C22004-01-27
DE3243497A11983-07-14
US3687773A1972-08-29
DE20017058U12001-06-28
US6319585B12001-11-20
US6444079B12002-09-03
US20070163194A12007-07-19
Other References:
See also references of EP 3079869A4
Attorney, Agent or Firm:
MAGNUSSON, Ulf (Group IPBox 9090, Karlstad, SE)
Download PDF:
Claims:
C L A I M S

1. Method for manufacturing a prefabricated building element, characterized in that the method comprising the steps of:

- peeling a log in a lathe to form a veneer, wherein the thickness of the veneer is in the range from about 2.5 mm up to about 5 mm,

- forming the veneer to a veneer sheet (1) of a suitable size, wherein the veneer sheet (1) has a first side (2) and a second side (3),

- drying the veneer sheet (1),

- applying glue (10) on at least one side (2, 3) of the veneer sheet (1), preferably by the aid of a spreader, - pressing a predetermined number of glued veneer sheets together to form a billet (4) in a pressing stage, wherein the billet has a first side (5) and a second side (6) which facing away from the first side,

- trimming the edges of the billet (4), such that the billet is square formed,

- hot pressing the billet (4) for 10-90 minutes,

- applying glue (11) on at least one side of the billet (4), preferably by the aid of a spreader,

- cold pressing a predetermined number of glued billets together to form a building element (7, 14), the building element (7, 14) has a thickness from about 80 mm to about 400 mm, and

- trimming the edges of the building element (7, 14), such that the building element (7, 14) is square formed.

2. Method according to claim 1, characterized in that the method further comprising a step of impregnation of the veneer sheet (1), wherein at least one impregnation chemical is applied on both sides (2, 3) of the veneer sheet (1) and that the sides (2, 3) are rolled after application to enhance the penetration of the chemical and to remove unnecessary chemicals from the veneer sheet (1) , 3. Method according to claim 2, characterized in that the impregnation is performed by spraying, wherein the spraying station is stationary and the veneer sheet (1) is transported through the spraying station. 4. Method according to any of claims 1-3, characterized in that the building element (7) comprising several layers of billets (4), wherein each layer is formed by several billets (4) with a smaller areal surface than the areal surface of the layer.

5. Method according to any of claims 1-4, characterized in that the method further comprising a step of treating the building element (7, 14) in a CNC machine to form the final shape of the building element (7, 14) .

6. Method according to claim 5, characterized in that the formed building element (7, 14) is an external wall having recesses (12, 13) 7. Method according to any of claims 1-6, characterized in that the method further comprising the step of placing at least two adjacent billets (4) to be mutually offset relative each other in the longitudinal direction, such that a female/male member (15) is formed at at least one of the end portions of the building element (14) for longitudinal connection to an adjacent building element (14) .

8. Building element (7, 14), characterized in that the building element (7, 14) is manufactured by the method of claims 1-7. 9. Building element (7) according to claim 8,

characterized in that the building element (7) is an external wall (8) .

10. Building element according to claim 8, characterized in that the building element (14) can be connected together in their longitudinal direction to form an external wall (8) .

Description:
METHOD FOR MANUFACTURING A PREFABRICATED BUILDING ELEMENT

The present invention relates to a method for

manufacturing a prefabricated building element.

The present invention further relates to a prefabricated building element.

It is well known that boards of cross-laminated timber (CLT) are suitable for use as prefabricated elements in building constructions. A CLT board is a massive wood building material consisting of bonded, cross-laminated single layers called lamellas. The layers vary in

thickness and can number 3, 5, 7 or more. Formaldehyde- free and environmentally friendly adhesives are normally employed for bonding. The cross structure of CLT

components guarantees integral stability. The CLT board may be manufactured in large dimensions, such as, 2.95 x 16 m with a thickness up to 40 cm. This enables fast construction and minimizes the butt joints between the boards. A good performance in static and physical

properties makes CLT possible to be used as a material for intermediate flooring in houses, roof structure for large halls, external walls, internal walls, ceilings and roofs. Moreover, it is possible to produce CLT elements from the CLT boards by installing insulation, exterior cladding, windows and doors in the boards, depending on the needs. With CLT boards and elements, the frame for a detached house can even be erected in just one day.

It is an object with the present invention to provide an alternative prefabricated building element which is manufactured in a more economical way in comparison to the above mentioned prefabricated building element of CLT . This new kind of building element can replace the building element of CLT.

The method according to the invention is characterized in that the method comprising the steps of:

- peeling a log in a lathe to form a veneer, wherein the thickness of the veneer is in the range from about 2.5 mm up to about 5 mm,

- forming the veneer to a veneer sheet of a suitable size, wherein the veneer sheet has a first side and a second side,

- drying the veneer sheet,

- applying glue on at least one side of the veneer sheet, preferably by the aid of a spreader,

- pressing a predetermined number of glued veneer sheets together to form a billet in a pressing stage, wherein the billet has a first side and a second side which facing away from the first side,

- trimming the edges of the billet, such that the billet is square formed,

- hot pressing the billet for 10-90 minutes,

- applying glue on at least one side of the billet, preferably by the aid of a curtain spreader,

- cold pressing a predetermined number of glued billets together to form a building element, the building element has a thickness from about 80 mm to about 400 mm, and

- trimming the edges of the building element, such that the building element is square formed.

The building element according to the invention is characterized in that it is manufactured by the method above . In the following, the invention will be described further with reference to the drawings, wherein

Figure 1 shows a side view of a veneer sheet. Figure 2 shows a side view of a billet comprising layers of several veneer sheets.

Figure 3 shows a side view of a building element

comprising layers of several billets.

Figure 4 shows a building element in three views, wherein the building element comprising layers of several billets and wherein each layer is formed by several smaller billets .

Figure 5 shows a building element in three views, wherein the building element comprising layers of several billets and wherein each layer is formed by several smaller billets . Figure 6 shows a building element of an external wall to a house.

Figure 7 shows a second embodiment of the invention where the building element comprises two billets which are mutually offset relative each other in the longitudinal direction .

Figure 8 shows the second embodiment of the invention where the building element comprises three billets which are mutually offset relative each other in the

longitudinal direction. Note that the drawings in Figure 1-8 are not to scale.

The present disclosure is generally directed to a method for manufacturing a prefabricated building element which is intended to be used as intermediate flooring in houses, external walls, internal walls, ceilings, roofs etc. In this disclosure, the term "building element" is used to refer to a range of derivate wood products which are manufactured by binding together veneers. The term "wood" is used to refer to any cellulosic material. The term "veneer" is used herein to thin pieces of material derived from wood.

In the following description of the invention the

expression "cold pressing" will be frequently used. It is understood, however, that this expression is quite general and include several different methods to achieve the necessary pressure when pressing glued surfaces together. For example may "cold pressing" be performed by mechanical pressing, by using screws, by using nails or by vacuum pressing.

The method, in accordance with the invention, feeds sawed wood logs to a lathe. The lathe 2 peels the logs into veneers. The thickness of the peeled veneer is typically about 3.5 mm, but can be in the range from 2.5 mm up to 5 mm.

The veneers are then clipped in a clipping machine to a form a veneer sheet 1 of a desirable size. Additionally, smaller veneer pieces can be composed to a desirable size of the veneer sheet 1 by bonding two or more pieces together. The veneer sheet 1 may have a width (W) from about 1.5 m up to about 3.5 m and a length (L) from about 6 m up to about 20 m. The veneer sheet 1 has a first side 2 which faces upwards and a second side 3 which faces downwards and away from the first side 2.

The next step is an, optional, impregnation step where impregnation chemicals are applied onto both sides 2, 3 of the veneer sheet 1. The veneer sheet 1 is preferably transported through a spraying station where both sides 2, 3 of the veneer sheet 1 is sprayed with impregnation chemicals in order to withstand moisture. After spraying, the sprayed sides 2, 3 are rolled by at least one roller in order to further penetrate the chemicals into the veneer sheet 1 and to remove unnecessary chemicals from the veneer sheet 1. The spraying and rolling penetrates the veneer sheet 1 up to 2.5 mm, which result in a fully impregnated veneer sheet 1 with a thickness of 5 mm. The line speed of the veneer sheet 1 during the spraying step is about 1 m/s up to 10 m/s. This step may also include flame retardants chemicals together with the impregnation chemicals .

The spraying step may be replaced with a dipping step where the veneer sheet 1 is dipped into a bath comprises the impregnation chemicals. The subsequent rolling is the same as for the spraying step.

However, a major benefit with the on-line spraying and rolling is that it is possible to control the moisture content of the veneer sheet 1. It is also much faster than if the chemicals were treated with dipping or similar . The next step is to dry the veneer sheet 1 such that a humidity level in the veneer sheet 1 is decreased to a predetermined maximum level. The temperature and time of the drying step is depending on the current humidity level in the veneer sheet 1 and the wood species.

After drying at least one side 2, 3 of the veneer sheet 1 is applied with a layer of glue 10. The glue is

preferably applied on the veneer sheet 1 by a curtain spreader or similar, where the spreader is stationary and the veneer sheet 1 is moving through the spreader.

Several glued veneer sheets are then pressed together in a pre-pressing step. The first side 2 of a veneer sheet is facing against the second side 3 of an adjacent veneer sheet, such that the veneer sheets form a billet 4, which comprising a first side 5 and a second side 6 which faces away from the first side 5. The pressing time is

depending on the thickness of the billet 4, the type of glue and the pressure. The billet 4 may have a thickness from 25 mm up to 100 mm.

The billet 4 is then processed in an edge trimming step, where the edges of the billet 4 are trimmed, such that the billet 4 become square formed.

The billet 4 is then treated in a hot pressing step. The hot pressing step presses billet together even further. The pressing time may be about 10-90 minutes depending on the process parameters such as billet thickness,

temperature of the pressing elements, pressure etc. The billet 4 is then transported to a gluing station. At least one side of the billet 4 is applied with a layer of glue 11. The glue 11 is preferably applied on the billet 4 by a curtain spreader or similar, where the spreader is stationary and the billet 4 is moving through the

spreader .

A predetermined number of glued billets 4 are then pressed together in a cold pressing step. The first side 5 a billet is facing against the second side 5 of an adjacent billet, such that the billets form a building element 7, 14, which comprising a first side 8 and a second side 9 which faces away from the first side 8. The pressing time may be about 25-90 minutes depending on the process parameters such as the thickness of the building element 7, 14, pressure or type of glue. The building element 7, 14 may have a thickness from about 80 mm up to about 400 mm. Figure 4 and figure 5 shows a preferred embodiment of the building element 7. The building element 7 comprising two layers of billets 4, wherein each layer is formed by several billets 4 with a smaller areal surface than the areal surface of the layer and the areal surface of the building element.

The building element 7, 14 is then processed in an edge trimming step, where the edges of the building element 7, 14 are trimmed, such that the building element 7, 14 become square formed.

The glue line 10, 11 after the pressing steps has a thickness of about 0.1-0.3 mm. If a hot press is used, the glue is normally based on melamine. If only cold presses are used the glue is normally based with

polyurethane . However, both glues can be mixed in various ways to optimize the process parameters. The veneer sheets are compressed during the pressing steps. For example, a veneer sheet of 3.5 mm has after the pressing steps a thickness about 3.2 mm.

A final, optional, step is a CNC treatment to form a final shape of the building element. Figure 3 shows a CNC treated building element 7, 14 which is an external wall 7, where recesses for a window 12 and a door 13 has been made. The dimensions of the end product can be customized quite flexible to meet customer demands, a preferred length (L) of the building element may be up to 20 m and the height (W) (i.e. the width of the building element) is up to 3.5 m.

In the foregoing, the invention has been described on the basis of a first embodiment. It is appreciated, however, that other embodiments and variants are possible within the scope of the following claims.

For example, figure 7 and figure 8 discloses a second embodiment of the invention wherein at least one of the end portions of the building element 14 is equipped with a male/female member 15 for longitudinal connection to an adjacent building element 14. Moreover, the length (L) of this building element 14 is shorter in comparison to the building element 7 of the first embodiment. The length (L) and the width (W) of this building element 14 are both preferably in the range from about 1.5 m to about 3.5 m. The veneer sheets 1 for forming a billet 4 having a much shorter length in comparison to a veneer sheet of first embodiment. This veneer sheet 1 may have length from about 1.5 m to about 3.5 m. Other dimensions of the veneer sheet 1, such as thickness and width, are equal as for a veneer sheet of the first embodiment.

All other method steps, such as clipping, trimming, impregnation, drying and gluing of the veneer sheet, are identical with the method steps for the veneer sheet of the first embodiment.

The method steps for forming of the billets 4 are also identical with the method steps of the method steps in the first embodiment, i.e. pre-pressing the glued veneer sheets to form a billet, trimming the billet and hot pressing the billet. In accordance with the first embodiment, the billet 4 of this second embodiment is also transported to a gluing station. At least one side 5, 6 of the billet 4 is applied with a layer of glue 11. The glue 11 is

preferably applied on the billet 4 by a curtain spreader or similar, where the spreader is stationary and the billet 4 is moving through the spreader.

A predetermined number of glued billets 4 are then placed together to form the building element 14. The first side 5 of the billet 4 is facing against a second side 6 of an adjacent billet 4, such that the billets 4 form the building element 14, which building element 14 comprising a first side and a second side which faces away from the first side. Moreover, at least two adjacent billets 4 are placed mutually offset relative each other in the

longitudinal direction, such that a female/male member is formed at least one of the end portions of the building element 14. Figure 7 discloses a building element

comprising two billets which are mutually offset relative each other in the longitudinal direction, such that a female/male member is formed at the end portions of the building element. Figure 8 discloses a building element comprising three billets 4, which are mutually offset relative each other in the longitudinal direction, such that a female/male member is formed at the end portions of the building element. The building element 14 may, of course, also have a flat end portion 16, which is shown in figure 8.

The building element 14 is then pressed together in a cold pressing step in order to press the glued billets together. The pressing time may be about 25-90 minutes depending on the process parameters such as the thickness of the building element 14, pressure or type of glue. The building element 14 may have a thickness from about 80 mm up to about 400 mm. The building element 14 is then processed in an edge trimming step, where the edges of the building element 14 are trimmed, such that the building element 14 become square formed. The glue line 10, 11 after the pressing steps has a thickness of about 0.1-0.3 mm. If a hot press is used, the glue is normally based on melamine. If only cold presses are used the glue is normally based with polyurethane . However, both glues can be mixed in various ways to optimize the process parameters. The veneer sheets are compressed during the pressing steps. For example, a veneer sheet of 3.5 mm has after the pressing steps a thickness about 3.2 mm.

A final, optional, step is a CNC treatment to form a final shape of the building element 14. The dimensions of the end product can be customized quite flexible to meet customer demands.

The building element 14 of the second embodiment has some major benefits when it comes to transportation of the building element. For example a building element of 2.0 m can be transported in a standard container. After

transportation the building elements 14 are connected together by using glue in the male/female joint between the building elements and by providing necessary pressure to the glue line by using standard screws or an external press. The building elements 14 enables erection of large external walls up to 12 m or larger as shown in figure 3.