DE3518483A1 - GLUE-BASED Plywood BEAM AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Description

BASF Aktiengesellschaft "" O.Z. 0050/37730

'S *

Glued glued laminated timber beam and process for its manufacture

The invention relates to a glued glued laminated timber beam with external Deck boards made of solid wood.

Glulam beams are usually made of straight glued laminated timber several boards, mostly softwood, a thickness of 22 to 32 mm and a width of 130 to 200 mm are glued together. The height of the carrier is determined by the number of layers. The strength of the carrier will be tO very often due to the frequency with which branches or knotholes appear and negatively affects their size. In addition, boards made of solid wood are relatively expensive.

The invention is based on the object of a glued laminated timber beam with external deck boards made of solid wood, as well as a process for its production to be provided, the strength of which does not Fluctuations due to irregularities in the glued individual components subject.

This task is solved with a glued laminated timber beam of the mentioned type, which is characterized in that in the middle layers instead of solid wooden boards, strips of chipboard glued together of high strength quality are arranged.

According to a preferred embodiment, the chipboard strips are related the deck boards made of solid wood upright.

The process for producing the glued laminated timber beams of the The above type is characterized in that chipboard strips are glued flat on top of one another in the cold process or with high-frequency heating, the Block of glued chipboard strips trimmed in parallel and glued between outer cover sheets made of solid wood.

In the glulam beams according to the invention, the boards in the Part or all of the center of the support has to be replaced. As chipboard strips or sections, high-strength qualities are used. For example, you can use high-strength chipboard of quality V 100 - E1, which have the following characteristics:

Density kg / m ³ 800 - 850

Flexural strength N / mm ² 30.0 - 35.0

Transverse tensile strength N / mm ^{2 1.20-1.50}

Swelling after 24 h in 7. 3.0 - 5.0

BASF Aktiengesellschaft -Z * - OZ 0050/37730

■. 3.

In addition, so-called OSB chipboard can also be used in certain cases directed long chips are used. These plates have the following Characteristics:

Density kg / m ³ 670 - 700

Flexural strength N / mm ² 40.0 - 45.0

Transverse tensile strength N / mm ^{2 0.60-0.80}

Swelling after 24 h in I 8.0-10.0

IQ The advantage of higher flexural strength is opposed to the disadvantage of higher swelling and the significantly higher price of OSB panels, so that this panel quality can only be used for special purposes.

For the production of the glued laminated timber girders according to the invention The chipboard used can be produced as follows:

The chips of the top and middle layer of the chipboard consist, for example, of two thirds of oak and one third of softwood, preferably spruce or fir. The chip thickness is between 0.3 and 0.6 mm. The proportion of fine dust in the middle class should be below 10 7. A melamine-urea-phenol-formaldehyde resin, as described, for example, in DE-C-20 20 481 or DE-C-29 51 957, is preferably used as the glue. The solid resin dosage, based on absolutely dry chips, should be 13.0 to 15.0% by weight for the top layer and 11.0 to 13.0% by weight for the middle layer. The solid wax dosage, based on absolute dry chips, the top layer should be 0.8 to 1.0 wt. Z ₁ for the middle layer 0.6 to 0.8 wt. 7. The hardener used is preferably a dicarboxylic acid mixture (for example hardener of type 15 in flake form from BASF Aktiengesellschaft) or a formaldehyde-binding hardener according to DE-A-34 00 669. In the poured chip cake, the chips should have a moisture content of about 9 to 11 percent by weight in the middle layer and 12 to 15 percent by weight in the top layer. the hydraulic press should have a specific pressure of 3.0 to 4.0 N / mm ² enabling, so that the press can be driven in spite of the high density of plates within 10 to 15 I of the total press on spacer strips. Under these conditions can be referred to Chipboard produce that correspond to the characteristics mentioned at the beginning and, as high-strength chipboard, form a prerequisite for the glued laminated timber beams according to the invention.

For the production of a glued laminated timber beam according to the invention, which for example has a cross-section of 50 χ 15.4 cm, one goes e.g.

BASF Aktiengesellschaft - / - O.Z. 0050/37730

Proceed as follows: There are chipboard of the high-strength described Quality with a thickness of 22 mm cut into strips 38 cm wide. There will be seven pieces of these chipboard strips of any length with an approved wood glue construction, preferably a melamine-urea-phenol-formaldehyde resin according to DE-A-20 43 440 glued flat on top of each other in the cold process or with high-frequency heating. The block out The glued panels are trimmed parallel to a width of 36.8 cm. If a precision saw is not available, calibration with a wide belt sander is recommended. Then the block is upright tO standing between 3 spruce boards each 22 mm thick with the aforementioned Gluing glued. In this way, a 50 cm beam is obtained Height, which is much cheaper to manufacture by replacing 16 to 17 board layers of 22 mm with the high-strength chipboard.

The invention is illustrated below by way of an example and the like Explain comparative data in more detail.

example
The following experiments were carried out on a laboratory scale:

A carrier made of 5 layers of knot-free spruce boards 22 mm thick was used in the cold process with Kauramin® glue 545 liquid (according to DE-A-20 43 440) glued. The dimensions of the carrier after planing were 550x107x64 mm.

According to the invention, four carriers of the same dimensions were produced in each case which only the two outer layers consisted of spruce boards, the middle three layers, however, from the aforementioned high-strength chipboard were educated. In one case the three glued panels were upright arranged standing. In the other case, the three high-strength chipboards were laid flat. The thickness of the chipboard was in each case 22 mm. The gluing conditions were identical to those of the carrier made of 5 layers of solid spruce boards. A comparison of the physical Properties of the laminated timber beams thus produced resulted in the following Results:

BASF Aktiengesellschaft

strength

. s.

Carrier off

5 layers of spruce

22 mm thick

O.Z. 0050/37730

Carrier made of carrier made of 2 outer layers of spruce, 2 outer layers of spruce and 3 lying flat and 3 edging on edge Chipboard glued chipboard 22 mm thick

of 22 mm

Mean a. Pc. 1 F max (N) 32640 0 * 8 (N / mm ² ) 33.4 10 Ε module (N / mm ² ) 1775

29918
30.6
1770

40788 41.8 2129

The middle 3 spruce boards were made by laying flat chipboard replaced, there was a slight decrease in strength compared to the pure spruce wood carrier. In contrast, the porters with the upright ste-75 existing chipboard has significantly higher strengths.

Claims (4)

BASF Aktiengesellschaft O.Z. 0050/37730 Claims . Glued laminated timber beams with external deck boards made of solid wood, marked by the fact that in the middle layers instead of solid wood boards, glued together chipboard strips of high-strength quality are arranged. 2. Glued glued laminated timber beam according to claim 1, characterized in that the chipboard strips are upright with respect to the cover boards made of solid wood. 3. Glued bed plywood support according to claim 1 or 2, characterized in that; that the chipboard strips have directed long chips. 4. A method for producing the glued laminated timber beam according to one of claims 1 to 2, characterized in that chipboard strips are glued flat on top of one another in the cold process or with high-frequency heating, the block of glued chipboard strips is trimmed in parallel and glued between outer cover boards made of solid wood. 220/85 Hoe / ro 22.05
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