DE2606924B2 - Process for the production of plate-shaped structural elements that can withstand shear loads - Google Patents

Description

The invention relates to a method according to the preamble of claim 1.

Such a method is known from GB-PS 13 81 637 and DE-PS 9 49 524. In the process According to DE-PS, a fiberboard or the like is used as a cover plate by combining with one another connected stiffeners as latticework secured against kinking and bulging. The attachment of the The latticework on the plate is flat-shaped by means of gluing. The stiffeners can open be covered with panels on both sides. How is glued in detail, is the Print not removable.

In the process known from GB-PS, large disks of the type that are also used after the process are to be produced according to the invention, in a device receiving the plates using a hardening adhesive and applying pressure. A stack of components in a chamber is enclosed, and the chamber is placed under negative pressure, with a correspondingly movable formation of at least one wall of the chamber, the pressure difference between the negative pressure in the chamber and the atmospheric pressure the pressure required for a perfect bond The pressing devices are expensive and there is a relatively long residence time in the Chamber necessary.

Known cover plates made of chipboard or the like usually have a flexural modulus of elasticity of about 100,000 kg / cm ² and below. The term "flexural modulus of elasticity" used here denotes a value for the section modulus of the material that depends on the material properties and dimensions

H) Cross-section in relation to the zero line for the tension and compression side. So the plates bend that way The easier it is, the lower the flexural modulus of elasticity. The invention is based on the object 2grund

The method of the type described in the preamble of claim 1 to be designed so that for the Bonding of the latticework with the cover plate or the cover plates of a component is no special Means for applying the pressure or for clamping are required.

This object is achieved according to the invention by what is contained in the characterizing part of claim 1 Features solved.

Thereafter, an adhesive is used which hardens essentially in a completely dimensionally stable manner, i. E. H. the shows no shrinkage when hardening, and on the other hand, the adhesive is applied in an amount which is sufficient to exercise in any case, including ohiie an additional pressure, all differences in the Height of the by loosely laying on the cover plate

) (i to the gap forming the edge surfaces of the latticework compensate. When the cover plate is put on, the adhesive is displaced by its own weight to such an extent that that a complete gap filling is achieved, this gap filling due to the lack of shrinkage

r> of the adhesive even after hardening. This makes it possible to use the adhesive surfaces on the cover plates and on the edge surfaces of the bars forming the bars, to be left practically in the delivery condition, d. H. not to be processed or only to a small extent.

The adhesive can be applied to the adhesive surfaces as a strand or in the form of drops, and as a result Relatively large adhesive gap height due to the pressure exerted only by the weight of the cover plate even distributed over the entire adhesive surface. There are also no special devices to apply pressure exercise and maintain this contact pressure until the adhesive hardens. Under “Pressureless” is only to be understood as the pressure created by the dead weight of the cover plates.

In the method according to the invention, the accuracy in cutting the parts is not critical, and it is easy to apply the adhesive and monitor the joining of the elements. It there are essentially no connecting surfaces with a larger gap than the one required Strength can be bridged by the gap filling adhesive.

The components produced by this process have the same physical properties as

bo components manufactured according to previously known methods are made such. B. by nailing (DE-PS 9 49 524) or gluing under pressure (GB-PS 13 81 637) of panel materials with a wooden lattice work.

b5 The two methods used according to the invention Resorcinol or resorcinol / phenol resin based on formaldehyde contain fillers known per se, z. B. coconut shell flour and / or colloidal silica

re. A suitable filler content is 5 to 60% by weight, preferably 10 to 25% by weight, based on the composition. A high solids content is preferred.

Since the adhesive has thixotropic properties, it is easy to handle and stable in itself Shape before and during application. This property is known by adding thixotropic agents such as B. colloidal silica causes. As a preferred area of thixotropic was the following after the Brookfield RVT rotary viscometer, sp. 7, measured area determined:

At 1 rpm 20 0 (K) to 2,000,000 cP, 5 rpm 55,000 to 550,000 cP and 50 rpm 10,000 to 100,000 cps.

The amount of adhesive applied, e.g. B. the dimension of the adhesive strand applied is important for achieving a well-filled adhesive gap. The diameter of a strand should be Exceed 2 mm and are preferably in a range of 3 to 10 mm. If the surface is too rough Adhesive surfaces are preferably laid two strands to ensure good distribution and gap filling to ensure.

If the adhesive is cold-setting, it will harden in a not too long time at a temperature below 35 ° C.

A material is used for the latticework that changes in dimensions approximately uniformly in the X, Y and Z directions with changes in humidity and temperature. Materials with constant dimensions that are suitable for use as latticework in the structural elements are wood-based fiber and composite materials.

The adhesive can be applied manually or automatically, e.g. B. with the help of a gun, are applied in the Adhesive and hardener are mixed automatically in appropriate proportions or with the adhesive and hardener must be applied separately.

The following is a description of exemplary embodiments of the invention with reference to the drawings.

In the drawings shows

F i g. 1 is a plan view of a latticework,

2-9 a method for producing plate-shaped Components.

The latticework according to FIG. 1 consists of a number of parallel webs 1. They are perpendicular to these Cross webs 2.3 are provided at the ends or between them.

To connect the latticework, the webs are held in place, e.g. B. with the help of fittings, Internal connections, stop pieces nailed to a support or point stapling.

The spaces between the latticework can be covered with insulation in the form of glass or mineral fiber panels, or directly with plastic foam be filled. Any reinforcement that may be required can also be provided in these spaces be.

A preferred procedure will now be described with reference to FIGS. 2 to 9 explained.

After creating the latticework 11 is on a laid down flat support 14, glue on the edge surfaces of the webs with the aid of a gun 15 (Fig.2) applied, and a cover plate 12 placed on it (Fig.3). This process is done by putting on repeated by further elements until a stack 17 (Fig. 4) is created. An additional plate is made if necessary placed on top of the last element to improve the contact. When the glue in the gaps has solidified sufficiently, the elements are turned 180 ° (Fig. 5) rotated Then insulating material 16 is installed if necessary (Fig. 6). Then glue is applied to each Edge surfaces of the webs applied to the other sides of the latticework (Fig. 7), and one more each ι »Cover plate 13 placed (Fig.8). up a batch of completed elements is created (Fig. 9).

example 1

A latticework of chipboard webs was put together by π fixing with one edge in a holder and connected with the help of some brackets or a hot melt glue. In the An insulating material was inserted into the latticework. An adhesive having the following composition was made 2 (1 applied to the edge surfaces of the latticework:

Resorcinol phenolic resin

(Dry content about 70%) 100 parts by weight

Formalin solution (37%) 25 parts by weight

Coconut shell flour 25 parts by weight

A chipboard was placed as a cover plate on the edges covered with adhesive and with the help some brackets secured against shifting. This construction was turned over and strands of glue

in were on opposite edges of the Lattice work was applied and then another chipboard was placed on top. A number of elements were placed on top of each other and stored for about 3 hours. Then the glued edges

The r> ten surfaces have a shear strength of at least 15 kp / cin ² .

Example 2

A latticework of webs made of 19 mm thick ■ plywood or chipboard are held together and attached to a surface of a 10 mm thick chipboard that rests on a flat surface. the The upper edge surfaces of the webs are provided with an adhesive layer that is applied when the ■ r> cover plate at least 0.5 mm thick of a thermosetting Resorcinol-based resin, which has the property that it completely fills the gap after a chipboard has been placed as a cover plate on the upper side of the frame.

w The adhesive is used to harden only the compressive force exposed to the weight of the top chipboard. The adhesive used is as follows Composition:

Resorcinol resin

'' (Dry content approx. 60%) 100 parts by weight

Formalin solution (37%) 25 parts by weight

Coconut shell flour 25 parts by weight

The cover plates were placed on a plate heater

W) was preheated at 140 ° C for 2 minutes before opening the latticework was put in place. The shear strength was determined at various time intervals. Included the following results were obtained:

b5 3 min. after connection

5 minutes after connection

10 minutes after connection

20 minutes after connection

2.5 kgf / cm ²
6 kgf / cm ²
13 kgf / cm ²
23 kD / cm ²

The hardening could accelerate the hardening of the adhesive, so that the elements could be transported or handled quickly.

After less than 5 minutes the strength was sufficient for transportation, and after 10 minutes the strength was that Area as required for the finished construction.

When determining the shear strength, fractures always occurred in the material of the cover plate and not in the Connection between edge or web and adhesive.

Example 3

A number of laboratory tests have been carried out with different combinations of materials in bonding the components, d. H. with different cover plate materials, different lattice materials and carried out at various disruptions. as Various types of plywood, fiberboard, and particle board have been used, and facing materials the same materials and wood were used as the lattice material. The thickness of the materials varied from 10 to 20 mm. A resorcinol-phenol-based adhesive with the following composition was used:

Resorcinol phenolic resin
(Dry content about 50%)
Formalin solution (37%)
Coconut shell flour
pH

loo weight parts
25 parts by weight
21 parts by weight
7.5 to 8.0

In addition to the weight of the plates themselves, no additional pressure was applied. The results are summarized in the table below. These results show that cover plates with a relatively low flexural rigidity, ie with a flexural E-module of not more than 100,000 kp / cm ² , preferably less than 50,000 kp / cm ² , are required in the method according to the invention, if no additional! Pressure force is applied.

The materials used for cover plates and latticework were construction materials according to Swedish standards for load-bearing building materials.

The components were loaded until they broke and it was determined at which point of the connection the edge surface of the web-adhesive layer-cover plate de rupture occurred. In the following table, under dei The “Behavior” column indicates what percentage of the fracture surface was in the material of the cover plate.

Table according to example 3

Cover plates the same Flexural modulus Latticework behavior Usability of the the same Component 10 mm chipboard 32,000 kgf / cm ² 10 mm chipboard 100% breakage excellent the same in the chipboard the same 12 mm cardboard the same the same the same 10 mm plywood the same the same plate the same 20 mm redwood 50-75% breakage partly worse in the chipboard Contact as a result of the Warpage of redwood 12 mm cardboard 20000 kgf / cm ² 10 mm chipboard 100% breakage excellent in the cardboard the same 12 mm cardboard the same the same the same 10 mm plywood the same the same plate the same 20 mm redwood the same sometimes worse Contact 10 mm plywood 100,000 kgf / cm ² 10 mm chipboard 50-75% breakage partly worse plate in the plywood sheet Contact due to delay the plywood sheet 12 mm building board the same the same 10 mm plywood the same the same plate 20 mm redwood the same the same

and of redwood

Example 4

For insulated, load-bearing structural elements with dimensions 8 χ 24 m, which are intended for external walls, a chipboard with dimensions 8 χ 24 m and a thickness of 12 mm was used as the cover board. The latticework consisted of webs 16 cm wide made of the same chipboard material. The lengths were different. The same adhesive was used as in Example 2. Glass fiber wool with a thickness of 16.4 cm was used as the insulating material. The structure corresponds to that of FIG. There;

Latticework was 20 mm within the outer edges of the cover plates, and the distance between the webs of the Lattice work was 50 cm.

A chipboard was placed on a flat, vertically adjustable table, the bendable Chipboard lay tightly on the table. In order to form a latticework as shown in Fig. 1, were short system pieces 4 (Fig. 2) with dimensions 2 χ 2 χ 1.5 cm on the chipboard according to the nailed the creating latticework. The distance between the paired pieces was about 80 cm, and the distance between the pieces in a pair was 12 mm. Before assembling an approximately 5 mm high adhesive strand was applied to the edge surface of the bars and the Cover plate placed. There was no gap at any point of connection between the latticework and the cover plate larger than 1.5 mm can be determined.

After turning the element over, glass fiber wool and a diffusion wall were created in this way built-in box-shaped structure. Strands of the same adhesive were applied to the edge surfaces on the Applied top of the latticework, and then the top cover plate was placed.

The resulting element formed a stack with five other elements. A chipboard of 22 mm with the same dimensions as the cover plates was placed on top of the stack. Despite one just through the dead weight exerted pressure force and despite the large dimensions could connect well in all glue joints of the stack are achieved, and glue joints larger than 1.2 mm have never been found. Of the Stack was cured for 2 to 3 hours. After this time they were absolutely solid, non-creeping, weatherproof Connections available. The result was a stiff and dense plate-shaped component, its length deviation was a maximum of ± 2 mm. The cover plates of the elements were completely undamaged, and after that Installation was no additional work, such as filling, etc., before painting or wallpapering necessary.

Samples were taken from the bonded elements, and the shear strength of the layers in the bonded edge surfaces was ^{measured up to 60 kp / cm 2} on average. The required strength in the connection is a maximum of 15 kp / cm ² . Such a wall element was tested in detail, and after all of the bonded edge surfaces had been broken open, a fracture surface was found, more than 90% of which was in the chipboard material.

IliL-rzii 3 HIaIt drawings

Claims (2)

Patent claims: 1. A process for the production of panel-shaped structural elements that can withstand shear loads, larger than 1.0 χ 2.5 m, from a latticework, on one or both sides of which a chipboard, fiberboard or plywood panel (cover panel) with a flexural modulus of elasticity is glued on below 100,000 kp / cm ² , and the webs of which are made of chipboard, fiberboard or plywood material, in which the adhesive is applied and the latticework and the cover plate (s) are placed on top of one another and glued, characterized in that a known, hardening resorcinol or resorcinol / phenolic resin is used which, by adding a filler, is made thixotropic, essentially retaining its shape and not shrinking much during curing, so that it is at least 0.5 mm thick and in such an amount is applied that between the edge surfaces of the webs and the cover plate occurring glue gaps are filled, and that the gluing of the latticework to the cover plate on e one side is carried out so that the application of the adhesive is carried out from above onto the edge surfaces of the webs, then the cover plate is placed and the adhesive is cured without pressure to the extent that the element can be handled, and that in the case of a cover plate on the second side it is one-sided coated element is turned and the second cover plate is applied in the same way by placing it from above onto the edge surfaces provided with adhesive on the upper side of the webs. 2. The method according to claim 1, characterized in that cover plates with a flexural modulus of elasticity below 50,000 kp / cm ² are used.