FI74239B - FOERFARANDE FOER FRAMSTAELLNING AV CROEKTA LAMINATYTOR GENOM LIMNING. - Google Patents

Description

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Method for preparing curved larinate surfaces by gluing

The invention relates to a method for gluing curved laminate surfaces in a new way. By curved laminate surfaces is meant here the sheets originally glued in layers from straight sheets to a new curved shape. Such are, for example, the seat plates of chairs shaped according to the body, glued from wood veneers.

The prior art and most commonly used method of making glued curved laminate surfaces is to press and glue the sheets in shape between two rigid mold halves, using the force most commonly provided by hydraulic cylinders as the pressing force. A spacer made of some resilient material, most commonly rubber, is used between the mold halves to remove the effect of minor mold defects and to equalize the gluing pressure.

Prior art gluing methods have several drawbacks, the most detrimental of which is that they do not make it possible to produce curved laminate surfaces in which a part of the surface is parallel to the direction of compression.

Other disadvantages are that when gluing with the old methods, only the average gluing pressure is known. The actual distribution of the pressure 20 on the surface to be glued is unknown and it is generally the case that the surfaces perpendicular to the compressive force receive a higher pressure than the parts of the surface oblique to the compressive force. This adversely affects the quality of the product and places additional strain on the support structure of the tool system. Namely, the gluing force 25 must be chosen according to the part of the surface which receives the lowest pressure.

Further disadvantages are the difficult control of the gluing pressure, as the pressure distribution is not known, the difficult conductivity of heat to the body to be glued through the resilient spacer in applications where heat is required in the gluing process and the pointic forces required to achieve the desired gluing pressure This raises the cost of the tool system, especially in terms of hydraulics.

By means of the invention referred to in this application, all the above-mentioned disadvantages of the methods currently in use can be eliminated by using a new, simple technique.

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It is characteristic of the present invention that the gluing method has two clearly distinguishable steps, for each of which the mold solution applying the method has separate components. The bending of the sheets to be glued close to the correct shape and the actual gluing 5 together are performed separately using different components and preferably also with a different power source.

The main advantage achieved by the invention is that the new method can also be used to produce laminate surfaces in which some part or parts of the surface can be parallel to the direction of compression.

10 Furthermore, the cost of the tools required in the gluing process will be lower than that of the tools currently in use due to the fact that expensive high-pressure hydraulics are not required. In addition, the automation of the gluing procedure required for series production is easy when delivered with the new method, because the same liquid can be used for both pressurization and heating. Controlling the pressure and temperature of a liquid in automation is known to be simple.

The new method makes it possible to use a uniform, precisely controlled gluing pressure and temperature, which has an undeniably beneficial effect on the uniform quality of the products.

The main features of the invention are set out in claim 1.

In the accompanying drawings, the method referred to in this application is illustrated by a mold solution applying the method. In addition, the 25 most commonly used "old" methods are also presented in order to find out the essential differences.

Figure 1 shows a cross-section of the most common mold system in use, where point-like forces F are used to press the straight, glue-treated sheets 2 into molded products 2 using the mold halves 3 and 5. The resilient spacer 4 acts as a pressure equalizer. When supplied with this method, the "emission angle" A of product 1 cannot be less than 4-5 degrees. The smaller the discharge angle A, the worse the sides "pressurize".

Figure 2 shows a cross-section of a tool application of the new method required by this patent application and in particular the first step of the gluing-35 procedure.

Figure 3 shows a cross-section of the same type of mold when the bending step is completed.

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Figure 4 further shows a cross-section of the same mold when the gluing pressure is "switched on".

Figure 5 shows a type of rack required in the gluing procedure and the situation in which the straight boards to be glued are placed in place.

5 Figure 6 shows the same rack when the bending step has been completed and the gluing pressure can or has already been "switched on".

The following illustrates, with the aid of Figures 2 to 6, the operating principle of the gluing method referred to in this application and the general structure of a tool system applying it.

The adhesive-treated straight plates 8 are placed on a liquid-filled solid mold half 13 in the gluing position to produce the product 6. The structure of the fixed mold half includes a perforated plate 12, an adhesive film 11, seals 10 and a seal tightening strip 9. The hole diameter D of the perforated plate 12 does not necessarily have to be the same along the width of the perforated plate 15, but by varying its size. Both mold halves are filled with liquid. The fluid of the upper movable mold half is used to heat the mold and the fluid of the lower fixed mold half is used both to heat and to provide the gluing pressure. The mold halves 7 and 13 can best be made of steel as well as a perforated plate 12. The film 11 can be, for example, a thin brass plate or some other suitable metal film, provided that the width of the film between the sealing paths 10 is the same in steps 3 and 4. This is achieved by selecting the correct shape 25 for the perforated plate 12 relative to the mold half 7. If it is desired to use a stretchable film material, not much dimensional accuracy is required of the above-mentioned shapes.

The first step of the method, bending of the plates, in this case is carried out by pressing the upper mold half 7 against the lower mold half 13 by means of a hinge mechanism 15 driven by a threaded rod 16, for example, so that the desired mold position is achieved and the levers of the mechanism 15 "lock" as shown. The force G required in this bending step is only a fraction of the force H caused by the gluing pressure. In the mold performance tests performed, a ratio of about 1/20 was measured for the forces G and H. In the experiments, a triple wood veneer laminate was glued to a curved shape. The thickness of the finished laminate was 3 mm.

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The small size of the force G compared to the force H makes it possible to use a simple and inexpensive mechanism to perform this bending step.

The second step of the method, gluing the plates 8 together, is carried out in this exemplary case by pressurizing the liquid inside the fixed mold half 13 5 to the required gluing pressure P1, for example using a low-pressure hydraulic pump. If heat is required for gluing, the pressurizing fluid can be heated to the desired temperature, for example using electric resistors. In this exemplary case, the additional force H caused by the gluing pressure P1 is received by the articulation mechanism 15 and the frame-14 structure 14.

The two-step gluing method described above can be used for a wide variety of purposes, especially when the part to be manufactured has surface portions parallel to the compressive force H. Among the uses, e.g. manufacture of plywood surfaces for various curves, curved pieces to be glued from 15 different plastic-based boards and curved plastic-wood laminate combinations.

Claims (4)

5,74239 A method of manufacturing curved laminate surfaces (6) by gluing, characterized in that the gluing takes place in two distinct steps: the first step, pre-bending of the straight sheets (8) to be glued, is performed by pressing the sheets with a movable mold half (7) as part of a fixed mold half (13) against the sheet (12), and the second step, the actual gluing, is performed by pressurizing the liquid or gas contained in the fixed mold half (13) with the desired gluing pressure, causing the thin, edge-sealed gluing film (11) on the perforated sheet (12) to press against the sheets to be glued. when the plates (8) are pressed against the movable mold half (7) shaped according to the part to be manufactured. A method according to claim 1, characterized in that the fixed mold half (13) is shaped according to the part to be manufactured, wherein the perforated plate (12) and the pressure film (11) are part of the movable mold half. Tool system according to one of Claims 1 or 2, characterized in that one of the mold halves (7 or 13) comprises as components a perforated plate (12) which receives the bending of the plates and a thin film (11) required to provide a gluing pressure. Tool system using the method according to claims 1 or 2, characterized in that the structural principle according to claim 3 is applied in a part of the molds.