DE3308843A1 - Process for producing mouldings from laminate materials - Google Patents

Abstract

The aim of the invention is the production of mouldings having complicated shapes with the aid of simple and cheap pressing technology and with high productivity. According to the invention the laminate material is press-moulded in a first operation in a preferably flat mould and deformed in a second operation utilising the slidability of the layers on account of the viscosity of the adhesive during the deformation to form the moulding. The mouldings can be used in furniture construction, interior fittings, automotive manufacture and in the packaging, toy and sports equipment industries.

Description

Title of the invention

Process for the production of molded parts from sheet materials of the invention The invention relates to a method for producing molded parts made of layered materials such as plywood, layered wood particle materials, Composite materials and paper laminates, their use in furniture construction, interior design, Vehicle construction as well as in the packaging, toy and sports equipment industries is possible.

Characteristics of the known technical solutions It is known Manufacture molded parts from glued layers, such as veneers and / or wood-based panels, by dividing these layers into at least two parts in one of the intended shapes Press tool are pressed together. Such a pressing tool consists in the Usually made of metal and is equipped with a heater for thermosetting adhesives to be able to use.

This is how veneer bundles (1 to 2 mm beech veneer up to a maximum of 38 Layers placed in a steel mold and then using a break of 100 t pressed. The heating takes place with superheated steam. Depending on the thickness of the laminate the pressing time including the post-curing time 10 to 45 minutes.

This method has the disadvantage that high pressures are used must that the pressing tool of the shape of the molded part is very voluminous and is expensive to manufacture, too, to be economical in the manufacture of fermels to ensure that a large number of identical parts must be produced, which can only be varied by subsequent different cuts.

Another method has the production of molded parts for Chairs to the subject. There will be 13 to 19 pieces of veneer using binder solution in a press mold made of plywood and lined with 4 mm thick aluminum sheet Using a hydraulic press at a pressure of 20 kp / cm2 for 470 seconds pressed and heated by means of a high frequency of 13.8 NHz. Then the pressure of 20 kp / cm is maintained for about 110 seconds for the binder to cure.

The disadvantage here is again the use of a compression molding press as well an expensive high frequency generator.

Furthermore, a method is known by the laminated blanks for Arched windows are produced. In a special frame press, exchangeable Stencils glued, about 2.5 mm thick veneer strips pressed into molded parts. Disadvantageous is with this method that a special frame press is required and that the blanks must remain clamped in gauges for 4 weeks so that they do not become forgiven.

Furthermore, the postforming process - a process for coating rounded panel edges with flat laminate panels - known. Also forWr In addition to the press system, this process involves complex special machines such as 3.

Double end profiler, edge banding machine, forming machine, required.

Method of making undercut or otherwise complicated Shaped moldings require pressing tools with displaceable in different directions Printing elements provided segments. Here it comes through the Seams of the segments easily lead to steps and irregularities in the molded part In addition, these pressing tools require high construction costs.

All of these methods have the disadvantage that the die tolerances of the layers to be pressed may only be small, otherwise impermissible geometric Deviations of the molded part, especially in the area of curvatures, arise. the The only risk of incorrect bonding is through excessively high compression of the layers be compensated.

Furthermore, it is disadvantageous in all of these processes that the heating through the glued layers for the purpose of solidifying or curing in the adhesive Press tool takes place.

This becomes dependent on the thickness of the molded part Period blocks and is therefore not very productive.

In addition, all the methods described so far require post-processing The pressed molded parts are expensive due to the more or less complicated shape and difficult to mechanize.

The "postforming" process described also has the disadvantage that the bending radius depends on the thickness of the layer material, so that with the usual Radii on table edges and the like only thin, not self-supporting and mechanical Molded parts or surface materials that can only be stressed to a limited extent can be produced.

For the production of molded parts from flat sheet materials such as plywood, However, processes are also known from other materials in which the layer material is cut several times in the area of the intended curvatures to thereby make it to make elastic bendable. The resulting curvature must be glued the incisions or by subsequently gluing on additional layers. The disadvantages of this process are the low strength of such molded parts in the area of curvature due to the extensive destruction of the material structure through the cuts and in the low productivity, goal of Invention The aim of the invention is a method that is highly productive and the production of different molded parts from low manufacturing costs Layer materials permitted.

Statement of the essence of the invention The object of the invention is to provide a To propose a method for the production of molded parts from sheet materials, the any deformation angles, undercuts, crossings and twists with a high strength and any desired thickness of the molded part. Furthermore, the process should short dwell times of the molded parts in the tool, ie high productivity, low energy costs and large thickness tolerances of the too Allow gluing layers. The mechanical processing of the molded parts should be efficient and be automation-friendly. For the procedure should also be more large molded parts that are easy and inexpensive to manufacture, low-wear ones Pressing tools can be used.

According to the invention, this object is achieved by the layers of a layer material or several layer materials with intermediate layers of an adhesive or several Adhesives are completely or partially layered. Then the layers pressed. This pressing can also be coupled with heating obtained laminated body is then by moving the layers against each other without Opening the glue joints by applying bending and / or torsional forces to one Molded part. This molded part is used until the adhesive layers harden or solidify Preferably fixed in the molded state, the pressing takes place in a planar manner Shape. As an adhesive, customer-specific, reversibly solidifying or irreversibly hardening Adhesives are used. Thermoplastic films have done very well - preferably Polyethylene film at least 0.1 mm thick - proven.

But also with thermoplastic powder and thermoplastic granulate - especially with poly aorylate with a grain size of 1 mm - good results have been obtained.

The hot melt adhesives known in the furniture industry can also do this be used to glue the layers of the layer material, it is secondary, whether the hot melt adhesive in granulate or film form or in the already melted State is used.

Urea resin was optionally used as the irreversibly hardening adhesive or an adhesive dispersion, preferably polyvinyl acetate, is used.

The use of Reversible setting adhesives favorable- Daduroh can be used once or several times repeated plasticization of the adhesive intermediate layers with subsequent complete or partial deformation and solidification take place.

After the method, the deformation of the layer body can be localized or over the whole area.

Between the manufacture of the laminate and its deformation can be used for hardened, partially hardened or

solidified, partially solidified or still plastic adhesive interlayers mechanical processing and / or surface finishing can be carried out.

The heat supply to the layers of the layer material is optional to the layers, to the isolated layers, to the loosely layered or to the Layers that lie firmly on top of one another and are coated with adhesive.

For the production of molded parts, especially those that are planar and have curved areas, it is advantageous to use the postformable layer material only to be used in certain areas, such as the component curvature, while in the remaining areas, preferably in the flat areas, for comparison cheap, non-formable materials, such as Paser or chipboard, for use come.' Cohesion is achieved through partially and / or fully continuous layers of the molded part guaranteed.

Working examples Example 1: 10 layers of 1.2 mm thick veneer are layered with adhesive polyethylene foils 0.2 mm thick and in a flat press at a temperature of 180 ° C and a pressure of 1.2 MPa hot-pressed.

After all layers have been warmed through and the polyethylene foils have melted are, the resulting laminated wood panel is removed from the press. That still viscous glue prevents the glue joints between the veneer layers from opening and allows manipulation and cutting or milling of the still hot ones Laminated wood panel into strip-shaped parts. After fast onward transport or Intermediate storage in thermally insulating or heated mmers is such a strip bent by hand around a gauge corresponding to the shape of the desired molded part or laid around, with expediently at the beginning and at the end of a circumference, when changing the direction of curvature or at the beginning and at the end of a twist Holding block or a holding fork is arranged. To accelerate the solidification of the Adhesive can blow the entire device, which is made of sheet metal, with air will.

In this way, rounded parts for chair frames are made manufactured.

Example 2: According to a second embodiment, there are 18 layers of the veneer, coming from a veneer dryer at a temperature of 180 ° C, sprinkled with powdery polyacrylate with a grain size of t mm, layered and briefly with a pressure between a pair of rollers without additional heat supply compressed by 1.8 MPa, whereby the layer material formation is already completed is. The layered material plate is placed in a bending device that consists of the later molding consists of moldings enclosing both sides or several segments and with the help of gravity it is closed, thus causing the deformation necessary Bending forces as well as those up to the solidification of the adhesive required holding forces applied mechanically. The device is made of wood. The format processing, such as Bosch cutting of the edges and milling, takes place on the curved Molded part.

This. Molded parts are used, for example, as chair frames.

Example 3: According to a further exemplary embodiment, instead of the thermoplastic polyethylene or pelyacrylate used in the furniture industry known hot melt adhesive used, the means of beo known roller application machines is rolled out on 4 layers of veneer at a temperature of 180 e. During onward transport the veneer layers, the heat dissipation of the hot melt adhesive is due to the action prevented by radiant heaters.

The veneer layers are layered with nooh liquid wood glue and briefly pressed together in a cold flat press. Through heat compensation between the veneer layers and the adhesive as well as through the release of heat from the pressed The hot-melt adhesive solidifies the solid wood panel, which causes the panel formed in this way Can be stored as required and is sawn, milled or drilled according to customary methods can be. For deformation, the processed plate is brought to one temperature as a whole of 130 ° d, including a hot plate, a radiator field, one operated with hot air Heat duct or a heated flat press can be used. After heating the bending of the laminated wood panel is carried out in the manner described.

These molded parts are used as handle elements on furniture.

Example 4: A further variant of the adhesive is hot-curing urea resin used, by adding the appropriate hardener at a temperature of 100 * in condensed for a few minutes. 6 fibreboard with a thickness of 1.6 mm each brought to a temperature of 120 ° C, in a roller application machine with urine resin provided and immediately layered to form a layer material, whereby paper laminates are applied as outer layers. Immediately after shifting the pressing takes place in a pair of rollers and then the bending of the sheet material in the manner described. The bending must be completed before the Urea resin has reached the final solid state o The bending device must prevent the heat dissipation of the part in order to ensure complete and rapid curing of the resin, e.g. by lining the contact surfaces with heat-insulating Material such as felt The molded parts are used as curved seat and backrest surfaces Use.

Example 5t According to a further exemplary embodiment, an adhesive dispersion - polyvinyl acetate - used. This adhesive is applied to 3 mm thick chipboard poured in the cold state using casting machines. Then the layering takes place the 4 chipboard and the pressing together between a pair of rollers with a low Pressure, which only creates complete contact with the liquid adhesive surface must be achieved with the adjacent chipboard. The layer material thus formed is now bent with a radius of 300 mm and in this position in the specified manner and Way fixed until the adhesive by releasing its moisture to the chipboard and is firm to the environment.

The molded parts are used for round table frames.

Example 6: According to another example, it is possible to use inexpensive, irreversibly hardening adhesives with reversible adhesives, such as the above hot melt adhesive to combine. If a molding consists of a larger flat surface and a curved edge, so the veneer layers in the area of the later flat surface of the molded part with urea resin and the remaining areas with hot melt adhesive will. When hot pressing the layers in flat presses, they are made with urea resin coated Areas firmly and irreversibly glued while the edge areas either immediately after removal from the press or after a later reheating can be bent and fixed in the manner described.

This method is suitable for furniture floors with shaped curves.

The method shown in Example 1 is advantageous efficient layer material production in productive flat presses, which lends to Automated mechanical processing of the strips in flat form, the simple one Structure of the bending device, the short dwell time of the molded part in the bending device and, in particular, the possibility of using molded, undercut, intersecting, if twisted in all three directions, molded parts without special ones To manufacture meth expenditure. For example, it is possible to have a chair or armchair frame from a few, in extreme cases from a single component.

Compared to the first application example, example 2 shows a low energy consumption by using the drying energy and the possibility the mechanization of the verification process.

Advantageous compared to Examples 1 and 2 in Example 3 is the higher bond strength, which is achieved through the more expensive hot melt adhesive will. Any temporal separation of manufacture of a laminated wood panel from When they are deformed into a molded part, a central plywood production facility, shipping of semi-finished products and processing in user companies is possible.

The advantage of using an irreversibly hardening adhesive in example 4 the very favorable price is with good adhesive strength.

In Example 5, it is advantageous that the adhesive is heated or the layers to be bonded are omitted and thus energy is saved.

The advantage of the solution shown in example 6 is the possibility of Process molded parts in stages. In the extreme case, between the individual There are large temporal differences in processing stages and the production facilities could be territorially separated for the individual processing stages.

Example 7: Three layers of a known, post-formable, thermoplastic bonded wood fiber material with a thickness of 4 mm each are together with 0.2 mm thick polyethylene foils layered.

The outer layers are sandwiched with the same polyethylene film each with a 0.8 mm thick beech veneer layer or a paper laminate layer covered. This layer package is made at a temperature of 180 ° C in a flat press pressed and then in a bending device according to the embodiment 2 bent to a quarter-circle shaped part with an inner radius of 30 mm. This molded part is used as a component transition on a container furniture.

In contrast to a post-formable, thermoplastically bonded fiber board, the thickness of which is equal to the thickness of the five-layer molded part described A much smaller radius of curvature is achieved here without cracking in the material. The risk of cracking is also due to the external, more rigid and more rigid veneer or paper laminate contained.

Example 8: According to another example, every two Crossing veneer layers with a thickness of 0 to 8 mm as cover layers of a layered material non-malleable, conventional chipboard from 14 mm thickness for the later flat areas and 8 layers of 1.8 mm thick veneer used for the later curved areas. All layers are 0.2 mm thicker Layered polyethylene film. The pressing and bending are carried out in the same way as the example 2, wherein the molded part is box-shaped or frame-shaped. The 4 bending edges, in whose area the veneer layers are arranged as a middle layer, have an inner radius of 10 mm. The molded part is used as a furniture body.

As a variant, a wood fiber board can be used instead of the wood chipboard medium density and instead of the 8 veneer layers in the curvature area one or more Layers of post-formable, thermoplastically bonded fiberboard can be used. Through this will be on the later processed cut surface of the molded part over the circumference uniform appearance is achieved, so that a subsequent coating of the cut surface with solid coating materials can be omitted if necessary.

When using non-malleable, flat middle layers, it is advantageous such as chipboard or fiberboard iQr the later flat areas of the molded part of the im Low material costs compared to the malleable materials.

Example 9: A layer of known postformable, thermoplastically bonded Wood-based material with a thickness of 3 mm is covered on both sides with 0.7 mm thick beech veneer and pressed at a temperature of 160 ° C in a flat press. The thermoplastic The binding agent of the wood-based material is dimensioned so that the intermediate layer, for example a polyethylene film acting as an adhesive is unnecessary. After hot pressing it will the flat plate cooled so far in a pressing device with flat pressing plates that plastic deformation is no longer possible. Then if necessary

in another production facility and after longer additional storage, the panel is processed by sawing, milling, drilling and grinding. then the processed plate is brought to a temperature of 160 ° C and in the already described type curved. The binding agent of the thermoplastically bound wood-based material at the joint between the veneer and wood material enables the inventive Shift of the layers. The resulting molded part is used as part of a storage unit door, possibly used in combination with a support structure.

Claims (17)

Invention claims 1. Process for the production of molded parts Layer materials, characterized in that the layers of a layer material or several layer materials with intermediate layers of an adhesive or several adhesives wholly or partially layered, pressed or heated and pressed that the laminated body obtained in this way by shifting the layers against one another without opening the glue joints duroh application of bending and / or torsional forces to a molded part is molded and that the molded part until ZW "hardening or solidification of the adhesive intermediate layers is fixed in the molded state. 2o method according to item 1, characterized in that the pressing takes place in a flat porm. 3G method according to item 1, characterized in that as an intermediate adhesive layer a reversible and / or an irreversibly solidifying or hardening adhesive is used. 4. The method according to items 1 and 3, characterized in that as reversible solidifying adhesive thermoplastic films, preferably polyethylene film of at least 0.1 mm thickness is used. 5. The method according to items 1 and 3, characterized in that as reversible solidifying adhesive thermoplastic powder or granulate, preferably polyacrylate with a grain size of 1 mm is used. 6. The method according to items 1 and 3, characterized in that as reversible a hot melt adhesive is used to set the adhesive. 7. The method according to item 1, 3 and 6, characterized in that a Hot melt adhesive is used in granulate or film form. 8 ¢ method according to items 1 and 3, characterized in that as irreversible hardening adhesive a urea resin is used. 9. The method according to items 1 and 3, characterized in that as irreversible curing adhesive an adhesive dispersion, preferably polyvinyl acetate, is used will. 1 method according to items 1 and 3 to 6, characterized in that after the adhesive has set, a single or multiple repeated complete or partial plasticization of the adhesive intermediate layers and subsequent complete or partial deformation and solidification occurs. 11. The method according to items 1 and 2, characterized in that the Deformation of the laminate takes place locally or over the entire area. 12. The method according to items 1 to 10, characterized in that between the production of the laminate and its deformation when cured, partially cured resp. solidified, partially solidified or still plastic adhesive interlayers mechanical processing and / or surface treatment takes place. 13. The method according to item 1, characterized in that the warming clock to the isolated, to the loosely layered or to the adhesive layered, Layers lying firmly on top of one another are carried out. 14. The method according to items 1 to 13, characterized in that at Molded parts, especially those that have flat and curved areas, the post-formable layer material is only partially used for the trimmed areas is made, while the remaining areas, especially the flat areas non-postformable layer materials are built up, partially in each molded part and / or continuous layers are included over the whole area. 15. The method according to item 1 to 14, characterized in that the The layers to be bonded consist of elastically malleable types of material. 16. The method according to items 1 to 15, characterized in that as elastically formable materials veneers, cardboard, papers and / or thin wood particle boards can be used. 17. The method according to items 1 to 16, characterized in that as plastically malleable materials corresponding wood fiber boards or chipboard are used will.