DD271670B5 - Three-dimensionally bendable surface element and method for bending deformation of such a surface element - Google Patents

Description

For this 3 pages drawings

The invention relates to a three - dimensionally bendable deformable surface element according to the postforming principle, which in the

Biegeverformten state as wood-based surface coating material or as inherently stiff thin-walled

Construction material is applicable in the furniture, sports equipment, toy and packaging industries as well as a method for Deformation of such a surface element. Distinctive three-dimensionally deformable surface elements are only made of thermoformable materials such as sheet metal, thermoplastic

or known from molded materials.

In contrast, wood or wood-based materials allow a comparatively very limited three-dimensional formability, which

is due to the virtually non-existent fluidity of wood, wood particle materials and paper.

Another disadvantage is the use of n ured grown raw materials, because their properties partly regarded as inhomogeneous For this reason, there have been attempts for decades by a suitable preparation of the starting materials to be processed

or to improve the plastic deformability of a wood-based material by using technological auxiliaries and agents. On closer examination, however, it turns out that with many known solutions only a two-dimensional bending deformation of the flat or strip-shaped semi-finished products can be made possible.

In this case, only a change in the angular position of adjacent zoned of the semifinished product takes place along a bending line. The Bending line runs z. B. strip-like parts iny direction (transverse to the longitudinal direction) of the semifinished product. Also known Solutions where prepared fiber bundles are used which perform a plastic bending parallel to the fiber longitudinal direction

(Course of the bending line in the x-direction) möglich.'Eine mutual displacement of elements of the semifinished product in the

Thickness direction (z-direction) or a simultaneous displacement of a considered point of the semi-finished product In x-, y- and

z-direction in the forming zone are not described.

Rather, solutions are shown in the prior art, the production of three-dimensionally shaped semi-finished or Construction parts by classical bending methods (open or closed V-bending and U-3iegen) to the subject

to have. The term "spatial bending" used here must not be misinterpreted and equated with an actual, three-dimensional forming process such as deep drawing.

Thus, in DE-OS 3516465 a wood material presented by narrow, parallel strips or rods

is characterized. The object of the invention is to produce a molded strip that allows easy deformation by bending or torsion. An axial reorientation of the overall cross section should be possible by means of one or more bends in all directions of the room.

The plastic deformation takes place only transversely to the longitudinal direction of the rod-shaped semi-finished product (bending line in y-direction) or

optionally parallel to the fiber longitudinal direction (x-direction) by one or more bending operations at different

Positions of the semi-finished product. Only changes the angular position of adjacent zones of the material along the Bending edge. In DE-PS 857272 a wood material is described, which consists of olnem fiber bundle. The fiber bundle is replaced by a

elastic wrapping during the bending process Fixed in position and thus prevented from falling apart.

Such a wrapper in the sense of a shrink film is not in the transformation of Pächenhafter, thin-walled semi-finished products

applicable. Due to the external stresses, there would be a collapse or a folding of the externally vorbeanepruchton, flat semi-finished product. In addition, this would be an unwanted deformation of the Umformteiles in the

Surface zone inevitable. / As in DE-OS 3516465, the plastic deformability of the prepared semifinished product is limited to a partial Angle change by bending transversely to the fiber longitudinal axis (bending line in the y direction) or torsion along the fiber axis

(X-direction).

In US-PS 2 395 468 a single-ply, flat semi-finished product is presented, which has a number of recesses and cuts

to prevent a Qewaltbruch during the subsequent forming process in the x and y direction. Similarly, to improve the malleability of wood veneers, it is common practice to cut the veneers at the critical areas. The gaping after the plastic deformation areas are then by inserting wedge-shaped

Veneer pieces closed. If an overlap in the material area to be deformed is to be expected, the size of the Overlapping cut out according to material. However, these measures require either one

above-average precision or lead to relatively inaccurate moldings, the only by a subsequent

Surface coating (such as with a cushioning material) to quality products such as furniture components

can be further processed. Furthermore, with this way of molding production is always a high manual

Associated work. In DD 245780 a device for producing arcuately shaped, thin-walled workpieces is described. there

is a sheet-like wood material by bending parallel to the longitudinal direction (bending line in the x direction) of the multilayer

Material plastically deformed. The desired shape change and thus the degree of deformation is determined by the design

of the bending die.

Starting materials are known planar planar packs, which consist of several, continuous individual layers,

which are glued together. Fin such material would in a three-dimensional deformation after reaching the '

Yield strength randomly burst, as a simultaneous inner reorientation and alignment of the wood material lay in all three Directions of the room is not possible. The process described in DE-PS1022375 serves to produce thin-walled molded parts by repeated bending in

x and y direction.

To improve the Umformvermögens breakthroughs are provided in the sheet-shaped semifinished, the Cut through the entire cross-section of the semifinished product in the z-direction locally completely. Likewise notches are provided in the edge zones, which have an arcuate outlet to one

counteract inevitable tendency to crack in the plastic deformation. By means of this method and the semi-finished products used for this purpose, only limited degrees of deformation in the x and y directions can be realized, since a

Minimum distance between dan rods and breakthroughs must be maintained to ensure safe initiation and transmission

To ensure the stress forces of the structural parts.

Another significant disadvantage is that the surface of the formed semi-finished product by the (technologically necessary) Breakthroughs and cuts are unintentionally changed. In many cases, however, the surface of a three-dimensionally shaped Semi-finished product directly as a construction part use '.indan. In these cases, a complex post-processing would be

(Filling and gluing the joints, spatulas, multiple sanding) necessary to conceal the visible breakthroughs.

If such a post-treated part is then exposed to greater stresses, in particular in the case of flexural stresses,

This can lead to a breaking out of the filling material from the subsequently closed joints. Through this

The disadvantage is the field of application of this method and the workpieces produced thereby severely limited. In the DR 704619 eiVi method is presented, in which a facilitated deformation of solid wooden strips when bending transversely to the Longitudinal direction (8'cgeiinie in y-direction) is made possible. Again, there is a completely different task, since the

Known method is applicable only to local bending deformation massive profile cross-sections.

In addition, solutions are known to the deformability of wood by plasticizing mitteis moisture and heat or

to improve within limits by means of chemical substances (ammonia). The plastic deformation of a wood material, however, requires high mechanical forces that lead to stability problems (wrinkling, wrinkling, breaking) and tensile stresses when applied to thin surface elements such as veneers, which can cause the fracture of a respective element very quickly transversely to the fiber direction.

Also known are multilayer plate-shaped wood particle materials, the full surface with thermoplastic binders

are provided to improve the fluidity. As a result, the bending ability in the x or y direction is substantially increased, but a three-dimensional transformation is not possible due to similar manufacturing and technological problems as in the transformation of wood.

in DD-WP 219724 a method for pronounced three-dimensional deformation of surface elements of virtually non-flowable and not tiefziehfähiyen materials is given, in which a folding mechanism is formed with non-linear fold edges. However, the achievable shapes are severely limited by the geometric intrinsic dependencies of the individual surface areas among themselves, so that there is only a narrow field of application for moldings formed in this way.

The object of the invention is (in an effectively feasible solution proposal for industrial production three-dimensional

Shaped semi-finished flat products on the material basis of wood and fiber materials.

OBJECT OF THE INVENTION The production of a flat, three-dimensionally bendable, wood-based material, which during

the forming process does not tend to wrinkle or wrinkle. At the same time, the wood-based material should be no breakthroughs and

Have incisions that completely durchstrennsp the material in the thickness direction and a consuming »reworking of the Make workpiece after the forming process necessary. According to the invention the object is achieved by the features of the characterizing part of the main claim. The three-dimensionally deformable surface element is over the entire surface or partially divided into strips, which with respect

their strip longitudinal extent according to the bending line course of a later intended surface elements ·

Forming are oriented and which a ratio of strip width to strip thickness or surface element thickness of

0.5: 1.0 to 5.0: 1.0.

Alternatively, the surface element in a comparable manner of parallel strand materials such as willow or Paper knitting consist. The cohesion of adjacent, parallel Lamoiien is realized by altornatlve solutions. So is next to one

punctiform gluing of adjacent elements, which may also be designed as reversibly releasable adhesive joints, as well as a mechanically destructible Querverburid possible, which allows a directed destruction of individual, adjacent layers during the forming process. This idea is comparable to the principle of a predetermined breaking point on a fractured part, wherein the hot solution of a complete separation of the entire cross section I: ι each case

is avoided. ·

The joints in the interior of the composite material are not externally visible. Due to the location and arrangement

the needle- or strip-shaped parts of the thermoformable surface elements remain the joints during and after the

Forming externally closed. As an alternative way to improve the dqs together and the plastic flow behavior of the surface element

is a one- or two-sided coating provided with a planar adjuvant. This variant is particularly advantageous when high tensile stresses occur during the three-dimensional, plastic deformation in the outer edge zone.

An advantageous embodiment of the invention is shown in the dependent claim 2. In this case, the three-dimensionally deformable surface element is a one after the known per se fine-line Technologle

glued or unglued layer package produced semi-finished product with or without Thermoplastklebfugen between the strips of the surface element and with or without an applied to the wide surface of the surface element auxiliary.

By preferably using the applied on the wide surface of the surface element adjuvant can during

the shear forming stresses occurring in the edge zones of the surface element can be safely absorbed.

In further advantageous embodiments of the invention, the joints between the strips of the surface element scratches, Punching or sawing joints. The three-dimensional deformability of the sheet according to the invention is achieved as follows. The ratio of thickness to width of the strips of the sheet is such that the elastic bending of a single

imaginary strip in the direction of the surface element level similar to good. Realizing is like bending across this plane.

In the case of the use of cords or rods this is given in any case. Furthermore, with the inventive design of the surface elements ^ In the phase of transfer into the

three-dimensional shape, the Längsverschlebbarkeit the individual strips or cords against each other guaranteed (abolition of the cross-bond by [Re-JPIastifizierung or mechanical Zerstörunpder adhesive joints or

Splitting joint breaks between the strips or by overstretching, [re-] plastification or destruction of a u.U. .

behind glued flat auxiliary material), which is a geometric prerequisite for the bending deformability of the surface element with respect to the deformation component in the strip longitudinal direction.

A caused by the same time caused in the transverse direction deformation component conditional tearing or compression of the Surface element is characterized by the relatively slight transverse bending deformability of the individual strips (narrow strip width) or Cords safely suppressed in connection with their direct or indirect Streifenquerverbund. In short, an initial level and plasticized or even without special plasticizing measures

nachverformbares surface element is prepared for the purpose of achieving a joint and wrinkle-free bending deformation to the three-dimensional structure in such a way that it locally or the whole area in narrow, relatively laich or longitudinally and Querblegeverformbare strips, rods or cords with respective cohesion between the strips, rods or Strings is divided, which takes place in the phase of deformation to the three-dimensional structure within the limits of the differential deformability or the deformation components of the strips, rods or cords quasi a total areal distortion of the semi-finished in two (l) directions of space, which finally the actual

Ensures joint and wrinkle freedom of the finished three-dimensional end product. A difficulty in the pressing of extremely three-dimensionally shaped surface parts is, similar to the deep drawing of Sheet metal, the tendency to wrinkling during the phase of collapse of this usually used

two-piece molding tools. Ee is the phase in which the form has temporarily several degrees of freedom of uncontrolled, mostly due to stability problems emigration. (In two-dimensional pressing of plywood, stabilization takes place in this phase by passing through the respective natural bending line

Folding process, the molding also snaps into the imposed position uno Mobilized so also). At the on

The above-mentioned manner is divided into strips of veneer or surface element, but for certain variants completely absent tensile strength of the veneer or surface element transversely to the strip direction is added. This must, insofar as it is not provided by back-glued auxiliaries or transverse veneer layers, produced in any other way.

According to the invention, the bending deformation of the surface element by introducing appropriate Biegeverformungskräfte with simultaneous one or two-sided surface pressure of the output still

planar broad surface of the surface element with a frictionally engaged and to the extent shear-deformable, one or more times usable auxiliary material such as a soft rubber mat made,

which is mitverformt in the bending deformation of btegezuverformenden Flächenolementes, and / or it is carried out together with the resting mats bending deformation of Blegezuverformenden surface element in a known for such applications die with a closing speed of 15 to 300mm / mln.

According to claim 3, it is advantageous if the Flächenendruckbeaufschtagung the lead-forming surface element is realized by means of two Andruckmatten, between which there is a vacuum, which is maintained at the protruding edges of the mats preferably by means of known Oichtpasten and that the structure of the vacuum with or without Support is provided for a flat press acting on the layer package and heated at 30 to 160 ^° C. It is also advantageous if the surface pressure is achieved by acting on both sides of the surface element, in its kind known pressure sacks whose internal pressure is kept constant until the time of complete closure of the die halves by means of pressure relief valves. As a result, a sufficient frictional engagement between the outer layers of the surface element to be deformed and the surface of the pressurized, shear-deformable tools (pressure sacks, soft rubber mats) is generated. The invention will be explained below in several Ausfühnngsbeispielen. In the accompanying drawings show

Fig. 1 .: Apparatus for the production of three-dimensionally deformable veneer sheets Fig. 2: Top view of the device according to Fig. I

rig.3: Device for producing three-dimensionally deformable veneer leathers

Figure 4: Device of three-dimensionally deformable veneer sheets not the fine-llne technology Fig. 5: involute to a peeling block glued veneers Fig. 6: composite to three-dimensional deformable surface willow branches Fig.7: Apparatus for the production of three-dimensionally deformable surface elements made of paper knit Fig. 8: Three-dimensionally deformable surface element made of paper knit Fig.9: For the production of moldings with three-dimensionally shaped corner areas prepared laminated layers. example 1 The accompanying drawings are FIG. 1 and FIG. 2.

0.8 mm thick ash veneer 1 passes through a scoring knife gate 2 and is thereby supported by the guide roller 3. The 1.2 mm thick strip separated veneer 4 passes through a pair of rollers 5 and is thereby impregnated with a hot melt adhesive

Gauze 6 laminated. Thus, a three-dimensionally deformable veneer sheet 7 has been created. Example 2 The accompanying drawing is Fig. 3.

Two polyethylene beechwood cross-bonded red beech veneers 8 of thickness 1.2 mm are separated by means of a multi-blade roller blade 9 in each case in the longitudinal direction of the veneers 8 in 2.0 mm wide strips. The separation cut only detects the respective Roil knife 9 facing veneer layer. The resulting veneer leather 10 is three-dimensionally deformable.

Example 3 The accompanying drawing is Fig. 4. From 2.4mm thick poplar veneers a block 11 is folded and of which transversely to the surface of the veneers and

in each case a 1.2 mm thick surface element 7 is cut down along the fiber direction (by means of a veneer knife 12). Before each cut, the cut surface of the block 13 is coated with a faster-melting hot melt adhesive 14. The next cut is made after sufficient firing of the hot melt adhesive 14 so that the individual strips of the blown egg

Flächenelemerjtes 7 are fixed and thus creates a three-dimensional deformable surface element. Example 4

1.2 mm thick beech veneer is separated by means of a multi-blade roller blade 9 analogously to Example 2 in 2.0mm wide strips, which is interrupted by a corresponding design of the cutting each at a distance of 50 mm, the cut over a length of 6 mm. As a result, the strips remain coherent and can be separated by the application of shear forces in the subsequent three-dimensional deformation.

Example 5 The accompanying drawing is Fig. 5.

1.8mm thick beech peel veneers 20 are equivalent to the residual roll diameter of peel logs

Grain arranged axially and outwardly involute shaped close together and by means of contact adhesive together

bonded. The resulting block is on known round peeling machines to 1.8mm thick, three-dimensional deformable9in

Veneer processed in which the shear deformable strips have a trapezoidal cross-section.

• t

Examples The accompanying drawing is Fig. 6.

Enttrinded willow rods 21 glued together to form endless strands are joined tightly together to form a closed surface of 450 mm width, provided with a thermosetting adhesive by means of rollers, held between a number of transverse forks 22 with a not yet cured adhesive, and separated from the previously arranged willow rod strands by a transverse separating cut , It has emerged as a three-dimensional deformable willow rod surface element.

Example 7 The accompanying drawings are Flg. 7 and FIG. 8. A number of paper knits 15 are combined on a roll to form a closed sheet 17 and i

then irreversibly glued with a very loose, thin fabric 16. The thus fixed surface element 17 is deformable three-dimensionally.

Examples The accompanying drawing is Fig.9.

2.0 mm thick veneers 18 are cut at the corners by punching cut so that parallel strips 19 arise.

The directions of the strips 19 of the three veneers 18 are perpendicular to each other. The thus prepared veneers become

then glued by means of a replastifizierbaren adhesive such as polyethylene and thus form a three-dimensionally deformable in the corner areas surface element 18th

According to the same basic principle of three-dimensional deformability, surface-isotropic plate materials can also be partial

be deformed three-dimensionally deformed by e.g. cut by sawing and each layered crosswise. However, it should be noted here that the strength of the cut-in area transversely to the cutting direction, which plays no role in the use of wood, is lost.

Example 9

A ply material of each with the wood direction perpendicular to each other arranged 1.8 mm thick and divided into 2.2 mm wide streaks veneer of the format 380 mm x 500 mm, the total thickness of 9 mm and a 0.2 mm thick glued joint made of polyethylene between the Veneering is brought to a temperature of 175 ⁰ C by means of a flat press and then pressed in a cold press die to form a three-dimensionally shaped, saddle-shaped backrest part. The prior Polyäthylenverklebung allows both the displacement of the veneer sheets on each other and the displacement of the 2.2 mm wide strips with each other, without the joints of said elements open during the closing of the Preßgesenkes. The closing of the die is carried out at a speed of 50 mm / min, so that the shear forces do not cause buckling of the moldings during the press closing.

Example 10

1.2 mm thick layers of strips divided into 1.5 mm wide, and connected by means of hot melt adhesives are sized with a known Kararnstoff-Formaldehydharzleim in the usual manner and with respect to the wood fiber direction each stacked vertically, so that a five-day veneer package is formed. This veneer package is placed between two 1.5mm thick soft rubber sheets, the protruding edges of which are compressed by means of a sealing paste. Vacuum is applied to the space inside the rubber sheets, possibly with the help of a flat press. At the same time preheating dos veneer packet to a temperature of 60 ⁰ C, through the layers, the hot-melt adhesive occurs easily schubverformbar. The thus prepared Preßpaket is placed in a cuf 12O ⁰ C heated, dome-shaped Preßgesenk which is closed at a speed of 200mm / min. By the vacuum, a frictional force between the veneers is produced, which allows the displacement described in Example 9. After curing of the adhesive, the molding is removed and the enveloping rubber removed, which compensates for the remaining vacuum. The resulting dome-shaped molding is used as a component of a container furniture.

Example 11

Veneer layers according to Example 10, but instead stabilized by means of hot melt adhesive with a gauze, are glued with urea-formaldehyde resin and pushed into a molding press. The die of this press has the shape of a three-dimensional seat angle. Above both die halves a pusher bag is arranged in each case. After the package has passed between the pressure bags, di9se be pressurized, so that the veneer layers are first pressed together without form compulsion. Thereafter, the die halves are closed, wherein the gas pressure in the pressure bags is kept constant by means of a pressure relief valve.

During the increasing effect of Gesenkflächen on the Pakei. nd the deformation associated with the pressure bags stabilize the molding analogous to Example 10. When fully fed Gesenk the pressure bags are double-walled on the pressing surfaces of the die halves and thus increase the heat transfer between the heated die and molding. After the end of the pressing a statically favorable, provided with circumferential Randaufkantungon seat angle has arisen.

Claims (3)

1. Three-dimensional bending deformable surface element on the material basis of wood and fiber materials, characterized in that the surface element (6,7,10,17) over the entire surface or partially divided into strips (4,19), which with respect to their strip longitudinal extent corresponding to the bending line course of a later intended Flächenelementenformgebung are oriented and which have a ratio of strip width to strip thickness or surface element thickness of 0.5: 1.0 to 5.0: 1.0 or that the surface element (6,7,10,17) in comparable Way of parallel strand materials such as willow rods (21) or paper knitting (15) and that a pointwise or completely, reversibly detachable or only mechanically destructible, direct or indirect cross-connection between the strips (4,19), rods (21) or cords ( 15), which by thermosetting, elastomeric or thermoplastic Fugenverklebung and / or by a thread backsetting such as zig-zag thread stitching and / or by back-side coating with a flat auxiliary material, such as a textile fabric (16), a nonwoven or a thermoplastic, elastomeric or reversibly hardening adhesive film and / or by dividing a surface element into strips with short strip interruptions and / or by a plate material (8) connected to the surface element and / or by further plate (s) (8). 2. Three-dimensionally bendable sheet element according to claim 1, characterized in that the surface element (7) according to the known fine-line technology from a glued or u η bonded layer package (11) generated semi-finished with or without Thermoplastklebfugen (14) between the strip of the surface element (7) and with or without an on the wide surface of the surface element (7) applied excipient (14). 3. A method for bending deformation of a three-dimensionally deformable surface element according to claim 1 or 2, characterized in that a surface pressure dej to be deformed surface element is realized by means of two pressure plates, between which there is a vacuum, which at the protruding edges of the mats preferably by means of known sealing pastes is maintained and that the construction of the vacuum made with or without the assistance of an acting on the layer package, heated with 3O ⁰ C to 16O ⁰ C flat press and that the subsequent deformation of the surface element in a known die with a closing speed of 15 mm / min to 300 mm / min is performed.