A COMPOSITE BODY AND A METHOD FOR MAKING THE SAME

A COMPOSITE BODY AND A METHOD FOR MAKING THE SAME

The present invention relates to a method of making a composite body, which may, for example, form or form part of a furniture frame or another supporting and/or decorative structure.

It is well-known to make furniture frames or frame parts from wood laminates comprising mutually superposed cr superimposed laminae of wood and intermediate layers of a settable or hardenable binder or glue. When the laminae have been mutually superposed, the laminate may be bent or curved to a desired shape prior to setting or harden- ing of the binder or glue. The laminate may, however, be bent or curved in a single direction only, viz. in a direction transverse to the layers or laminae. It has also been proposed to combine such bending with twisting. However, the shapes which may be made by con¬ ventional wood laminate shaping techniques are seriously limited.

The present invention provides a method of making an elongated, com¬ posite body which may be given a shape of double curvature, if de¬ sired.

Thus, the present invention provides a method of making a composite body, said method comprising making a first laminate from mutually superposed first laminae of material and intermediate layers of a first binding material, slicing said first laminate in a direction transverse to said first laminae, so as to produce second laminae, and making a second laminate from said second laminae by mutually superposing the same with intermediate layers of a second binding material.

It is understood that the composite body made by the method according to the present invention will comprise a plurality of substantially parallel extending strings of material having a small rectangular or parallelogram-shaped transverse cross section which are intercon- nected by first and second layers of binding materials. The first and second layers of binding material or glue, which are preferably of the same type, may, for example, be of a kind which may be softened, for example by heating and/or wetting. In such a case, an elongated composite body which has been made by the method according to the present invention may later be bent or curved to any desired shape of single or double curvature.

In the preferred embodiment, however, prior to setting or hardening of the first layer of binding material and prior to slicing, the first laminate is bent, wherein the direction of slicing is trans¬ verse to first generatrices of curvature formed by such bending. Similarly, prior to setting or hardening of the second layer of binding material, the second laminate may be bent, so as to form curvature thereon having second generatrices extending transversely to said first generatrices. As a result, a composite body being made by the method according to the present invention may be given a desired shape of single or double curvature while the composite body is being made and. before setting or hardening the binding material or glue, which may, for example, be of the thermo-setting type. The subject bending operations may then take place in suitable moulds or shaping tools in which pressure and heat is imparted to the first and second laminates, respectively.

The first laminate may be sliced in a direction forming an acute an- gle with the first laminae, whereby the composite body produced will include a plurality of strings or columns of material having a paral¬ lelogram-shaped transverse cross section. In the preferred embodi¬ ment, however, the first laminate is sliced in a direction substan¬ tially at right angles to the first laminae, whereby the said strings of material will obtain a substantially rectangular cross section.

The first laminae and/or the second laminae may have different thick¬ nesses, if desired. However, the thickness is preferably the same for all of the first laminae, and this is preferably also the case for all of the second laminae. The thickness of each of the first laminae may differ from or be the same as the thickness of the second lamin¬ ae. In the latter case the strings of material present in the com¬ posite body formed will obtain a uniform, substantially square cross section.

In principle, the said first laminae may be made from one or more of any suitable, bendable materials, such as plastics material and met- al, and the first laminate may include fibers, which may, for exam¬ ple, be reinforcing fibers incorporated in laminae of plastics mate¬ rial and/or in the building materials. When the fibers in the first laminate extend in substantially the same direction, the first lami- nate is preferably sliced substantially in the direction of said fibers, whereby the fibers will extend in the longitudinal direction of the plurality of strings of material present in the composite body formed. In the preferred embodiment of the method according to the invention, at least some, and preferably the majority, of said first laminae are made from wood, and said fibers are wood fibers. For the sake of strength and/or for decorative purposes some of the said first laminae may be made from metal or plastics material having a colour different from the colour of the wood laminae.

The thickness of the slices or the second laminae which are cut from the first laminate may be chosen in dependency of the extent to which the second laminate is to be curved or bent. In one example of the present invention, the thickness of each second laminate is normally 1-5 mm.

The method according to the present invention may be used for making composite bodies of a great variety of shapes of single or double curvature and for any of a number of purposes. Such composite bodies may, for example, constitute or form part of supporting and/or deco¬ rative structures, portals, frames of any kind, etc. It is believed at present that the method according to the invention is especially advantageous within the furniture industry for use in making furni¬ ture frame structures or parts thereof.

The present invention also provides a composite body being a laminate of mutually superposed first laminae of material and intermediate layers of a first binding material, said laminate being divided into co-extending second laminae extending transversely to said first laminae with intermediate layers of a second binding material.

The invention will now be further described with reference to the drawings, wherein Fig. 1 is a front perspective view of a first chair having frame parts made by the method according to the present invention, Fig. 2 is a side elevational view of a planar wood laminate, Fig. 3 is a front perspective view of the laminate of Fig. 2 bent into a substantially U-shaped member,

Fig. 4 is a front perspective view of the U-shaped member of Fig. 3 shown sliced so as to provide a plurality of U-shaped laminae, Fig. 5 is a front perspective view of laminae of the type made in Fig. 4 arranged in a press mould for producing a chair frame blank for a chair such as that shown in Fig. 1,

Fig. 6 is a front perspective view of the mould of Fig. 5 in its closed condition,

Figs. 7 and 8 are enlarged scale, transverse cross-sectional views of the frame of the chair shown in Fig. 1, Fig. 9 is an enlarged cross-sectional view of the U-shaped member produced by the slicing operation illustrated in Fig. 4, Fig. 10 is a second chair having frame parts made by the method according to the invention, and Fig. 11 illustrates a final bending and pressing process for making a chair frame blank for the chair shown in Fig. 10.

For purposes of description herein, the terms "upper", "lower", "right", "left", "rear", "front", "vertical", "horizontal" and deri¬ vatives thereof shall relate to the invention as oriented in Fig. 1. However, it is to be understood that the invention may assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodi¬ ments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.

Fig. 1 shows a chair 10 having exposed frame portions 11 which is produced by the method according to the present invention. The frame portion 11 may further comprise frame portions (not shown) which are covered by upholstery 12 and connected to the exposed frame portions 11 in any conventional manner.

The exposed frame portions 11 shown in Fig. 1 may be made from a planar piece of a wood laminate 13 as that shown in Fig. 2. The laminate 13 is made up by a number of planar, wood laminae or veneers 14 and intermediate layers 15 of a binder or glue. The planar, wood laminate 13 shown in fig. 2 may be bent so as to form a member 16 as that shown in fig. 3, which may be substantially U-shaped as shown, or which may be bent into any other desired shape of single curvature by use of a conventional bending technique. Thus, the bending may take place in a press tool or press mould comprising heating means for heating the laminate 13 during the shaping operation. The lami¬ nate 13 is preferably bent or shaped prior to hardening or setting the layers 15 of binder or glue, which may be of the thermo-setting type. This means that heating of the bent laminate 13 in the press tool or mould by the said heating means causes the glue or binder of the laminate to set after the laminate 13 has been shaped into the U-shaped member 16.

After bending, the U-shaped member 16 is sliced or cut longitudinally into relatively thin slices 17 by means of a conventional cutting or sawing tool. As seen from the end view shown in Fig. 9, each of these slices is made from juxtaposed, co-extending wooden string members 18 having a substantially rectangular or square cross section and being bonded together by the binder or glue layers 15. It is to be under- stood that the laminate 13 is preferably bent transversely to the longitudinal direction of the fibers of the wood material in the wood laminae 14, which means that in the slices 17 the wood fibers extend substantially in the longitudinal direction of the string members 18. A plurality of the slices 17 are then mutually superimposed with intermediate layers of a hardenable or settable binder or glue to form a second laminate, which as discussed in detail below, may be bent or curved in a direction transversely to the plane of such laminae by using a procedure similar to that used for shaping the member 16 shown in Fig. 3. Thus, any desired shape of double curva- ture or three dimensional part may be obtained. Figs. 5 and 6 illustrate how the exposed frame portions 11 of the chair 10 shown in Fig. 1 may be made from U-shaped slices 17 as those shown in Figs. 4 and 9. A suitable number of the U-shaped slices 17 are arranged on a base member 19 of a press tool or mould, which is generally designated by the reference numeral 20. The slices 17 are arranged in a stacked or mutually superimposed relationship with intermediate layers 21 (Figs. 7 and 8) of a binder or glue. In the example shown in Fig. 5, the frame assembly comprises at least four separate slices 17, including a lower slice 23, an upper rear slice 22, and two, upper forward slices 24. The free end portions of the upper, rear slice 22 are bent upwards. The upper, forward slices 24 may be made from slices cut from a planar, wood laminate as that shown in Fig. 2, and are shown arranged in engagement with the free end portions of both upper rear slice 22 and lower slice 23. Trian- gular splines 25 may be inserted in the spaces formed where slices 22, 23 and 24 come together and join, and glue or binder is applied not only between the adjacent slices 22, 23 and 24 of the contacting surfaces of the splines 25. The laminate structure thus formed may be pressed into the desired shape by means of movable tool or press members 26, 27, and 28 which may be moved in directions indicated by the arrows in Fig. 5 into a closed position, as shown in Fig. 6. When the laminate structure has been pressed into the desired shape as shown in Fig. 6, the glue or binder is hardened. Thus, in case the binder is of the thermo-setting type, the structure may be heated in the tool, for example by high frequency heating. In the press tool 20, the free end portions of slices 22 and 23 are combined with the laminate 24 so as to form leg portions 29, while the connecting or web portion 30 of slices 22 and 23 form the back 31 of the chair frame shown in fig. 1. When the glue or binder has been set, the frame structure blank thus formed may be removed from the press tool 20 and the surface of the blank may be ground or machined to obtain a desired surface finish and/or cross-sectional shape, for example an elliptical shape as shown in Fig. 7. If desired, the surface of the frame structure produced may be covered by a layer of veneer 32 or by any other desired surface layer.

Fig. 10 shows a second embodiment 33 of a chair having forelegs 34, hind legs 35, arm rests 36, a seat 37 and a back 38. The upholstered seat 37 and back 38 as well as the curved hind legs 35 may be made by conventional furniture making methods. Thus, the back 38 may contain a curved inner wooden plate, but this plate as well as the hind legs 35 are of single curvature so that they may be shaped by using con- ventional methods. However, the oppositely arranged forelegs 34 and arm rests 36 are interconnected by a connecting part 39 extending behind the chair back 38 so that the forelegs, the arm rests and the connecting part form a single integral frame part 40 of double curva¬ ture. This frame part 40 of double curvature may be made by the method according to the invention.

A chair frame blank 41 (Fig. 11) may be made from U-shaped slices 17 produced as described above with reference to Figs. 2-4. Fig. 11 illustrates press tool parts 42 and 43 having shaping surfaces 44 and 45, respectively, which are complementary to. the opposite outer surfaces of the frame blank 41. The tool part 42 is made from sepa¬ rate elements 48, while the tool part 43 is made from elements 49 and 50. These elements are clamped together by means of bolts 46 and 47, respectively. The frame blank 41 may be made by arranging a U-shaped laminate composed by U-shaped slices 17 and intermediate layers of a binder or glue between the shaping surfaces 44 and 45 of the press tool parts 42 and 43 as illustrated in Fig. 11. When the tool parts are moved to a closed position, the U-shaped laminate may be exposed to a high pressure, and the binder or glue may be set while the laminate is under pressure, for example by heating the laminate by high-frequency technique.

As mentioned above, the laminae 14 of the laminate 13 shown in Fig. 2 are preferably made from wood. However, for reasons of strength and/or in order to obtain a decorative surface pattern of the final product, some or all of the laminae may be made from other materials, such as metal or plastics material.

EXAMPLE 1

A chair frame as that illustrated in Fig. 1 may be produced as fol¬ lows: On the basis of a model or a drawing the accurate shape of the for¬ ming surfaces of a press mould used for shaping the U-shaped member' 16 shown in Fig. 3 and the forming surfaces of the press mould or tool 20 shown in Figs. 5 and 6 may be determined by using convention- al CAD/CAM technique. A plane wood laminate is made from layers of veneer and intermediate layers of a thermo-setting, two-component urea glue. The veneer thickness is selected in dependency of the degree of the subsequent bending, but may, for example, be 1-2 mm. The plane laminate thus produced is bent so as to form a U-shaped member as that shown in Fig. 3 in a conventional press tool or press mould. The U-shaped member is heated by high-frequency technique while retained in the press mould under pressure so as to set the glue. As an example, the spacing of the legs of the U-member may be about 380 mm.

When the U-shaped member has been removed from the press tool, the member is cut into U-shaped slices 17 by means of a rotating sawing or cutting tool comprising a shaft and a plurality of equidistantly spaced cutters mounted thereon. The cutting edges of the cutters may be provided with cutting diamonds, and the cutting tool may be rota- ted at a rotational speed of about 5000 rpm. By means of a cutting tool of the type described the U-shaped member shown in Fig. 3 may be sliced so that smooth cutting surfaces, without miscolouration due to undue heating, are provided. The thickness of each of the U-shaped slices 17, which substantially corresponds to the spacing between adjacent cutters of the cutting tool, is chosen with regard to the degree of bending in the subsequent bending process. The thickness of the slices are, however, normally chosen in the range of 1-5 mm.

The U-shaped slices 17 and wedge-shaped members or splines 25 are now arranged in a press tool or mould as that shown in Figs. 5 and 6, and a thermo-setting, two-component urea glue (Casco No. 1203) is applied to adjacent surfaces of the slices 17 and the splines 25. When the necessary number of slices have been arranged in the press tool 20, the tool members 26, 27 and 28 are moved to their closed position shown in Fig. 4, and a pressure of about 80 tons/cm^ may be applied to the laminated sample for about 180-300 seconds. The sample is simultaneously heated by high-frequency so as to set the glue while the sample is under pressure. After hardening of the glue, the sample is removed from the press tool and may then be allowed to cool while supported by a supporting device having supporting surfaces which are complementary to the surfaces of the sample. The finished sample may then be arranged in a CNC (computer numeric control) , five axes machining centre or in another computer controlled cutting machine, or the sample or blank may be finished by any other manner to obtain the desired final outer shape and finish of the furniture frame part to be produced.

EXAMPLE 2

A chair frame blank 41 as shown in Fig. 11 may be made by slicing a U-shaped member 16 (Fig. 3) as described in Example 1 above. The thickness of each of the wood laminae 14 in the laminate 13 (Fig. 2) may be 1-1.5 or 2 mm, and the thickness of each of the slices 17 (Fig. 4) may be 1-5 mm, preferably 1.5 mm. The slicing is made by means of a cutting device as that described in Example 1. The glue used for binding the slices 17 together to form the chair frame blank 41 is a thermo-setting, two-component urea glue, which is applied to the surface of the slices in an amount of 100-120 g/irr^• The pressure applied by the press tool parts 42 and 43 and the pressing and sett¬ ing time as well as the cooling procedure are the same as described in Example 1. The chair frame blank 41 thus produced may be machined or otherwise processed so as to produce the frame part 40 with the desired shape and surface finish, for example in a CNC, five axes machining centre.

In the foregoing description, it will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed herein. Such modifica¬ tions are to be considered as included in the following claims, unless these claims by their language expressly state otherwise.