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(11) Patent Number: KE 71
(45) Date of grant: 27/01/1999
 
(12) PATENT
 
(51) Int.C1.5: A 47B 96/20
(21) Application Number: 1995/ 000165
(22) Filing Date: 07/06/1995
 
(73) Owner: RAMBOO COLOUR CANE LIMITED. of, P 0 BOX 28687 NAIROBI., Kenya
(72) Inventor: MR. BARENDER KALSI ANDMRS MONMOHAN KALSI
 
(54) Title: PVC AS FURNITURE MAKING MATERIAL
(57) Abstract:
The invention relates to the [production of tubular articles made from synthetic thermoplastic materials , whirls resembles wood ,rattan , bamboo cane reed , wicker, rush hickory and similar natural materials, and also thermoplastic materials which replace the natural materials mentioned above, colouring and veining such materials and also joining and securing by means of ties made from rigid, or semi rigid , or plastified polyvinyl the natural and artificial materials above mentioned for the purpose of assembling furniture and structures in general.
 
PROCESS TO MANUFACTURE TUBULAR ARTICLES RESEMBLING WOOD, CANE, BAMBOO, REED, RATTAN, RUSH, HICKORY AND THE LIKE
This invention relates to the production of tubular articles made from synthetic thermoplastic
materials, which resemble wood, rattan, bamboo, cane, reed, wicker, reed, rush hickory and similar natural materials, and also to the production of furniture, structures and every kind of ornament in general employing thermoplastic materials which replace the natural materials mentioned above, colouring and veining such thermoplastic materials, and also joining and
securing by means of ties made from rigid, semi-rigid, or plastified polyvinyl the natural and artificial materials above mentioned, for the purpose of assembling furniture and structures in general.

FIELD OF THE INVENTION
This invention relates to the tubular plastic furniture and to a method of making the furniture. The invention is additionally concerned with making tubular plastic furniture which has the appearance of natural cane, bamboo, wood, wicker or the like.
BACKGROUND TO THE INVENTION
Natural cane, as is the case with most natural products, is becoming scarce and therefore expensive and yet remains a desirable product for the manufacture of furniture.
Furniture made from plastic tubing is also currently popular of its relative cheapness compared to timber furniture. The disadvantage of tubular plastic furniture is, however, the unsightliness of the joints between the various tubular components which for reasons of strength are sleeved joints which resemble plumbing fittings.
OBJECT OF THE INVENTION
It is the object of this invention to provide tubular plastic furniture and a method of making the furniture and more particularly making the furniture to have the appearance of cane, bamboo and wood.
SUMMARY OF THE INVENTION
A method of making tubular plastic furniture according to the invention includes the steps of
joining a first tubular element to a second at a position in its length by providing a hole in the wall of the second element at the position of the join, attaching the first element to the second with the bore of the first element in communication with the bore of the second through the hole in its wall and filling the bores of both elements at least in the zone of the join with a settable material.
Further according to the invention the method includes the step of locating suitable reinforcing material across the join in the bores of both tubular elements prior to filling the bores of the elements with the settable material.
A method of giving a tubular plastic element the appearance of natural cane according to the invention includes the steps of grooving the outer surface of the PVC element to resemble natural cane.
Preferably, the method includes the step of heating lengths of the element to soften the plastic and expanding the softened portions of the element radially to provide the element with the appearance of a jointed cane stem.
According to the invention there is provided tubular plastic furniture which includes tubular elements which are joined according to the above mentioned.
Further according to the invention the tubular elements are provided with a natural cane 15    appearance by the above method.
BRIEF DESCRIPTION OF THE DRAWINGS 
The invention is now described by way of example only with reference to the drawings in    which: FIGURE: 1 is a schematic side elevation of the apparatus for deforming tubular plastic
elements to resemble natural cane,
FIGURE: 2 is a perspective view of a short length of a tube which has been deformed by the apparatus of Figure 1,
FIGURE: 3 is a sectioned side elevation of a join between two tubular plastic elements, and
FIGURE: 4 is a similar view of that to Figure 3 of a second embodiment of a join between two tubular elements.
DETAILED DESCRIPTION OF THE FIRST SET OF DRAWINGS
The tubular plastic material from which the furniture of the invention is made is PVC tubing
which has smooth inner and outer walls. In the first step of manufacturing the furniture of the invention the outer wall of the tubing is longitudinally grooved with the grooves having random depths as is the case in natural cane. The tubing may be grooved by a die during the extrusion process or may be scraped with a sharp instrument such as a saw blade which is held transverse to the axis of the tube while the tube is scraped. In the second stage of providing the tube with a cane appearance the tubular element 10 is laid in a guide which may consist of plurality of U-shaped support sections 12 which are held in longitudinal alignment on a bed which is not shown in Figure 1. Interposed between the ends of various lengths of the supports 12 are a spiral shaped heater element 14, a planar heat shield 16 which is holed for the passage of the tube and a spray booth 18.
In use, the tubular element 10 is fed along the supports 12 in the direction of the arrow in
Figure 1 until a short length of the element has passed through the heater 14. The heater is
then activated to soften the wall of the tube over the portion of its length which lies within the heater coils. The tubular element 10 is then upset by moving the tube portions on either side of the heater 14 toward each other to deform the softened portion of the tube radially outwardly as shown at 20. The upset portions 20 of the tubular element are more clearly seen in Figure 2. The tubular element 10 is then again fed in the direction of the arrow in Figure 1 to pass through the heat shield 16 and through a grommet in the outer wall of the spray booth 18 and into the spray booth where the still slightly softened upset portion of the tube is cooled by cold water sprays in the booth. When a suitable length of the tubing has passed through the heater 14 the tubing is again stopped and heated by the heater and again upset. This process is repeated at regular intervals over the length of the tube with a naturally jointed cane appearance. Instead of manually upsetting the tube 10 to provide the jointed bulges 20 the ends of the tube could be suitably blanked with an air hose passing through one of the blanks to pressurize the inside of the tube so that it would be expanded by the pressure air in the heater zone when the wall of the tube has become sufficiently softened. Provided the tube 10 is moved quickly enough through the Figure 1 apparatus the heater 14 could be left on and with the pressure air method of expanding the tube the apparatus could become almost fully automatic.
To construct furniture from the cane like tubular elements 10 suitable lengths of the elements could be joined as shown in Figure 3 and 4.
In figure 3 the join is made by holing a first tubular element 22 and grinding the free end of a second element 24 to a convex shape which is a snug fit over the outer wall of the tube 22. Heavy wire reinforcing elements 26 are then located in the bores of the tubes 22 and 24 to be located across the joint between the two tubes. The contact surfaces of the tubes could, and preferably are, coated with suitable PVC adhesive which will bond the two tubes together in their contact areas.
When the article of furniture has been completed liquid polyurethane foam or similar non-toxic foam is poured into the tubes and allowed to expand and fill the tubes with the foam material which is rigid when set. It is, however, not essential to the invention that the foamed material is rigid when set and it may txt desirable to use a slightly resilient material so that the joints of the furniture are slightly flexible.
In the Figure 4 embodiment of the joint the tube 24 has its free and convexly rounded to
conform to the radius of curvature of the inner wall of the tube 22 and has two holes 28 and 30 drilled through its walls to be in register on the axis of the tube 22. The tube 24 is then pressed into the hole in the wall of the tube 22, again preferably with suitable adhesive on the tube surfaces which abut each other in the joint and the tubes of the article of furniture are again foam filled so that the joint zones of the furniture tubes are homogeneously foam filled.

The Figure 4 embodiment of the join could, of course, also include suitable reinforcing elements which pass from the bore of the tube 22 across the join into the bore of the tube 24 to further strengthen the joint between the two tubes.
Both the Figure 3 and 4 joints are strip wrapped as are the joints in conventional cane
furniture. Preferably the wrapping strips are made of a suitable plastics material which may be tightly heat shrunk over the tubes at the joins.
 
The tubular elements 10 from which the furniture of the invention is made could be, and are preferably, coloured by a pigment which resembles natural cane in colour as closely as possible. The tubular elements may then be wiped with a fairly dark almost black coloured paint to fill the grooves in the outer wall of the tube and then either wiped or rapidly dipped in a lighter cane coloured paint to provide an authentic looking finish to the tubes.

The invention is not limited to the precise details as herein described and the tubular elements 10 could be made to represent lengths of bamboo as opposed to cane by simply expanding the upset portions 20 of the tubular element into contact with a heated ring to provide a circumferential groove in the centre of the upset portion 20 of the tube to resemble the grooved joints of bamboo. Additionally, to create more exact upset portions 20 in the tube the outer wall of the tube could be expanded into contact with the inner wall of a mould which could be suitably profiled to ensure that each of the upset portions of the tubes are identical. Also, the furniture joins of the invention are not limited to those illustrated in Figure 3 and 4 and the tube 24 of Figure 3 could, for example, carry on its inner surface and protruding from its free end a tubular spigot which is bonded to the inner wall of the tube 24 to protrude into the tube 22. The spigot then would, of course, require holes similar to the holes 28 and 30 in Figure 4 for reinforcing material, if required, and to enable the joint to be foam filled.
Up to the present time no process such as that of the present application has been known for producing articles similar to the natural materials above mentioned, what is known in the art is the production of pieces of cast metal or ceramics obtained by means of molds. The effort has been made to produce rigid plastic articles, similar to such natural materials. However, success has not been achieved in imitating bamboo, and the invention is accordingly limited to the reproduction of simulated bamboo.
Up to the present time pieces of furniture such as chairs, rockers, headrests, shelves, tables and  the like have been reproduced from rattan, bamboo and other natural materials, which have an extremely high cost and which require a great deal of maintenance, furthermore they cannot be used out of doors because of their low resistance to the elements, and are also easily broken, since these natural materials are not sufficiently strong to bear fairly great weight.
In the specific case of rattan, it is well known that this material is scarce, since it grows only in Eastern countries, and very expensive, it is also difficult to work and requires selection, finally the pieces made from it cannot be used out of doom.
Furniture made from natural materials, such as a chair or a rocker, generally include cushions  which are covered with cloth, other textile material, plastic, or leather, these cushions are supported by a reed or wickerwork woven structure built into the piece of furniture, presenting the same drawbacks as pointed out above. An additional problem arises from the method required for weaving wickerwork, since it must be kept submerged in water to give it flexibility and ease of manipulation. This method, besides being slow, is dirty, and there is always the risk of wetting delicate portions of the furniture.
The procedures of colouring or veining various articles of different materials such as ceramics and metal, and making them resemble the veining of wood, have consisted merely of colouring or dying the surface of the materials, later applying a coat of varnish or lacquer to provide a brilliant surface, or merely of applying on the surface thin layers of printed wallpaper that simulated the veining of wood.
These processes have the disadvantage that they are not very appropriate for application to thermoplastic materials, since paints or dyes generally do not show good adherence to these synthetic materials; and consequently the application on any solvent, however weak, or mere use and exposure produce deterioration and removal of the paint leaving the synthetic material exposed and unprotected.

The procedures known hereto for typing knots for this type of furniture, using straps or strips of rattan bark, reeds, rushes of raw hide have the drawback that they must be secured by means of nails or other device. These ties also have poor resistance to weathering, and also the tendency to stretch or shrink with changes of temperature, they also eventually get dirty, rot, and fail.
These systems of typing are very well known, as is the use of natural materials for carrying them out, as proposed.
In view of what is set forth above, it is the object of the present invention to produce articles which are identical to the eye and to the touch with those made of natural materials, such as rattan, bamboo, cane, reed, wicker, hickory and the like, but which are made of rigid thermoplastic materials having an appearance like that of the natural materials but being more durable and of comparatively lower cost than the said natural materials, and furthermore being easy to work in all sizes and diameters, and being susceptible of mass production in every type and colour desire of the natural material it is intended to imitate.
Another object of the present invention is to form protuberances which simulate the knotty and non-symmetrical portions, with ridges and marking, similar to the irregularities of the natural material. Once this phase has been completed, the tubular lengths are thermally molded, giving suitable shape to the sections which will make up the furniture and structures.
By means of the procedure for colouring and veining the synthetic thermoplastic materials of the present invention, all of the problems above mentioned are avoided since the paint or pigment with which the surface of the synthetic thermoplastic materials is to be coloured or grained is dissolved in a solvent effective upon thermoplastic material. If desired, when the pigment is dissolved in the solvent a small amount of the thermoplastic material itself which is to be veined can be dissolved, thus achieving a better adherence upon applying the colouring or veining applied to the surface of the synthetic thermoplastic material, causing the colouring or pigment to be absorbed into and form part of the material itself when the solvent evaporates. in this way they said pigment is intimately infused within the material and it is very difficult for the veining to be removed either by wearing always of the material, by the application of some light solvent applied to the surface, or by weathering.
The advantage is also obtained that these synthetic articles are light but strong and easy to
work, and present an appearance which is identical in looks and feel to the natural materials,and can be used indoors and outdoors with no maintenance. In imitations of wood graining, very rare and costly woods can be simulated avoiding the use of the natural materials, limiting importation and excessive exploitation of forests.
Another advantage of the present invention is that of providing a way of joining the furniture, structures and ornaments in general, whether of natural or synthetic materials, by means of typing them with narrow strips or ribbons of polyvinyl chloride. Before the tubular portions are tied, however, they have to be attached to each other by simple soldering, by attaching a plug or stopper and screw at the end of the other portions, or by other connecting means such as an injected plastic connector also attached to the ends of the tubes. Afterwards, a better and permanent fastening is obtained, for the reason that after the tie of PVC is heated by means of applying heat or microwave treatment, or without heat through the action of time at ambient temperature, it contracts permanently and provides a very firm and tight tie in an elastic manner. Such a tie will neither slacken nor release. Notwithstanding later application of heat or cold, and will not permit the joints to open. This characteristic is heightened by forming striations or grooves in one or both surfaces at the moment of extrusion to give the material greater adherence, and making it unnecessary to use any other means of locking engagement such as nails, staples, bonding adhesives and the like, it is necessary only to link the ends of the tie together suitably.
The stripes or ribbons of PVC can be molecularly oriented in the lengthwise direction, as is well-known in the field of heat-shrinking plastics under the term "memory", at the time of their extrusion, so that when heat, light or microwave treatment is applied, or through the mere effect of the ambient temperature they will undergo permanent shrinking thus tightening the tie made with this material.

The ties or ribbons of PVC can be coloured like the tubular sections to give them an appearance similar to that of natural materials such as reed, wicker, rattan, bark, cane, bamboo, hickory and the like, but lengthwise, as well as of rawhide strips etc.
The ties made of PVC also provide the important advantage that they do not rot nor permit
absorption of moisture nor dust. They can be used out of doors, giving a natural and aesthetically pleasing appearance and better resistance to weathering and stay tight even when the material tied expands or contracts, thus they give much firmer joints that natural materials known up to the present time.
The tie of PVC of the present inventing can be used on natural materials with the same advantages described above or firmness combined with a natural appearance. In the case of furniture made with natural or with synthetic materials which have cushions on the seat portion, the use of contractible PVC strip or ribbon of uniform base colour, with a cross- sectional shape which can be round, oval, flat or rectangular, in suitable lengths and widths as desired, upon which very fie lengthwise striations have been formed, and which has been given a grained appearance according to the method described above, affords the advantages already cited and others as well.
The interlacing which serves as base for the seats, or for structural or merely ornamental
purposes, can be made of PVC strip, with important advantages over natural materials. In
some pieces of furniture the tubular profile, knotted and veined, can be peripheral structure, and the interweaving performed with PVC strip will give the precise appearance of furniture made of wickerwork.
This interweaving has been tried with other materials and other techniques, but it has not been possible in these cases to get away from the artificial appearance.

Another additional advantage is that this material can be worked on when cold and dry, without the need for special treatments and without dirtying the piece of furniture, along with the advantages of tensioning and resistance to weathering already mentioned.
In the case of furniture made to imitate bamboo, the strips of split bamboo are replaced with similar strips of PVC extrusion and a plank can be formed and incorporated into the piece of furniture, texturizing it with striations and veining it in the manner already described.
The materials that are imitated according to the instant invention belong most of them to the grass family and are known for their following characteristics:
(1) Bamboo (technical name Bambusaceae), - tall plant with hard, hollow, jointed stems
of the grass family, stem, used as a stick or support.
(2) Rattan (technical name Clamus Rotang). - East Indian palm tree with a cane like stem.
The commercially called reed used in the manufacture of chairs, baskets, etc, is the split inner portion of rattan in cylindrical form, like true reeds.
Rattan is usually known as reed, when used for woven furniture (Encyclopedia Americana).
The rattan vine is harvested by natives, then cured and classified as to size and texture, the bark is removed and treated, thus becoming "cane" and used most extensively as seats for chairs.
The wood part of the rattan vine inside the bark is treated and the finished products are known as reed, while being woven, reed is kept in water so as to make it pliable.
The lack of willow and the dissatisfaction over reed owing to its brittleness has caused furniture and basket makers to seek a new article. (Encyclopedia Americana)
Rattan - stems (collectively) as used for building, basket work, furniture, etc.
BRIEF DESCRIPTION OF THE SECOND SET OF DRAWINGS
The characteristics features of the present invention are also shown in the following description and in the drawings which accompany it.
FIG 1 is a view in lengthwise elevation showing the stage of applying heat and pressure to produce the knotty sections in a tubular portion.
FIG 2 is a view in lengthwise elevation showing a tubular portion with the typical joint shape
produced.
 
FIG 3 is a view of a finished length which has been coloured, engraved and slotted, with markings on the mode.
FIG 4 is a view of finished portion which has been coloured, engraved and slotted, showing divisions and markings of an article resembling bamboo, rattan, cane or the like.
FIG 5 is a view in elevation of two tubular lengths of thermoplastic synthetic material joined in a T. showing one way of tying or joining the lengths.
FIG 6 is a view of showing two tubular portions of synthetic thermoplastic material, indicating another manner of typing the tubular portions together.
FIG 7 is a view in conventional perspective of a finished piece of furniture showing the lengths of PVC which have been coloured, veined, bent, brought together and tied with PVC strip.

FIG 8 illustrates an extrusion die and a travelling mold installation.
FIG 9 illustrates the travelling molds in their travelling operation.
FIG 10 illustrates one end view of one travelling mold in its closed position.
 FIG 11 illustrates a travelling mold and end view in its open position.
FIG 12 illustrates a travelling mold in its open position such as that if FIG 11 in a conventional perspective views.
FIG 13 illustrates a travelling mold of FIG 9 in their travelling operation showing the molds in their close, open and semi closing positions.
FIG 14 to 17 illustrates various manners by which the extruded tubes are connected before
they are tied to form the structure of the invention.
FIG 18 illustrates a slotting mold by which the surface of the extruded tube is slotted.
FIG 18 A is a detailed view of section A of FIG 18 illustrating how the slots are formed on
the tube surface.
FIG 19 illustrates a manual version to slot the surface of the tubes by a file used manually.

Referring now to the drawings, the procedure for producing synthetic articles identical is appearance and to touch with rattan, bamboo, cane, reed, wicker, rush, hickory and similar natural materials according to the present invention consists of forming a tubular length 20 out of a rigid or semi-rigid thermoplastic material in any suitable colour by a suitable tube making process, preferably by extrusion, which has the advantage of being seamless. The said tubular section 20 is chilled and becomes rigid, heat is then applied to selected portions of lengths 20 and pressure is applied from the sides as shown by arrows for the purpose of deforming the heating profile 22 outward, simulating nodal formation 25, as is shown in FIG 2 when the wall of the tubular portion is very thin, it is desirable to introduce a shaper (not shown) inside the tube, to prevent it from warping or sucking in as the modal portions 25 is formed. Tubular section is then cooled again, along with nodal portion 25, and the tubular portions are then coloured and veined again as required portion of tubular material 20 is again heated at the desired points to give it the shape and the bends required.
For producing articles similar to cane, reed, bamboo, or wicker, grooves 24 are made, as well as spiral striations 26 and circular shallow incisions 27, in the selected portions, immediately after heating and before forming node 25 to simulate the separation of the joints in the natural material and also portion 28 which is caused when the leaf is torn from the trunk of the natural cane, reed, or similar stem in natural materials, etc, by applying pressure to form the node and expanding the striations and incisions slightly.
The formation of the tubular length can be made by any known process, but as indicated above extrusion is preferred because it does not leave visible seams.
In one embodiment invention a thermoplastic tube 20 as illustrated in FIG 8 is extruded as per extruder 40 and die 40 through whose central portion two pulley wheels 42 are held which are separated from each other by a smaller distance than the length of the travelling molds 36. Likewise, a tubular duct is connected to the die entering systems while leaving air exit 43 between the two pulley wheels. The speed of the travelling molds is adjusted to coincide with the speed of the tube being extruded. The motion of the travelling mold as carried out by conventional motion means 39, and when one of the molds 36 is exactly below tube 20, the mold closes surrounding the tube while pressured air is fed through duct 41 leaving through exit 43, and as tube 20 is hot it will immediately take the shape of the mold because pulley wheels 42 prevent the air pressure to be lost at the same time cold water is circulated from entrance 38 of the mould and leaving through exit 38 by which tube 20 is cooled, taking the shape imparted to it by the mould whose cavity 37 produces the nodal portion 25. During this operation the tube portion is also calibrated. When the said mold and the tube portion inside it, have travelled a distance equal to the mold length, the latter closes upon the tube that coincides with it, and the whole operation is then repeated for each mold in order to form other nodes and calibrating the tube portion. One the tube portions are extruded as above, they are cut in desired lengths or they may be bent so as to have them ready for assembling the desired structures. However, before they can be tied together to form the pieces of furniture, such as illustrated in the enclosed photographs, they have to be connected by using connecting means such as illustrated in FIG 14 that shows plug 45 and plug 45' as shown in FIG 16. They can also be connected by welding such as welding element 46 of FIG 15 or by the screws 47 and the plug 48 combination as shown in FIG 17. After the portions are connected as indicated above they can be tied as per FIG 5 to 7.
According to the invention another embodiment to be considered is that illustrated in FIGS 18 and 19 in the former of which small slots are produced on the outer surfaces of the tubes by the slotting die 49 whose slotting section 50 produces the slots that resemble the surface of natural materials as bamboo and rattan. However, such operation can be performed manually when smooth surface die is used, by using a file 51 such as that illustrated in FIG 19.
Deforming the heating profile 22 outward, simulating nodal formation 25, as is shown in FIG 2 when the wall of the tubular portion is very thin, it is desirable to introduce a shaper (not shown) inside the tube, to prevent it from warping or sucking in as the modal portions 25 is formed. Tubular section is then cooled again, along with nodal portion 25, and the tubular portions are then coloured and veined again as required portion of tubular material 20 is again heated at the desired points to give it the shape and the bends required.

For producing articles similar to cane, reed, bamboo, or wicker, grooves 24 are made, as well as spiral striations 26 and circular shallow incisions 27, in the selected portions, immediately after heating and before forming node 25 to simulate the separation of the joints in the natural material and also portion 28 which is caused when the leaf is tom from the trunk of the natural cane, reed, or similar stem in natural materials, etc, by applying pressure to form the node and expanding the striations and incisions slightly.
The formation of the tubular length can be made by any known process, but as indicated above extrusion is preferred because it does not leave visible seams.

In one embodiment invention a thermoplastic tube 20 as illustrated in FIG 8 is extruded as per extruder 40 and die 40 through whose central portion two pulley wheels 42 are held which are separated from each other by a smaller distance than the length of the travelling molds 36. Likewise, a tubular duct is connected to the die entering systems while leaving air exit 43 between the two pulley wheels. The speed of the travelling molds is adjusted to coincide with the speed of the tube being extruded. The motion of the travelling mold as carried out by conventional motion means 39, and when one of the molds 36 is exactly below tube 20, the mold closes surrounding the tube while pressured air is fed through duct 41 leaving through exit 43, and as tube 20 is hot it will immediately take the shape of the mold because pulley wheels 42 prevent the air pressure to be lost at the same time cold water is circulated from entrance 38 of the mould and leaving through exit 38 by which tube 20 is cooled, taking the shape imparted to it by the mould whose cavity 37 produces the nodal portion 25. During this operation the tube portion is also calibrated. When the said mold and the tube portion inside it, have travelled a distance equal to the mold length, the latter closes upon the tube that coincides with it, and the whole operation is then repeated for each mold in order to form other nodes and calibrating the tube portion.
One the tube portions are extruded as above, they are cut in desired lengths or they may be
bent so as to have them ready for assembling the desired structures. However, before they
can be tied together to form the pieces of furniture, such as illustrated in the enclosed photographs, they have to be connected by using connecting means such as illustrated in FIG 14 that shows plug 45 and plug 45' as shown in FIG 16. They can also be connected by welding such as welding element 46 of FIG 15 or by the screws 47 and the plug 48 combination as shown in FIG 17. After the portions are connected as indicated above they can be tied as per FIG 5 to 7.
According to the invention another embodiment to be considered is that illustrated in FIGS 18 and 19 in the former of which small slots are produced on the outer surfaces of the tubes by the slotting die 49 whose slotting section 50 produces the slots that resemble the surface of natural materials as bamboo and rattan. However, such operation can be performed manually when smooth surface die is used, by using a file 51 such as that illustrated in FIG
19.
 
Similarly, the node can be formed by inserting a suitable tool inside the tube to provide an outward deformation of the e heated potion, or air or gas under pressure can be applied inside the tube to cause the heated portions to swell and simulate joints. In the tubular length the nodes can be distributed either with regularity or irregularly as desire, by means of the methods indicated.
A mold to provide the desired external appearance of the node or joint or intermediate surface can be placed around the outside of the heated portion of the PVC tube, the exterior surface will take on the surface texture of the mold surface.
The external mold may also have pores or slots communicating with a vacuum source to draw
and squeeze the softened tube material there into for further simulation of ridges and protuberances of the natural material imitated.
Below examples are given of preferred processes for coloring and graining synthetic thermoplastic materials to cause them resemble wood, rattan and similar natural materials.
EXAMPLE 1
Tubular portions 20 are prepared by extruding PVC Thermoplastic material which already has a uniform base color similar to that of wood, as shown in FIGS 3 to 7 a layer of suitable solvent which may be either tetrahydrofuran or methylene chloride is then applied over selected portions 29, 30 of the said surface for the purpose of dissolving a very thin layer of the surface of the portion and the veining is then applied using a suitable pigment dissolved in the solvent itself which may be a mixture of (Hoechst Chemical Co.)
(1) Yellow Sol HR
(2)  Permanent Red TG -01
(3) T1 02
(4) Carbon Black
(5) Ca CO3 employing a suitable applicator such as cloth bag or brush, forming graining 29
or knobs 30 like knotty portions, finally, if desired, a light layer of varnish or a matte tone can be applied, or a mere coat of wax or matte lacquer.
EXAMPLE I A
The same procedure is an example 1 is repeated except that Acrylonitrile-butadiane-styrene copolymer is extruded and aceton is used as the solvent.
EXAMPLE 1 B
The same procedure as in Example 1 is repeated but polystyrene is the material extruded and thinner is used as the solvent. The pigment used is HOECHT's Orango L-404 mixed with Brown L-701.
EXAMPLE 2
Tubular lengths 20 of thermoplastic material are prepared with a uniform and integral base
colour similar to that of rattan: a solvent is applied over selected portions 29, 31 of the said surface to dissolve a light layer of material, and to this surface a suitable pigment is applied dissolved in the solvent itself, generally using pincers to produce the effect of knotty portions (not shown) and veins 29, the material is allowed to repose so the solvent will evaporate and thus allow the veining to form part of the stock itself, on its surface; finally if desired a light layer of varnish or lacquer may be applied.
EXAMPLE 3
Tubular length 20 are prepared with nodes, from a synthetic thermoplastic material having an integral base color similar to that of bamboo; a light layer of solvent is applied over selected portions (not illustrated) of the peripheral surface of the length for the purpose of dissolving a thin superficial layer of the surface, and manually spots and striations are applied around nodes 25, to give them the appearance of bamboo of the kind shown as Indian cane or Bengal reed.
Referring now to FIGS 5 and 6, detailed illustration is made therein of ties consisting of a strip of PVC 32 over a structure of natural material 20 in one embodiment of the present invention.
The strap of PVC 32 is of one piece and is secured by means of interlacing 38 suitably at its
ends which are tucked under, thus there is no need for using nails or tacks to secure it. PVC strap 32 exhibits striations’ 34 and gaining 35.
The strap of PVC 32 with the stated characteristics gives the precise appearance and tactile   sensation of a piece of furniture made entirely from natural materials and has also the
firmness and strength of polyvinyl chloride.
Longitudinal astriations 34 as formed on the strap of PVC used in this embodiment of the
invention at the moment of its extrusion or subsequently, with a suitable tool, Veining 35 is accomplished in a manner similar to that for the tubular sections described above, again
affording appearance and touch like that of furniture made from natural materials.
While the foregoing description is drawn to specific concrete embodiments of the invention, it will be understood by persons versed in the subject matter that changes in form and detail are within the scope and spirit of the present invention.
EXAMPLE 4
Tubular length 20 is extruded with required colour and wood graining properties are added are added prior to extrusion.
Wood graining is achieved right through the profile by adding 10% of darker material of
slightly different K. value and addition of silica formula to bring pigment to surface in streaks creating a wood grain effect.
 
What is claimed is:
(1) A method for producing artificial, tied tubular structures, the tying and the tubular portions of which have the appearance of natural materials, comprising the steps of:
Extruding a thermoplastic tubular material having base coloring, and wood graining
properties are added prior to extrusion (formula silica)
Separately extruding tying strips of basically colored thermoplastic material with striations formation on the surfaces thereof, longitudinally orienting the molecules of the material as it is being extruded whereby a molecular memory is imposed thereon, applying coloring to said strips of thermoplastic material by treating it with a solvent that at least partially dissolves said material, said solvent material having powdered polyvinyl chloride and a pigmenting material dispersed in it, whereby said thermoplastic material is made to resemble natural materials.

Heating preselected portions of the extruded tube after it leaves the extruding die and applying pressure to the heated portion to deform it so that the tube has deformed portions alternating with non-deformed portions.
Forming annular incisions in the hot deformed portions and peripheral striations as well as longitudinal incisions perpendicular to the said annular incisions and then cooling the tube.
Applying to the surface of the tube a solvent for the material of the tube

Pigmenting the extruded tube with pigment dispersed in the said solvent that has thermoplastic material dissolve in it so that the pigment will simulate veins on the surface of the tubular material.

Allowing the pigmented alternatively deformed tubular material to air-dry
Cutting the tubular material processed by the foregoing steps into desired lengths.
Heating it at selected points to bend tubular lengths as may be required, and letting it cool; attaching connecting means to the ends of said cooled tubular portions, and tying together the cut tubular material by means of said strips of colored thermoplastic material after connecting them in such manner as to produce structural portions of furniture, ornaments, and structures in general made of natural looking material such as wood, rattan, cane, reed, rush, bamboo, wicker, hickory and the like, the said strips becoming tightened when their oriented molecules recover their original position.

(2) The method according to claim 1, in which the portions of tubular material which are heated for deforming are located at irregular intervals along the tube, to deform which a pressuring means is inserted whereby pressure is applied from the inside surface of the heated portions forming protuberances in each of said irregular intervals.
(3) The method according to claim 1, in which the portions which are heated and distributed along the tube at intervals, are deformed into protuberances by means of 5    injecting gas under pressure from the inside of the tube.
(4) The method according to claim 4 in which the heated portions are subjected to suction applied to the outside surface, so that the atmosphere pressure will deform said portions into protuberance shapes.
(5) The method according to claim 3 in which the protuberance resulting from the application of pressure have a circular configuration resembling the knotty portions of natural materials such as wood, ratta, cane, reed, rush, wicker, hickory and the like.
(6) The method according to claim 1, in which the 10 connection of the cooled tubular
portions is performed by soldering.
(7) The method according to claim 1, in which the connecting means is a plastic stopper and screw combination whereby two separate tubular portions are connected as one of them carries the stopper as one of its ends and the other carries the screw across
its body.
(8) The method according to claim 1 in which the connecting means is an injected plastic connector assembly glued to the ends of the tubular portions.

(9) The method according to claim 1 in which the extruded tubular thermoplastic material is selected form the group consisting in polyvinyl chloride, high impact polystyrene and ABS (Acrylonitrile-Butadiene-Syrene Copolymer).
(10) The method according to claim 1, in which the connecting means is a plug piece
welded to the surface of one of the tubes and glued to the end of the other tube.
(11) The method according to claim 1, in which the connecting means is a plug piece that is screwed to the surface of one of the tubes and glued to the end of the other tube.
(12) The method of claim 1, in which the extruded typing strips are made of flexible polyvinyl chloride.
(13) The method according to claim 1, in which the solvent is selected from tetrahydrofuran, methylene chloride, acetone and thinner.
(14) The method according to claim 1, in which a knotty formation is produced by means of a travelling mold during the process of extrusion of the tube.
(15) The method in accordance with claim 1, in which the surface of the tubular portion
is slotted by means of a grooving extrusion die so that the resulting slotted portion
will simulate the superficial porosities of materials such as wood, rattan, bamboo, cane, reed, wicker, hickory and the like.
(16) The method as set forth in claim 15, in which the extruded tubular material is
manually grooved, so that it will simulate the surface porosity of materials such as wood, rattan, bamboo, cane reed, wicker, hickory and the like.
(17) The method as set forth in claim 1, in which the tube which is deformed under heat has a tool inserted as a core to prevent excessive contraction of the deformed portions.
(18) A method of forming a knot in an extruded tube comprising the steps of:-
(a) Extruding a thermoplastic material through a die, said die being incorporated
in a travelling mold and having an elongated central portion accommodating
two pulley wheels separated by a distance shorter than length of the cavity.
( b) Feeding air through an air duct of the die, expelling said air through an air exit situated between said two pulley wheels inside the extruded tube at a recessed cavity of the travelling mold when said mold travels at a speed adjusted to coincide with that of the tube as it is being extruded so that when the travelling mold is below the tube, it closed whereby said fed air causes the still hot extruded tube to adopt the shape of a knot by pressing it against said
recessed cavity, and
(c) Simultaneously circulating cooling water through the travelling mold thereupon
the extruded tube becomes rigid and the mold is open, leaving a nodal portion on the cooled tube.
(19) The method according to claim 18, wherein a continuous formation of knotty portions of the extruded tube are produced by carrying out the method utilizing an assembly comprising a series of molds.
(20) A two piece travelling mold wherein the two pieces of essentially symmetrical and hinged by the lower edge of their inner surfaces, having each of them a lengthwise cavity along their mid-portion, and at their canter of the cavity length there is an irregular deeper recessed cavity, said lengthwise cavity forming a molding duct when the mold hinged pieces rotate about their hinge so that their inner surface come together to close the mold.
(21) The travelling mold according to claim 20, wherein said two pieces have means of circulating water to cool them.

(22) The travelling mold according to claim 20, in combination with other similar molds
forming an assembly in which the molds travel attached to conventional motion means.

 

 

 

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