|Title of Invention||
A NEW TECHNOLOGY TO CONVERT BAMBOO INTO A SUBSTITUTE FOR NATURAL TIMBER
|Abstract||ABSTRACT The products of bamboo panels and bamboo wood having characteristics similar to natural wood, made by converting them from layers of bamboo and a process for manufacturing homogenous bamboo panels/bamboo wood of required dimensions from bamboo layer, in a simple cost effective manner by eliminating cracks and crevices caused by splitting and flattening, so as to have homogeneous layers of bamboo, the edges of the layers to be sized so as to render the edges straight and parallel, which layers are integrated into a continuous rigid mat, the plurality of the such bamboo mats being assembled and integrated under pressure and temperatures into a substitute for natural wood having strength, appearance, density and durability similar to natural wood and which products can be produced as large panels of desired thickness or as wooden planks or as beams of varying cross section with smooth faces.|
PATENT APPLICATION FOR:
A NEW TECHNONOLGY TO CONVERT BAMBOO INTO A SUBSTITUTE FOR NATURAL TIMBER
The present invention relates to a novel method of reconstituting bamboo into a product with characteristics similar to naturally grown timber. The Supreme Court banned the indiscriminate felling of trees in the N.E.States until further orders. Consequently, much of the plywood industry based on raw materials from that'region were shut down. The purpose of the ban was to protect the valuable forest cover and preserve the environment.
Wood has been traditionally used the world over for construction of housing, furniture and a variety of other products commonly used by the public. This has resulted in the indiscriminate felling of trees in forests, resulting in a serious environmental catastrophe. The situation was partly overcome by substituting natural timber products with artificially produced composite materials such as particle boards, block boards etc. However, although such products consume less natural timber, it still results in the degradation of forest cover because such products are based on natural timber for raw materials, Trees take many years to grow and therefore, unless the forest cover is adequately protected, regeneration of the forest cover becomes difficult or impossible.
Bamboo grows In large quantities in many parts of the world. It has a short growth period and apart from the natural bamboo forests which can supply huge quantities of the material, it can be grown scientifically on wasteland and result in significantly higher yields per hectare than what occurs in natural forests. There are numerous other advantages gained by growing bamboo in otherwise hostile surroundings.
Present technology for conversion of bamboo into panels of various kinds are expensive and do not produce a material equivalent to natural timber. A process to convert bamboo into a product that can substitute for natural timber in most cases will therefore be of great value. This is particularly relevant \f the bamboo can be utilised with negligible loss in the conversion process.
Summary of Invention:
Traditionally, bamboo is split longitudinally through one wall thickness and flattened out. To facilitate such flattening, small incisions are made across each node after knocking off the external nodes level with the skin. Several such incisions are made along the circumference of the node.
While flattening the bamboo, the internal nodes are also progressively removed to the level of the internal skin. However, the node root material remains adhered to the inner skin.
As a result of the incisions and flattening operation, the wall of the bamboo strip so produced develops cracks and crevices along the length of the culm. No further processing is however done and the strips are used as is for various purposes.
Objects of the Invention:
Accordingly, it is the object of this invention to offer a simple, cost effective process for converting strips of bamboo into a product which is comparable to naturally grown wood.
Limitations in the size of wood substitute produced by the process will only be governed by the size and capacity of the equipment utilised for the purpose.
It is also the object of this invention to specify a process by means of which the cracks and crevices in the bamboo, caused by splitting and flattening, are eliminated and the split strip converted to a homogenous material hereinafter referred to as a layer.
It is further the object of this invention to specify a method by means of which the edges of the layer as specified above are sized to result in making the'edges of the layer straight and parallel.
It is also the object of this invention to specify a method by means of which individual layers produced as above with straight and parallel edges are integrated into a continuous mat which will not tear and be sufficiently rigid to be handled through the further stages of processing without separation or damage.
Most importantly, it is an object of this invention that by result of adoption of this process a plurality of bamboo mats produced as above can be assembled and integrated under temperature and pressure into material which is a substitute for natural wood and has similar properties of strength, appearance and durability: a product which can be produced in the form of large panels of the desired thickness or in the form of the wooden planks and beams of varying cross sections.
Finally, it is an object of this invention that as a result of adoption of this process, an acceptable substitute for natural wood can be produced entirely from bamboo at an economical and attractive cost.
Detailed Description of the Invention:
This invention Is based on the utilisation of the green skin and middle layer strips of the peeled bamboo to produce a material which is an acceptable substitute for natural timber.
The peeled strips of bamboo have longitudinal cracks, resulting from the flattening operation.
It is essential that such gaps and cracks are closed to produce a uniform product. The present method of doing so is to fill the gaps with a filler material which is pressed into the gaps. This is not satisfactory and results in a dies-uniform internal structure. Further, such a method of using a filler material to fills gaps and voids is unsuitable when thin panels like plywood are being manufactured and results in weak boards.
These deficiencies are overcome by the adoption of the new technology which is covered in this patent application:
Closing the gaps and cracks in the material.
This Is done by placing the strip in the assembly fixture (Drawing 1) and applying pressure on the face of the strip by means of hold down pads marked as HDP. While it is held flat, side pressure is applied by a bar marked SPB to close the gaps and cracks In the strip.
To prevent the gaps from opening up again when the material is released from the fixture, cross strips of thin bamboo slivers are glued across the strip at regular intervals by the use of a quick setting glue. Pressure fingers marked as PF are used to hold the cross strips firmly against the material until the glue has set.
The strip is removed from the fixture for further processing. This operation of preventing reopening of the cracks and gaps is an important feature of this invention.
When the material is removed from the fixture, the edges of the strip will not be straight and parallel, but will have some variations.
The second step is to pass the strip between two parallel cutters revolving at high speed (Drawing No 2) so that the edges of the strip are trimmed to become straight and parallel. Adjustable guides Gl and GZ are used to guide the material between the cutters. Hold down rollers, marked as HDR, press the strip down while it is being trimmed.
After trimming, the material Is now classified as a bamboo layer. These preparatory steps to convert the strip into a bamboo layer are very important and crucial to this invention as such layers ensure a finished product which can substitute for natural timber.
Two systems of assembling the layers are envisaged in this invention:
The layers of bamboo prepared as detailed in Steps 1 and 2 are impregnated with a suitable bonding resin by dipping the material into the resin solution . Thereafter the impregnated layers are dried to reduce the moisture content to the desired level.
Impregnated and dried strips are placed in a heated mould (Drawing 3) which has internal dimensions equal to the dimensions of the finished wooden sections desired to be produced. A punch marked P is
pressed down into the mould to compress the layers at the required pressure and temperature. The material is kept under heat and pressure until the resin has set and a complete bonding of the layers has been achieved.
Thereafter it Is removed from the mould. The density of the bamboo wood so produced can be controlled - from the density of a soft wood to the density of a hard wood - by regulating the pressure applied on the Punch P.
The four surfaces of the product ABCD (Drawing 4) will be smooth and have accurate dimensions, eliminating need for further machining. This process is used for manufacture of bamboo wood.
The second method is used for converting prepared bamboo layers into mats.
Individual layers are placed parallel in an assembly fixture (Drawing 5) after application of a suitable quick setting bonding resin to the longitudinal edges of the prepared layers. The layers are held flat by hold down pads marked HDP and side pressure is applied by means of the side pressure bar marked SPB. The assembly is held in position until the resin has set, resulting in a strong bond between the layers, to form what will be termed a bamboo mat.
Such mats can be made either with the middle layers or with the skin layers.
A plurality of such prepared mats are then stacked on metallic cawls to achieve the desired thickness of the finished panel (Drawing 6). Care is taken while stacking the mats one above the other, to ensure that the joints between the layers in each mat are staggered with
respect to such joints in succeeding layers, Green skin mats should onlybc used as face mats and not placed inside the stack.
The mats may also be assembled on the cowls, with mats angularly displaced with respect to adjacent layers, creating a criss-cross potter (Drawing 7).
The cawl with mats is then placed in a Press (Drawing 8) and compressed under heat and pressure, to result in the complete bonding of the mats, to form a uniform products with homogenous internal structure and strength characteristics equal to or exceeding that of conventional boards of the same thickness.
As m bamboo wood production, the density of the panels can be controlled by regulating the pressure applied on the mats, when they are consolidated into a panel:
The essence of the invention is: The products of bamboo panels and bamboo wood having characteristics similar to natural wood, made by converting them from layers of bamboo and a process for manufactumg homogenous bamboo panels/bamboo wood of required dimensions from bamboo layer, in a simple cost effective manner by eliminating cracks and crevices caused by splitting and flattening, so as to have homogeneous layers of bamboo, the edges of the layers to be sized so as to render the edges straight and parallel, which layers are integrated into a continuous rigid mat, the plurality of the such bamboo mats being assembled and integrated under pressure and temperatures into a substitute for natural wood having strength, appearance, density and durability similar to natural wood and which products can be produced as large panels of desired thickness or as wooden planks or as beams of varying cross section with smooth faces.
The invention is described hereinbelow with reference to the accompanying drawings as under:-
Enumeration of Drawings attached wi1+i descriptions: 1. Assembly Fixture for preparing peeled strips
HDP - Hold Down Pads,
SPB - Side Pressure Application Bar
PF - Pressure Fingers
PI - Pressure application Cylinder
P2 - Pressure application Cylinder
P3 - Pressure application cylinder
A - Bamboo layer
B - Cross bonding sliver
FBS - Fixed Back stop
2. Parallel cutters to Trim Edges of Layer
Cl&CZ - Cutter Blades
61 & 62 - Adjustable Guides
HDR - Hold Down Rollers
3. Heated Mould for Bamboo Wood
M - Mould of Required Internal Dimensions
P - Pressure Punch BP - Base Plate
4. Smooth surfaces of manufactured product
5. Assembly Fixture for Mat production HDP - Hold Down Pads
SPB - Side Pressure Bar
BOP - Base Plate
PI - Pressure Application Cylinder
?Z - Pressure Application Cylinder
6. Stacking Mats on Cowls for Pressing, with Layers running parallel to one
El & £2 Cowls
7. Mats stakced with Alternate Layers not parallel, but placed with
8. Pressing Assembled Cawls
HT - Heated Top Patten
HB - Healed Bottom Pkttten
Pressure Application cylinder
1. A Process for manufacturing of Bamboo layers of required dimensions, from peeled bamboo strip of green skin and middle layer of bamboo, longitudinal cracks resulting from flattening operation whereof are closed by placing the strips in the assembly fixture and applying pressure by means of Hold Down Pads (HDP), Side Pressure Bars (SPB), Cross Strips of thin bamboo slivers being glued across the strips at regular intervals by means of quick setting glue, the Pressure Fingers (PF) being used to hold the strips firmly for the glue to set against the material; the strip thus removed from the fixture being passed through two parallel cutters (CI, C2) revolving at high speed, adjustable guides ((51 and 62) guiding the material between the cutters, Hold Down Roller (HDR) pressing the strip down, the edge of the strip thus trimmed to become straight and parallel bamboo layers.
2. A process by which bamboo layers prepared as claimed in claim (1) are impregnated with suitable bonding resm, dried to reduce moisture, placed in a heated mould of desired wooden dimension, punch (P) pressing down into the mould for compression at the required pressure and temperature, the material remaining under heat and pressure whereby bamboo wood having smooth surfaces and accurate dimensions are produced.
3. A process by which bamboo layers prepared as claimed in claim (1) are placed parallel in an assembly fixture subsequent to application of quick setting bond resin to longitudinal edges and are held flat by Hold Down Pads (HDP) and by use of Side Pressure Bars (SPB); the resultant bamboo mats, plurality of which, are stacked on to metallic caw Is to achieve desired thickness of finished panels, the cawl with mats whereupon are placed in a press and compressed under heat and pressure, to convert bamboo layers into bamboo mats.
4. A process as claimed in claim (3) wherein green skin mats are only being used as face mats and are not to be placed inside the stack.
5. A process as cbimed in claim (3 and 4) wherein the mats assembled arc angularly displaced with respect to adjacent layers creating criss-cross patterns.
6. A process as claimed in claim (3) wherein the mats can be made with the
7. A process as claimed in claim (3) wherein the mats can be made with the
8. A process as cbimed in Cbim (3) where the stacking of mats is aone carefully to ensure that joints between layers are staggered.
9. A process as claimed in claim (1 and 2) wherein bamboo layers are impregnated by dipping the layers into suitable bonding solution.
10. A process as claimed in claim (1 and 2) wherein the impregnated bamboo layers are dried to reduce the moisture content to the desired level.
11. A product of bamboo wood as claimed in the process at Cbim (2).
12. A product of bamboo mat/panels as prepared from the process as claimed in cbim (3).
13. A product of Bamboo Wood substantially as described hereinbefore with reference to complete specifications and accompanying drawings.
14. A product of Bamboo Panel/Mat substantially as described hereinbefore with reference to complete specifications and accompanying drawings.
15. A process of production of Bamboo Wood substantially as described in hereinbefore with reference to complete specifications and accompanying drawings.
16. A process of production of Bamboo Panels/Mats substantially as descried hereinbefore with reference to complete specifications and accompanying drawings.
|Indian Patent Application Number||774/MAS/2002|
|PG Journal Number||23/2006|
|Date of Filing||21-Oct-2002|
|Name of Patentee||S.V. KRISHNAMURTY|
|Applicant Address||FLAT 003, SAVOY, 3 COLES ROAD, FRASER TOWN, BANGALORE 560 005|
|PCT International Classification Number||B27J7/00|
|PCT International Application Number||N/A|
|PCT International Filing date|