Engineered bamboo furniture with mortise and tenon joints
Engineered bamboo furniture having components joined with mortise and tenon joints is made by fabricating the components of engineered bamboo, forming corresponding pairs of complementary mortise and tenon joints on the components, and assembling the parts into a finished article of furniture by bonding the respective tenons of the components in the corresponding mortises of the components with an adhesive. The engineered bamboo material is made by treating elongated flat strips of bamboo with high temperature steaming and drying, carbonizing, dehydrating and starch-removal processes, and then laminating the strips to each other using an adhesive under high pressure to form structural sheets or panels of different types, e.g., face-bonded sheets and/or edge-bonded sheets, which can be laminated to each other to form board-like and plywood-like structures. The mortise and tenon joints on the components may be square, trapezoidal, circular, elliptical, or arcuate trapezoids.
This application is a continuation of International App. No. PCT/CN2005/000390, filed Mar. 28, 2005, and having a priority date of Jan. 20, 2005, the entire disclosure of which is incorporated herein by reference.
BACKGROUND1. Technical Field
The present invention relates to furniture making, and in particular, to making engineered bamboo furniture joined with mortise and tenon joints.
2. Related Art
At present, there is a scarcity of timber resources in the world, and the immoderate cutting of trees in previous decades has resulted in an ecological imbalance in the world's forests. Trees are not only expensive to plant, but also require a relatively long time (about 15-50 years) to mature into a size useful for lumber. By contrast, China and other Asian countries have an abundance of bamboo resources. Bamboo is relatively easy and inexpensive to cultivate and takes only a relatively short time (about 5-8 years) to mature to a useful size. Using bamboo instead of conventional wood timber to manufacture furniture can thus reduce the cost of furniture, make full use of the bamboo resource, protect the environment and thereby benefit mankind.
The mortise-and-tenon (“M&T”) method of timber joining has been used in the Chinese culture since ancient times, and thus, the application of the M&T connection structure to bamboo furniture serves to preserve and carry forward an aspect of Chinese culture. “Engineered bamboo” (i.e., manmade bamboo timber, lumber, boards and plywood) is a relatively new material, and to date, has been used only to manufacture bamboo flooring and engineered bamboo panel furniture joined with conventional metal fasteners, e.g., screws. However, there is no record of implementation of M&T connection structures in the manufacture of engineered bamboo furniture.
SUMMARY OF THE INVENTIONIn accordance with the present invention, a new, efficient and environmentally friendly material is provided, viz., engineered bamboo (including bamboo lumber and plywood sheets) that is useful for the manufacture of strong, decorative, high quality furniture in which the parts and components of the furniture are connected with mortise and tenon (“M&T”) joints, without the use of any conventional wood products or joining techniques.
An exemplary method by which the engineered bamboo furniture with M&T joints described in the present invention is manufactured comprises manufacturing component parts of the furniture out of engineered bamboo; forming mortises and tenons of various types and shapes on or in the component parts, and bonding the component parts into a finished article of furniture using the mortises and tenons and an adhesive. The finished furniture may comprise a table, a chair, a cabinet, a bed, a book shelf or the like.
In the method of the present invention, the engineered bamboo material is made by laminating long flat strips of bamboo together with an adhesive under a relatively high pressure. Prior to their lamination, the bamboo strips are treated by heat-digesting, drying at a high temperature, carbonizing, dehydrating and a starch-extraction process. In one possible “face-bonded” embodiment, the processed bamboo strips are then laminated to each other by depositing an adhesive on opposite wide faces of the strips, arranging the strips in a layer with their wide faces in opposition with each other, and pressing them together in a press until the adhesive cures. In this procedure, “blue bamboo” strips, i.e., strips taken from the outer peripheral layer of the bamboo stalk, or “culm,” are laminated alternately with “yellow bamboo” strips, i.e., those taken from the middle or inner wall layers of the bamboo culm, with their respective longitudinal cellulose fibers arranged parallel to each other, to form thin panel structures.
In another, “edge-bonded” embodiment, the opposite narrow edges of the treated bamboo strips are laminated to each other to form thin, single-ply sheets, and a plurality of the sheets are then laminated on top of each other to form plywood-like panels. In one variation of this embodiment, three of the edge-bonded sheets are laminated to each other with their respective longitudinal fibers all extending in the same direction, and with the hard, tough outer skin of blue bamboo strips forming the upper and the lower surfaces of the resulting bamboo panel. In a second variation of this embodiment, the upper and lower sheets of blue bamboo strips are disposed with their longitudinal fibers extending in one direction, and the middle sheet is arranged with the longitudinal fibers of its bamboo strips disposed perpendicular to those of the upper and the lower sheets.
Yet another possible embodiment of the engineered bamboo material comprises an “I-type” lamination, in which three or more layers are laminated together to form a plywood-like panel. The basic form of this embodiment comprises three layers, viz., a face-bonded middle layer, as above, sandwiched between upper and lower edge-bonded layers, as above. In a “multi-I” extension of this method and material, panels of almost any thickness desired are produced by laminating together additional layers in the foregoing alternating arrangement. As above, the longitudinal fibers of the respective alternating edge-bonded and face-bonded layers can be arranged either parallel or perpendicular to one another to achieve different material strength and stiffness properties, and the uppermost and lowermost edge-bonded layers can comprise blue bamboo strips with their hard, dense outer skins facing outward.
In general, the face-bonding and edge-bonding techniques are used to form thin board-like materials, the I-type technique is used to form medium thickness boards and small rectangular panels, and the multi-I method is used to form thick boards and large rectangular panels.
In accordance with the present invention, the tenons and complementary mortises used to join the furniture components can be square, trapezoidal, circular, elliptical, or arcuate trapezoids, and with suitable modification to accommodate the unique properties of engineered bamboo, many conventional mortise and tenon joints can be used for that purpose.
The following are among the many advantages attendant to the methods and materials of the present invention:
1. The engineered bamboo material has superior physical mechanics performance and technical properties over conventional wood timber. It has a high density (≧0.79 g/cm3), bending strength (90 MPa), and rigidity (60 MPa, up to 32 HB, whereas, Zelkova timber is 23 HB and Oak timber is only 24 HB). It also has excellent shock resistance (≧95 kj/m2), and a higher compression strength than either Zelkova or Oak timber.
2. In addition to the above advantages over conventional timber, engineered bamboo also has other outstanding performance advantages, e.g., a lower wet expansion ratio and a lower drying shrinkage (≦0.5%), which enable the design and manufacture of furniture that breaks with the ordinary limitations imposed by the deformations experienced by conventional timber as a result of wet expansion.
3. With suitable modifications, most conventional timber M&T connection techniques can also be used with engineered bamboo assemblies.
4. By improving on the size and fit tolerances of conventional M&T connection techniques, engineered bamboo enables the fabrication of furniture with high accuracy and large, attractive surfaces having a good, smooth finish.
5. Circular or ring-shaped parts or components can be formed simply by bending the bamboo board under either hot or cold pressure, rather than by cutting the lumber into segments and then reassembling them into the desired configuration, which is the method commonly utilized in manufacturing conventional timber furniture. This improvement results in a substantial saving of scrap material.
6. Due to the high density, rigidity and excellent bending and compression strength of engineered bamboo, furniture having the same mechanical properties as larger, thicker conventional wood furniture can be made from thinner but stronger engineered bamboo materials. In this way, natural resources are conserved.
7. Furniture made from bamboo evokes a clean, fresh, cool feeling during the summer-time.
8. The length, width and thickness of the engineered bamboo boards and panels can be determined by the size of the furniture to be made from it. Thus the utilization efficiency of the material can be greatly improved, so that this renewable natural resource is fully utilized.
A better understanding of the above and many other features and advantages of the apparatus of the present invention and the methods of its use may be obtained from a consideration of the detailed description of the exemplary embodiments thereof below, particularly if such consideration is made in conjunction with the appended drawings, wherein like reference numerals are used to identify like elements illustrated in one or more of the figures thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
As described below in conjunction with the accompanying drawings, the present invention provides methods for making high quality engineered bamboo furniture in which the components are joined together with mortise and tenon (“M&T”) joints. Preparation for implementing the methods of the present invention includes following steps:
1. Measuring the mechanical and physical properties (including compression strength, bending strength, flexural modulus, impact hardness, shear strength, rigidity, bending resistance, wear rate, nail holding power, and the like) of the engineered bamboo materials (i.e., the bamboo boards and plywood) to be utilized in the furniture.
2. Determining the desired structural and material (i.e., face-bonded, edge-bonded, or combinations thereof) properties of the furniture components, based on the above mechanical and physical properties of the engineered bamboo materials, and determining the dimensions of the material components necessary to achieve those properties.
3. Determining the optimum M&T joining techniques to be used to join the components of the furniture together, including definition of corresponding product quality standard procedures, processing equipment, cutting tool, die clamp requirements and the like.
The engineered bamboo furniture with M&T joints of the present invention makes use of a manmade, “engineered bamboo” material that is made of elongated, flat bamboo strips having opposite wide faces and opposite narrow edges that are laminated together with an adhesive under high pressure. Prior to their lamination, the bamboo strips are treated by high temperature steaming, high temperature drying, carbonizing, dehydrating and a process that extracts the starch from them. The bamboo strips are cut axially from the bamboo stalk, or “culm,” and comprise two types, viz., “blue bamboo” strips, i.e., those taken from the outer peripheral wall layer of the culm, which have a relatively tough, dense, outer skin, and in which the long, axial, cellulose “veins,” or fibers are more dense, and “yellow bamboo” strips, i.e., those taken from the middle and inner wall layers of the bamboo culm, in which the axial fibers are less dense.
As illustrated in
A “multi-I” extension of the embodiment of
As will be evident from the foregoing description, it is possible to form a wide variety of engineered bamboo material types, including boards, lumber and structural panels, that are useful for making furniture. Generally speaking, the face-bonding and edge-bonding techniques are useful to make thin, board-like materials, the I-type technique is useful to make medium thickness boards and small rectangular panels, and the multi-I method is useful to make thick boards and large rectangular panels.
In accordance with the present invention, the components of the furniture made from the engineered bamboo materials described above (i.e., engineered bamboo boards and panels) are preferably joined together with M&T joints, by the following method: Forming tenons and corresponding mortises (or grooves) of different shapes on or in the engineered bamboo parts; coating the tenon and/or corresponding mortise with an adhesive and inserting the tenon into the corresponding mortise; curing the adhesive; and, finishing the assembled parts. The M&T joining step may include forming butt joints, lap joints, tongue-and-groove joints, dado joints, dowelled joints and dove-tailed joints. The M&T joints utilized may include both open, or through joints, blind or closed joints, and joints that are mitered.
The timber normally used for making furniture comprises a woody, fibrovascular tissue that comes from the trunks of perennial coniferous or broadleaf trees. The diameter of the trunks of such trees depends on the age of the tree. Their wood tends to be elastic, high in wet expansion ratio and drying shrinkage, and is therefore relatively easy to process. Accordingly, conventional wood structures, including furniture, can utilize mortise and tenon joints of many types. However, engineered bamboo has a relatively higher rigidity and strength, and relatively lower wet expansion and drying shrinkage ratios. Accordingly, it is necessary to modify most conventional timber mortise and tenon joints and to implement new M&T joint designs for use with engineered bamboo materials.
Firstly, square tenons 136 and corresponding square mortises 138 are formed at opposite, mitered ends of pair of horizontal foot rails 140 and two pairs of upright leg rails 142, and each of the foot rails is joined to an associated pair of the leg rails to form a pair of leg subassemblies 132.
Secondly, the table top subassembly 134 is formed by joining the mitered ends of four elongated side rails 144 and 146 to each other to define a rectangular frame, as described above in connection with
Lastly, the two leg subassemblies 132 are joined to the table top subassembly 134 with the corresponding M&T joint pairs 136 and 138 on the two subassemblies, by which the table is complete, except for surface finishing procedures.
In the exemplary embodiment of
It may be noted in the above exemplary embodiment that conventional metal hook-and-latch pins 148 and 150 are used to connect the side rails 146 to the headboard 142 and footboard 144 of the bed frame 140. Metal couplings are preferred in this particular application because bed frames must occasionally be disassembled for moving, storage or the like, and accordingly, a permanent adhesive joint is contraindicated.
By now, those of skill in this art will appreciate that many modifications, substitutions and variations can be made in and to the materials, apparatus, configurations and methods of the present invention without departing from its spirit and scope. Accordingly, the scope of the present invention should not be limited to that of the particular embodiments illustrated and described herein, as they are merely exemplary in nature, but rather, should be fully commensurate with that of the claims appended hereafter and their functional equivalents.
Claims
1. A method for making engineered bamboo furniture joined together with mortise and tenon joints, the method comprising:
- making furniture components of engineered bamboo;
- forming corresponding pairs of complementary mortise and tenon joints on the components; and,
- assembling the components into a finished article of furniture by bonding the respective tenons of the components in the corresponding mortises of the components with an adhesive.
2. An article of furniture made in accordance with the method of claim 1.
3. The method of claim 1, wherein the article of furniture comprises a table, a chair, a cabinet, a bed or a shelf.
4. The method of claim 1, wherein making furniture components comprises:
- providing flat, elongated strips of bamboo, each strip having a pair of opposite wide faces and a pair of opposite narrow edges;
- treating the strips by high temperature steaming, high temperature drying, carbonizing, dehydrating and starch removal processes; and,
- laminating the strips together with an adhesive under high pressure.
5. The method of claim 4, wherein laminating the bamboo strips together comprises:
- depositing an adhesive on the opposite wide faces of the strips;
- arranging the strips in a layer such that their respective wide faces are disposed in opposition to each other and respective longitudinal fibers of the strips are disposed parallel to each other and,
- adhering the respective opposing wide faces of the strips to each other to form a face-bonded sheet.
6. The method of claim 4, wherein laminating the bamboo strips together comprises:
- depositing an adhesive on the opposite narrow edges of the strips;
- arranging the strips in a layer such that their respective narrow edges are disposed in opposition to each other and respective longitudinal fibers of the strips are disposed parallel to each other and,
- adhering the opposing narrow edges of the strips to each other to form an edge-bonded sheet.
7. The method of claim 6, further comprising laminating a plurality of the edge-bonded sheets together to form a panel.
8. The method of claim 7, wherein the respective longitudinal fibers of the bamboo strips of each sheet are disposed parallel to the respective longitudinal fibers of the bamboo strips of adjacent sheets.
9. The method of claim 7, wherein the respective longitudinal fibers of the bamboo strips of each sheet are disposed perpendicular to the respective longitudinal fibers of the bamboo strips of adjacent sheets.
10. A method for making engineered bamboo furniture components, the method comprising:
- providing flat, elongated strips of bamboo, each strip having longitudinal fibers, a pair of opposite wide faces and a pair of opposite narrow edges;
- treating the strips by high temperature steaming, high temperature drying, carbonizing, dehydrating and starch removal processes;
- depositing an adhesive on the opposite wide faces of a first group of the strips;
- arranging the first group of strips in a layer such that their respective wide faces are disposed in opposition to each other and their respective longitudinal fibers are disposed parallel to each other;
- adhering the respective opposing wide faces of the first group of strips to each other to form a face-bonded sheet;
- depositing an adhesive on the opposite narrow edges of a second group of the strips;
- arranging the second group of strips in a layer such that their narrow edges are disposed in opposition to each other and their respective longitudinal fibers are disposed parallel to each other;
- adhering the respective opposing narrow edges of the strips of the second group of strips to each other to form an edge-bonded sheet; and,
- laminating the face-bonded sheet between two edge-bonded sheets to form an I-type panel.
11. The method of claim 10, wherein the respective longitudinal fibers of the bamboo strips of the face-bonded sheet are disposed parallel to the respective longitudinal fibers of the bamboo strips of the edge-bonded sheets.
12. The method of claim 10, wherein the respective longitudinal fibers of the bamboo strips of the face-bonded sheet are disposed perpendicular to the respective longitudinal fibers of the bamboo strips of the edge-bonded sheets.
13. The method of claim 10, further comprising laminating a plurality of the face-bonded and edge-bonded sheets together in an alternating order.
14. The method of claim 10, wherein each of the edge-bonded sheets comprises blue bamboo strips, each having an outer skin facing outward from the I-type panel.
15. The method of claim 1, wherein the corresponding pairs of complementary mortise and tenon joints on the components are square, trapezoidal, circular, elliptical, or arcuate trapezoids.
16. An article of furniture, comprising:
- a first component made of engineered bamboo and having a tenon formed thereon;
- a second component made of engineered bamboo and having a mortise complementary to the tenon of the first component formed therein; and,
- means for adhering the tenon of the first component in the mortise of the second component.
17. The article of claim 16, wherein at least one of the first and second components comprises:
- a plurality of flat, elongated strips of bamboo, each having a pair of opposite wide faces,
- the strips being arranged in a layer such that their respective wide faces are disposed in opposition to each other and respective longitudinal fibers of the strips are disposed parallel to each other; and,
- an adhesive disposed on the opposite wide faces of the strips and adhering the respective opposing wide faces of the strips to each other to form a face-bonded sheet.
18. The article of claim 16, wherein at least one of the first and second components comprises:
- a plurality of flat, elongated strips of bamboo, each having a pair of opposite narrow edges,
- the strips being arranged in a layer such that their respective narrow edges are disposed in opposition to each other and respective longitudinal fibers of the strips are disposed parallel to each other; and,
- an adhesive disposed on the opposite narrow edges of the strips and adhering the opposing narrow edges of the strips to each other to form an edge-bonded sheet.
19. The article of claim 16, wherein at least one of the first and second components comprises:
- a first plurality of flat, elongated bamboo strips, each having longitudinal fibers and a pair of opposite wide faces and arranged in a layer such that their respective wide faces are disposed in opposition to each other and their respective longitudinal fibers are disposed parallel to each other;
- an adhesive disposed on the opposite wide faces of the first plurality of strips and adhering the respective opposing wide faces of the strips to each other to form a face-bonded sheet;
- a second plurality of flat, elongated bamboo strips, each having longitudinal fibers and a pair of opposite narrow edges and being arranged in a layer such that their respective narrow edges are disposed in opposition to each other and their respective longitudinal fibers are disposed parallel to each other;
- an adhesive disposed on the opposite narrow edges of the second plurality of strips and adhering the opposing narrow edges of the strips to each other to form an edge-bonded sheet; and,
- an adhesive laminating the face-bonded sheet to the edge-bonded sheet.
20. The article of claim 19, wherein at least one of the first and second components comprises a plurality of the face-bonded sheets laminated to a plurality of the edge-bonded sheets in an alternating order.
Type: Application
Filed: Jun 2, 2006
Publication Date: Sep 28, 2006
Inventor: Maria Yee (Scotts Valley, CA)
Application Number: 11/445,843
International Classification: A47C 1/12 (20060101);