CA2100131A1 - Method and apparatus for making pressed articles from wood - Google Patents
Method and apparatus for making pressed articles from woodInfo
- Publication number
- CA2100131A1 CA2100131A1 CA 2100131 CA2100131A CA2100131A1 CA 2100131 A1 CA2100131 A1 CA 2100131A1 CA 2100131 CA2100131 CA 2100131 CA 2100131 A CA2100131 A CA 2100131A CA 2100131 A1 CA2100131 A1 CA 2100131A1
- Authority
- CA
- Canada
- Prior art keywords
- work piece
- wood
- conditioning
- heat
- pressing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27M—WORKING OF WOOD NOT PROVIDED FOR IN SUBCLASSES B27B - B27L; MANUFACTURE OF SPECIFIC WOODEN ARTICLES
- B27M3/00—Manufacture or reconditioning of specific semi-finished or finished articles
- B27M3/0013—Manufacture or reconditioning of specific semi-finished or finished articles of composite or compound articles
- B27M3/0026—Manufacture or reconditioning of specific semi-finished or finished articles of composite or compound articles characterised by oblong elements connected laterally
- B27M3/0053—Manufacture or reconditioning of specific semi-finished or finished articles of composite or compound articles characterised by oblong elements connected laterally using glue
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27M—WORKING OF WOOD NOT PROVIDED FOR IN SUBCLASSES B27B - B27L; MANUFACTURE OF SPECIFIC WOODEN ARTICLES
- B27M1/00—Working of wood not provided for in subclasses B27B - B27L, e.g. by stretching
- B27M1/02—Working of wood not provided for in subclasses B27B - B27L, e.g. by stretching by compressing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27M—WORKING OF WOOD NOT PROVIDED FOR IN SUBCLASSES B27B - B27L; MANUFACTURE OF SPECIFIC WOODEN ARTICLES
- B27M3/00—Manufacture or reconditioning of specific semi-finished or finished articles
- B27M3/0093—Manufacture or reconditioning of specific semi-finished or finished articles of raised panels, i.e. panels having a profiled surface
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Forests & Forestry (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Chemical And Physical Treatments For Wood And The Like (AREA)
Abstract
ABSTRACT OF THE INVENTION
This invention relates to a novel method and an apparatus which are useful for making formed articles from wood. The method involves conditioning the wood by plasticization prior to pressing and while the work piece is substantially uniform in cross section.
Conditioning is followed by pressing the heated wood between forming dies to impress the desired form into the product. The conditioning and pressing stages are done in two steps involving apparatus that has separate conditioning and pressing parts. In another embodiment of the present invention the apparatus performs the conditioning and pressing stages within a single working chamber.
This invention relates to a novel method and an apparatus which are useful for making formed articles from wood. The method involves conditioning the wood by plasticization prior to pressing and while the work piece is substantially uniform in cross section.
Conditioning is followed by pressing the heated wood between forming dies to impress the desired form into the product. The conditioning and pressing stages are done in two steps involving apparatus that has separate conditioning and pressing parts. In another embodiment of the present invention the apparatus performs the conditioning and pressing stages within a single working chamber.
Description
2~0~31 METHOD AND APPARATUS FOR NAgING
PRESSED ARTI~LES FRCM WOOD
This invention relates to a method and apparatus for making formed articles from wood. The method involves conditioning the wood by plasticization prior to pressing and while the work piece is substantially uniform in cross section. Conditioning is followed by pressing the heated wood between forming dies to impress the desired form into the product. The conditioning and pressing stages are done in two steps involving apparatus that has separate conditioning and pressing parts. In another embodiment of the present invention the apparatus performs the conditioning and pressing stages within a single working chamber.
Forming of wood by pressing requires the wood matrix to be in a softened state. In dry, unheated state wood is relatively brittle and difficult to mold. When exposed to combination of moisture and temperature wood acquires a varying degree of plasticity. It undergoes transition from a glassy to a soft state. The temperature at which wood softens is called the glass transition temperature and is a function of moisture content.
, Wood has three major structural components. Cellulose and hemicellulose form the ~ibre that gives wood its strength. Lignin is a thermoplastic polymer that binds the wood matrix together. All three constituents of woody cells are subject to softening when exposed to temperature and moisture. However, their glass transitions are different. For lignin it varies from about 160C
when dry to about 100C when saturated. Hemicellulose, on the other hand, softens at about 180C in dry state and at about 50C in saturated condition. Cellulose crystallites do not show softening until about 200C and their glass transition does not depend on th~
2 ~
!'~ moisture content because of their hydrophobic nature. The amorphous : .
~5 regions of the elementary fibrils, however, are likely plasticized by moisture. The glass transition characteristics of the amorphous cellulose is assumed to be similar to that of hemicellulose.
?
Forming action deflects the wood matrix from its natural configuration. To preserve the new shape requires the wood constituents to deflect and to flow into the new shape. It also requires that the wood matrix is subsequently "locked" in the new configuration. Plasticized wood flows easily and upon cooling the ~ new shape is preserved.
¦ Large compression of non-plasticized wood can result in serious damage to its structure. Partially softened wood can also sustain damage as the higher loads are supported by the constituents which have not been softened. This may lead to development of fissures, thus weakening or destroying the wood.
Non-uniformity of heating of compressed wood can be detrimental to i the product. If cold wood is subjected to full forming pressures 20 before heating, as is the case in the typical manufacturing process for wood composites, a portion of the compression energy is stored in the cold mat in the form of potential energy ~elastic and delayed elastic strain). Some of this energy is released when the subsequent heating changes the elastic characteristics of some parts of the wood matrix. A nonuniform heating lowers the stiffness of the heated areas and this allows some of the stored energy to be relaxed by compressing the softened fibres. Consequently, the areas that are receiving preferential heating will be subjected to a larger amount of compression. This may result in development of cracks and wood cell collapse. Most heating processes produce large temperatures gradients during heating.
For successful shaping of wood, as in wood bending, deep embossing or forming, the entire work piece and all the constituents of wood should be in adequately plastic state prior to pressing. In bending of solid wood the softening is usually accomplished by steaming the work piece in a pressure vessel for a period of time before the bending procedure. Plasticization needed for deep embossing or forming composite products or large sizes of wood is not as easily achieved on practical basis. A typical steam treatment of larger cross sections requires prolonged heating times. Steaming in a pressure vessel would be difficult to apply to wood compositions containing typical wood binding glues.
Majority of manufacturing methods used for wood composite products involve simultaneous application of rapid heating and forming pressure. A rapid and uniform heating of the work piece can be achieved by high frequency or steam injection heating methods.
However, these heating methods are difficult to apply to non-flat contoured surfaces. High frequency heating would be highly nonuniform and the steam injection would be inefficient due to steam leaks. In present processes the high frequency and steam injection heating is limited to products with planar surfaces which are in contact with the heat applicators. The existing art which applies high frequency for heating is described by Fraser et al., US Patent No. 3,888,715 and Lamberts et al., US Patent No.
4,221,950. The disclosed methods are suitable for the manufacture of flat panel prod~cts. The requirement of a substantially planar interface between the applicator of high frequency or steam injection heating and the surface of the heated wood limits the applicability of these efficient heating methods.
The present invention discloses an improved method and apparatus which allows an efficient use of high frequency or steam 2~ Q ~
injection heating methods to plasticize the work piece prior to forming. In the present method the wood is plasticized and formed in two separate steps. The apparatus of the present invention achieves a high degree of wood plasticity in one step and presses the softened wood into a shape by a pair of pressing dies in a second step. Although this invention is applicable to manufacture of shaped wood products it can be used to produced flat panel products which can be densi~ied to a high degree.
;0 This invention pertains to a method of making pressed products from wood in an apparatus having a working space defined by a conditioning part and a forming part, the method comprising the steps of: a) preparing a moisture containing formable work piece;
b) positioning the formable work piece in the conditioning part of the apparatus comprising an upper and a lower pressure and heat applicators, within the conditioning part subjecting the work piece simultaneously to a restraining external pressure and heat and heating the restrained work piece to the boiling point of the moisture within the said article, the restraining external pressure opposing the internally generated steam pressure, the moisture and heat plasticizing the work piece; c) transferring the work piece to the forming part of the apparatus comprising àn upper and a lower forming die assemblies; d) compressing the plasticized work piece between the forming die assemblies to impress the desired shape into the plasticized work piece.
This invention further pertains to a two stage method of making pressed wood composite product, the method having a conditioning stage and a forming stage, the method comprising the steps of: a) preparing a composite assembly constructed of a plurality of wood elements and a wood bondiny glue between the elements, the glue between the wood elements forming a plurality of ~luelines within the composite assembly; b) transferring the composite assembly into an apparatus having a conditioning part and a forming part, first positioning the composite assembly in the conditioning part of the apparatus comprising an upper and a lower pressure and heat applicators assemblies; c) in the conditioning part of the apparatus simultaneously subjecting the wood composite to a restraining pressure and heat and heating the wood composite assembly to the boiling temperature of the moisture within the said composite assembly, the restraining external pressure opposing the internal steam pressure within the assembly wherein the internal steam pressure in excess of the opposing restraining external pressure being allowed to vent to the exterior of the wood composite assembly, the elevated temperature and moisture within the wood composite assembly plasticizing the wood; d) transferring the plasticized wood composite assembly from the conditioning part to the forming part of the apparatus, the forming part comprising an upper and a lower pressing die assemblies movable in respect to each other; e) compressing the plasticized wood composite assembly between the pressing die assemblies to impress the desired shape ~0 into the conditioned wood composite assembly.
`The working space of the apparatus can be pressurized during the transfer of the conditioned wood article or composite assembly by air or by steam. Conditioning of the wood article or composite assembly can be performed by high frequency heating method or by steam injection heating method. The boiling temperature of the moisture in the conditioning step can be between about 100C and about 150C and the restraining pressure in the conditioning step can be between zero and about 100 psi. Pressing dies can be heated or can be cooled within the forming part of the apparatus.
This invention further pertains to an apparatus for making 21~0131 pressed articles from wood, the apparatus comprising: a) conditioning part further comprising upper and lower frame means supporting mutually opposing upper and lower heat applicators, the heat applicators being disposed to apply restraining pressure to a work piece inserted therebetween, the opposing pressing surfaces of the said applicators being substantially planar and defining a conditioning chamber, the distance between the opposing planar pressing surfaces defining the opening of the conditioning chamber;
means for varying the opening of the conditioning chamber; means for holding the work piece elevated above the lower heat applicator whereby creating a gap between the work piece and the planar pressing surface of the lower heat applicator; b) forming part comprising upper and lower pressing frame means, the upper pressing frame means supporting an upper pressing die, the lower pressing frame means supporting a lower pressing die, the upper pressing die being attached to the upper pressing frame means, the lower pressing die not being attached to the lower pressing frame means and being movable and transferable between the forming part and the conditioning part of the apparatus, said lower pressing die being slidable into the gap between the elevated work piece and the lower heat applicator; c) means for depositing the work piece on the forming surface of the lower pressing die while the said pressing die is in the conditioning chamber and located below the work piece; d) moving means for transfer of the lower pressing die between the conditioning part and the pressing part of the apparatus; e) means for removing of the pressed work piece from the forming part.
The heat applicators in the conditioning part of the apparatus according to the present invention can be high frequency heat applicators or can be steam injection heat applicators. Holding of the elevated work piece in the conditioning part to facilitate its 2~01~1 transfer by the movable lower pressing die can be done by mechanical means by engaging the edges of the wood article or composite assembly, or can be done by vacuum applied at the interface between the planar surface of the upper heat applicator and the wood article. The apparatus can be internally pressurized by air or steam pressure at least during the transfer of the wood article between the conditioning and forming parts.
This invention further pertains to an apparatus for making pressed articles from wood comprising: working chamber defined by upper and lower heat applicators spaced apart to provide therebetween a working opening, the said heat applicators having substantially planar heating surfaces disposed to apply pressure and heat to a work piece within the working opening of the chamber, the improvement comprising means for elevating the work piece above the lower heat applicator and retaining the said work piece in elevated position above the lower heat applicator thereby generating a gap between the work piece and the planar heating surface of the lower heat applicator, further comprising means for inserting a lower pressing die into the said gap between the work piece and the lower heat applicator and lowering the work piece onto the inserted lower pressing die, means for inserting an upper pressing die into a space between the work piece and the upper heat applicator, means for applying pressure to the work piece therebetween the said pressing dies, means for sliding the upper and lower dies in and out of the conditioning and pressing chamber.
The substance and nature of this invention in certain embodiments is illustrated in the follow~ng drawings. The drawings should not be interpreted as restricting the spirit or scope of the invention in any way:
21001~1 Figure 1 is a schematic cross sectional view of an apparatus according to the first embodiment of the present invention in the conditioning phase of operation Figure 2 is a schematic cross sectional view of an apparatus according to the first embodiment of the present invention in the transfer phase of the operation.
Figure 3 is a schematic cross sectional view of an apparatus according to the first embodiment of the present invention in the forming phase of the operation.
Figure 4 is a schematic cross sectional view of an apparatus according to the second embodiment of the present invention.
The method according to the present invention involves plasticization of a wood work piece followed by forming of the plasticized wood by pressure between a pair of forming dies. High degree of plasticization is achieved by heating the wood work piece while restrained by pressure of between zero and about 100 psi to temperature of between about 100C and about 150C. The heating methods suitable for practising the present invention should provide a uniform and fast heating of the entire work piece. It should allow an efficient heat transfer to the work piece or heat ~eneration within the work piece while the work piece is under restraining pressure that is generally lower than the pressure needed to form the final product.
Efficient and rapid heating methods, which also provide uniform heat distribution and can be used to heat wood work piece under lower restraining pressure, are the high frequency and steam injection heating methods. However, both of these methods work well only with substantially planar interface between the respective heat applicators and the wood work piece. This is easily achievable in manufacturing of flat panel products. In processes involving 210~31 forming, such as in deep embossing, a simultaneous heating and forming using high frequency, steam injection or sometimes a conventional hot press heating methods is difficult or impossible to apply because the pressing dies are by definition not planar. A
non-planar interface between the heat applicators and the wood work piece prevents adequate heat transfer, induces various fringing fields and does not allow steam pressure development due to an unsealed interface. The result is a less efficient and more nonuniform heating.
' The above described difficulty in applying an efficient, uniform and rapid heating in manufacturing o~ pressed wood products is overcome by the present method. The improved method allows separation of heating and forming. It also achieves high degree of plasticization prior to forming which results in improvement of the product's quality and improved forming process.
The method comprises two separate, but coupled steps. In the first step the wood work piece is conditioned in a heating ~O apparatus. The heating can be by high frequency heating device or it can be by a steam injection heating device. Such devices are widely available in the industry. The heat applicators of these devices can be made in pairs and placed so they mutually oppose each other as in upper and lower positions and are movable in respect to each other to close or open the gap between them. The wood work piece is placed between the heat applicators and subjected to a small restraining pressure between the heat applicators of about zero to about 100 psi. In most situations the external pressure applied during conditioning will be between about ~0 5 psi and about 20 psi.
As explained previously, wood is plasticized by both moisture and heat. To adequately plasticize the entire wood matrix, all components of wood cell should be fully plasticized. Depending on the moisture content of the wood, lignin, hemicellulose and cellulose soften at different temperatures. To achieve softening of all components at the typical production moisture contents of between 5% and 25%, the conditioning temperature should be selected between about 100C and about 150C. The preferred conditioning temperature range is between about 120~C and about 140C. At these temperatures the moisture within the wood work piece will be at the boiling point for at least a portion of the heating time. The steam within the wood structure will be at an elevated pressure. The external restraining pressure can be used to control the boiling point and the evaporation rate of the moisture within the wood work piece. The control is based on the well known relationship between saturated steam pressure and temperature. This controlling feature is especially useful when the wood work piece is a composite assembly comprising wood elèments with thermosetting glue dispersed between the elements. By selecting the proper external restraining pressure to act on the work piece will establish a specific boiling temperature. Thus, the external restraining pressure is controlling the boiling point and the plasticizing temperature of the heated wood. A substantially planar interface between the heat applicators and the wood work piece is important in the conditioning process also to maintain an adequate control of the plasticization temperature and the moisture evaporation rate. Control of the conditioning process may be designed to prevent cure of the glue ~ystem that may be used as a component of the work piece. A number of glue systems, such as the common phenol formaldehyde glues, allow heating to the preferred conditioning temperature without curing, providing the moisture evaporation is controlled. Limited strength of the glueline is, however, desirable during the transfer of the work piece. Therefore, at the end of the conditioning phase, -210013~
~he restraining pressure can be temporarily increased to consolidate the work piece.
~ n the second step the conditioned and plasticized wood work piece can be transferred to a forming apparatus comprising a pair of forming dies, or the pressing dies can be inserted into the conditioning device. The upper and lower forming dies have the desired shape and apply the required pressure to form the wood. The dies can be heated in order to transfer additional heat into the pressed wood or to prevent heat loss during the pressing period if it is so re~uired. With certain products it may be beneficial to cool the product immediately after the form is achieved. In this case the quenching can be achieved by cooling the pressing dies or the entire pressing apparatus. It should be obvious that this method allows any combination of heating and cooling of the pressed product within the forming apparatus and any such combination is considered within the scope of this invention.
'~
At certain conditioning temperatures the internal steam 2~ pressures may be higher than the internal strength of the heated wood work piece. A possible steam pressure damage could result after the release of the external restraining pressure at the completion of the conditioning step. This problem can be overcome in practising the present invention by providing the apparatus with a sealing means which can pressure seal the conditioning and forming apparatus such, that the conditioning and forming steps are performed within the pressure-tight working space of the said apparatus. The working space of the apparatus can be pressuri~ed by air or other gas before releasing the external restraining pressure. The pressure within the working space can be such as to balance the internal steam pressure within the restrained wood work piece. It may be possible to select the air or gas pressure within the sealed working space at a lower value than the internal steam pressure such that the resulting differential pressure is less than the critical damage causing pressure. Any suitable sealing method can be used to provide the required sealing of the working space.
Figure 1 shows schematically a cross section of a two chamber heating and pressing apparatus according to the present invention comprising a conditioning part 10 and a forming part 11. The heat applicators indicated as 14 and 15 in the conditioning part 10 can be heating electrodes for high frequency heating, sometimes designated as a radio frequency heater. Other high frequency heating method which can be used to practise the present invention is the industrial microwave heating method. In addition to high frequency heating the apparatus can incorporate steam injection heating method or other conventional heating methods.
The conditioning part 10 comprises an upper frame means 12 which can be nonmovably supported and a movable lower frame means 13. The upper heat applicator 14 and the lower heat applicator 15 are shown as high frequency heating electrodes incorporated in the frame means 12 and 13. The electrodes are preferably electrically isolated from~ the main body of the conditioning part 10 by isolating means 16 and 17. However, in practising the present invention the isolating means 14 and 15 can be omitted. Electrical connections are provided b~ connectors 18 and 19 which are, in turn, connected to a source of high frequency energy. The wood work piece 21 is shown located within the conditioning part 10 between the electrodes 14 and 15. The frame means 12 incorporates vacuum ports 20 through which vacuum can be drawn within the common interface between the heat applicator 1~, isolating means 16 and the wood work piece 21. A suitable ~eans for feeding the wood work piece 21 into the conditioning part is not shown but any known i 21~0131 method can be incorporated.
The forming part 11 is shown in juxtaposition with theconditioning part 10. It comprises an upper pressing frame means 22 which can be nonmovably supported and a movable lower pressing frame means 23. Pressing die 24 is shown nonmovably supported by the upper pressing frame means 22. The lower pressing die 25 is movably supported by the lower pressing frame means 23. The support of the pressing die 25 is such that it can slide on the surface of the pressing frame means 23 between the conditioning part 10 and the forming part 11, when the lower frames of the conditioning part and the forming part are suitably aligned. Channels 26 can be used to heat or cool the upper and lower pressing frame means 22 and 23.
.
PRESSED ARTI~LES FRCM WOOD
This invention relates to a method and apparatus for making formed articles from wood. The method involves conditioning the wood by plasticization prior to pressing and while the work piece is substantially uniform in cross section. Conditioning is followed by pressing the heated wood between forming dies to impress the desired form into the product. The conditioning and pressing stages are done in two steps involving apparatus that has separate conditioning and pressing parts. In another embodiment of the present invention the apparatus performs the conditioning and pressing stages within a single working chamber.
Forming of wood by pressing requires the wood matrix to be in a softened state. In dry, unheated state wood is relatively brittle and difficult to mold. When exposed to combination of moisture and temperature wood acquires a varying degree of plasticity. It undergoes transition from a glassy to a soft state. The temperature at which wood softens is called the glass transition temperature and is a function of moisture content.
, Wood has three major structural components. Cellulose and hemicellulose form the ~ibre that gives wood its strength. Lignin is a thermoplastic polymer that binds the wood matrix together. All three constituents of woody cells are subject to softening when exposed to temperature and moisture. However, their glass transitions are different. For lignin it varies from about 160C
when dry to about 100C when saturated. Hemicellulose, on the other hand, softens at about 180C in dry state and at about 50C in saturated condition. Cellulose crystallites do not show softening until about 200C and their glass transition does not depend on th~
2 ~
!'~ moisture content because of their hydrophobic nature. The amorphous : .
~5 regions of the elementary fibrils, however, are likely plasticized by moisture. The glass transition characteristics of the amorphous cellulose is assumed to be similar to that of hemicellulose.
?
Forming action deflects the wood matrix from its natural configuration. To preserve the new shape requires the wood constituents to deflect and to flow into the new shape. It also requires that the wood matrix is subsequently "locked" in the new configuration. Plasticized wood flows easily and upon cooling the ~ new shape is preserved.
¦ Large compression of non-plasticized wood can result in serious damage to its structure. Partially softened wood can also sustain damage as the higher loads are supported by the constituents which have not been softened. This may lead to development of fissures, thus weakening or destroying the wood.
Non-uniformity of heating of compressed wood can be detrimental to i the product. If cold wood is subjected to full forming pressures 20 before heating, as is the case in the typical manufacturing process for wood composites, a portion of the compression energy is stored in the cold mat in the form of potential energy ~elastic and delayed elastic strain). Some of this energy is released when the subsequent heating changes the elastic characteristics of some parts of the wood matrix. A nonuniform heating lowers the stiffness of the heated areas and this allows some of the stored energy to be relaxed by compressing the softened fibres. Consequently, the areas that are receiving preferential heating will be subjected to a larger amount of compression. This may result in development of cracks and wood cell collapse. Most heating processes produce large temperatures gradients during heating.
For successful shaping of wood, as in wood bending, deep embossing or forming, the entire work piece and all the constituents of wood should be in adequately plastic state prior to pressing. In bending of solid wood the softening is usually accomplished by steaming the work piece in a pressure vessel for a period of time before the bending procedure. Plasticization needed for deep embossing or forming composite products or large sizes of wood is not as easily achieved on practical basis. A typical steam treatment of larger cross sections requires prolonged heating times. Steaming in a pressure vessel would be difficult to apply to wood compositions containing typical wood binding glues.
Majority of manufacturing methods used for wood composite products involve simultaneous application of rapid heating and forming pressure. A rapid and uniform heating of the work piece can be achieved by high frequency or steam injection heating methods.
However, these heating methods are difficult to apply to non-flat contoured surfaces. High frequency heating would be highly nonuniform and the steam injection would be inefficient due to steam leaks. In present processes the high frequency and steam injection heating is limited to products with planar surfaces which are in contact with the heat applicators. The existing art which applies high frequency for heating is described by Fraser et al., US Patent No. 3,888,715 and Lamberts et al., US Patent No.
4,221,950. The disclosed methods are suitable for the manufacture of flat panel prod~cts. The requirement of a substantially planar interface between the applicator of high frequency or steam injection heating and the surface of the heated wood limits the applicability of these efficient heating methods.
The present invention discloses an improved method and apparatus which allows an efficient use of high frequency or steam 2~ Q ~
injection heating methods to plasticize the work piece prior to forming. In the present method the wood is plasticized and formed in two separate steps. The apparatus of the present invention achieves a high degree of wood plasticity in one step and presses the softened wood into a shape by a pair of pressing dies in a second step. Although this invention is applicable to manufacture of shaped wood products it can be used to produced flat panel products which can be densi~ied to a high degree.
;0 This invention pertains to a method of making pressed products from wood in an apparatus having a working space defined by a conditioning part and a forming part, the method comprising the steps of: a) preparing a moisture containing formable work piece;
b) positioning the formable work piece in the conditioning part of the apparatus comprising an upper and a lower pressure and heat applicators, within the conditioning part subjecting the work piece simultaneously to a restraining external pressure and heat and heating the restrained work piece to the boiling point of the moisture within the said article, the restraining external pressure opposing the internally generated steam pressure, the moisture and heat plasticizing the work piece; c) transferring the work piece to the forming part of the apparatus comprising àn upper and a lower forming die assemblies; d) compressing the plasticized work piece between the forming die assemblies to impress the desired shape into the plasticized work piece.
This invention further pertains to a two stage method of making pressed wood composite product, the method having a conditioning stage and a forming stage, the method comprising the steps of: a) preparing a composite assembly constructed of a plurality of wood elements and a wood bondiny glue between the elements, the glue between the wood elements forming a plurality of ~luelines within the composite assembly; b) transferring the composite assembly into an apparatus having a conditioning part and a forming part, first positioning the composite assembly in the conditioning part of the apparatus comprising an upper and a lower pressure and heat applicators assemblies; c) in the conditioning part of the apparatus simultaneously subjecting the wood composite to a restraining pressure and heat and heating the wood composite assembly to the boiling temperature of the moisture within the said composite assembly, the restraining external pressure opposing the internal steam pressure within the assembly wherein the internal steam pressure in excess of the opposing restraining external pressure being allowed to vent to the exterior of the wood composite assembly, the elevated temperature and moisture within the wood composite assembly plasticizing the wood; d) transferring the plasticized wood composite assembly from the conditioning part to the forming part of the apparatus, the forming part comprising an upper and a lower pressing die assemblies movable in respect to each other; e) compressing the plasticized wood composite assembly between the pressing die assemblies to impress the desired shape ~0 into the conditioned wood composite assembly.
`The working space of the apparatus can be pressurized during the transfer of the conditioned wood article or composite assembly by air or by steam. Conditioning of the wood article or composite assembly can be performed by high frequency heating method or by steam injection heating method. The boiling temperature of the moisture in the conditioning step can be between about 100C and about 150C and the restraining pressure in the conditioning step can be between zero and about 100 psi. Pressing dies can be heated or can be cooled within the forming part of the apparatus.
This invention further pertains to an apparatus for making 21~0131 pressed articles from wood, the apparatus comprising: a) conditioning part further comprising upper and lower frame means supporting mutually opposing upper and lower heat applicators, the heat applicators being disposed to apply restraining pressure to a work piece inserted therebetween, the opposing pressing surfaces of the said applicators being substantially planar and defining a conditioning chamber, the distance between the opposing planar pressing surfaces defining the opening of the conditioning chamber;
means for varying the opening of the conditioning chamber; means for holding the work piece elevated above the lower heat applicator whereby creating a gap between the work piece and the planar pressing surface of the lower heat applicator; b) forming part comprising upper and lower pressing frame means, the upper pressing frame means supporting an upper pressing die, the lower pressing frame means supporting a lower pressing die, the upper pressing die being attached to the upper pressing frame means, the lower pressing die not being attached to the lower pressing frame means and being movable and transferable between the forming part and the conditioning part of the apparatus, said lower pressing die being slidable into the gap between the elevated work piece and the lower heat applicator; c) means for depositing the work piece on the forming surface of the lower pressing die while the said pressing die is in the conditioning chamber and located below the work piece; d) moving means for transfer of the lower pressing die between the conditioning part and the pressing part of the apparatus; e) means for removing of the pressed work piece from the forming part.
The heat applicators in the conditioning part of the apparatus according to the present invention can be high frequency heat applicators or can be steam injection heat applicators. Holding of the elevated work piece in the conditioning part to facilitate its 2~01~1 transfer by the movable lower pressing die can be done by mechanical means by engaging the edges of the wood article or composite assembly, or can be done by vacuum applied at the interface between the planar surface of the upper heat applicator and the wood article. The apparatus can be internally pressurized by air or steam pressure at least during the transfer of the wood article between the conditioning and forming parts.
This invention further pertains to an apparatus for making pressed articles from wood comprising: working chamber defined by upper and lower heat applicators spaced apart to provide therebetween a working opening, the said heat applicators having substantially planar heating surfaces disposed to apply pressure and heat to a work piece within the working opening of the chamber, the improvement comprising means for elevating the work piece above the lower heat applicator and retaining the said work piece in elevated position above the lower heat applicator thereby generating a gap between the work piece and the planar heating surface of the lower heat applicator, further comprising means for inserting a lower pressing die into the said gap between the work piece and the lower heat applicator and lowering the work piece onto the inserted lower pressing die, means for inserting an upper pressing die into a space between the work piece and the upper heat applicator, means for applying pressure to the work piece therebetween the said pressing dies, means for sliding the upper and lower dies in and out of the conditioning and pressing chamber.
The substance and nature of this invention in certain embodiments is illustrated in the follow~ng drawings. The drawings should not be interpreted as restricting the spirit or scope of the invention in any way:
21001~1 Figure 1 is a schematic cross sectional view of an apparatus according to the first embodiment of the present invention in the conditioning phase of operation Figure 2 is a schematic cross sectional view of an apparatus according to the first embodiment of the present invention in the transfer phase of the operation.
Figure 3 is a schematic cross sectional view of an apparatus according to the first embodiment of the present invention in the forming phase of the operation.
Figure 4 is a schematic cross sectional view of an apparatus according to the second embodiment of the present invention.
The method according to the present invention involves plasticization of a wood work piece followed by forming of the plasticized wood by pressure between a pair of forming dies. High degree of plasticization is achieved by heating the wood work piece while restrained by pressure of between zero and about 100 psi to temperature of between about 100C and about 150C. The heating methods suitable for practising the present invention should provide a uniform and fast heating of the entire work piece. It should allow an efficient heat transfer to the work piece or heat ~eneration within the work piece while the work piece is under restraining pressure that is generally lower than the pressure needed to form the final product.
Efficient and rapid heating methods, which also provide uniform heat distribution and can be used to heat wood work piece under lower restraining pressure, are the high frequency and steam injection heating methods. However, both of these methods work well only with substantially planar interface between the respective heat applicators and the wood work piece. This is easily achievable in manufacturing of flat panel products. In processes involving 210~31 forming, such as in deep embossing, a simultaneous heating and forming using high frequency, steam injection or sometimes a conventional hot press heating methods is difficult or impossible to apply because the pressing dies are by definition not planar. A
non-planar interface between the heat applicators and the wood work piece prevents adequate heat transfer, induces various fringing fields and does not allow steam pressure development due to an unsealed interface. The result is a less efficient and more nonuniform heating.
' The above described difficulty in applying an efficient, uniform and rapid heating in manufacturing o~ pressed wood products is overcome by the present method. The improved method allows separation of heating and forming. It also achieves high degree of plasticization prior to forming which results in improvement of the product's quality and improved forming process.
The method comprises two separate, but coupled steps. In the first step the wood work piece is conditioned in a heating ~O apparatus. The heating can be by high frequency heating device or it can be by a steam injection heating device. Such devices are widely available in the industry. The heat applicators of these devices can be made in pairs and placed so they mutually oppose each other as in upper and lower positions and are movable in respect to each other to close or open the gap between them. The wood work piece is placed between the heat applicators and subjected to a small restraining pressure between the heat applicators of about zero to about 100 psi. In most situations the external pressure applied during conditioning will be between about ~0 5 psi and about 20 psi.
As explained previously, wood is plasticized by both moisture and heat. To adequately plasticize the entire wood matrix, all components of wood cell should be fully plasticized. Depending on the moisture content of the wood, lignin, hemicellulose and cellulose soften at different temperatures. To achieve softening of all components at the typical production moisture contents of between 5% and 25%, the conditioning temperature should be selected between about 100C and about 150C. The preferred conditioning temperature range is between about 120~C and about 140C. At these temperatures the moisture within the wood work piece will be at the boiling point for at least a portion of the heating time. The steam within the wood structure will be at an elevated pressure. The external restraining pressure can be used to control the boiling point and the evaporation rate of the moisture within the wood work piece. The control is based on the well known relationship between saturated steam pressure and temperature. This controlling feature is especially useful when the wood work piece is a composite assembly comprising wood elèments with thermosetting glue dispersed between the elements. By selecting the proper external restraining pressure to act on the work piece will establish a specific boiling temperature. Thus, the external restraining pressure is controlling the boiling point and the plasticizing temperature of the heated wood. A substantially planar interface between the heat applicators and the wood work piece is important in the conditioning process also to maintain an adequate control of the plasticization temperature and the moisture evaporation rate. Control of the conditioning process may be designed to prevent cure of the glue ~ystem that may be used as a component of the work piece. A number of glue systems, such as the common phenol formaldehyde glues, allow heating to the preferred conditioning temperature without curing, providing the moisture evaporation is controlled. Limited strength of the glueline is, however, desirable during the transfer of the work piece. Therefore, at the end of the conditioning phase, -210013~
~he restraining pressure can be temporarily increased to consolidate the work piece.
~ n the second step the conditioned and plasticized wood work piece can be transferred to a forming apparatus comprising a pair of forming dies, or the pressing dies can be inserted into the conditioning device. The upper and lower forming dies have the desired shape and apply the required pressure to form the wood. The dies can be heated in order to transfer additional heat into the pressed wood or to prevent heat loss during the pressing period if it is so re~uired. With certain products it may be beneficial to cool the product immediately after the form is achieved. In this case the quenching can be achieved by cooling the pressing dies or the entire pressing apparatus. It should be obvious that this method allows any combination of heating and cooling of the pressed product within the forming apparatus and any such combination is considered within the scope of this invention.
'~
At certain conditioning temperatures the internal steam 2~ pressures may be higher than the internal strength of the heated wood work piece. A possible steam pressure damage could result after the release of the external restraining pressure at the completion of the conditioning step. This problem can be overcome in practising the present invention by providing the apparatus with a sealing means which can pressure seal the conditioning and forming apparatus such, that the conditioning and forming steps are performed within the pressure-tight working space of the said apparatus. The working space of the apparatus can be pressuri~ed by air or other gas before releasing the external restraining pressure. The pressure within the working space can be such as to balance the internal steam pressure within the restrained wood work piece. It may be possible to select the air or gas pressure within the sealed working space at a lower value than the internal steam pressure such that the resulting differential pressure is less than the critical damage causing pressure. Any suitable sealing method can be used to provide the required sealing of the working space.
Figure 1 shows schematically a cross section of a two chamber heating and pressing apparatus according to the present invention comprising a conditioning part 10 and a forming part 11. The heat applicators indicated as 14 and 15 in the conditioning part 10 can be heating electrodes for high frequency heating, sometimes designated as a radio frequency heater. Other high frequency heating method which can be used to practise the present invention is the industrial microwave heating method. In addition to high frequency heating the apparatus can incorporate steam injection heating method or other conventional heating methods.
The conditioning part 10 comprises an upper frame means 12 which can be nonmovably supported and a movable lower frame means 13. The upper heat applicator 14 and the lower heat applicator 15 are shown as high frequency heating electrodes incorporated in the frame means 12 and 13. The electrodes are preferably electrically isolated from~ the main body of the conditioning part 10 by isolating means 16 and 17. However, in practising the present invention the isolating means 14 and 15 can be omitted. Electrical connections are provided b~ connectors 18 and 19 which are, in turn, connected to a source of high frequency energy. The wood work piece 21 is shown located within the conditioning part 10 between the electrodes 14 and 15. The frame means 12 incorporates vacuum ports 20 through which vacuum can be drawn within the common interface between the heat applicator 1~, isolating means 16 and the wood work piece 21. A suitable ~eans for feeding the wood work piece 21 into the conditioning part is not shown but any known i 21~0131 method can be incorporated.
The forming part 11 is shown in juxtaposition with theconditioning part 10. It comprises an upper pressing frame means 22 which can be nonmovably supported and a movable lower pressing frame means 23. Pressing die 24 is shown nonmovably supported by the upper pressing frame means 22. The lower pressing die 25 is movably supported by the lower pressing frame means 23. The support of the pressing die 25 is such that it can slide on the surface of the pressing frame means 23 between the conditioning part 10 and the forming part 11, when the lower frames of the conditioning part and the forming part are suitably aligned. Channels 26 can be used to heat or cool the upper and lower pressing frame means 22 and 23.
.
3 operation of the preferred embodiment of the apparatus j according to the present invention is depicted sequentially in ~ Figures 1, 2 and 3. Figure 1 shows schematically the conditioning ! phase of the manufacturing cycle. The wood work piece is restrained ¦ by a low external pressure between the upper heat applicator 14 and 20 the lower heat applicator 15. rhe isolating means 16 and 17 may form a part of the pressing surface if the wood work piece is larger than the pressing area of the heat applicators 14 and 15.
Heat is supplied to the wood work piece 21 until the desired plasticizing conditions within the work piece are achieved.
Additional pressure may be applied to the conditioned work piece 21 to further consolidate it, and at about the same time vacuum is applied within the interface between the heat applicator 14 and the work piece 21 by means of ports 20. If the work piece is a wood composite assembly, the glueline should be sufficiently formed at ~0 this stage to retain the work piece as one piece without an external restraint. Next, the lower frame means is lowered to open the gap between the upper and lower frame means. The vacuum above 2~ 001~1 the work piece should be sufficient to hold it in contact with the heat applicator 14 as the applicator 1~ is being lowered along with the frame means 13. Mechanical means can also be used to retain the work piece 21 in position so it is not lowered when it is no longer supported by the lower heat applicator 15.
Figure 2 depicts the phase in the operating sequence when the work piece 21 is held by vacuum in the elevated position and the resulting gap between the work piece 21 and the lower heat applicator 15 is sufficient to allow insertion of the lower pressing die 25. When the lower pressing die is inserted between the work piece and the lower heat applicator 15, the vacuum can be released and the work piece allowed to rest on the lower pressing die. The working openings of both conditioning and forming parts can be sealed from the exterior of the apparatus by any suitable sealing means to form a common cavity which can be pressurized. The pressurization can be done by air and the air pressure would counteract the internal steam pressure within the wood work piece.
In the following step the movable lower pressing die 25 is moved into the pressing position within the forming part, as indicated in Figure 1. The wood work piece is transported with the lower pressing die while it remains located on the s`aid pressing die.
Figure 3 shows a cross section of the apparatus according to the present invention with the wood work piece 21 located in the pressing location within the forming part 11. The conditioned and plasticized work piece is compressed between the pair of upper and lower pressing dies 24 and 25 and is formed into the desired shape.
The pressed wood work piece can be further heated by heat transferred from the heated pressing frame means 22 and 23. The additional heat can be applied to further stabilize the wood product. An alternative treatment of the pressed wood work piece 21 210013~ ~
is cooling by dissipating the heat from the work piece in~o cold pressing frame means 22 and 23. Heating or cooling of the pressing frame means can be achieved by supplying heating or cooling medium through channels 26.
Figure 4 illustrates another embodiment of the present invention which comprises a press 28 and a pair of upper and lower pressing dies 33 and 34 both movable into and out of the press 28.
The press 28 comprises upper frame means 29 and lower frame means 30, the upper frame means supporting an upper heat applicator 31 and the lower frame means supporting a lower heat applicator 32.
The work piece 21 is conditioned as described in relation to Figure 1. The conditioned work piece is retained in elevated position in the working opening of the apparatus by means of vacuum or other means to allow the lower pressing die 33 to be inserted into the gap between the work piece 21 and the lower heat applicator 32.
With the lower pressing die in location within the press, the work piece is lowered onto the lower pressing die 34 by releasing the vacuum or any other means which may be used to hold the work piece in the elevated position. The lower frame means 30 is subsequently lowered to provide a gap between the upper heat applicator 31 and the work piece 21 into which the upper moving pressing die 33 can be inserted. When the upper and lower moving pressing dies 33 and 34 are in place the lower frame means applies forming pressure to the work piece between the upper and lower pressing dies. The press 28 can be suitably sealed and pressurized to balance the internal steam pressure within the work piece.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.
~0 ~:
',
Heat is supplied to the wood work piece 21 until the desired plasticizing conditions within the work piece are achieved.
Additional pressure may be applied to the conditioned work piece 21 to further consolidate it, and at about the same time vacuum is applied within the interface between the heat applicator 14 and the work piece 21 by means of ports 20. If the work piece is a wood composite assembly, the glueline should be sufficiently formed at ~0 this stage to retain the work piece as one piece without an external restraint. Next, the lower frame means is lowered to open the gap between the upper and lower frame means. The vacuum above 2~ 001~1 the work piece should be sufficient to hold it in contact with the heat applicator 14 as the applicator 1~ is being lowered along with the frame means 13. Mechanical means can also be used to retain the work piece 21 in position so it is not lowered when it is no longer supported by the lower heat applicator 15.
Figure 2 depicts the phase in the operating sequence when the work piece 21 is held by vacuum in the elevated position and the resulting gap between the work piece 21 and the lower heat applicator 15 is sufficient to allow insertion of the lower pressing die 25. When the lower pressing die is inserted between the work piece and the lower heat applicator 15, the vacuum can be released and the work piece allowed to rest on the lower pressing die. The working openings of both conditioning and forming parts can be sealed from the exterior of the apparatus by any suitable sealing means to form a common cavity which can be pressurized. The pressurization can be done by air and the air pressure would counteract the internal steam pressure within the wood work piece.
In the following step the movable lower pressing die 25 is moved into the pressing position within the forming part, as indicated in Figure 1. The wood work piece is transported with the lower pressing die while it remains located on the s`aid pressing die.
Figure 3 shows a cross section of the apparatus according to the present invention with the wood work piece 21 located in the pressing location within the forming part 11. The conditioned and plasticized work piece is compressed between the pair of upper and lower pressing dies 24 and 25 and is formed into the desired shape.
The pressed wood work piece can be further heated by heat transferred from the heated pressing frame means 22 and 23. The additional heat can be applied to further stabilize the wood product. An alternative treatment of the pressed wood work piece 21 210013~ ~
is cooling by dissipating the heat from the work piece in~o cold pressing frame means 22 and 23. Heating or cooling of the pressing frame means can be achieved by supplying heating or cooling medium through channels 26.
Figure 4 illustrates another embodiment of the present invention which comprises a press 28 and a pair of upper and lower pressing dies 33 and 34 both movable into and out of the press 28.
The press 28 comprises upper frame means 29 and lower frame means 30, the upper frame means supporting an upper heat applicator 31 and the lower frame means supporting a lower heat applicator 32.
The work piece 21 is conditioned as described in relation to Figure 1. The conditioned work piece is retained in elevated position in the working opening of the apparatus by means of vacuum or other means to allow the lower pressing die 33 to be inserted into the gap between the work piece 21 and the lower heat applicator 32.
With the lower pressing die in location within the press, the work piece is lowered onto the lower pressing die 34 by releasing the vacuum or any other means which may be used to hold the work piece in the elevated position. The lower frame means 30 is subsequently lowered to provide a gap between the upper heat applicator 31 and the work piece 21 into which the upper moving pressing die 33 can be inserted. When the upper and lower moving pressing dies 33 and 34 are in place the lower frame means applies forming pressure to the work piece between the upper and lower pressing dies. The press 28 can be suitably sealed and pressurized to balance the internal steam pressure within the work piece.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.
~0 ~:
',
Claims (17)
1. A method of making pressed products from wood in an apparatus having a working space defined by a conditioning part and a forming part, the method comprising the steps of:
a) preparing a moisture containing formable work piece;
b) positioning the formable work piece in the conditioning part of the apparatus comprising an upper and a lower pressure and heat applicators, within the conditioning part subjecting the work piece simultaneously to a restraining external pressure and heat and heating the restrained work piece to the boiling point of the moisture within the said article, the restraining external pressure opposing the internally generated steam pressure, the moisture and heat plasticizing the work piece;
c) transferring the work piece to the forming part of the apparatus comprising an upper and a lower forming die assemblies;
d) compressing the plasticized work piece between the forming die assemblies to impress the desired shape into the plasticized work piece.
a) preparing a moisture containing formable work piece;
b) positioning the formable work piece in the conditioning part of the apparatus comprising an upper and a lower pressure and heat applicators, within the conditioning part subjecting the work piece simultaneously to a restraining external pressure and heat and heating the restrained work piece to the boiling point of the moisture within the said article, the restraining external pressure opposing the internally generated steam pressure, the moisture and heat plasticizing the work piece;
c) transferring the work piece to the forming part of the apparatus comprising an upper and a lower forming die assemblies;
d) compressing the plasticized work piece between the forming die assemblies to impress the desired shape into the plasticized work piece.
2. A two stage method of making pressed wood composite product, the method having a conditioning stage and a forming stage, the method comprising the steps of:
a) preparing a composite assembly constructed of a plurality of wood elements and a wood bonding glue between the elements, the glue between the wood elements forming a plurality of gluelines within the composite assembly;
b) transferring the composite assembly into an apparatus having a conditioning part and a forming part, first positioning the composite assembly in the conditioning part of the apparatus - Page 1 of Claims -comprising an upper and a lower pressure and heat applicators assemblies;
c) in the conditioning part of the apparatus simultaneously subjecting the wood composite to a restraining pressure and heat and heating the wood composite assembly to the boiling temperature of the moisture within the said composite assembly, the restraining external pressure opposing the internal steam pressure within the assembly wherein the internal steam pressure in excess of the opposing restraining external pressure being allowed to vent to the exterior of the wood composite assembly, the elevated temperature and moisture within the wood composite assembly plasticizing the wood;
d) transferring the plasticized wood composite assembly from the conditioning part to the forming part of the apparatus, the forming part comprising an upper and a lower pressing die assemblies movable in respect to each other;
e) compressing the plasticized wood composite assembly between the pressing die assemblies to impress the desired shape into the conditioned wood composite assembly.
a) preparing a composite assembly constructed of a plurality of wood elements and a wood bonding glue between the elements, the glue between the wood elements forming a plurality of gluelines within the composite assembly;
b) transferring the composite assembly into an apparatus having a conditioning part and a forming part, first positioning the composite assembly in the conditioning part of the apparatus - Page 1 of Claims -comprising an upper and a lower pressure and heat applicators assemblies;
c) in the conditioning part of the apparatus simultaneously subjecting the wood composite to a restraining pressure and heat and heating the wood composite assembly to the boiling temperature of the moisture within the said composite assembly, the restraining external pressure opposing the internal steam pressure within the assembly wherein the internal steam pressure in excess of the opposing restraining external pressure being allowed to vent to the exterior of the wood composite assembly, the elevated temperature and moisture within the wood composite assembly plasticizing the wood;
d) transferring the plasticized wood composite assembly from the conditioning part to the forming part of the apparatus, the forming part comprising an upper and a lower pressing die assemblies movable in respect to each other;
e) compressing the plasticized wood composite assembly between the pressing die assemblies to impress the desired shape into the conditioned wood composite assembly.
3. The method according to claim 1 wherein the working space of the apparatus is pressurized by air during the transfer of the work piece in step c).
4. The method according to claim 2 wherein the heating in step c) is performed by high frequency heating method.
5. The method according to claim 2 wherein the heating in step c) is performed by steam injection method.
6. The method according to claim 2 wherein the boiling temperature in step c) is between about 100°C to about 150°C.
- Page 2 of Claims -
- Page 2 of Claims -
7. The method according to claim 2 wherein the pressing die assemblies in step e) are heated.
8. The method according to claim 2 wherein the pressing die assemblies in step e) are cooled.
9. The method according to claim 2 wherein the restraining pressure is between zero and about 100 psi.
10. An apparatus for making pressed articles from wood, the apparatus comprising:
a) conditioning part further comprising upper and lower frame means supporting mutually opposing upper and lower heat applicators, the heat applicators being disposed to apply restraining pressure to a work piece inserted therebetween, the opposing pressing surfaces of the said applicators being substantially planar and defining a conditioning chamber, the distance between the opposing planar pressing surfaces defining the opening of the conditioning chamber;
means for varying the opening of the conditioning chamber;
means for holding the work piece elevated above the lower heat applicator whereby creating a gap between the work piece and the planar pressing surface of the lower heat applicator;
b) forming part comprising upper and lower pressing frame means, the upper pressing frame means supporting an upper pressing die, the lower pressing frame means supporting a lower pressing die, the upper pressing die being attached to the upper pressing frame means, the lower pressing die not being attached to the lower pressing frame means and being movable and transferable between the forming part and the conditioning part of the apparatus, said lower pressing die being slidable into the gap between the elevated work piece and the lower - Page 3 of Claims -heat applicator;
c) means for depositing the work piece on the forming surface of the lower pressing die while the said pressing die is in the conditioning chamber and located below the work piece;
d) moving means for transfer of the lower pressing die between the conditioning part and the pressing part of the apparatus;
e) means for removing of the pressed work piece from the forming part.
a) conditioning part further comprising upper and lower frame means supporting mutually opposing upper and lower heat applicators, the heat applicators being disposed to apply restraining pressure to a work piece inserted therebetween, the opposing pressing surfaces of the said applicators being substantially planar and defining a conditioning chamber, the distance between the opposing planar pressing surfaces defining the opening of the conditioning chamber;
means for varying the opening of the conditioning chamber;
means for holding the work piece elevated above the lower heat applicator whereby creating a gap between the work piece and the planar pressing surface of the lower heat applicator;
b) forming part comprising upper and lower pressing frame means, the upper pressing frame means supporting an upper pressing die, the lower pressing frame means supporting a lower pressing die, the upper pressing die being attached to the upper pressing frame means, the lower pressing die not being attached to the lower pressing frame means and being movable and transferable between the forming part and the conditioning part of the apparatus, said lower pressing die being slidable into the gap between the elevated work piece and the lower - Page 3 of Claims -heat applicator;
c) means for depositing the work piece on the forming surface of the lower pressing die while the said pressing die is in the conditioning chamber and located below the work piece;
d) moving means for transfer of the lower pressing die between the conditioning part and the pressing part of the apparatus;
e) means for removing of the pressed work piece from the forming part.
11. The apparatus according to claim 10 wherein the heat applicators in the conditioning part are high frequency heat applicators.
12. The apparatus according to claim 10 wherein the heat applicators in the conditioning part are steam injection heat applicators.
13. The apparatus according to claim 10 wherein holding of the elevated work piece is by way of gripping the edges of the said work piece by a mechanical means.
14. The apparatus according to claim 10 wherein holding of the elevated work piece is achieved by vacuum applied at the interface between the upper planar pressing surface of the upper heat applicator and the work piece.
15. The apparatus according to the claim 10 wherein the said apparatus is internally pressurized at least during the transfer of the work piece between the conditioning and forming parts.
16. The apparatus according to claim 15 wherein the pressure medium is air.
- Page 4 of Claims -
- Page 4 of Claims -
17. An apparatus for making pressed articles from wood comprising:
working chamber defined by upper and lower heat applicators spaced apart to provide therebetween a working opening, the said heat applicators having substantially planar heating surfaces disposed to apply pressure and heat to a work piece located within the working opening of the chamber, the improvement comprising means for elevating the work piece above the lower heat applicator and retaining the said work piece in elevated position above the lower heat applicator thereby generating a gap between the work piece and the planar heating surface of the lower heat applicator, further comprising means for inserting a lower pressing die into the said gap between the work piece and the lower heat applicator and lowering the work piece onto the inserted lower pressing die, means for inserting an upper pressing die into a space between the work piece and the upper heat applicator, means for applying pressure to the work piece therebetween the said pressing dies, means for sliding the upper and lower dies in and out of the conditioning and pressing chamber.
- Page 5 of Claims -
working chamber defined by upper and lower heat applicators spaced apart to provide therebetween a working opening, the said heat applicators having substantially planar heating surfaces disposed to apply pressure and heat to a work piece located within the working opening of the chamber, the improvement comprising means for elevating the work piece above the lower heat applicator and retaining the said work piece in elevated position above the lower heat applicator thereby generating a gap between the work piece and the planar heating surface of the lower heat applicator, further comprising means for inserting a lower pressing die into the said gap between the work piece and the lower heat applicator and lowering the work piece onto the inserted lower pressing die, means for inserting an upper pressing die into a space between the work piece and the upper heat applicator, means for applying pressure to the work piece therebetween the said pressing dies, means for sliding the upper and lower dies in and out of the conditioning and pressing chamber.
- Page 5 of Claims -
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2100131 CA2100131A1 (en) | 1993-07-08 | 1993-07-08 | Method and apparatus for making pressed articles from wood |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2100131 CA2100131A1 (en) | 1993-07-08 | 1993-07-08 | Method and apparatus for making pressed articles from wood |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2100131A1 true CA2100131A1 (en) | 1995-01-09 |
Family
ID=4151906
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2100131 Abandoned CA2100131A1 (en) | 1993-07-08 | 1993-07-08 | Method and apparatus for making pressed articles from wood |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2100131A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006117928A1 (en) * | 2005-04-27 | 2006-11-09 | Olympus Corporation | Compressed wood processing apparatus and method of processing |
| EP2217415A2 (en) * | 2007-11-19 | 2010-08-18 | Padana AG | Method and apparatus for producing figured veneer |
| CZ305267B6 (en) * | 2014-01-08 | 2015-07-08 | Mendelova Univerzita V Brně | Device for producing wood-based boards with enhanced density profile |
| US9610703B2 (en) | 2007-11-19 | 2017-04-04 | Danzer GmbH | Method and apparatus for producing figured veneer |
| US11498240B2 (en) | 2017-12-29 | 2022-11-15 | Ahf, Llc | Densified wood including process for preparation |
-
1993
- 1993-07-08 CA CA 2100131 patent/CA2100131A1/en not_active Abandoned
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006117928A1 (en) * | 2005-04-27 | 2006-11-09 | Olympus Corporation | Compressed wood processing apparatus and method of processing |
| US7395844B2 (en) | 2005-04-27 | 2008-07-08 | Olympus Corporation | Processing apparatus and method of processing |
| EP2217415A2 (en) * | 2007-11-19 | 2010-08-18 | Padana AG | Method and apparatus for producing figured veneer |
| EP2217415A4 (en) * | 2007-11-19 | 2014-02-26 | Padana Ag | Method and apparatus for producing figured veneer |
| US8852483B2 (en) | 2007-11-19 | 2014-10-07 | Padana Ag | Method and apparatus for producing figured veneer |
| US9610703B2 (en) | 2007-11-19 | 2017-04-04 | Danzer GmbH | Method and apparatus for producing figured veneer |
| CZ305267B6 (en) * | 2014-01-08 | 2015-07-08 | Mendelova Univerzita V Brně | Device for producing wood-based boards with enhanced density profile |
| US11498240B2 (en) | 2017-12-29 | 2022-11-15 | Ahf, Llc | Densified wood including process for preparation |
| US11931917B2 (en) | 2017-12-29 | 2024-03-19 | Ahf, Llc | Densified wood including process for preparation |
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