CA2342840A1 - Method and apparatus for manufacturing endless veneer laminates - Google Patents
Method and apparatus for manufacturing endless veneer laminates Download PDFInfo
- Publication number
- CA2342840A1 CA2342840A1 CA002342840A CA2342840A CA2342840A1 CA 2342840 A1 CA2342840 A1 CA 2342840A1 CA 002342840 A CA002342840 A CA 002342840A CA 2342840 A CA2342840 A CA 2342840A CA 2342840 A1 CA2342840 A1 CA 2342840A1
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- Canada
- Prior art keywords
- strand
- veneer
- prepress
- pressure
- continuously operating
- 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
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 25
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000010438 heat treatment Methods 0.000 claims abstract description 45
- 238000003825 pressing Methods 0.000 claims abstract description 25
- 239000002023 wood Substances 0.000 claims abstract description 11
- 239000002245 particle Substances 0.000 claims abstract description 8
- 239000000463 material Substances 0.000 claims abstract description 6
- 239000003292 glue Substances 0.000 claims description 19
- 239000004033 plastic Substances 0.000 claims description 13
- 238000004026 adhesive bonding Methods 0.000 claims description 4
- 235000012773 waffles Nutrition 0.000 claims description 3
- 239000004809 Teflon Substances 0.000 claims description 2
- 229920006362 Teflon® Polymers 0.000 claims description 2
- 229910000831 Steel Inorganic materials 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- 238000010924 continuous production Methods 0.000 description 3
- 210000001331 nose Anatomy 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 229920002522 Wood fibre Polymers 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27D—WORKING VENEER OR PLYWOOD
- B27D3/00—Veneer presses; Press plates; Plywood presses
- B27D3/04—Veneer presses; Press plates; Plywood presses with endless arrangement of moving press plates, belts, or the like
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27D—WORKING VENEER OR PLYWOOD
- B27D1/00—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring
- B27D1/04—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring to produce plywood or articles made therefrom; Plywood sheets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
- B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
- B27N3/08—Moulding or pressing
- B27N3/24—Moulding or pressing characterised by using continuously acting presses having endless belts or chains moved within the compression zone
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
- B30B15/34—Heating or cooling presses or parts thereof
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Wood Science & Technology (AREA)
- Forests & Forestry (AREA)
- Manufacturing & Machinery (AREA)
- Veneer Processing And Manufacture Of Plywood (AREA)
- Dry Formation Of Fiberboard And The Like (AREA)
- Chemical And Physical Treatments For Wood And The Like (AREA)
Abstract
A method and an apparatus for carrying out the process for manufacturing endless veneer laminates from an endless string of veneer panels or for manufacturing OSB, LSL or wafer board from an endless string of spread wood particles, comprising a feeding device for the strand of veneer panels or the strand, an RF or MW
heating device, a prepress and a continuously operating press. The apparatus of the invention consists of the RF or MW heating device having an entry and an exit shielding device and a prepress located downstream from it whose pressing range, including transfer nose or, if applicable, transfer plate, extends almost to the clamping area of the continuously operating press, and the prepress can exercise a pressure of 5 to 30 bar surface pressure or 3 to 20 N/mm linear pressure on the material to be pressed.
heating device, a prepress and a continuously operating press. The apparatus of the invention consists of the RF or MW heating device having an entry and an exit shielding device and a prepress located downstream from it whose pressing range, including transfer nose or, if applicable, transfer plate, extends almost to the clamping area of the continuously operating press, and the prepress can exercise a pressure of 5 to 30 bar surface pressure or 3 to 20 N/mm linear pressure on the material to be pressed.
Description
Method and Apparatus for Manufacturing Endless Veneer Laminates Field of the Invention The present invention relates to the field of veneer laminates, and more specifically, to a method and apparatus for manufacturing endless veneer laminates from a strand of veneer panels.
Background of the Invention A method for manufacturing veneer laminates is known from DE I96 27 024 wherein, after leaving the veneer panel placement station, the strand of veneer panels is prepressed and preheated in a continuously operating prepress with integrated RF or microwave preheating. After leaving the prepress, the strand of veneer panels is transferred to a conveyer belt and transported through the remaining section to the intake point of the main press. In this area, an undesired rising up of the basically wavy veneer panels occurs, thus permitting the glue seams to dry out as well as a loss of valuable energy. When veneer laminates (LVL) are manufactured in a continuous process, during the preheating process temperatures of 65 degrees - 75 degrees are currently used in order to increase the production speed, which reduces the pressing time in the continuously operating press by 50 percent compared to conventional manufacturing processes. Despite this significantly short pressing time that has led to an increase in productivity, the continuously operating facilities for the manufacture of veneer laminates are approximately 30 - 50 percent more expensive than conventional facilities with the same productivity. Moreover, the maximum productivity is limited by the technical feasibility of the press length of the continuously operating press, which is currently approximately 60 m.
In current facilities, the problem is that the preheating temperature cannot be increased any further, since this would result in a procuring or drying of the glue seams before the pressure at the intake point of the press can be built up and before the veneer panels to be manufactured can be pressed to form a veneer laminate. The remaining energy required until the curing temperature of the glue is reached must of necessity be introduced into the product by means of the conventional heating of heating plates and steel belts. Due to the inferior thermal conductivity of wood, an additional temperature increase in the middle of the veneer panel laminate only occurs after a certain delay time, which is necessary for heating the peripheral areas. The subsequent temperature increase only occurs very slowly. Since the veneer laminates are made very thick (30 mm - 150 mm), the pressing process still takes between 10 minutes and 45 minutes.
Summary of the Invention The objective of the invention is a method and apparatus by which a higher quality of veneer laminate can be manufactured in continuous production and by which a greater throughput can be achieved through quicker processing.
In accordance with one aspect of the present invention there is provided a method of manufacturing endless veneer laminates from a strand of veneer panels made of veneer panels in multiple layers superimposed on each other and behind each other and with intermediate layers of glue by means of gluing and pressing in a heated, continuously operating press, said method comprising the following steps: (a) pressing the strand of veneer panels together under light pressure before or during preheating in such a way that the veneer panels lie flat one on top of the other; (b) passing the strand of veneer panels through an RF (radio frequency) or MW (microwave frequency) heating section until the respective curing temperature of the glue is reached or slightly exceeded in the strand; (c) prepressing the heated strand of veneer panels at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press; and (d) pressing the strand of veneer panels in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW heating section until it has reached a desired panel thickness and glue seams have cured.
In accordance with another aspect of the present invention there is provided a method of manufacturing endless OSB, LSL (laminated strand lumber) or wafer panels from a strand of wood particles of long chips or wood waffles, spread in multiple layers superimposed on each other and behind each other, by gluing and pressing in a heated, continuously operating press, said method comprising the steps of: (a) prior to preheating, precompressing the strand under light pressure in such a way that the wood particles lie firmly against or upon each other; (b) while maintaining the precompression thickness passing the strand through an RF or MW heating section until the respective curing temperature of the glue has been reached or slightly exceeded in the strand; (c) prepressing the heated strand at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press; and (d) pressing the partially cured strand in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW heating section until it has reached a desired panel thickness and is cured.
In accordance with yet another aspect of the present invention there is provided an apparatus for carrying out the method according to any one of claims 1 to 5 for manufacturing endless veneer laminates from an endless string of veneer panels or for manufacturing OSB, LSL or wafer board from an endless string of spread wood particles, comprising a feeding device for the strand of veneer panels or the strand, an RF or MW heating device, a prepress and a continuously operating press, the RF
or MW
heating device having an entry and an exit shielding device and that a prepress is located downstream from it whose pressing range, including a transfer nose and a transfer plate, extends almost to the clamping area of the continuously operating press, and that the material to be pressed can be subjected to a pressing pressure of between 5 and 30 bar surface pressure or between 3 and 20 N/mrn linear pressure when passing through the prepress.
More specifically, according to an embodiment of the present invention, a method for the continuous production of LVL panels or veneer laminates lies in the implementation of the following steps:
First, the strand of veneer panels is pressed together before or during preheating in such a way that the veneer panels lie flat one on top of the other. In a second step, the strand of veneer panels passes through an RF or MW heating section until the respective curing temperature of the applied glue is reached or slightly exceeded in the strand.
Following this, the heated strand of veneer panels is prepressed at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press.
Finally, the strand of veneer panels is pressed in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW heating section until it has reached the final panel thickness and the glue seams have cured completely.
Background of the Invention A method for manufacturing veneer laminates is known from DE I96 27 024 wherein, after leaving the veneer panel placement station, the strand of veneer panels is prepressed and preheated in a continuously operating prepress with integrated RF or microwave preheating. After leaving the prepress, the strand of veneer panels is transferred to a conveyer belt and transported through the remaining section to the intake point of the main press. In this area, an undesired rising up of the basically wavy veneer panels occurs, thus permitting the glue seams to dry out as well as a loss of valuable energy. When veneer laminates (LVL) are manufactured in a continuous process, during the preheating process temperatures of 65 degrees - 75 degrees are currently used in order to increase the production speed, which reduces the pressing time in the continuously operating press by 50 percent compared to conventional manufacturing processes. Despite this significantly short pressing time that has led to an increase in productivity, the continuously operating facilities for the manufacture of veneer laminates are approximately 30 - 50 percent more expensive than conventional facilities with the same productivity. Moreover, the maximum productivity is limited by the technical feasibility of the press length of the continuously operating press, which is currently approximately 60 m.
In current facilities, the problem is that the preheating temperature cannot be increased any further, since this would result in a procuring or drying of the glue seams before the pressure at the intake point of the press can be built up and before the veneer panels to be manufactured can be pressed to form a veneer laminate. The remaining energy required until the curing temperature of the glue is reached must of necessity be introduced into the product by means of the conventional heating of heating plates and steel belts. Due to the inferior thermal conductivity of wood, an additional temperature increase in the middle of the veneer panel laminate only occurs after a certain delay time, which is necessary for heating the peripheral areas. The subsequent temperature increase only occurs very slowly. Since the veneer laminates are made very thick (30 mm - 150 mm), the pressing process still takes between 10 minutes and 45 minutes.
Summary of the Invention The objective of the invention is a method and apparatus by which a higher quality of veneer laminate can be manufactured in continuous production and by which a greater throughput can be achieved through quicker processing.
In accordance with one aspect of the present invention there is provided a method of manufacturing endless veneer laminates from a strand of veneer panels made of veneer panels in multiple layers superimposed on each other and behind each other and with intermediate layers of glue by means of gluing and pressing in a heated, continuously operating press, said method comprising the following steps: (a) pressing the strand of veneer panels together under light pressure before or during preheating in such a way that the veneer panels lie flat one on top of the other; (b) passing the strand of veneer panels through an RF (radio frequency) or MW (microwave frequency) heating section until the respective curing temperature of the glue is reached or slightly exceeded in the strand; (c) prepressing the heated strand of veneer panels at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press; and (d) pressing the strand of veneer panels in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW heating section until it has reached a desired panel thickness and glue seams have cured.
In accordance with another aspect of the present invention there is provided a method of manufacturing endless OSB, LSL (laminated strand lumber) or wafer panels from a strand of wood particles of long chips or wood waffles, spread in multiple layers superimposed on each other and behind each other, by gluing and pressing in a heated, continuously operating press, said method comprising the steps of: (a) prior to preheating, precompressing the strand under light pressure in such a way that the wood particles lie firmly against or upon each other; (b) while maintaining the precompression thickness passing the strand through an RF or MW heating section until the respective curing temperature of the glue has been reached or slightly exceeded in the strand; (c) prepressing the heated strand at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press; and (d) pressing the partially cured strand in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW heating section until it has reached a desired panel thickness and is cured.
In accordance with yet another aspect of the present invention there is provided an apparatus for carrying out the method according to any one of claims 1 to 5 for manufacturing endless veneer laminates from an endless string of veneer panels or for manufacturing OSB, LSL or wafer board from an endless string of spread wood particles, comprising a feeding device for the strand of veneer panels or the strand, an RF or MW heating device, a prepress and a continuously operating press, the RF
or MW
heating device having an entry and an exit shielding device and that a prepress is located downstream from it whose pressing range, including a transfer nose and a transfer plate, extends almost to the clamping area of the continuously operating press, and that the material to be pressed can be subjected to a pressing pressure of between 5 and 30 bar surface pressure or between 3 and 20 N/mrn linear pressure when passing through the prepress.
More specifically, according to an embodiment of the present invention, a method for the continuous production of LVL panels or veneer laminates lies in the implementation of the following steps:
First, the strand of veneer panels is pressed together before or during preheating in such a way that the veneer panels lie flat one on top of the other. In a second step, the strand of veneer panels passes through an RF or MW heating section until the respective curing temperature of the applied glue is reached or slightly exceeded in the strand.
Following this, the heated strand of veneer panels is prepressed at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press.
Finally, the strand of veneer panels is pressed in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW heating section until it has reached the final panel thickness and the glue seams have cured completely.
More specifically, according to an embodiment of the present invention, an apparatus for carrying out the above method (for example) includes a RF or MW
heating device having an entry and an exit shielding device and that a prepress is located downstream from it whose pressing range, including the transfer nose and (if applicable) the transfer plate, extends almost to the clamping area of the continuously operating press, and that the material to be pressed can be subjected to a pressing pressure of between 5 and 30 bar surface pressure or between 3 and 20 N/mm linear pressure when passing through the prepress.
Compared to state-of-the-art technology, the advantage is that the process and facility according to the invention can significantly increase the productivity of the continuously operating production facility as well as provide a more gentle compression and, therefore, improved product quality. To this end, the strand of veneer panels is initially covered between two conveyer belts and the waviness of the veneer panels is pressed flat under light pressure, so that the individual veneer panels lie snug against each other. In this state, the strand of veneer panels is preheated to the respective curing temperature of the glue or slightly higher by means of RF (high frequency) or MW
(microwaves). Only after preheating is the strand of veneer panels compressed in a continuously operating prepress under a pressure of 5 to 30 bar surface pressure or 3 to 20 N/mm linear pressure. The rollers of the prepress are arranged so close together that no significant spring-back of the strand of veneer panels occurs between the rollers.
If compression of the veneer panels occurs after preheating, the wood fibres are already in a plastic state due to the high temperature and can be compressed with minimal force and without breaking. It was determined that this procedure results in the end product having measurably better flectional strength with the same veneer laminate quality.
However, it is crucial that the preheating temperature can be increased to the required curing temperature of the glue, thus ensuring that the reaction of the glue begins immediately after leaving the preheating section. The strand of veneer panels is compressed and pressed directly at the start of the curing reaction. This prevents premature curing or drying of the glue seams. The facility is designed in such a way that the transfer components of the prepress project far into the intake mouth of the main press and transfer the strand of veneer panels (which at this point is already partially cured) almost without transition to the steel belts of the main press.
Since the required curing temperature has already been reached in the strand of veneer panels, no significant temperature increase is necessary in the main press, but rather a moderation or minor increase in the temperature of the steel belts in order to prevent the veneer panels from cooling and to cure the glue.
The strand in the continuously operating press is pressed and cured at the usual temperature and pressure used in the manufacture of veneer laminates or OSB, LSL and wafer board.
When applying the model according to an example of the invention for manufacturing OSB, LSL (laminated strand lumber) or wafer board in a first step, the strand is compressed under light pressure prior to preheating in such a way that the wood particles lie firmly against or upon each other. In a second step, while maintaining the precompression thickness, the strand passes through an RF or MW
heating section until the respective curing temperature of the applied glue has been reached or slightly exceeded in the strand. Following this, the heated strand is prepressed at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press, and the already partially cured strand is pressed in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW heating section until it has reached the final panel thickness and is completely cured.
When manufacturing veneer laminates from veneer panels of high quality, i.e.
with the characteristic of greater waviness, and when manufacturing OS or LSL
or wafer board, it is advantageous to precompress the strand of veneer panels for veneer laminate with a pressure of 0.0004 to 2.0 bar and the strand for OSB/LSL
panels with a pressure of S to 30 bar surface pressure or 3 to 20 N/mm linear pressure and to feed them into the RF or MW heating device with this precompression thickness.
Brief Description of the Drawings Further features and advantages of the present invention will be described in the detailed description, taken in combination with the appended drawings, in which:
Figure 1 shows a side view of the facility for carrying out the process according to the invention; and Figure 2 shows the facility according to Figure 1 with a prepress that projects back into the RF or MW heating device.
Detailed Description of Embodiments of the Present Invention In Figures 1 and 2, the apparatus for carrying out the process is shown as a complete side view. Its main components are a feeding device 2 for an endless strand 1 of veneer panels or long chips, waffles, etc., an RF or MW heating device 8 with shielding devices ''HA", a prepress 12 and a continuously operating press 3.
In order to simplify the drawing and the following description, the endless strand of veneer panels 1 according to the application of the invention according to the manufacture of veneer laminates and the endless strand 1 according to the application of the invention according to the manufacture of OSB, LSL or wafer board are each identified by the reference symbol 1. Further, the term ''HA" represents an RF or MW heating device with a shielding device; "HV" represents HA plus a prepress and HS represents an RF
or M W heating section.
To further clarify the invention, the example of an embodiment shows a continuously operating press 3, which is designed as a dual-belt press with circulating steel belts 15 and 16 and heated pressure/heating plates 17. The heated and prepressed strand 1 is fed into a press slot of the continuously operating press 3 via idler drums 18 and 19, the press slot being adjustable in relation to a stationary press table 20 by means of a press rammer 21 that can be raised and lowered. A prepress 12 is located directly in front of ingoing steel belts 15 and 16 of the continuously operating press 3.
The illustration of RF or MW heating device 8 shows the allocation of an upper circulating plastic belt 5 and a lower circulating plastic belt 4 to the strand 1 passing through, the upper plastic belt 5 enveloping the upper surface of the material to be pressed and the lower plastic belt 4 enveloping the lower surface of the material to be pressed, whereby the upper plastic belt 5 is guided over a non-conductive Teflon plate 7 serving as a slideway lining. Both the plastic belts 4 and 5 are each guided over idler rollers 24 and, in the intake area of the continuously operating press 3, around transfer noses 13 and, if applicable, a transfer plate 25 in the press slot of the prepress 12 and, in the heating tunnel, circulate around the EZF or MW heating device 8 with shielding device ''I-IA" and prepress ''HV" (high frequency or microwave heating device). The strand 1 arriving in feeding direction 9 at the apparatus from a placement device or spreading station is taken over by the feeding device 2, the lower plastic belt 4 taking over the strand 1 and, while the upper plastic belt 5 holds it down, feeding it into the RF or MW
heating device 8 with shielding device "HA" and the prepress ''HV". If necessary, the strand 1 .
is slightly precompressed by means of precompressing rollers 6 and then fed to the RF
or MW heating device 8. In order to prevent any damage from RF or MW rays, an entry and an exit shielding device 10 and 11 is arranged upstream from the RF or MW
heating section "HS".
The prepress 12 includes multiple rollers 14 that form the press slot and pick up the preheated strand 1 by means of an arrangement similar to mangles, presses it and then feeds it to the continuously operating press 3. 'the rollers 14 are mounted in an upper and a lower press spar 23, whereby the upper press spar 23 can be raised and lowered in the press uprights 22. Depending on the product requirements, the press spars 23 can project back into the exit shielding device 11 and into the heating section ''HS", i.e. it may be necessary to extend the pressing range of the prepress 12 back to the RF or MW heating section "HS", where a temperature between 70 degrees Celsius and 85 degrees Celsius, the maximum temperature in the strand 1, has already been reached.
heating device having an entry and an exit shielding device and that a prepress is located downstream from it whose pressing range, including the transfer nose and (if applicable) the transfer plate, extends almost to the clamping area of the continuously operating press, and that the material to be pressed can be subjected to a pressing pressure of between 5 and 30 bar surface pressure or between 3 and 20 N/mm linear pressure when passing through the prepress.
Compared to state-of-the-art technology, the advantage is that the process and facility according to the invention can significantly increase the productivity of the continuously operating production facility as well as provide a more gentle compression and, therefore, improved product quality. To this end, the strand of veneer panels is initially covered between two conveyer belts and the waviness of the veneer panels is pressed flat under light pressure, so that the individual veneer panels lie snug against each other. In this state, the strand of veneer panels is preheated to the respective curing temperature of the glue or slightly higher by means of RF (high frequency) or MW
(microwaves). Only after preheating is the strand of veneer panels compressed in a continuously operating prepress under a pressure of 5 to 30 bar surface pressure or 3 to 20 N/mm linear pressure. The rollers of the prepress are arranged so close together that no significant spring-back of the strand of veneer panels occurs between the rollers.
If compression of the veneer panels occurs after preheating, the wood fibres are already in a plastic state due to the high temperature and can be compressed with minimal force and without breaking. It was determined that this procedure results in the end product having measurably better flectional strength with the same veneer laminate quality.
However, it is crucial that the preheating temperature can be increased to the required curing temperature of the glue, thus ensuring that the reaction of the glue begins immediately after leaving the preheating section. The strand of veneer panels is compressed and pressed directly at the start of the curing reaction. This prevents premature curing or drying of the glue seams. The facility is designed in such a way that the transfer components of the prepress project far into the intake mouth of the main press and transfer the strand of veneer panels (which at this point is already partially cured) almost without transition to the steel belts of the main press.
Since the required curing temperature has already been reached in the strand of veneer panels, no significant temperature increase is necessary in the main press, but rather a moderation or minor increase in the temperature of the steel belts in order to prevent the veneer panels from cooling and to cure the glue.
The strand in the continuously operating press is pressed and cured at the usual temperature and pressure used in the manufacture of veneer laminates or OSB, LSL and wafer board.
When applying the model according to an example of the invention for manufacturing OSB, LSL (laminated strand lumber) or wafer board in a first step, the strand is compressed under light pressure prior to preheating in such a way that the wood particles lie firmly against or upon each other. In a second step, while maintaining the precompression thickness, the strand passes through an RF or MW
heating section until the respective curing temperature of the applied glue has been reached or slightly exceeded in the strand. Following this, the heated strand is prepressed at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press, and the already partially cured strand is pressed in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW heating section until it has reached the final panel thickness and is completely cured.
When manufacturing veneer laminates from veneer panels of high quality, i.e.
with the characteristic of greater waviness, and when manufacturing OS or LSL
or wafer board, it is advantageous to precompress the strand of veneer panels for veneer laminate with a pressure of 0.0004 to 2.0 bar and the strand for OSB/LSL
panels with a pressure of S to 30 bar surface pressure or 3 to 20 N/mm linear pressure and to feed them into the RF or MW heating device with this precompression thickness.
Brief Description of the Drawings Further features and advantages of the present invention will be described in the detailed description, taken in combination with the appended drawings, in which:
Figure 1 shows a side view of the facility for carrying out the process according to the invention; and Figure 2 shows the facility according to Figure 1 with a prepress that projects back into the RF or MW heating device.
Detailed Description of Embodiments of the Present Invention In Figures 1 and 2, the apparatus for carrying out the process is shown as a complete side view. Its main components are a feeding device 2 for an endless strand 1 of veneer panels or long chips, waffles, etc., an RF or MW heating device 8 with shielding devices ''HA", a prepress 12 and a continuously operating press 3.
In order to simplify the drawing and the following description, the endless strand of veneer panels 1 according to the application of the invention according to the manufacture of veneer laminates and the endless strand 1 according to the application of the invention according to the manufacture of OSB, LSL or wafer board are each identified by the reference symbol 1. Further, the term ''HA" represents an RF or MW heating device with a shielding device; "HV" represents HA plus a prepress and HS represents an RF
or M W heating section.
To further clarify the invention, the example of an embodiment shows a continuously operating press 3, which is designed as a dual-belt press with circulating steel belts 15 and 16 and heated pressure/heating plates 17. The heated and prepressed strand 1 is fed into a press slot of the continuously operating press 3 via idler drums 18 and 19, the press slot being adjustable in relation to a stationary press table 20 by means of a press rammer 21 that can be raised and lowered. A prepress 12 is located directly in front of ingoing steel belts 15 and 16 of the continuously operating press 3.
The illustration of RF or MW heating device 8 shows the allocation of an upper circulating plastic belt 5 and a lower circulating plastic belt 4 to the strand 1 passing through, the upper plastic belt 5 enveloping the upper surface of the material to be pressed and the lower plastic belt 4 enveloping the lower surface of the material to be pressed, whereby the upper plastic belt 5 is guided over a non-conductive Teflon plate 7 serving as a slideway lining. Both the plastic belts 4 and 5 are each guided over idler rollers 24 and, in the intake area of the continuously operating press 3, around transfer noses 13 and, if applicable, a transfer plate 25 in the press slot of the prepress 12 and, in the heating tunnel, circulate around the EZF or MW heating device 8 with shielding device ''I-IA" and prepress ''HV" (high frequency or microwave heating device). The strand 1 arriving in feeding direction 9 at the apparatus from a placement device or spreading station is taken over by the feeding device 2, the lower plastic belt 4 taking over the strand 1 and, while the upper plastic belt 5 holds it down, feeding it into the RF or MW
heating device 8 with shielding device "HA" and the prepress ''HV". If necessary, the strand 1 .
is slightly precompressed by means of precompressing rollers 6 and then fed to the RF
or MW heating device 8. In order to prevent any damage from RF or MW rays, an entry and an exit shielding device 10 and 11 is arranged upstream from the RF or MW
heating section "HS".
The prepress 12 includes multiple rollers 14 that form the press slot and pick up the preheated strand 1 by means of an arrangement similar to mangles, presses it and then feeds it to the continuously operating press 3. 'the rollers 14 are mounted in an upper and a lower press spar 23, whereby the upper press spar 23 can be raised and lowered in the press uprights 22. Depending on the product requirements, the press spars 23 can project back into the exit shielding device 11 and into the heating section ''HS", i.e. it may be necessary to extend the pressing range of the prepress 12 back to the RF or MW heating section "HS", where a temperature between 70 degrees Celsius and 85 degrees Celsius, the maximum temperature in the strand 1, has already been reached.
Claims (11)
1. A method of manufacturing endless veneer laminates from a strand of veneer panels made of veneer panels in multiple layers superimposed on each other and behind each other and with intermediate layers of glue by means of gluing and pressing in a heated, continuously operating press, said method comprising the following steps:
(a) pressing the strand of veneer panels together under light pressure before or during preheating in such a way that the veneer panels lie flat one on top of the other;
(b) passing the strand of veneer panels through an RF (radio frequency) or MW (microwave frequency) heating section until the respective curing temperature of the glue is reached or slightly exceeded in the strand;
(c) prepressing the heated strand of veneer panels at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press; and (d) pressing the strand of veneer panels in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW
heating section until it has reached a desired panel thickness and glue seams have cured.
(a) pressing the strand of veneer panels together under light pressure before or during preheating in such a way that the veneer panels lie flat one on top of the other;
(b) passing the strand of veneer panels through an RF (radio frequency) or MW (microwave frequency) heating section until the respective curing temperature of the glue is reached or slightly exceeded in the strand;
(c) prepressing the heated strand of veneer panels at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press; and (d) pressing the strand of veneer panels in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW
heating section until it has reached a desired panel thickness and glue seams have cured.
2. A method of manufacturing endless OSB, LSL (laminated strand lumber) or wafer panels from a strand of wood particles of long chips or wood waffles, spread in multiple layers superimposed on each other and behind each other, by gluing and pressing in a heated, continuously operating press, said method comprising the steps of:
(a) prior to preheating, precompressing the strand under light pressure in such a way that the wood particles lie firmly against or upon each other;
(b) while maintaining the precompression thickness passing the strand through an RF or MW heating section until the respective curing temperature of the glue has been reached or slightly exceeded in the strand;
(c) prepressing the heated strand at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press; and (d) pressing the partially cured strand in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW
heating section until it has reached a desired panel thickness and is cured.
(a) prior to preheating, precompressing the strand under light pressure in such a way that the wood particles lie firmly against or upon each other;
(b) while maintaining the precompression thickness passing the strand through an RF or MW heating section until the respective curing temperature of the glue has been reached or slightly exceeded in the strand;
(c) prepressing the heated strand at a pressure of 5 to 30 bar surface pressure or 3 - 20 N/mm linear pressure and fed to within a few millimetres of and then into the clamping area of the continuously operating press; and (d) pressing the partially cured strand in the continuously operating press while maintaining or increasing the temperature reached in the RF or MW
heating section until it has reached a desired panel thickness and is cured.
3. The method according to claim 1 or 2, wherein the strand in the continuously operating press is pressed and cured at the usual temperature and pressure used in the manufacture of veneer laminates or OSB, LSL and wafer board.
4. The method according to claim 1 or 3, wherein a slight pressing down of the strand under 0.005 to 2.0 bar occurs before the strand of veneer panels is transferred to the RF or MW heating section.
5. The method according to claim 2 or 3, wherein a precompression under 5 to 30 bar surface pressure or 3 to 20 N/mm linear pressure is carried out before the strand of veneer panels is transferred to the RF or MW heating section.
6. An apparatus for carrying out the method according to any one of claims 1 to 5 for manufacturing endless veneer laminates from an endless string of veneer panels or for manufacturing OSB, LSL or wafer board from an endless string of spread wood particles, comprising a feeding device for the strand of veneer panels or the strand, an RF or MW heating device, a prepress and a continuously operating press, the RF or MW heating device having an entry and an exit shielding device and that a prepress is located downstream from it whose pressing range, including a transfer nose and a transfer plate, extends almost to the clamping area of the continuously operating press, and that the material to be pressed can be subjected to a pressing pressure of between 5 and 30 bar surface pressure or between 3 and 20 N/mm linear pressure when passing through the prepress.
7. The apparatus according to claim 6, further comprising an endless plastic belt, lying on the strand, is guided to circulate around the upper part of the RF or MW
heating device with shielding devices and prepress and in that a second endless plastic belt is arranged to circulate around the lower part of the RF or MW heating device with shielding device and prepress, carrying and pulling the strand through the heating tunnel and press slot of the prepress.
heating device with shielding devices and prepress and in that a second endless plastic belt is arranged to circulate around the lower part of the RF or MW heating device with shielding device and prepress, carrying and pulling the strand through the heating tunnel and press slot of the prepress.
8. The apparatus according to claim 6 or 7, wherein the pressing range of the prepress projects back to a point in the exit shielding device and in the RF or MW
heating device at which the maximum strand temperature has been reached.
heating device at which the maximum strand temperature has been reached.
9. The apparatus according to one of claims 6 to 8, wherein the pressing range of the prepress projects back to a point in the exit shielding device and in the RF
or MW heating device at which a temperature between 70 degrees Celsius and 85 degrees Celsius has already been reached in the strand.
or MW heating device at which a temperature between 70 degrees Celsius and 85 degrees Celsius has already been reached in the strand.
10. The apparatus according to one of claims 6 to 9, wherein under the upper part of the RF or MW heating device with shielding device, a Teflon plate is attached as a slideway lining for the upper plastic belt.
11. The apparatus according to one of claims 6 to 10, further comprising precompressing rollers located in front of the entry shielding device, pressing slightly on the upper plastic belt.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2000115416 DE10015416A1 (en) | 2000-03-28 | 2000-03-28 | Manufacture of endless veneer laminate from series of sheets by pre-pressing after heating to curing temperature of glue |
| DE10015416.6 | 2000-03-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2342840A1 true CA2342840A1 (en) | 2001-09-28 |
Family
ID=7636716
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002342840A Abandoned CA2342840A1 (en) | 2000-03-28 | 2001-03-28 | Method and apparatus for manufacturing endless veneer laminates |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA2342840A1 (en) |
| DE (1) | DE10015416A1 (en) |
| FI (1) | FI20010627A (en) |
| SE (1) | SE519153C2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011051568A1 (en) * | 2009-10-28 | 2011-05-05 | Upm-Kymmene Wood Oy | Method for manufacturing wood board and wood board |
| WO2011051566A1 (en) * | 2009-10-28 | 2011-05-05 | Upm-Kymmene Wood Oy | Method and apparatus for manufacturing plywood |
| WO2016201553A1 (en) * | 2015-06-15 | 2016-12-22 | Fpinnovations | Radio-frequency methods for engineered wood products |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100368164C (en) * | 2006-06-13 | 2008-02-13 | 车炳雷 | Artificial timber curing process |
| DE102011103129A1 (en) * | 2011-05-25 | 2012-11-29 | Wemhöner Surface Technologies GmbH & Co. KG | Method and apparatus for hot-pressing adhesive-provided component stacks for producing sandwich lightweight panels with integrated wooden frame core |
| DE102015117532B3 (en) * | 2015-10-15 | 2017-03-16 | Dieffenbacher GmbH Maschinen- und Anlagenbau | Method and device for the continuous production of laminated veneer sheets |
| DE102019113686B4 (en) * | 2019-02-22 | 2024-04-25 | Wooden-3D-Tubing UG (haftungsbeschränkt) | Method and device for producing a wooden profile |
-
2000
- 2000-03-28 DE DE2000115416 patent/DE10015416A1/en not_active Ceased
-
2001
- 2001-03-20 SE SE0100963A patent/SE519153C2/en not_active IP Right Cessation
- 2001-03-27 FI FI20010627A patent/FI20010627A/en unknown
- 2001-03-28 CA CA002342840A patent/CA2342840A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011051568A1 (en) * | 2009-10-28 | 2011-05-05 | Upm-Kymmene Wood Oy | Method for manufacturing wood board and wood board |
| WO2011051566A1 (en) * | 2009-10-28 | 2011-05-05 | Upm-Kymmene Wood Oy | Method and apparatus for manufacturing plywood |
| WO2016201553A1 (en) * | 2015-06-15 | 2016-12-22 | Fpinnovations | Radio-frequency methods for engineered wood products |
Also Published As
| Publication number | Publication date |
|---|---|
| SE519153C2 (en) | 2003-01-21 |
| DE10015416A1 (en) | 2001-10-04 |
| SE0100963D0 (en) | 2001-03-20 |
| FI20010627A (en) | 2001-09-29 |
| FI20010627A0 (en) | 2001-03-27 |
| SE0100963L (en) | 2001-09-29 |
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