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The invention relates to a method and device with which it is possible to arrange complicated shapes with considerable differences in height in wood fibre board, and in particular but not exclusively so-called MDF (Medium Density Fibreboard). The deformation of the wood fibre board which can be achi

The invention relates to a method and device with which it is possible to arrange complicated shapes with considerable differences in height in wood fibre board, and in particular but not exclusively so-called MDF (Medium Density Fibreboard). The deformation of the wood fibre board which can be achieved with the invention is known in the art as extrusion, wherein a considerable plastic deformation takes place accompanied by flow and stretch of the material.

대표청구항 ▼

1. Method of deforming a wood fibre board blank into a shaped product in a mould cavity in a press having at least an upper mould and lower mould, at least one of the upper mould and the lower mould movable toward the other from a first open position for receiving the blank to a second closed positi

1. Method of deforming a wood fibre board blank into a shaped product in a mould cavity in a press having at least an upper mould and lower mould, at least one of the upper mould and the lower mould movable toward the other from a first open position for receiving the blank to a second closed position defining the mould cavity, the method comprising:heating the blank to a thermo softening point such that the material of the blank is plastically deformable; providing the mould cavity in the closed position with at least one constriction adapted to restrict lateral extrusion flow of the softened material of the blank, the constriction located to prevent defects in the shaped product; heating at least one of the upper mould and the lower mould; and pressing the blank in the mould cavity in a pressing cycle comprising at least one period of gradual progressive deforming followed by at least one period of rest while heating without opening the mould cavity. 2. Method as claimed in claim 1, wherein heating of the board comprises steam treatment of the board.3. Method as claimed in claim 2, comprising of heating the board in a closed space and, prior to heating, further reducing the pressure in the space and introducing the steam into the space in a free flow.4. Method as claimed in claim 3, further comprising of heating at least the ceiling of the space to a higher temperature than the space.5. Method as claimed in claim 3, further comprising heating the walls of the space.6. Method as claimed in claim 1, wherein pressing takes place in conjunction with the heating of the mould parts or holders therefore applied in the pressing.7. Method as claimed in claim 1, wherein the pressing comprises a pressing cycle with at least one decrease to an approximately pressureless state and a subsequent increase of the pressure on mould parts used during the pressing.8. Method as claimed in claim 1, wherein the pressing comprises of rapid closing of mould parts used therein and relatively slow build-up and decrease in the pressure.9. Method as claimed in claim 1, further comprising pressing, together with the board, a cover layer for covering the board subjected to the pressing.10. Method as claimed in claim 1, further comprising of arranging a relief, during the pressing, in the visual surface of the board subjected to the pressing.11. Device for deforming a wood fibre board blank into a shaped product comprising:a means for heating the blank to a thermo softening point such that the material of the blank is plastically deformable; a press having at least an upper mould and a lower mould, at least one of the upper mould and lower mould movable toward the other from a first open position for receiving the blank to a second closed position defining a mould cavity; and at least one constriction in the mould cavity in the closed position, the constriction adapted to restrict lateral extrusion flow of the softened material of the blank, the constriction located to prevent defects in the shaped product; wherein at least one of the upper mould and the lower mould is adapted to be heated and wherein the apparatus is adapted to press the blank in the mould apparatus is adapted to press the blank in the mould cavity in a pressing cycle comprising at least one period of gradual progressive deforming followed by at lest one period of rest while heating without opening the mould cavity. 12. Device as claimed in claim 11, comprising heating means in at least a ceiling of a forming station operably associated with said press.13. Device as claimed in claim 11, further comprising heating means in the interior of the mould apparatus.14. Device as claimed in claim 13, wherein the heating means comprise guide channels for pre-heated oil.15. Device as claimed in claim 11, wherein the press comprises rapid-action coupling means for engaging selected mould parts.16. Device as claimed in claim 11, wherein the mould parts are sub-divided into at least two mould part components to be energized separately of each other.17. Device as claimed in claim 11, further comprising transport means for transporting the boards from and to the press.18. A method of manufacturing a hollow core door comprising the steps of:providing a wood composite flat blank; moisturizing the flat blank; pre-heating at least a surface of the flat blank to a temperature not exceeding approximately 100° C.; positioning the flat blank in a press between first and second platens, at least one of the first and second platens being heated; closing the press on the flat blank and reforming the flat blank into a molded door skin including a plurality of panels by applying a first pressure to the flat blank in the press and thereafter applying a second higher pressure to the flat blank in the press; affixing the molded door skin to a first side of a door frame; and affixing a second door skin to an opposite second side of the door frame. 19. Method as claimed in claim 18, wherein the step of pre-heating the blank comprises the step of applying steam to the blank.20. Method as claimed in claim 19, wherein the pre-heating of the blank occurs in a closed space and the steam is introduced into the closed space in a free flow form.21. Method as claimed in claim 20, wherein the closed space includes walls and a ceiling, the method further comprising the step of heating at least the ceiling of the space to a higher temperature than the temperature of the remainder of the space.22. Method as claimed in claim 21, further comprising the step of heating the walls of the space.23. Method as claimed in claim 19, wherein prior to the step of applying steam to the blank, the pressure in the space is reduced.24. Method as claimed in claim 19, including the additional step of heating the blank while the blank is reformed.25. Method as claimed in claim 18, wherein the step of reforming the flat blank comprises the steps of applying a first pressure to the flat blank in the press and reducing the pressure applied to the flat blank in the press to a level between said first pressure and atmospheric pressure.26. Method as claimed in claim 18, wherein the step of reforming the flat blank comprises the steps of applying a first pressure to the flat blank in the press and maintaining said first pressure for a predetermined period of time.27. Method as claimed in claim 18, wherein the step of closing the press on the flat blank comprises the step of closing the press on the flat blank at a first rate, and the step of reforming the flat blank comprises slowly increasing the pressure applied to the flat blank and then slowly decreasing the pressure applied to the flat blank.28. Method as claimed in claim 18, further comprising the step of providing a covering layer to the flat blank after the pre-heating step.29. Method as claimed in claim 18, further comprising the step of developing a relief on the surface of the flat blank during the reforming step.30. Method as claimed in claim 18, including the step of holding the temperature of the platens in a pre-selected range during the reforming step.31. Method as claimed in claim 18, further comprising the step of maintaining a geometrically uniform gap between said first and second platens during the reforming step.32. Method as claimed in claim 18, further comprising the step of reforming the blank into a plurality of molded door skins.33. Method as claimed in claim 32, further comprising the step of forming a pinch between adjacent molded door skins to facilitate the separation of the adjacent door skins from one another.34. Method as claimed in claim 18, further comprising the step of embossing a texture on the molded door skins during the reforming step.35. Method as claimed in claim 18, further comprising the step of providing material which includes a thermosetting resin to the pre-heated blank.36. Device for reforming a wood fiber board blank into a finished product having areas of considerable difference in height relative to the original thickness of the wood fiber board blank, comprising:a first station with a blank heater and a blank moisturizer; a second station for pressing a blank to a desired form, said second station comprising: first and second opposing platens each having a mold attached thereto; and a controller for controlling the opening and closing of the platens and the amount of pressure applied to a blank positioned between the platens; said controller gradually increasing the pressure on a blank to a predetermined pressure, maintaining the predetermined pressure at a predetermined level for a predetermined period of time and gradually reducing the pressure to approximately zero during a pressing cycle. 37. Device as claimed in claim 36, further comprising heating means in the interior of the platens or molds.38. Device as claimed in claim 36, including guide channels in at least one of said first and second platens for carrying heated oil.39. Device as claimed in claim 36 wherein the second station further comprises an attachment mechanism for connecting a mold to one of said first and second platens.40. Device as claimed in claims 36, further comprising a conveyor for conveying blanks to the first station, from the first station to the second station and from the second station.41. Device as claimed in claim 36 wherein said first and second molds have projections for reducing displacement of wood fiber material in a wood fiber board at locations between the molds where the blanks are subjected to the most severe shear loads during a pressing operation.42. Device as claimed in claim 36 further comprising automated means for switching the molds on the device.43. A door skin, comprising: a medium density fiber board flat blank that has been molded using heat, pressure and degassing into a three-dimensional blank, said fiber board blank being degassed while being molded into said three dimensional blank, said three dimensional blank having a first portion with a first preselected thickness and a second portion with a second preselected thickness less than said first preselected thickness.44. A hollow core door comprising:a door frame; a first door skin comprising a medium density fiberboard flat blank reformed into a three-dimensional blank having a plurality of panels and a second door skin attached to said door frame so as to define a hollow core area therebetween; said reformed door skin having a first molded portion with a first preselected thickness and a second molded portion with a second preselected thickness less than said first preselected thickness. 45. A press for molding door skins, comprising:first and second heatable platens; a plurality of openings in the side of at least one of said first and second platens for degassing; and an actuator for moving said first platen toward and away from the said second platen, thereby opening and closing the press.