Classifications

• • 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
  • B27N3/10—Moulding of mats

Definitions

• the present invention relates to a method for producing wood fiber boards according to the preamble of claim 1.
• Wood fiber boards are manufactured with a density of 600 to 1,100 kg / m3, depending on the board thickness. They are usually glued with urea, melamine, phenolic resins or with isocyanate. Wood fiber boards are usually produced in thicknesses of 2 to 5 mm.
• a key area of application is furniture construction.
• the fibreboard is made of the finest wood fibers and is particularly homogeneous.
• the plate can be painted or coated. Special edge banding techniques for thick boards are generally not required. The good workability of the narrow surfaces allows a particularly large variety of shapes. The prerequisite for this is a homogeneous structure and a density curve that is as uniform as possible over the entire panel thickness. The density must drop as little as possible towards the middle of the plate.
• the raw material for the production of fiberboard is mainly wood chips from softwood or hardwood, which are used in a defibration machine, e.g. B. a defibrator, brought into the desired fineness.
• a defibration machine e.g. B. a defibrator
• the wood fibers are then glued and dried to a wood moisture content of 6 to 15% dry.
• the glued wood fibers are then sprinkled mechanically in a molding station by means of molding heads onto a conveyor belt or sieve, on which a continuous non-woven fabric is formed.
• the still loose fiber fleece is pre-compacted with an unheated press to approx. 40% of the spreading strength.
• the resulting loose connection ensures good transport of the nonwoven.
• the pre-compressed nonwoven fabric is divided into individual sections, from which the wood fiber boards are then produced by pressing under pressure and temperature. After pressing, the plates are cooled and the top and bottom are sanded.
• the fiber mat can only be compressed to the extent that the pressure increases as the temperature inside the mat rises towards the center.
• the relatively poor heat conduction of the wood fiber fleece therefore requires slow compression due to a slow increase in pressure up to the desired thickness, with the destruction of the glue bridges in the outer surface layer area of the wood fiber boards having to be accepted as a disadvantage up to now.
• the result is that the insufficiently strong cover layers must then be ground down to the solid plate core formed. Depending on the thickness of the board, the grinding loss is between 20 and 30% for 10 to 20 mm thick boards.
• the present invention is therefore based on the object of demonstrating a method for producing wood fiber boards which, while maintaining all the special properties of the wood fiber board and while maintaining a homogeneous board structure, largely avoids the previous loss of abrasion of the high-quality board material.
• the method according to the invention offers a possibility of producing fiberboard which does not have the disadvantages described above.
• the drop in density over the entire board thickness is only slight and the sanding of the outer zones barely covers the fiber material used for the wood fiber board.
• the wood dust has the advantage of being extremely inexpensive and very easy to grind. Disposal can be done very easily by incineration. This procedure ensures that there is practically no longer any loss of the very expensive wood fiber board material and that, measured over the board thickness, only an extremely small decrease in density from outside to inside is found.
• the method can be designed to practically only grind off the pressed protective layers.
• the grinding is expediently carried out so deeply with a view to achieving a good grinding pattern and thus a corresponding surface that reliably no wood dust particles remain in the surface of the sanded plates, i.e. a thin boundary layer of the wood fiber board is sanded with.
• applications are also conceivable in which it may make sense to maintain a small proportion of the protective layer on at least one side of the wood fiber board. In such a case, the protective layer is then only partially ground off.
• wood dust used here as a protective layer for the pressing process does not entail any negative or unwanted impairment in the surface area of the wood fiber board.
• Both glued and non-glued wood dust of a certain grain size can be used to form the protective layer. If, for example, wood fiber nonwovens are present which still have sufficient adhesion to their surfaces when the wood dust is applied, the otherwise necessary glueing of the wood dust can be dispensed with.
• the special price-worthiness of the wood dust of a certain grain size used to form the protective layer results from the fact that filter and sieve dust, chip shavings, fibers from waste and the like can be used here without further notice.
• the use of wood dust particles in a certain grain size from chipboard production is possible, either in whole or in arbitrary proportions.
• the wood dusts from the combustible dust content of the sanding dust and the sieve dust from an adjacent particle board production can be used, so that practically these wood dusts are only disposed of after the second layer has been removed in connection with the wood fiber board production concerned, i.e. usually burned .
• Constant reuse for example to form new layers, does not make sense, since the material can accumulate to such an extent when it is used several times on the one hand with corundum from abrasive belts, on the other hand with hardened glue residues or mineral foreign bodies from the raw wood, so that this affects the fibreboard surface and damage the sanding belts.
• technological auxiliaries each in exact dosage, can also be added to the wood dust without any problems, which deliberately positively influence the properties of the wood fiber board and / or its production output.
• the curing of the binding agent of the fiberboard during the pressing can be advantageously carried out by appropriate hardeners, such as. B. accelerate ammonium chloride, ammonium sulfate or formic acid in urea resins.
• fungus protection agent to the wood dust, which is then stored in the cover layer areas of the wood fiber board when pressed.
• a fungus protection agent is added to the wood dust, which is then stored in the cover layer areas of the wood fiber board when pressed.
• a preferred technical adjuvant for admixture is also a hydrophobizing agent, which then also accumulates in the top layer area of the wood fiber board, which then reduces its water absorption capacity, which is advantageous for the special area of use of such wood fiber boards in damp rooms.
• the process is initially carried out as usual in the manufacture of the wood fiber boards up to and including the pre-compression of the fiber fleece.
• the fiber fleece is then coated on both sides with a layer of glued wood dust, the layer thickness being adjusted so that it is approximately 0.8 mm after pressing together with the wood fiber fleece.
• the sanding is adjusted to a thickness of 1 mm. This ensures with certainty that all wood dust particles are removed, the loss of wood fiber board material is minimal and the surface of the wood fiber board produced shows a perfect grinding pattern.
• the listed technological auxiliaries are added to the glued wood dust beforehand, depending on the need and application.
• the layer thickness can be set such that it is up to 3 mm after being pressed together with the wood fiber fleece. The sanding is then adjusted to an appropriate strength.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Dry Formation Of Fiberboard And The Like (AREA)
• Chemical And Physical Treatments For Wood And The Like (AREA)
• Artificial Filaments (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (3)

Family

ID=6308580

Family Applications (1)

Country Status (9)

Families Citing this family (12)

Family Cites Families (13)

• 1986
  • 1986-08-30 DE DE19863629586 patent/DE3629586A1/de not_active Withdrawn
• 1987
  • 1987-08-13 EP EP87111728A patent/EP0258703B1/fr not_active Expired - Lifetime
  • 1987-08-13 DE DE8787111728T patent/DE3768376D1/de not_active Expired - Fee Related
  • 1987-08-13 AT AT87111728T patent/ATE61274T1/de active
  • 1987-08-17 US US07/086,406 patent/US4883546A/en not_active Expired - Fee Related
  • 1987-08-25 AU AU77397/87A patent/AU580720B2/en not_active Ceased
  • 1987-08-28 CA CA000545603A patent/CA1284090C/fr not_active Expired - Fee Related
  • 1987-08-28 IE IE232087A patent/IE60071B1/en not_active IP Right Cessation
  • 1987-08-28 DK DK450587A patent/DK164691C/da active
  • 1987-08-31 NZ NZ221620A patent/NZ221620A/xx unknown

Also Published As

Similar Documents

Legal Events