Maschinenfabrik J. Dieffenbacher Gmbh Co.

Maschinenfabrik J. Dieffenbacher

Mashinenfabrik J. Dieffenbacher Gmbh & Co.

Werner Hoffmann

Friedrich B Bielfeldt

Gerhard M Melzer

The invention relates to a process for the production of boards of wood-based material from a mixture of lignocellulose- and/or cellulose-containing particles mixed with a binder, the mat or pressed stock being preheated by means of high-frequency (HF) or microwave (MW) energy and, after transfer into a single or multi-platen press or a continuously operating press, being pressed and cured by the application of pressure and heat. To increase the preheating temperature of the pressed stock and to reduce the pressing factor, the following process steps are provided: (a) the preheating in the core of the mat of pressed stock to &gE;85&deg; Celsius takes place after or during the precompaction by traveling wave microwave energy and its reflection in an interaction between emitted and reflected energy into the center of the mat of pressed stock, a. focusing of the radiation energy into the center cross section being performed at a large energy-introduction and energy-absorption angle &bgr;, for an increased heat gradient, and (b) the preheated mat of pressed stock enters the pressing region of the press with a moisture content which is 15% to 30% less than the conventionally-controlled moisture content.

Apparatus for the production of boards of wood-based material

The invention relates to a process for the production of boards of wood-based material from a mixture of lignocellulose- and/or cellulose-containing particles mixed with a binder, the mat or pressed stock being preheated by means of high-frequency (HF) or microwave (MW) energy and, after transfer into a single or multi-platen press or a continuously operating press, being pressed and cured by the application of pressure and heat. To increase the preheating temperature of the pressed stock and to reduce the pressing factor, the following process steps are provided: (a) the preheating in the core of the mat of pressed stock to &gE;85&deg; Celsius takes place after or during the precompaction by traveling wave microwave energy and its reflection in an interaction between emitted and reflected energy into the center of the mat of pressed stock, a focusing of the radiation energy into the center cross section being performed at a large energy-introduction and energy-absorption angle &bgr;, for an increased heat gradient, and (b) the preheated mat of pressed stock enters the pressing region of the press with a moisture content which is 15% to 30% less than the conventionally-controlled moisture content.

Process for the production of boards of wood-based material

Veneer panels which are to be joined in a plurality of layers one above the other and one behind the other are assembled and glued to form an endless strand of veneer laminates. In the process, the veneer panels are first fed in through a glue-application machine which applies a layer of glue on a top side of the veneer panels onto a buffer belt. The veneer panels are then transferred from the buffer belt to a horizontally reversing feed belt which forms on a roller table a first veneer assembly comprising a plurality of veneer panels. The first veneer assembly is raised about its front end by an angle .alpha. into an oblique position so that veneer panels of a subsequent veneer assembly can be threaded into the first veneer assembly using the horizontally reversing feed belt. The first and subsequent veneer assemblies are thereby combined into a veneer-panel strand, and transferred to a continuously operating prepress and press.

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Eppingen, Germany

Werner Hoffmann