Method and device for preheating a pressed material mat during manufacture of wood material boards

Abstract

The invention relates to a method for preheating a pressed material mat (14) spread on an endlessly and continuously circulating molding band (6) during manufacture of wood material boards, wherein microwaves from one or both press surface sides are beamed into the pressed material mat (14) to preheat the pressed material mat (14) and the pressed material mat (14) is compacted and hardened by application of pressure and heat after transfer to a continuously operating press (1). The invention consists of microwaves in a frequency range of 2400 - 2500 MHz being used to heat the pressed material mat (14), wherein the microwaves for each press surface side are generated from 20 to 300 microwave generators (26) with magnetrons (20) of a respective output of 3 to 50 kW. A device for preheating pressed material mats (14) is also provided, in which 20 to 300 microwave generators (26) with magnetrons (20) with an output of 3 to 50 kW and with a frequency range of 2400 - 2500 MHz are arranged in a conveyor furnace (4) per area side.

Description

technical field [0001] The invention relates to a method according to the preamble of claim 1 for preheating a pressed blank laid on an endlessly continuously circulating forming belt during the production of wood-based material panels and a method according to claim 1 Apparatus for preheating pressed blanks laid on an endlessly continuously circulating forming belt during the production of panels of wood material as described in the preamble of claim 15. Background technique [0002] It is known in the patent literature and in the industry that high-frequency technology is used as a means for preheating shaving or fibrous material in order to reduce the pressing factor during the pressing process which starts later in order to increase production efficiency. US 4,018,642 A discloses the use of microwaves as heat energy in plywood, particle board, particle board and sandwich panels, in which traveling waves with a frequency in the range of 100 MHz to 10 000 MHz are guided in...

AI Technical Summary

Problems solved by technology

[0007] As already stated, a further disadvantage is that if high-frequency or microwave frequencies are generated in a separate plant (usually directly next to the main current connection terminals) and have to be introduced into the production plant by means of waveguides until they are used, then consideration must be given to Considerable equipment-related outlay for ensuring the radiation safety of personnel and machines

In addition to the enormous waste of useful construction space, expensive radiation detectors have to be installed in safe areas against possible damage to these so-called waveguides

All of these make minimal maintenance (supervision) difficult and costly in terms of repairs and downtime

Although production will continue, the downtime of the equipment just by warming up can lead to economic losses of up to 30% for the business, because the suppression factor rises significantly without warming up and the production speed has to be reduced by a third

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