Apparatus and method for microwave curing of resins in engineered wood products

A system for producing dimensioned material using a fibrous component and a binder material which are organized in layers into a billet, where the billet has a longitudinal axis, said system utilizing microwaves to heat the billets either in a press with platens or in a preheating stage before the billet is pressed, by illuminating the billet with an incident traveling wave of microwave energy which passes through the billet, is reflected back through the billet as a reflected wave, the reflected wave is sensed, and tuned to cancel a reflected microwave energy, said system comprising:

• a heating chamber through which the billet is passed;
• at least one microwave energy generator for generating circular magnetic mode microwave energy;
• at least one circular mode microwave applicator connecting said generator to said heating chamber directing said circular magnetic mode microwave energy into said chamber;
• at least one microwave reflecting surface in the heating chamber adjacent a side of the billet opposite the microwave applicator, for reflecting a circular magnetic mode microwave energy wave which exits an opposite side of the billet directly back into the billet toward the microwave applicator;
• and
• one or more sensors of microwave energy for measuring said reflected microwave energy wave and reporting measured reflected microwave energy to a computer tuning system said computer tuning system using the measured microwave energy to calculate and make adjustments required to reduce the reflected microwaves traveling toward the microwave generator to approximately zero.

An apparatus for producing dimensioned material from a billet made of a fibrous component and a binder material, said apparatus utilizing microwaves to heat the billets in a heating chamber either in a press with platens while the billet is pressed or in a preheating stage before the billet is pressed, by illuminating the billet in the chamber with an incident traveling wave of microwave energy which passes through the billet, reflects off of a heating chamber surface and reflects back into the billet as a reflected wave, said apparatus comprising:

• a heating chamber through which said billet passes before or during pressing of the billet, said chamber having opposing surfaces;
• a microwave source producing microwave energy;
• and
• a wave-guide network including a circular magnetic mode converter for converting said microwave energy into circular magnetic mode microwave energy, said network connecting the microwave source to the heating chamber and directing said circular magnetic mode microwave energy into said chamber through a microwave transparent aperture in one of said opposing wall surfaces of said chamber;
• said heating chamber having a microwave reflective surface therein opposite said one wall surface for reflecting circular magnetic mode microwave energy emerging from a billet positioned in said chamber back toward said one wall surface through said billet positioned in said chamber.

An apparatus for producing dimensioned material from a billet made of a fibrous component and a binder material, said apparatus utilizing microwaves to heat the billets in a heating chamber having opposing surfaces either in a press with platens or in a preheating stage before the billet passes into said press, by illuminating the billet in the chamber with an incident traveling wave of circular magnetic mode microwave energy which passes through the billet, reflects off of a heating chamber surface and reflects back into the billet as a reflected wave, said apparatus comprising:

• a heating chamber through which said billet passes before or during pressing of the billet, said chamber having opposing wall surfaces;
• a microwave source producing circular magnetic mode microwave energy;
• and
• a circular magnetic mode applicator connecting the microwave source to the heating chamber and directing said circular magnetic mode microwave energy into said chamber through an aperture in one of said opposing wall surfaces of said chamber;
• a microwave reflective surface opposite said one wall surface for reflecting circular magnetic mode microwave energy emerging from a billet positioned in said chamber back toward said one wall surface through said billet positioned in said chamber.

A method of making dimensioned material using a fibrous component and a binder material component which cures and in which a rate of curing is accelerated by heat, the two components being arranged in a billet with a center and a longitudinal axis, comprising the steps of:

• generating circular magnetic mode microwave energy with a microwave energy source for accelerating the curing of said binder material in said billet;
• directing said microwave energy into a heating chamber through which said billet must pass;
• and
• illuminating the billet in the heating chamber with said circular magnetic mode microwave energy to heat said components and accelerate the curing rate.

A method of making dimensioned material using a fibrous component and a binder material component which cures and in which a rate of curing is accelerated by heat, the two components being arranged in a billet with a center and a longitudinal axis, comprising the steps of:

• combining the fibrous component and the binder material into a billet;
• generating microwave energy in a microwave source for curing the binder material in the billet;
• conducting the microwave energy from the microwave source through a rectangular microwave wave guide network as rectangular wave guide mode microwave energy;
• converting said rectangular wave guide mode microwave energy to other than rectangular wave guide mode microwave energy in a mode converter;
• directing said other than rectangular wave guide mode microwave energy into a heating chamber through a microwave transparent window into said heating chamber;
• passing said billet through said heating chamber;
• and
• illuminating the billet in the heating chamber with a traveling wave of said other than rectangular wave guide mode microwave energy to accelerate curing of said binder material in said billet.