Method of laser hardening corrugating rolls

Claim 1

A method of heat treating cylindrical corrugating rolls having a plurality of flutes extending along the length thereof, said rolls being formed for use in machinery for manufacturing corrugated paperboard, comprising the steps of: providing a laser having a Gaussian beam output; reconfiguring said beam from a Gaussian beam to a beam having a substantially homogeneous power density; positioning a focusing lens to receive and focus said homogeneous beam to provide a focused beam having a smaller cross-sectional area than the beam emitted by said laser; positioning a roll to be heat treated so that said focused beam is centered on a spot on one of said plurality of flutes; said spot having a smaller cross-sectional area than the beam emitted by said laser; hardening said one of said plurality of flutes by causing a relative movement between said roll and said focused beam in a direction parallel to the length of said roll.

Claim 2

A method of heat treating cylindrical corrugating rolls having a plurality of flutes extending along the length thereof, said rolls being formed for use in machinery for manufacturing corrugated paperboard, comprising the steps of: providing a laser having a Gaussian beam output; reconfiguring said beam from a Gaussian beam to a beam having a substantially homogeneous power density; positioning a focusing lens to receive and focus said homogeneous beam to provide a focused beam having a smaller cross-sectional area than the beam emitted by said laser; positioning a roll to be heat treated so that said focused beam is centered on a spot on one of said plurality of flutes; said spot having a smaller cross-sectional area than the beam emitted by said laser; hardening said one of said plurality of flutes by causing a relative movement between said roll and said focused beam in a direction parallel to the length of said roll.

Claim 18

A method of heat treating cylindrical corrugating rolls having a plurality of flutes extending along the length thereof, said rolls being formed for use in machinery for manufacturing corrugated paperboard, comprising the steps of: providing a CO 2 laser having a circular Gaussian beam output with a 11/2 inch diameter and an output power of 2.8 kW; positioning an integrator lens in front of said beam to reconfigure said beam from said Gaussian beam to a top hat beam, said top hat beam being focused to a 3/4 inch square having substantially homogeneous power density throughout its cross sectional area; positioning a focusing lens 25 inches from said integrator lens to receive and focus said top hat beam, said focusing lens having a focal length of 51/2 inches; coating a roll to be heat treated with a light absorbing coating; positioning said roll with a top portion of a first flute thereof located 10 inches from said focusing lens and centered within the beam from said focusing lens such that a square spot approximately 0.30 inch on each side is formed at a top portion of said flute, said square spot having a power density of approximately 30,000 W/in 2 ; said cross-sectional area being smaller than the beam emitted by said laser; hardening said flute by traversing said roll under said beam along the length of said flute at a rate of approximately 60 inches/minute to a depth of approximately 0.060 inch and a width across said flute of approximately 0.166 inch and to an average hardness of approximately 60-62 R c ; and repeating said steps for each flute on the roll.

Claim 19

A method of heat treating cylindrical corrugating rolls having a plurality of flutes extending along the length thereof, said rolls being formed for use in machinery for manufacturing corrugated paperboard, comprising the steps of: providing a CO 2 laser having a circular Gaussian beam output with a 11/2 inch diameter and an output power of 2.8 kW; positioning an integrator lens in front of said beam to reconfigure said beam from said Gaussian beam to a top hat beam, said top hat beam being focused to a 3/4 inch square having substantially homogeneous power density throughout its cross sectional area; positioning a focusing lens 25 inches from said integrator lens to receive and focus said top hat beam, said focusing lens having a focal length of 51/2 inches; coating a roll to be heat treated with a light absorbing coating; positioning said roll with a top portion of a first flute thereof located 10 inches from said focusing lens and centered within the beam from said focusing lens such that a square spot approximately 0.30 inch on each side is formed at a top portion of said flute, said square spot having a power density of approximately 30,000 W/in 2 ; said cross-sectional area being smaller than the beam emitted by said laser; hardening said flute by traversing said roll under said beam along the length of said flute at a rate of approximately 60 inches/minute to a depth of approximately 0.060 inch and a width across said flute of approximately 0.166 inch and to an average hardness of approximately 60-62 R c ; and repeating said steps for each flute on the roll.