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US 5,176,755 AGranted
Plastic powder coated metal strip
AssigneeArmco Inc.
InventorsSherman E. Winkle, Sr., Lloyd E. Cockerham, Frederick A. Myers
Life of this patent
Estimating the term…
Abstract
Process and apparatus for forming a plastic coating on a metal strip. A metal strip is cleaned, surface treated, coated with an electrostatically charged plastic powder in an enclosed chamber using a plurality of spray guns positioned on both sides of the strip, inductively heated to above the melting point of the powder, and maintained in an infrared heater until the fused powder is flowed into a coating having a smooth surface and a uniform thickness. Thermoplastic and thermosetting coatings, having thicknesses of at least 10 microns formed using total induction and infrared heating times of less than 60 seconds, can be fabricated without cracking.
Claims12
A coating apparatus, comprising:
- means for surface treating metal strip,
- an enclosed coating chamber having an entrance end, an exit end, and a passline for metal strip extending between said ends,
- a plurality of electrostatic spray guns positioned on each side of said passline for coating metal strip with plastic powder,
- one of said spray guns on each side of said passline facing toward said entrance end and another of said spray guns on each side of said passline facing toward said exit end,
- said spray guns inclined at an acute angle relative to the plane of the metal strip when traveling along said passline and generally aligned parallel to the direction of travel of the metal strip when traveling along said passline, an induction coil for heating metal strip to a temperature above the melting point of said plastic powder, and
- means for maintaining said plastic powder above said melting point for sufficient time to form a coating having a smooth surface and a uniform thickness on each surface of metal strip.
3 more elements
A coating apparatus, comprising:
- means for cleaning metal strip of dirt, oil and oxides,
- means for surface treating metal strip,
- an enclosed coating chamber having an entrance end, and exit end, and a horizontal strip passline extending between said ends,
- a plurality of electrostatic spray guns positioned above and below said passline for coating metal strip with plastic powder,
- one of said upper spray guns positioned outside said chamber at said entrance end and another of said upper spray guns positioned outside said chamber at said exit end,
- said spray guns inclined at an acute angle relative to the plane of the metal strip when traveling along said passline and generally aligned parallel to the direction of travel of the metal strip when traveling along said passline,
- an induction coil for heating metal strip to a temperature above the melting point of said plastic powder,
- an infrared heater for maintaining said plastic powder above said melting point for sufficient time to form a coating having a smooth surface and a uniform thickness on each surface of metal strip, and
- means for rapidly cooling said coating.
6 more elements
A coating apparatus, comprising:
- means for prepunching a metal strip into a string of continuous blanks,
- means for surface treating said string of continuous blanks,
- an enclosed coating chamber having an entrance end, and exit end, and a passline for said string of continuous blanks extending between said ends,
- a plurality of electrostatic spray guns positioned on each side of said passline for coating said string of continuous blanks with plastic powder,
- one of said spray guns on each side of said passline facing toward said entrance end and another of said spray guns on each side of said passline facing toward said exit end,
- said spray guns inclined at an acute angle relative to the plane of said string of continuous blanks when traveling along said passline and generally aligned parallel to the direction of travel of said string of continuous blanks when traveling along said passline,
- an induction coil for heating said string of continuous blanks to a temperature above the melting point of said plastic powder,
- means for maintaining said plastic powder for sufficient time above said melting point to form a coating having a smooth surface and a uniform thickness on each surface of said string of continuous blanks, and
- a shear for cutting said string of continuous blanks into cut lengths.
6 more elements
A coating apparatus, comprising:
- means for surface treating metal strip,
- an enclosed coating chamber having an entrance end, an exit end, and a horizontal passline for metal strip extending between said ends,
- a plurality of electrostatic spray guns positioned on each side of said passline for coating metal strip with plastic powder,
- one of said upper spray guns positioned outside said chamber at said entrance end and another of said upper spray guns positioned outside said chamber at said exit end,
- said spray guns inclined at an acute angle relative to the plane of the metal strip when traveling along said passline and generally aligned parallel to the direction of travel of the metal strip when traveling along said passline,
- an induction coil for heating metal strip to a temperature above the melting point of said plastic powder, and
- means for maintaining said plastic powder above said melting point for sufficient time to form a coating having a smooth surface and a uniform thickness on each surface of metal strip.
4 more elements
A coating apparatus, comprising:
- means for surface treating metal strip,
- an enclosed coating chamber having an entrance end, and exit end, and a horizontal passline for metal strip extending between said ends,
- each of said ends including a vestibule extending outside said chamber, a plurality of electrostatic spray guns positioned on each side of said passline for coating metal strip with plastic powder,
- said spray guns above said passline being positioned within said vestibules with one of said upper spray guns being positioned at said entrance end and another of said upper spray guns being positioned at said exit end,
- said spray guns inclined at an acute angle relative to the plane of the metal strip when traveling along said passline and generally aligned parallel to the direction of travel of the metal strip when traveling along said passline,
- an induction coil for heating metal strip to a temperature above the melting point of said plastic powder, and
- means for maintaining said plastic powder above said melting point for sufficient time to form a coating having a smooth surface and a uniform thickness on each surface of metal strip.
4 more elements
Dependencies are inferred from the claim text.