Device for the localized heating of parts of coated metal pipes and of parts of their protective coating
AssigneeAB Tesi
InventorsAusonio Zubiani, Stefano Miotto
Life of this patent
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Abstract
A device (10-10′), (11-11′) for the localized heating of parts of metal pipes (12) connected to each other and of parts of primary plastic coating (16′-18′) of the same pipes, all to be coated with protective material, comprises a spiral-wise development winding consisting of one or more coils (20) and of annular means that are arranged within and coaxially to said coil (20), at the parts of primary plastic coating (16′-18′), and that surround each one of said pipes (12) for heating by induction a zone (14) without primary plastic coating and for indirectly heating, by irradiation, end portions of the same provided with plastic coating (16′-18′) contiguous to said zone (14).
Claims8
A device (10-10′;
- 11-11′) for localized heating a metal tube (12) having a central zone (14) and two sectors (16, 18) located on opposite sides of the central zone and contiguous to said central zone, each of said two sectors (16, 18) being provided with a layer of a primary plastic coating (16′, 18′) and said central zone (14) being without the primary plastic coating, (18′), said heating device comprising a spiral-wise winding having:
- at least one coil (20) having a diameter of said tube and extending along a portion of said central zone of said tube for heating the same by induction heating;
- at least two metal annular elements (22) located inside said winding on opposite sides of said at least one coil (20), respectively, each of said at least two metal annular elements having an inner diameter greater than a diameter of a respective sector coated with the plastic coating and extending along a portion of the respective sector to provide for heating the same by irradiation;
- and
- means for supplying said at least one coil with an alternating current and for controlling flow of the alternating current to said at least one coil.
A method of localized heating a metal tube (12) having a central zone (14) and two sectors (16, 18) located on opposite sides of the central zone and contiguous to said central zone, each of said two sectors (16, 18) being provided with a layer of a plastic coating (16′, 18′), said method comprising the steps of:
- heating a length of said tube (12) comprising a central zone (14) without plastic coating to a first temperature while at the same time heating two sectors (16, 18), each adjacent to said central zone 14 and provided with said plastic coating, to a second temperature lower than said first temperature,
- said first heating being carried out through induction and said second heating being mostly carried out through irradiation heat generated by said first heating.
Dependencies are inferred from the claim text.