| 摘要 |
Inductors for heating rolls especially of the type used in rolling mills for sheet materials such as paper, textiles, plastics and the like, are configured to enhance and concentrate eddy currents in areas along the length of the roll to selectively heat the roll as desired and control moisture and caliper properties of the sheet. The inductors have cores with a center leg around which the exciting coil is wound and an outer leg surrounding the coil and connected at one end to the inner leg. These inductors or electromagnets are mounted immediately adjacent a roll of magnetic flux conducting material, such as iron or steel, to heat the roll surface as desired across the length of the roll as it is rotated through the concentrated electromagnetic field generated by the inductor. The magnetic field or flux is concentrated in an annular zone and passes between the nested inner and outer legs of the core through the roll without travelling through a wide air gap and the desired roll temperatures are achieved with minimum current input to the coil. The air gap may be varied in the cross machine direction and the excitation of the inductors may be varied to induce or compensate for temperature variations across the roll.
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