A heating device for calender cylinders, comprising a core cylinder arranged coaxially in a cylinder adapted to support a plurality of heating elements; the core cylinder and the cylinder adapted to support the heating elements are configured to be accommodated in a fixed manner within a rotating calender cylinder; the core cylinder has an inlet for the passage of air which is adapted to make air flow and gather inside the core cylinder.

A sheet manufacturing apparatus has a heating/compressing unit configured to form a sheet by heating and compressing material including fiber and resin, and the heating/compressing unit includes a first rotating body that rotates, and a second rotating body that rotates in contact with the first rotating body. The sheet manufacturing apparatus holds, heats, and compresses material by the first rotating body and the second rotating body. The sheet manufacturing apparatus includes a heating unit that heats the outside surface of at least one of the first rotating body and second rotating body.

The present invention for eliminating a need for a temperature detecting element adapted to measure the temperature of a roll main body provides an induction heated roll apparatus including: a roll main body; a magnetic flux generating mechanism including an iron core and a winding; and a power supply circuit provided with a control element adapted to control AC current or AC voltage. The apparatus calculates the temperature of the roll main body using an AC current value obtained by an AC current detecting part, an AC voltage value obtained by an AC voltage detecting part, a power factor obtained by a power factor detecting part, a winding resistance value of the winding, and an excitation resistance obtained from characteristics of a relationship between a magnetic flux density and an excitation resistance of a magnetic circuit including the iron core and the roll main body as parameters.

A sheet manufacturing apparatus having a compactly configurable heating/compressing unit that heats and compresses material efficiently.

A sheet manufacturing apparatus having a heating/compressing unit configured to form a sheet by heating and compressing material including fiber and resin, the heating/compressing unit including a first rotating body that rotates, and a second rotating body that rotates in contact with the first rotating body, and holding, heating, and compressing material by the first rotating body and the second rotating body; and the sheet manufacturing apparatus including a heating unit that heats the outside surface of at least one of the first rotating body and second rotating body.

The invention relates to a heating device for heating a roller, wherein the heating device has a heating element which is configured to be inserted into a bore of the roller and to provide, preferably to provide electrically, heating power and/or heat for heating the roller and/or a roller body of the roller, and wherein the heating device has a clamping set which is arranged on a surface of the heating element and which is configured to contact an inner surface of the bore when the heating device is inserted into the bore of the roller and to transfer heat from the heating element conductively to the roller and/or the roller body. The invention furthermore relates to a roller. The invention furthermore relates to a calender or an embossing cassette.