Source: https://patents.google.com/patent/US4532398
Timestamp: 2018-02-18 11:16:19
Document Index: 29526876

Matched Legal Cases: ['art 2', 'art 2', 'art 2', 'art 5', 'art 5', 'art.\n15']

US4532398A - Induction coil - Google Patents
US4532398A
US4532398A US06446050 US44605082A US4532398A US 4532398 A US4532398 A US 4532398A US 06446050 US06446050 US 06446050 US 44605082 A US44605082 A US 44605082A US 4532398 A US4532398 A US 4532398A
US06446050
An induction coil, preferably for an induction heater, comprises a working coil, an outer casing and an inner lead-through channel for the workpieces, such as rods or tubes, which are to be treated in the induction coil. The region of the outer casing closest to the working coil consists of a layer of a rubber-elastic compound outside which is arranged a concrete casing. Using a two-part outer casing of this kind avoids the use of asbestos which is increasingly suspect because of its health hazard.
The present invention relates to an induction coil, preferably for an induction heater, comprising a working coil of electrically conducting material, an outer casing surrounding the working coil and an inner lead-through channel within the working coil for workpieces, such as rods or tubes, which are to be treated (e.g. heated) in the induction coil.
It is known to surround the working coils of many types of induction heaters with a layer of an asbestos-containing material for heat insulation and electrical insulation of the working coil. The use of asbestos is disadvantageous because of the health risks associated therewith and the obtaining of a staisfactory asbestos-free replacement material for the outer casing of an induction coil poses problems.
The invention seeks to provide a solution to the above-mentioned problem and other problems associated therewith.
FIG. 1 shows a hollow metallic helical induction coil 1 embedded in a two-part casing, the inner part 2 of which is formed from a rubber-elastic compound, suitably a temperature-resistant silicone rubber, which can withstand a temperature of about 200° C. The inner casing part 2, since it is made of a castable material, can be applied in a fluid condition around the working coil 1 and allowed to harden in situ. Surrounding the flexible casing part 2, an outer casing part 5 of concrete is provided, suitably refractory concrete, which is preferably glass fiber reinforced. The outer part 5 provides the necessary mechanically strong support for the working coil, and the complete casing 2, 5 also provides a good thermal shield and good electrical insulation for the working coil. The rubber-elastic layer 2 damps out and distributes the electromagnetic forces, which are generated by the working coil 1, and absorbs the forces arising because of changes in dimensions of the working coil due to its thermal expansion. In addition, the flexible inner layer 2 has good noise- and vibration-damping properties. Silicone rubber is particularly suitable since it has very good electrical insulation properties. Without the layer 2 of rubber-elastic material there would be a risk of the forces generated by the coil 1, during use, bursting the more rigid outer refractory concrete layer 5.
The concrete mass can be a concrete as used in the construction industry or a refractory concrete. The resilient layer surrounding the working coil can be a silicone rubber capable of withstanding a temperature of 250° C. An air-hardening material applied in fluid state is preferred.
1. An induction coil comprising an electrically conducting working coil, an outer casing for the coil and a lead-through channel disposed within the working coil for workpieces which are to be treated therein, the outer casing comprising at least one compressible hollow body of a temperature-resistant silicone rubber, capable of withstanding temperature of about 200 degrees C., adjacent to the working coil and a mass of concrete over said hollow body.
14. An induction coil comprising a helix of electrically conducting tubular material, a refractory electrically insulating tube disposed within the helix to define a through-channel for elements to be treated within the coil and an electrically insulating casing surrounding the helix, the casing being in two parts,
an inner part of at least one compressible hollow body of temperature resistant silicone rubber, capable of withstanding temperature of about 200 degrees C., about the helix, and
an outer part of a refractory asbestos-free set hydraulic cementitious mixture over the inner part.
15. A coil as claimed in claim 14, in which the inner part includes a layer formed by casting a hardenable fluid silicone around the helix.
US06446050 1981-12-04 1982-12-01 Induction coil Expired - Fee Related US4532398A (en)
SE8107289 1981-12-04
US4532398A true US4532398A (en) 1985-07-30
ID=20345209
US06446050 Expired - Fee Related US4532398A (en) 1981-12-04 1982-12-01 Induction coil
US (1) US4532398A (en)
JP (1) JPS58103797A (en)
CA (1) CA1192267A (en)
DE (1) DE3243392A1 (en)
FR (1) FR2517920B1 (en)
GB (1) GB2113510B (en)
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FR2205719B3 (en) * 1972-11-03 1975-11-28 Stel
Preventative Disclosure No. 13/60 (Industrial Teknik 10, 1960). *
FR2517920A1 (en) 1983-06-10 application
CA1192267A (en) 1985-08-20 grant
FR2517920B1 (en) 1986-09-26 grant
GB2113510A (en) 1983-08-03 application
JPS58103797A (en) 1983-06-20 application
CA1192267A1 (en) grant
DE3243392A1 (en) 1983-06-09 application
GB2113510B (en) 1985-05-22 grant
JP2002087826A (en) 2002-03-27 Tube apparatus for vacuum clarification
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US4314144A (en) 1982-02-02 Thermostat mounting arrangement for electric heating appliance
US4566495A (en) 1986-01-28 Concentric walled conduit for a tubular conduit string
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