DE2520967A1 - MINERAL INSULATED SHELLED HEATER WITH COLD ZONES - Google Patents

Description

CIiKj ₁ LZ- CJilhh 'j. Mat

Hanau Ge / üz

Mineral insulated jacket heating conductor with cold zones

The invention relates to a mineral-insulated jacket heating conductor with cold zones and a method its manufacture.

For the heating of devices as well as for a wide variety of applications, mineral isolators have proven themselves Jacket heating conductor with cold connection ends proved to be particularly favorable. This is electrical resistance elements for heating purposes, the connections of which by using material with increased electrical conductivity remain cold compared to the actual heating section; there are heating systems axif in the smallest of spaces. Also, due to the large temperature difference between the heating section and cold connection zone a special arrangement for cooling the ends when connecting the jacket heating conductor to the electrical power supply.

There are essentially two known possibilities, jacket heating conductors with cold connection ends, that is to say with Areas of increased electrical conductivity,

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place. Either the cold connection ends are realized with a larger cross-section of the heating conductor, by tapering the heating sections by mechanical methods or by going on one at the connection ends Material with increased conductivity, e.g. copper, over, allow this material to be dimensioned appropriately there is a wide range of weaknesses in performance and thus achieve different temperatures between the heating sections and the cold connection ends.

For example, from the PHILIPS company publication "Mantel-Heizleiter ", Edition 1974-1 known, jacket heating conductor with produce cold ends by combining a heating part with one or two supply line parts, the heating part from a central heating conductor wire and the lead part from a central core made of a copper alloy consists. Both parts are insulated and placed in a metallic jacket.

Disadvantageously, however, both manufacturing processes can be used Execute only through extensive individual production of the heating conductor pieces, whereby relatively complex work steps have to be used. That makes the adjustment even more difficult of prefabricated items according to the last-mentioned process add that great demands on

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the tolerance of the outer diameter at the transition from the heating to the supply part must be set, to ensure an even connection. There is also the risk of this connection breaking through a coarsely crystalline transformation of the heating conductor alloy, e.g. through the welding together of the two Parts can occur cannot be completely ruled out.

While avoiding the disadvantages of previous solutions, the object of the invention is to provide a mineral-insulated Specify jacket heating conductor of the type mentioned, which is economical together with the cold zones can be manufactured in one operation.

To solve this problem, it is proposed according to the invention that the heating conductor material at least in the areas to enclose the connection ends with a material of increased electrical conductivity.

It has proven to be particularly advantageous to use copper, nickel, iron or their alloys as a material electrical conductivity to use.

Such a mineral-insulated jacket heating conductor is expediently produced by adding a heating conductor wire or tape at specified intervals with a material

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increased electrical conductivity encased and insulated is inserted into a jacket tube and that this arrangement is reduced to the desired cross section and by separating in the areas of increased electrical conductivity into individual mineral-insulated jacket heating conductor pieces is divided.

The advantages that can be achieved with the invention exist especially in a simplification of the production, which makes it possible to use mineral-insulated jacket heating conductors produce cold connection ends continuously in one operation.

It is also possible according to the invention to determine the position and length of the cold zones and ler heating sections in the mineral-insulated Sheath heating conductor to be defined as desired. To be highlighted is also that the cold zones have the same outside diameter as the heating sections, which is has a particularly advantageous effect in various applications, e.g. when wrapping objects to be heated. Because the heating conductor is not interrupted even in the cold zones, but is reinforced by the cover the cold zones have at least the same mechanical strength as the heating sections.

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An embodiment of the subject matter according to the invention is shown schematically in the drawing in longitudinal section and is described in more detail below:

The figure here shows a mineral-insulated jacket heating conductor manufactured according to the invention with cold Zones, with 1 the copper tubes pushed onto the heating conductor wire 2, with 3 the jacket tube and 4 denotes the electrical insulation material.

To produce this jacket heating conductor, a heating conductor wire 2 made of Ni-Jr 60/20 with a diameter of 4 mm at intervals of 500 mm Tubes 1 made of copper of 100 mm length, 1 mm wall thickness and 6.1 mm outside diameter pushed on and fixed. The heating conductor was then placed in a rust-proof and corrosion-resistant jacket tube 3 with an outer diameter of approx. 20 mm used and with a high temperature resistant Powder of magnesium oxide 4 insulated from the jacket tube 3. The reduction in the cross-section of this arrangement to the desired outside diameter of 3 now took place then in a known manner by rolling and drawing with the appropriate intermediate anneals.

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May 9, 1975 Ge / Bz.

The mineral-insulated one was used to mark the cold zones Mante! Heating conductor loaded with a current of approx. 12 A, which leads to a visible glowing of the heating section led. The continuous sequence of heating sections and cold zones was isolated into individual mineral ones Jacket heaters with cold connection ends divided. When determining the electrical properties, a Resistance of 3.3 Ohm / m, while the cold connection ends had a resistance of only 0.05 Ohm / m. The temperature of the cold zones reached a maximum of 4-0 G at a temperature of the heating section of approx. 800 G.

The mineral-insulated jacket heating conductor according to the invention with cold zones is not necessarily limited to the embodiment. For special applications can be produced as a further design, e.g. oval cross-sections.

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Claims (3)

VACUUMSCHMELZE GMBH · May 7th - 9th, 1997; Hanau 3-e / Bz. Patent claims 1. \ Mineral insulated jacket heating conductor with cold zones, characterized in that the heating conductor material at least in the areas of the connection ends with is encased in a material of increased electrical conductivity. 2. Mineral insulated jacket heating conductor according to claim .1, characterized in that the material of increased electrical conductivity is copper, nickel, iron or whose alloys are used. 3. Process for the production of a mineral-insulated sheathed heating conductor according to claim 1 or 2, characterized in that that a heat conductor wire or - "band in a given; Distances covered with a material of increased electrical conductivity and insulated in a jacket tube is used and that this arrangement is reduced to the desired cross-section and separated into the areas of increased electrical conductivity divided into individual mineral-insulated sheathed heat conductor pieces will. 0 9 8 4 7/0556 Lee? Side