DE507556C - High frequency induction furnace - Google Patents

Description

GERMAN EMPIRE

ISSUED ON SEPTEMBER 18, 1930

REICH PATENT OFFICE

PATENT LETTERING

M 507556 CLASS 21h GROUP

Siemens & Halske Akt-Ges. in Berlin-Siemensstadt *)

High-frequency induction furnace Patented in the German Empire on June 11, 1927

The invention relates to an arrangement of the primary winding for high frequency induction furnaces. So far, water-cooled copper pipes or relatively strong copper strips have been used as such. With such windings, however, the influence of the skin effect becomes unpleasantly noticeable in that the currents are compressed on the inside of the conductors, so that most of the conductor cross-section is not used for conducting current and the efficiency of the furnace is relatively poor For example, when melting metals, the conductivity of iron, for example, has not yet succeeded in increasing it to over 70 "J _0. It would be even worse if several turns were used instead of one layer.

According to the invention, this disadvantage is avoided in that the primary winding in is divided into two or more flat-wound tapes isolated from one another, with first the thickness of the individual bands is such that the effect of the skin effect is not noticeable and the cross-section for the power line is fully utilized, and secondly, the individual turns are arranged and designed so that they, with regard to resistance, Impedance and inducing effect on the furnace insert are equal to one another.

In the figures, several exemplary embodiments of the subject matter of the invention are shown with strips arranged in multiple layers. Fig. 1 shows in vertical section a crucible t, around which a conductor of a special kind is wound like a screw ". This conductor can according to Figs show on a significantly reduced scale, consist of two, three or four layers of thin copper tape.

chooses that value

\ r

= is not exceeded, where σ is the conductivity in absolute units and ν is the number of periods. The cross section for the power line is thus fully utilized; the width corresponds to the amperage to be used in each case for the furnace. The thickness is proportional to the square root of the frequency, so that at a frequency of 10,000 it would only be ¹ Z _{10 of} the conductor thickness at a frequency of 100. For these values of the frequency, thicknesses of 0.67 and 6.7 mm would result.

The copper strips a, b or a, b, c or a, b, c, d forming the conductor are connected in parallel by being united at the ends to form the power connections s _v s _s. They are isolated from each other along their length,

") The patent seeker stated as the inventor:

Wilhelm Esmctrch in Berlin-Halensee,

for example by a coating with enamel; also can be arranged more appropriately Air insulation spacers can be provided. Finally, between the Tapes can also be inserted strips of insulating material.

The bands are arranged so as to be interlaced with one another at one or more points in such a way that they all occupy different positions in the same way over their length. According to Fig. 2, a twist point A _{1 is} provided for the bands α and b , and each of them is on one half of its length on the inside and the other half on the outside. According to Fig. 3, three conductors a, b, c are provided, the length of which is interchanged at two inclination points s " in such a way that each conductor is ¹ Z _{8 of} its length on the inside, in the middle and on the outside of the Overall conductor lies. According to Fig. 4, four conductors a, b, c, d are finally used, the position of which is reversed in three twisting points S _{3 in} such a way that each band occupies a different position in the overall _{conductor over * / 4 of the total length.} With this set arrangement, all parts of the individual bands are connected in series, and the current therefore flows in the same way in all layers of the overall cross-section.

In Fig. 5, an embodiment for the twist S ₁ according to Fig. 2 is shown. The conductor strip b ' lying at the front left is folded vertically upwards by an edge k lying at 45 °. The connecting piece ν formed in this way is curved backwards and downwards again and then again folded over at an angle, so that the conductor part b continues at the same height, but in a position parallel to V. The band a lying behind b ' in the plane of b is bent at points c and d in such a way that it lies parallel to itself in the plane of V.

Instead of the minimum number of entanglement points given in Figs. 2 to 4 a larger number of these can also be used. The number of individual conductor strips are still increased. After all, it is enough for some purposes also the use of a single tape, if this is in a corresponding number of layers is wound in the manner of a coil and has the indicated cross section, the which has the highest utilization with regard to the skin effect for the passage of the current.

In Figs. 6 and 7 a further embodiment is shown in which all the individual conductors are connected in series. Fig. 6 shows a crucible-like hearth t with a slightly conical cross-section around which ribbon-shaped conductors are wrapped in three turns or rings I, II, III of three layers e, f, g each. The individual Bandwiudüngen are between the supply lines S ₁ , s _v as indicated in Fig. 6, connected one behind the other in such a way that the current in the uppermost ring I the outer conductor e, in the following ring II the central conductor f and in the third ring III flows through the inner conductor g. From this it then reaches the center conductor f and so on until it finally leaves the outer winding layer c again in the lower turn III through the connection line S _2.

In Fig. 7 the connections of the individual turns are shown on an enlarged scale. These are again made by folding over the conduction bands twice, which at the transition points u hereby on the one hand get into another ring, on the other hand also into another plane, while at the connection points ν on the outside of the top and bottom rings I and III there is only one transition takes place in a different winding position.

The arrangements shown enable the efficiency of the high-frequency furnace to about 90 to 95 per cent, unless the appropriate one is chosen Cross-section, the arrangement is also made for crucibles that are not purely cylindrical, that ohmic resistance and impedance and at the same time also the inducing effect on the oven insert are the same everywhere.

For a finer compensation of the current flow when acting on the secondary circuit To obtain, any parallel and series connections of the strip-shaped individual conductors can be made with simultaneous Using the arrangement according to Figs. 2 to 4 and Fig. 6 can be carried out.

Claims (5)

Patent claims: i. High-frequency induction furnace whose primary winding is made of flat-wound insulated Ribbons consists, characterized in that this winding in two or several strips isolated from one another, so thin that the effect of the Skin effect can be neglected, is divided, which are arranged so that all individual windings are equal to one another with regard to resistance, impedance and inducing effect on the furnace insert are. 2. High-frequency induction furnace according to claim 1, characterized in that the individual conductors of the primary winding are connected in such a way that their different Share all possible positions in the radial direction against the included one Take part. 3. High-frequency induction furnace according to claim 2, characterized in that the primary conductor, optionally arranged in a plurality of turns, consists of a number of parallel-connected bands which are interlaced against each other at at least one point in such a way that each band is one after the other, namely the inner one , middle, outer etc. position (Fig. 2 to 4). 4. High-frequency induction furnace according to claim 2, characterized in that the primary conductor consists of a plurality of rings consisting of several individual conductors is formed and all the individual conductors are connected in series that the Current flows through different layers one after the other in the different rings (Fig. 6). 5. The high-frequency induction furnace according to claim 1 or the sub-claims, characterized in that the band-shaped individual conductors are guided by folding by 90 ⁰ and appropriate bending in a different plane parallel or simultaneously in a different height position (Fig. 5 and 7). 1 sheet of drawings Gtonra; r in «i.:n