US1980011A

US1980011A - Method for the production of magnetic strips or tapes

Info

Publication number: US1980011A
Application number: US684771A
Authority: US
Inventors: Sprung Helmut
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1932-08-16
Filing date: 1933-08-11
Publication date: 1934-11-06
Anticipated expiration: 1951-11-06

Description

H SPRUNG METHOD FOR THE PRODUCTION OF MAGNETIC STRIPS OR TAPES Nov. 6, 1934.

Filed Aug. 11, 1953 /N [/5 N TOR H. SPRUNG A TTORNE V Patented Nov. 6, 1934i- METHOD FOR THE PRODUCTION OF MAGNETIC STRIPS OR TAPES 4 Helmut Sprung, Berlin oberschoneweide, Germany, assignor to General Electric Company, Schenectady, N. Y., a corporation of New York Application August 11, 1933, Serial No. 684,771

In Germany August 16, 1932 6 Claims. (Cl. 175-21) It has previously been proposed to produce sheet metal, wire, and strip cores and Krarup windings which are made of a ferromagnetic material which after any desired saturation with direct current field, has an instability of less than with an initialpermeability of w= andmore. In the production of strip cores it has been found that when the strip is simply wound up, the elastic stresses set up in it, lead to an appreciable deterioration of the magnetic properties, particularly the hysteresis. On this account it has been proposed in the case of strip cores to obtain the requisite bending by plastic deformation either by bending the strip at regular intervals or by first winding the strip on a very much thinner mandrel and subsequently allowing it to expand to the desired diameter. The first process is accompanied by the disadvantage that the core no longer possesses a circular shape and can therefore only be wound with an uneconomical'utilization of the available space; the second process possesses the disadvantage that the core after expanding can no longer be wound so tightly.

The object of the invention is to provide a process for the production of strip-cores in which these disadvantages are eliminated by plastically deforming the strip of ferromagnetic material a number of times in different directions before it is wound into a core so that it loses its springiness to an appreciable extent and it is then given a final change of shape such that it does not exhibit any further elastic tension after being wound up. For this purpose the plastic deformation and winding may advantageously be carried out in one working process. The repeated plastic deformation may be done in various ways. One process which has been found particularly suitable is that in which the strip is drawn between two rows of rollers which are set with repect to one another in such a way that the rollers in one row stand opposite the gaps in the other row and engage in these gaps. The diameter of the rollers in one row is preferably selected somewhat greater than the diameter of the rollers in the other row.

A diagram of one apparatus suitable for the production of strip cores according to the invention is illustrated in the drawing by way of example.

In the drawing the strip 1 is wound into a core 3 on the mandrel 2. The mandrel may be driven in any desired manner, for example, by means of gear wheels 4 and 5. Before being wound up, the strip is plastically deformed a number of times in oppositedirections according to the invention by drawing it between the rollers 6 and '7 which may consist of steel, for example. The

rollers are arranged in such a way that the rollers 'Z, the diameters .of which are the smaller, are always opposite the gaps in the rollers 6. The distance apart of the two rows of rollers may be altered by means of the pressure screw 8, according to the nature and composition of the material employed. The smaller the distance between the two rows of rollers is, or the more the rollers having the smaller diameter project into the gaps between the rollers having the larger diameter, the greater will be the plastic deformation. On leaving the rollers the strip will have a permanent bend on the side of the smaller rollers. This bend must be of such size that the strip on being wound up will possess little or no elastic tension. The size of the bend will depend upon the diameter. of the rollers and their mutual position with respect to one another and also upon the tensile stress during the drawing operation, as the bend may be partially neutralized by the tensile stress. In accordance with the diameter of the core to be wound, therefore, the separate factors must be adjusted in such a way that the bend has the requisite size. Furthermore, precautions must, of course, be taken that the strip receives its permanent bend in the direction in which it is subsequently to be bent as a core.

The above described method of production possesses the further advantage that any rough edge or ridge formed by cutting the strips is pressed flat by the rollers so that a special flattening process is rendered unnecessary.

The insulation of the strip. core is carried out in a known manner. Since the core will have no further spring expansion after being wound. it is possible to allow athin paper strip to run in with it, very little danger existing of the paper strip tearing, which was often the case in the hitherto customary process. Moreover, insulation may also be applied by impregnating the strip before or after winding in any liquid or easily readily flowing insulating medium, such as lacquer or like insulating mediums. and further in isinglass or similar materials and generally in' all insulating mediums which are employed for solid cores.

i What is claimed is:

up, so that it loses its spring power to an appre- 4. Process according to claim 1, characterized by that for purposes of insulation a thin paper strip is wound up parallel with the strip itself.

5 Process according to claim 1, characterized in that the strip is impregnated in a liquid or readily flowing insulating medium before or after winding.

6. Process according to claim 1, characterized in that the strip is insulated by chemical treatment of the surface.

HELMUT SPRUNG.