Winding – tensioning – or guiding – Wound storage package – Convolute coil
Patent
1998-01-16
1999-07-13
Darling, John P.
Winding, tensioning, or guiding
Wound storage package
Convolute coil
242176, B65H 1828
Patent
active
059214872
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method of winding electric strip without distortion.
Electric strip materials are used, for example for punching from such materials the individual metal sheets of the core packets of power generators, transformers, electromagnets and electric motors. The electric strips consist of a special steel with exactly defined mechanical and electromagnetic properties and, according to Euro-standard 10 106 have to be delivered in a finally annealed condition.
An important electromagnetic property, which has to be assured across the entire length and width of the electric strip, is a low and defined cyclic magnetization loss. In addition, magnetic polarization as well as the mechanical properties are important parameters in terms of materials engineering.
If the cyclic magnetization loss is excessively high, this may lead to undesirable dissipation, for example in the form of heating of the core packets produced from such electric sheet metal. Such heating is substantially based on eddy currents, which are generated with cyclic magnetization in the alternating magnetic field in the core packet. Such eddy current losses are the lowest if the material employed for the electric strip has a defined crystallographic orientation, namely the so-called cube texture. If this cube texture, which is produced in the course of manufacture of the electric strip material, is disturbed, the material loses the required electromagnetic properties at least in the disturbed area.
Even the slightest deformations cause changes in texture in the material and thereby an increase in the displacement density, which is reflected by significantly poorer values of cyclic magnetization. For avoiding such damaging deformations, tensile and bending stresses near the yield point have to be avoided throughout the entire treatment process. For example, the tensile force in the cutting plant has to be kept to a minimum. Likewise, in all direction changes, the bending radius must not be below a critical bending radius leading to permanent bending deformations.
So that the texture of the material produced in the course of manufacture of the electric strip is impaired as little as possible also subsequently when the strip is transported and processed further, it is customary with manufacturers of electric strip material to treat the latter after the heat treatment with as much care as possible and to particularly avoid subjecting the material to high tensile and bending stresses. According to the state of the art, electric strip material is therefore wound into so-called disk coils as carefully as possible and with low strip tension, with the axial width of such disk coils corresponding with the width of the electric strip. Such disk coils are wound in most cases without a winding core; if need be, they may be wound on a winding core having a width conforming to the width of the electric strip.
Said narrow disk-like coils are relatively unstable on account of their special geometric shape especially if a very long section of strip is wound into a coil having a large diameter. This consequently poses the risk that the disk-like coil may be damaged during shipping or further processing, rendering it unusable. By increasing the strip tension during winding a permanent tensile stress is obtained in the electric strip wound into a coil. Such permanent tensile stress enhances the cohesion between the successively wound layers of the coil, which in turn stabilizes the coil. However, such increase in tensile stress is subject to narrow limits because of the risk of changes occurring in the texture of the material. Therefore, relatively short strip sections have to be accepted on each disk in practical life, whether liked or not.
In the course of further processing, the electric strip material is unreeled from said disk-like coil by means of special unwinding equipment and admitted to a punching machine. Due to the limited length of the electric strip section contained in one disk-like coil, such disk-like coils have to be changed relat
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Patent Abstracts of Japan vol. 007, No. 250 (M-254), Nov. 8, 1983 & JPA 58 135067 (Matsushita Denki Sangyo KK), Aug. 11, 1983.
Patent Abstracts of Japan vol. 006, No. 226 (E-141), Nov. 11, 1982 & JPA 57 128013 (Tokyo Denko Kagaku Kogyo KK) Aug. 9, 1982.
C. D. Walzholz Produktions--Gesellschaft mbH
Darling John P.
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