JPH0559182B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a ring transformer for energizing and heating a running band in a device that energizes and heats a running band to a predetermined temperature for various purposes. The present invention relates to a versatile ring transformer for electrically heating a band material that can be heated uniformly or unevenly. (Prior art) One of the joint applicants of this application created an electrical heating device for running materials based on a new technical concept, and the invention directed to wire rods was published in Japanese Patent Application No. 61-272798 (Japanese Unexamined Patent Publication No. 272798). No. 63-128125), and the invention directed to the band material was filed in Japanese Patent Application No. 62-300127. The inventions of both applications will be described with reference to FIGS. 1a and 1b showing a device for handling a strip material, for example, a transformer 10 in which the feed passage L passes through the inside of the ring of the annular iron core 11, and a transformer 10 that is close to both ends of the transformer 10. Roll electrodes 21 and 22 made up of, for example, a pair of rolls a and b are placed and in contact with the strip material W on the feed path, and the two roll electrodes 21 and 22 are electrically connected via, for example, a slider S. The resistance R1 of the running heated belt material W, which is composed of the conductive materials 3 and 3 and is between the roll electrodes 21 and 22, and the resistance R2 of the conductive materials 3 and 3.
Set the relationship between R1>>R2 and transformer 10
The purpose of energization is to heat the belt material W running between the two roll electrodes 21 and 22 by inducing a secondary current with the conductive materials 3 and 3 as return wires by supplying power to the primary winding 12. It is a heating device. (Problems existing in the prior art) By the way, the current heating device 100 does not cause any problems when heating a wire rod.
When heating a strip material, the problem of how to uniformly heat it in the width direction has arisen. Furthermore, even if a certain configuration is used to obtain uniform heating, the size range of the strip material that provides uniform heating is limited, and if the material of the strip material is different, even if the dimensions are the same, uniform heating may not be obtained. Therefore, it has been pointed out that it is necessary to prepare a large number of transformers corresponding to strips of different materials and sizes, leading to an increase in equipment costs. Furthermore, if the device is configured to uniformly heat the strip material, if necessary, for example, if you want to heat the edge portion to a slightly higher temperature than the center portion, or actively want to heat unevenly in the width direction, It was also discovered that there were some built-in problems that were difficult to deal with, and countermeasures were sought. (Purpose of the Invention) The present invention has been made to solve the above-mentioned problems of the invention of the device for energizing heating of strip material, which is the invention of Japanese Patent Application No. 62-300127. Accordingly, it is an object of the present invention to provide a versatile ring transformer for electrically heating a band material, which can uniformly heat the width direction or obtain desired non-uniform heating. (Structure of the Invention) The gist of the present invention is to wind the primary winding of the transformer multiple times over almost the entire length in the width direction of the iron core, provide taps at a plurality of predetermined positions on the winding, and wind the primary winding through the taps. A ring transformer for energizing a heating band is characterized in that the range of power feeding to the wire can be controlled in accordance with the material, width and thickness of the heating band. (Example) The present invention will be described in detail below with reference to FIG. As shown in the figure, a primary winding 12 is wound around the core 11 of the transformer 10 in multiple turns over almost the entire length in the width direction. In the primary winding 12, taps indicated as T are provided at a plurality of predetermined positions of the winding, such as a to n. Therefore, for example, tap Tg
and Th are closed, and the others are open, and if power is supplied to the primary winding 12 from the power supply shown as E, the power supply current flows only to the winding located between taps Tg and Th, and taps Te and Ti are closed. , and other open states, the power supply current will be the same as the tap Te/Ti.
If power is supplied with the taps Ta and Tn closed and the others open, the supplied current will flow through the entire length of the primary winding 12. In this way, the transformer configuration of the present invention is
It is possible to control the range of power supply to the primary winding 12, such as by limiting the power supply current to the primary winding 12 to a predetermined range, or by supplying power over the entire length. (Function of the Invention) The present invention heats each strip material uniformly in the width direction by controlling the power supply range to the primary winding in a predetermined manner corresponding to each of various strip materials having different materials, widths, and plate thicknesses. , or has the effect of enabling desired non-uniform heating. (Progress until completion of the invention) The present invention was completed through current density analysis during electrical heating, heat conduction analysis, and experiments using an actual machine. (1) Current density analysis during current heating: The belt material W to be heated by the transformer 10 during current heating
The current density distribution induced by the width of the strip W (Ww),
A computer using the finite element method was used to analyze changes in relation to the plate thickness t and the winding width (Cw) of the primary winding 12. Some of them are disclosed below. Basic formula of electromagnetic equation rot(1/μrot〓)=〓o−σ∂〓/〓t−σgradφ…
...(1) In the above equation (1), if it is assumed that the x-y two-dimensional field is isotropic and that 〓 changes sinusoidally, then equation (1) becomes as follows. 1/μ(∂ ² Az/∂x ² +∂ ² Az/∂y ² )=−Jo+jωσAz
+σgradφ ...(2) However, 〓: Magnetic vector potential (wb/m) Az: Z-direction component of magnetic vector potential
(wb/m) 〓o: Forced current density (A/m ² ) Joz: Z-direction component of forced current density (A/m ² ) μ: Magnetic permeability (H/m) σ: Electrical conductivity (υ/m) ω: Angular frequency (rad/s) φ: Potential (V) A Using the above formula (2), the common analysis conditions and physical property values are as follows, and for example, taking a steel strip that is a common material to be heated, Changes in the conductivity σs of the strip material and the width of the strip material when the strip width (Ww) and the winding width of the primary winding (Cw) are in the relationship (Ww=Cw) for a strip material with a plate thickness of 2 mm. The correlation between the change in the directional surface current density J distribution was determined. f = 60 (Hz) μc = 6000 (relative magnetic permeability of iron core) μw = 1 (relative magnetic permeability of primary winding) μs = 30 (relative magnetic permeability of strip material) σs = (conductivity of strip material); 20℃ ……7.7×10 ⁶ 200℃……4.0×10 ⁶ 750℃……1.0×10 ⁶ However, the gap between the primary winding and the strip g = 150 (mm) Also, the primary winding current Joz is The average current density was set to 1.5×10 ⁶ (A/m ² ). Figure 3 shows the analysis results when there is a relationship of (Ww = Cw), a is a magnetic flux simulation diagram, and b is a current density J distribution diagram of the strip material corresponding to the above change in the strip material conductivity σs, Line A in the figure is 7.7×10 ⁶ , line B is 4.0×10 ⁶ , and line C is
In the case of 1.0×10 ⁶ , it shows that the current density J becomes uniformly distributed as the temperature rises. In addition, the current density deviation (edge
-center/center) are summarized in Table 1.

【table】

Claims (1)

[Claims] 1. A transformer in which a feed passage passes through the ring of the annular iron core, roll electrodes arranged close to both ends of the transformer and in contact with the strip material on the feed passage, and a conductor that electrically connects the two roll electrodes. In the transformer of the heating device, the primary The winding is wound multiple times over almost the entire length in the width direction of the iron core, and taps are provided at a plurality of predetermined positions on the winding, and the power supply range to the primary winding through the taps is determined by the material of the heating band material, the width, and the like. A ring transformer for energizing heating of a band material, characterized by being configured to be controllable according to the thickness of the plate.