US2677538A - Method and apparatus for preventing piled sheet iron from sintering together during annealing - Google Patents

Description

May 4, 1954 J. BLAUs ET AL K 51m w ra w Imsm# nu@ H @a VZ@ A@ c@ S/J md, a/Y JIT@ Patented May 4, 1954 METHOD AND APPARATUS FOR PREVENT- ING PILED SHEET IRON FROM SINTERING TOGETHER DURING ANNEALING v Janis Blaus, Vasteras, and Willy Olsen, Ludvika,

Sweden, assignors to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a Swedish corporation Application November 8, 1951, Serial No. 255,498

Claims priority, application Sweden November 9, 1950 6 Claims. l

In the conventional annealing process of piled sheet iron material such as core iron within a furnace under high temperature with or without protecting atmosphere, the sheets sinter together at a certain temperature depending on the character of the material and the atmosphere, i. e. the crystals in one sheet grow and grow together with crystals in the adjacent sheet. Beyond a certain annealing temperature, the sintering spots do not bring about a fixed connection, but this occurs after the temperature of the sheets in the pile has decreased to a certain value whereat the sinter bridges were able to stiften. Due to this phenomenon, it is in many cases difficult or impossible to remove the individual sheets after annealing. In order to avoid this sintering process, the sheet surfaces are coated with a thin layer of refractory material for preventing the sheets from making metallic contact with one another during the annealing process. But also sheets treated in this manner tend to sinter together on the margin. Besides this drawback, that the removement of the sheets after annealing is difcult, the sintering of the margins of the sheets has the result that the protecting atmosphere is not able to intrude between the sheets and to extrude the gases still existing therein.

According to the present invention, these drawbacks are overcome for piled sheet material without or with protecting means against sintering by imparting to the pile of sheets a bending movement during the annealing process, so that the sheets are displaced with respect to one another. By this method the sheets are prevented from sintering together or, should sintering bridges have been produced during the annealing process, they will be prevented from stffening.

The invention will be described with reference to the accompanying drawing showing a sectional elevation view of a furnace accommodating a pile of sheets. The gure illustrates an example of a construction for carrying out the method according to the invention. Designated by l is the pile of sheets, by 2 a support divided into two parts, and by 3 members adapted to be raised and lowered. The annealing furnace is designated by 1i. When the members 3 are raised and lowered, the outer ends of the subdivided support 2 are raised and lowered causing the pile of sheets l to be subjected to repeated bendings, whereby the surfaces of the sheets are displaced with respect to one another. According to the new method, the connection between the sheets, produced by the sintering phenomenon, is destroyed by the repeated bending of the pile of sheets, and thus the individual sheets may be removed without any diiiculty after the annealing process. It is clear that this bending tprocess may be limited to the interval between the production of sinter spots and the stiffening of the same.

Instead of raising and lowering the outer ends of the support, it is also possible to raise and lower the middle portion of the support. Furthermore, a hoisting means seizing the middle portion of the pile of sheets from below and raising and lowering the pile one or several times may be employed.

We claim as our invention:

1. A method of annealing iron sheets, which comprises piling iron sheets substantially hori- Zontally upon each other in a furnace, annealing the iron sheets, and bending the pile of sheets in the furnace to cause the edges of adjacent sheets to be displaced with respect to each other to prevent the sheets from sintering together.

2. A method according to claim 1, in which the bending motion is repeatedly applied to the pile.

3. In a furnace for annealing iron sheets, means for preventing the sheets from sintering together, comprising a substantially horizontal base plate divided into two adjacent parts for supporting a pile of substantially horizontally disposed iron sheets for annealing, and mechanical means for inclining the parts of the base plate with respect to each other to displace the adjacent edges of the supported sheets with respect to each other.

4. Means according to claim 3, in which the said mechanical means are applied to the outer edges of said adjacent parts of the base plate for raising and lowering the outer end portions of said parts.

5. In a furnace for annealing iron sheets, means for preventing the sheets from sintering together, comprising means for repeatedly raising and lowering the middle zone of the pile of sheets to displace with respect to each other the edges of adjacent plates to prevent the sheets from sintering together.

6. A method of annealing iron sheets, which comprises piling the sheets substantially horizontally upon each other in a furnace, annealing the piled sheets, and preventing the sheets from sintering together by changing the height of the central portion of the pile of sheets with respect to the two end portions of said pile to cause relative displacement of each sheet in said pile with respect to each sheet adjacent thereto.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,046,933 Allis Dec. 10, 1912 1,405,762 Curtis Feb. '7, 1922 1,738,680 p Wineman Dec. 10, 1929 1,745,403 Caugherty Feb. 4, 1930 2,626,430 Dawson Jan. 27 1953

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