US3294598A - Method of annealing strip in coils - Google Patents

Description

Dec. 27, 1966 D. o. NORRIS 3,294,598

METHOD OF ANNEALING STRIP IN COILS Filed April 21: 1964 INVENTOR. DONALD 0. NORRIS A r tarney United States Patent 3,294,598 METHQD 0F ANNEALING STRIP IN CiIILS Donald 0. Norris, Rocky River, Ohio, assignor to United States Steel (Iorporation, a corporation of Delaware Filed Apr. 21, 1964, Ser. No. 361,333 4 Claims. (Cl. 148-134) This invention relates to a method of annealing cold rolled steel strip in coils. As used herein, the term strip is not limited to material of any particular Width, and includes material sometimes referred to as sheet.

Conventional practice in bell or box-annealing steel strip is to heat coils of the strip to temperatures of at least 1000 F. in an annealing furnace which contains a suitable non-oxidizing atmosphere. When coils of cold-rolled strip are annealed in this manner, fine longitudinal scratches often appear on the surface of the strip. Such scratches may remain visible even after the strip as been temper rolled, formed into a final product and plated. The scratches probably are caused by relative longitudinal movement of the coil convolutions as the coil is heated. A coil does not heat uniformly, but heats first from the more exposed portions at the outside and next to the core. Hence, the more exposed convolutions expand before the others and loosen to produce relative movement.

An object of my invention is to provide an improved method of annealing strip in coils in which I overcome the tendency of the strip to develop surface scratches.

A more specific object is to provide an annealing method in which the coil convolutions are effectively locked against relative longitudinal movement to prevent surface scratches, but in a way not to cause damage by abrasion or grain breaks.

In the drawing:

FIGURE 1 is a plan view of a coil of steel strip prepared for annealing in accordance with my invention; and

FIGURE 2 is a side elevational view of the core on which I wind the strip.

According to my invention, I wind a cold-rolled continuous steel strip under tension on a core which includes a hollow cylindrical body 12, a pair of spacers 13, and a pair of reinforcing bars 14. I form each spacer of a pipe segment of smaller diameter than the core body. I weld the spacers to the outside of the core body at diametrically opposite sides. The welds extend along each edge of the spacers, as indicated at 15. Before attaching the spacers, I weld the two reinforcing bars 14 to opposite sides of the core body, whereby the central portion of each spacer bears against the respective reinforcing bar. In a typical installation, the core body 12 has an outside diameter of about 16 inches, the spacers 13 are cut from 10 inch pipe, and each spacer encompasses an arc of about 72 of this pipe. It is essential to the successful practice of my invention that I avoid abrupt bends in the strip, such -as would cause abrasions or grain breaks. Hence it 3,294,598 Patented Dec. 27, 1966 is necessary that the spacers each extend around a substantial arc of the surface of the core body. After winding the strip 10 tightly on the core, I apply conventional steel binding straps 16.

Next I anneal the coil prepared as just described at a temperature of at least 1000 F., using conventional equipment. As the convolutions of the coil at the outside and next to the core heat and expand, the non-circular shape of the coil effectively locks them against relative longitudinal movement, and thus overcomes the usual tendency for the surfaces to develop scratches. The reinforcing bars 14 prevent the spacers 13 from collapsing as they soften at high temperatures.

While I have shown and described only a single embodiment of my invention, it is apparent that modifications may arise. Therefore, I do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

I claim:

1. In an annealing process in which cold-rolled continuous steel strip is wound under tension on a hollow core to form a tight coil, and the coil and core are heated to an annealing temperature from the outside of the coil and from the inside of the core, whereby the convolutions of the coil at the outside and next to the core expand first, a method of preventing scratching of the strip surface comprising locking the convolutions of the coil against relative longitudinal movement as they expand during heating.

2. In an annealing process in which cold-rolled continuous steel strip is wound under tension on a hollow core to form a tight coil, the coil is bound with straps, and the coil and core are heated to an annealing temperature from the outside of the coil and from the inside of the core, whereby the convolutions of the coil at the outside and next to the core expand first, a method of preventing scratching of the strip surface comprising shaping the core and coil in a non-circular configuration which locks the convolutions of the coil against relative longitudinal movement as they expand during heating.

3. A method as defined in claim 2 in which the noncircular configuration of the coil avoids abrupt bending of the strip to prevent abrasions and grain brealksi 4. A method as defined in claim 2 in which the core has a cylindrical body and spacers welded to diametrically opposed sides thereof and extending around a substantial arc of the body to avoid abrupt bending of the strip.

References Cited by the Examiner UNITED STATES PATENTS 1,870,577 8/1932 Lamb 148-155 X DAVID L. RECK, Primary Examiner.

C. N. LOVELL, Assistant Examiner.

Claims (1)

1. 2. IN AN ANNEALING PROCESS IN WHICH COLD-ROLLED CONTINUOUS STEEL STRIP IS WOUND UNDER TENSION ON A HOLLOW CORE TO FORM A TIGHT COIL, THE COIL IS BOUND WITH STRAPS, AND THE COIL AND CORE ARE HEATED TO AN ANNEALING TEMPERATURE FROM THE OUTSIDE OF THE COIL AND FROM THE INSIDE OF THE CORE, WHEREBY THE CONVOLUTIONS OF THE COIL AT THE OUTSIDE AND NEXT TO THE CORE EXPAND FIRST, A METHOD OF PREVENTING

Images