US2061380A - Treatment of strip - Google Patents

Description

Nov. l17, 1936. J. c. KIEN-rz. .JR

' TREATMENT OF STRIP Filed April 13, 19:54

W K Y JJII- l: 3.-.?- I l: JuJl-' lvf l I I I I I I I I I I I l I I l l I I l l l I l I I ll m EnH ||||||||||||HNH1||INHUHMHHH u n HHHHHHHIN .Patented Nov. 17, 1936 UNITE-D STATES PATENT lOFFICE N 2,061,380 `'rltrurrrnm'r or s'rnrr Joseph C. Kientz, Jr.,

' Superior Steel Corporation,

Carnegie, Pa., assignorfv to Pittsburgh, Pa., a

This'invention relates broadly to the treatment of strip, and more particularly to the production of annealed strip in coils.' The invention relates still more particularly to a. continuous process by which strip may be annealed and coiled without cracking and to apparatus for continu-I ously treating strip.

It is wellv known to continuously anneal strip as by drawing it from a coil through an annealing chamber and coiling the annealed strip on a reel as it is delivered from the annealing chamber. Due to the softening of the strip during annealing it is subject to cracking when coiled,

particularly, although not exclusively, if coiledunder tension. For example, ordinary carbon steel strip which is passed continuously through an annealing chamber and coiled up on a reel as it is delivered from such chamber` cracks crosswise of the strip at closelyspaced points along its length. j

In order ,to remove the cracks produced upon coiling of annealed strip it has been customary to remove the coil to a cold rolling mill and to pass the strip through such mill to give it a light cold reduction of perhaps one or two thousandths of an inch. This light cold reduction or skin rolling effectively removes the cracks if they are not too pronounced. vThis operationis,

however, undesirable as it entails an additional handling of the strip and an uncoiling and recoiling thereof. It consumes considerable time and requires the expenditure of a considerable amount of unproductive work.

I have found that if strip is passed continuously through annealing apparatus and between reducing rolls before the annealed strip is coiled the `reduction imparted to the strip by the rolls prevents the undesirable cracking, making it unnecessary to remove the coil of annealed strip to a rolling mill and performthe eXtra rolling operation on it. The product thus produced is superior to a product which has been cracked and then cold rolled, because the strains set up in the material by the production and removal of the cracks are absent. I `have also found that if the annealed strip is given a light skin rolling before Abeing coiled a considerably smaller reduction is required to prevent cracking than that which would be required to. remove the cracks once they'had been formed. In some cases a cold reduction half as great as the cold reduction 'necessary to remove-cracks will prevent the formation of cracks. a reduction of one 4thousandth of an inch would be necessary to removel cracks lformed by coiling annealed strip, a reduction of one-half thousandth of an inch would in some cases be sufficient to prevent cracking if imparted to the strip after annealing and' before coiling. This relatively light reductiony enables higher speed For example, if

eliminating an extra operation. It results in 'production of a superior product'at materially reduced cost. A

Care should be taken in utilizing my process to avoid accumulation on the strip during annealing or cooling of deposits which may be detrimental during the rolling step. If dirt or on the strip during annealing or cooling and the strip with such foreign matter on it passes between thereducing rolls, not only is the effectiveness of the rolling step reduced, but the strip is otherwise detrimentally aifected. The resultant productwill be unsightly and undesirable.

for many purposes. For example, if strip is annealed by passing it through a molten lead bath it is likely to accumulate either small deposits of lead or foreign matter in or floating upon the surface of the lead bath. If these deposits remain on the strip during the rolling step the resultant product will be of greatly inferior quality. Such deposits accumulated in an annealingA bath of molten lead are difficult to remove, and I prefer to anneal the strip in an annealing chamber containing a gas. ,The word gas is used as a'word of broad'defnition and not of limitation and is intended to comprehend gases andlvapors of various kinds, such, for example, as' products of combustion, air or other treating gases or vapors utilized in the annealing chamber to' bring 'about desired conditions for the annealing process.

In any event, it is'highly desirable in using my .process to clean-anneal the strip, by which term I have reference to the production of an annealed strip substantially free from moltenlead, dirt or other foreign matter before it passes to the reducing rolls. I do not, however, have reference to the formation or non-formation of oxides on rimental in the rolling step. Although it is preferred to avoid the formation of oxides, this'is not necessary and may in certain cases even be undesirable, and my process may be used to good advantage even when no provision is made for preventing or reducing the formation of oxides on the strip during annealing.` V

My process does, however, lend itself especially well to the production-of-annealed strip substantially free from oxides or having only a very light coating of easily removable 'oxide. This adaptability of the process, as well as other details, objects and advantages thereof, and also the objects and advantages of my apparatus, will become apmethod and a present preferred embodiment of the apparatus. proceeds.

other foreign matter is permitted to accumulate the strip, as the oxides are not particularly detp arent as the following description of a present preferred way of carrying out the process or nealing chamber 3 provided with burners I.

diagrammatically, a present preferred embodiment of my apparatus, in which Figures 1 and l'a taken together constitute a plan view of a present preferred form ofapparatus; and

Figures 2 and 2B taken together constitute an elevational view of the form of., apparatus shown in Figures 1 and la.

I preferably provide one or more elongated chambers shown in the drawing as two parallel tubes or pipes ,2. In the present preferred embodiment of the apparatus each of such tubes or pipes is adapted to have a single strip passed continuously therethrough. Limited portions only of the pipes 2 extend within and through an an- The heat created by combustion of the fuel introduced through the burners 4 is transmitted through the pipes to the strip and is effective for annealing the strip. 'I'he pipes 2 are mounted on rolls 5 to permit expansion and contraction due to ternperature changes.

Coils of strip to be annealed are provided at 6 and the strip is uncoiled and passed over an aligning roller 'l and through awiper 8 which removes dirt,v dust and other accumulations from the surface of the strip. From thevwiper each strip passes into and through one of the pipes 2. It is brought to annealing temperature while within the portion of the pipe Within the heating chamber 3 and is permitted to cool while passing through the remainder of the pipe.'r Ii it is de-.

sired to produce bright-annealed strip a substance preventing or reducing the formation of oxides on the strip may be introduced within the pipe, and in such event both ends of the pipe are preferably closed except for slits just large enough to permit passage of the strip therethrough. For example, kerosene may be applied to the strip, as disclosed in my copending application Serial No. 712,184, flied February 20, 1934. If a non-oxidizing condition is created within the pipe the strip will have a chance to cool while passing through the relatively long portion of the pipe after it has left the annealing chamber but before it reaches the atmosphere. `By the time the strip emerges from the left-hand end of the pipe it will have cooled below rapid oxidizing temperature and any light oxide coating which may form "on the strip may be very 'easily removed. It is possible by the use of the apparatus described to produce bright annealed strip having practically no oxide at all on it and which does not require any subsequent finishing treatment so far as its appearance is concerned.

After the strip emerges from one or the other of the pipes 2 it passes between -a pair of reducing rolls inone of two cold rolling mills 9. By the time the strip reaches the rolls it has cooled suillciently to enable it to undergo immediately a light cold reduction or skinrolling which will prevent cracking when the strip is coiled. After the strip leaves the reducing rolfs it is coiled on one of a pair of reels l0. The power for drawing the strip through the apparatus may be supplied entirely by the reel or entirely by the reducing rolls, which may be driven in a manner well known in the art, or partly by each. In the embodiment shown in the drawing the rolls are not driven, all` the power being supplied by the reels which are driven by motors Il operatively connected with the reels through suitable gearingiand speed reducing mechanism. The rolling mills, reels,

motor. gearing, reducing mechanism, etc., are mounted on aflrm foundation or base l2.

they may tend to produce cracks in the strip-or to otherwisedetrimentally affect the strip.v In the apparatus shown the strip is subjected to practically no stresses other than the tensile stress 'not be undesirable, but under other circumstances 5 necessary to draw it through the apparatus and 10 the light cold reduction' imparted by the rolls 9.

Due to the fact that the strip may remain subl stantially sealed from the atmosphere, while at the same time moving in substantially a straight line, it may not only be relieved of undesirable 15 strains but may also` be cooled below rapid oxidizng temperature before it emerges from the apparatus into the atmosphere and passes between the reducing rolls, resulting in the production of bright annealed strip of decidedly superior 20 quality.

While I have shown and described a present preferred embodiment of the apparatus and described a present preferred way Aof carrying out the process or method, it is to be distinctly un- 25 derstood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

I claim:

1. A method of producing soft annealedstrip 30 in coils, comprising continuously passing the strip through an annealing chamber whereby to anneal it and bring it to such a condition that the strip tends to crack upon being coiled. and thereafter coiling the strip, and prior to coiling the strip 35 subjecting it to a light skin reduction cold'rolling only to such an extent as to prevent it from cracking upon coiling without altering substantially its soft annealed characteristics.`

2. A method of producing soft annealed strip in 40 coils, comprising continuously clean-annealing the strip to bring it to such a condition that the strip tends to crack upon being coiled and to maintain the strip substantially clean and suitable for cold rolling and thereafter coiling the strip, and prior '45 to coiling the strip subjecting it to a light skin reduction cold rolling only to such an extent as toprevent it from cracking upon coiling without` neal it and bring it to such #condition that-the altering substantially its soft annealed character- 50 strip tends to crack upon being coiled and there- 55 after coiling the strip, and prior/to coiling the strip subjecting it to a light skin reduction cold rolling of the order of a thousandth of an inch only to such an extent as to prevent it from cracksoft annealed characteristics. I

4. Apparatus for producing-soft annealed strip l in coils, comprising an annealing chamber through which the strip is adapted to'b'e passed wherebyy ing upon coiling without altering substantially its 60 to ann'eal it and bring it to s'uch a condition that' 65 the 'strip tends to crack upon being coiled, means for coiling the strip, and cold rolling means for acting on the strip after annealing and before coiling, the rolls of said cold rolling means being so related as to subject the strip to a light 70 JOSEPH c. Jn. 75.

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