US1931912A

US1931912A - Method of forming aluminum

Info

Publication number: US1931912A
Application number: US442632A
Authority: US
Inventors: Raymond T Whitzel
Original assignee: Aluminum Company of America
Current assignee: Howmet Aerospace Inc
Priority date: 1930-04-08
Filing date: 1930-04-08
Publication date: 1933-10-24
Anticipated expiration: 1950-10-24

Description

Oct. 24, 1933. R, T w z 1,931,912

METHOD OF FORMING ALUMINUM Filed April 8, 1930 "IIIIIIIInr'I-I'H 'IIIIIIIII 11,111,1 11111101 INVENTOR Patented Oct. 24, 1933 PATENT? OFFICE METHOD OF FORIWING ALULIINUM Raymond T. Whitzel, Massena, N. Y., assignor to Aluminum Company of America, Pittsburgh, Pa., a corporation of Pennsylvania Application April 8, 1930. Serial No. 442,632

2 Claims. (01. 80-60) This invention relates to the'production of aluminum rod, wire, bar, sheet, strip and the like from billets or ingots or semi-fabricated products by rolling, extruding or similar fabri- 5 cating processes, and it is particularly concerned with processes which comprise the continuous fabrication of the metal in both the heated and the unheated condition, the term aluminum being used here, and throughout this specification and in the appended claims, to designate both aluminum base alloys and pure or commercially pure aluminum.

The annealing temperature of aluminum and its alloys is usually between about 300 and 500 C., depending upon the alloy or the purity of the aluminum. The result of heating the metal to such temperatures is to remove from it the hardening and general effect induced by its being worked in a cold condition. Therefore, when it is desirable to place the metal in the condition induced by cold-working, hereinafter referred to as the cold-worked condition, it is necessary that the metal, when being rolled or otherwise cold worked, be maintained at a low temperature. If the temperature of working is within the range of temperature which produces annealing of the metal, or is such that it tends to completely or ipartiallyremove the cold-worked condition, the metal will not be placed in the cold-worked condition desired.

In the various well known processes of fabricating aluminum, it has often been the practice to hot work the metal until certain reduction in cross sectional area has been obtained, and to follow this by cold working it until further reduced in cross sectional area. In such processes it is often desirable to produce, by the coldworking step, a metal having the complete properties of a true cold-worked metal. As explained above, it is then important that the metal as it enters the cold-working operation be at a tem- To obtain this result the practice has or extrusion, is not uniform in temperature, primarily because of the heat which is unequally imparted to the metal by the working operation. When hot-worked aluminum is allowed to cool slowly in the air, these inequalities of temperature between different portions of the metal produce different rates of cooling, depending upon the initial temperature. Also, the ends of a piece cool more rapidly than its intermediate portion, and its exterior more rapidly than its 35 interior. The effect of these varying rates of cooling result in inequalities in its physical properties, which, in some instances, may be expressed as of the order of 3,000 or 4,000 pounds per square inch in tensile strength.

The inequalities in physical structure, working characteristics and properties introduced in aluminum by the difierences in temperatures produced by hot working, and increased by the prior practices of slow cooling, are exemplified in the production of long lengths of aluminum wire, which it is desirable to so produce that they have the same properties and characteristics throughout. One way of producing such wire is to heat an ingot, which may be about three feet long and six inches square in cross section, to a temperature of approximately 500 C., and then hot roll it until it is about one-half inch square. The hot rolled bar or rod is then coiled, and the coil is permitted to cool in air to room'temperature before it is cold worked, as by rolling or drawing, so that the hardening and other effects of cold working may be imparted to it. This way of cooling the bar or rod increases its cost of production, because of the time required and of the labor involved in handling the material. Also, the inner portion of the bar adjacent to the coiling drum, as well as the outer portion which is directly exposed to theatmosphere, cool more rapidly than does its intermediate portion, which results in inequalities of the physical properties a 'of the metal throughout the length of the stock.

e process 0% first hot and then cold working rod, bar, wire:

and the like stock to the end that such stock may no be rapidly and economically produced, and that it may have improved and substantially uniform physical properties.

In the practice of this invention aluminum is first hot worked, as by rolling or extrusion, but preferably the latter, to progressively produce long lengths of rod, bar or other stock, and is then rapidly cooled from its hot-working temperature. The initial hot working temperature of the aluminum may be about 500 0., and in the rapid cooling step its temperature should be reduced to not higher than about 100 C. While the hot-worked stock may be coiled, and the entire coil rapidly cooled by subjecting it to a suitable cooling medium, such as a quenching bath, it is preferred to progressively effect rapid cooling as the stock emerges from the hot working instrumentality. Such progressive cooling may be effected by spraying the stock as it emerges from a hotworking apparatus or mill, or by passing the stock through suitable containers supplied with cooling liquid. By thus rapidly cooling the stock throughout, its physical properties are rendered uniform throughout the length of the stock. In

the preferred practice of the invention the rapidly cooled stock is subjected to cold working, as by drawing or rolling, this being preferably done continuously. In other words, the stock is preferably hot-worked, then rapidly cooled as it emerges from thehot-working instrumentality, and then cold-worked progressively as it emerges from the cooling medium.

Specific ways of practicing the invention as applied to the production of aluminum rod are somewhat diagrammatically illustrated in the accompanying drawing, of which Fig. 1 is a vertical central sectional view through a pair of hot rolls, and through a progressively cooling apparatus at the discharge side of the rolls; Fig. 2 is a similar view of successively arranged pairs of hot and cold-working rolls having a modified form of progressive cooling apparatus arranged between them; and Fig. 3 across sectional view of the apparatus shown in Fig. 2, taken on the line III-III thereof.

Referring first to Fig. 1, an aluminum rod 1 is illustrated as emerging from the last pass, formed by a pair of grooved hot rolls 2 and 3, of a hot mill. As the rod emerges from this roll pass, it enters a quenching cylinder 4 to which a cooling medium, preferably water, is continuously supplied by branch pipes 5 leading from a water supply pipe 6. The steam produced in the cylin? der as well as the water which is not vaporized, escapes primarily through the outer end of the cylinder.

In Fig. 2 a rod 10 is shown as emerging from the last pass, formed by a pair of grooved rolls The upper portion of the cylinder is provided with a plurality of openings 18 for the escape of steam formed in the cylinder, and above the cylinder there is a hood 19 for condensing the steam and deflecting the condensate downwardly into a suitable trough 20 arranged below the cylinder. Water escaping from the ends of the cylinder through the openings in bells l6 and 17 also flows into trough 20. At the outer end of the quenching cylinder, rod 10 passes directly and continuously through a pair of grooved cold working or reducing

rolls

21 and 22, which may be the first of a series of passes of a cold rolling mill for effecting the desired cold rolling of the rod in its cooled state.

In the preferred practice of the invention as illustrated in Fig. 2, aluminum rod is, in a continuous manner, hot rolled, rapidly cooled and cold rolled. Being thus rapidly cooled between hot and cold rolling passes, the full cold-rolling condition of the metal is attained in the cold rolling operation, and the physical properties and characteristics of the metal are rendered uniform from one to the other end of each piece of stock. These advantages, which cannot be fully attained in the prior practices, are realized without the above explained manufacturing costs incident to the prevailing prior procedures. In the cold rolling of the stock it may be reduced to long lengths of wire having fully developed desirable coldrolling characteristics and having uniform physical characteristics from end to end. If in the cold rolling of the wire its temperature is surficiently raised by the heat of working to remove any of the cold-working conditions imparted to the wire, the wire may be rapidly quenched as it emerges from the last pass of the cold rolling mill in the same manner as explained above.

According to the provisions of the Patent Statutes, I have explained the principle and mode of operation of my invention, and have illustrated and described specific ways of practicing it. How= ever, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim as my invention:

1. The continuous method of working aluminum rod, bar, wire and like stock, comprising progressively hot-working the metal and progressively cooling it rapidly from its hot-working.

temperature to a temperature not higher than about 100 C. and thereby causing the stock to have substantially uniform internal structure throughout its length.

2. The continuous method of working aluminum rod, bar, wire and like stock, comprising hot-rolling the metal, subjecting the metal as it emerges from a hot-rolling pass to a cooling medium to rapidly cool it to a temperature not higher than about 100 C. and thereby causing the metal to have substantially uniform internal structure throughout to condition it for uniform internal behavior in cold-rolling, and cold-rolling the metal as it emerges from said cooling medium.

RAYMOND 'r. WHITZEL.