US1427753A - Method of annealing metal - Google Patents

Description

E. G. BUDD AND J. LEDWINKA.

METHOD OF ANNEALING METAL.

APPLICATION FILED SEPT. 6. I916.

Patented Aug. 29, 1922.

UNITED STATES PATENT OFFlfiE.

EDWARD G. BUIID AND JOSEPH LEDWINKA, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOBS '10 EDWARD G. BUDD MANUFACTURING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA. 1

'HETHOD OF ANNEALING METAL.

Specification of Letters Patent. Patented Aug, 29, 1922,

Application filed September 6, 1916. Serial No. 118,715.

To all whom z't may concern:

Be it known that we, EDWARD G. Bonn and J osnrrr LEDWINKA, citizens of the United States, residing at Philadelphia, in the county of Philadelphia, State of Pennsylvania, have made a certain new and useful Invention in Methods of Annealing Metal, of which the following is a specification.

This invention relates to the method of annealing metals.

The object of the invention is to provide a simple, efficient, economical, and expeditious method of annealing metals.

A further object is to provide a method of the nature referred to which is carried out electrically.

The invention consists substantially in the mode of operation hereinafter set forth, as illustrated in the accompanying drawing, and finally pointed out in the appended claims.

In its broadest scope our invention contemplates subjecting the metal to an annealin heat while removed from the oxidizing .in uence of air, oxygen or other gases. In

a more particular specification of our invention we propose to vinclose the material to be annealed-within an air tight chamber and then exhaust the chamber of its air or other oxidizing gas, and then heat the metal electrically to the required or desired annealing temperature, and finally before removing the metal from the chamber permitting the same to cool sufficiently so that it willnot be affected by or oxidized when again brought in contact with air.

The operation may be carried out in a vast variety of ways and by means of different arrangements of apparatus. While, therefore, we have shown, and will describe various arrangements for carrying our invention into practical operation, we, wish it to be understood that the arrangements shown, are merely illustrative of the. principles involved.

Fig. 1 is a view in perspective, parts broken out and parts in section, showing one form of arrangement adapted for use in carrying out our invention.

Fig. 2' is a view in longitudinal section showing another arrangement suitable for the purposes of our invention.

In accordance with our invention, and referring more particularly to Fig. 1, the material to be annealed say, for example, a

metal sheet orplate 3, is placed within an air tight chamber 4, and is supported and suspended therein by means of clamps 5 connected to its ends. These clamps constitute electric circuit terminals so that the metal sheet or plate, in the example given, forms part of the electric circuit which includes the terminal clamps 5.

Any oxidizing agent contained in the chamber is then removed. This may be accomplished in any suitable or convenient manner, such, for example, as by exhausting said chamber of its air or other oxidizing agent, by means of the pump 6, or other equivalent means, or by supplying the chamher with some inert non-oxidizing agent, as from the supply tank indicated at 7, or the chamber may be exhausted of its air and the inert non-oxidizing agent also supplied, the essentialfeature being the removal of all, or substantially all, oxidizing influence from the closed chamber and the space surrounding the metal to be annealed preparatory to heating the metal.

In Fig. 2. we have shown means for producing a high tension electric spark or discharge, indicated at 8, within the chamber 4, as a means for exhausting said chamber of its oxidizin air,,the spark terminals 10, 10, being inclu led 1n circuit connections 11, 11, supplied with high tension current from any convenient source.

After the removal of the oxidizing a ent, air or gas, or the influence thereof, rom the air tight space surrounding the metal to be annealed, the metal is then heated to the desired annealing temperature. This may be accomplished in any suitable or convenient manner. In practice we have found it practicable and desirable to accomplish the heating of the metal electrically, and in one form of electric heating arrangement suitable for the purpose we propose to employ a heating current of low voltage and big amperage. To this end the clamps 5, constitute the terminals of the secondary coil member 12 of a transformer, which coil is surrounded by the core 13 of the primary coil 14, the latter being supplied with electric current of high voltage and low amperage in'a well known manner. By suitably controlling the current supplied to the primary coil 14 of the transformer a heatgas or ing current of the desired character, capable of heating the metal to be annealed to the desired annealing temperature according to the nature or character of the metal, sheet or plate under treatment, is induced in the secondary member 12 of the transformer.

After the metal has been sufliciently heated to effect the'desired annealing thereof, the current 'is shut off from the primary coil of the transformer and the metal is permitted to cool sufficiently to be unaffected by the oxidizing action of the air, and the c amber is then opened up, the annealed metal is removed, and replaced by a new piece to be annealed, and the process repeated.

From the foregoing description it will be seen that after the metal sheet or plate is placed in the chamber 4, it is maintained in said chamber throughout the heating and preliminary cooling operations without removal. This obviates the necessity of providing air tight gates or passages for the travel of the material to be annealed through the chamber as in the case of continuous annealing operations such as have heretofore been proposed, and which are objectionable for the reason that passages to permit the material to travel through the annealing chamber are diflicult to maintain air tight particularly where the exhaustion of the chamber is carried to any substantial or effective degree, and any access of air or other oxidizing agent through leakage or other cause is detrimental to the annealing action. This trouble we entirely avoid in our process and apparatus wherein the material to be annealed is not only enclosed in the chamber but is maintained therein without movement therethrough during the exhausting or non-oxidizing gas supply, the heating and the cooling operations.

The annealing process above described is effectively carried out expeditiously, economically and satisfactorily. Uniformity of results are attained, and accurate regulation according to the size, character and nature of the material is permitted.

Having now set forth the objects and nature of our invention, and the manner of carrying the same into practical operation, what We claim as new and useful, and of our own invention, and desire to secure by Letters Patent is:'

1. The method of annealing metal which consists in enclosing the part to be annealed and removing therefrom the oxi-e dizing effect of the surrounding medium, and including the same in series in the secondary circuit of an electrical transformer to heat the same to an annealing tem erature, and finally cooling such part be ore exposure thereof to oxidizing influences.

2. The method of annealing metal which consists in surrounding the part to be annealed with an inert non-oxidizing agent and connecting the same in series in the secondary circuit of an electrical transformer to heat the same to an annealing heat, and then cooling such art before exposure thereof to oxidizing influences.

3. The method of annealing metal which consists in including the part to be annealed in series in the secondar circuit of an electrical transformer an removing therefrom oxidizing influences of the surrounding medium while the same is heated to an annealing temperature, and then cooling the same before exposure to oxidizing influences.

4. In an apparatus for annealing metal, a closed chamber within which the part to be annealed is maintained and fixed, a transformer, the secondary of said transformer having its terminals connected respectively to the ends of the part to be annealed, and means to remove the oxidizing influence of the medium contained in said chamber.

In testimony whereofwe have hereunto set our hands in the presence of the subscribing witnesses, on this 30th day of August A. D. 1916.

EDWARD G. BUDD. JOSEPH LEDWINKA.

Witnesses:

L. R. HILYARD, A. H. BUXBAUM.

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