US870049A - Method of manufacturing sheet metal. - Google Patents

Description

PAT NTED Nov. 5, 1907.-

A. RIDD. METHOD OFIMANUFAGTURING SHEET METAL.

APPLICATION FILED SEPT. 29. 19-05.

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AMBROSE RIDD, OF NEWPORT, KENTUCKY.

METHOD OF MANUFACTURING SHEET METAL.

Specification of Letters Patent.

Patented Nov. 5, 1907.

Application filed Se t b 29. 1905- Serial No, 280,707.

To all whom it may concern:

Be it known that I, Animosn R1131), a citizen of the United States, residing at Newport, in the county of Campbell and State of Kentucky, have invented a new and useful Method of Manufacturing Sheet Metal, of which the following is a specification This invention relates to the manufacture of sheet metal, and particularly to the manufacture of black sheets to be used in the production of planished iron or Russian iron.

One of the principal objects of the invention is to preserve the delicate film of oxid which forms on the sheets during the several operations in reducing the metal from the form of bars to sheets, these oxid films being afterwards densified in the formation of the enamel like surface characteristic of Russian sheet iron and other planished sheets.

A further object of the invention is to preserve the flexibility of the film of oxid and prevent flexing by maintaining the metal at all times at a temperature sufficiently high to avoid checking or chilling of the sheet and consequent injury to the film of oxid.

A still further object of the invention is to provide an improved method of manufacturing sheet metal which consists in rolling a pack of sheets at a high temperature, stripping the sheets apart while still hot in the presence of an oxidizing agent, thereby oxidizing the surfaces and then densifying the oxidized surface by pressure without permitting the sheets to cool below a dark cherry red heat.

In the manufacture of black sheets as ordinarily practiced, the metal in the form of a bar is heated and then passed through the rough rolls and then through the chilled rolls until the sheets are reduced to a sufficient extent. The sheets are then matched; that is to say, assembled in packs of two, three, four or more, and again passed through the rolls until they are of the required gage. During these operations no particular care is taken to preserve the sheets at a high temperature, and in following the ordinary method the sheets are allowed to cool to a considerable extent, especially during the matching operation and after the last pass where the pack of sheets is allowed to cool. After the cooling operation, the edges of the pack are trimmed by shears and then the sheets are stripped or separated from each other. The sheets'resulting from this ordinary method of rolling are known as black sheets and are sometimes used in the manufacture of Russian iron. This metal, Russian iron, is a sheet of iron or steel, both surfaces of which have an enamel-like finish that is formed by condensing and planishing the film of oxid deposited on the surface of the sheet either naturally or artificially. The sheets are then separated from each other when cold or nearly so, and it is found that in practically all cases the oxid between the sheets will be broken and displaced, portions of the films of oxid clinging in spots to one sheet, while other portions cling to an adjacent sheet, so that each separate sheet will have portions of its surface covered with oxid, and other portions uncoated. This condition of the sheets, however, is not objectionable where it is not essential to retain the film of oxid, the sheets for some purposes being placed in a pickling bath in order to remove all trace of the oxid and then coated with tin, zinc or other metal. In the manufacture of Russian iron, however, it is essential that the sheets be provided with perfectly smooth layers or films of oxid of uniform thickness, and if the ordinary sheet manufactured as above described is to be used for the manufacture of Russian sheet iron, the surface of the sheet must be reoxidized, and in such case the film of oxid at one point may be much heavier and thicker than the film at another point, so that in subsequent treatment, the degree of condensation of the oxid will differ at different points throughout the sheet. In carrying out the present invention the utmost care is taken to preserve the integrity of the film of oxid, and in the process to so separate the sheets that the film belonging to each sheet will cling to that sheet alone.

The accompanying drawing is a diagram illustrating apparatus for carrying the invention into effect.

In starting the operation, the bar or ingot is thoroughly cleaned by a chemical or mechanical process or both. The bar or pairs of bars are then heated in a suitable furnace, or in an annealing oven A, and during the heating process there must be no visible lifting of the scale on the surface of the bar or bars. The bar is then taken from the furnace and the oxidizing process begins, owing to the exposure of the metal to the air, which acts as the oxidizing agent. The bar or pair of bars are then taken to the roughing rolls B which are maintained at a high temperature, and given one or two passes. From the roughing rolls the bars are taken to what is termed the chill rolls 0. Said rolls must, also, be maintained at as high a temperature as will admit of successful lubrication of the journals of the rolls, the temperature being from six hundred to eight hundred degrees Fahrenheit,- and higher if possible. The sheets are reduced in pairs in the usual way on these rolls to about sixteen or eighteen gage, this operation occupying about one minute of time.

The rolls are maintained at as high a temperature as possible in order to preserve and densify the film of oxid on the surface of the sheet, and said rolls are geared together, so that both will rotate at uniform speeds in order to avoid any lagging of one or other of the rolls and consequent injury to the film of oxid, the sheets being subjected to no stress except the actual compression during the rolling process. During this rolling process the hot rolls act upon the oxid coated surfaces of the sheets and compress them, and the sheets have been exposed to the air for about one minute.

The thin sheets after being reduced in pairs are stripped apart while at a dark cherry red heat and instantly placed without cooling into an annealing oven or softening furnace D, so arranged that the heating flame will not come into direct contact with the sheets, and the oxidizing process virtually stops the moment the pack enters the furnace. The stripping of the sheets while still hot is of theutmost importance, for the reason that if the sheets are allowed to cool before stripping, the film of oxid will not only be injured by the reduction of temperature but will tend to cling partly to one sheet, and partly to the adjacent sheet. If the sheets are separated while hot, however, each film will cling to the sheet to which it was initially formed, and the two films will separate from each other.

In the ordinary process, as before pointed out, the sheets which have been rolled in pairs or packs, are allowed to cool or partly cool before stripping, and then are allowed to lie on the mill standing or floor, and while cold, or at a comparatively low temperature are matched. This matching process consists in placing three, four, or more sheets in a pack, and the pack is subsequently passed through the rolls. In carrying out the present invention, however, the sheets are not allowed to cool. They are stripped while still at a high temperature in the presence of an oxidizing agent, that is to say, in the open air, and instantly transferred to the annealing or other heating oven in order that such temperature may be maintained. The sheets are then matched in threes or fours in the usual manner, except that the matching takes place in the annealing oven instead of on the mill standing. The pack of sheets is now ready to be run over; that is to say,

passed through the hot rolls 0 once or twice, and then the pack, still at a dark cherry red heat, is ready for the next steps. In front of the rolls is arranged a hot table E which, in the present instance, is formed of a box or casing of wrought or cast iron, the casing inclos ing a combustion chamber which may be supplied with any suitable fuel in order to maintain the table at a high temperature, preferably at a dark cherry red. The pack is placed on this table in order to conserve the heat.

At a point adjacent to the table is a shearing machine F of any ordinary construction.

In carrying out the present invention, the pack of sheets is received from the rolls at approximately a cherry red heat, is placed on the table E, and immediately trimmed by the shears F, and the sheets are then separated while still hot in the open air, which acts as an oxidizing agent, and it is found that when separating in this manner the films of oxid Will split evenly, each film being retained by the sheet on which it was originally formed, and the sheets being thus in perfect condition for the subsequent densifying and planishing process employed in the manufacture of Russian sheet iron. As soon as the sheets are separated from the pack they are at once, before cooling, placed in an annealing oven G, and after being subjected to an annealing operation are in condition for the further steps of the process, there being in practice from thirty to forty sheets in oven G before the next step is proceeded with. At this stage of the operation the further steps may be carried on in accordance with my method patent, issued August 8, 1905, No. 796,452, the sheets being passed through highly burnished finishing rolls H in the manner described in said patent. There is little if any oxidation going on while the sheets are being planished and burnished, as they are not brought into contact with the atmosphere, it being preferred to pass the pack from the rolls to a heating chamber at one side of the mill stand, and then back across to a heating chamber at the opposite side, if necessary.

In. manufacturing the sheets in the manner described, considerable expense is saved in the production of sheets for the manufacture of Russian sheet iron, and the product is more uniform and of greater commercial value than where the usual reoxidizing processes must be carried into effect, the varying thickness of the film of oxid in the latter case being such as to impair the strength of the metal and prevent the production of an enamel-like surface of uniform resisting qualities in appearance.

I claim:-

1. The method of manufacturing sheet metal, which consists in rolling a pack of sheets at a high temperature, stripping the sheets apart while still hot in the presence of oxidizing agents, thereby oxidizing the surfaces, and then densifying the oxidized surface by pressure without permitting the sheets to cool below a dark cherry red heat.

2. The method of manufacturing sheet metal which consists in rolling a pack of oxid coated sheets at a high temperature, stripping the sheets apart while still hot to separate the films of oxid from each other and preserve on each sheet the film of oxid initially formed thereon, the stripping operation being accomplished in the presence of an oxidizing agent, thereby further oxidizing the surfaces, and then densifying the oxid surfaces by pressure. In testimony that I claim the foregoing as my own, I have hereto affixed my signature in the presence of two witnesses.

AMBROSE RIDD. Witnesses H. L. I'IAW'KINS, .TNo. C. Dnsross.

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