US1868866A - Metal heating furnace - Google Patents

Description

July 26, 1932. M AMBURGY 1,868,866

METAL HEATING FURNACE Filed July 30, 1928 Z-Sheets-Sheet l IVTI //////A it: I

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BY %u+% A TTORNE Y.

July 26, 1932. v M. s. AMB RGY 1,868,866

METAL HEAT ING FURNACE Filed July 30, 1928 2 Sheets-Sheet 2 INVENTOR.

- Patented July '26, 1932 UNITED STATES PATENT orrlcs MARION S. AHBURGY, OF ASELA ND, KENTUCKY, .ASSIGNOR TO THE AMERICAN ROLL- ING MILL COMPANY, OF MIDDLE'IOWN, OHIO, A CORPORATION OF OHIO METAL HEATING FURNACE Application filed July 30, 1928. Serial No. 296,166.

My invention relates to continuous furnaces which are used for annealing, normalizing, or other heat treating of plate sheet an strip metal.

In recent years there has been a considerable development in the heat treating of plates, sheet metal, and strip metal in a rap1d cycle, during a continuous movement of the strip, sheet or plate through a furnace.

The furnaces used for sheet heating in such practices are arranged with driven rollers or discs, which feed the product through the furnace, while in strip heating the product is lon enough to be passed through the fur nace y feeding it in at one end and drawing it out at the other, so that an arrangement of bars which are not driven is practical as a support although not productive of best results, because the surface 'of the product is marred by the bars.

Narrow strips can be drawn through a furnace with edgewise engagement on guides which are bowed downwardly so as to avoid contact with the strip except at the edge. When the strips are wide enough, however, the edgewise engagement cannot thus be provided since the body of the strip will bow down itself and contact with the guides, resulting in marring the surface of the strip.

As a result of this feature, it has been very difiicult to heat strips in this manner except in narrow widths; and box annealing has been adhered to in practice in many instances chiefly because of the fact that the rollers or guides in the furnace mark the strips.

Another expedient employed in heat treating sheets in this manner has been to pass the sheets to be treated through the furnace on waster sheets, which prevent contact of the sheets being treated with the driven rollers within the furnace.

The use of waster sheets is expensive and troublesome, and my practice avoids this.

Again, chains have been used for supporting the sheet metal, but they are expensive to keep up and do'not prevent marking of the product. since they become very hot and it 13 not practical to space them so closely as to avoid use of rollers which contact with thepiece.

reduce the heat in the furnace.

Furthermore all of these expedients employ metallic members passing through the furnace with the sheets, or remaining in the furnace while the sheets pass over them, and in any event subject to the furnace heat. Of course, in modern practice, heat resistant alloys are used; but they are expensive in the first instance, and are subject to a considerable degree of deterioration in any event, so that their use is objectionable. And, as indicated, they do not avoid marking the sheet.

My novel furnace is based on a discovery that I have made that if hot pieces of sheet strip or plate metal are passed over a cold roller or fed by one, within a furnace, that there will be no marking of the hot pieces.

I have tried all types of rollers in heating furnaces in an endeavor to provide one which will not mark a sheet or strip when fed thereover. I find, however, that the effect of passing a highly heated sheet or strip over a rotating or fixed metal support which is also hot, results in the collection on the roller or guide of tiny pieces of oxide, either from oxidation of the guide due to its continued retention in the furnace, or by accumulation from the product being treated. The pieces of oxide build up and then become detached and imbed themselves in the product, resulting in a defect. The oxide nodules also make scratches in the surface of the metal.

The result of keeping the feeding or supporting roller cold is apparently to prevent this effect, and I find that the cold rollers develop what appears to be a polished surface, do not collect oxide, and do not adhere to or mark the metal passing over them.

It is not sufiicient in accomplishing my invention to water-cool the journals of the rollers or supports, or even to provide a water-cooled shaft extending across the furnace, on which a sleeved roller or spaced discs are mounted, because the surface actually contacting with the material being treated must be kept cold.

It'is contrary to the general practice in an annealing, or heat treating furnace to provide cold rollers or guides therein, as they Also I do not find that it is very practical in the typical heat. I

This is because the rollers must be close together' in order to maintain a support for the sheets, since sheetsare ordinarily short in length.

In order to permit of the use of cold rollers in a sheet heating furnace, it is my practice to rivet, weld, or stitch the sheets together into a strip, which permits of a much wider spacing of rollers.

In strip furnaces, of course, the roller spacing is not necessarily close, and as a general proposition, it is best in my furnace to use no more rollers than necessary.

The type of furnace and the type of rollers and the drives thereof, are not essential to my invention, and in order to illustrate a mechanism which embodies my invention, I have selected a standard type of furnace and illustrated my invention in connection therewith. It will be understood that if used for material which is longer than the furnace, it may not be necessary to drive the rollers, although I prefer to drive them in order to maintain the best surface thereon.

I will describe a typical furnace employing my inventiomand set forth in the appended claims the invention therein.

In the drawings:

Figure 1 is a cross section taken vertically through a furnace showing one of my rolls in section.

Figure 2 is a side elevation of a furnace showing the drive for the rolls.

I have shown a furnace having walls 1 and a roof 2, with a surrounding frame generally marked 3. The ends of the furnace may be left open for introduction and discharge of the product, or may be protected by suitable seals, as required.

The bed over which the product is passed and which supports it within the furnace is made up of rollers which are kept cold. The rollers may be formed in a variety of ways, and I have illustrated a simple and effective one.

Thus I illustrate hollow tubes 4 which are supported in journals 5 and 6 at the two outside walls of the furnace I frame or shell. Sprockets 7 are mounted on the tubes, which sprockets are chain-driven from a drive located at the floor line, cated at '8. I may, however, drive my rolls in other manners, as by locating individual motors near the rolls, and connecting them therewith by gears: Or I may, as indicated, leave my rolls undriven.

A drain pipe 9 extends along the side of the furnace, and is equipped with nipples 10, one at each roller, which nipples are connected with fittings 11 in the form of crosses.

The hollow tubular rollers are mounted so that their outer open ends extend into the and generally indi fittings 11, withajoint which may ormay not be packed. The opposite orifice of each cross is filled in each instance with'a plug 12, which has a hole therein for the introduction and support of the water supply pipe for the roller in question.

The water supply pipes 13, to which cold water is supplied, pass through the hollow rollers preferably entirely through the rollers to a point beyond the bearings at the far ends thereof. The rollers are closed at the far ends, and the water supply pipes are equipped with plugs at the entrance ends thereof, which are smaller than the interior of the rollers, and hence supply a circular passage for escape of water.

As so constructed, it will be evident that the water supply can be kept under a head within the rollers due to the fact that the space around the plu is constricted and the operator can keep a ow of water within the rollers, which comes into contact with their walls, at all times, at a temperature at or around the boiling point of, water, without danger of undue development of steam, or can keep the temperature well below the boiling point of water. In my practice, while conditions may vary, the water usually leaves the rolls luke-warm, but I do not need to keep therollers much below the boiling point, this being within the cold range as the term is used in rolling mill practice. Because the rollers conduct alway heat in the furnace, dictates of economysmay prohibit any more chilling than necessary. I do not wish to be limited to any specific temperature, however.

When I am'heat treating sheets, as per my preferred practice, they are joined together end for end to provide a continuous band, thus permitting a wider spacing of the rollers.

In maintaining the water supply to the rollers, it is so controlled as to keep the rollers relatively cold throughout their length.

In 111 practice, using a normalizing heat in the mace of around 1650 degrees Fahrenheit or above, I am able to feed sheets or strips through the furnace without marking the sheets in any way. The rollers do not warp and bend out of shape, and are very long lasting. They soon acquire a high polish, which they maintain throughout t eir li c.

There is no collection of oxide specks, no scratching, and no pitting.

In annealing cold rolled sheets and strips, while the temperature is not so hi h, the

necessity of the cold supporting rol ers just as important, since the annealing is can ducted within the oxidizing range in all types of annealing;

Having thus I claim as new and desire to ters Patent, is

described my invention, what secure by fret- L A. metal treating furnace port for metal therein, which comprises a series of bare hollow tubes of constant diam eter, said tubes having an outlet as large as the internal diameter of said tubes, and means 6 for maintaining a flow of water through said tubes, in full contact with the interior walls of the said tubes.

2. A metal treating furnace having a supa port for metal therein, which comprises a 10 series of bare hollow rolls of constant diameter, said rolls having an outlet as large as the internal diameter of said rolls and means for maintaining a flow of water through said rolls, in full contact with the interior walls thereof, and means for revolving said rolls.

3. A metal treating furnace having a sup-v port for metal therein, which comprises a series of bare hollow rolls of constant internal diameter, said rolls having an outlet as large 2 as the internal diameter of said rolls and means for maintaining a flow of water through said rolls, in full contact with the interior walls thereof, said means comprising a water feed tube extending within said roller 2 from one end to the far end thereof, said far end being closed, whereby the water is caused to return over said feed tube and discharge throu h said outlet. g

4. metal treating furnace having supporting means for metal therein, which means comprise a series of bare hollow rolls and means for maintaining a flow of water through said rolls in continuous contact with the whole inner walls thereof, said means comprising a water feed tube extending withineach 'roll from one end to the far end thereof, said far end being closed,

' whereby the water is caused to return over said feed tube and discharge through the 40 end of said roll, the internal diameter of said roll being constant and a discharge orifice so arranged that steam or air cannot collect in the interior of said roll.

MARION S. AMBURGY.

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