US2369565A - Method of annealing articles - Google Patents

Description

Feb. 13, 1945- c. o. HAASE I METHODS OF ANNEALING ARTICLES Original Filed Nov. 26,' 1942 /A/l//V70/\ 6'. 0. HAASE By my I AfTdR/V y Patented Feb. 13, 1945 iua'rnon or ANNEALING ARTICLES Carl 0. Haase, Baltimore, Md., asslgnor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Original application November 26, 1942, Serial No. 467,065. Divided and this application February 11, 1944, Serial No. 521.951

Claims.

This invention relates to methods of annealing articles, and more particularly to a regenerative water heating system for annealing furnaces.

This application is a division of co-pending application, Serial No. 467,065, filed November 26, 1942.

Water seals are frequently used for preventing the entrance of air into annealing furnaces, since such seals are cheap and effective. Due to the difference in temperature of the tap water generally employed in water seals and, the annealing gas in the heating chamber of the furnace, a considerable amount of heat is absorbed by the water in the water seal. When the heated water. from the seal is withdrawn through an overflow pipe, the heat absorbed by the water is lost.

An object of this invention is to provide methods of annealing articles and more particularly to provide a regenerative water heating system for annealing furnaces.

In general, the invention comprises a method of annealing articles employing an annealing furnace having a water seal for sealing the fumace from the atmosphere, which comprises heating the articles to be annealed, spraying water from the waterseal upon the hot articles in the furnace to cool them, collecting the water flowing from the treated articles in the water seal, and re-spraying the water from the water seal upon articles to be annealed.

Other features and advantages of the invention will become apparent from the following detailed description thereof, when read in conjunction with the accompanying drawing in which the single figure represents a schematic sectional view of an annealing furnace.

In the particular embodiment of the invention disclosed in the accompanying drawing, an annealing furnace is provided with a housing ill which encloses a chamber il divided by a bailie i2 into a heating area i4 and a cooling area l5. An endless conveyor I! located within the hous' ing Ill comprises a motor driven sprocket i6 which is rotated at a constant speed and which, in turn, drives a chain i8 and a wheel I9. The wheel l9 acts merely as a tensioning wheel for the chain i8 and is located in a pit which is normally filled with water, thus providing a water seal to prevent the entrance of air into the chamber ii. A plurality of spool carriers 2i-2l are equally spaced upon the chain l6 for carrying through the chamber ii coils of oxidizable metal wire weighing as much as 600 pounds wound on spools 22-22. A drum 23 formed on the sprocket l6 holds the spools 22-22 in position on the spool carriers 2i2l while they are passing over the sprocket l8. 4

A charging trench 24 provided with a cover 25 is formed in one side of the pit 20 and is filled with water from the pit 20. The spools 22--22 are fed down the charging trench 24 into the pit 20 and upon the conveyor I1 by means of an' intermittently moving conveyor 26 which comprises a pair of sprockets 21 and 26 connected by a chain 23. A number of cross bars 30-40 are spaced'along the chain 29 so as to permit spools 22-22 to be positioned therebetween. When a spool 22 is fed from the conveyor 26 into thepit 20 and onto the conveyor l1; stops 3i, 32 and 33 position the spools 2222 so that they are engaged by the spool carriers 2l 2l. J

The spools 2222 are moved upwardly through the heating area I4 in which electrical heating means 31 are located. The particular type of heating means employed does not constitute part of this invention, but one type of heating means that has proved satisfactory comprises a plurality of heating coils arranged in a grid-like formation and disposed so as to form three heating areas. In the cooling area l5 opposite the heating area l4 are positioned a plurality of spray nozzles 34--34 which are supplied with water pumped from the body of water forming the seal in the pit 20 by a pump 35. The pump 35 is an simpeller type pump having an inlet pipe 36 extending below the surface of the water in the pit 20, and pumps the water up through a pipe 38 to branch pipes 39-39 which feed the nozzles 34-34. A trip 40 is so disposed relative to the path of movement of the spools 22 through the heating chamber ii that it rolls the spools from the spool carriers 2i--2i through an opening 43 in the housing in onto a discharge apron 4i and into a discharge drum 42. A rotating discharge valve 44 positioned within the drum 42 has two recesses 45-45 formed therein for receiving the spools 22-22. A pocket 46 is formed in each recess 45 for the purpose of carrying a spool deposited therein to a rack 48. The recesses 45- 45 in the rotating member 44 are so formed that the'opening 43 is always closed and the heating chamber ll thus is sealed from the atmosphere.

In operating a furnace such as that shown in the accompanying drawing, spools 22--22 carrying coils of wire made of an oxidizable metal, such as copper, are introduced into the charging trench 24, and are inserted in the conveyor'26 one at a time. The water in the water seal is initially heated by passing steam into it, so that as the conveyor 26 moves the spools 2222 slowly down the charging trench 24; the coils of wire carried by the spools become heated through to about the temperature of the water in the water seal, which is about 190 F. to about 200 FL, and the occluded gases in the wire coils expand due to the heat and are forced from the coils by the water. The intermittent movement of the conveyor 26 is timed so that a spool from the conveyor 23 rolls freely down the charging trench 24 toward the stops 3|, 32 and 33 whenever a. spool carrier 2| on the constantly moving conveyor i1 reaches the bottom of the trench 24 and is positioned by the stops in a spool carrier.

The conveyor ll moves the spools 22--22 upwardly through the heating area I4 is which the heating means is located at a rate of movement such that the wire carried by the spools 22-22 becomes thoroughly heated to the proper temperature by the time it reaches the sprocket 1 l6. Since the wire coils on the spools are preheated nearly to the boiling point of water before entering the heating area M, the spools may be moved up past the heating means much faster than if the wire were not preheated and were wetted by relatively cold water having a temperature of about 40 F. to about 70 F. The drum 23 formed on the sprocket l6 supports the heated spools 22-22 as they pass over the top thereof into the cooling area IS. The conveyor ll moves the spools carrying the coiled wire downwardly through the cooling area advancing the spools 22-22 past the cooling nozzles 34--34 located therein which are supplied with heated water from the pit 20. by the pump 35 through the pipes 36, 38 and 39-43. When the water from the nozzles 34-34 is sprayed upon the hot coils of wire carried on thespools 22-22, all of the heat in the coiled wire is utilized either for evaporating the cooling water sprayed thereon into steam or for heating the water sprayed thereon so that as this water flows back into the water seal, it heats the water contained therein.

The generation of steam in this manner has two beneficial effects: First, the steam provides a non-oxidizing atmosphere within the chamber a H which prevents oxidation of the wire that is being treated. Second, it'permits the maintenance of a slight steam pressure within the chamber II which is desirable since it prevents any air from entering therein. The heat abascaccs absorbed by the water that runs 03 after strimng the hot spools 2222 to-maintainthe temperature of the water in the pit 20 between about 190 F. and about 200 F., so that after the furnace has been operating for a short time, the pit water need no longer be heated by steam introduced therein In order to prevent the water in the pit 20 from rising above 200 F., which would cause excessive generation of steam, it is advisable to provide a small flow of cold water into the pit 20, which also maintains the water level constant and compensates for water lost due to evaporation.

The spools 22--22 pass downwardly past the nozzles 34-34 until they strike the trip 40 which is positioned so as to roll the spools 22-22 one at a time from the spool carriers 2l--2l onto the apron 4| and through the opening 43 into the discharge drum 42. The rotatable discharge valve 44 is operated intermittently and in synchronism with the conveyor I! so as to present a recess 45 to the opening 43 simultaneously with the rolling of a spool onto the apron-4| by the trip 40. Each spool 22 is carried in the pocket 46 to a point where it is discharged from the discharge drum 42 onto the rack 48, the construction of the drum 42 being such that it does not allow air to enter the cooling area I5 when a spool is discharged therefrom.

The time required for the entire operation from the time a spool enters the charging trench 24 until it is ejected from the drum 42 is greatly reduced by the use of the regenerative water heating system disclosed in the accompanying drawing. There are several reasons why this remarkable reduction in the time required for the annealing operation is thus effected. In the first place, wire passed through a, water seal containing cold water is cold when introduced into 40 the heating area and both the cold wire, weighsorbed by the water in the water seal is utilized to preheat the wire on the spools as they are advanced down the chargingtrench 24, and is further useful in promoting rapid evaporation of the water ejected from the nozzles 34-34. Since ordinarily tap water has a temperature of approximately 40 F. to 70 F., when it is sprayed onto the hot coils of wire it is so cool that it cools the coils of wire or portions thereof below the boiling point of water and thus permits the cold water to fiow into the convolutions of the coils, so that the coils of wire are wet when ejected from the furnace. Conversely, when the heated water from the water seal is sprayed onto the hot coils of wire, this water is so near its boiling point that it cannot cool the coils of wire below this temperature and, consequently, no water can remain upon the wire which is ejected, cooled and dried from the furnace.

The water that flows from the spools 22-22, the water that does not strike the spools 22-22,

- and the water that is formed by the condensation of steam on the side walls of the chamber H is collected in the pit 20. Enough heat is ing upto 600 pounds,'and the cold water clinging thereto must be gradually heated. The hot water in the water seal, forming part of the above described regenerative water heating system, preheats the wire coiled upon the spools 22-22 to about 200 F., and when the preheated coils of wire are carried by the conveyor I'l into the heating area l4, the hot water still clinging to the wire is quickly heated to the boiling point and evaporated, thus leaving the wire completely dry. Since the wire coils are preheated to about 200 F. before they enter the heating area [4, and because the hot water that remains on the wire is already at a temperature near its boiling point, considerably less time is required to heat the wire to the proper temperature for annealing than is the case where the water in the water seal is cold and 400 to 600 pounds of wire and the water-clinging thereto must be heated beginning at a temperature as low as v electric heating elements 31. The regenerative water heating system hereinabove described materially reduces this loss of heat and, as a result, increases the thermal efliciency of the furnace to such an extent that it is practically self-suflicient after it has been in operation for a short period of time, and very little, if any, steam from an outside source is required.

What is claimed is:

1. The method of annealing articles in a furnace provided with a water seal, which comprises heating the articles to be annealed, spraying water from the water seal upon the heated articles to cool them, collecting the water flowing from the treated articles in the water seal, and re-spraying the water from the water seal upon articles to be annealed.

2. The method of annealing articles in a furnace provided with a water seal, which comprises heating the water in a water seal nearly to the boiling point with heat absorbed from 'within the furnace, preheating articles to be annealed in the water seal, further heating the articles, spraying hot water from the water seal upon the heated articles, collecting in the water seal the water that flows from the articles, the water that is formed by the condensation of steam within the furnace, and water sprayed toward the articles but which does not strike the articles, and respraying the water collected in the water seal upon other heated articles.

3. The method of annealing articles in a furnace provided with a water seal, which comprises heating the articles, spraying the articles with water from a water seal in which the water is heated nearly to the boiling point, collecting in the water seal the water that flows from the articles, the water that is sprayed from the spraying means that does not strike the articles and the water formed by the condensation of steam within the rurnace, and re-spraying the water thus collected in the water seal upon other articles.

4. The method of cooling articles heated in an annealing furnace provided with a water seal, which comprises spraying upon the heated articles water from a water seal in which the water is maintained at a temperature between about 190 F. and about 200 F., collecting the water flowing from the articles in the water seal, and re-spraying the water on other articles.

5. The method of annealing articles in a furnace provided with a water seal, which comprises heatlng the water in the water seal, preheating articles to be annealed in the water seal, further heating the articles, spraying hot wc er from the water seal upon the heated articles to cool them, collecting the water flowing from the articles in the water seal, and re-spraying the water collected in the water seal upon other heated articles.

6. The method of annealing articles, which comprises maintaining a bath or water at a predetermined temperature, immersing articles to be annealed in the bath to preheat them, removing the articles from the bath, further heating the articles, spraying water from the bath upon the heated articles to cool them, and collecting the sprayed water in the bath to supply heat to the bath.

7. The method of cooling copper wire heated to a temperature in excess of 212 F. in an annealing furnace provided with a water seal, which comprises maintaining the temperature of the water in the water seal at from about F. to about 200 F., spraying water drawn from the water seal upon the heated copper wire, and collecting in the water seal the sprayed water flowing from the wire to impart heat to the Water in the seal.

8. The method of annealing coils of copper wire in a furnace provided with a water seal, which comprises heating the water in the seal to a temperature slightly below the boiling point of water, immersing the coils in the seal to preheat them, further heating the coils to a temperature materially above the boiling point of water, spraying hot water from the seal upon the heated coils to cool them, and collecting in the water seal the water that misses the coils, the water that runs from the coils and the water formed by condensation of steamin the furnace, whereby heat is imparted to the water in the seal.

9. The method of annealing coils of copper wire, which comprises maintaining a bath of water at a temperature of from about 190 F. to 200 F., immersing such coils in the bath to preheat them to substantially the temperature of the bath, removing the coils from the bath, further heating the coils to a temperature at least sufllcient to evaporate the water therefrom, spraying water from the bath upon the heated coils to cool them, collecting the sprayed water and any condensed steam in the bath to supply heat to the bath, and re-spraying the water in the bath upon other heated coils.

10. The method of annealing coils of copper wire, which comprises advancing such coils through a. water bath maintained at a temperature of from about 190 F. to 200 F., advancing the preheated coils through a heating zone heated to a temperature at least sufficiently high to evaporate the water from the coils, advancing the heated coils through a spray supplied with water drawn from the water bath whereby the coils are cooled, collecting the sprayed water and any condensed steam in the water bath to supply heat to the bath. and re-spraying the water in the water bath upon subsequently heated coils.

CARL O. HAASE.

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