US1430648A - Process of coating and treating materials having an iron base - Google Patents

Description

Patented Oct. 3, 1922,

a i w J 30. o W n wl ll II I ll Hl/p O Q J. L. HERMAN. I PROCESS OF COATING AND TREATING MATERIALS HAVING AN IRON BAS E.

I APPLICATION FILED FEB. I0, I922. LAMLBAQ Patented @ct. 3, 119232..

matte JOSEPH L. HERMAN, F THUR/TA, ILLINOIS.

PROCESS 01F COATTNG AND TREATING MATERIALS HAVING AN IRON BASE.

Application filed February 10, 1922. Serial no. aascec.

To all whom it may concern:

Be it known that I, JosnPH L. HERMAN,

a citizen of the United States, a resident of Peoria, in the county of Peoria and State of 5 Illinois, have invented new and useful Tmprovements in Processes of Coating and Treating Materials Having an Iron Base, of which the following is aspecification.

This invention has reference to a process of coating and treating materials having an iron base and particularly the coating and treatment of wire used in the fence industry and for telephone and other purposes;

The principal object of the invention is to subject the coated material to a heattreatment during the continuous process of coating such material and preferably immediately uponthe material leaving the molten bath in which the material is immersed or through which the material is moving. Such heat-treatment has for its object an improved coating which will be more resistant to atmospheric rusting and corroding conditions than is ordinary galvanized wire, and which further will permit a heavier coated wire to b'e'used in wire fabricating machines without causing the coating to crack or flake off. as is the case with heavily coated galvanized wire coated by ordinary processes.

The invention has for a further object to apply a heavier coating on the wire with a shorter immersion in molten zinc than is the case with ordinary galvanized wire car- 35 rying heavier coating and the elimination of the usual wiping mechanism. or the necessity for wiping.

A further object of the invention is to per mit the use of higher speeds for galvanizing wire than can be done under the ordinary galvanizing process and atthe same time causing a heavier coating to be formed on the wire. r

Galvanized wire which is to be used for fabricating purposes and more particularly that which is to be used in the manufacture of woven wire fencing must have a relatively heavy coating of spelter in order to be able to-withstand atmospheric corrod ing conditions, and before my invention was developed this was notpossible except at a much increased cost of production.

The universal practice for testing the relative value of spelter on galvanized wire is by the soecalled Preece or copper sulfate test. There are other tests, however, which are used for quantitatively determining the amount of spelter on galvanized wire, such as stripping the coating in caustic soda solut on; in a suitable hydrochloric acid solutlon; in a solution of hydrochloric acid and antimony chloride, and in a lead acetate solution. The copper sulfate test, although not strictly quantitative, is comparative when used under known conditions of temperature and strength, and being a quick test, and one which can be performed by any one after a little experience, has come to be the routine testing medium for galvanized wire coatings.

At the present time there are only two (2) methods in use whereby these necessary heavy zinc (spelter) coatings may be obtained by the hot process of galvanizing. The first method is to pass the wire, as it emerges from the galvanizing bath, through finely divided charcoal. By such a process a smooth, thick coating may be obtained. This method is used for making telephone wire. It has serious drawbacks, however, from an economic standpoint, because the wire must travel at a "cry slow speed, a very high grade zinc must be used, and, furthen more, the coated wire cannot be subjected to the action of wire-fence fabricating machines without having considerable of the zinc coating crack or flake OK the iron base. The second method is to cause the wire to travel at relatively slow speeds, through a bath of molten spelter, the speed depending on the gauge of wire, the thickness of coating desired and the length of the molten spelter bath, and then wiping the wire by passing it between suitable wipes. Tn other words. a wire will have a heavier galvanized coating, as measured bythe copper sulfate test, the longer it remains in the molten spelter; This latter process, too, has its economic drawbacks, because of the slow speeds required, the long spelter pans necessaryand consequently the lessening of the tonnage passing through a galvanizing unit' heat-treater which not only' heat-treats per se, but also evens up the coating as though it had been passed between wipers, An-

. removed by the wipes, as the wire is passed therethrough. It willtherefore be apparent to those skilled in the art'that the higher speedscan be used because it is not necessary for the wire to -remain immersed in the molten bath for as long a period of time as is necessary in the ordinary galvanizing practice. I

In the accompanying drawing there is illustrated diagrammatically the usual or ordinary continuous galvanizing or coating apparatus includin the annealing fur nace, acid bath, flux bath, coating or galvanizing bath, and my heat-treater associated therewith, by means of which my process may be carried out.

My process consists in treating wireas isusual in the ordinary continuous galvanizing of wire, and I have discovered that if instead of carrying spelter at the temperatures ordinarily used in wire galvanizing practice, i. e., 840 F. to 880 F., it is carried at, say. 950 to 1000" Fahrenheit, and that after leaving the spelter passing the wire through heat of, say, 1200 Fahrenheit, I have a superior galvanized product. For example, if a No. 12'. gauge wire (Am erican steel wire gauge) is passed through molten spelter carried at a temperature of approximately 1000 Fahrenhe1t for approximately two seconds and then through heat of approximately 1200 Fahrenheit for approximately seven seconds, and with or without wiping after leaving the -heat treatment, a wire is coated which will stand approximately four one minute immersions in copper sulfate; whereas a similar wire traveling through the spelter at the same time and speed as the treated wire and wiped after leaving the spelter, and not passingthrough the heat-treatment, will stand, as av general rule, not over one minute immersion in copper sulfate. If the latter wire (which I call the control wire) is not passed through a wipe of some kind after it leaves the spelter. then, although I obtain a wire which will stand more than one copper sulfate immersion test, it is very rough, an uncommercial, unsalable product, and cannot be successfully used in fence fabricating machines.

\Vhat I have described for N0. 12 gauge wire is also true for other gauges of wire,

some of the larger gauges such as No. 9

standing ofttimes many more than four copper sulfate immersion tests. I do not, 'of

a course, limit myself to the speeds and temperatures above given because I have found that I may vary the speeds by controlling In an application'of myprocess, I subject a No. 12 gauge wire to a bath of molten spelter held at a temperature approximately 9509; Fahrenheit for approximately one and one-half seconds. Immediately upon the wire emerging from the spelter it enters .a tube heated at approximately 1250 Fahrenheit and remains in .this tube subjected to this heat for approximately seven seconds. The wire then passes to a reel upon which it is coiled. I find that. the heat-treatment to which the wire is exposed not only permits a uniform coating to be carried on the wire but the coating isalso heavier than is the case if I pass the wire through the usual Wipers as it leaves the coating bath and not subjecting the same to the heat-treatment. Heat-treatment as employed by me has reference to such treatment as will produce a physical or chemical change in the material undergoing treatment. Furthermore, the fact that I do not wipethe' coating as it leaves the spelter bath allows a heavier coating to remain upon the wire, this coating being both uneven and brittle if stopped at this point. When, however, the coated wire is subjected to the action of my heat-treatment it not only causes this heavy coat to distribute itself evenly around the wire, but it also eliminates the'brittleness referred to above. I fin'd that there is an apparent bonding action taking place possibly due to .some kind of an, alloying action caused by the heat, and although I have determined the improvement in the coating over that of an ordinary galvanized coating by several hundred tests I am not yet fully-aware as to the exact physical and chemical changes which take place.

The example above given is only one of very many examples which could be cited developed out. of actual practice and for that reasonI do not wish to .limit myself to temperatures, speeds or gauges of wire as specified above. I'have used various gauges of wire from No. 6 to N0. 17 and I have used spelter temperatures as high as 1275 Fahrenheit and I have carried my heater as high as 1450 Fahrenheit. These are not at a higher rate of speed than is the case when my heat-treater is close to the lower end of the range specified. This is particularly true because the larger sizes of wire are usu ally caused to travel at a speed relatively slower than the .smaller'sizes-of wire.

heat-treater toward the higher range of telnperature, such as have quoted above that. I may passmy coated wire therethrough at For example if I am galvanizing a No. 17 gauge wire I may use a speed of one hundred feet per minute. The temperature of the spelter bath may be 1200 Fahrenheit and the temperature of the heat-treater may only be 900 Fahrenheit. On the other hand, the same size wire may be traveling at the rate of one hundred fifty feet per minute and the spelter bath temperature may be 900 Fahrenheit; whereas, the heat-treater might be carried at 127 5 Fahrenheit. The foregoing example illustrates in what manner I may carry the heat-treaterat a relativelyhigh temperature as compared to the coating bath, and vice versa, and it also indicates that by varying the speed of the Wire I may also vary the temperatures of either i the heat-treater, the spelter bath, or both because it is a known fact and old in the art' that thelonger the wire is immersed in the spelter within reasonable limits the heavier will be the coating, even though the wire be wiped. I have shown previously, however, that before myprocess economic use could not be made of the latter fact to equal that produced by my process. It is therefore 0bvious to those'skilled in the art that modifications of the foregoing may be made without departing from the spirit and scope of the invention.

Wire galvanized by my process has an exceptionally smooth coating even Without the use of wipes. advantage, in that I eliminate the production. of reachers which, with the ordinary galvanizing practice are always produced and as such are valueless except as scrap. Furthermore, it is not necessary for me to use excessively long spelter pans, as T have eliminated the necessity for long immersion of the wire in molten spelter.

- I am aware that attempts have been made to treatmetal coated metallic materials by subjecting the same to a heat treatment after coating. Such processes, however, have been mtermittent and not continuous and required a heat-treatment at intervals of time ranging from not less than ten minutes to at least six hours and more, and at This gives me another relatively low temperature as compared wlth the temperature at which such materlals are coated, and continuously moving .such materials through the heat.

2. The process of treating metal" coated materials having an iron base which consists in heat-treating the coated materials at a relatively high temperature as compared with the temperature at which such materials are coated, and continuously movingsuch materials through the heat.

3. The process of treating metal coated materials having an iron base which consists in heat-treating the coated materials and continuously moving such materials through the heat, the temperature of which is dependent upon the speed at which the material is moved.

4. The process of treating metal coated materials havingan iron base which consists in heat-treating the coated materials and continuously moving such materials throughthe heat, the speed at which the materials are moved being dependent upon the temperature to which the materials are heated.

5. The process of galvanizing wire, which consists in continuously moving the wire and during such movement subjecting the same, first-to a molten bath of spelter and upon leaving the bath subjecting the coated same, firstto a molten bath of spelter; secend-removing the wire from the bath, without wiping and finally subjecting the coated wire to a heat treatment.

7. The process of galvanizing wire, which consists in continuously moving the wire and during such movement subjecting the same, first-to a molten bath of spelter; second-removing the wire from the bath without wiping and finally subjecting the coated wire to a heat-treatment and removing the coated wire therefrom without wiping.

8. The process of treating galvanized wire which consists in heat-treating the coated wire and continuously moving such wire through the heat, the temperature of the heat and the speed at which the wire is moved being dependent on the gauge of the wire and thickness of the galvanized coating. I

. Inwitness. whereof I have hereunto affixed my hand this 3rd day of February, 1922.

aosaru L. HERMAN.

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