US2870526A - Brass plated rubber adherent steel wire - Google Patents

Description

Jan. 27, 1959 o. E. ADLER l 2,870,526

BRAss PLATED RUBBER ADEERENT STEEL WIRE Filed sept. 23, 1955 FIEE ofwel@ ina/er 5y-n y United States Patent O BRASS PLATED RUBBER ADHERENT STEEL WIRE Orville E. Adler, Niles, Mich., assignor, by mesne assignments, to National-Standard Company, a corporation `of Delaware Application September 23, 1955, Serial No. 536,075 4 claims. (ci. zei- 1835) This invention relates to a rubber coated steel wire, and in particular it relates to a steel wire which-is rst plated with zinc and then with brass to provide a good base for rubber adhesion and also to lengthen the storage life of the wire prior to rubber coating.

Steel wire'which is to be coated with rubber, as is copper which is applied over the zinc must normally be i quite thin. The copper itself does not provide a satisfactory base for rubber adhesion; but migration between the Zinc and the copper produces a brass coating which provides very satisfactory rubber adhesion. This type of wire and the method of making it are disclosed in Domm Patent 2,002,261.

Wire of the type disclosed in the Domm patent is completely satisfactory except that the migration causes a storage problem for the following reasons:

Various rubber mixes require somewhat different brass alloys for best rubber adhesion, with a range between 60% and 80% copper, balance zinc. The optimum for most purposes is 70% copper or 0.425 part zinc to one part copper. The minimum thickness of zinc which is needed for adequate corrosion resistance is about 00004. On the other hand, the thickness of copper which may be used to permit migration of zinc through the copper to produce a thoroughly rubber-adhesive brass alloy at the surface within any ordinary storage time from plating to use ordinarily must be from 000004" to 000010". Migration continues steadily until the copper-Zinc alloy reaches equilibrium for the amounts of the two metals which were originally put on the wire. This means that the copper on zinc wire must be used within a certain length of time or the percentage of zinc at the outer surface will become too high for good rubber adhesion. This may best be shown by converting the thickness figures into equivalent weights of zinc and copper per kilogram of wire. So, for example, on a .037" steel wire the minimum zinc is 4 grams per kilogram of wire, While the copper ranges from .5 to 1.3 grams per kilogram. This means that even with the minimum zinc coating there are from 3 to 8 parts zinc to 1 part copper; so that with excessive storage the wire can go far past the desired copper-zinc ratio for good rubber adhesion. The problem can not be met by using a thick copper coating, because then if the storage time is short the wire surface contains too little zinc for adequate rubber adhesion.

Most conditions of storage and use can be met by providing a wire having a copper coating in the range previously specified. However, it does not satisfy some situations such as export shipment, especially into the tropics,

where there is a long storage period before the wire is used for rubber adhesion and where the wire is exposed to severely corrosive conditions. Wide variations in the time before wire may be used and in the storage conditions to which it may be subjected make it impractical to use the copper on zinc wire. To assure that the wire will not pass the zone of optimum rubber adhesion the copper coating should be thick; but to assure that it will reach that zone by the time it is to be used the coating must be relatively thin. The problem is one of increasing storage life while retaining adherence characteristics.

lt has been supposedthat brass plate on zinc would offer no solution to the problem of increasing storage life while retaining adherence characteristics, because with two plates of equal thicknes surface deterioration through rubber-adherent brass occurs about twice as fast as through copper. This is logical, since the rubber-adherent brass is from 20% to 40%v zinc to begin with, so it must Start away from its optimum percentage of zinc as soonas it is plated, while with copper plate the zinc migration carries it toward the optimum range for some time before it starts to deteriorate from excessive zinc.`

lt has now been Adiscovered that in spiteof the more rapid surface deterioration of brass due to zinc migration, a wire which has over the zinc a brass plate in the range for optimum rubber adherence when fabricated is far more satisfactory for long and severe storage than is a wire having only copper on the Zinc. While the wire may be used immediately, because it is fabricated with a rubber adherent brass alloy coating, it may also be provided with a brass coating of sufficient thickness to carry it through any storage time or conditions which may be encountered, without reducing its rubber adhesion. Thus, contrary to a copper on zinc wire, there is no apparent upper limit to the thickness of brass which may be used and still have satisfactory rubber adherence when used. So, for example, where the range of copper thickness is from 000004 to 000010" for a satisfactory commercial product, a brass plate of 000017 (2 grams per kilogram) may be used.

The invention is illustrated diagrammatically in the drawing wherein:

Fig. l shows a broken view of a wire cut away to show the various coatings; and

Fig. 2 is an end view of the same.

lt is to be understood that the distinct layers of zinc and brass are shown only for purposes of illustration, and that the drawing is necessarily very much out of scale.

An example of the process of the invention will be given in connection with steel tire bead reinforcing wires having a diameter of .037 inch. It will be understood that to maintain the same thickness of zinc and of brass on a heavier wire the weight of zinc and of brass per kilogram of steel must be reduced. The wire has a typical composition as follows:

Percent Carbon .65 Manganese .80 Phosphorous .015 Sulphur .025 Silicon .095

Balance is iron with traces of impurities.

40 grams per liter of zinc and O gram per liter of free cyanide with a pH of 10.6.

The brass plating bath is maintained at a temperature of 150 F. and a current density of 100 amperes per square foot, and with a brass plating tank which is l2 feet long the zinc plated ,Wire is passed through the bath at a speed of 45 feet per minute. Under these conditions a brass plate is deposited on the wire which contains approximately 70% copper and 30% zinc, and has a brass plating weight of 2 grams per kilogram of wire, which on the .037 wire is .000017" thick.

After leaving the brass plating bath the wires are water washed and air dried in the usual manner.

The resulting brass plated-zinc coated steel Wire may be stored for a great many months, and may be shipped and stored under severe conditions of heat and corrosion while still retaining substantially its original effec- 4 layer immediately after deposition having a uniform ratio of copper to zinc throughout, and having a high degree of stability to change in its rubber adherence under adverse climatic conditions.

2. The article of claim 1 in which the brass layer is an alloy containing from 60% to 80% copper, balance zinc.

3. The article of claim 1 in which the brass layer is an alloy containing 70% copper, balance zinc.

4. The method of producing a rubber-adherent ferrous base wire in which the base wire is passed continuously through a molten zinc bath to give it a zinc coating which is at least .00004 inch thick, and the zinc coated wire is then electroplated with a brass alloy'containing from 60% to 80% copper and the balance zinc, to give said zinc coated wire a'uniforrn outerl layer of brass which is at least .000017 inch thick.

`References Cited in the le of this patent UNITED STATESV PATENTS Harris May 22,

Claims (1)

1. A FERROUS BASE ARTICLE HAVING A LAYER OF ZINC THEREON WHICH IS AT LEAST .00004 INCH THICK; AND AN ELECTRODEPOSITED AS SUCH LAYER OF HIGHLY RUBBER ADHERENT BRASS ON THE ZINC WHICH IS AT LEAST .000017 INCH THICK, SAID BRASS LAYER IMMEDIATELY AFTER DEPOSITION HAVING A UNIFORM RATIO OF COPPER TO ZINC THROUGHOUT, AND HAVING A HIGH DEGREE OF STABILITY TO CHANGE IN ITS RUBBER ADHERENCE UNDER ADVERSE CLIMATIC CONDITIONS.

Images