US1980229A - Welding rod - Google Patents

Description

Patented Nov. 13, 1934 UNITED STATES PATENT OFFICE WELDING ROD tion 01' New Jersey No Drawing. Application August 22,1931, .Serial No. 558,842

13 Claims. (01. 219-"s) This invention relates to electrodes for use in welding or deposition of fused metals by what is known as the arc welding process.

It has been recognized for sometime past that B in order to produce the best effects from electric arc welding the deposited fused metal should be free from oxide, occluded gases and other impurities.

Electrodes may consist of a bare metal rod containing fiuxing materials, such as silicon, or they may be metal rods of the pure metal covered with a prepared coatingor they may be rods of metallic alloys such as copper and silicon, coated with a material to give the desired results.

It is of major importance that the coating for the metallic electrode should be composed of such materials as to produce a deposit of the fused metal in proper condition and also to regulate the arc characteristics, otherwise emcient welding and deposition of metals will not be secured.

The coating should be one which will form a crater at the fusing end of the rod and should project or extend a short distance beyond the end of the rod during the welding operation and should burn away at a uniform rate with that of the metal core thus automatically maintaining a fairly uniform projection of the coating beyond the end of the rod.

The coating should also be one which will act as a scavenger and remove the impurities from the molten metal and at the same time protect the molten metal from oxidation while being deposited and solidifying.

The coating should also form a slag of not too heavy character which will tend to float off the impurities from the metal but not contaminate the metal. r I

The coating should further be one which will adhere tothe metal rod and which will permit bending the rod or the rod being thrown about without the coating chipping ofi.

Further, the coating should be water-proof.

Some phases of this invention may be applied to rodsof ferrous or non-ferrous metals but the description is confined largely to that of a coated copper rod suchas is used quite commonly in the application of rail bonds to rails and in the formation of joints in electric conductors of various descriptions, but it may be used for many a" other purposes. I p

The physical properties of the deposited metal may be controlled to a'large degree through the composition of the coating or covering. Materials may be used and form a part of the coating which have an aflinity for the metal of the rod and for oxygen and hence will unite with the same thus producing a non-ferrous alloy of increased hardness and density over that of the pure metal and at the same time produce a reducing action. The coating may be formed of (30 such materials and in such proportions the deposited metal will be substantially free of impurities and of the reducing, fluxing or deoxidizing material and be deposited in substantially its original pure, dense and homogenous state. It has been found that materials such as magnesium, titanium, aluminum and silicon when used in coatings for welding rods produce strong, dense deposits of metals and welds and their efliciency are in the order named. This action may be due to the strong amnity of these materials for oxygen and for forming alloys with the molten metal. Such materials appear in general to have a detrimental effect upon the welding characteristics of the rod, andthat this detrimental effect is greater for those materials which "produce the deposited metals in best condition.

The detrimental effect in the welding characteristics referred to above may be overcome by the addition of such materials as carbon, silica flour, carbids, such as silicon carbid, and carbonates such as of calcium and sodium. These materials also form and extend the coating beyond the end of the' fused rod thus producing the crater before mentioned and. within which the end of the rod is fused, protected from the oxidizing effect of the air.v

As a coating for the metal rod it is found that a mixture of about 40% silicon carbid,10% silica flour (SiO2)5% sodium carbonate (Na2Coa)5% calcium carbonate (09.003) and about 40% of metal modifying and/or reducing materials as stated above will give excellent results. 1

The first four ingredients mentioned produce what might be termed the crater forming portion of the coating and at the same time they tend to protect the molten metal at the fusing end of the rod from direct contact with the air before it has been deprived of its oxygen and as this coating is burned away the removed portion forms the slag hereto mentioned and may or may not have a reducing or de-oxidizing action.

The modifying and reducing material men- 10 tioned above may be either aluminum, titanium, magnesium or silicon, or a combination of any two or more of these materials to secure the desired reducing and/or modif ng action upon the depositedmolten metal. I d that the 40% of modifying and reducing material may be composed of 30% aluminum, 10% titanium, 10% magnesium and 50% silicon. These are all metals and I prefer to use them in a very finely powdered or comminuted state.

The coatings used in the past have in the majority of cases-been formed into a paste or dip by the addition of silicate of soda or an aqueous gum solution such as tragacanth, or. a varnish such as of copal or nitro-cellulose has been used, but these do not hold the coating to the rod sufiiciently or are not waterproof, or the coating is brittle or the binder has a retarding efiect upon the materials of the coating, preventing the best results from being obtained.

During the welding process those ingredients of the coating which have an affinity for the metal core, if used in suflicient quantities, will unite therewith and prior thereto and at the same time have functioned as reducers-or deoxidizers. If the ingredients having an aflinity for the metal core are not used in sufliciently large quantities, but are completely reduced in the welding operation, then there will not remain an amount to unite with the core.

The gum, oil base varnishes and nitro-cellulose binder will adhere to the surface of the rod but when used in sufiicient quantity to do so they are detrimental to the deposited metal and/or are characteristics. If used in sufficiently small quantities not to be detrimental they then donot properly bind the materials of the coating together or to the rod. An additional coating of these binders to the outside of the coating will greatly reduce the chipping away of the coating but at the expense of good welding.

It was found that if the ingredients of the coating, after being thoroughly pulverized and mixed, which'is preferably done in a ball mill altogether, are then mixed with a binder which contains an elastic adhesive such as a binder tion will have a greater degree of elasticity, duetility and toughness than previously used binders.

Rubber cements may be used and-to which may be added an accelerator for hastening the curing either in air or under heat.

A very satisfactory material and one which has little or no detrimental efiect upon the welding characteristics and which can be ,used in sumciently larger quantities to givea satisfactory bindingj-effect of the coating materials and bond between the rod andcoating and which is waterproof, is prepared by masticating undissolved rubber with a reagent adapted to convert it into an isomer having less chemical unsaturation than rubber, then applying heat and causing an exothermal reaction between the two, and then masticating the product. This may then be dissolved in ordinary rubber solvents such as gasolene or benzol. This material is a tough, tacky and nonfriable rubber which may be termed a heat-plastic rubber isomer. Other rubber isomers may also be used. The isomers, free from vulcanizing materials, are better than rubber cements and solutions containing such vulcanizers as sulphur as the sulphur attacks the surface of the metal forming a sulphide which reduces the adhesion between the coating and the metal.

Also the coating material may be mixed with undissolved Para rubber together with a vulcanizing material or mixed with the rubber isomer and the whole mass milled on rolls the same as compounding rubbers for various purposes and this soft mass. can be applied to the rod in-the same manner as wires are now coated or covered with rubber insulation as by extrusion.

A coating suitable for a rod of copper about A,, inchdiamete'r may be prepared by using about 1000 grams of the .powdered ingredients in the proportion hereto mentioned and about 1000 cc of the heat-plastic rubber isomer in solution or slip form. This preparation is applied to the rod by dipping the rod therein and allowing it to air dry or subjecting it to moderate heat. The rod as coated will give a dense deposit of pure copper and excellent Welding characteristics.

The thickness of the coating may be changed by using more or less of the binder or by changing the density of the binder by using more or less solvent. The results to be-secured will require harmonizing the coating composition to secure those results.-

The .rod before coating is preferably oxidized but freed of loose scale or is sand blasted. as such a surface has a stronger adhesion with the coating than a burnished or polished surface found on the rod surface when the rods or wire leave the drawing dies.

The ingredients of the coating other than the 40% of modifying and reducing ingredients may be mixed together and with a rubber solution as heretofore explained .to form a coating dip to be applied to metal rods containing elements such as silicon, manganese, vanadium, titanium, aluminum, etc. which act as a reduceror deo-xidizer, and also as a property modifier to change the physical properties of the deposited metal and weld from that of the pure metal of the rod.

For instance, a copper rod containing silicon and which may be used as a bare rod for are welding and gives a dense deposit or weld can have its welding characteristics changed by applying thereto a coating which will form a projecting shield or crater about the end of the rod as it melts and prevent access of the air to the end of the molten rod and which will form'a light slag coating over the deposited molten. metal.

If desired the modifying and reducing'elements may also be added to the immediately above described coating and this coating applied to the rod containing the silicon or other alloying metals. Also one or more of the modifying and reducing elements may be mixed with a rubber binder to form a coating for a rod.

It is found that at the instant the arc is first started there is a tendency with a coated rod for the coating immediately adjacent the end of the rod to swell up and separate from the rod slight- Various coatings for rods may be prepared'depending upon the metal rod and the results to be secured, and the ingredients of the coating may be mixed with a rubber cement in liquid or paste form or a rubber varnish or with' the rubber gum and worked on rolls or a rubber isomer. The purpose is to mix the ingredients of the coating with a binder of or containing rubber such that the coating will adhere to the metal rod and will be ductile and waterproof.

A covering of rubber may be applied to the coating on the rod and in which silicate of soda has been used as the binder and such rubber covering, applied by dipping or spraying, willform an elastic, yieldable means of retaining the otherwise brittle coating in place and protect it from so easily chipping and will render the coating waterproof.

The term reducin fluxing and de-oxidizing are used as equivalents and the term rubber binder refers to a binder of all rubber or containing rubber, balata, gutta-percha, etc. and y the term rubber isomer is meant a rubber derivative of the same chemical composition as rubber but having some of its properties and characteristics changed.

Binders of varnish, lacquer, gums, etc. must be usedin small amounts and will become hard shortly and do not adhere to the metal of the rod as they should but the rubber binders and especially the heat-plastic rubber isomer in the form of a varnish or cement will adhere strongly to the rod and remain ductile and waterproof.

In welding, an arc is struck between the end of the electrode core and the work to be welded and the fused metal of the electrode allowed to deposit on the work which is simultaneously heated and possibly fused.

There are many variations of the herein described invention which will suggest themselves to those skilled in the art and therefore we wish to be limited only by the claims.

We claim:

1. An electrode comprising a metal core and a coating of crater forming materials consisting of approximately silicon carbide 40%, silica flour 10%, sodium carbonate 5% and calcium carbonate 5% mixed with a binder containing rubber.

2. An electrode comprising a metal core and a coating of crater. forming and reducing materials with a binder containing rubber the craterforming materials comprising approximately 40% silicon carbide, 10% silica flour, 5% sodium carbonate and 5% calcium carbonate, of the total coating material.

3. An electrode comprising a metal core and a coating of comminuted ingredients forming a projecting coating beyond the end of the core as it fuses and held together and to the core by a heat-plastic rubber isomer binder.

4. An electrode comprising a metal core, a coating of substantially 40% reducing material and substantially crater-forming material in comminuted form and a binder of heat-plaster rubber isomer to hold the particles of reducing material together and to the core.

5. A coating preparation for a metallic welding rod comprising a mixture of about 0% minuted ingredients which will have a fluxin or reducing action upon themolten metal of the rod and 60% of a mixture of silicon carbide, silica flour, sodium carbonate-and calcium carbonate and a binder of rubber dissolved in an air drying solvent to form a dip in which the bare rods may be plunged and leaving a coating of the dip upon the rod to dry.

6. An electrode comprising a metal core and a coating thereon containing a crater forming material consisting of about of silicon carbide and the. balance of silica flour, sodium carbonate and calcium carbonate and a binder of tac y rubber isomer.

7. A coating for a coated metallic welding rod comprising crater forming materials of carbides, carbonates and silicon dioxide and a metallic deoxidizing material of about. 40% of the total, all in a finely divided state and a binder of rubber.

8. A welding electrode comprising an alloy metal core of copper and a fluxing metal and a coating thereon of materials which will form a protecting projection about the end of the rod .under action of the arc and protect the molten metal and consisting of about 65% of a carbide, 16% silica and 19% carbonate and a binder of rubber for the coating materials.

9. A welding rod comprising a metal core o copper and a coating of about 60% crater-forming material consisting of silicon carbide, silicon dioxide, sodium carbonate, calcium carbonate and about 40% of a metallic reducing material and a binder of rubber for the coating ingredients.

10. A welding rod comprising a metal core of copper and a coating of substantially 40% silicon carbide, 10% silicon dioxide, 5% sodium carbonate, 5% calcium carbonate, and the balance metallic reducing material, and a binder of a tac y rubber isomer for the coating ingredients.

11. A welding electrode comprising a non-ferrous core and a coating of substantially 40% comminuted fiuxing materials and the balance crater-forming materials bonded together by a rubber heat-plastic isomer.

12. A welding electrode comprising a metallic core and a flexible fluxing coating, the coating comprising a heat plastic rubber isomer having incorporated therein a substantial amount of a metallic carbide in a finely divided state, the isomer forming a flexible binder for the carbide and holding the carbide securely to the core.

13. A welding electrode comprising a metallic core and a flexible coating adhering thereto comprising a substantial amount of silicon carbide and a metallic fluxing material both in comminuted form and bound together and to the core by a binder of tacky rubber isomer.

JAMES M. SAWHILL. GEORGE A. MEAD.