US2343158A - Spatter and cleaning shield for electric arc welding - Google Patents

Description

. metal being welded.

Patented Feb. 29, 1944 ELECTRIC sac mom Frank w. Scott, Mlnneapo o lis,Mlnn., iaalgnor to Marquette Manuhctlring 00., Inc., Minnear oils, Minn, a corporation of Minnesota SerlaIN Application January 12, 1942,

My invention relates to a shield for the portion of metal adjacent the position where an electric weld is to. be made by the arc method.

One object or the invention is to .provide a shield in the form of a solution of substantially paint-like consistency, which may be applied by a paint brush to the metal adjacent the portion to be welded, the shield thereupon 'preventing the spray or spatter of molten metal and slag from the weldingoperation being deponted at undesirable points on the metal.

In connection with the welding of metalsby means of the electric arc the welding process is accompanied-bye. spray or spatter of molten metal and slag from the point where the weld tlons of the ingredients and in the number and character of the ingredients used, ;it is imnecessary to fully describe more than one representative composition suitable for spatter shield purposes, with reference being made to certain variations in the combination of ingredients, some of which may be omitted where unnecessary; The purpose of .the following specification is,- therefore, to give 'a fullunderstanding rod and the metal being welded make-contact- This spray or spatter oi molten metaland slag fuses onto'themetal being welded and requiresconsiderable time and eflort for its removal.

The primary object of the present invention is the provision of a protective coating oi'ilreproof substance that prevents spray or spatter of molten metal and slag from sticking to the Another object of the invention is to provide a spatter shield which may be applied in the form of a thin layer or coating to the metal, the nature of the spatter shield being such that the electric arc is rendered more stable and the physical character of the weld metal is improved, the shield being readily removable alter the welding operation is completed and carrying with it the small particles of metal and slag that would otherwise have fused onto the metal being welded.

Still a further-object is to provides mixture of certain ingredients which may be sold my ytothe user and mixed byhim'with water to the desired consistency, transportion costs thereby being reduced due to the absence or thewater from the ingredients during shipping.

Another object is to provide aprotective coat- .ing having as ltsprincipal ingredient asbestos whereby the coating or shield is unaiiectedb! lire, and, due to its fibrous structure, forms a"- mat to hold the spatter oi molten metal so that. the mat and spatter can be removed after the completion of the welding operation. 7

fiththeseandotherobiectsinviewmyinvention consists in the provision of certain ingredients in combination with each other wherebytbe objects contemplated are attained.

. more fully set forth and in my appended althom 'tbe i-f ventionlsmsoeptibleoturiationinthepmporcrystalline, clay-like minerals, montmorillomite of the invention, both from its constitutional and functional standpoint, and in accordance therewith I have described a desirable embodi me'nt of the invention.

The principal-ingredient of. my spatter shield or protective coating is asbestos. Asbestos is a broad term, as it applies to a kind of material unaflected by. fire. Such material may be a silicate of magnesia and/or lime, and one or more. other metals, as iron, manganese, etc. Asbestos has various mineralogical classifica' tions, as ainphibole, amianthus, chrysolite, serpentineand pyroxene groups of minerals. The use of the general term asbestos, as used in the following-specification, isunderstood to include all-these varieties of mineral silicates.

is characterized by. its fibrous structure. When finely ground and mixed with a suiilcient quantity of water to form a slurry or solution of paint-like consistency, 'the composition may be applied as'a protective coating against weld metal spatter, the ilbersthereupon matting together to form a tough, coherent shield that is not penetrated by the molten particles as they are projected from the weld being made. After welding, this mat holding the spatter is easily brushed oil? or stripped from the surface at the metal.

.oi certain Bentonite is a rock that for spatter cpntains substantially qt percent or more of the olbeidellite. The bentonite that is most suitable composition has agtrong aillnity-ior water, absorbs several times its weight, or as much as ten or more times its volume of water, with a in volume (which may be or more the original volume). 'W u l pe y. Plastic, 8elatinougi maathatreeembles sort soap and holds the finely divided asbestos in an ideal condition may be very deep and entrap slag-v stronger and cleaner welds.

2 y for application, as by-a paintbrushor the like,

tothemetalsurface. In addition to the asbestos and bentonite, I

have found it. convenient, and often necessary,

to use certain proportions of a cleaning composition such as borax or sodium borate, mixed with the asbestos, bentonite and water. In many cases, the metal being welded is dirty and oily r greasy, so that the hydrous slurry does not. spread evenly over the surface of the metal. Theis in addition to the detergent action of bentonite' itself. Bentonite, incleansing, seems to promote emulsions. It absorbs dirt (both solid and liquid) and prevents its return to the-metal surface. The use of borax with the bentonite effectively cleans the metal surface, allows the protective film to spread evenly on the metal surface and thus gives perfect protection.

In addition to the asbestos and bentonite, I have found that the use of borax, or sodium borate, besides acting as a cleaning agent in. the protective coating, aids or improves the stability of the electric arc and improves the soundness of theweld metal deposited. The presence of the alkali vapor in the electric arc lowers the electrical resistance of the air or gas, thus stabilizing the arc itself. This is of particular value when alternating current welding is being done. The

smoother the arc action, the better the weld 1% self will be. Forthis reason, borax or sodium borate is to be considered a desirable ingredient in my protective coating.

Borax or sodium borate in the protective coating'also improves the appearance and strength of the weld metal. The flux on a weld rod forms a. slag as the metal is deposited and covers the of finely divided graphite. As in the case of borax, the stability of the arc gives a more sound and stronger joint in the weld metal itself, as

well as improving the appearance of the joint.

For these reasons, graphite maybe considered desirable in the protective coating. If, however,-

decreasing the power of the coating for preventing the striking of weld metal spatter to the metal being welded. r

The proportions of the foregoing described ingredients may be varied rather widely to secure the desired results and attain the objects contemplated. It is .150 be understood that my claims arenot to be. limited. to a particular analysis. as many proportions of the ingredients give outstanding results. By way of example, I submit the following formula for producing a mixture having exceptionally good, all-around properties. The percentages shown arebased upon weight. I

Ingredient: Per cent Asbest0s Substantially "l5 Bentonite Substantially 9 Borax Substantially 8 Graphite Substantially 8 The foregoing ingredients are then mixed with the proper amount of water to form a smooth, paint-like slurry. Depending upon variations in the characteristics of the dry ingredients and suitable. The resulting slurry is applied by weld metal as a protective film. At times this slag interferes with the smooth flow of the weld metal itself, because the sla has a high temperature freezing point. It may evensolidify along the edges of the weld metal before the weld metal itself is solidified. and in entrapped slag in the weld. Also, .the wavy line on the surface of the weld-metal bead The addition of asbestos, the bentonite, and particularly borax. to the slag, lowers the fusing point of the slag formedbythenuxontherod. Thispermitsthe weld metal. to flow more freely and tends to produce very line-waved beads of excellent appearance. The fluxing action of the borax produces Due to the cleaning action of borax or sodium borate en the metal adjacent the weld, and due Wo improving the stability of the electric arc, g-aswellasimprovingtheappearanceandstrength of the weld metal, Lhave found that borax or sodium borate, whether applied -in solution, as a solid oras a paste, by itselfis desirable as a Thisresultsinaconvexbead upon the consistency'of coating desired by the operator, the amount of water may be varied. In most cases, I flnd' 5.6 parts, by weight, of dry. ingredients and 8.3 parts, by weight, of water.

means of a brush or other suitable means to the seam being welded, and on both sides of the seam, as far as the spatter may beobjectionable. Welding may be done at once, or the coating may be allowed to dry before the welding is begun. It'will befound that the coating will be an effective shield for preventing any sticking of weld metal spatter and the shield may be readily stripped from the metal after the welding process has been completed. Any powder deposit remaining may be readily brushed oif with a dry brush, and the metal does not require any washing, as with certain clay-like types of spatter shields now on the market. I l In accordance with the provisions of the patent statutes, I have described a composition suitable for use as a spatter shield, described the principle of operation and use thereof, and have supplied a formula for the mixture in accordance with my invention. I consider the foregoing specification to represent the best embodiments thereof, but I desire to have it understood I have also found that the stability of the electric are is also increased throu h the addition that the ingredients disclosed, as well as the proportions thereof, are onlyillustrative, and that the invention may be carried out by equivalents which may be reasonably included with the scope of the appended claims without sacrificing any of the'advantages of the invention. What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. A spatter and cleaning shield for electricv arc welding comprising asbestos, bentonite, borax and graphite mixed with suflicient water to form a slurry of paint-like consistency.

2. A spatter and cleaning shield for electric arc welding comprising a slurry formed of as-.

bestos, bentonite, borax, graphite and water the asbestos being predominant.

3. A spotter and cleaning shield for electric -arc welding comprising a composition or asbestos and borax; the'predcminant ingredients being asbestos.

4., A spatter and cleaning shield for electric arc welding comprising a slurrycbntaining the following' ingredients: sfibstantially threeioi rths asbestos and equal parts or bentonite, bore): and graphite, the foregoing ingredients being mixed withfsumcient water to iorm a paint-like slurry to be applied to the metal adjacent the portion thereof to be welded.-

5. A spatter shield for electric welding comprising a composition oi-substantially threefourths asbestos and equal parts of bentonite, borax and graphite.