CH148203A

CH148203A - Process for welding and melting metals by means of an electric arc.

Info

Publication number: CH148203A
Authority: CH
Inventors: Aktiengesellsc Farbenindustrie
Original assignee: Ig Farbenindustrie Ag
Priority date: 1928-03-14
Filing date: 1929-02-21
Publication date: 1931-07-15

Description

  

  Verfahren zum Schweissen und Schmelzen von     Iletallen    mittelst des elektrischen  Lichtbogens.    Es ist bekannt, bei der elektrischen     Licht-          bogenschweissung    Zusatzelektroden zu ver  wenden, die mit einem Überzug aus Leitern  zweiter Klasse versehen sind.

   Dieser Mantel,  der aus den Oxyden von Magnesium, oder     von          Calcium,    oder     Baryum,    oder den Silikaten  von Natrium oder Aluminium, oder aus den       Karbonaten    von Natrium, oder     Caleium,        Li-          ibium    oder Magnesium, mit     Wasserglasbin-          dung    einerseits, aus     Desoxydationsmetallen,     wie Nickel, Blei, Titan, Aluminium und der  gleichen, die beispielsweise in Form feiner  Späne oder in Pulverform verwendet werden,  anderseits besteht, soll schwerer abschmelzen  als der Draht selbst,

   so     dass    das Abschmelz  ende kraterartig während der     Schweissung     gestaltet wird. Hierdurch tritt eine starke  Beruhigung des     Lielitbogens        und    ein gutes       "Einbrennen"    desselben ein, da das Wandern  des Bogens durch den Leiter zweiter Klasse  unterdrückt wird. Durch die Desoxydations-    mittel soll der Ablauf der     inetallurgischen     Vorgänge im Lichtbogen günstiger gestaltet  werden.  



  Es ist ferner schon vorgeschlagen wor  den, bei der elektrischen     Liebtbogenschwei-          ssung    und     -schmelzung    eine Erhöhung der  Leitfälligkeit der     Lichtbogenatmosphäre     zwecks Herabsetzung der Spannung     dadureh     herbeizuführen,     dass    man der     Lichtbogen-          atmosphäre    Natrium- oder     Lithiumsalze    zu  führt.  



  Es wurde nun gefunden,     dass    man beim  Schweissen und Schmelzen von Metallen     mit-          telst    des elektrischen Lichtbogens die Span  nung -des letzteren um einen wesentlich  höheren Betrag herabsetzen kann, wenn man  gemäss der vorliegenden Erfindung zur     Er-          höliung    der Leitfähigkeit der     Lichtbogen-          atmosphäre    ein Material verwendet, das ein       Alkalimetall,    dessen Atomgewicht minde  stens<B>39</B> ist, enthält und so beschaffen ist,

             dass    sieh im Lichtbogen ein bei     Liehtbogen-          temperatur    wenig     zersetzlicher    und nur lang  sam verdampfender Stoff in fein verteiltem  Zustande befindet, von welchem aus die       Lichtbogenatmosphäre    stark mit Elektronen  versetzt wird.

   Es hat sich gezeigt,     dass    durch  Verwendung eines solchen Materials eine Er  höhung der Leitfähigkeit erzielt wird, wel  che die Beständigkeit, der elektrischen Ent  ladung besonders dann vermehrt, wenn die  Unterhaltung derselben schwieriger ist, so  zum Beispiel bei der     Schweissung    mit Wech  selstrom, in Schutzgasen oder bei der     Schwei-          ssung    von Aluminium, Magnesium, Kupfer,  Nickel und ihren Legierungen, sowie auch  bei der     Abschmelzschweissung.    Das Material  kann zum Beispiel Salze des Kaliums und  anderer     Alkalimetalle    von     höhergm    Atom  gewicht enthalten, welche Salze zweckmässig  halogenfrei sind.

   Als im Lichtbogen wenig       zersetzlicher    Stoff kommen Metalloxyde in  Betracht, deren Schmelzpunkt so hoch liegt,       dass    sie im Lichtbogen möglichst hohe Tem  peraturen annehmen können, bevor das  Schmelzen     bezw.    Verdampfen beginnt, zum  Beispiel die Oxyde von Titan,     Molybdän,     Uran, Wolfram, Chrom, Aluminium oder  Eisen. Diese Oxyde können dann einfach  mit den genannten     Alkalisalzen    vermischt  werden.

   Man kann aber     aueli    mit beson  derem Vorteil solche Salze verwenden, die  chemische Verbindungen der genannten     Al-          kalimetalle    mit Verbindungen der vorer  wähnten Metalle sind, also zum Beispiel       titansaures    Kalium, oder     Kaliumferroeyanid.     Das     titansaure    Kalium dissoziiert unter dem       Einfluss    der     Lichtbogenhitze    in     Titanoxyd,     welches sich als Elektronenstrahler betätigt,  und in Kalium, welches als Ion auftritt. Das       Kaliumferroeyanid    dissoziiert in Eisenoxyd  und Kalium und übt eine analoge Wirkung  aus.  



  Bei der     Lichtbogenschweissung    ahne  Schutzgas kann das genannte Material     iii     Form einer Lösung auf den Zusatzdraht,       bezw.    auf die Elektrode dünn aufgestrichen  werden. Auch kann es in     Pastenform    auf die  Elektrode, oder zum Beispiel bei Abschmelz-         sehweissungen    auf die zu verbindenden  Werkstücke (Bleche) aufgestrichen werden.  In letzterem Fall kann man Elektroden ver  wenden, die mit     Leitern-zweiter    Klasse um  mantelt sind. In beiden Fällen geht das Ma  terial in die     Lichtbogenatmosphäre    über und  erhöht dann die Leitfähigkeit.

   Oder es kön  nen hohle Elektroden mit dem Material ge  füllt werden, das dann ebenfalls in die     Licht-          bogenatmosphäre    übergeht. Bei     Lichtbogen-          schweissung    mit     Schutzgasatmosphäre    kön  nen die benützten Stoffe entweder in der be  schriebenen Weise als Paste auf den Elek  troden Verwendung finden oder in fein ver  teiltem Zustand in die     Schutzgasatmosphäre     eingeführt werden. Benützt man neben dein  Lichtbogen noch die Knallgasflamme, so  können die genannten Stoffe in diese Flamme  vor oder nach der Mischung der Brenngase  eingeführt werden.  



       Dass    mit dem beschriebenen Verfahren  tatsächlich eine ganz erhebliche Erhöhung  der Leitfähigkeit der     Lichtbogenatmosphäre     und damit, eine entsprechende Herabsetzung  der Spannung des Lichtbogens erzielt wird,  zeigen die Ergebnisse der folgenden Ver  gleichsversuche:  Zwei zu schweissende Werkstücke, von  welchen das eine mit dem einen Pol einer       Wechselstromquelle    von üblicher Perioden  zahl verbunden war, wurden mit einer Paste  bestrichen, die aus     Strontium-Wolframat    und       Kupfer-Wolframat,    sowie aus Wasserglas  als     Pastenträger    zusammengesetzt war.

   Der  andere Pol des Lichtbogens war durch eine  blanke     Eisenschmelzelektrode    gebildet.     Die          Schweisssielle    war durch eine Knallgas  flamme erwärmt, welche auch die     Licht-          bogenatmosphäre    bildete. Die Stromstärke  betrug<B>80</B>     Ampere    und die erforderliche  Spannung<B>50</B> bis<B>70</B> Volt.  



  Wurden die gleichen Werkstücke bei im  übrigen gleicher Anordnung mit einer Paste  aus<B>60</B> Teilen     Kalium-Titanat    und 40 Teilen       Kaliumehromat    mit Wasserglas als     Pasten-          träger    bestrichen, so betrug bei gleicher  Stromstärke von<B>80</B>     Amp6re    die erforderliche  Spannung nur<B>30</B> Volt.



  Process for welding and melting ileal alloys by means of an electric arc. It is known to use additional electrodes in electrical arc welding which are provided with a coating of second-class conductors.

   This coat, which is made of the oxides of magnesium, or of calcium, or barium, or the silicates of sodium or aluminum, or of the carbonates of sodium, or caleium, liibium or magnesium, with a water-glass bond on the one hand, from deoxidizing metals, such as nickel, lead, titanium, aluminum and the like, which are used for example in the form of fine chips or in powder form, on the other hand, should melt more heavily than the wire itself,

   so that the melting end is shaped like a crater during the welding. This results in a strong calming of the Lielit arch and a good "burn-in" of the same, since the wandering of the arch is suppressed by the second-class ladder. The deoxidizing agent is intended to make the inetallurgical processes in the arc more favorable.



  It has also already been proposed that in electrical arc welding and melting an increase in the conductivity of the arc atmosphere in order to reduce the voltage by adding sodium or lithium salts to the arc atmosphere.



  It has now been found that when welding and melting metals by means of the electric arc, the voltage of the latter can be reduced by a significantly higher amount if, in accordance with the present invention, one uses to increase the conductivity of the arc atmosphere Material is used that contains an alkali metal, the atomic weight of which is at least <B> 39 </B>, and is of such a nature,

             You can see that in the arc there is a finely distributed material that is not very decomposable at arc temperature and only evaporates slowly, from which the arc atmosphere is strongly mixed with electrons.

   It has been shown that the use of such a material increases the conductivity, which increases the resistance of the electrical discharge, especially when maintaining the same is more difficult, for example when welding with alternating current, in Protective gases or when welding aluminum, magnesium, copper, nickel and their alloys, as well as with fusion welding. The material can contain, for example, salts of potassium and other alkali metals of higher atomic weight, which salts are expediently halogen-free.

   Metal oxides, whose melting point is so high that they can take temperatures as high as possible in the arc, before melting bezw. Evaporation begins, for example the oxides of titanium, molybdenum, uranium, tungsten, chromium, aluminum or iron. These oxides can then simply be mixed with the alkali salts mentioned.

   However, it is also possible with particular advantage to use salts which are chemical compounds of the alkali metals mentioned with compounds of the metals mentioned above, for example potassium titanium or potassium ferroeyanide. Under the influence of the arc heat, the titanium acid potassium dissociates into titanium oxide, which acts as an electron beam, and into potassium, which occurs as an ion. The potassium ferroeyanide dissociates into iron oxide and potassium and has an analogous effect.



  In the case of arc welding without protective gas, said material can be in the form of a solution on the filler wire, respectively. be spread thinly on the electrode. It can also be brushed onto the electrode in paste form, or, for example, in the case of melting welds, onto the workpieces (sheets) to be connected. In the latter case, electrodes can be used that are covered with second-class conductors. In both cases, the material passes into the arc atmosphere and then increases the conductivity.

   Or hollow electrodes can be filled with the material, which then also merges into the arc atmosphere. In the case of arc welding with a protective gas atmosphere, the substances used can either be used as a paste on the electrodes in the manner described or introduced into the protective gas atmosphere in a finely divided state. If the oxyhydrogen flame is used in addition to the arc, the substances mentioned can be introduced into this flame before or after the combustion gases are mixed.



       The results of the following comparative tests show that the method described actually achieves a considerable increase in the conductivity of the arc atmosphere and thus a corresponding reduction in the voltage of the arc: Two workpieces to be welded, one of which is connected to one pole of an alternating current source of the usual number of periods were coated with a paste composed of strontium tungstate and copper tungstate, as well as water glass as a paste carrier.

   The other pole of the arc was formed by a bare molten iron electrode. The welding column was heated by an oxyhydrogen flame, which also created the arc atmosphere. The amperage was <B> 80 </B> amps and the required voltage was <B> 50 </B> to <B> 70 </B> volts.



  If the same workpieces were coated with a paste composed of 60 parts of potassium titanate and 40 parts of potassium ehromat with water glass as the paste carrier with the otherwise identical arrangement, then with the same current strength of 80% > Amp6re the required voltage is only <B> 30 </B> volts.

Claims

PATENT CLAIM I, a method for welding and melting metals by means of the electric light arc, in which substances are introduced into the arc atmosphere to reduce the voltage and increase its conductivity, characterized in that a material is used for this purpose which an alkali metal, the atomic weight of which is at least 39 , contains and is such,

You can see that in the arc there is a finely divided state, which is little decomposable at arc temperature and only slowly evaporates, from which the arc atmosphere is greatly displaced by electrons.

SUBClaims: 1. Method according to claim I, characterized in that at least one salt of such an alkali metal is used in a mixture with at least one metal oxygen compound which is not very decomposable in the arc. -2. Method according to patent claim I and dependent claim 1 characterized in that (let the alkali metal salt be used in a mixture with at least one oxygen compound of titanium.

3. Process according to claim 1 and dependent claim 1, characterized in that the alkali metal salt is used in a mixture with at least one oxygen compound of uranium. 4th

Method according to claim 1 and dependent claim 1 characterized in that the alkali metal salt is used in a mixture with at least one oxygen compound of molybdenum. 5- Process according to claim I and dependent claim 1, characterized in that the alkali metal salt is used in a mixture with at least one oxygen compound of tungsten.

6. Method according to claim I 'and sub-claim 1, characterized in that the alkali metal salt is used in a mixture with at least one oxygen compound of chromium. Method according to patent claim 1 and dependent claim 1 characterized in that the alkali metal salt is used in a mixture with at least one oxygen compound of aluminum.

8. Process according to claim I and dependent claim 1, characterized in that the alkali metal salt is used in a mixture with at least one oxygen compound of iron.

9. -Process according to claim I, characterized in that at least one salt is used which is a chemical compound of at least one alkali metal. the atomic weight of which is at least 39, with at least one metal oxygen compound that is not very decomposable in the arc. 10. Method according to claim I, characterized in that an electrode coated with a solution of the material is used.

11. Method according to claim I, characterized in that an electrode designed as a hollow rod is used, into which the material has been filled. 12. The method according to claim I, characterized in that an electrode coated with a paste containing the material is used. 13. Method according to patent claim I, characterized in that the workpiece is coated with a paste containing the material. 14th

Method according to patent claim 1 and dependent claim 13 characterized in that one uses an electrode which is sheathed with a second class conductor. 15. Method according to claim I, in which a protective gas atmosphere is used, characterized in that the material is introduced into the self-contained gas atmosphere in a finely divided state. 16. Method according to claim I, in which, in addition to the arc, an oxyhydrogen gas flame is used, characterized in that the material is introduced into the oxyhydrogen flame in a finely divided state.

17. Method according to patent claim. I and dependent claim 16, characterized in that the material is fed to one of these components before the components of the oxyhydrogen mixture are mixed. PATENT APPLICATION II: Electrode for carrying out the method according to claim. 1, characterized in that it contains an alkali metal with an atomic weight of at least 39 , as well as a component which is not very decomposable in the arc. and only slowly - evaporates in it.

SUBCLAIMS. 18. Electrode according to claim II, as through. characterized in that it has a content of a mixture of at least one alkali metal salt and at least one metal oxygen compound which is stable in the arc and only slowly evaporates therein.

19. Electrode according to patent claim IT, characterized in that it has a content of at least one alkali metal salt which is a compound of at least one alkali metal with at least one metal oxygen compound, which is not decomposable in the arc and slowly evaporates in it.

0. Electrode according to claim II, characterized in that it is coated with a solution of a substance containing the constituents mentioned. * 21. Electrode according to claim II, there- characterized by the fact that it is coated with a paste containing the components mentioned. 2. Electrode according to claim 11, characterized in that it is designed as a hollow rod which is filled with a material containing the mentioned components.