DE2325708A1 - ARC WELDING PROCESS - Google Patents

Description

-λ -

G 48 896

KOBE STEEL, Ltd., '18-3, 1-Chome, Wakinohama-Cho, Fukiai-Ku, KOBE (JAPAN)

Arc welding process

The invention relates to an arc welding method with an in an electrode inserted into a welding groove, an insulating material being located between the electrode and the walls of the welding groove.

So far in the shipping industry, apart from other branches of industry, the development of production scale welding of relatively short parts of a fuselage, such as an arm, a Side or end plate of a cross brace, arc welding with an electrode inserted lengthways in a welding groove opened up new avenues because of its simplicity and its great effectiveness. It can be assumed that this known method meets the requirements of modern manufacturers or shipbuilders. However, attempts at this have suffered. Kind among many shortcomings and the details contained in the earlier case

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unsolved problems resulting from balancing the electric load and treating a Cabtyre cable because the use of a large capacity of an electric power source has been demanded. Specifically, in the case of multi-layer welding of a plate having a thickness of more than 30 mm, difficulties arose due to the instability of the projection weld bead, poor removability of the slag and low notch toughness of the deposited metal. These difficulties are all due to poor penetration and burn-in of the weld bead due to improper direction of the weld arc created. Due to the nature of arc welding, there is no way to weld a weld groove with a small groove angle. Rather, even in the case of a weld groove with a wider root gap, with the electrode \ A of the weld groove being slightly offset from one side, poor penetration and burn-in is achieved on the side of the groove from which the electrode is further away. The unsuitable alignment of the welding arc according to previous experiments is described in more detail below.

The object of the invention is to create such an arc welding method of the type mentioned, with which it is possible, while avoiding the naphtha parts of known methods, to direct the welding arc in the welding groove to the desired point in order to achieve deep penetration and burn-in. Thereby, it should be possible to keep _r necessary for the welding electric power to tolerable values wherein inaccuracies of the deposited metal is to be avoided as an unstable formation of a projection welding bead and a bead back, poor removability of the slag and a low Kerbzähfestigkeit. Overall, the new arc welding process should enable simple and effective welding.

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The solution to the task at hand is achieved with an arc welding process of the type mentioned achieved in that the path of the magnetic flux generated by the welding current by electromagnetic Means is controlled, whereby the welding arc directed against the desired part in the welding groove and a larger one Penetration can be achieved. According to the invention the arc is aligned in the direction of the lowest magnetic flux density, whereby he indsr welding groove against the desired point with the Aim of greater penetration can be directed. This alignment is achieved by electromagnetic means, wherein for example an auxiliary welding underlay part made from a ferromagnetic one Substance can be arranged above or below the welding groove or wherein the welding pad part of one of the Welding current independent current can flow through. It is also possible to use two welding pad parts in the described To arrange a way through which, for example, alternating currents with a phase difference of 180 ° flow, while a direct current is used as a welding current, thereby alternating the welding arc between the inner walls of the welding groove with the result align with a uniform and deep penetration. These measures enable the penetration to be adjusted in terms of depth by controlling the magnitude of the current flowing through the welding pad. Further Features of the invention emerge from the claims.

With the help of the new arc welding process, it is possible to To direct the welding arc within the welding groove to a desired location, creating a better design of the back of a Weld bead and thus a deeper penetration on the first or base layer of a weld can be achieved. Furthermore can the welding arc is alternately directed towards one of the inner walls of the welding groove using the new arc welding process, to allow a uniform but deep penetration of the weld. Furthermore, the penetration of the Welding can be adjusted depending on the condition or shape of the welding groove. - 4 -

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The invention is explained in more detail below with reference to the drawings .

Figure 1 - a side view of the process of a conventional arc welding process, wherein an electrode is inserted in a welding groove in the longitudinal direction thereof,

Figure 2 - an explanatory example for illustration the penetration achieved with the conventional arc welding process according to Figure 1,

Figure 3 - in side view, the process of an arc welding process according to the invention with an electrode inserted in a welding groove in the longitudinal direction thereof,

FIG. 4 - an illustration to explain the arc welding process method used according to the present invention,

Figure 5 - a cross section along the line V-V from Figure 4,

FIG. 6 is an illustration for explaining the state of penetration according to the arc welding method according to the invention,

Figure 7 is a side view of another example of the invention ,

FIG. 8 - a sketch of an arc welding method according to the invention usable execution type,

FIG. 9 - a side view of an embodiment according to FIG Invention,

Figure Io - a sketch to show the state of magnetic flux in Figure 8,

Figure 11 - a sketch for the representation of the magnetic flux state in the case of a multi-layer arc weld,

Figure 12 is a perspective view of an embodiment with fixed flux according to the invention,

Figure 13 - an embodiment for horizontal welding,

FIG. 14 - a side view of an embodiment for use in a build-up weld,

Figure 15.- a side view of another embodiment for Build-up welding,

FIG. 16 - a perspective view of another example of an arc weld according to the invention,

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Figure 17 is a side view of an example in which a pair is used by auxiliary welding support parts,

Figure 18 is a top plan view of an embodiment used in a gas electro-arc welding process.

Figures 19,

22 and 23 - photographic representations to show those produced according to the arc welding method according to the invention Sweat zone,

Figures 2o,

21 and 24 - photographic representations showing those made by the traditional arc welding process Sweat zones,

Figure 25 - a sketch of a for implementing the invention Procedure applicable embodiment,

characters

26 and 27 - cross sections according to the lines VI-VI and VII-VII in Figure 25,

FIG. 28 - a front view to show the state of a welding groove,

characters
29a, 29b,

29c and ■.

29 d - cross-sections along the lines A-A, B-B, C-C and D-D from FIGS. 28 and

characters
3oa, 3ob,
3oc u.

3od - representations to explain the phase conditions of the electrical currents flowing through the auxiliary welding underlay part at the intersection areas from FIG.

For a better understanding of the arc welding method according to the invention The conventional arc welding process is first described in more detail below with reference to FIG. there an electrode 4 is arranged in a welding groove 2 in the longitudinal direction thereof, with an insulating material 3 between the Electrode and the inner walls of the weld groove. Furthermore, a welding backing strip 6 ″ and one below it are arranged Copper plate on the underside of the welding groove 2 under

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mutual contact provided. Although the sweat produced— curved forward and directed downward due to the force of gravity of the molten material, is along the length of the " Electrode 4 the angle of the downward arc is relatively small, so that the arc produced is substantially horizontal is aligned. This causes only a superficial penetration and a narrow penetration in the area of the welding root (Figure 2). Due to the low penetration, it is not possible to use a conventional arc welding process for this, Type to be used for welding thicker plates or a workpiece that has a large cooling rate or a narrow root joint Has. Even in the case of a further root joint or gap, if an electrode is in a welding groove on one of them, it will be a little offset Place is arranged, a poor penetration arise on one of the inner walls of the weld groove, from which the electrode is further away. .

The inventor has found in experiments that such shortcomings result from improper alignment of the arc produced and it was found that the arc to avoid this error, it should be directed against the root of the weld groove if deeper penetration is required is, and that if necessary, the arc are alternately directed on and between the two inner walls of the welding groove should in order to achieve uniform penetration in every surface of the weld groove.

1st embodiment of the invention

In Figure 3, the new welding method according to the invention f ¹ - fc hidden arc is shown, wherein an electrode 4 is arranged in a space delimited by the inner walls of a welding groove 2 in the longitudinal direction and an insulating material 3 between the electrode and the inner walls the welding groove 2 is, while the melt flux of a powder the welding

- 7 +) (submerged arc welding process)

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zone covers. The secondary side of a welding transformer Io is connected on the one hand to the base metal to be welded and on the other hand to the electrode 4. In addition, there is an auxiliary welding underlay part 8 arranged on the underside of the entire welding groove or part of it and in contact with it, wherein the welding pad is a ferromagnetic substance channel or U-shaped structure and wherein a channel in Welding backing strips 6 'with one arranged underneath Copper plate 6 is placed so that the welding pad strelfen touches the surface of the weld groove.

It is noteworthy that the arc welding method with concealed Arch (ünterpulverwelßverfahren) of the present Invention applicable to the arc welding process with a visible arc is. -

The auxiliary Schwelßunterlageeteil 8 consists of ferromagnetic Substances such as iron, carbon or unalloyed steel, low-alloy steel, etc., and the shape of the welding underlay part According to FIG. 3, 8 can have a U-like channel. However, any other shape, such as an arc of a circle, is also possible, whereby however, the type with a concave and recessed part in the longitudinal direction is preferred for reasons to be explained in more detail below is.

the/
In the following, the operating effect of the submerged arc welding process according to the present invention is explained in more detail with reference to FIGS. 4 and 5. When an electric current flows through an electrical conductor, a magnetic field is created around the substance. In the case of arc welding, in which an electrode is arranged in a welding groove in the manner described, while a welding current flows through the electrode 4 in a direction perpendicular to the plane of the paper and into the plane of the paper, for example according to FIG generated.

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However, when in conjunction with a conventional welding pad copper plate 6 an auxiliary welding underlay part 8 made of ferromagnetic Substance is arranged, the flow goes through the part 8 in such a way that in its channel, so to speak, an area of the smallest The density of the magnetic flux is created on a welding base material placed there. If on the other hand Such a welding support part is not arranged above the welding groove is, a high-density magnetic flux area is generated, which the electrode 4 in a circular arc shape surrounds. A generated arc tends to align against the area with the lowest magnetic flux density, so that the arc is forced downward in the manner shown by an arrow. This means a penetration of the by the arch deposited metal, whereby, as shown in Figure 6, a deep penetration is achieved even in the case when the weld is carried out under the same condition as shown in FIG. As a result, the arc welding method of the invention can also be used for welding of a workpiece with a narrow root or root gap or a thick one Plate with a large cooling rate can be used, which would not be achievable with conventional welding processes. The auxiliary welding pad can be arranged over the entire length of the underside of the welding groove or only over part of the same be where the gap or the root gap is small and therefore where a large penetration is required. On the other hand, in the case of a wide root gap over the entire length of the Welding groove, the amount of deposited metal should be increased, better the auxiliary welding pad over the To arrange welding groove to thereby provide the area with the lowest magnetic flux density over the electrode to the arc to be directed upwards. If the width of the root gap varies along the welding groove, it is recommended to use the auxiliary welding pad to be arranged above or below the welding groove in order to lower the arch for a deeper penetration or for a less deep penetration and upward to increase the deposited metal. According to the invention, with electromagnetic Means a setting or change of the mag-

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Netflussweges made so that the arrangement of the auxiliary welding pad part can be done above or below the welding groove depending on the application. The shape of the welding pad part can be channel-like or plate-like, the channel shape, however, being preferred, around an area of lowest magnetic flux density to be able to generate above or below the welding groove. In the case of the plate shape, the welding backing part can be inside an area of 15 mm from the welding groove, but the described effect when this is exceeded Limit may no longer be attainable.

2. Embodiment

In Figure 7, another embodiment of the arc welding process is shown, wherein the auxiliary welding base part 8 made of ferromagnetic substance is provided in the same way as in the first embodiment, but a second auxiliary welding base part 8 ″ is arranged over the welding groove, which has a lower magnetic Therefore, an area of very high magnetic flux density is generated in a space enclosed with the welding base part 8 ¹ , so that the tendency of the arc to be oriented downward is increased the auxiliary welding support part 8 of ferromagnetic substance are arranged above the welding groove, the alignment of the arc is increased upwards.

Example 1 : The workpiece to be welded has a plate shape, a groove angle of 5o and a root width of 3 mm. A sintered flux material is used and an electrode is located in the welding groove of this workpiece. A triangular electrode (ie with a cross-section of an isosceles triangle with the base 15 mm and one side 20 mm long and with the

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-Ιο-

Cross-sectional area is 15ο mm) with a low Manganese content used. An iron plate 6 mm thick is used as an auxiliary welding underlay part bent so that a channel of circular arc shape is created in cross section, with a maximum Depth of Io mm and a width of 80 mm. This welding backing part is arranged under the welding groove. Then the welding of the type mentioned is carried out with a concealed arc at a current of 160 A. performed * by the triangular electrode flows. The experiment shows that, in contrast to conventional methods, a good weld bead with a perfect back is created.

Example 2 : A workpiece to be welded is used in the form of a plate with a rake angle of 50 and a root gap of 4 mm. Furthermore, a MnO-SiOp series of neutral bond type is used as the flux material and a triangular electrode (with a base of 20 mm in length, a side length of 28 mm and a

Cross-section of 25o mm) with a high Mn-Mo content is used. A Iron plate 8o mm wide and 15 mm thick bent to form a channel with a rectangular cross-section, whereby the width is 8o mm and the depth 50 mm. This welding underlay part is arranged under the welding groove. Then the weld with a hidden arc (submerged arc welding) is carried out with a 24oo A current flowing through the triangular electrode was carried out. The results show that a Weld back with a width of 12 mm and a penetration on one side of the seam of 4 mm Comb can be created while borrowed after the head Process a weld back of 6 mm width and a penetration on one side of the weld seam can be achieved with a depth of only 1 mm.

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In addition to these advantages, the invention enables the following uses and effects:

1. Can even be in the case of a 40 ° groove Back sweat can be achieved.

2. Is this also achievable in the case of a root or Joint gaps of 4 mm and below.

3. The weld back is achievable even in the case of a "Y" type weld groove.

4. Does this even apply in the case of a weld groove with irregular surfaces as a result of a manual Gas cutting.

5. Can also be used in the case of tack welds on the Surfaces of a weld groove a weld bead back ■ can be achieved.

Even when the above conditions are partially met in a weld line, the achievement is possible the uniform weld back is possible. In all of the above cases can be a bad one Penetration can be largely reduced.

- 3 * embodiment

Referring to Figure 8, in which an embodiment of the Submerged arc welding according to the invention is shown, and with reference to Figure 9, which is a side view thereof, an electrode 4 is arranged in a welding groove 2 of a workpiece to be welded, namely with an insulating material a glass strip 3 between the electrode 4 and the inner walls of the welding groove. A melt flux 5 is scattered over it. To provide the formation of the weld ridge, a weld backing material such as a glass strip and one of a Welding support part 7 made of copper plate is arranged as shown on the underside of the welding groove. Then a line a welding transformer 9 with the workpiece to be welded connected while the other line in a known manner

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is connected to the electrode 4. In addition, an auxiliary welding pad part 8 is placed under the welding pad part 7 arranged so that the auxiliary welding pad part 8 from to welding workpiece is electrically insulated, wherein the auxiliary welding base part 8 consists of a material such as iron. Both sides of an auxiliary transformer Io become in phase connected to the auxiliary welding pad part 8. These In-phase connection is derived from a single-phase source of energy to pass through the auxiliary welding backing an electrical current equal to 3 to 50% of the welding current in the same direction as this during the welding process to let flow. When an electric current flows through the auxiliary welding pad part 8 in this way, the Direction of the magnetic flux C due to the through the welding electrode 4 electric current flowing on the underside of the welding groove in the opposite direction to the magnetic flux C ~ due to of the electrical flowing through the auxiliary welding backing part Stroms, so that here a mutual cancellation occurs. On the other hand, the magnetic ones are doubled or strengthened Flows in the area above the weld groove. As the welding arc is to be aligned in the direction of the area of lowest magnetic flux density tends, the bow is directed downwards, while the electromagnetic force by means of an additional electrical A current and a welding current are directed downwards in a similar manner, causing the arc to be directed downwards is further enlarged. As a result, the penetration of the weld seam is extremely good, so that a perfect weld can be achieved is, even if the workpiece is thicker and has a narrow welding groove, moreover, that occupied by the arc Space is smaller as a result of the downward orientation, with the result of a reduced value of the used fluid. This in turn leads to less slag formation and a lower amount of melt flux that flows over the weld groove must be sprinkled. These advantages and features of the weld enable with the help of the downward-facing electromagnetic

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netic force (F) a uniform and smooth surface of the deposited metal with the advantage of easy removability the resulting slag »

Although it is possible to have an electrical current through the copper weld backing part 7 without the use of an auxiliary welding pad 8 to flow, it is remarkable that the auxiliary electrical current. is relatively small compared to the welding current. Accordingly, it is advantageous to use an auxiliary welding underlay part to use with a longitudinal channel 12 to the electrical auxiliary power at the bottom of the Weld groove generated magnetic flux concentrate.

When the connection, the two lines of the auxiliary transformer Io is exchanged for the auxiliary welding pad part 8 in FIG. 8, so that the direction of the auxiliary current reverses, the arc becomes aligned upwards by means of the auxiliary electrical current, while the area of lowest magnetic flux density is above the welding groove is produced. This upward alignment enables an adaptation to the case in which a shallow penetration is possible is required in the basic material.

The relation of the welding transformer 9 to the auxiliary transformer Io and thus the welding current to the auxiliary current can be such that the current is in phase or out of phase and from a single phase electrical power source is derived. Also can be an electric Electricity can be used “to which a phase is given and which is derived from a three-phase power source via a "V" connection or a Scott connection. Furthermore can the current represent a combination of an alternating and a direct current. In the latter case, the sheet pro Half-wave of the alternating current are aligned upwards and downwards, so that a deep penetration in the absence of penetration ■ area or undercut area and reduced. Amount of slag and improved slag removability is achieved. Further advantages are that the molten metal contains

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Tent non-metallic inclusions and gas flow to the surface of the molten metal, creating internal voids in the deposited metal can be avoided, resulting in improved mechanical Properties leads. Such advantages stem from the stormy action of the slag and molten material in the area of the arch, the movement occurring as a result of the upward and downward displacement of the arch.

On the other hand, in the case of multi-layer welding from the ones described below in connection with FIGS. 8 to Io A good weld of the first layer of the deposited metal can be achieved. If the bottom part is a Welding groove of a workpiece 1,1 welded together in the case of a second layer welding to form the first layer welding zone 11 runs from the welding current through the welding electrode 4 and from the auxiliary current through the auxiliary welding underlay part. 8 magnetic flux flowing through the first layer of the welding zone 11, so that the two magnetic forces cancel each other out or reduce its thickness, which aligns the sheet downwards. With reverse phase of the electrical With the current according to the dashed line in FIG. 8, the sheet is aligned upwards for the reasons mentioned.

4th embodiment

Alternatively, if an auxiliary welding support part is used, in which a solid fluid material 16 is arranged in a metallic housing 15 with an elongated channel _17, the auxiliary current can flow through the metal housing 15, thereby avoiding the use of an auxiliary welding support part 8 according to FIG will.

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5. Embodiment

When an example is shown in FIG. 13, the arc welding method according to the invention applied to the horizontal fillet weld. Here is a coated Welding wire 2o arranged next to and along the welding line, and the two connections of the welding transformer 9 are in in a known manner connected to the welding wire 2o and a workpiece 21 to be welded. In addition, the opposite Side of the welding wire 2o with respect to a vertical plate, an auxiliary welding backing part 22 in wire form with a Coating of insulating material arranged. An auxiliary current then flows from the auxiliary transformer Io via the auxiliary welding pad 22. Here, advantages similar to those in the case according to FIG. 8 can be achieved. So the arc can against the auxiliary welding backing part can be directed, and the electromagnetic force generated by the auxiliary current can also be directed upwards will. This avoids the formation of a weld bead with a very large width, which has long been a problem in the field the fillet weld and resulting from the molten metal flowing downwards.

As can be seen from this example, the shape of the auxiliary welding backing part according to the present invention have an elongated channel according to FIG. 8 or, if necessary, one Assume wire shape, but the part should be made of an electrically conductive material =

The auxiliary welding support part 22 can also be connected to the The workpiece must be tack welded in order to or misalignment of the auxiliary welding backing part 22 to prevent during welding. In this case, however, the auxiliary current flows through the workpiece to be welded, with it tends to flow over the area with lower electrical resistance, so that the predominant part of the electrical Current flows through the auxiliary welding pad part 22. A small

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However, a portion of the electrical current also flows through the workpiece 21, which means that there is no noticeable effect on the weld is exercised according to the present invention o This can the Narrow down the fact or affect that of the to be welded Workpiece-isolated arrangement of the auxiliary welding support part a tack weld described above may contain that furthermore the auxiliary welding underlay part with an insulating coating is provided or that the workpiece contains deposits or rust on its surface, whereupon the auxiliary welding support part resting under touch. In other words, the term "insulation" in the present case also includes the condition a, "in which most of the auxiliary current flows through the auxiliary welding backing part flows »

Even if a gravity welder or a welder for low Angle used for fillet welds can be a larger ones resulting from the downward flow of the deposited metal .Welding bead widths can be avoided, since an area of lowest magnetic flux density arises at the point where the two Levels of magnetic fluxes intersect, though the level of the The magnetic flux generated by the welding current does not partially coincide with the flux generated by the auxiliary current.

6th embodiment

Figure 14 shows an example? where the arc welding according to the invention is used in build-up welding. A build-up electrode 32 is disposed on the upper surface of the base material 3o via an insulating material 31 such as a glass strip. The connections a welding transformer are connected in a known manner to the welding electrode 32 and the base material 3ο. An auxiliary welding pad 34 is in contact with the lower surface of the welding groove via an insulating material 33, such as a glass strip, while both connections of an auxiliary transformer Io with the Auxiliary welding pad part 3 4 are connected. In the case of a wiring

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device according to the solid line in Figure 8 and when using a base metal 3o _f which consists of a ferromagnetic substance, the voir auxiliary current and welding current generated magnetic flux will flow through the base material as shown in the drawing, so that in the base material near the welding zone Area of lowest magnetic flux density is generated. As a result, the generated arc is directed downwards, while this effect is increased by an electromagnetic force, which contributes to a further increase in the penetration. If, on the other hand, the base material has been subjected to a heat treatment, or if a steel with a higher carbon content, such as a high-alloy manganese steel, is used as the base metal, whereby the reverse influence of the welding heat on the base material is to be avoided, it is advisable to set the welding current and the auxiliary current in phase opposition the dashed line in Figure 8 so that the arch can be aligned upwards according to the desired smaller penetration =

The build-up weld can be used for lining or »covering chemical apparatus can be used. For example, the coating according to FIG applied by using a build-up weld with corrosion-resistant steel. In this case one is corrosion resistant Steel electrode 41 placed over an insulating material on the inner surface of the reactor ^ while an 'auxiliary welding pad 42 in strip form over an insulating material around the outer surface of the reactor 4o is laid o The auxiliary electrical current flows through the auxiliary welding backing part 42, to thereby one To achieve coating process with a required depth of penetration.

"'S .. _t

Similar to FIG. 8, FIG. 16 shows an arc welding process at which an electrode is arranged in the manner described in a welding groove. Here is an auxiliary welding pad 5o arranged over the weld groove or the weld zone and has

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a plurality of holes 51, which allow entry of the gas generated during the welding “The inner surfaces of the auxiliary welding pad part 5o are with a Insulating material, such as a glass strip 52, coated. In order to align the bow downwards, the direction should be of the auxiliary current flowing through the auxiliary welding backing part opposite to the current flowing through the welding electrode 4. Then an area is made at the bottom of the weld groove lowest magnetic flux density, resulting in a downward alignment of the arc. Of course can have such an auxiliary welding pad Holes 51 can be used for discharging the generated gas if necessary. In addition, the welding pad part is shown in FIG omitted on the underside of the weld groove.

7th embodiment

In Figure 17, an example is shown in which two auxiliary welding support parts 6o and 61 via insulating materials 63 and

64 are arranged on the underside of the welding groove and on opposite sides of this welding groove. Auxiliary alternating currents with a phase difference of 180 flow through the auxiliary welding support parts 6o and 61, while an alternating current is used as the welding current. With this arrangement, the line of magnetic force C1 can be kept constant while the directions of auxiliary electric currents vary at all times, thereby changing the lines of magnetic force C1 and C1. In this way, areas of low and high magnetic flux density are alternately generated by means of the lines of magnetic force C, Q- ^ and C ₃ on both sides A and B of the welding groove. Correspondingly, the bow is represented by an arrow

65 switched from one side to the other. This helps in increasing the penetration resulting in a uniform Surface of the deposited metal, whereby the slag can be better removed and with the removal of gas and

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non-metallic inclusions in the molten metal due to the turbulent movement of the molten material and the Slag is generated so that a deposit of perfect metal can be achieved. Alternatively, a pair of auxiliary welding pad parts can also be used be arranged above or below the welding groove according to the application.

8th embodiment

In addition, auxiliary electrical currents can flow through the auxiliary welding support parts 6o and 61 also direct currents of opposite direction are used, while as welding current a Alternating current is used »It is also possible that the as Auxiliary currents used electrical currents have a mutual phase difference ο In this case, areas become smaller and high magnetic flux density at locations A and B alternately arise so that the arc generated periodically from one side to edge according to arrow 65 is switched. This effect can by using auxiliary sströrnen with a mutual phase difference of 180 ° and an alternating current with a phase difference of 9o ° can be increased as the welding current.,

9- embodiment

Figure 18 shows an example in which the arc welding method of the invention is used in electric gas welding. A welding wire .73 is inserted into a welding groove of the workpieces 7o and 71 to be welded, and auxiliary welding support parts 76 and 77 (in most cases the copper weld backing part) are on opposite sides of the top and bottom of the workpieces 7o and 71 arranged, with insulating materials 74 and 75 between the auxiliary welding pad parts 76 and 77 and the workpieces 7o and 71 are provided. Thereby alternating currents with a phase difference of 180 flow through the

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Auxiliary welding pads 76 and 77, while a direct current . flows through the welding wire 73, so that for the same reasons as in the case of FIG other and between the auxiliary welding pad parts 76 and 77 is switched, which means a reciprocating movement of the sheet. It follows that the uniform surface of the deposited Metal due to the action similar to a weaving or pendulum process and the movement of the molten metal and the slag can be obtained, whereby easy removal of the gas contained in the molten metal is possible.

As in the case of FIG. 17, an alternating current can be used as the welding current, while direct currents are used as auxiliary electrical currents opposite direction can be used. It is also possible to use an alternating current as the welding current while as auxiliary currents, alternating currents with a mutual phase difference to be used. In this respect, however, the auxiliary currents as alternating currents must have a phase difference of unequal I8o ° because the auxiliary currents are symmetrical to the welding current.

It follows from the foregoing that at least one auxiliary welding support part in close proximity to the workpiece, isolated from it and arranged along the weld line. It flows an electric current through the auxiliary welding pad, whereby the generated arc is aligned with the required location in the weld groove, thereby reducing the depth of penetration of the deposited metal. Moreover, can this type of welding process has great advantages find diverse application. It is noteworthy, however, that an attempt has been proposed in which the electric current flows through the molten metal to prevent the undercut of the weld bead. However, it turned out that this method fails when welding a workpiece with a narrow root gap or welding groove and a small groove angle. Compared to conventional

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union procedures, with the disadvantage that in relation to A large electric current is required for the same workpiece. As a result, it cannot be the case with a steel with a higher carbon content applied and would short-circuit the power source if the weld made a large one requires electrical power. With the present invention, as well as the numerous pleasing results, will be such disadvantages avoided.

Example 3;

According to FIGS. 8 and 9, in which each welding equipment is arranged, in-phase alternating currents are used as welding current and auxiliary currents. The photographic cross section of the weld zone thus achieved is shown in FIG. Complete insulation was maintained between the auxiliary welding pad and the workpiece to be welded. The following welding conditions were met:
Workpiece to be welded ...... thickness 32 mm; stole

art SM-5o (Japanese Industrial Standard)

"V" type; Root gap

Groove angle 5ο

Welding groove ..

4 mm

Welding electrode .... isosceles triangular,

high-alloy Mn-Mo base electrode (High Mn-Mo-Base

Electrode) with a base of 20 mm and a height

of 28 mm

Flux basic melt flux type

Welding current ....... 24oo A (AC)

auxiliary electrical power. .... 2oo A (AC) insulating material. »“ .. Glass fiber strips Amount of slag produced ..... 23oo g / m

Example 4 ;

The same condition according to FIG. 3 was used, but with the exception of an electrical auxiliary current of 8oo A (AC) and such an arrangement, that the Auxiliary welding base part the workpiece to be welded

-22-

piece touches, whereby the auxiliary current through both the auxiliary welding backing part as well as flowing through the workpiece to be welded. Figure 2o shows one photographic representation of the cross-section of a weld zone achieved in this way. The amount of generated The slag here was 184o g / m.

As can be seen from Figures 19 and 20, the arc welding method of the present invention operates with an auxiliary welding backing part, which from Workpiece is insulated, a deeper penetration, although the auxiliary current is a quarter of the welding current in comparison with the case where the auxiliary welding pad is not isolated from the workpiece is. This means that when the auxiliary current flows a much larger electrical current is required to penetrate the workpiece to achieve the same depth.

Example 5: Here, the same welding conditions are used with the exception of the use of an electrical auxiliary current. FIG. 21 shows the photographic representation of a cross section of the weld zone thus achieved, and the amount of slag produced in the process was 5750 g / m 2. As can be seen from FIG. 21, the lack of a flowing auxiliary current leads to incomplete melting at the bottom of the weld groove. This means incomplete penetration or errors in the creation of the weld ridge. The slag produced using an auxiliary flow was 23oo g / m 2, which is at least half of the present case at 5750 g / m 2. This means that the arc welding with auxiliary electric power required a smaller amount of flux compared to the case without auxiliary power according to this example

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Example 6: The welding arrangements were as made in Figures 8 and 9, and a filler material containing iron powder was placed between the insulating strip 3 and the workpiece. In-phase alternating currents were used as welding current and as auxiliary current. Figure 22 is a photographic representation of the cross-section of the weld zone thus obtained. The insulation between the auxiliary welding pad and the workpiece was satisfactorily maintained. The following welding conditions were given:

Workpiece to be welded thickness 12 mm,

Steel type SS-41 (Japanese Industrial Standard) Groove angle ..... 5o °, "V" type

Root gap o, 2, 4, 6, 8, Io mm

Welding electrode . _r .... isosceles triangular, base electrode with low carbon content and a base of 14 mm and an eye height of 18 mm Flux sintered flux with an iron powder content

Welding current 125o A (AC)

auxiliary electrical current ...... 4oo A, 2oo A (AC) insulating strips ..... glass fiber strips

According to FIG. 22, a deep penetration was achieved according to the present example, and indeed almost one Penetration too deep when using an auxiliary current of 4oo A (root gap .... ο mm). at the combined use of a metal powder such as iron powder, a good weld bead was obtained. Table 1 below shows the amount of slag produced and the mechanical properties of the deposited steel.

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Table 1 Stretch limit
(kg / mm ² ) tensile strenght
(kg / mm ² ) Root gap
(mm) Amount of slag
(g / m) 31.7 45.5 ο 545 31.1 44.6 2 379 31.6 44.9 4th 4lo 31.4 44.1. 6th 4o6 32.3 44.3 8th 5 oo 31.8 43.5 Io 5o3

Table 1 indicates that the welding process of the present invention produces a minimal amount of slag with satisfactory results mechanical properties generated.

Example 7;

The same condition existed as in Example 6, with the exception of one missing auxiliary stream and one Welding current of 16oo A (AC). This was the longitudinal welding deformation of the workpiece measured, wherein the workpiece according to Example 6 was also measured for comparison. The following Table 2 shows the results-

Table 2 Example 7 Root gap Example 6 + lo-o / looo (mm) ο (mm) o / looo (nm) + 6-9 / 1ΟΟΟ 2 + 1.5 / 10OO + l-5 / looo 4th -1.5 / 1ΟΟΟ + Ο-3 / 1ΟΟΟ 6th o / looo - 4.9 / 1ΟΟΟ 8th o / looo - 8-9 / 1ΟΟΟ Io + 1-2 / 1ΟΟΟ 32-5 Total deformation 4.2 5-4 / 1ΟΟΟ medium deformation o. 7/1000

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From the table above, it can be seen that the welding deformation in the case of using an auxiliary flow was significantly less than in the case without auxiliary flow, namely found one Reduction by the value 1/8 takes place.

Example 8 :

The welding arrangement was as in Figures 8 and 9 hit, and the weld was made with in-phase Alternating currents carried out as welding current and as auxiliary current. Figure 23 presented a photographic Representation of the cross-section of the weld zone achieved in this way. Good insulation was found between the workpiece and the auxiliary welding backing part maintained. The following welding conditions were met:

Workpiece to be welded, thickness 12 mm;

Steel Type SS-41 (Japanese Industrial Standard) Weld Groove ...... Groove Angle 5o; "V" type; Root gap ο mm

Welding electrode with a steel base electrode

low Mn content and with an isosceles triangular cross-section and a base of 14 mm Length and a height of 18 mm

Flux sintered type containing

Iron powder

Welding current I2oo A (AC)

auxiliary electrical power 4oo A (AC)

Amount of slag produced ..... 55o g / m

Example 9: The following welding condition was present, and FIG. 24 shows a photographic representation of the underside of the welding zones thus achieved: Welding electrode ...... Steel base electrode with a low Mn content and an isosceles triangular cross-section with a base of 15 mm length and a height of 2ο mm welding current ...... Γβ'οο A (AC) _ 26 -

auxiliary electrical current ο

309848/1023

The other details were the same as in Example.-TJ :, and the amount of slag produced was 1200 g / m 2. ■ - ;; -.-./.- .:

A comparison of the photographic representation of the back of the sweat (Figure 23) in the case of using an auxiliary stream with the case (Figure 24), in which no auxiliary current is used, shows that even if the total current remains the same, in the case a good weld back can be achieved by using an auxiliary current is what is not possible when there is no auxiliary power. This means that with the arc welding method of the present invention better welding results with compared to conventional Process lower welding current can be achieved. Accordingly, even in the case of using a workpiece that is delicate against the opposite effect of the heat of welding, the present invention can be used successfully because only a low welding current and thus little heat applied so that there is no excessive heat influence on the workpiece is exercised.

The size of the auxiliary current is a function of various conditions, such as the thickness of the workpiece, the groove angle, the root gap, the welding current and a required depth of penetration, however, an auxiliary current of the order of 3 to 50% of the welding current is preferred.

With the present invention numerous advantages can be achieved over the prior art, which are summarized for Examples 2 to 9 as follows:

1. Allows you to combine the use of an exchange and " a direct current as welding and auxiliary current causes a periodic change of direction of the arc, whereby the molten Material and the molten slag are moved with the result of removal of gas and non-metallic inclusions will*. Furthermore, there is a uniform metal structure and a weld zone with a high mechanical strength achieved. -27-

309848/1023

2. Is it possible to adjust the arc periodically? zn change when the arc welding method according to the invention is used in electric gas welding. Thereby he—, gives Siels, an effect similar to the weaving or pendulum process, so that the conventional weaving or pendulum process can be avoided while reducing the width of the welding groove. Further comb

3. in the case of the application of the arc welding process according to the findimiiwjBieiM horizontal fillet weld of the arc in one horizontally or upwards. Through this hardly the problem of a non-uniform leg length of the deposited metal due to the flow process of the molten! metal resulting in good fillet welds be avoided. -

4. Can the arc in the case of using the arc welding method the! Invention in build-up welding against what is to be visually welded WerkstSLck- be straightened, or it is possible to use the bow too stemerm, so that the depth of penetration of the deposited Metal can be reduced .. Also the weld in the case of using a wäraebehaiMäelteii base metal be drilled through, whereby the subsequent heat protection ment can be omitted.

lo. Embodiment

According to this example, the arc generated can be in terms of Depth of restriction by varying the amperage of the Help sstrciiBs, the direction of an electric current and the Phase difference between the welding current and the auxiliary current can be controlled- This embodiment comb successfully there are used where the root gaps or weld grooves vary along the welding limit of a workpiece, will be used below this Aiiisfrähoangsfona with reference to the drawings in more detail explained- In Figure 25 a submerged arc welding is shown,! one electrode in a weld in their

-28-

Is arranged in the longitudinal direction according to FIG. A workpiece 21 has a welding groove of a "Y" type according to the cross section VI-VI from Figure 26 due to poor production, while the weld groove at the other end according to cross section VII-VII of Figure 27 represents a "V" type. Also are an insulating material 23, such as a glass strip, a welding electrode 24, a melt flux 25, a welding backing material 26, a copper welding backing part 27, an auxiliary welding pad part 28, a welding transformer 29, an auxiliary transformer 3o Line rod 31 and an auxiliary power control circuit 32 are provided. This control circuit is used to set the through the auxiliary welding support part 2 8 current flowing from the auxiliary transformer 3o. When welding from the "Y" groove towards the "V" groove according to Figure 5 takes place, so that the auxiliary current is continuous reduced so that the electromagnetic force created by the parallel and in-phase currents of the welding .current and the auxiliary current is generated and the arc downwards aligns, reduced accordingly, whereby the depth of the penetration is reduced. Therefore, the "Y" groove becomes a creates greater attraction for the arch and a gradually smaller or backward attraction for the "V" groove, whereby a constant welding condition despite the different Groove conditions is achievable.

The relation between the groove condition and the phase condition of the electric current is explained in more detail below with reference to the drawings. FIG. 28 shows a workpiece 1 with numerous weld grooves 2. FIGS. 29a, 29b, 29c and 29d form the cross-sections along the lines AA, BB, CC and DD. Figures 3oa, 3ob, 3oc and 3od are explanatory views for showing the phase conditions of the welding current I and the auxiliary current I ₂ at the above intersection areas, the phase differences being represented by 6a, 0b, © c and 6d. The hatching shown indicates the areas in which the currents are coincident with one another and where the 'arc is thereby aligned downwards. -29-

309848/1023

A groove of the "Y ⁿ type in cross-section AA according to FIG. 29a is designed to be flat, so that a deeper penetration is required. For this purpose, in-phase auxiliary currents with a phase difference Bd of almost ο flow through the auxiliary welding underlay part which is close to the Weld groove is arranged, with the result that a deeper penetration and a good weld back can be achieved.

The. "V" groove according to cross section B-B from FIG. 29b represents a groove with no root gap, so that a relatively small Penetration is required. The welding can therefore be carried out with a phase difference of θσ of 90 ° according to FIG. 3ob will. In this case, a deep penetration cannot be achieved even though there is movement of the molten metal in it the weld groove is present with the result of a good weld back. Alternatively, if there is no phase control, a smaller in-phase current can be used as an auxiliary current. The weld groove according to cross section C-C from Figure 29c represents a "V" type with a small root gap, so that the weld without Use of an auxiliary current, or when using an auxiliary current with a phase angle 6d greater than I8o according to FIG 3oc can be carried out. Therefore, the welding arc can be horizontal or oriented upwards, which results in a good sweat bump. Alternatively, if there is no phase control the connection for the auxiliary current can be reversed in order to achieve an anti-phase current of low amperage.

The weld groove according to cross section D-D in Figure 29d represents a "V" type with a large root gap, so that there is an auxiliary current large current strength with a phase difference of 36o according to Figure 3od can be used. Accordingly, the arch is after aligned at the top to limit the formation of the weld ridge, which is as good as in the previous case.

In this way, according to the present invention, the level and the direction of the electric current adjusted to a

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3 0 9848/1023

Adaptation to the different groove shapes with the result of a uniform and good weld. Age-

natively, in the case of an auxiliary welding pad over the Welding groove gives the same results by reversing the phase of the Stroms can be achieved.

On the other hand, there is a tendency for crater formation in close proximity to or under the conduction rod 31. So far made it necessary to remove or avoid such craters, to relocate the line rod 31 from time to time. However, a crater according to the present invention can be successful can be eliminated by adjusting the auxiliary current. if the welding arc comes in the vicinity of the line rod 31, can the auxiliary current can be extremely reduced, or it is also possible to turn its phase difference to the welding current by I8o, so that the parallel currents in antiphase form a repulsive magnetic Create a field which in turn acts on the arch with the result of adjusting the depth of penetration.

As already described, the setting of the auxiliary current enables a uniform weld even when undesired Conditions such as varying groove conditions and occurrence of a crater. For this it is necessary that the auxiliary current of the Control circuit 32 is controlled so that the various shapes of the welding groove can be machined. Such a control method can be achieved by means of a timer or then programmed when the welding speed is constant or when the time course of the weld at a certain position is predeterminable. This then enables a uniform weld bead to be achieved.

11. Embodiment

To automate the control it is possible to check the welding status to be constantly recorded and the data found in this way to be input to the control circuit for the auxiliary current via a feedback.

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3098 * 8/1023

One possibility is to detect the position of the welding arc with a photocell, such as a phototransistor, while the temperature at the back of the weld is detected by a member according to the position of the welding arc, which is contactless and responds immediately to the temperature. This can for example be an infrared-dependent element, so that the Control circuit for the auxiliary current is operated with the output signal obtained in this way. This is how the present invention works to control the orientation of an arc under the influence of an electromagnetic force to thereby to achieve good welding conditions. The following example embodies the controlled welding according to the invention. The materials used in this example are the following:

Thickness of the material to be welded ..... 12 mm

Welding groove 50 ° _f "V" type

Welding length 56o mm

Condition of the root gap ...... half front part .... 6 mm, half back part o-2 mm

Example lo; The above material was welded using the submerged arc welding method described using a flux material of a sintered basic type and a manganese electrode at a welding current of 160 A. Half of the front part with a root gap of 6 mm resulted in a sweat back over 9 mm wide, whereas half of the back part, apart from the crater part, gave no sweat back.

The same material as in the previous case was welded, using an auxiliary transformer and a Control circuit was used for the auxiliary current with a timer. 49 seconds after the start of the Welding, the timer was influenced by an auxiliary current of 4oo A in phase and in direction of the welding current to flow. It resulted

that both front and back halves have good welding

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Connections with a perfect weld back of 6 mm width without the need for post-processing exhibited.

But even when using a timing element for welding, a crater of around 600 mm was created Diameter on both sides at a position of 280 mm from the starting point of the weld. The same was true also for the points of a change in the root gap and at the end position of a weld, where a Weld ridge with a width of 20 to 25 mm was created.

However, if a sweat ridge with a large width is to be avoided, since it is too lateral Leads to the formation of cracks, the aforementioned control circuit for the auxiliary current with a breaker be provided. In the time 40 seconds after the start of the welding, the auxiliary current was up to interrupted the moment the auxiliary transformer was converted to 4oo A in order to avoid the occurrence of a crater. Then the auxiliary current flowed for 30 seconds, before the interruption of the welding current has been switched off in the vicinity of the end part of the weld to avoid the appearance of a crater. As a result, a uniform weld ridge was over scored the whole front and back halves, which was free of craters.

309848 / IQ23

Claims (12)

Patent claims 1.1 Arc welding process with one inserted into a welding groove Electrode, with an insulating material between the electrode and the walls of the weld groove, thereby characterized in that the path of the magnetic flux generated by the welding current is controlled by electromagnetic means, whereby the welding arc is directed towards the desired part in the welding groove and achieves greater penetration will. 2. Arc welding method according to claim 1, characterized in that that an auxiliary welding pad made of ferromagnetic substance is arranged at least above or below the welding groove. 3. Arc welding method according to claim 2, characterized in that that a first auxiliary welding backing part made of a substance of lower magnetic permeability at least above or below the welding groove is arranged, while a second welding base part made of ferromagnetic substance in relation is arranged on the welding groove on the opposite side to the first welding underlay part. 4. Arc welding method according to one of claims 1 to 3, characterized characterized in that an auxiliary welding pad in the vicinity of the material to be welded and along the welding line is arranged, while the welding base part is kept largely isolated from the material to be welded is and where an electrical independent of the welding current —2 current flows through the welding pad. 3 09848 / 1Ö23 5. arc welding method according to claim 4, characterized in that that the auxiliary welding pad has a channel and is arranged in contact with the welding line, wherein the channel is arranged in the welding pad part and is along this extends. 6. Arc welding process for use in build-up welding according to one or more of the preceding claims, characterized in that an electrode has an insulating material is placed on the area to be built up that an auxiliary welding underlay part arranged on the back of the area to be built up largely isolated from the material to be built up and that an electric current through the auxiliary welding backing part flows that is independent of the welding current. 7. Arc welding process according to one or more of the preceding Claims, characterized in that the auxiliary welding support part is largely isolated from the material to be welded and an electric current flows through it which is independent of the welding current and that one of the auxiliary and welding currents is a direct current and the other a Alternating current is. 8. Arc welding method according to one or more of the preceding Claims, characterized in that a pair of auxiliary welding pads are arranged so that on each Side of the weld line such a part largely insulated from the material to be welded is provided that the auxiliary welding support parts of with respect to the flow direction opposite currents are flowed through, one of the auxiliary and welding currents being a direct current and the other is an alternating current. 9. Arc welding process according to one or more of the preceding Requirements for use in electric gas welding, since -3- 309848/1023 characterized in that on both sides of the welding groove in largely insulated, one auxiliary welding pad each is arranged, with the two welding pad parts are traversed by electrical currents in the opposite direction, during one of the welding and auxiliary currents through the welding pad parts is a direct current and the other is an alternating current » 10. Arc welding method according to one or more of the preceding Claims, characterized in that an alternating current is used as the welding current and that both sides the auxiliary welding support parts arranged in the welding groove are traversed by alternating currents of different phases. 11. Arc welding method according to one or more of the preceding Claims, characterized in that the by an auxiliary welding support member arranged along the welding groove auxiliary current flowing adjustable and to the welding condition is adjustable "to thereby provide control of the welding arc. 12. Arc welding method according to one or more of the preceding Claims, characterized in that the temperature is detected at the welding zone, the auxiliary current being automatic is controlled by the temperature detected during the weld. 309848/1023