DD276831A1 - METHOD FOR THE UNIVERSAL VERTICAL UPWARD ARC BZW. PLASMA WELDING - Google Patents

Abstract

The invention relates to a method for single-layer vertical Aufwaerts arc or plasma welding of components and sheets of medium thickness s, preferably in thickness ranges of 3 to 15 mm, with I-seam preparation or very steep seam edge, with conventional power sources and vertical or Nearly vertical supply of wire electrodes, which requires substantially less energy without increasing the preparation and additional material required for I-seams compared with the known methods of this type. According to the invention, the object is achieved by the gap width bSp of the I-joint according to the relationship bSp (0.15 ... 0.3) s (0.9 ... 1.2) and the welding speed VS according to the relationship VS2 , 6 ... 3,2 / i4,8, where i is the current density in A / mm2, is selected.

Description

Explanation of the essence of the invention

The invention is based on the object d ^! e known vertical Aiifwärts-arc or plasma welding process to change such that it is possible, a vo. · V. - To keep it wire electrode outgoing arc within the narrow I-joints or V-joints with steep seam

According to the invention, the object is achieved in that the gap width b _{sp of} the I-joint according to the relationship

b _S p = (0.15 ... 0.3) s + (0.9 ... 1.2), where s is the thickness of the sheets to be welded, and the welding speed v, according to the relationship

2.6 ... 3.2 V ₅ = + 4.8,

where i is the current density in A / mm ² .

The feed rate of the wire electrode V ₀ is in a known manner depending on the welding speed v _s , the joint surface Ap and the Fλ- surface of the wire electrode Aq according to the relationship

Vp _K Ac v, A ₀

where K is a correction factor that characterizes weld peaking and is generally 1.05 to 1.1. For a favorable process control, it has been found that the distance between the wire electrode and joint flank not much larger than 1.5mm to choose.

As a result of lengthy and complicated investigations, it has been shown that in the single-layered I-seam welding only within the ranges given for gap and welding speed according to the invention a balanced relationship between molten base material and amount of molten wire per unit time and the amount required to fill the joint per unit time , so that the molten bath can be kept in the joint without additional means. This would allow advantageous vertical upward welding to be applied in the industry's thickness ranges of between 3 and 16mm without front weld pool protection. Another advantage of the invention is the significantly reduced energy requirements compared to the known vertical up welding methods. It was reduced by changing the heat transfer to the extent absolutely necessary for melting the wire electrode and melting the base material. As a result, the base material is thermally much lower than previously charged, so that the heat influence of the edge zones is reduced and the formation of the coarse grain zone is substantially kleinor. As a result of the resulting faster cooling, a refined primary grain also forms in the weld seam, thereby improving the mechanical-technological quality of the welded joint. Overall, the reduced heat input, without further heat treatment (normalization), ensures a notch impact strength two to three times higher than conventional values.

Very advantageous in the inventive solution, the small seam volume, the approximately parallel seam edges and the low heat input affects the welding behavior of the components to be welded. The shrinkage values are much lower than similar methods, so that often additional reworking (straightening of the components) can be omitted.

The low heat input, the favorable heat conduction and the resulting altered crystallization conditions allow even with an inner seam shape ratio substantially less than 1 weld-free seams to weld. The usual pronounced midrib as a weak zone in the middle of the seam is eliminated.

embodiment

The invention description will be explained using the example of the MAG vertical upward narrow gap welding, wherein

Fig. 1: Welding arrangement for the vertical upward arc welding with consumable electrode, Fig. 2: Principle of the welding process in the gap

represent.

When melting the joint edges 2 of the arc 3 burns left and right at the joint edge or both at the same time.

so that can be spoken by 1 or 2 arcs. (Fig. 1)

Dor arc wanders back and forth in the joint 1 and melts them at a great depth almost uniformly. In this case, however, only ⁷ h to ³ A of the Fugentiefo were recorded. The remainder is melted by the running melt 7 or the liquid weld metal, dio or which can thus be used for the welding process.

Dio electrode 5 is continuously and at an angle of otwa 90 ° to the plate 4 continuously cior joint supplied (Fig. 2). The droplet 8 passes by means of a short circuit into the material surface of the molten bath 7. The base material melted by the arc runs downwards by gravity. The remaining liquid layer between the arc and solid base material is minimized, which extremely improves the heat flow and the melting process of the base material.

Underneath the electrode, the melt pool is held in the narrow gap by the capillary action and the interfacial tension and thus forms the seam 6. Compared with conventional vertical welding technologies, a forced forming is not absolutely necessary. Only wurzolseitig a Schmelzbadsicherung is used to prevent any shooting through of the electrode.

Claims (2)

A method for vertical-upward arc plasma welding of medium thickness sheets with I-seam preparation or very steep seam flank, in which a wire electrode is guided parallel in the fugs from the seam bottom up, one of the wire electrode to the molten bath and / or the upper base metal over the surface of the molten bath extending arc is generated and the molten electrode material is drop-shaped into the underlying base metal-side molten bath, characterized in that the gap width bsp of the I-joint according to the relationship bsp = (0yi5 ... 0.3) s + (0.9 ... 1.2), where s is the thickness of the sheets to be welded, and the welding speed v _s is the relationship v _s ^ MW +4.8. where i is the current density in A / mm ² . 2. The method according to claim 1, characterized in that the distance between the wire electrode and joint flank is not chosen substantially greater than 1.5 mm. For this 2 pages drawings Field of application of the invention The invention relates to a method for single-layer vertical Aufwär ^ arc welding or plasma welding of components and sheets of medium thickness, preferably in thickness ranges of 3 to 16mm, with I-seam preparation or very steep seam edge, with conventional power sources and vertical or Almost vertical supply of wire electrodes. Characteristic of the known state of the art In order to reduce the expenditure of energy, additional materials and welding time, it has already been attempted, single-layered sheet thicknesses, ie in one operation to connect with each other. In DE-OS 2611246 a vertical-upward arc welding method is described in which a strip electrode is fed almost perpendicularly to a V-shaped weld joint. A slip shoe sliding at the front of the weld prevents leakage of liquid metal from the weld. The Schweißun _v i is performed by a generated by the strip electrode to the molten bath and / or the upper base metal burning arc, wherein the weld joint space widened and at the same teardrop shape passes the molten metal in the underlying base material-side molten bath. Due to the technologically induced V-seam, this technical solution requires a considerably higher preparation effort compared with I-seams and correspondingly much filler material for filling this large seam, so that this solution does not require a band electrode. To melt this band electrode and to melt the opposite of an I-seam joint surface is still a relatively high energy requirement is required. Despite the intended I-seam and the wire electrode used, the process for arc plasma welding described in DD-PS 120605, which also involves welding with an upwardly moving electrode, is still very energy-intensive. This is due to the fact that the anode and / or Katodenfall in which the highest energy conversions are located outside the Schweißfugo, since the parts to be connected during the welding process are not energized, but the arc between the burner with abschmelzender electrode and a non-consumable auxiliary electrode burns. Object of the invention Ziol of the invention is a Verfahron uinlagigen vertical-upward arc or plasma welding, which orlordort without increasing dos for I-Nähto urforderlichen preparatory sowio Zusatzarbeitstoffaufwandos compared to the known methods of this kind much victorious Enorgio.