Shielding gas device for stud welding with directed gas flow for stabilizing the weld pool

Abstract

(Main claim) Shielding gas device (Fig. 1) for stud welding, comprising a housing (4.) for enclosing the welding area. It is characterized in that a gas distribution pipe (3.) is arranged inside the housing, which has a plurality of outlet bores (5.), wherein the shielding gas is guided through the gas distribution pipe (3.) directly into the area of ​​the stud welding and only exits from the outlet bores (5.) in the immediate vicinity of the welding point.

Description

1. Technical field

[0001] The invention relates to a shielding gas device for stud welding, in particular for arc stud welding in metallic shipbuilding, offshore applications and similar applications with increased requirements for corrosion resistance and weld quality. 2. State of the art

[0002] In conventional stud welding with a ceramic ring, a gap is inherently present in the transition area between the stud shank and the weld bead. This gap promotes crevice corrosion, especially when used in the exterior areas of ships or in saline atmospheres.

[0003] A complete coating of this area with corrosion protection is only possible to a limited extent due to its geometry. To prevent corrosion, the transition area is often subsequently smoothed and sealed using TIG welding. This additional process leads to increased time and costs.

[0004] Furthermore, the ceramic ring must be mechanically removed after the welding process. The resulting residues cause additional cleaning and disposal costs.

[0005] In conventional shielding gas devices, the shielding gas typically flows into the device from above, displacing the oxygen to the outside. This creates turbulence that impairs the stability of the shielding gas atmosphere.

[0006] Particularly in the PC welding position (transverse position, horizontal welding on a vertical wall), the molten weld metal is not sufficiently stabilized. It tends to flow downwards due to gravity. This problem is exacerbated with larger stud diameters.

[0007] Therefore, reliable stud welding under shielding gas is currently only possible to a limited extent in certain welding positions. 3. Technical problem underlying the invention

[0008] The invention is based on the objective of providing a protective gas device which • a low-turbulence shielding gas flow enables, • the sweat bath is stabilized, especially in a transverse position, • prevents the liquid welding material from flowing away, • minimizes or prevents the formation of a corrosion-critical crack and • makes the ceramic ring and subsequent processing steps unnecessary. 4. Solution to the task

[0009] The problem is solved by a protective gas device with the features of claim 1.

[0010] The inert gas device according to the invention has a gas distribution tube (3) within its housing (4), which is provided with a plurality of defined outlet bores (5). The housing / support tube (4), the rubber holder (2), the gas distribution tube (3), and the end plate (6) are connected to one another via a base plate (7). A bellows (1) is mounted above the rubber holder (2) to seal the inert gas device against the atmosphere at the movable bolt holder (not shown in the drawing).

[0011] The shielding gas is connected via a gas connection (8.) in the base plate (7.). Through the gas connection (8.) and the base plate (7.), the shielding gas is guided into the space between the housing (4.) and the gas distribution pipe (3.) directly to the area of ​​the stud weld and only escapes in the immediate vicinity of the weld point.

[0012] This achieves the following: • no large-scale mixing of protective gas and oxygen occurs within the device, • Turbulence should be avoided, • the protective gas atmosphere is specifically built up at the welding point, • the weld pool is stabilized by directed gas flow.

[0013] The gas distribution pipe (3.) is preferably designed to be interchangeable, so that different hole patterns (5.) or flow directions can be used for different welding positions. Depending on the application, the hole pattern (5.) has a different number, angle, and spacing of holes.

[0014] The end plate (6.) of the housing (4.) is interchangeable for the different welding positions (e.g., PA or PC). For the PC welding position, the end plate (6.) is fitted with degassing slots on one side ( Fig. 2) designed to actively stabilize the liquid weld metal through the directed shielding gas flow, thereby reducing or preventing flow due to gravity.

[0015] For welding position PA, the end plate (6.) is fitted with degassing slots running all around ( Fig. 3) carried out to ensure that the liquid weld metal is evenly distributed around the bolt to be welded by means of uniform degassing. 5. Advantageous effects of the invention

[0016] The protective gas device according to the invention offers in particular the following advantages: • Elimination of the ceramic ring • No need to remove ceramic residue • Uniform, fillet-seam-like weld bead • Avoiding a gap between the bolt shank and the weld bead • Subsequent TIG rework is partially or completely eliminated • Time and cost savings • Improved corrosion resistance • Process reliability even with larger bolt diameters Reference symbol list 1 bellows 2 rubber holders 3 Gas distribution pipe 4 cases 5-hole (hole pattern) 6 End plate ( Fig. 2 & Fig. 3) 7 Base plate 8 Gas connection

Claims

[1] (Main claim) Shielding gas device ( Fig. 1) for stud welding, comprising a housing (4.) for enclosing the welding area. It is characterized in that a gas distribution pipe (3.) is arranged inside the housing, which has a plurality of outlet bores (5.), wherein the shielding gas is guided through the gas distribution pipe (3.) directly into the area of ​​the stud welding and only exits from the outlet bores (5.) in the immediate vicinity of the welding point. [2] Shielding gas device ( Fig. 1) according to claim 1, characterized by , that the gas distribution pipe (3.) is designed to be replaceable. [3] Shielding gas device ( Fig. 1) according to any one of the preceding claims, characterized by , that the outlet bores (5.) are arranged and angled in such a way as to generate a directed gas flow to stabilize the liquid weld metal. [4] Shielding gas device ( Fig.1) according to any one of the preceding claims, characterized by that the gas flow is provided by an interchangeable end plate (6.), which ensures optimal stabilization of the weld metal depending on the welding position. In the PC welding position, the end plate (6.) is designed as follows ( Fig. 2) that flow of the weld metal against the direction of gravity is reduced or prevented. In welding position PA, the design ( Fig. 3) designed so that the weld metal is perfectly distributed around the bolt to be welded. [5] Use of a shielding gas device according to any one of claims 1 to 4 for stud welding without the use of a ceramic ring.

Images