DE102014011111A1 - Apparatus and method for build-up welding - Google Patents

Abstract

Cladding (10) for overlay welding, in particular for MAG welding, plating or armoring with identical or higher value weld metal for protecting surfaces of workpieces (26) with at least one welding rectifier (18) and a wire feed box (11) which via a wire feed motor the welding wire ( 12) by a contact electrode (15a) depending on the Abschmelzleistung against the workpiece surface, wherein at least one additional wire feed box (22), a second welding wire (23) via a wire feed (24) in the arc (25) of the melting area (25a ) of the welding torch (15) and the melted, to be coated workpiece surface under a protective gas atmosphere.

Description

The present invention relates to a device and a method for build-up welding, in particular MAG welding, for the plating or tanks with similar or higher quality weld metal for the protection of surfaces of components.

For corrosion protection, Cr / Ni steels or nickel-based materials are welded onto unalloyed or low-alloy structural steel. For example, by contract welding bearing seats and liners are made on shafts for ship propellers from alloys that should have very good lubrication and emergency running properties. Such so-called. Cladding layers can be repaired in case of need also with relatively little effort.

As wear protection, even hard coatings up to 63 HRC are welded onto components, which can then be machined or only machined by grinding as required. Some types of hard armor are also not further processed, such. B. on crusher waves or tooth flanks.

For cladding mainly three welding processes are used. In addition to the highly efficient ESW process (electroslag welding, ie electro-slag welding), in addition to the TIG process (tungsten inert gas welding), MAG welding (metal active gas welding) with a welding focus under a protective gas atmosphere is used.

Although the known welding methods have proved successful, it has been found, in particular in the build-up welding, that the arc is much more concentrated in MAG welding in comparison with TIG hot-wire welding. For this reason, in the case of MAG welding, various measures must be taken to keep the segregation ("segregation") between the surface material to be processed and the welding wire used within the required limits. These include adjusting the burner position, welding position and welding speed.

This is disadvantageous, in particular in the case of larger build-up welding work, since setting the welding parameters is time-consuming and thus cost-intensive. These pure labor costs add to the actual tooling costs and the significant downtime costs that the welding machine can not produce.

It is therefore an object of the present invention to provide a device for an order welding process, with which the downtime is reduced, the order rate, the Abschmelzleistung and thus the manufacturing capacity is increased.

This object is achieved by the features specified in claim 1, in particular by at least one additional wire feed case, which brings a second welding wire via a wire feed in the melting area between the electrode and the melted, to be coated workpiece surface under a protective gas atmosphere in the welding focus.

According to one embodiment of the device according to the invention, the welding wire feed from the first wire feed box is synchronized with the second welding wire feed from the second wire feed case.

In a further embodiment, the second welding wire is introduced as a cold wire into the welding focus of the welding arc.

According to a particularly preferred embodiment of the present invention, it is provided that a wire preheating is assigned to the second welding wire, which is then introduced as a hot wire in the welding focus of the welding arc. The use of hot wire helps to improve the weld pattern.

By introducing a second welding wire in the welding arc of a welding gun more material can be melted. As a result, the job speed is significantly increased. At the same time, the second welding wire cools the melt produced during welding in a controlled manner so that the penetration depth of the mixing (melting between the welding wire and the material of the workpiece) in the workpiece is reduced.

In a further preferred embodiment, the wire preheating preheats the second wire with a current of 35 A to 140 A. The strength of the preheating depends, for example, on the wire size used and the material used. It is also dependent on the weld pattern and the predetermined limits of dilution.

In a further preferred embodiment, the device is adjusted so that the deposition rate of the first and second wires is between 4 and 10 Kg / h, preferably 9 Kg / h. Also conceivable are higher ablation rates, which then depend on the capacity or performance of the welding device used.

With the present device, a good balance is achieved between the application speed and the reflow performance on the one hand and the economy of the equipment on the other.

According to a further advantageous embodiment of the device according to the invention, a double-wire drive for the first wire and the second wire is attached to a feed motor, which then convey the two wires in parallel. As a result, the device could be made more compact. In a further embodiment, the second wire is introduced laterally from the welding torch into the focus of the welding arc and melted there.

Another object of the present invention is to provide an improved method of MAG welding.

This object is achieved by the features of the method steps according to claim 7, in particular by the fact that at least one additional wire feed case is provided, which introduces a second welding wire into the welding focus via a wire feed into the melting region between the electrode and the melted workpiece surface to be coated under a protective gas atmosphere ,

In one embodiment of the method according to the invention, it is provided that the welding wire feed from the first wire feed case is synchronized with the second welding wire feed from the second wire feed case.

According to a further embodiment of the method according to the invention, in a further step, the second welding wire is connected to a wire preheating, which acts on the welding wire with an electric heating current.

In a preferred embodiment of the method according to the invention, the welding wire is then introduced as a hot wire via a wire guide in the focus of the welding arc, where it is melted together with the first welding wire and the material of the workpiece.

Further advantageous measures are described in the subclaims. The invention is illustrated in the accompanying drawings and will be described in more detail below.

The single figure shows a schematic overall view of the device according to the invention in the working position, with an additional welding wire feed in a schematic representation of an inventive MAG welding system.

The welding system 10 Several components and ancillaries are assigned. This includes a wire feed motor (not shown), which in a first wire feed box 11 is arranged. The wire feed case 11 conducts a first welding wire 12 from a first storage drum 13 by means of the wire feed motor via a first wire feed 14 through a contact electrode 15a to a welding torch 15 , The conveying speed V _{D of} the first welding wire 12 can be with a wire feed case 11 assigned corrector 20 infinitely adjustable.

The welding torch 15 is via power supply 16 and 17 with a welding rectifier 18 electrically connected. The welding rectifier 18 Again, with the wire feed box 11 electrically coupled. This makes it possible to adjust the current to the first welding wire 12 to melt depending on the conveying speed V _D. This ratio can, depending on the material of the workpiece to be machined with a controller 21 be set variably.

Via a second wire feed case 22 becomes a second welding wire 23 from a second storage drum 19 unwound and over a second wire feeder 24 guided. The second wire feeder 24 are driving means 24a and / or proppants 24b downstream, with which the second welding wire 23 in the focus of the arc 25 to be led. In the arc 25 become the first welding wire 12 and the second weld 23 completely melted.

Because with MAG welding the arc 25 For this reason, various precautions have to be taken to keep the dilution within required limits. These include, among other things, the torch position, the welding position and the welding speed.

Because with MAG welding the arc 25 is very concentrated, various precautions have to be taken to keep the dilution (smoldering segregation) within required limits. This can be caused inter alia by the burner position, the welding position and the welding speed.

The mixture can also be cooled by the arc 25 generated melting area 25a to be controlled. For example, the second welding wire 23 as cold wire at the same current in the arc 25 be guided. The dilution and the penetration depth of the weld metal in the melting area 25a of the workpiece 26 can be varied.

In the present embodiment, the second welding wire is 23 a wire preheating 27 assigned. Through the wire preheating 27 the melting volume is significantly increased. This results in a much smoother surface of the workpiece 26 achieved and the difference between highs and lows of the side by side applied welds is reduced to a minimum.

The wire preheating 27 can be designed for example as a welding transformer. The welding wires 12 and 23 be by means of their respective assigned wire feeders 14 . 24 . 24a and 24b guided.

LIST OF REFERENCE NUMBERS

10

welding system

11

first wire feed case

12

first welding wire

13

first storage drum

14

wire feed

15

welding torch

15a

contact electrode

16

power

17

power

18

Rectifiers

19

second storage drum

20

proofreader

21

regulator

22

second wire feed case

23

second welding wire

24

wire feed

24a

drive means

24b

proppant

25

Electric arc

25a

melting region

26

workpiece

27

wire preheating

Claims (10)

Cladding, in particular for MAG welding, cladding or tanks with identical or higher quality weld metal for protecting surfaces of workpieces ( 26 ) with at least one welding rectifier ( 18 ) and a wire feed case ( 11 ) via a wire feed motor a welding wire ( 12 ) by a contact electrode ( 15a ) of a welding torch ( 15 ) as a function of the deposition rate against the workpiece surface, characterized by at least one additional wire feed case ( 22 ), which has a second welding wire ( 23 ) via a wire feed ( 24 ) in the melting area ( 25a ) between the welding torch ( 15 ) and the melted under an inert gas atmosphere to be coated workpiece surface. Apparatus according to claim 1, characterized in that welding wire feed from the first wire feed box ( 11 ) with the second welding wire feed from the second wire feed box ( 22 ) is synchronized. Apparatus according to claim 1 and 2, characterized in that the second welding wire ( 23 ) as a cold wire in the focus of the welding arc ( 25 ) can be introduced. Device according to claims 1 and 2, characterized in that the second welding wire ( 23 ) a wire preheating ( 27 ) and the second welding wire ( 23 ) as hot wire in the focus of the welding arc ( 25 ) can be introduced. Apparatus according to claim 4, characterized in that the wire preheating ( 27 ) the second welding wire ( 23 ) preheated with an electrical current of 35 A to 140 A. Device according to one or more of the preceding claims, characterized in that a double-wire drive for the first welding wire ( 12 ) and the second welding wire ( 23 ) is coupled to a feed motor and the two welding wires ( 12 . 23 ) are conveyed in parallel. Method for build-up welding, cladding or tanks with similar or higher quality weld metal for protecting surfaces of workpieces with at least one welding rectifier and a wire feed case via a wire feed motor drives the wire through a contact electrode in response to the Abschmelzleistung against the workpiece surface, characterized in that at least one additional wire feed case, which brings a second welding wire via a wire feed in the melting area between the electrode and the melted, to be coated workpiece surface under a protective gas atmosphere in the welding focus. A method according to claim 7, characterized in that the welding wire feed from the first wire feed box is synchronized with the second welding wire feed from the second wire feed case. A method according to claims 7 and 8, characterized in that the second welding wire is connected to a wire preheating, which acts on the welding wire with an electric heating current. A method according to claims 7 to 9, characterized in that the welding wire is introduced as a hot wire via a wire guide in the focus of the welding arc, where it is melted with the first welding wire and the material of the workpiece.

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