Method of automatically setting a welding parameter for MIG/MAG welding and a controller for performing the method

1. A method of automatically setting a welding parameter of a welding apparatus for MIG/MAG welding comprising:

initiating, by a welding controller of the welding apparatus, a parameter setting welding operation;

detecting, by the welding controller, a response welding current and a present wire feed speed during said parameter setting welding operation;

collecting, by the welding controller, the response welding current and present wire speed as a plurality of data couples, wherein a given data couple of the plurality of data couples defines an operating point in a welding current/wire feed speed space;

identifying, by the welding controller, a first function mapping a welding current to a wire feed speed from said response welding current and said present wire feed speed, the identifying comprising comparing the plurality of data couples to a set of stored functions including the first function, wherein the first function best represents the plurality of data couples;

determining, by the welding controller, a desired welding current; and

determining, by the welding controller, a desired wire feed speed from said first function and said desired welding current.

2. The method according to claim 1 , further comprising

setting, by an operator of the welding apparatus, an actual thickness of a work piece to be welded; and

determining, by the welding controller, said desired welding current from said set actual thickness of the work piece.

3. The method according to claim 2 , wherein said first function forms a linear mapping.

4. The method according to claim 3 , wherein said linear mapping is expressed as v=k*I p , where v is the wire feed speed, I the current and p is a value between 1 and 2.

5. The method according to claim 1 wherein said parameter setting welding operation comprises establishment of a short arc welding process defined by a short-circuiting time and an arc time, and controlling the melting efficiency of the electrode so that the melting efficiency is increased when a ratio of a measured short-circuiting time and a total period time, where the period time is a sum of the short-circuiting time and the arc time, exceeds a defined adjustable set value, and the melting efficiency is decreased when said ratio goes below said set value.

6. The method according to claim 5 , further comprising determining a voltage reference value U ref from said ratio.

7. The method according to claim 6 , further comprising determining, by the welding controller, a globular area transition current from said determined wire welding material.

8. The method according to claim 7 , further comprising adjusting, by the welding controller, a short-circuiting percentage from a first larger value to a second smaller value when said desired welding current is increased to a value equal or greater than said globular area transition current, and by adjusting said short-circuiting percentage of the period time from a first smaller value to a second larger value when said desired welding current is decreased to a value equal or smaller than said globular area transition current.

9. The method according to claim 5 further comprising:

measuring, by the welding controller, a welding voltage and retrieving a parameter representing the wire feed speed during said parameter setting welding operation; and

identifying, by the welding controller, a second function mapping said parameter representing the wire feed speed to said welding voltage from said measured welding voltage and said retrieved parameter.

10. The method according to claim 9 , further comprising:

determining, by the welding controller, a second welding parameter depending on wire welding material from said second function.

11. The method according to claim 9 , further comprising

determining, by the welding controller, a wire welding material from said second function.

12. The method according to claim 11 , wherein said desired welding current is determined from said set actual thickness of the work piece in dependence of said wire welding material determined from said second function.

13. The method according to claim 1 , further comprising selecting, by an operator of the welding apparatus, a work piece thickness, automatically determining, by the welding controller, the desired welding current, the desired wire feed speed, and a voltage reference value from data collected during the parameter setting welding operation and performing, by the welding controller, a continued welding process with the desired welding current, the desired wire feed speed, and the voltage reference value as control parameters.