US 11,666,982 B2
Method and device for providing a referenced distance signal for controlling the position of a welding torch
Dominik Söllinger, Pettenbach (AT); Andreas Hummelbrunner, Pettenbach (AT); and Wilhelm Ortbauer, Pettenbach (AT)
Assigned to Fronius International GmbH, Pettenbach (AT)
Appl. No. 16/642,148
Filed by Fronius International GmbH, Pettenbach (AT)
PCT Filed Aug. 31, 2018, PCT No. PCT/EP2018/073493
§ 371(c)(1), (2) Date Feb. 26, 2020,
PCT Pub. No. WO2019/043168, PCT Pub. Date Mar. 7, 2019.
Claims priority of application No. 17189020 (EP), filed on Sep. 1, 2017.
Prior Publication US 2020/0306862 A1, Oct. 1, 2020
Int. Cl. B23K 9/095 (2006.01); B23K 9/12 (2006.01); B23K 37/02 (2006.01); B25J 13/08 (2006.01)
CPC B23K 9/0953 (2013.01) [B23K 9/0956 (2013.01); B23K 9/126 (2013.01); B23K 37/0258 (2013.01); B25J 13/087 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method for providing a referenced distance signal, which corresponds to the distance between a contact tip of a welding torch and a workpiece to be machined, comprising the steps of:
(a) adjusting an operating point on a predetermined welding characteristic which is defined at least by a wire feed rate, a welding voltage and/or a welding current, and a contact-tip-to-work distance (CTWD) between a contact tip of the welding torch and the workpiece to be machined;
(b) reading out or determining a target parameter value of at least one parameter dependent on the CTWD for the operating point set on the welding characteristic;
(c) determining an actual parameter value of the parameter dependent on the CTWD by measuring at least one of the present welding parameters of wire feed rate, welding voltage or welding current;
(d) modifying the determined actual parameter value as a function of a calculated difference between the target parameter value and a predetermined reference value which is in the middle of an output value range of the referenced distance signal, wherein the determined actual parameter value is modified either - (a) by adding the difference between the target parameter value and a reference value onto the determined actual parameter value as an offset, or (b) by multiplying the actual parameter value by a correcting factor which is determined as a function of the difference between the target parameter value and the reference value; and
(e) outputting the referenced distance signal, corresponding to the modified actual parameter value, as a seam track signal to a robot control unit during the welding process for regulating a position of the welding torch coupled to a robot arm, the position of the welding torch being modified by means of the robot arm in such a way that the output value of the referenced distance signal is changed to the predetermined reference value so as to maintain a desired CTWD.