A preheating method for preheating a first component and a second component or a stack of welded components by a preheating arrangement for a welding device having an upper tool mounted to an upper support and a lower tool mounted to a lower support, wherein the upper and the lower support are movable relative to each other between an initial position and a welding position, and the preheating arrangement comprises:
- a. a preheating device defining a first plane by means of a first centerline extending along a first axis X and a second centerline extending along a second axis Y being perpendicular to the first axis X and
- b. the preheating device has a first side with a first preheating structure and an opposite second side with a second preheating structure, wherein
- c. the first preheating structure is asymmetric with respect to the first and/or the second centerline so that the respective axis is an axis of asymmetry, and
- d. the second preheating structure corresponds to the first preheating structure and is oriented like the first preheating structure such that, when viewed along a third axis Z perpendicular to the first plane, the first and the second preheating structure are arranged one above the other, wherein
- e. the preheating arrangement comprises further a first rotating means for rotating the preheating device between a first position and a second position such that the preheating structures in the first position have a first orientation and in the second position a second orientation
- e1. in which they are rotated around the axis of asymmetry by 180° compared to the first orientation or
- e2. in which they are rotated by an angle α in the range of 0°<α<360° around the third axis Z compared to the first orientation, wherein
- the first component comprises on a first side a first welding structure and on an opposite second side a second welding structure, the first and the second welding structure being formed congruent with the first and the second preheating structure of the preheating device and oriented such that the first welding structure and the second welding structure are rotated with respect to each other around the axis of asymmetry by 180° or around the third axis by the angle α, and
- the second component or the stack of welded components comprises at the side facing the first component a third welding structure which is oriented such that, when viewed along the third axis Z, the third welding structure is arranged above the welding structure of the first component facing the second component or facing the stack of welded components, wherein the preheating method comprises the steps of:
- a. moving the preheating arrangement from a parking position into a preheating position between the upper and the lower tool of a welding device, wherein the preheating device of the preheating arrangement is arranged in the first position having the first orientation in which the preheating structures overlay the welding structures in the preheating position, when viewed along the third axis Z, and an upper support as well as a lower support of the welding device are arranged in the preheating position each in a plane parallel to the first plane,
- b. preheating the first component and the second component or the stack of welded components, and
- c. moving the preheating arrangement from the preheating position into the parking position.