Method of production of workpieces by welding equipment

A method of free-shape welding a Pelton wheel bucket on a hub, the method comprising the steps of determining a base-outline for the bucket on the hub;

• positioning a weld head proximate the hub;
• moving the hub relative to the weld head within the bucket base-outline;
• activating the weld head for weld-depositing metal on the hub and thereby forming a first metal layer thereon having the shape of the base-outline;
• thereafter moving the weld head and the hub relative to each other generally transversely to the first metal layer;
• determining another outline of the bucket;
• moving the hub relative to the weld head within the other bucket outline;
• weld-depositing metal on top of the first metal layer to form a second metal layer on top of the first metal layer;
• and repeating the steps of determining, moving the hub relative to the weld head, and weld-depositing metal on top of previously formed metal layers to thereby finish form the bucket, the step of moving for at least one of the metal layers including the step of tilting the hub relative to the weld head to angularly incline a top surface of a most recently formed metal layer relative to a horizontal plane, and the step of weld-depositing comprising the step of weld-depositing metal on top of said most recently formed metal layer so that the layer being deposited forms a top surface lying in a substantially horizontal plane.

A method of free-shape welding to form a rotationally asymmetric workpiece of any desired shape comprising the steps of:

• providing a foundation body defining a welding surface for forming the workpiece thereon;
• determining a two-dimensional base outline for the workpiece;
• positioning a weld head proximate the welding surface, the weld head being adapted to form a bead of welded metal on the weld surface;
• moving the foundation body and the weld head relative to each other within the confines of said workpiece outline and simultaneously activating the weld head to deposit said metal bead on the welding surface of the foundation body until a first metal layer with a shape of the base-outline has been formed on the welding surface;
• and
• depositing at least one additional layer of metal over the first metal layer by
• (i) determining an additional outline and a relative position for the additional metal layer from the desired shape of the workpiece;
• (ii) activating the weld head to deposit by metal electrode inert gas (MIG) welding a further weld bead on the first metal layer;
• and
• (iii) moving the foundation body relative to the weld head so that the further weld bead is deposited on the first layer within and at the relative position of the additional outline only;
• whereby the finished workpiece will have the desired rotationally asymmetric, three-dimensional shape.

A method of free-shape welding to form a rotationally asymmetric workpiece of any desired shape by depositing successive metal layers on top of each other comprising the steps of:

• (a) computer modelling a three-dimensional shape for the workpiece including establishing a planar, two-dimensional base-outline for the workpiece and the shapes and relative positions for all additional metal layers to be deposited on top of each other to form the desired workpiece;
• providing a foundation body including a welding surface;
• providing a weld head for depositing a bead of metal by welding;
• providing robot means operatively coupled with the foundation body and the weld head for three-dimensionally moving the body of the bead with respect to each other;
• and
• activating the robot means to initially move the welding surface relative to the weld head within the base outline of the workpiece while energizing the weld head to deposit by metal electrode inert gas (MIG) welding a weld bead until a first metal layer is formed on the welding surface in the shape of the base outline, and thereafter to move the foundation body and the weld head relative to each other while continuing to energize the weld head to deposit weld beads on the first layer to form all additional metal layers with the predetermined outlines and at the relative positions;
• whereby the workpiece of the desired shape is obtained following completion of a last metal layer.

Apparatus for free-shape welding a rotationally asymmetric workpiece of any desired shape comprising:

• a workpiece holder including means for holding a foundation plate;
• a metal electrode inert gas (MIG) weld head positioned proximate the foundation plate for depositing a metal in liquid form on the foundation plate;
• modelling means for generating a plurality of outlines for the workpiece so that all outlines together define the shape of the workpiece;
• and
• robot means operatively coupled with the work table and the weld head for three-dimensionally moving the foundation plate and the weld head relative to each other, the robot means being further operatively coupled with the modelling means for guiding relative movements between the foundation plate and the weld head along paths wholly contained within said outlines to deposit weld beads on the foundation body which are wholly contained within said outlines and which sequentially form a first metal layer on a welding surface of the foundation body and all additional metal layers, one on top of the other;
• whereby, upon the completion of a last layer, a workpiece having the desired rotationally asymmetric, three-dimensional shape is formed.