Wheel Disc Manufacturing via Level-End Butt Welding and Radial Expansion
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Solution Overview
Problem
Existing methods for manufacturing wheel discs, such as those described in EP-1867408-A, JP-2005 000 967 A, and US 1 931 163 A, face challenges in butt welding and subsequent shaping operations, particularly in achieving uniform welds and managing radical shape changes from cylindrical to truncated-cone or annular sphere segments.
Innovation Solution
A method involving a strip of sheet metal is bent with end portions remaining level, butt welded on the same plane, followed by radial expansion to create a cone-shaped configuration, and then subjected to press-moulding operations to form an annular shell, with subsequent material removal and shaping to improve weld quality and alignment, reducing stress and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the starting strip of sheet metal is bent on its entire extension with arched end portions for butt welding, then a cylindrical ring can be formed, but the butt welding of end portions becomes problematic and difficult to achieve with uniform quality
Solution Approach 1:
The end portions of the strip are left level (unbent) before welding, creating a preliminary configuration that facilitates proper alignment and uniform butt welding. This preliminary action of not bending the entire strip allows the welding operation to be performed with consistent quality across the weld joint.
2Shape
If the cylindrical ring is directly subjected to radical press-moulding operations to shape it into truncated-cone or annular sphere segment, then the desired final shape is achieved, but the radical change of shape creates stress and wear problems
Solution Approach 1:
The shaping process is divided into multiple sequential stages: first forming a cylindrical ring with level ends, then progressively shaping through controlled press-moulding operations. This segmentation of the deformation process reduces stress concentration and wear by distributing the shape change across multiple controlled steps rather than one radical operation.
3Ease of manufacture
If the end portions of the strip are left level instead of bent, then bringing them together for welding is simplified and alignment is improved, but the challenge of forming the cylindrical ring shape remains
Solution Approach 1:
Different portions of the strip are treated differently: the central portion is bent to form the cylindrical shape, while the end portions are left level to facilitate welding. This local differentiation allows each region to serve its specific function - the bent central portion creates the ring geometry while the level ends enable easy alignment and uniform welding.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method simplifies the welding process, enhances weld quality, and reduces stress and wear by ensuring uniform alignment and surface matching, leading to improved mechanical characteristics and easier finishing operations.
Implementation Method 1
The strip of sheet metal 1 is then shaped: it is mainly bent, leaving however, that its end portions or limbs, indicated with 1a and 1b in figures 1 and 2, remain level
Implementation Method 2
The end faces of the limbs 1a and 1b of the strip 1 are brought together, and then welded, on substantially a same plane, so as to make a substantially cylindrical ring 2
Implementation Method 3
After the welding and the following accessory processes, but before the subsequent pressing and shaping operations, the ring 2 of figure 2 is subjected to a preliminary rounding operation through radial expansion with per se known tools
Implementation Method 4
The ring 2 is then subjected to press-moulding operations. In a first moulding operation the edge with the greatest diameter of the ring 2 is axially brought into abutment against a stop surface, so that the material of the ring is made to flow radially towards the centre
Data Source
Figure 1~2
Figure 3~5
Figure 6~8
AI summary
The method comprises the operations of: - providing a strip of sheet metal (1) substantially shaped like an elongated parallelogram with an essentially uniform thickness; - bending such a strip of sheet metal (1) and welding together the end portions (1a, 1b) so as to make a substantially cylindrical ring; and - subjecting the ring (2) to press-moulding and shaping operations through plastic deformation so as to give it a desired shape. The strip of sheet metal (1) is bent so that its end portions (1a, 1b) are level and such end limbs (1a, 1b) are brought together and butt welded substantially on a same plane, so as to obtain a ring (2) which has a chordal flattened wall portion (1a, 1b). Before undergoing the aforementioned prcss-moulding and shaping operations, the ring (2) is subjected to a preliminary rounding operation through radial expansion.