Joining Stud Surface Geometry for Thin-Sheet Arc Welding
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Solution Overview
Problem
The challenge of effectively joining studs to thin metal sheets, particularly aluminum, without damaging the sheet during the welding process is exacerbated by the trend towards lighter vehicle body panels, as traditional welding methods create local energy peaks that penetrate the sheet.
Innovation Solution
A joining stud design featuring a joining surface with alternating first and second protrusions of varying radial dimensions, allowing for a larger effective welding surface area and even energy distribution, suitable for drawn-arc stud welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional welding methods are used on thin metal sheets, then welding strength can be achieved, but the welding arc penetrates through the sheet causing damage
Solution Approach 1:
The joining surface features protrusions with varying radial dimensions (first protrusions with larger radial dimension, second protrusions with smaller radial dimension) arranged in an alternating pattern. This creates local variations in the welding surface that control energy distribution, ensuring adequate welding strength at protrusion peaks while preventing excessive energy concentration that would cause penetration damage in thin sheets.
Solution Approach 2:
The joining surface is segmented into multiple discrete protrusions rather than a continuous flat surface. This segmentation distributes the welding energy across multiple localized contact points, preventing the concentration of energy in a single area that would lead to through-penetration, while still achieving sufficient overall weld strength through the combined effect of all protrusions.
2Object-affected harmful factors
If the joining surface area is increased to distribute welding energy, then penetration is prevented, but the effective welding surface area is reduced due to protrusion spacing
Solution Approach 1:
By creating protrusions with varying radial dimensions, the invention optimizes the effective welding surface area within the constraints of the overall joining surface area. The alternating pattern of larger and smaller protrusions ensures adequate spacing to prevent penetration while maximizing the cumulative surface area available for welding energy distribution.
3Ease of manufacture
If protrusions with uniform radial dimensions are used, then manufacturing is simplified, but energy distribution across the joining surface becomes uneven
Solution Approach 1:
The invention deliberately introduces asymmetry by providing protrusions with two different radial dimensions (first protrusions with larger radial dimension, second protrusions with smaller radial dimension). This asymmetric design optimizes energy distribution across the joining surface, creating a more uniform energy profile during welding compared to uniform protrusions, while remaining manufacturable through standard forming processes.
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
The design facilitates strong, uniform welding joints on thin metal sheets, preventing penetration and ensuring high strength against torsional loads, while being compatible with drawn-arc stud welding processes.
Implementation Method 1
a stud welding process includes drawing an electric arc between the joining surface of the welding stud and the sheet metal to melt the joining surface and an upper surface portion of the sheet metal
Implementation Method 2
it is possible to arrange a relatively high number of protrusions on the joining surface, which each have a certain radial length or dimension. This allows to increase the effective welding surface area
Data Source
Figure 1
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AI summary
A joining stud (10) for joining to a workpiece (11), comprising an axially extending shaft portion (12) and a head portion (14) connected to the shaft portion (12) at one axial end thereof, wherein the head portion (14) has a joining surface (22) located essentially in a plane transverse to the longitudinal axis (16) of the shaft portion (12), wherein the joining surface (22) comprises a plurality of first protrusions (44) and a plurality of second protrusions (46), wherein the first protrusions (44) each have a first radial dimension (R1) and the second protrusions (46) each have a second radial dimension (R2), and wherein the first radial dimension (R1) is larger than the second radial dimension (R2).