Multi-Thickness Welded Vehicle Rail With Uniform Weld Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for manufacturing vehicle rails with varying strength requirements using metallic tubes face challenges such as increased weight and cost with uniformly thicker tubes, and potential weaknesses in butt-jointed welds between tubes of different thicknesses.
Innovation Solution
A process involving the welding of metallic tubes with different wall thicknesses but the same outer diameter, followed by preheating to achieve a uniform crystalline structure, and then blow forming and quenching to create a rail with uniform material strength across the weld, using MAG welding and thermomechanical processing to minimize the Heat Affected Zone's negative effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a uniformly thicker tube is used to meet strength requirements in high-stress areas, then the strength is improved, but the weight of the vehicle increases
Solution Approach 1:
The patent applies local quality by using tubes with different wall thicknesses in different sections of the rail. High-stress areas (between A and B pillars) use thicker-walled tubes for maximum strength, while lower-stress areas use thinner-walled tubes to reduce weight. This localized differentiation optimizes the strength-to-weight ratio throughout the rail structure.
Solution Approach 2:
The rail is segmented into multiple tube sections with different wall thicknesses rather than using a single uniform tube. The rail consists of at least two tubes of different wall thicknesses joined together, allowing each segment to be optimized for its specific structural requirements while maintaining overall rail integrity.
2Strength
If a uniformly thicker tube is used to meet strength requirements, then the strength is improved, but the manufacturing cost increases
Solution Approach 1:
Instead of manufacturing an expensive uniformly thick tube, the patent uses local quality by applying thicker walls only where structurally necessary. This reduces material costs while maintaining the required strength in critical areas, making the rail more cost-effective to manufacture.
Solution Approach 2:
The rail is divided into segments that can be manufactured separately with appropriate wall thicknesses and then joined. This segmentation allows for more efficient material usage and reduces overall manufacturing cost compared to producing a single thick-walled tube throughout.
3Ease of manufacture
If tubes of different thicknesses are butt-jointed together, then the manufacturing cost is reduced, but the weld strength and reliability are compromised
Solution Approach 1:
The patent employs a nested joint configuration where one tube is inserted into the other at the junction, creating an overlapping joint rather than a simple butt joint. This nesting approach provides multiple weld lines and increases the effective weld area, significantly improving joint reliability while maintaining cost-effectiveness.
Solution Approach 2:
The patent combines multiple tubes of different wall thicknesses into a single integrated rail structure through welding. The overlapping joint design merges the tubes in a way that creates redundant weld paths, enhancing the reliability of the connection while keeping manufacturing costs lower than a uniform thick tube.
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 process results in a vehicle rail with improved strength uniformity and cost-effectiveness, reducing material usage and weight while avoiding the weaknesses associated with traditional butt-welded joints.
Implementation Method 1
molding the tube blank at an elevated temperature by expanding the tube blank against the inner molding walls of the molding tool by injecting a pressurized medium into an interior cavity of the tube blank
Implementation Method 2
quenching the tube blank by replacing the pressurized medium with a cooling medium through the molding tool and the tube blank to achieve a rapid cooling effect on the tube blank
Implementation Method 3
welding the first tube and the second tube together to form a weld at the joint to form a tube blank with a heat affected zone of lower metal strength in the area of the weld
Data Source
AI summary
A process for preparing a multi-thickness welded steel vehicle rail, the process comprises the steps of: (a) forming a first tube having a first outer diameter, an inner diameter and a first wall thickness; (b) forming a second tube having the first outer diameter, a second inner diameter and a second wall thickness different than the first wall thickness; (c) swaging a first end of the first tube to a second outer diameter less than the second inner diameter of the second tube; (d) inserting the swaged first end of the first tube into an end of the second tube to form a joint; (e) welding the first tube and the second tube together to form a weld at the joint to form a tube blank with a heat affected zone of lower metal strength in the area of the weld; (f) preheating the tube blank to create a common crystalline microstructure along a length of the tube blank; (g) introducing the tube blank into a blow molding tool having inner molding walls; (h) molding the tube blank at an elevated temperature by expanding the tube blank against the inner molding walls of the molding tool by injecting a pressurized medium into an interior cavity of the tube blank; and (i) quenching the tube blank by replacing the pressurized medium with a cooling medium through the molding tool and the tube blank to achieve a rapid cooling effect on the tube blank and to create a completed vehicle rail with essentially uniform material strength across the weld. A completed vehicle rail has an overlapped welded structure and uniform microcrystalline structure along the length of the rail.