Telescopic Crane Boom Section Welding Joint Relocation
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Solution Overview
Problem
Conventional telescopic crane boom sections face high stress concentrations at the welding joints located at the upper or lower ends, leading to stringent quality requirements for reliable performance, and manufacturing challenges due to the conventional location of these joints on the plane of symmetry.
Innovation Solution
A telescopic crane boom section design with a welding joint positioned at the edge of a lateral wall intersecting the neutral layer, allowing for reduced stress on the joint and incorporating planar upper and lower wall portions perpendicular to the symmetry plane for efficient load distribution using horizontal sliding elements, enhancing stiffness and manufacturing ease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the welding joint is located at the upper or lower end of the crane boom section on the plane of symmetry, then the manufacturing process is simplified, but the stress concentration at the welding joint increases leading to stringent quality requirements
Solution Approach 1:
The patent applies asymmetry by moving the welding joint from the symmetric upper or lower end positions to an asymmetric position at the edge of a lateral wall intersecting the neutral layer. This asymmetric relocation reduces stress concentration while maintaining manufacturing feasibility, resolving the contradiction between ease of manufacture and welding joint reliability.
Solution Approach 2:
The patent applies local quality by specifically positioning the welding joint at the lateral wall edge where the neutral layer intersects, rather than uniformly at the ends. This localized positioning exploits the stress distribution characteristics at that specific location to reduce stress concentration, thereby improving welding joint reliability without compromising overall manufacturing simplicity.
2Ease of manufacture
If the welding joint is located at the upper or lower end on the plane of symmetry, then manufacturing is easier, but high tensile or compressive stresses act on the welding joint requiring very high quality
Solution Approach 1:
The patent uses asymmetry to relocate the welding joint from the symmetric end positions (subject to high tensile or compressive stresses) to an asymmetric position at the lateral wall edge intersecting the neutral layer. This reduces the stress magnitude acting on the welding joint, thereby improving strength requirements while maintaining manufacturing ease.
Solution Approach 2:
The patent applies parameter changes by altering the spatial coordinates of the welding joint from end positions to lateral wall edge positions. This parameter change (location) exploits the stress distribution field characteristics to minimize stress exposure, thereby improving welding joint strength without sacrificing manufacturing ease.
3Strength
If planar upper and lower wall portions are added perpendicular to the symmetry plane, then load distribution and stiffness are improved, but the structural complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the boom section into distinct wall portions (upper, lower, lateral) with specific functional assignments. The planar upper and lower wall portions are segmented as separate structural elements that work together with the lateral walls to distribute loads, improving strength while keeping each segment relatively simple in form.
Solution Approach 2:
The patent applies local quality by adding planar wall portions specifically at the upper and lower regions perpendicular to the symmetry plane, where load distribution is most needed. This localized structural enhancement improves load distribution and stiffness without making the entire structure complex, as only specific regions are modified.
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 new design reduces stress on the welding joint, improves reliability, and allows for efficient and cost-effective production while maintaining high strength and stiffness, enabling effective load distribution and stress management in the crane boom sections.
Implementation Method 1
opposite longitudinal edges of the metal sheet are joined to each other by a welding joint extending in the longitudinal direction of the tubular beam
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A telescopic crane boom section having an elongated main body in the form of a straight tubular beam (30), which is formed by one single bent metal sheet and consists of wall portions (W1-W12) connected to each other via bending corners (33), wherein: - a neutral layer (37) of the tubular beam extends across lateral wall portions (W1, W2) on either side of a vertical plane of symmetry (36) of the tubular beam; - the tubular beam has planar upper and lower wall portions (W3, W8), which are perpendicular to the vertical plane of symmetry and connected to each one of said lateral wall portions via intermediate wall portions; and - opposite longitudinal edges of the metal sheet are joined to each other by a welding joint (35) located at an upper or lower edge of one of said lateral wall portions. The invention also relates to a crane boom and a crane comprising such a crane boom section.