One-Piece Traction Rod for Crane Jib Bracing
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Solution Overview
Problem
Weld connections in traditional traction rods for crane jibs are prone to fatigue crack formation due to notch sensitivity, reducing their fatigue strength and increasing the risk of early failures under dynamic stress, leading to high costs.
Innovation Solution
A one-piece tubular construction with wall thickening at the ends, achieved through processes like hot upsetting, overlay welding, or sintering, ensuring a notch-free and projection-free transition to enhance fatigue strength and load-bearing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welded traction rods with fork-shaped end pieces are used, then the load-bearing capacity is sufficient, but the fatigue strength is significantly reduced due to notch sensitivity at weld connections
Solution Approach 1:
The coupling element and tube are merged into a single one-piece component formed from one tube section, eliminating the weld connection between separate parts. This integration removes the notch-sensitive weld seam while maintaining the articulation function through the bolt connection in the coupling element.
Solution Approach 2:
The coupling element is formed with a localized wall thickening at the end of the tube, creating a region with enhanced local strength and stiffness where the bolt connection is located, while the rest of the tube maintains its original wall thickness and properties.
2Ease of manufacture
If traditional welded construction with separate tube sections and coupling elements is used, then manufacturing is simpler, but fatigue crack formation increases due to weld seam notches
Solution Approach 1:
The coupling element and tube are merged into a single one-piece component formed from one tube section, eliminating the weld connection between separate parts. This integration removes the notch-sensitive weld seam while maintaining the articulation function through the bolt connection in the coupling element.
3Strength
If the coupling element is formed with wall thickening, then the load-bearing capacity in the bolt connection region is improved, but the manufacturing complexity increases
Solution Approach 1:
The wall thickness parameter is changed locally at the tube end to create the coupling element. This parameter change achieves the desired load-bearing capacity enhancement without requiring additional components or complex assembly procedures.
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 solution results in a cost-effective traction rod with significantly improved fatigue strength and reduced stress concentration, minimizing the risk of early failures and associated costs.
Implementation Method 1
the wall thickening is produced by upsetting, in particular by hot upsetting of the tube end
Implementation Method 2
the wall of the tube end can also be thickened by an overlay weld
Implementation Method 3
by sintering, followed by mechanical machining
Data Source
AI summary
The invention relates to a traction rod (1) for bracing a crane jib, comprising a metallic tubular body (2) and coupling elements (3) which are connected to both ends thereof for an articulated connection of the traction rods among each other by means of bolts (5). According to the invention, the tubular body and the coupling elements consist of a one-piece tube portion, wherein the coupling elements are designed in each case as a thicker zone of the wall of the ends of the tubular body and are dimensioned in such a manner that a weakening of the cross section of the nominal wall thickness of the coupling elements, which has to be considered for calculating the load capacity of the tubular body, is prevented in the region of the bolt connection and the transition regions (7) from the respective thicker zones of the wall in the direction of the tubular body have a transition free of starting points for increasing fatigue strength.