Bonded Box-Section Working Arm to Reduce Weld Stress and Fatigue
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Solution Overview
Problem
Welded plate construction in working arms for machines leads to stress and fatigue issues, requiring complex manufacturing processes and design trade-offs, and limits material selection based on weld strength rather than the strength of the steel used.
Innovation Solution
A working arm member constructed using structural panels bonded together with structural adhesives, allowing for a box section configuration that eliminates the need for welding, reduces stress and corrosion, and enables the use of different strength materials based on load requirements, with thinner higher-strength steel in high-load areas and lower-strength steel in lower-load areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If welded plate construction is used to manufacture working arms, then manufacturing simplicity and cost-effectiveness are improved, but stress and fatigue issues worsen
Solution Approach 1:
The patent replaces the welding process (mechanical joining method) with adhesive bonding. Instead of using welds to join steel plates, the invention applies adhesive layers between panels that are then cured to form strong bonds. This substitution eliminates the stress concentrations and heat-affected zones created by welding, thereby reducing fatigue issues while maintaining manufacturing simplicity.
2Strength
If welding is used to join structural panels, then structural strength is achieved, but mass increases
Solution Approach 1:
The patent changes the bonding parameters by using adhesive layers with controlled thickness (0.05-0.5mm) instead of weld metal. The adhesive bonds panels together with significantly less material than welding would require, reducing the overall mass of the working arm while maintaining equivalent or superior structural strength through distributed stress transfer across the bonded joints.
3Strength
If welding is used to construct working arms, then structural integrity is achieved, but corrosion resistance worsens
Solution Approach 1:
The patent replaces welding with adhesive bonding, which eliminates the creation of weld beads and heat-affected zones that are susceptible to corrosion. The adhesive layers provide a protective barrier between steel panels, preventing moisture and corrosive agents from penetrating to the metal surfaces, thereby significantly improving corrosion resistance while maintaining structural integrity.
4Weight of moving object
If different strength materials are used in structural panels, then weight is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by using different steel grades in different panels based on their specific load requirements. High-strength steel is used in panels experiencing greater stresses, while lower-strength steel is used in less critical areas. The adhesive bonding system facilitates this approach by allowing independent selection and assembly of panels with different material properties, actually simplifying manufacturing compared to welded construction where material transitions create welding complexity.
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 approach reduces stress and fatigue, minimizes weight, and improves aesthetics by eliminating weld beads, while also lowering manufacturing costs through reduced consumables, energy, and labor expenses.
Implementation Method 1
a first and second structural panel (52, 54) with elongate bond surfaces (55) extending between longitudinal edges thereof. A third and fourth structural panel (62, 64) extend between opposite longitudinal edges of the first and second structural panels (52, 54). The panels are bonded together using a structural adhesive
Data Source
AI summary
A structural member of a working arm of a working machine includes a first end and a second end having an elongate body extending therebetween, the body including: first and second opposing panels; third and fourth opposing panels, the third panel extending between a first edge of the first and second panels and the fourth panel extending between a second edge of the first and second panels to provide a box section; the third and fourth panels comprising: at least one pivot mount for connecting the working arm member to a further working arm member or the working machine; and, at least one actuator mount for connecting a working actuator, the working actuator being operable to move the working arm member, wherein the first, second, third and fourth panels are structurally bonded together by an adhesive.