Work Machine Arm Rib Structure for Arm Joint Stress Relief
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Solution Overview
Problem
Existing work machine arms experience high stress at the joint when performing excavation at high elevation sites with the arm cylinder fully retracted due to the load received from the arm cylinder.
Innovation Solution
The work machine arm incorporates a lower plate, an upper plate, an arm cylinder bracket, and inner ribs to distribute the load received from the arm cylinder, reducing stress concentrations at the arm cylinder bracket.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the arm cylinder is retracted to the maximum extent during excavation at high elevation sites, then the excavation capability is improved, but high stress occurs at the arm joint portion
Solution Approach 1:
The arm joint portion is segmented into multiple load-bearing elements: the lower plate, upper plate, and multiple inner ribs (first inner rib and second inner rib). This segmentation distributes the concentrated load from the arm cylinder across multiple structural components, preventing stress concentration at any single point while maintaining full excavation capability.
2Device complexity
If the arm structure is simplified without inner ribs, then the device complexity is reduced, but high stress occurs at the arm cylinder bracket connection
Solution Approach 1:
Instead of uniformly complicating the entire arm structure, inner ribs are strategically placed only at critical locations where load transfer occurs between the arm cylinder bracket and the arm joint. The first inner rib connects within the connection range of the arm cylinder bracket, and the second inner rib connects to the upper plate, providing localized reinforcement exactly where needed to prevent high stress without adding unnecessary complexity elsewhere.
Data Source
AI summary
An arm cylinder bracket (7a) is connected to a lower plate (BP). An inner rib (21) is disposed inside an arm (7) and connected to the lower plate (BP) within a connection range (RA) between the lower plate (BP) and the arm cylinder bracket (7a) in a side view.