Front Loader Lifting Arm Stress Distribution
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Solution Overview
Problem
The load capacity of a front loader's lifting arm is limited by stress concentration in welded portions, particularly between the front and rear boom components and the coupling plate.
Innovation Solution
The design features a pair of lifting arms with a rear arm attached to a mast and a front arm attached to work equipment, where the front arm has a hollow, rectangular cross-section with a protruding portion that decreases in cross-sectional area, allowing the arms to be inserted and welded, distributing stress and reducing concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the lifting arm is composed of multiple parts welded together, then the ease of manufacture is improved, but the stress concentration in welded portions increases, reducing the load capacity
Solution Approach 1:
The lifting arm is divided into front and rear components that can be manufactured separately and then assembled through welding. This segmentation allows for easier manufacturing of individual parts while maintaining overall structural integrity through proper welding design.
Solution Approach 2:
The welded portions are designed with specific local characteristics - the front lifting arm has an insertion portion with a cross-sectional area that is smaller than the rear lifting arm's cross-sectional area, creating an optimized stress distribution zone. This local quality variation reduces stress concentration at the weld joints while preserving the ease of manufacturing separate components.
2Ease of manufacture
If the cross-sectional area of the welded portion is reduced to ease manufacturing, then the ease of manufacture is improved, but the stress concentration increases, reducing the load capacity
Solution Approach 1:
The insertion portion of the front lifting arm is designed with a locally reduced cross-sectional area that is smaller than the rear lifting arm's cross-section. This creates an optimized stress distribution zone that facilitates easier welding while managing stress concentration through controlled geometry rather than uniformly thick sections.
Solution Approach 2:
The design transitions from considering only the cross-sectional area to incorporating the longitudinal dimension by creating a tapered or stepped insertion portion. This dimensional variation allows stress to be distributed along the length of the weld joint, reducing peak stress concentrations while maintaining manufacturability.
Data Source
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AI summary
The present invention provides a front loader that mitigates the concentration of stress that occurs at weld parts of lifting arms. The front loader is provided with: a left/right pair of masts detachably provided to a mechanical frame of a work vehicle; a left/right pair of lifting arms coupled to the masts so as to be capable of rotating upwards and downwards; and a working tool attached to the left/right pair of lifting arms. Each lifting arm comprises: a front lifting arm mounted to the mast; and a rear lifting arm mounted to the working tool. The front lifting arm and the rear lifting arm have a rectangular shape when viewed in cross-section from the direction of extension, and are hollow. The rear end of the front lifting arm is inserted into the front end of the rear lifting arm and welded, and a side plate of the rear lifting arm has, at the insertion part, a protruding part extending along the side plate of the front lifting arm, and said protruding part is welded.