Front Bracket Welded Joint Stress Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing working machines, such as hydraulic shovels, face stress concentration issues at the welded portions of the front bracket, leading to potential structural weakness and durability problems due to repeated loading and stress application during attachment operations.
Innovation Solution
The design incorporates a front bracket with a fixed part and protruded parts that are sandwiched between vertical plates, with the protruded parts being welded to the plates along their edges, distributing the load over a wider area and enhancing the structural integrity by increasing the welded range and mitigating stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the upper part of the front bracket is welded to the upper part of the vertical plate, then the attachment can be supported and swung, but stress concentrates at the welded portion reducing durability
Solution Approach 1:
The front bracket is divided into multiple parts: an upper part with upper protruded parts, a lower part with lower protruded parts, and a middle part connecting them. This segmentation distributes the welding locations across multiple areas (upper protruded parts to upper vertical plate, lower protruded parts to lower vertical plate), preventing stress concentration at a single welded portion while maintaining the attachment swinging capability.
2Ease of manufacture
If the upper part of the vertical plate is used as a free end structure, then assembly is simplified, but strength and rigidity are reduced leading to welded portion failure
Solution Approach 1:
The vertical plate is segmented into an upper part and a lower part connected by a middle part. The upper part can be manufactured and assembled separately as a free end structure, maintaining manufacturing simplicity. The middle part connects the upper and lower parts, providing structural support and preventing the upper part from being a weak free end, thereby maintaining strength without complicating assembly.
Solution Approach 2:
The vertical plate structure is extended in the vertical dimension by adding the middle part connection. This transforms the originally single-piece vertical plate into a multi-segment structure that maintains the simplicity of separate upper part assembly while gaining enhanced strength and rigidity through the intermediate connection structure.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The invention provides a working machine that exhibits excellent strength and rigidity, by mitigating stress concentration to a welded portion of a front bracket. A front bracket 30 has a fixed part 35 that is fixed to a bottom plate 21 and vertical plates 22, and a pair of protruded parts 40 that are protruded backward from a rear part of the fixed part 35 so as to extend upper parts of sidewall parts 33. The fixed part 35 has an upper wall part 31, a lower wall part 32, a pair of sidewall parts 33 joining the upper wall part 31 and the lower wall part 32, and a rear wall part 34 joining a rear part of the upper wall part 31, a rear part of the lower wall part 32, and rear parts of the pair of sidewall parts 33. The fixed part 35 and the protruded parts 40 are sandwiched between opposite surfaces 22b that are opposite to each other at front parts of the vertical plates 22. The protruded parts 40 are welded to opposite surfaces 22b of the vertical plates 22 that are brought into contact with the protruded parts 40. Each welded portion between the protruded part 40 and the opposite surface 22b of the vertical plate 22 is formed along an edge of the protruded part 40 that is in contact with the opposite surface 22b of the vertical plate 22.