Integrally Cast Excavator Bucket Hinge for Fatigue-Resistant Load Transfer
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Solution Overview
Problem
Excavator buckets face failures due to fatigue stress at welded joints, leading to reduced productivity and increased maintenance costs, as they are subjected to extreme loads and wear during operations.
Innovation Solution
The development of an excavator bucket with an integrally cast hinge assembly, manufactured through a casting process using alloy steel, which eliminates welds and features a torque tube structure with radiused intersections to distribute load gradually, enhancing structural strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If buckets are made from welded-together pieces, then manufacturing flexibility and ease of assembly are improved, but the welded joints become areas where cracks and failures due to fatigue stress can occur
Solution Approach 1:
The patent merges multiple separate components (bucket body, hinge assembly, torque tubes) into a single integrally cast structure. This eliminates the welded joints between these components, removing the primary locations where fatigue cracks would initiate. The hinge assembly is cast as one piece with the bucket, creating a unified structure that maintains manufacturing feasibility while dramatically improving fatigue resistance.
2Reliability
If an integrally cast hinge assembly is used, then fatigue resistance and structural strength are improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the casting process into manageable stages: forming the bucket body, then the hinge assembly, and finally integrating them. This segmented approach to an otherwise complex integral structure allows for controlled manufacturing of each section while achieving the overall benefit of an weldless, fatigue-resistant structure.
Solution Approach 2:
The patent incorporates radiused intersections and curved transitions in the hinge assembly design, replacing sharp corners with smooth radii. This not only improves stress distribution and fatigue resistance but also facilitates the casting process by allowing molten metal to flow more easily into complex geometries, thereby reducing manufacturing complexity.
3Ease of repair
If welded joints are used in the hinge assembly, then ease of repair and component replacement are improved, but the welded joints are prone to cracks and failures
Solution Approach 1:
By merging the hinge assembly with the bucket body into an integral cast structure, the patent eliminates weak welded joints while maintaining overall structural integrity. The unified structure ensures that load paths are continuous and free from discontinuities at joints, significantly improving joint strength and fatigue resistance.
4Adaptability or versatility
If multiple separate components are welded together, then adaptability and customization options are improved, but the number of welded joints increases leading to more failure points
Solution Approach 1:
The patent maintains design flexibility through segmentation of the casting process and modular design considerations, allowing different bucket configurations while minimizing the need for welded joints. Each segment can be customized during the casting process without requiring post-casting assembly through welding.
Data Source
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AI summary
An integrally cast hinge assembly (40) for a bucket (10), including a first hinge plate, a second hinge plate spaced apart from the first hinge plate, and a torque tube portion extending between the first hinge plate and the second hinge plate, wherein the first hinge plate is weldlessly connected to the torque tube portion and the second hinge plate is weldlessly connected to the torque tube portion. A method of manufacturing a machine bucket (10), comprises the steps of: welding a first side plate (18) to a first side edge of a wrapper (24); welding a second side plate (20) to a second side edge of the wrapper (24); welding a support plate (22) to an upper edge (24) of the wrapper (24) and to each of the first side plate (18) and the second side plate (20); welding a first torque tube portion (34) to the support plate (22) and the first side plate (18); welding a second torque tube portion (36) to the support plate (22) and the second side plate (20) such that a gap (38) is formed between the first and second torque tube portions (34, 36); providing a cast hinge assembly (40) including a first hinge plate (42), a second hinge plate (46), and a third torque tube portion (49) as an integral, weldless structure; and positioning the cast hinge assembly (40) within the gap (38) and welding the cast hinge assembly (40) to the support plate (22), the first torque tube portion (34), and the second torque tube portion (36).