Telescoping Boom Primary Secondary Shell Assembly
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Solution Overview
Problem
Conventional mobile cranes face a challenge in achieving a balance between increased boom strength and reduced weight, as adding thickness to the base section for strength complicates manufacturing and increases weight, violating weight restrictions for over-the-road travel and lifting power constraints.
Innovation Solution
A telescoping boom assembly with a primary shell and a secondary shell connected externally, forming a gap between the inner and outer surfaces, which provides targeted strengthening without significantly increasing weight, using a U-shaped secondary shell that tapers and ribs for enhanced structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the shell forming the base section is increased to increase boom strength, then the strength is improved, but the weight increases and manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by adding a secondary shell only to the base section of the boom where strength is most needed, rather than uniformly increasing the thickness of the entire boom. This allows the boom to have increased strength at critical locations while maintaining lighter weight in non-critical sections, thus resolving the contradiction between overall strength and total weight.
Solution Approach 2:
The boom base section is segmented into a primary shell and a secondary shell that are attached together. This segmentation allows the structure to achieve the strength of a thicker single shell while using thinner individual components, which can be manufactured more easily and with less weight than a solid thick shell would require.
2Strength
If the thickness of the shell forming the base section is increased to increase boom strength, then the strength is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The boom base section is segmented into a primary shell and a secondary shell that are attached together. This segmentation allows the structure to achieve the strength of a thicker single shell while using thinner individual components, which can be manufactured more easily and with less weight than a solid thick shell would require.
Solution Approach 2:
The patent merges the primary shell and secondary shell into a composite structure that provides the strength of a thick shell while using thinner, easier-to-manufacture components. The attachment of these shells creates a unified structure that achieves the desired strength without the manufacturing difficulties of forming a single thick curved shell.
3Strength
If a doubler is welded directly to the rounded underside of the primary shell to increase thickness, then the strength is improved, but deformation occurs in the underlying material
Solution Approach 1:
The patent introduces an intermediary approach by using a secondary shell that attaches to the external surface of the primary shell rather than welding directly to the rounded underside. This intermediary configuration distributes the strengthening effect without concentrating stress at weld points, thereby preventing the deformation that would occur with direct welding of a doubler to the curved surface.
Data Source
AI summary
A mobile crane includes a boom extension assembly having a base boom section with a primary shell and a secondary formed shell attached thereto, which allows for selective strengthening along the length of the base boom section. Methods involve manufacturing a boom assembly including such a base boom section.