Hammer Handle Asymmetric Cross-Section Stiffness
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Solution Overview
Problem
Conventional hammer handles flex or bend when used to remove large or deeply embedded nails, particularly when the side pulling method is employed, leading to mechanical stress and reduced lateral stiffness due to their thin design.
Innovation Solution
A hammer design featuring a handle with a concavo-convex shaped cross-sectional configuration, including a longitudinal projection on one side and a recess on the opposite side, which increases lateral stiffness while maintaining a lightweight configuration by optimizing the ratio of maximum handle thickness to overall width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the steel shaft width is increased to increase lateral stiffness, then the lateral stiffness is improved, but the overall weight of the hammer increases
Solution Approach 1:
The patent applies asymmetry by providing a longitudinal projection on one side of the handle and a longitudinal recess on the opposite side, creating an asymmetric cross-sectional shape that optimizes lateral stiffness without requiring a uniform increase in width throughout, thereby managing weight more effectively
Solution Approach 2:
The patent applies local quality by concentrating material in specific locations (longitudinal projection on one side, recess on the other) rather than uniformly thickening the entire handle, providing enhanced lateral stiffness where needed while maintaining lighter weight in other areas
2Strength
If the handle is designed for strength in the swing plane, then the strength in swing plane is improved, but the handle flexes or bends when force is applied perpendicular to the swing plane
Solution Approach 1:
The asymmetric cross-sectional design with a longitudinal projection on one side and recess on the other provides different moment of inertia values about different axes, optimizing resistance to bending in both the swing plane and perpendicular directions while maintaining strength characteristics
Data Source
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AI summary
A hammer that includes a handle and a head is provided. The handle has a bottom end, an upper portion, and a longitudinal axis extending in a swing plane of the hammer. The head is disposed on the upper portion of the handle. The head has a strike face, and the strike face has a longitudinal axis extending in the swing plane of the hammer. A majority of the longitudinal length of the handle has a longitudinal projection on a first side of the handle and a longitudinal recess on a second side of the handle opposite the first side. The first side of the handle and the second side of the handle generally face opposite directions that are perpendicular to the swing plane.