Impact Tool Hammer Claw Geometry for Stress Reduction
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Solution Overview
Problem
The increasing output of impact tools poses a risk of mechanical component damage, particularly in the striking mechanism, due to stress concentration at the outer diameter side end of the hammer claw, leading to potential damage and requiring countermeasures to reduce stress and improve workability.
Innovation Solution
The impact tool design includes a hammer with a main body part and a claw part, where the front inner diameter side end of the main body part is located in front of the front outer diameter side end, and the claw part protrudes from a tapered surface toward the anvil, ensuring a relationship of L1 < L2, and featuring a groove with a predetermined radius of curvature at the connection corners of the hammer parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the number of sets of hammer claws and anvil blades is increased to three to distribute contact force, then the force applied to each contact place is reduced, but an extremely large stress occurs in the vicinity of the outer diameter side end of the root of the hammer claw when not all places undergo collision simultaneously
Solution Approach 1:
The invention applies different geometric characteristics to different parts of the hammer claw. Specifically, the inner diameter side end of the claw part has a different length (L1) than the outer diameter side end (L2), creating local geometric variation. This allows the stress distribution to be optimized locally at critical areas without changing the overall three-set configuration, thereby reducing extreme stress concentration at the root while maintaining force distribution benefits.
Solution Approach 2:
The hammer claw is designed with asymmetric geometry where the inner diameter side end and outer diameter side end have different lengths from the main body part. This asymmetric design (L1 ≠ L2) creates different leverage arms and stress distribution patterns, preventing extreme stress concentration at any single location while maintaining the three-set configuration for force distribution.
2Stress or pressure
If grooves with large radius of curvature or chamfering are provided at the root of the hammer claw to reduce stress, then stress concentration is reduced, but the overall length of the product increases or the number of processing steps increases
Solution Approach 1:
The invention changes the geometric parameters of the hammer claw by making the inner diameter side end length (L1) different from the outer diameter side end length (L2). This parameter change creates inherent stress distribution optimization through geometric design alone, eliminating the need for additional grooves or chamfers, and thus avoiding increased processing steps or product length.
3Power
If the output of the impact tool is increased by strengthening the power source and motor, then the motor performance is improved, but the mechanical components such as the striking mechanism may be unable to withstand the output and may be damaged
Solution Approach 1:
By creating local geometric variations in the hammer claw (different lengths L1 and L2 at inner and outer diameter sides), the invention optimizes stress distribution at critical locations. This allows the striking mechanism to handle higher motor output without damage, improving reliability while maintaining high power capability.
Solution Approach 2:
The asymmetric design of the hammer claw with unequal lengths L1 and L2 creates optimal stress distribution patterns that enable the striking mechanism to withstand higher forces from improved motor output, thereby improving reliability without sacrificing power.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces stress concentration at the joint between the hammer's main body and the claw, allowing for a more compact striking mechanism while maintaining reliability and durability.
Implementation Method 1
a hammer (30), relatively movable in an axial direction and a rotation direction within a predetermined range with respect to the spindle (26) and energized forward by a cam mechanism and a spring
Data Source
AI summary
An impact tool includes a hammer that is rotated by a motor and energized toward a front side from a spindle by a cam mechanism and a spring, and an anvil that is struck by the hammer. The hammer includes a main body part, and claw parts extending forward from the main body part, and tapered surfaces are formed such that an inner diameter side end of each of the claw parts of the main body part is located on the front side relative to an outer diameter side end of the claw part. The tapered surfaces are formed, on an outer peripheral side of a front facing surface of the hammer, in such a shape that the tapered surfaces recede as separating in a radial direction from a rotation axis.