Impact Tool Anvil Guide Structure for Lower Stress Concentration
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Solution Overview
Problem
Existing impact tools suffer from anvil fatigue failure due to high stress levels, leading to potential breakage and reduced durability, primarily because the anvil design concentrates stress at the boundary between the adjoining and stem parts.
Innovation Solution
The anvil design incorporates a guide part extending axially beyond the lugs, allowing the main shaft to extend deeper into the anvil without increasing its length, featuring a tubular guide part with a continuous peripheral wall and reinforcing ribs for enhanced strength and stability, thereby reducing stress concentration and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main shaft extends deeper into the anvil to improve guiding function and reduce wear, then the guiding performance and durability are improved, but the anvil length increases and stress concentration occurs at the boundary between adjoining part and stem part
Solution Approach 1:
The guide part is designed as a tubular structure that extends axially beyond the bottom face of the lug, allowing the main shaft to extend deeper into the anvil through this nested configuration. This enables improved guiding function and wear reduction without proportionally increasing the overall anvil length, as the guide part utilizes the existing structural space efficiently.
Solution Approach 2:
The guide part extends in the axial dimension beyond the bottom face of the lug, creating an additional guiding zone without increasing the radial or transverse dimensions. This dimensional extension allows the main shaft to have better guidance and support while maintaining a compact overall anvil size.
2Reliability
If the hole of the tubular stem part is made deeper to accommodate longer main shaft extension, then the guiding function is improved, but the strength of the anvil is reduced and stress concentration occurs at the boundary between adjoining part and stem part
Solution Approach 1:
The guide part is designed as a tubular structure that extends axially beyond the bottom face of the lug, allowing the main shaft to extend deeper into the anvil through this nested configuration. This enables improved guiding function and wear reduction without proportionally increasing the overall anvil length, as the guide part utilizes the existing structural space efficiently.
Solution Approach 2:
The anvil is segmented into distinct functional parts: the head, the stem part, the guide part extending beyond the lug bottom face, and the lugs themselves. This segmentation allows each part to be optimized for its specific function - the guide part provides guiding without requiring the entire anvil to be longer, and the lugs provide structural support at critical locations.
3Length of stationary object
If the anvil is made more compact to reduce overall tool size, then the tool portability is improved, but the power and torque transmission capability is reduced
Solution Approach 1:
The anvil employs local quality enhancement through the guide part that extends axially beyond the bottom face of the lug. This localized structural feature provides improved guiding and torque transmission capability at the critical main shaft interface without requiring a proportional increase in overall anvil dimensions. The guide part's tubular configuration with specific wall thickness optimizes local strength-to-weight ratio.
Solution Approach 2:
The anvil utilizes composite structural design combining the head, stem part, guide part, and lugs into an integrated component. This composite structure optimizes material distribution to achieve high torque transmission capability in a compact form, with each segment contributing specific mechanical properties to the overall assembly.
Data Source
AI summary
An impact tool, including a casing, a drive disposed in the casing, a main shaft and a gear assembly connected to the drive, a hammer assembly connected to the gear assembly and main shaft, and an anvil, the main shaft defining a rotation axis around which the hammer assembly and anvil can rotate, the anvil having a head and a stem part, the stem part being substantially cylindrical, and at least one lug extending radially from that end of the stem part which is remote from the head, forming a bottom face substantially perpendicular to the rotation axis R; the anvil further includes a guide part extending axially from that end of the stem part which is remote from the head, and a front end of the main shaft is accommodated in the guide part.