Impact Tool Anvil Vibration Control via Mixed Bearing Support
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Solution Overview
Problem
Impact tools, such as impact drivers, experience vibration of the bit due to clearance between the bearing and anvil during operation, leading to rattling and reduced performance.
Innovation Solution
The use of multiple bearings of differing types and configurations, including regular ball bearings, angular contact ball bearings, and self-aligning ball bearings, to axially and rotatably support the anvil, along with a contact member like an elastic O-ring to prevent bit vibration, and optimizing the insertion hole dimensions to ensure proper fit and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bearing is used to support the anvil, then the structure is simple, but clearance arises during operation causing rattling and bit vibration
Solution Approach 1:
The single bearing is divided into multiple bearings (first bearing and second bearing) that are arranged at different positions along the anvil. This segmentation allows each bearing to support specific portions of the anvil, reducing clearance and preventing rattling while maintaining reasonable structural complexity
Solution Approach 2:
The bearings are arranged not only in the radial direction but also in the axial direction along the anvil. This multi-dimensional arrangement provides comprehensive support, eliminating clearance in multiple directions and preventing bit vibration effectively
2Reliability
If multiple bearings of differing types are used to support the anvil, then rattling and bit vibration are reduced, but the device complexity increases
Solution Approach 1:
Different types of bearings (radial bearing and axial bearing) are selected for different positions along the anvil based on the specific support needs at each location. The radial bearing handles radial loads while the axial bearing handles axial loads, providing optimized local support that reduces overall complexity compared to using multiple identical bearings
Solution Approach 2:
The combination of radial and axial bearings creates a multi-functional support system that simultaneously handles both radial and axial loads on the anvil. This universal support approach prevents rattling and vibration while avoiding the need for separate bearing arrangements for each load type
Data Source
AI summary
An impact driver includes a hammer that is rotated by a motor and an anvil configured to be struck by the hammer to rotate the anvil about a rotational axis. A hammer case houses the hammer. Two or more bearings are provided inside the hammer case and support the anvil. To inhibit vibration of the anvil during operation, the bearings may be differing types, such as a regular ball bearing and an angular contact ball bearing, and/or the bearings may have different inner and/or outer diameters. A contact member, such as an O-ring, may be disposed in an insertion hole of the anvil to reduce vibrations that are transmitted to the tool bit.