Self-Lubricating Powdered Metal Bushing for Impact Tool Stability
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Solution Overview
Problem
Existing impact tools face issues with wear and stability due to high friction and wobble in their drive assemblies, particularly in the support of anvil components, which affects the tool's performance and longevity.
Innovation Solution
A power tool design incorporating a powdered metal bushing within the front casing that is lubricant-impregnated, providing self-lubricating properties to reduce wear and wobble, and a drive assembly with a hammer mechanism that imparts consecutive rotational impacts on the anvil, supported by a powdered metal bushing for improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bushing is used to support the anvil, then the structure is simple, but high friction and wobble occur leading to wear and reduced stability
Solution Approach 1:
The bushing is made from porous powdered metal material that allows lubricant impregnation. The porous structure enables the bushing to absorb and retain lubricant within its matrix, providing continuous lubrication to reduce friction and prevent wobble during impact operations, thereby improving reliability without significantly increasing structural complexity
Solution Approach 2:
The bushing combines powdered metal base material with impregnated lubricant to create a composite structure. This composite approach integrates the structural support function of the metal bushing with the low-friction properties of the lubricant, simultaneously addressing wear and stability issues while maintaining manufacturing simplicity
2Duration of action of moving object
If high friction is present in the drive assembly, then manufacturing is simple, but wear increases and performance deteriorates
Solution Approach 1:
The lubricant is impregnated into the powdered metal bushing during the manufacturing process itself, before the bushing is installed in the tool. This preliminary action ensures that the bushing starts with built-in lubrication, reducing friction from the first use and extending the duration of action without requiring complex post-manufacturing assembly steps
Solution Approach 2:
The manufacturing process parameters are modified to include lubricant impregnation during sintering or after sintering. By changing the manufacturing parameters to incorporate this additional step, the bushing gains self-lubricating properties that reduce wear and extend longevity, while the overall manufacturing complexity remains manageable
3Reliability
If anvil wobble is not controlled, then the device structure is simple, but performance and lifespan are reduced
Solution Approach 1:
The porous powdered metal bushing provides a compliant yet stable support for the anvil. The porous structure allows for lubricant retention that reduces friction-induced wobble, providing stable anvil support during impact operations. This approach improves performance by controlling wobble without requiring complex rigid support structures
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
The lubricant-impregnated powdered metal bushing reduces friction and wobble, enhancing the stability and longevity of the impact tool by maintaining low-friction operation and preventing anvil wobble, thereby improving the tool's performance and lifespan.
Implementation Method 1
a lubricant-impregnated bushing disposed within the front casing that rotatably supports the anvil
Implementation Method 2
immersing the gear case in lubricant so that the lubricant is wicked into the bushing to impregnate the bushing with the lubricant
Implementation Method 3
the lubricant is wicked into the bushing to impregnate the bushing with the lubricant
Implementation Method 4
the lubricant is wicked into the bushing to impregnate the bushing with the lubricant
Implementation Method 5
reduces friction and wobble, enhancing the stability and longevity of the impact tool
Data Source
AI summary
A tool includes a housing, a drive assembly including an output shaft extending from the housing such that a tool element for performing work on a workpiece is attachable to the output shaft, and a bushing disposed within the housing. The bushing rotatably supports the output shaft. The bushing is impregnated with lubricant such that the bushing is self-lubricating, and the bushing has an impregnation ratio between about 5% and about 25%.