Pneumatic Impact Tool Spindle Positioning Device
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Solution Overview
Problem
Conventional pneumatic impact tools experience adverse effects on smooth rotation and reduced service life due to bushing movement during power transmission, which also prevents replacement, repair, and maintenance of the spindle and output shaft.
Innovation Solution
A spindle positioning device with a bushing and a stop pin, where the bushing has a frustoconical outer surface and the stop pin is removably threaded in an inclined hole to prevent bushing movement, allowing for maintenance and replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the bushing is just threaded to the housing, then the spindle and output shaft can be removed for replacement and maintenance, but the bushing moves in the housing during power transmission, affecting smooth rotation and reducing service life
Solution Approach 1:
The positioning function is segmented into two independent components: the bushing (threaded into housing) and the stop pin (removably secured). This allows the bushing to provide continuous positioning support during operation while the stop pin can be removed for maintenance, resolving the contradiction between reliability during operation and ease of repair during maintenance.
Solution Approach 2:
The stop pin is pre-installed to secure the bushing before operation begins. This preliminary positioning action prevents bushing movement during power transmission, ensuring smooth rotation and extended service life, while the stop pin itself can be removed when maintenance is needed.
2Reliability
If glue is applied between the bushing and housing to prevent bushing movement, then the bushing is fixed in the housing, but the spindle and output shaft cannot be removed for replacement, repair, and maintenance
Solution Approach 1:
Instead of using glue (a permanent bonding method), the solution segments the fixation function into a mechanical stop pin that can be independently removed. This allows the bushing to be securely positioned during operation while enabling easy removal for maintenance, directly resolving the contradiction between reliable fixation and ease of repair.
Solution Approach 2:
The stop pin is extracted as a separate, removable component from the housing-bushing assembly. This extraction allows the bushing to be secured during operation while the stop pin can be taken out to enable maintenance, avoiding the permanent bonding issue with glue.
3Device complexity
If the bushing is threaded in the housing without additional positioning, then the structure is simple, but the bushing moves away from the output shaft during power transmission due to reaction force
Solution Approach 1:
The stop pin is positioned asymmetrically to engage with the frustoconical outer surface of the bushing at a specific location. This asymmetric positioning provides effective constraint against movement away from the output shaft while maintaining relatively simple overall structure, resolving the contradiction between simplicity and reliability.
Solution Approach 2:
The stop pin acts as an intermediary component between the housing and the bushing. It mediates the connection by providing the necessary positioning and constraint forces to prevent bushing movement, while the bushing itself remains threaded into the housing with relatively simple structure.
Data Source
AI summary
A pneumatic impact tool includes a spindle extending along an X-axis, an output shaft extending along a Z-axis, and a spindle positioning device that includes a bushing and a stop pin. The bushing is threaded in a housing, and has a stop surface and a frustoconical outer surface. The stop surface obstructs the spindle from moving away from the output shaft. The frustoconical outer surface has opposite first and second ends. The first end is nearer to the X-axis and farther away from the Z-axis than the second end. The stop pin is disposed removably in the housing, and has an engaging surface abutting against the frustoconical outer surface, so as to prevent the bushing from moving in the housing in a direction away from the output shaft.