Spring-Biased Retention Flange for Secure Grinding Wheel Braking
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Solution Overview
Problem
Existing power tools face issues with grinding wheels detaching due to high inertia during rapid deceleration, particularly when a hubbed grinding wheel is used without an outer tightening nut, as the friction between the wheel and the output spindle is insufficient to prevent loosening.
Innovation Solution
A power tool design featuring a retention flange with a disc-shaped portion and a cylindrical wall, where spring members, such as Belleville discs, apply a biasing force to the retention flange, which engages with the annular rim of the output spindle to increase friction and prevent axial displacement, ensuring the wheel remains securely attached during braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a hubbed grinding wheel is used without an outer tightening nut, then the wheel can be installed and operated, but the high inertia of the wheel causes it to loosen and come off during rapid deceleration due to insufficient friction between the wheel and output spindle
Solution Approach 1:
A retention flange is introduced as an intermediary component between the grinding wheel and the output spindle. The retention flange includes a disc-shaped portion and a cylindrical wall, with spring members (such as Belleville discs) positioned between the disc-shaped portion and the output spindle. This intermediary structure provides the necessary friction and retention force to prevent the wheel from loosening during rapid deceleration, while still allowing for relatively easy installation and removal of the wheel.
2Productivity
If braking mechanisms are applied to stop the motor during fault conditions, then the motor can be braked and stopped, but the high inertia of the accessory wheel causes it to loosen and come off upon rapid deceleration
Solution Approach 1:
The spring members (Belleville discs) are pre-positioned between the retention flange and the output spindle to provide beforehand cushioning. When rapid deceleration occurs during braking, the spring members compress and expand, maintaining constant contact pressure and friction between the retention flange and the output spindle. This pre-positioned cushioning mechanism ensures the wheel remains securely retained during the sudden deceleration forces generated by braking operations.
3Reliability
If the friction between the wheel and output spindle is increased to prevent loosening, then the wheel remains secure during braking, but the structure becomes more complex with additional components
Solution Approach 1:
The retention flange serves multiple functions: it provides structural support for the grinding wheel, acts as a mounting surface for the spring members, and functions as a friction interface with the output spindle to prevent wheel loosening. The cylindrical wall of the retention flange engages with the output spindle to provide additional retention. By making the retention flange multi-functional, the design achieves reliable wheel retention without requiring numerous separate components, thus limiting the increase in structural complexity.
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 solution effectively increases the friction between the grinding wheel and the output spindle, significantly reducing the likelihood of the wheel coming off during braking, thereby enhancing the tool's operational safety and reliability.
Implementation Method 1
At least one spring member is provided engaging a first surface of the annular rim on one end and the disc-shaped portion on another end to bias the retention flange in a direction away from the annular rim
Implementation Method 2
the high inertia of the wheel upon rapid deceleration may be greater than the tightening friction between the wheel and the output spindle
Data Source
AI summary
A power tool is provided including an output spindle rotatably driven by an electric motor. The output spindle defines a longitudinal axis and includes a threaded portion near a distal end and an annular rim. A retention flange is provided including a radially-oriented disc-shaped portion having a center through-hole through which the output spindle extends and a cylindrical wall peripherally extending from the disc-shaped portion around the output spindle. The disc-shaped portion is located between the distal end and the annular rim, and the cylindrical wall extends around the annular rim. At least one spring member is disposed between the annular rim and the retention flange. A retention member is provided to restrain an axial displacement of the retention flange away from the annular rim due to the biasing force of the spring member.