Locking Nut Safety Spring Prevents Disc Detachment
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Solution Overview
Problem
Conventional hand-held power tools with disc-shaped tools face issues with inadvertent loosening of the locking nut due to inertia during sudden stops, leading to potential detachment of the disc-shaped tool from the drive spindle.
Innovation Solution
A hand-held power tool design featuring a locking nut with a safety spring radially preloaded against the locking thread, having outwardly projecting noses that engage with the disc-shaped tool's grooves, ensuring secure axial positioning even if the locking nut becomes loose due to inertia, utilizing a spring steel safety spring for high elasticity and static friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a locking nut is used to secure the disc-shaped tool on the drive spindle, then the tool can be firmly held during operation, but the locking nut may loosen due to inertia during sudden stops
Solution Approach 1:
The safety spring is preloaded against the locking thread before operation begins. This preliminary action creates a pre-compression force that acts on the locking nut, preventing it from loosening due to inertia during sudden stops. The spring is positioned and tensioned in advance to counteract the harmful inertial forces that would otherwise cause the locking nut to back off.
Solution Approach 2:
The safety spring acts as a cushioning element that absorbs and compensates for the harmful inertial forces during sudden stops. By being preloaded, the spring creates a buffer zone that prevents the locking nut from experiencing the full impact of inertial forces, thereby cushioning against the loosening effect before it can occur.
2Reliability
If additional clamping means with plate spring are added to prevent loosening, then anti-loosening reliability improves, but device complexity increases
Solution Approach 1:
The safety spring is integrated directly into the locking nut structure, merging the locking function and the anti-loosening function into a single unified component. Instead of adding separate clamping means and plate springs as distinct elements, the invention combines these functions by incorporating the spring mechanism within the locking nut itself, thereby reducing overall structural complexity while maintaining reliability.
Solution Approach 2:
The locking nut is designed to serve multiple functions: it provides the primary locking action to secure the disc-shaped tool, and simultaneously incorporates the safety spring to provide anti-loosening protection. This multi-functionality eliminates the need for separate dedicated anti-loosening components, simplifying the overall device structure while achieving the desired reliability.
3Reliability
If locking means with steel spring ring are used to brake the locking nut, then anti-loosening reliability improves, but manufacturing complexity increases
Solution Approach 1:
The invention extracts the essential braking function from the complex steel spring ring locking means and implements it through a simpler spring mechanism integrated into the locking nut. By taking out only the necessary anti-loosening function and implementing it through a more manufacturable spring element rather than a complex spring ring structure, the invention maintains reliability while improving ease of manufacture.
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 safety spring effectively prevents disc-shaped tool detachment during inertia-induced rotational conditions, providing reliable axial securing and ergonomic mounting/dismounting capabilities in multiple circumferential positions.
Implementation Method 1
safety spring formed of spring steel, which provides for a high elasticity of the safety spring
Implementation Method 2
forming at least one radial, outwardly projecting nose, with the disc-shaped tool having at least one, opening radially inwardly and axially extending groove associated with the at least one nose of the safety spring
Data Source
AI summary
A hand-held power tool has a drive spindle (2) rotatable about a rotational axis (A) and provided at its free end with a clamping flange (3) and a locking thread (4), a locking nut (7) tightenable on the locking thread (4) for securing a disc-shaped tool (5) between the clamping flange (3) of the drive spindle (2) and its clamping surface (6), and a safety spring (9) located between the disc-shaped tool (5) and an inner recess (8) formed in the clamping surface (6) of the locking nut (7), radially preloaded against the locking thread, and having at least one radial, outwardly projecting nose (10), with the disc-shaped tool (5) having at least one, opening radially inwardly and axially extending groove (11) associated with the at least one nose (10).