Handle Fastening Mechanism for Power Tools
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Solution Overview
Problem
Existing hand-held power tools face challenges with auxiliary handles that are difficult to securely and quickly attach due to large interfering contours and time-consuming screwing processes, particularly in angle grinders.
Innovation Solution
The design incorporates an adjustable element within the fastening means that allows for a positive or non-positive connection between the handle and the power tool, featuring a recess without an internal thread and an extension that can be partially inserted in a form-fitting manner, enabling quick and secure attachment with minimal interfering contour.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional threaded fasteners are used to secure the handle, then a sufficiently strong connection is achieved, but the axial length of the fastening becomes large and the screwing process takes a long time
Solution Approach 1:
The patent replaces the traditional threaded mechanical fastening system with a bayonet coupling mechanism. The handle extension features a protrusion that inserts into a recess in the power tool, and a rotary locking element engages with the recess to secure the connection through rotational movement rather than threading, dramatically reducing assembly time while maintaining connection strength.
Solution Approach 2:
Instead of screwing the handle into the power tool (rotational movement to create threaded engagement), the invention inverts the sequence: first insert the handle axially into the power tool, then rotate the locking element to secure it. This reversal of the fastening sequence eliminates the time-consuming threading process.
2Strength
If traditional threaded fasteners are used to secure the handle, then a sufficiently strong connection is achieved, but the interference contour becomes large
Solution Approach 1:
The bayonet coupling mechanism replaces the bulky threaded fastener system with a compact insert-and-lock structure. The protrusion on the handle extension fits into a recess in the power tool housing, and the rotary locking element secures the connection with minimal radial and axial dimensions, significantly reducing the interference contour.
3Productivity
If a quick-release mechanism is used to reduce assembly time, then attachment speed is improved, but the connection strength and security may be compromised
Solution Approach 1:
The bayonet coupling mechanism incorporates a dynamic locking element that rotates to engage with the recess, creating a secure positive lock. The locking element can be quickly rotated to attach or detach the handle, providing both rapid attachment speed and strong, secure connection through the mechanical interlocking of the protrusion and recess.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
The tool has fastening units (10) for releaseably fastening a handle e.g. additional handle, to the tool, where the fastening units comprise an extension (5) e.g. pin, that is accommodated in a recess in segments. The extension is arranged on the handle or tool and the recess is arranged in the tool or handle. The fastening units comprise a spring element (6) such as U-shaped round wire spring, that is adjustable relative to the extension and engaged during establishing and/or releasing and/or securing a form-fit and/or friction-fit connection between the handle and the tool.