Keyed Side Handle Assembly to Prevent Power Tool Loosening
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Solution Overview
Problem
Users of power tools with side handles often operate the tools without properly gripping the side handle, leading to instability and potential loss of control due to worn-out threads causing the side handle to become loose over time.
Innovation Solution
A side handle design with a keying feature that prevents rotation relative to the power tool, incorporating a rotatable knob for tightening without rotating the main body, and a trigger switch mechanism that ensures the side handle is properly gripped and actuated, along with an electronic switch for signal transmission to the power tool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the side handle is mounted on the power tool using a threaded rod, then the side handle can be attached to the tool, but the threads wear out over time causing the side handle to become loose and unstable
Solution Approach 1:
The side handle is divided into multiple components: a mounting member that attaches to the tool, a rod extending through the handle, and a knob for tightening. This segmentation allows the mounting member to remain fixed on the tool while only the rod and knob rotate during tightening, preventing thread wear on the mounting member and improving long-term attachment stability.
Solution Approach 2:
A keying feature (such as a keyway or spline) is introduced as an intermediary mechanism between the side handle and the power tool. This keying feature prevents relative rotation between the mounting member and the tool during operation, allowing the threaded rod to be tightened without rotating the mounting member, thereby preventing thread wear and maintaining attachment stability over time.
2Ease of manufacture
If the main gripping body is rotated to tighten the threaded rod, then the rod can be fastened to the power tool, but the trigger switch angular orientation changes and may become misaligned
Solution Approach 1:
The side handle is segmented into a mounting member for attachment and a separate gripping body for user interaction. The rod extends through both components, allowing the mounting member to be fixed to the tool while the gripping body can be independently positioned and rotated to align the trigger switch correctly, maintaining proper alignment without compromising assembly simplicity.
Solution Approach 2:
A keying feature acts as an intermediary that selectively prevents rotation. During initial assembly, the keying feature allows the mounting member to be attached to the tool. Once attached, the keying feature prevents further rotation of the mounting member relative to the tool, ensuring the trigger switch maintains its correct angular orientation while still allowing the rod to be tightened.
3Ease of operation
If the side handle threads are worn out, then the side handle becomes loose, but continuing to use it creates instability and potential loss of control
Solution Approach 1:
A keying feature (keyway or spline) is introduced as an intermediary mechanism that prevents relative rotation between the side handle and the power tool during operation. This eliminates the problem of thread wear causing looseness, as the keying feature maintains a fixed angular relationship while allowing axial movement for tightening, ensuring continuous grip stability and preventing loss of control.
Solution Approach 2:
The side handle design allows dynamic adjustment through the rotatable rod and knob mechanism, enabling the user to tighten the handle against the keying feature to eliminate play. The keying feature itself provides a dynamic solution by preventing rotation while allowing the handle to be securely tightened, maintaining operational stability throughout the tool's service life.
Data Source
AI summary
A side handle for a power tool is provided including a main gripping body; a rod extending through the main gripping body and having a threaded end extending through a frontal end of the main gripping body; and a knob mounted on an end of the rod opposite the threaded end and being rotatable relative to the main gripping body. The frontal end of the main gripping body includes a keying feature operable to engage a portion of the power tool to prevent rotation of the main gripping body relative to the power tool while the knob is rotated to fasten the threaded end of the rod to a threaded opening of the power tool.