Split Nut Adjustment Mechanism for Pruning Shear Hinge
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Solution Overview
Problem
Existing manual cutting tools, such as pruning shears, require complex systems and special tools for adjusting the hinge tightness, making it difficult for users to perform adjustments without additional devices.
Innovation Solution
A simple adjustment device using a bolt with a split nut and locking screw, where the bolt passes through both blades, and a bush improves passage, allowing for easy adjustment with a single commercially available tool, eliminating the need for special tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional retaining systems with additional pieces or elements are used, then the bolt retention is improved, but the device complexity increases and special tools are required for adjustment
Solution Approach 1:
The patent combines the retaining function and adjustment function into a single integrated nut structure. The split nut design allows the same component to both retain the bolt and enable adjustment operations with standard tools, eliminating the need for separate retaining mechanisms and special tools.
Solution Approach 2:
The nut is designed to perform multiple functions: it retains the bolt, allows adjustment of hinge tightness, and can be operated with commercially available tools. The flat faces on the nut enable it to function as both a retaining element and a tool interface, making it universally operable without specialized equipment.
2Reliability
If self-locking nuts or additional retaining elements are incorporated, then the bolt security is improved, but the ease of operation deteriorates due to requiring special tools for adjustment
Solution Approach 1:
The split nut design allows the user to perform adjustment operations directly on the retaining element itself. The same nut that secures the bolt also provides the interface for adjustment using standard tools, enabling the system to service itself without requiring separate retaining mechanisms or specialized tools.
3Device complexity
If a simple bolt and nut system is used, then the device complexity is reduced, but the bolt may rotate and become slack
Solution Approach 1:
The split nut design creates a dynamic retaining system where the nut can be easily adjusted and repositioned. The split structure allows the nut to be opened for adjustment and then closed to lock the bolt in place, providing both simplicity and reliability through its adaptable nature.
Solution Approach 2:
The flat faces on the nut act as an intermediary mechanism that prevents bolt rotation. These flat surfaces provide contact points that stop the bolt from rotating while still allowing the nut to be operated with standard tools for adjustment.
Data Source
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AI summary
The invention relates to an adjustment device for manual cutting tools. The cutting tool for which the device is intended preferably takes the form of a pruning shears having two arms (2) with the respective cutting blades (3 and 4) thereof hinged to one another by a transverse bolt (6) forming the main element of the device. The corresponding nut (7) for locking the hinge bolt (6) is provided with a transverse hole (11) into which a locking screw (10) is screwed, thereby enabling the hinge to be adjusted. The nut (7) and the locking screw (10) are positioned in a recess in the cutting blade (4) such that the nut (7) cannot rotate when the bolt (6) is being manipulated using a protrusion (14) of the nut (7) housed in a cavity (15) in the cutting blade (4). The through-hole provided in the cutting blade (3) for the bolt (6) includes a bush (13) which enables the bolt (6) to be better adjusted in the hole.