Branch Shears with Coaxial Traction Roller for Consistent Force
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Solution Overview
Problem
Existing branch cutting scissors lack optimal handling and force transmission efficiency, particularly when cutting branches of varying thickness, leading to uncomfortable operation and potential force imbalances.
Innovation Solution
The scissors incorporate a traction mechanism with a rotating traction roller having a non-round contour wrapping surface, aligned coaxially with the joint axis, allowing for variable force transmission and adaptation to cutting force curves, combined with a gear device for enhanced force transmission and a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the traction means is arranged coaxially to the joint axis, then the cutting area can be angled relative to the handle device without lengthening or shortening the traction means, but the force transmission efficiency may be compromised
Solution Approach 1:
The traction roller is designed with a non-circular contour in the wrap-around surface, creating variable effective radii that optimize force transmission at different angular positions while maintaining coaxial alignment with the joint axis
Solution Approach 2:
The non-circular contour allows the effective radius to vary dynamically during rotation, adapting the mechanical advantage to match the cutting force requirements at different angles of the cutting area relative to the handle device
2Ease of operation
If a non-circular contour is used on the traction roller, then variable force transmission is achieved to match cutting force curves, but the manufacturing complexity increases
Solution Approach 1:
The non-circular contour modifies the geometric parameters of the traction roller to create variable effective radii, enabling force transmission optimization without fundamentally changing the roller's basic structure or manufacturing process
3Device complexity
If the joint device is housed in the blade housing, then the structure becomes more compact and cost-effective, but the space for force transmission components is reduced
Solution Approach 1:
The joint device is nested within the blade housing structure, with the traction roller and other components arranged in a compact configuration that maximizes space utilization while maintaining force transmission capability
Solution Approach 2:
The joint axis is aligned essentially parallel to the cutting plane, utilizing spatial arrangement in multiple dimensions to achieve effective force transmission within the constrained housing space
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
This design ensures a comfortable and efficient cutting experience by maintaining a consistent actuation force across varying cutting tasks, reducing force jumps, and allowing for effective angle adjustment without lengthening or shortening the traction means, thus providing improved handling and cost-effective manufacturing.
Implementation Method 1
the support area wrapped by the traction mechanism has a non-circular contour in a wrap-around surface determined by the traction mechanism, thereby with at least two differing effective radii
Implementation Method 2
a gear mechanism is provided between the traction mechanism pulley and the scissor part
Implementation Method 3
the cable is attached directly to the shearing part and is guided there via two guide rollers
Data Source
Figure 1
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AI summary
To improve the handling of a pair of shears (1) for cutting branches, with at least two correspondingly designed shear blades (2) that can be moved relative to each other by means of a pull rod (7), an arrangement is proposed which always provides the same cutting area between the shear blades, regardless of the pivoting of the cutting area relative to the handle (10). The shears are equipped with a pivoting mechanism (11) for pivoting. In particular, the pull rod (7) is arranged coaxially with a pivot axis (20) of the pivoting mechanism, so that pivoting the cutting area does not shorten or lengthen the pull rod. Furthermore, by housing the pivoting mechanism (11) in a blade housing (9) that at least partially surrounds the blades, a particularly cost-effective design of the shears is made possible.