Compact Damper With Anisotropic Stiffness For Power Tool Vibration
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Solution Overview
Problem
Hand-held power tools experience significant vibrations due to their high inertia, leading to user discomfort and potential injury from kickbacks, which existing dampers fail to adequately address, especially in compact designs where space is limited.
Innovation Solution
A compact damper design featuring a spring body made of elastomer and a mass body connected indirectly through a carrier plate, with the spring body being stiffer in the assembly direction and having varying stiffness in three spatial directions to effectively absorb vibrations while minimizing tilting and rotating movements, utilizing a combination of plastic and closed-pore foamed polyurethane materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional damper design is used, then vibration damping is provided, but the damper occupies excessive space and lacks compactness
Solution Approach 1:
The mass body is positioned inside the spring body, with the mass body's outer surface fitting within the inner surface of the spring body. This nested configuration allows the heavy mass required for effective vibration damping to be contained within the compact spring body structure, achieving both compactness and damping effectiveness.
Solution Approach 2:
The spring body is designed with different stiffness characteristics in different spatial directions - stiffer in the assembly direction (vertical) and more compliant in horizontal directions. This anisotropic stiffness design allows the damper to maintain a compact vertical profile while providing effective vibration damping in the horizontal vibration directions.
2Reliability
If the spring body is made uniformly stiff in all directions, then structural stability is improved, but the ability to dampen vibrations in all directions is reduced
Solution Approach 1:
The spring body exhibits different mechanical properties in different directions - it is stiffer in the assembly direction and more compliant in horizontal directions. This directional variation in stiffness allows the same structural element to provide both stability in the assembly direction and effective vibration damping in horizontal directions, without requiring additional complex components.
3Strength
If the mass body is directly connected to the spring body, then connection strength is improved, but tilting and rotating movements are not suppressed
Solution Approach 1:
The carrier plate serves as an intermediary component between the mass body and the spring body. It provides a stable connection interface that maintains parallel orientation of the mass body relative to the spring body, preventing tilting and rotating movements while ensuring strong mechanical connection through material connection.
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 solution effectively dampens vibrations, reducing user discomfort and preventing unwanted tilting and rotating movements, while maintaining a compact and efficient design that resonates with the periodic excitation of the linear drive, thus enhancing the usability and safety of hand-held power tools.
Implementation Method 1
a spring body (21) made of an elastomer (1.1), which is materially connected to the base plate (2) and/or to the carrier plate (1)
Implementation Method 2
Due to its high inertia, the mass body (22) can be excited to move relative to the housing (17) of the power tool
Implementation Method 3
Due to the movement of the mass body, the spring body undergoes shearing, which shifts the roof surface parallel to the base surface
Data Source
Figure 1
Figure 2~4
Figure 5~7
AI summary
A hand-held power tool (1) has a housing, a linear drive for moving a tool along a working axis (9) and a shock absorber (20). The shock absorber (20) is made up of layers in a building-up direction (23) perpendicular to the working axis (9), comprising a base sheet (24), formed from plastic, a spring body (21), comprising an elastomer, a supporting sheet (25), formed from plastic, a spring body (21), comprising an elastomer, and a mass body (22), fastened on the supporting sheet (25). The spring body (21) is joined with a material bond to the base sheet (24) and/or to the supporting sheet (25).