Axially Flexible Percussion Mechanism for Compact Hammer Tools
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Solution Overview
Problem
Existing percussive hand-held power tools with axially mounted percussion mechanisms face challenges in achieving a wide axial range of movement while maintaining compactness, as existing solutions like rubber guides and axial spiral compression springs limit the movable area and are not space-efficient.
Innovation Solution
The percussion mechanism is axially mounted via a transverse articulated arm and an axial sliding surface with sliding inserts made of plastic, combined with a spiral compression spring, allowing for a wide axial range of movement in a compact design, utilizing a metal-plastic pairing for low wear and incorporating a leaf spring for elasticity and economic production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a rubber guide or rubber bearing is used to mount the percussion mechanism axially movably, then the mechanism can move axially, but the movable axial area available is relatively narrow
Solution Approach 1:
The mounting system is divided into two distinct parts: a transverse articulated arm on the handle side for axial movement, and an axial sliding surface on the receiving side for guidance. This segmentation allows each component to be optimized independently, achieving wide axial range without excessive space consumption.
Solution Approach 2:
The articulated arm is oriented transversely (perpendicular to the axial direction) rather than axially, allowing the percussion mechanism to achieve axial movement through transverse articulation. This dimensional change enables wide axial range of movement while maintaining compact axial space consumption.
2Object-affected harmful factors
If the percussion mechanism is permanently mounted in the housing, then the structure is simple, but vibrations are transmitted directly to the housing
Solution Approach 1:
The transverse articulated arm and axial sliding surface act as intermediary elements between the percussion mechanism and the housing. These intermediaries allow controlled movement and reduce direct vibration transmission to the housing, while adding only moderate structural complexity.
3Reliability
If sliding inserts made of plastic with intrinsic lubricants are used, then wear is reduced, but manufacturing complexity increases
Solution Approach 1:
The sliding inserts use composite material construction - plastic matrix with intrinsic lubricants embedded within. This composite approach provides excellent wear resistance through the self-lubricating properties, while the plastic base material remains relatively easy to manufacture using conventional molding processes.
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 configuration enables a compact and space-saving design that allows the percussion mechanism to move axially over a wide range, reducing wear and maintaining a constant spring characteristic, while the rigid assembly with a gear and electric motor enhances vibration damping.
Implementation Method 1
a spring, in particular in the form of a spiral compression spring
Implementation Method 2
there is a largely constant spring characteristic over the relatively wide axial range
Implementation Method 3
sliding inserts made of plastic with intrinsic lubricants, whereby a metal-plastic pairing of materials results in a tribologically low-wear high position/low position characteristic
Implementation Method 4
tribologically low-wear high position/low position characteristic
Implementation Method 5
The articulated arm is advantageously designed as a leaf spring, further advantageously made of sheet steel, as a result of which it can be produced economically using a stamping process and is highly elastic and wear-free
Implementation Method 6
the percussion mechanism is part of an inherently rigid assembly with a gear and more advantageously with an electric motor, whereby the mass is increased in this oscillating assembly, which is beneficial for vibration damping
Data Source
Figure 1
Figure 2
AI summary
The tool has a tool fitting (2) and a hand grip (3) which is fixed at the housing (4) in which an axially movable percussion mechanism (5) is connected with the housing, axial grip-sided, by a spring (6). The percussion mechanism is mounted in the housing, fitting-sided, by an axial sliding surface (8). The axial sliding surface is mounted in the housing by a gliding insert (9), where the multiple similar gliding insert are available.