Stud Bolt Force Transmission for Low-Wear Tool Attachment

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Solution Overview

Problem

Existing tools, such as chainsaws, experience wear and destabilization of the connection between the guide bar and the housing due to the rapid degradation of silicone sleeves used for damping forces, leading to potential detachment and instability.

Innovation Solution

The use of transmission elements made from materials with a modulus of elasticity between 1 GPa to 80 GPa, or incorporating a spring element with a modulus greater than 80 GPa and a free space for spring travel, to effectively dampen and transmit forces without significant wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a silicone sleeve is used to dampen forces between the guide bar and stud bolt, then the connection is protected from force transmission, but the silicone sleeve wears out quickly and loses its damping effect

Engineering Contradiction:
Improveconnection stabilityVSAvoidservice life of damping element
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent changes the material parameter (modulus of elasticity) from silicone (~0.01-0.1 GPa) to materials with higher elasticity (1-80 GPa), fundamentally altering the wear characteristics while maintaining the damping function. This parameter change transforms the damping element from a soft, wear-prone material to a more durable material that resists wear while still providing force dampening.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures, particularly in the second element where a spring element (high elasticity material) is combined with a damping element. This composite approach allows the spring element to provide structural integrity and wear resistance while the damping element maintains the force absorption capability, solving both the reliability and durability requirements simultaneously.

Inventive Principle:
Principle #40Composite materials

2Duration of action of moving object

If a harder material is used for the transmission element to reduce wear, then the service life increases, but the damping effect decreases

Engineering Contradiction:
Improveservice life of transmission elementVSAvoidforce dampening capability
Core Design Contradiction:
Duration of action of moving objectVSReliability

Solution Approach 1:

The transmission element is segmented into distinct functional components: a spring element for structural support and wear resistance, and a damping element for force absorption. This segmentation allows each component to be optimized for its specific function - the spring element provides durability while the damping element maintains the dampening effect, resolving the contradiction between wear resistance and damping capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses composite material construction where a spring element made of high-elasticity material (1-80 GPa) is combined with a damping element. The spring element provides the necessary wear resistance and structural integrity, while the damping element maintains the force absorption capability. This composite approach allows both hard (wear-resistant) and soft (damping) properties to coexist in the same transmission element.

Inventive Principle:
Principle #40Composite materials

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 solution ensures safe and low-wear operation by minimizing damage to the connection between the stud bolt and the housing, allowing for efficient force transmission even at high frequencies.

Implementation Method 1

the first element consists at least partially of a first material which has a modulus of elasticity of 1 GPa to 80 GPa... the first element wears only to a very small extent and at the same time sufficiently dampens the transverse forces transmitted from the tool to the stud bolt

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the second element has a spring element made at least partially from a second material with a modulus of elasticity greater than 80 GPa and a free space for the spring element to travel

Methodology Applied
Scientific EffectSpring deflection: Spring

Data Source

PatentEP3932635B1Work device
Publication Date: 2025.07.30 ANDREAS STIHL AG & CO KG
  • EP3932635B1 patent drawingFigure 1~2
  • EP3932635B1 patent drawingFigure 3~4
  • EP3932635B1 patent drawingFigure 5~6

AI summary

The invention relates to a working device comprising a tool (4), a housing part (2), and a stud bolt (3) screwed into the housing part (2) for attaching the tool (4) to the housing part (2). The stud bolt (3) projects from the housing part (2) along an axial direction (50). The tool (4) has an opening (5) into which the stud bolt (3) projects at least partially. The working device (1) has a transmission element for transmitting transverse forces acting perpendicular to the axial direction (50) from the tool (4) to the stud bolt (3).The transmission element is designed as a first element (10) and consists at least partially of a first material having a modulus of elasticity of 1 GPa to 80 GPa, or the transmission element is designed as a second element (20) and has a spring element (21) at least partially made of a second material with a modulus of elasticity greater than 80 GPa and a clearance (22) for a spring travel of the spring element (21).