Saw Chain Preset Rivets: Non-Concentric Geometry and Selective Hardening
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Solution Overview
Problem
The configuration and assembly of saw chain presets, particularly involving rivets and tiestraps, lead to wear-related issues that increase the likelihood of chain shot events, affecting the longevity and safety of saw chains.
Innovation Solution
The use of oriented non-concentric rivets with selective hardening and brazing techniques to optimize the geometry and material properties of saw chain presets, enhancing wear resistance and durability while maintaining ductility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional rivet and tiestrap assembly is used, then manufacturing simplicity is maintained, but wear resistance and durability deteriorate
Solution Approach 1:
The patent applies selective heat treatment to specific regions of the rivet and tiestrap components. The rivet flange contact surfaces and tiestrap bearing surfaces are hardened to high hardness levels (HRC 58-65) to maximize wear resistance at critical wear zones, while other portions of the components maintain lower hardness for ductility and manufacturability. This localized property differentiation resolves the contradiction by providing enhanced wear resistance only where needed.
Solution Approach 2:
The patent employs non-concentric rivet hole positioning in the tiestrap, where the rivet holes are offset from the central axis. This asymmetric configuration optimizes the load distribution and wear patterns on the rivet-flange and tiestrap interfaces, improving durability under operational stresses while maintaining manufacturing feasibility through standardized offset dimensions.
2Duration of action of stationary object
If rivet and tiestrap wear increases, then longevity is reduced, but chain shot risk increases
Solution Approach 1:
The patent implements preventive hardening of the rivet and tiestrap components before assembly and use. By pre-hardening the critical contact surfaces through selective heat treatment, the components are prepared in advance to resist wear that would otherwise lead to chain failure and potential chain shot events. This proactive approach extends chain longevity while maintaining safety by preventing wear-related failures before they occur.
3Strength
If selective heat treatment is applied, then wear resistance improves, but manufacturing process complexity increases
Solution Approach 1:
The selective heat treatment process targets only specific regions of the components - primarily the rivet flange contact surfaces and tiestrap bearing surfaces. This localized treatment approach achieves the necessary hardness (HRC 58-65) at critical wear zones without requiring entire-component hardening, thereby reducing the complexity and cost of the heat treatment process while maintaining improved wear resistance where it matters most.
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 results in longer-lasting saw chains with improved tolerance for wear and tear, better performance, and reduced risk of chain shot events by optimizing the material properties and geometry of presets.
Implementation Method 1
brazing techniques to optimize the geometry and material properties of saw chain presets
Implementation Method 2
post-assembly selective heat treatment
Data Source
AI summary
Embodiments herein describe presets for saw chains comprised of one or more rivets that are coupled to a tiestrap. Each rivet may further comprise a central flange and a hub protruding from opposed sides from the flange. In some embodiments, the hub may be non-concentric from the flange, and the flange may be non-circular, such as ovoid or cam-shaped. In some embodiments, various portions of the flange, rivet, and tiestrap may be selectively hardened to various degrees of hardness, depending upon their location and usage. In some embodiments, the rivets may be prevented from rotating with respect to the tiestrap using a brazing process, and may be configured to facilitate such processes. Other embodiments may employ a non-circular hub. Still other embodiments may use a low-temperature process for soldering that does not affect the hardness of the tiestrap or rivet.