Resilient Rail Clip Cold Setting for Hardness Variability
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Solution Overview
Problem
The variability in metal rod hardness affects the consistency of resilient rail clips' geometry due to differing elastic limits, leading to inconsistent load-deflection characteristics after cold setting, as softer rods take on more set than harder ones, making it impractical to achieve uniform clips without measuring each rod's hardness or repeatedly cold-setting them.
Innovation Solution
A method involving a two-stage cold setting process where a metal rod is loaded to or beyond the yield point of the hardest metal in the range, measuring the resulting deflection or force, and then applying additional force or deflection to achieve a predetermined permanent set, ensuring all clips have the same set and geometry, regardless of hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed deflection is applied during cold-setting, then the cold-setting process is simple to control, but clips of different hardness take on different amounts of set resulting in inconsistent geometry
Solution Approach 1:
The patent changes the control parameter from fixed deflection to force-controlled application. By applying a predetermined force that exceeds the yield point of the hardest metal in the range, the system ensures that all clips regardless of hardness within the range will yield and achieve consistent permanent set, resolving the contradiction between ease of operation and manufacturing precision
Solution Approach 2:
The patent applies a preliminary force beyond the yield point before the final shaping operation. This preliminary action ensures that the metal yields completely regardless of its specific hardness within the range, establishing a consistent baseline state before the final geometry is formed, thereby achieving uniform clip geometry
2Device complexity
If a fixed force is applied during cold-setting, then the loading process is simple, but it does not address the underlying hardness variability problem and clips still take on different amounts of set
Solution Approach 1:
The patent specifies that the predetermined force must exceed the yield point of the hardest metal in the hardness range. This parameter change ensures that even the hardest clips will yield completely, allowing all clips regardless of specific hardness to achieve consistent permanent set and geometry, thereby resolving the contradiction between device simplicity and manufacturing precision
3Manufacturing precision
If repeated cold-setting is performed, then some consistency improvement is achieved, but the process becomes time-consuming and is not fully effective
Solution Approach 1:
The patent performs the yield-inducing action in a single preliminary cold-setting operation by applying force beyond the yield point. This eliminates the need for multiple repeated cold-setting operations, achieving both consistent clip geometry and reduced processing time by resolving the hardness variability issue in one step
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 method ensures that all resilient rail clips have consistent geometry and load-deflection characteristics, overcoming the variability in metal hardness by precisely defining the geometry post-cold-setting, allowing for uniform performance across different hardness levels.
Implementation Method 1
Cold setting is intended to take the bent rod beyond that elastic limit, thereby inducing a permanent deflection (set) into the resulting clip
Implementation Method 2
Such rods have a common load-deflection characteristic with a common slope (clip stiffness) up to the elastic limit of the metal from which the bent rod is formed
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A method of manufacturing a resilient rail clip comprises bending a rod, made of metal having a hardness value falling within a known hardness value range, into a predetermined shape and then subjecting the bent rod to a cold setting process in order to induce in the bent rod a predetermined amount of permanent set (S). One cold setting process comprises applying a first load (F0) to part of the bent rod so as to cause a first amount of deflection of that part of the bent rod, which first load (F0) is a predetermined load having a value equal to or greater than that required to reach the yield point of metal having the highest hardness value in the said hardness value range, measuring the first amount of deflection (dx) of the said part of the bent rod achieved by applying the predetermined first load (F0), determining, on the basis of the measured deflection amount (dx), either (i) a second load (F0 + ?FX), which, when applied to the said part of the bent rod, will cause the bent rod to acquire the predetermined amount of permanent set (S), or (ii) a second amount of deflection (dx + ?dx) of the said part of the bent rod required in order to bring about in the bent rod the predetermined amount of permanent set (S), and applying the second load (F0 + ?FX ) to the said part of the bent rod or deflecting the said part of the bent rod by the determined second amount of deflection (dx + ?dx). An alternative cold setting process comprises deflecting part of the bent rod by a predetermined first amount (d0) by applying a first load (Fx) having a value equal to or greater than that required to reach the yield point of metal having the highest hardness value in the said hardness value range, measuring the amount of the first load (Fx) required to achieve the predetermined first amount of deflection (d0), determining, on the basis of the measured load, either (i) a second deflection amount (d0 + ?dx) required in order to bring about in the bent rod the predetermined amount of permanent set (S), or (ii) a second load (Fx + ?FX), which, when applied to the said part of the bent rod, will cause the bent rod to acquire the predetermined amount of permanent set (S), and deflecting the said part of the bent rod by the determined second deflection amount (d0 + ?dx) or applying the determined second load (Fx + ?FX) to the said part of the bent rod.