Urethane Bumper Spring Density and Cell Diameter Control
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Solution Overview
Problem
Urethane bumper springs using foamed polyurethane resin face challenges in achieving cost reduction while maintaining durability and settling resistance under high load and high deformation, primarily due to the high material cost of 1,5-naphthalene diisocyanate and issues with durability and strain-induced cracks when using diphenylmethane diisocyanate.
Innovation Solution
A urethane bumper spring with a hollow cylindrical shape, produced through mold forming, utilizing a polyester-based polyol and diphenylmethane diisocyanate as an isocyanate component, with specific density and foamed cell diameter relationships between the skin layer and core portion to enhance durability and cost-effectiveness, involving a two-stage heating process for primary and secondary vulcanization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 1,5-naphthalene diisocyanate (NDI) is used as isocyanate component, then durability and settling resistance are improved, but material cost increases
Solution Approach 1:
The invention changes the chemical parameter by substituting the isocyanate component from expensive 1,5-naphthalene diisocyanate (NDI) to cost-effective diphenylmethane diisocyanate (MDI), while compensating for performance differences through optimized polyol selection and controlled foaming parameters to achieve comparable durability and settling resistance
Solution Approach 2:
The invention replaces the expensive NDI material with a more economical MDI-based urethane raw material, accepting that MDI has different properties but compensating through formulation optimization to achieve sufficient service life for the bumper spring application
2Quantity of substance
If diphenylmethane diisocyanate (MDI) is used as isocyanate component, then material cost is reduced, but durability and strain-induced crack resistance deteriorate
Solution Approach 1:
The invention creates a composite urethane system by combining MDI isocyanate with specifically selected polyester-based polyol and polyether-based polyol in optimized ratios, forming a multi-component system that compensates for MDI's lower durability through synergistic interactions with the polyol components
Solution Approach 2:
The invention applies different polyol types in specific proportions to create regions with optimized properties, where the polyester-based polyol provides structural integrity and the polyether-based polyol enhances flexibility and crack resistance, locally compensating for MDI's limitations
3Ease of manufacture
If skin layer and core portion have different density and foamed cell diameter, then manufacturing process is simplified, but strain-induced cracks occur reducing durability
Solution Approach 1:
The invention optimizes the foaming parameters including temperature (70-130°C), time (2-60 minutes), and raw material composition to control the density ratio and cell diameter ratio between skin layer and core portion, ensuring they fall within specific ranges that prevent strain-induced cracks while maintaining manufacturing efficiency
Solution Approach 2:
The invention establishes feedback control by measuring the density and foamed cell diameter of both skin layer and core portion, then adjusting the foaming process parameters based on these measurements to maintain the optimal ratio relationships that prevent cracking
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 achieves improved durability and settling resistance under high load and deformation while reducing costs, by optimizing the polyol component and production method to ensure similar densities and foamed cell diameters in the skin and core portions, thus preventing strain-induced cracks.
Implementation Method 1
the urethane raw material is heated in the forming mold at a temperature of from 70°C to 130°C for from 2 minutes to 60 minutes to be foamed and cured into polyurethane foam
Implementation Method 2
heated at a temperature of from 70°C to 130°C for from 2 minutes to 60 minutes to be foamed and cured into polyurethane foam
Implementation Method 3
after removing from the forming mold, the urethane molded body is heated at a temperature of from 100°C to 150°C for from 3 hours to 20 hours
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A urethane bumper spring is produced from a urethane raw material containing a polyester-based polyol as a polyol component and diphenylmethane diisocyanate as an isocyanate component, and includes: a skin layer; and a core portion, in which the skin layer has a density (Da) and a foamed cell diameter (Ra), and the core portion has a density (Db) and a foamed cell diameter (Rb). The density (Da), the foamed cell diameter (Ra), the density (Db), and the foamed cell diameter (Rb) satisfy relationships shown in the following expressions: 1.0≤Da/Db<1.34 (1) and 0.53<Ra/Rb≤1.0 (2). Accordingly, the urethane bumper spring can achieve a cost reduction while having durability and settling resistance under high load and high deformation.