Railway Brake Block Composition for Low-Noise Cast-Iron-Level Braking
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Solution Overview
Problem
Cast iron brake blocks for railway vehicles suffer from large wheel rolling noise, large brake noise, and heavy weight, necessitating a replacement material that maintains or improves required properties such as friction coefficient, heat resistance, and wear resistance while reducing noise and weight.
Innovation Solution
A brake block using a synthetic resin-based friction material with a combination of scale-like graphite and granular graphite in specified proportions, along with optional cashew dust or rubber dust, to achieve a decreased friction coefficient comparable to cast iron-based materials, ensuring braking performance under dry and wet conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cast iron-based friction material is used, then braking performance and wear resistance are maintained, but weight increases and noise increases
Solution Approach 1:
The patent uses a composite friction material consisting of sintered alloy base material combined with specific graphite components (scale-like graphite and granular graphite) in controlled proportions. This composite structure achieves cast iron-level friction coefficients while reducing weight by approximately 30% compared to traditional cast iron brake blocks, directly resolving the contradiction between maintaining braking performance and reducing weight.
2Reliability
If cast iron-based friction material is used, then braking performance is maintained, but brake noise and wheel rolling noise increase
Solution Approach 1:
The patent controls the particle size distribution and morphology of graphite components within specific ranges (scale-like graphite: 1-20 μm, granular graphite: 50-200 μm) and their blending ratios (2-8% by mass). These parameter optimizations reduce brake noise and wheel rolling noise while maintaining friction coefficients comparable to cast iron, effectively resolving the noise issue without sacrificing braking performance.
3Weight of moving object
If synthetic resin-based friction material is used, then weight and noise are reduced, but friction coefficient becomes too high
Solution Approach 1:
The patent introduces graphite components (scale-like graphite and granular graphite) as intermediary substances within the synthetic resin-based friction material. These graphite particles act as friction modifiers, reducing the inherently high friction coefficient of synthetic resin materials to levels comparable with cast iron, while preserving the weight and noise advantages of the synthetic resin base material.
4Reliability
If graphite content is increased to reduce friction coefficient, then braking properties improve, but material strength and structural integrity deteriorate
Solution Approach 1:
The patent employs different graphite morphologies (scale-like and granular) with specific size distributions in different proportions within the friction material matrix. This local quality differentiation allows optimal friction control at the contact surface while maintaining overall material strength and structural integrity, achieving a balance between braking properties and mechanical strength that uniform graphite addition cannot accomplish.
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 brake block effectively reduces friction coefficient and noise while maintaining braking performance, allowing for easier operation and replacing cast iron blocks without requiring significant changes in driver technique, and exhibits improved crack resistance and cleanability.
Implementation Method 1
a wheel tread brake device of bringing a friction material into press contact with a wheel tread to generate a friction force and utilizing the friction force as a braking force
Data Source
Figure 1
AI summary
Provided is a brake block including a friction material whose friction coefficient is decreased to the same level as in a cast iron-based friction material while ensuring braking properties under dry and wet conditions and a method for producing the same. The brake block I includes a friction material 3 including a scale-like graphite and a granular graphite in an amount of 20 to 30% by volume in total. The brake block I is produced by a production method including: a preforming step of subjecting a frictional material composition including a scale-like graphite and a granular graphite in an amount of 20 to 30% by volume in total to pressure forming, thereby obtaining a preformed body, and a heat compression forming step of putting the preformed body into a thermoforming mold, and overlaying a back plate thereon, followed by performing heat compression forming, thereby obtaining a brake block I having a desired shape.