Composite Brake Drum Structure for Strength and Heat Conduction
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Solution Overview
Problem
Current brake drum materials, such as gray cast iron and vermicular graphite cast iron, face issues with low strength and poor thermal conductivity, leading to material fractures and thermal fatigue, while composite brake drums with low-carbon steel have poor thermal conductivity and rigidity, resulting in deformation and safety concerns.
Innovation Solution
A composite brake drum is developed with an outer layer of high-strength ductile iron and an inner layer of low-alloy gray cast iron, fused through solid-liquid bonding, incorporating a rare-earth ferrosilicon magnesium spheroidizing agent and SiC, and employing an electromagnetic field to enhance bonding and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gray cast iron is used for brake drums, then thermal conductivity is good, but strength is low and material fracture occurs
Solution Approach 1:
The patent uses a composite structure with an inner layer of gray cast iron (for thermal conductivity) and an outer layer of high-strength ductile iron or vermicular iron (for strength and toughness). This composite material approach allows the brake drum to simultaneously achieve good thermal conductivity and high strength, resolving the contradiction between these two properties.
2Strength
If vermicular graphite cast iron is used to improve strength and toughness, then strength is improved, but thermal conductivity deteriorates and process control becomes difficult
Solution Approach 1:
The brake drum is divided into two functional layers: the inner layer (gray cast iron) handles thermal conductivity requirements, while the outer layer (ductile or vermicular iron) handles strength and toughness requirements. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between strength improvement and thermal conductivity maintenance.
3Duration of action of stationary object
If composite brake drum with low-carbon steel is used, then service life is improved, but thermal conductivity and rigidity are poor causing deformation
Solution Approach 1:
The patent employs a composite structure combining gray cast iron (inner layer) and ductile or vermicular iron (outer layer), replacing the low-carbon steel composite approach. This specific material combination maintains excellent thermal conductivity and rigidity while extending service life, resolving the contradiction between service life improvement and maintaining thermal conductivity and rigidity.
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 composite brake drum achieves high strength and thermal conductivity, significantly improving wear resistance and thermal fatigue resistance, extending service life by over 4.3 times and reducing weight by 10%, while maintaining excellent thermal conductivity and strength.
Implementation Method 1
adding 1-1.5% by weight of rare-earth ferrosilicon magnesium spheroidizing agent and 0.8-1.3% by weight of ferrosilicon inoculant at the bottom of a ductile iron ladle for spheroidization
Implementation Method 2
employing an electromagnetic field to enhance bonding and thermal conductivity
Implementation Method 3
the outer layer and the inner layer are fused together by means of solid-liquid bonding
Implementation Method 4
The heat generated by frequent braking causes the temperature of the inner surface of the brake drum to rise sharply, which is followed by rapid cooling due to thermal conduction
Data Source
AI summary
The present disclosure discloses a high-strength and high-thermal conductivity new material composite brake drum and a preparation method thereof. The composite brake drum is composed of an outer layer of high-strength ductile iron and an inner layer of high-thermal conductivity gray cast iron, which are integrated by centrifugal compound casting. The outer layer of the composite brake drum is firstly poured on the production line of iron particle-filled coated sand shells. Due to the fast solidification and cooling of the iron particle-filled coated sand shells, the castings have the characteristics of fine and dense organization structures to ensure the high strength and high toughness of the ductile iron of the outer layer. On this basis, the inner gray cast iron is poured under centrifugal casting conditions, in which a good metallurgical bond between the inner and outer layers is achieved by controlling the centrifugal casting process.