Depending on the braking conditions, improving the graphite structure in the intrinsic organization of the cast iron can reduce the stress concentration phenomenon and prevent the occurrence and expansion of cracks. By
High-speed braking surface temperature of the friction payment is very high, the material should be high-temperature mechanical properties, thermal conductivity, low modulus of elasticity and coefficient of expansion, so that the
Braking heat quickly dissipate to reduce the deformation of the disc body, in addition, the material should have high thermal fatigue strength to improve its life. On the basis of the development and production application of brake discs for speeding buses, we have developed a series of brake discs for buses.
On the basis of speed bus brake disc development and production applications, adjust the chemical composition of creep cast iron, add alloying elements, and its mechanical properties, physical properties, high-temperature mechanical properties and tensile, hot and cold fatigue and other properties carried out a large number of tests. On this basis, the friction performance and braking performance test, synthesize and analyze the results of various tests.
Analyzed the results of various tests, and finally chose a better mechanical properties at room temperature and high temperature, smaller coefficient of thermal expansion, higher coefficient of thermal conductivity and casting
Good process performance, easy to optimize the process and mass production of peristaltic cast iron as the disk material.
Laminating sand casting process is a commonly used casting process for metal products, which effectively molds polygonal metal structures. The advantage of this casting process is that metal parts of any shape and size can be produced. The coated sand casting process is a precise molding method which is done with the help of pressure and temperature. This process can produce metal parts of any shape, it is fast, efficient, good molding effect, high precision, good polish, leek is often suitable for castings that require higher precision.
Coated sand casting process consists of two main components, namely, mold and coated sand. Mold is the casting molding shell, which consists of several pieces of mold, mold structure can be completely closed or inside and outside the opposite structure. Coated sand is a special mortar consisting of vises, sand particles and polymers, which has a good bonding force and facilitates molding.
The process for film sand casting is as follows: First, the mold is filled with film sand, and then the mold is heated to solidify the film sand. Next, the casting is put into the mold, followed by sealing the mold, and then the casting is withdrawn, and after water cooling, the casting is separated by using machine city tools, and finally polished to get the final product.
The advantages of the clad sand casting process are very obvious, it can meet a variety of needs, produce high quality products and stable quality. In addition, the coated sand casting process has good precision and polishing degree, can clip the complex cavity, so that the casting processing quality is higher, more durable.
However, the coated sand casting process also has its limitations. Due to the difficulty of making molds, the cost of mold sand is higher, so the high cost is a major disadvantage of the film sand casting process. In addition, the process equipment is complex, the process is also longer, due to slower production speed, the operation is also more complex, the time required is also longer
The wear of brake discs is mainly caused by high temperature and high stress state during braking process, which is called thermal wear. Charcoal/carbon composite brake discs, with excellent high temperature thermal stability, under the condition of 1200~1500℃, its strength is not only not reduced, but improved, so the high temperature abrasion resistance is good; at the same time, due to the coefficient of thermal expansion is small, the thermal conductivity...
