Development and application of elastic elements fo

2022-10-18
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Development and application of elastic elements for modern rail transit Abstract: This paper introduces the continuous improvement of several vibration and noise reduction elastic elements and key technologies in modern rail transit

key words: rail transit, elastic components, vibration reduction, noise reduction

overview

with the rapid development of China's railway transportation towards high-speed and heavy load, the vibration and noise problems of locomotives and vehicles are becoming more and more prominent. At present, the domestic countermeasures are:

(1) change the rigid gear drive to elastic drive, change the rigid suspension to elastic suspension, increase the elastic positioning system, and adopt full suspension to improve the high-speed passing performance Reduce structural fatigue

(2) optimize the configuration of elastic parameters of the walking system and improve the "critical speed of snake motion"

(3) increase the "static deflection" and "equivalent boom length" of the suspension system to ensure the balance performance index

(4) on the premise of ensuring the smooth operation of locomotive and vehicle, realize the maximum lightweight of bogie, especially reduce the "unsprung mass" as far as possible and mitigate the wheel rail impact, so as to reduce the construction and maintenance cost of railway

therefore, high-quality vibration damping elastic elements should be widely used to effectively reduce the wheel rail force and improve the running performance of the system. Zhuzhou Shidai New Material Technology Co., Ltd. (hereinafter referred to as Shidai new material) has developed with the development of train speed increase in China. According to the requirements of users, it continues to research and develop new rubber elastic components. At present, the elastic components produced by the company not only have the largest market share in domestic locomotives and vehicles, but also their products are exported to developed countries such as Europe and the United States

1 the existing elastic element products

the rubber elastic elements produced by Shidai new material are widely used in locomotives, passenger cars, freight cars, lines and various engineering machinery devices, mainly for suspension, traction, vibration isolation and cushioning, with a total of more than 500 varieties

2 product improvement work

times new material in 2002, with the support of the national "863" plan and the "Tenth Five Year Plan", actively cooperated with South China University of technology and Beijing University of chemical technology to carry out corresponding research and improvement on the creep resistance of axle box springs, fatigue resistance of flexible joints, and aging resistance of air springs, and made breakthrough progress

(1) creep of axle box spring

Figure 1 axle box spring (left: conical spring, right: V-spring)

axle box spring (see Table 1) is mainly used for the primary suspension of Metro urban rail cars. By adjusting the structure and rubber formula, it can meet the different stiffness requirements in vertical, horizontal and vertical directions at the same time, effectively reduce wear and isolate noise. Due to the large circumferential shear and vertical compression deformation, the creep resistance of products can become the main symbol to measure the technical level. Foreign companies such as Dunlop and phonex have mature technologies, while domestic companies are relatively backward. Taking a certain type of V-shaped spring as an example, the vertical static deflection of its bearing p=3500kg is f=41.2mm, and the creep within 5 years is generally required to be controlled within 20% of the static deflection of the product, that is, 8.24mm. The research shows that the creep of V-shaped spring after 3 days of use accounts for about 70% of the total creep in 5 years. Therefore, the ratio of creep and static deflection of static pressure for 3 days can be used δ To generally evaluate the creep of V-spring. It can be seen from table 1 that when the aircraft crashed into the right engine during forced landing, the 3-day creep of PPS was significantly reduced, even better than that of imported products. Table 1 static pressure of V-shaped spring for 3 days δ Value

2.2 fatigue resistance of flexible joints

Figure 2 flexible joints

flexible joints (also known as rubber ball joints) replace traditional rigid joints in modern locomotives and rolling stock, with the characteristics of reducing vibration and noise, no wear, long life and so on. The key technology of such products lies in the anti fatigue performance. Some joint rubber products with harsh service conditions (large deformation or high frequency) have always been the core products of Companies in the same industry in developed countries. Domestic technology in this regard is relatively backward. Shidai new material has also made many attempts in the past few years, but the results have been not ideal

now, by using the in-situ grafting modification of carbon black and nano composite technology, the fatigue life of products can be greatly improved without changing the original formula. As shown in Table 2, the improved samples not only exceed the American Standard, but also significantly better than the American samples. At present, this work has been recognized by American customers. Table 2 performance improvement of handrickson ball joint

2.3 aging resistance of air spring

air spring (Figure 3) is a low-frequency vibration damping elastic element applied to the secondary suspension of high-speed trains, and its working stroke is completely obtained by the deformation of airbag. When the rubber airbag is used, the inner and outer rubber layers are always in the state of repeated expansion and contraction in the circumferential and radial directions, so the requirements for flexion resistance and flexibility are very high; In addition, the heat generated by severe deformation and internal friction between materials also worsens the service conditions of the rubber and affects the aging resistance of the air spring

Figure 3 several specifications of air springs

after adopting new rubber varieties and supplemented by in-situ grafting modification technology in 2002, the rubber properties fully meet the standards of foreign companies, especially the two main properties of aging resistance and flex cracking resistance, which are significantly higher than the previous formula of new era, indicating that the service life of air springs will be greatly improved. Table 3 performance comparison of air spring rubber

3 several products newly developed at present

3.1 nonlinear shock absorber

this kind of elastic element (see Figure 4) is characterized by no wear, maintenance free, large vertical deflection (greater than 50mm), which can effectively ensure good running comfort under different operating conditions such as empty vehicle, heavy load, low speed and high speed, good vibration isolation performance, three-dimensional stiffness matching, and reducing wheel rail impact and wear, Compact structure, simplify the components of bogie, reduce costs, etc. The nonlinear shock absorber can be applied to the axle box of bogies of freight cars, passenger cars (below 160km/h), Metro, light rail and other vehicles to play the role of suspension, positioning and vibration reduction

Figure 4 nonlinear rubber elastic element

(left: liquid composite spring, right: rolling ring spring)

3.2 anti roll torsion bar system

the anti roll torsion bar developed by new materials in the era (Figure 5) uses rubber joints to replace the original rigid connection, which can effectively isolate the vibration and noise transmission between the frame and the vehicle body. The whole structure is abrasion free and maintenance free. The connecting rod adopts rolling technology, which increases the strength of the torsion bar, The machining process is simplified, and the spline connection with the rotating arm is changed to interference connection. The products are produced in full accordance with UIC standards and have passed the assessment of 10million fatigue loads

Figure 5 anti rolling torsion bar

3.3 elastic clay coupler buffer

elastic clay buffer (Figure 6) was first used in imported military equipment. Through research and development, it has been relatively mature and has been applied to civilian products. This kind of coupler buffer uses unvulcanized silicone rubber that can be compressed as the working medium, which has the advantages of small impedance, large capacity, high absorption rate, small volume, light weight, compact structure, long maintenance cycle (up to more than 10 years), good high and low temperature performance (150200 ℃), good aging performance, and combines the advantages of traditional rubber buffer and hydraulic buffer, overcoming the disadvantages of low absorption rate and complex hydraulic structure of traditional rubber buffer, It can significantly improve the longitudinal comfort of high-speed trains

Figure 6 elastic clay coupler buffer

4 conclusion

rubber based vibration and noise reduction products are widely used at home and abroad at present. Because rubber has unique viscoelastic behavior in a wide temperature range, it can not only absorb and store impact energy through elastic deformation, but also greatly consume energy through the relative movement of molecular chains, so as to improve the environment and ride comfort, This ability is not possessed by any other material. Therefore, reducing the internal and external vibration and noise of rail transit and using high-quality rubber based vibration and noise reduction products is the only way

* National "863 Plan" funded project (2001aa334010) and national "Tenth Five Year Plan" key research project (2001ba310a12)

Author: Zhuzhou Times New Material Technology Co., Ltd. (end)

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