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2019 - 11 - 09
With the rapid development of the economy and the continuous improvement and innovation of the company's fatigue testing machine product research and development technology, our company is constantly expanding the international market and has been recognized by foreign customers.On November 3, foreign agents came to our company's workshop to visit and inspect. Our company Yang always warmly received Southeast Asian customers from afar. The Southeast Asian customers' trip was mainly to visit our company's dynamic fatigue testing machine. Accompanied by the technical director, the customer visit...
2
2019 - 08 - 02
Our company has been studying and exchanging with Professor Huang Peiyan, School of Civil Engineering and Communications, South China University of Technology for a long time. Under the guidance of Professor Huang Peiyan, we have a deep understanding of the durability, fatigue fracture and corrosion resistance of bridge structures. With rich experience, strong technical force and good corporate reputation, Empoda successfully won the bid on July 30 for the project of Creep Load Long-term Performance Testing System, a large-scale environmental simulation cabin of Southeast University Urban Scie...
3
2019 - 08 - 01
Distinguished users:Hello! First of all, thank you for your long-term concern and support for Empoda Industrial Systems Co., Ltd.  This revision includes computer website (www.szenpuda.com) and mobile website (m.szenpuda.com), aiming to further play the role of external publicity and communication of the website, and to provide customers with better service. At the same time, it also shows customers the new look of Enpda's continuous development.Compared with the old version of the website, the new page style is adopted and the whole structure is clearer. But we can't be perfect eith...
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2019 - 06 - 11
Recently, our company has successfully passed the ISO 9001:2008 quality management system certification of Shenzhen Bid Winning International Certification Center. It marks that our company has stepped into a standardized, standardized and scientific track of modern enterprise management.The certificate of ISO901:2008 quality management system certification is the standardized and standardized comprehensive inspection of the company's various management work, and an important guarantee for the company's sustained, stable and healthy development. We will further optimize and standardize various...
5
2019 - 05 - 29
Our company has developed a batch of 100KN electro-hydraulic servo dynamic fatigue testing machine and 20000N.m micro-computer controlled torsion testing machine for Wuhan University of Technology, which have passed the user's acceptance successfully. As a supplier of the State Key Laboratory of Silicate Building Materials, these test equipments are mainly designed to meet the requirements of composite materials. The coaxiality requirement of the test machine is very high when dynamic fatigue testing is done. The deviation between upper and lower fixtures is within 0.1 mm in the whole range of...
6
2019 - 05 - 21
On May 18, Enpuda delivered another batch of hydraulic silent servo oil source system equipment to Taiwan's agents to help Empoda successfully gain access to the Taiwan market and lay a solid foundation.The key technology of hydraulic servo cylinder controls the minimum displacement loading of 1 micron/s, and the maximum noise of silent servo oil source is less than 62 decibels. Users come to our company for acceptance on the spot and use calibration instruments to measure all the indicators meet the requirements.This is the second cooperation after the success of the last project. It is a hig...
7
2018 - 11 - 01
In October 2018, a teacher from Shijiazhuang Railway University came to our company to make a technical discussion on the 'Rail Rolling Contact Fatigue Test Bench'. After more than one year's exchange of theoretical and practical experience between the two sides, and consultation with relevant experts from Southwest Jiaotong University and China Academy of Railway Sciences, the project has been deeply understood and discussed; for dynamic fatigue test-bed, multi-channel coordinated loading test-bed, rail rolling contact fatigue test-bed. The technology of wheel-rail fatigue test-bed is deeply ...
8
2018 - 06 - 14
On June 20, our company, together with Southwest Jiaotong University Railway Development Co., Ltd. and Hong Kong Polytechnic University, completed the most critical test in the project of 'High-speed Railway Turnout Safety Monitoring System'. Rail fracture signal acquisition and validation under natural frequency and load applied by dynamic fatigue test bench. In the course of two years'research in more than a dozen relevant experimental centers in China, they finally reached a cooperative relationship with our company.Dr. Wang of Hong Kong Polytechnic and Zhang Gong of Southwest Jiaotong Univ...
9
2018 - 05 - 29
In this hot May, Empoda brought you good news. Successfully won the bid on May 18 - In 2017, the central government guided the local science and technology development special fund project 'Guizhou Highway Engineering Inspection and Inspection Technology Innovation and Service Platform Construction' inspection equipment procurement project.The leadership of the bidding company attaches great importance to the bidding documents, technical quality and other specific requirements. Due to the time constraints and heavy workload, under the leadership of the department, colleagues worked together to...
10
2018 - 03 - 25
In March of spring blossom, after a month of basic information collation, various department managers organization and coordination, ushered in the Enpda ERP project officially successful online operation. It also marks a big step forward in the internal management of the company in the new year.Enpuda ERP system operation project is an important measure to improve company management and control, optimize resource allocation, enhance core competitiveness of enterprises, and promote enterprise management and development. The project has received the attention and support of company leaders and ...

Study on application of the rail grinding on controlling the corrugation in metro

Date: 2020-01-07
Views: 4

Study on application of the rail grinding on controlling the corrugation in metro

DU Xing,GUO Jun,CHEN Jing,CUI Da-bin

( School of Mechanical Engineering , Southwest Jiaotong University , Chengdu 610031, China )Abstract : This paper introduces the existence of the domestic rail transport rail-shaped surface of the wheelmatches the situation and problems. The dynamic analysis model of metro vehicle is set up by automateddynamic analysis of mechanical system SIMPACK software. Firstly, used preprocess of the SIMPACK dealwith the standard rail profile and design of rail profiles and the field lines and measured data input thesimulation model. Secondly, the vehicle dynamic response is analyzed after the rail grinding, which iswheel-rail lateral force, vertical force and derailment coefficient. Compared the wheel surface and measuredthe same uneven track conditions, the use of standard rail profile and design of rail profile of the dynamicresponse of the MTR EMU. The results show that the same excitation conditions, the use of the design railprofile of the wheel-rail vertical force, lateral force greatly reduced.

Key words : rail grinding ; profile design; rolling contact fatigue; vehicle-track coupling dynamic

With the rapid development of China's economy, the period of continuous urban development. Urban rail transit has been widely used in China. The development of urban transport in China has become the core and key development of urban development. At the same time, the problem of wheel-rail contact has also become more prominent. Therefore, China's urban rail transit has entered a fast-moving, steel rail profile It is one of the key factors in the wheel-rail system. It is not only related to the dynamic performance of the vehicle, but also to the contact between the wheel and the rail. Choosing a good rail profile can not only improve vehicle dynamic performance, but also greatly reduce wheel-rail contact stress, reduce wheel-rail maintenance costs, improve vehicle safety and comfort, and extend the service life of the rail due to long-term A single vehicle, uniform axle weight, and the same curve section are operated at the same speed, so rolling contact fatigue cracks on the surface of the rails appear, peeling off blocks, side wear of the rails on the curve, and top surfaces of the rails under the curve The typical damage pictures of wave grinding, rail head crushing, uneven welding joints, and fat edges of inner rails are shown in Figure 1. These injuries seriously affect the safe operation of the vehicle and affect the ride comfort of the vehicle.


Study on application of the rail grinding on controlling the corrugation in metro

The research question of rail grinding profile is a very complicated and urgent problem in railway maintenance engineering.

Whether it is resolved directly affects the rapid development of rail transit. In this paper, the multi-body dynamics software SIMPACK is used to establish the dynamic model of the subway vehicle. The response of the standard rail profile and design to the vehicle system dynamics under simulated track irregularities is simulated and calculated.

1. Model introduction The multi-body dynamics software of pure commercial railway mainly includes Adams / rail and SIMPACK, and some other few programs. Among them, the current SIMPACK market share is 49% and the Adams / rail market The occupancy rate is only 15%. SIMPACK can analyze the vibration characteristics of the entire vehicle system, the stress conditions of each component, acceleration, and displacement. The orbit module was developed by the German Aerospace Center (DLR) in summary of 20 years of wheel-rail contact simulation experience and modern advanced simulation technology.

1.1 Advantages of SIMPACK

(1) The new wheel-rail contact model is adopted. The kinematic constraint calculation method can effectively improve the calculation speed of dynamics. Using Kalker's simplified linear rolling contact theory, SIMPACK comes with a highly automated wheel-rail contact linearization model that can be verified by a large number of experiments. That is, equivalent linearization and co-function linearization.

(2) The differential equation is automatically established to facilitate error checking.

In vehicle system modeling, it is not necessary to establish differential equations. The program automatically generates differential equations based on the model's topological relationship, which is convenient for finding errors in the model. It is easy to build models.

(3) Achieve effective data post-processing results.

SIMPACK has strong data post-processing capabilities, and uses animations, charts, and other forms to output results intuitively.

1.2 Vehicle model

The vehicle system model consists of a car body, two frames, and four wheel rails. Each component is considered as a rigid body. The rail profile data has a special pre-processing program to achieve it, and the spline function is used to fit the cross-sectional profile. The measured data and design profile data can be processed into simulation data. To model the suspension system, different connection points are set on the wheel rail, frame and car body, respectively, as the starting and ending coordinate points of the suspension system, and the spring and damping force elements of the suspension system are established at the same time. The vehicle body modeling only needs to input the coordinates of the length, width, height and mass of the vehicle body, the moment of inertia, and the height of the center of mass. As for the wheel-rail contact model, two different forms of models are mainly used in the wheel-rail model: the elastic-rigid or rigid-constrained wheel-rail contact model. This article uses the rail-constrained wheel-rail contact model. The specific vehicle model is shown in the figure.

Study on application of the rail grinding on controlling the corrugation in metro


2 evaluation indicators

In this paper, the derailment coefficient without considering the action time is used as the main evaluation index. The analysis of the derailment coefficient is mainly directed to the case where the wheel-rail lateral forces H> 0 and H = 0. The derailment indicators for evaluating wheels in different situations are derived from the wheel force balance conditions. Nadal proposed that the derailment coefficient is the ratio of the lateral force Q and the vertical force P acting on the wheel at each moment.


Study on application of the rail grinding on controlling the corrugation in metro

Where Q is the lateral force acting on the wheel rim; P is the vertical force acting on the wheel; a is the wheel rim angle; μ is the friction

Rub coefficient. Because the rim angle of the wheel of our vehicle is 68 ° ~ 70 °, and the friction coefficient is 0.20∪0.30, when the allowable limit of the derailment coefficient is determined, the upper limit of the friction coefficient is 0.3000.35. According to the national standard 'Specifications for Evaluation and Test Evaluation of Railway Vehicle Dynamic Performance' (GB5599-85), in order to prevent derailment, the derailment coefficient of the vehicle should meet the conditions:

Study on application of the rail grinding on controlling the corrugation in metro


3 results and analysis

The parameters selected in the calculation model: the track gauge is 1435 mm, the track bottom slope is 1/40, the wheel profile is LM, and the vehicle is a subway vehicle in some place in China. The simulation model was used to compare and compare the dynamic response of the subway train vehicle with the front and back of the rail-grinding model. The important index for evaluating derailment was France. Nadal's derailment coefficient. Taking into account the above factors, this article discusses the 60km / h pass curve The impact on the derailment coefficient of the vehicle, the vertical force of the wheel and rail, and the lateral force of the wheel and rail during the segment. The curve parameters are a curve radius of 800 m, a front straight line of 150 m, a relaxation curve length of 55 m, a super height of 75 mm, and a total curve length of 670 m. The curve disturbance is the measured rail wave grinding rail disturbance.

3.1 Rail profile input

This model uses standard CN60 rails and designed steel and rail profiles, as shown in Figures 3 and 4. The model uses asymmetrical grinding. HS curves are used for curved outer rails, and CPL treads are used for inner rails. For standard treads, the same tread is used.


Study on application of the rail grinding on controlling the corrugation in metro


The rail grinding design profile used in the model is based on the wheel-rail contact combination feature design. Factors such as wheel-rail base point and rolling circle radius are mainly considered.

The line disturbance used in the model is a domestic subway line and also the line operated by the vehicle parameters.Among them, before the grinding, that is, the line disturbance under relatively severe conditions is shown in FIG. 5.

At the same time, it was also measured that the disturbance on the surface of the rail after grinding was smoother than that before grinding, and there was no large peak. See Figure 6 for details.

Study on application of the rail grinding on controlling the corrugation in metro

Study on application of the rail grinding on controlling the corrugation in metro



3.2 Analysis of results in the presence of disturbances

Parameter input in the model, input the standard CN60 rail and the design profile before and after the grinding, and the speed is set to 50m / h without the disturbance, the 1-4 wheel wheel traverse amount comparison. It can be seen from Figure 7 that under the condition of no disturbance, the traverse amount of using the design profile is different from that of the standard CN60 rail by 2.3 mm, that is, using the designed rail profile at the same speed can increase the rolling circle radius. Poor , when the vehicle passes through the curve, it can provide sufficient centripetal force to improve the self-steering ability of the vehicle through the curve. Reduce the lateral force of wheel-rail interaction, and reduce rail angular contact fatigue and excessive wear caused by excessive wheel-rail lateral force.

Study on application of the rail grinding on controlling the corrugation in metro


In the presence of disturbance, the comparison of the maximum derailment coefficient before and after grinding is shown in Figure 8. Comparison of derailment coefficients before and after grinding. It can be seen from the figure that before and after grinding, the derailment coefficient and grinding after wavy wear of the rail are eliminated

The derailment coefficient before is basically the same, except that some wheel sets are smaller than the derailment coefficient before grinding. The author believes that under the condition that there is no large track disturbance, because the model is set in the track, the straight section also adopts the rail profile design of the curved section design, which may cause a large wheel pair impact after entering the curve, thereby Generates a large derailment factor.

Figure 9 shows the dynamic calculation results after 1 day, 24 days, 57 days, 92 days, and 142 days after grinding, respectively. Dynamic simulation was performed on the measured track irregularities, and it is not difficult to see in the figure, In the 24 days after grinding, the vertical force of the wheels and rails increased rapidly, and after this period of time, after 57 days, the vertical forces of the rails were greatly reduced and restored to the level just polished. And there is a downward trend. The results obtained by the dynamic simulation are consistent with the results obtained by the later observations. During this period, the rail wave bounces faster, then enters a relatively stable period, and the wave depth decreases.


Study on application of the rail grinding on controlling the corrugation in metro


Because the hardness of the rail parent body of this line is between 250 ~ 270HB, it has a softer material. After the surface of the rail is polished, the rail parent body is exposed. At the same time, the hardness of the wheel is about 320HB, so After rolling for a period of time, a certain degree of sexual hardening occurred on the surface of the rail, and at the same time, wave-shaped wear occurred due to the mismatch of the types of sleepers used.

4 Conclusion

By comparing the dynamic indexes of the standard profile and the designed profile at different speed levels and orbital excitation conditions at different periods, the following conclusions can be drawn:

(1) The use of asymmetrical design profiles in the grinding of curved rails can effectively improve the contact state of the wheel and rail. The material of the wheel rail tread can withstand load and the frequency is relatively reduced. At the same time, the service life of the wheel and rail can be extended.

(2) The use of asymmetric rail profiles on the curves under different excitation conditions is more conducive to the vehicle's curve passing, which can effectively reduce the wheel and rail lateral and vertical forces. It is effective in the presence of disturbances. Reduce the derailment factor.

(3) In different periods of development of wave grinding, the use of rail grinding on rails can effectively reduce the wheel-rail interaction force, and control

The rapid rebound of the wave-grinding mill prolongs the rail grinding cycle, thereby saving costs.


references:

[1] Jin Xuesong and Liu Qiyue. Wheel-Rail Tribology [M]. Beijing: China Railway Publishing House, .2004.

[2] Jin Xuesong, Du Xing, Guo Jun, Cui Dabin Research Status of Rail Grinding Technology [J]. Journal of Southwest Jiaotong University, .2010, (1): 1-10.

[3] Liu Xueyi. Preliminary Study on the Effect of Asymmetrical Grinding Technology on Slowing Rail Side Grinding [J]. China Railway, 1993, (10): 12-14.

[4] Guo Jun, Liu Qiyue, Wang Wenjian Effect of rail grinding on wheel / rail rolling contact spot behavior [J]. Railway Construction, 2009, (12): 92-94.

[5] E. Megel, M. Roney, P. Sroba, The blending of theory and practice in modern rail grinding [J]. Wear, 2002, 253 (10): 308-316.

[6] Joe Kalousek, Peter Sroba, Hegelund C. Analysis of RailGrinding Tests and Implications for Corrective and PreventiveGrinding [C]. Proceedings of the 4th international heavy haulconference, Brisbane Australia, 1 989.

[7] Sudhanshu Sharma, Positive Results From Rail Grinding in India [J]. International Railway Journal. 2004, XLIV (5): 41.

[8] Huo Huihui, Chen Guoqing. Damage and grinding technology of rail tread [J]. Railway Science, 1991, 13 (9): 105-1 10.



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