Mining electric locomotive bakelite hand wheel brake shoes Brake Linkage Robust Design

手轮闸瓦制动连杆机构中,转动副连接着拉杆、制动杆和传动杆并允许相互间有相对运动,故转动副需要有一定的间隙,连杆机构间">In the mining electric locomotive bakelite hand wheel brake shoe linkage , the rotating pair connected rod, brake lever and gear lever and allow relative movement between each other , so the need to have a certain rotation Vice gap between the linkage multiple rotating vice brake shoe clearance led to uncertainty error in recent years , scholars uncertainty surrounding linkage analysis and robust design parameters studied were as follows : to establish a manufacturing error of the plane even considered based on fuzzy theory bar mechanism robust optimization model ; proposed considering computerized embroidery machine needle bar position precision manufacturing tolerances of the mechanism analysis above research work focuses on consideration of the impact of manufacturing errors on the positional accuracy of the linkage rod comprehensive analysis of the size and movement . random variation Vice gap and made a general method bodies robust design ; proposed gap car steering linkage of robust optimization model with ; HECtoR considerations affect the application of genetic algorithms to optimize the noise factor of the design in multivariable systems ; establish embroidery needle bar mechanism rod length error and joint clearance displacement accuracy of the needle bar linkage effects robust optimization design method ; these studies contain a comprehensive analysis of the three kinds of long rod manufacturing errors and the impact of joint clearance linkage model . taking into account the impact of manufacturing errors linkage rod length and deputy campaign clearance , effectively reducing the linkage motion uncertainty significantly improve the accuracy of motion linkage mechanism .
        Based on the above research work, in order to mine electric locomotive bakelite hand wheel brake shoe linkage for the study, first of all, an analysis of the proposed mining electric locomotive movement bakelite hand wheel brake shoe Linkage establish kinematic model shoe brake linkage under ideal conditions . then consider turning the institution deputy gap kinematics analysis, kinematic model shoe brake linkage model included Vice rotation last to institutions rod length as design variables to turn the vice- gap , the gap Vice contact angle and the processing error bars for the noise factor , and establish a shoe braking distance error of the mean and standard deviation minimization goals mining electric locomotive bakelite hand wheel brake shoe brake linkage parameter robust design optimization model , and use of genetic algorithms and Monte Carlo simulation method for robust parameter design and optimization.
        1 bakelite hand wheel brake shoe brake linkage kinematics modeling 1.1 shoe brake linkage described the driver as shown in the cab driven by a bakelite hand wheel by controlling a balancing pole in Figure 2 and lever 3 , the force transmitted to the brake lever 4 , and finally to achieve the wheel brake shoe pressed .
        1.2 Kinematic analysis and modeling of mining electric locomotive Figure 1 bakelite hand wheel brake shoe brake linkage simplifies the implementation shown in Figure 2 for the rod KA , AB for the front brake lever , BC for the drive rod , CD for the rear brake lever , GD and GE rod rack , K point of convergence point rod and balanced rod ; A, B, C, D, E, K for the pin connection, D, E, K3 Office pin is connected with the body , the movement of the link only consider a, B, C3 of the rotation pin vice .
        Let the car track forward in the positive direction of the x-axis , the brake shoe and the wheel perpendicular to the wheel-rail contact point for the y -axis direction in the positive direction , the establishment of the coordinate system , shown in Figure 3 . Rod moves to the right under the action of the force F , S K represents the point in the x direction and the horizontal pin D of the distance , by comparing the point K before the brake can be obtained from the variation ΔS bakelite hand wheel rotation angle of the brake shoe spacing relationship.
        Shown in dashed A'B'C'D indicates the position of the brake linkage movement before mining electric locomotive bakelite hand wheel brake shoe brake mechanism is shown in Figure 4.
        2 Turn the deputy models included bakelite hand wheel brake shoe 2.1 rotational kinematics modeling linkage model of rotating deputy vice- model pin holes due to manufacturing errors , the pin hole will produce eccentricity RC, set the pin and shaft set radius Ri and Rj, thus turning deputy gap RC = Ri-Rj. located rotating pair meets in continuous contact on the assumption that the pin holes and always keep in touch , do not appear suspended in the shaft hole in the case , because the size of pin holes were normally distributed , so obviously RC also normally distributed . inability to determine the rotation axis of the hole Vice contact position , and therefore can be considered as the contact angle α between [0,2 π] uniformly distributed .
        Models included in the rotation Vice linkage diagram 2.2 Kinematic analysis and modeling agencies will turn 6 deputy model into mining electric locomotive bakelite hand wheel brake shoe brake linkage , then turn the vice models included linkage to simplify the movement shown in Figure 6 .
        The rotation mechanism comprises three pairs, into a continuous contact model : it is considered as a gap imaginary massless rod length equal to R, the direction of the lever is determined by the contact point of the pin and sleeve position, direction of change, available contact angle α said .
        2.3 Vice contact angle gap theory based on continuous contact , currently the vice- range linkage clearance contact angle are set in [0,2 π] uniformly distributed between , closer to the actual circumstances in order to reduce the contact angle of rotation range deputy , for transmission to simulate the process of linkage .
        Let A place for the front brake lever linkage pin hole and tie , B for the front brake lever at the link pin hole and tie , C Department of the link pin with the assumption that the contact angle of the hole with the brake lever , three sports trend do the following assumptions :. φi of position angle linkage , Ri is a gap , αi is the contact angle of rotation deputy uniform intervals according to the direction of movement of bodies in contact angle can be simulated : rod moves to the right at the A contact angle of the active lever pin member is changed to range -90 ° ≤ α1 ≤ 90 °; move on B, the contact angle at the C2 , the link to the left , the range of variation can be lent to 0 ° ≤ α2 ≤ 180 ° , 0 ° ≤ α'3 ≤ 180 °. α1, α2, α3 , respectively, a, B, C3 of the turning angle of the auxiliary contact pin , wherein α'3 = α3-π, then 180 ° ≤ α3 ≤ 360 °.
        3 bakelite hand wheel brake shoe brake linkage Robust optimization design parameters
        3.1 shoe brake linkage examples
        Description for a particular model produced 8t mining electric locomotives for the study, rod length l1 = 910mm, l2 = 795mm, l3 = 280mm, l4 = 210mm. Brake shoe and wheel gap t adjustable range is 3 ~ 5mm, shoe clearance is provided 4mm, then the G range and moving distance of the brake lever after the brake lever is obtained angle φ2 changes in the horizontal direction is 0 ≤ G '≈ G ≤ 11.7mm, 88.9 ° ≤ φ2 ≤ 90 °
        3.2 Robust Design Optimization
        Model consists of ( 8), the mean is set Δt μF, standard deviation σF, based on sound design principles, the mean and standard deviation Δt characteristics all have a small hope , the above analysis , robust optimization design model shoe braking distance of which can be established with regard to the calculation of the standard deviation σF by ( 7 ) we can get the rod length l, turning and turning , deputy vice- gap R contact angle α deteriorate μF = 16Σ 6K = 1 ((t0) K-tK). are trace , and t with l, R and α vary continuously, it can be a nonlinear function t (l, R, α) using a linear method to calculate : the nonlinear function means controllable and uncontrollable factors means factors expanded into small areas within the Taylor series , and an order entry errors as a first approximation spent order terms , the objective function F consists of two parts : the first part of the role is to make the error of the mean braking distance error shoe mean values ​​as close to the ideal sport to improve the motion accuracy desired brake shoe linkage ; second part of the standard deviation of the role is to minimize the error standard deviation shoe braking distance to expect the process to reduce brake shoe uncertainty probability β should satisfy the constraint value , β1 = β2 = 1, the weight coefficients ω1 and ω2 is generally determined by the designer .
        3.3 Results and analysis of the genetic optimization algorithm robust optimization design model of the above shoe braking distance . Various design variables and the initial distribution of the noise factor of the selected parameters , see the selected weighting factor, taking ω1 = ω2 = 100, population size is set to 40 cross was 0.9 , the variation rate of 0.3 basic genetic algorithm process is shown in Figure 8 .
        Comparison of absolute error before ( 1 ) optimize the braking distance t of the shoe according to the parameters in Table 2 after 50,000 times by Monta Carlo simulation were obtained before and after optimization shoe braking distance error of the mean, get all bakelite hand rotation angle θm (m = 1,2, ..., 6) at a distance error of the mean braking , and the obtained solution θm of the two kinds of error and the absolute value of the ideal calculated results . by comparison shoe system mean dynamic linkage reduces the braking distance error of 15.4% , the motion characteristics optimized mining electric locomotive bakelite hand wheel brake shoe brake linkage is more close to the ideal state.
        Comparison of the standard deviation of the front and rear brake shoe braking distance t ( 2 ) optimization parameters in Table 2 by 50,000 times Monte Carlo simulation method were calculated for each θm robust optimization solution and braking distance at standard deviation calculation results Figure 10. by comparison , standard deviation brake shoe from the brake shoe linkage error is reduced by 28.6% , the smaller the smaller the standard deviation of random fluctuations in the amount of braking distance t of the shoe , i.e., even lever mechanism better braking performance robustness .
        4 Conclusion
        ( 1 ) By analyzing the movement of the brake shoe brake linkage established shoe kinematic model of the ideal state of the brake linkage ; consider the effect of turning Vice gap , included the establishment of a shoe model rotation deputy kinematic model of the brake linkage ; for more in line with the actual situation , the contact angle of rotation to simulate deputy , narrowing the scope of the change in contact angle rotation deputy .
        ( 2 ) Consider the brake linkage rod shoe manufacturing error and rotating pair gap , turn affect the contact angle of vice , established a shoe braking distance error of the mean and standard deviation minimization goals mining electric locomotive bakelite hand wheel brake shoe brake linkage parameter robust design optimization model , the use of genetic algorithms and Monte Carlo simulation method for robust parameter design and optimization results show that the shoe brake linkage error of the mean braking distance reduction little by 15.4 % with a standard deviation decreased 28.6%.
        Under the premise of not improve manufacturing precision , through robust design effectively reduces the braking distance uncertainty shoe , designed to improve the quality of mining electric locomotive bakelite hand wheel brake shoe brake linkage has important significance.