Train slow spring preset and discussion

Collision and impact of a single mine car on the line brakes. When a single mine car is blocked by a car stop, the collision and impact between them can also be considered as a positive collision of two elastomers, and the line stop is generally Installed on the track or on the road, it can be regarded as a mine car colliding with another mine with infinite mass. Then the impact force is Pmax1/∝=v0(C0m/2)1/2(1) where the maximum collision (impact) force between the Pmax1 mine car and the car stop is C0. The rigidity coefficient of the mine car and the car stop (hypothesis) the same)

m mine car mass v0 before the collision of the speed of the mine car according to the law of conservation of momentum m1v1 + m2v2 = (m1 + m2) u in the formula m1, m2 for the quality of the first and second miners respectively u = (m1v1 + m2v2) / ( M1+m2) The kinetic energy of the system when the mine car is in contact (before collision) is T0=(m1v12+m2v2)/2 The kinetic energy of the system at the end of the first phase is T1=(m1+m2)u2/2 The kinetic energy difference T=T0-T1 is the first collision The change in system kinetic energy during the phase, ie

2mmvvmm denotes the relative movement speed of the two mine cars at the beginning of the collision with v0, that is, v0=v1-v2 then T=2120122mmvm(2) because the pre-collision car stop (installed on the ground, the mass is equivalent to infinity) is at rest, ie M2→∞, v=0, then u=0. This indicates the end of the collision at the end of the first phase, but at this time the kinetic energy of the system is not all converted into the internal energy of the system, that is, the buffer spring does not absorb all of its kinetic energy. And most of the kinetic energy is converted into heat and sound energy, as well as the residual surface deformation of the colliding object is lost. After that, the internal energy of the system may be released again (the second phase of the collision), and even a second collision (which is much smaller than the first collision). For this reason, when calculating the change of the kinetic energy of the system in the first stage, it is necessary to introduce a loss coefficient ξ1, that is, the formula (2) becomes T=21210122mmvm=2102mv and then introduces the coefficient ξ2 (considering the spring in the car stop, the claw axis The deformation work and the friction work between the motion pairs, the actual compression coefficient of the spring) is substituted into the formula (1) and reduced to Pmax1/∝=ξ1ξ2v0(C0m/2)1/2=ξ1ξ2v0(Cm)1/ In the 2(3) formula, the mass ξ1 loss coefficient of a mine car, the actual bearing energy conversion factor of 1/2 ̄ 1/3 ξ2 spring, the total rigidity coefficient of the 0.7 ̄0.9C mine car and the car stop system, C=C0 The impact (collision) of the /21.2 train on the line stop is calculated as follows according to the head of the mine-blocking car and the wheel of the resistance.

The impact force when the car blocker meets the head (with a buffer device) assumes that the ratio of the total stiffness coefficient C of the blocker spring to the stiffness coefficient C0 of the single bumper spring of the mine car is j, ie C=jC0, then: (1) The first mine car only compresses a pair of springs (the contact spring and the brake spring). The total stiffness coefficient of the system is C=[j/(j+1)]C0, and the impact force is obtained by formula (3). Pmax1/∝=ξ1ξ2v0[j/(j+1)]1/2(C0m)1/2(2) The second mine car compresses two pairs of springs with a total stiffness coefficient of C=[j/(3j+1)]C0, Therefore, the additional impact force of the second mine car to the car stop is Pmax2/∝=ξ1ξ2v0[j/(3j+1)]1/2(C0m)1/2(3). The third mine car compresses three pairs of springs. The total stiffness coefficient is C=[j/(5j+1)]C0, so the third mine car attaches the train to the car to the car before the car is blocked. In this case, the car is blocked. A straight track can be set. Generally v0=0.5 ̄0.8m/s is suitable (small tonnage mine car takes a larger value).

The front rail of the compound anti-vehicle has a starting slope (i-re-start), the train stops in front of the double-type vehicle, and the double-stopper acts (opens) during the change of the train. The train slides along the starting slope until the complex resistance is blocked. Speed ​​is

V0=[v2 initial +2gL (i re-listed-w heavy) ‰] 1/2 (6) in the initial velocity of the v2 initial slip, the m/sL mine car self-slip distance, about two pairs of duplex brakes The distance of the pawl. For the 2m3 mine car L≈3m; for the 0.5 ~ 1.2m3 mine car L≈3 ~ 4mi re-listed = (2 ~ 2.5) w weight, for the 2m3 mine car, take i re-listed = 15 ‰; for 0.5 ̄ The 1.2m3 mine car takes i re-listed = 20‰. Substituting the above values ​​into the formula: for a 2m3 mine car, v0=0.72m/s; for a 0.5~1.2m3 mine car, v0=0.8~0.88m/s.

In summary, for a train of 2m3 mine car, v0=0.6m/s; for a train of 0.5~1.2m3 mine, v0=0.7 Ì„0.8m/s.

Optimized design of buffer spring for line blocker 3. The train line stop of 3.12m3 mine car assumes that there are up to 14 heavy mining vehicles and v0=0.6m/s in the train, which is determined according to the General Design of Narrow Mines for Metallurgical Mines. The 2m3 mine car has a spring-buffered contact with a spring stiffness coefficient of C0=350kg/cm (d=20mm, D=80mm, n=9 turns, material is 60Si2Mn), and assumes that the car stop has two springs in parallel Arrangement.

When j=1, C0=350kg/cm(1) The maximum impact force of the train on the line stop is obtained by the formula (5) ∑ Pmax14/∝=ξ1ξ2ξ3v0(C0m)1/2=6350kg, take ξ1= 0.55, ξ2=0.8, N=14 vehicles, get ξ3=4.87, m=G/g, G=6880kg (2m3 mine car weight), C0=35000kg/m.

(2) The spring material is 60Si2Mn, [τ]k=750MPa, and the spring index C=4, then K=1.37, so the spring wire diameter is dmax=1.6(KPmaxC/[τ]k)1/2=2.43 In the cm type, Pmax is the maximum impact force per spring of each paw, Pmax=(∑Pmax14/∝)/2=6350/2=3175kg, so the maximum deformation after compression of the spring is λmax=Pmax/(C/ 2) = 18.2cm Obviously this value (λmax = 18.2cm) is slightly larger, but the spring can obtain a suitable amount of deformation by adjusting the ratio.

Conclusion Under the same conditions, the impact of the mine-blocking car is smaller than that of the resisting wheel, so the size of the spring is also small.

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