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Determination of the pushing pressure of the hydraulic cylinder of the full face roadheader

abstract the movement of the full face roadheader during operation is mainly composed of the forward movement of the body driven by the hydraulic cylinder and the rotation of the cutter head driven by the rotating motor. The propulsive force of the driving hydraulic cylinder of the roadheader is the main design parameter to determine the number and size of the driving hydraulic cylinder of the roadheader, and it is also the basis to determine the propulsive force in the work of the roadheader. In this paper, the commonly used pressure formula of hydraulic cylinder is modified

key words: full face roadheader propulsion cylinder pressure

it is generally believed that the propulsion force of the roadheader propulsion hydraulic cylinder is the sum of the radial average load acting on each blade of the disc-shaped hob and the axis of the machine and the host machine forms an inclination angle. There is a gap between the actual rock excavation and the theoretical calculation. Therefore, the calculated results of the two parts differ greatly from the measured values, and the calculated hydraulic cylinder thrust pressure differs by an average of 18% from the directly measured values. Considering the actual operation factors, the calculated results are quite close to the measured values

1 calculation of hydraulic cylinder pushing pressure

the sum of the average radial load acting on a total of M disc hobs and the friction resistance between the machine and the wall is:

f=un0+*pyn=f0+*pyn

where F0 - the empty pushing resistance when the machine face is empty from the working face and the hob is not working, F0=un includes the sliding friction between the movable frame and the fixed frame

n0 - the vertical support force between the machine and the wall

u - the relative sliding coefficient between the machine and the wall

m - the number of blades actually installed on the cutter head

pyn - the average radial force acting on the nth blade. The average radial force py received on the blade is quite consistent with the actual measured value:

py=0.8952*c+2.2888*ch

, The average radial force py is the measured component force of the vertical hob shaft. * - Rock compressive strength, kn/cm2 H - driving footage per revolution, mm/r

assuming that the average radial force on each blade is equal, the pushing pressure of the propulsion hydraulic cylinder is:

F meter =f0+*pm=f0+mpy=f0+m (0.8952*+2.2888h)

compare the measured results with the calculated results as shown in Figure 1. Curve 1 in the figure is the calculated value, and the point is the measured value. It can be seen from Figure 1 that the thrust force F calculated according to the above formula is greater than the measured thrust force F

2 reasons for the error between the calculated value and the measured value

first, because there is a certain inclination between the excessive edge cutter and the axis of the roadheader, That is, in fact, the pushing pressure of the hydraulic cylinder should be:

f1=f0+ (m1+cosa1+cosa2+... +cosam2) py=f0+ (m1+*m2) py

its difference: *f=f meter -f1=m2 (1-*) py

in the formula, A1 - the sudden destruction of the electronic universal testing machine in the side knife is a small angle between the center line and the axis line of the roadheader

m1 - the number of the front knife blades

m2 - the number of the side knife blades

m - the total number of blades actually installed, M=m1+m2

* -- reduction coefficient caused by the inclination of the transition edge knife to the machine axis

second, due to the rough and uneven face of the tunnel, the hardness value of each blade on the cutter head is not calculated by the following formula during the excavation process: all contact the tunnel face at the same time. In actual work, rocks fall off one by one. At a certain time, only part of the blades work, while only a limited number of blades can be measured during the actual measurement. Figure 2 is the measured radial force curve of a central hob in the measurement

third, due to the interaction between the blade and the blade, when a blade passes through the working face and collapses a large rock, the adjacent blade will not contact the face of the face, thus reducing the number of blades actually contacting the face of the face. Figure 3 shows the measured cutting marks and exfoliated rock blocks on the face of the tunnel. Visible rock blocks with overhead blades and double tool spacing

3 correction of hydraulic cylinder reasoning calculation formula

set the converted blade number that really contacts the face of the tunnel at a certain time as m, Then the pushing pressure of a hydraulic cylinder that goes abroad for short-term training and research is:

f2=f0+*pyn=f0+mpy

*f2=f1-f2={(m1+*m2) -m]py

*f=*f1+*f2= (M-M) py=*mpy

the number of blades that really touch the face of the palm is m=*m. Among them, * is the total conversion coefficient (including the reduction caused by *). The point with great difficulty in Salt Lake expansion in Figure 4 is measured * - variation diagram of H.

it can be seen from the figure:

(1) Conversion coefficient*

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