Determination of mining equipment motion resistance

The article presents the experimental measurement of the mining equipment motion resistance in the Mining Plant 1, the Lazy mine location district. The procedure of the experimental tests was as follows, one of the transport vessels was fitted with a weight of a known weight. The mining cage was loaded with the weight and pulled up in the traffic pit to the required depth, then the mining equipment was released and, using the IRC rotation speed sensor attached to the rope drum shaft, the travelled trajectory and the instantaneous mining cage speed were recorded with an indirect method. Upon reaching the speed of the transport vessels, a maximum of 3.15 m/s, the vessels were equipped with the mining equipment brakes and the transport vessels were slowed down to zero speed. From the recorded data in the PC memory, ie initial positions of both transport vessels, travelled trajectory and instantaneous speed values, the values were consequently calculated and added to the stated tables.


Introduction
In a deep mine in the Karviná district, located in the southern part of the Upper Silesian coal basin of the OKD, a.s., in the Mining Plant 1, the Lazy mine location, measurement of motion resistance of the mining equipment No. 1 in the down-cast air shaft No. 5 was carried out with the participation of the INCO engineering s.r.o.

The course of experimental tests
Experimental measurement of the mining equipment motion resistance was carried out under operating conditions, when all the safety features of the winder were ecommissioned. Mining vessels were then set up by a machinist in the down-cast air shaft in a desired position to provide sufficient weight predominance in the branch, which, after releasing the mining equipment, overcomes the static motion resistances and puts the transport vessels in motion. In order to obtain the required motion resistance values of the mining equipment No. 1 in the down-cast air shaft No. 5, the data of actual positions of the two transport vessels in the traffic pit were used and were substracted from the console display in the engine room, see Fig.3.
The measurements were carried out under four input conditions, when the transport vessel was fitted with a weight of 0, 1000, 2000 and 3000 kg.
The procedure of the experimental tests was as follows -one of the transport vessels was fitted with a weight of a known weight mz [kg]. The mining cage was loaded with the weight and pulled up in the traffic pit to the required depth, then the mining equipment was released and, using the IRC rotation speed sensor attached to the rope drum shaft, see Fig.  4, the travelled trajectory and the instantaneous mining cage speed were recorded with an indirect method. Upon reaching the speed of the transport vessels, a maximum of 3.15 m/s, the vessels were equipped with the mining equipment brakes and the transport vessels were slowed down to zero speed. From the recorded data in the PC memory, ie initial positions of both transport vessels, travelled trajectory and instantaneous speed values, the values were consequently calculated and added to the stated tables. In order to obtain the values of the speed of the motion and the travelled trajectory of the transport vessels in the transport pit, from which it was subsequently possible to calculate the acceleration of the transport vessels, a measuring sensor, see Fig. 4, was used. It sensed the speed of the mining equipment shaft and via the software, see Fig. 5, it graphically depicted the instantaneous position, speed and acceleration of the transport vessels, see Fig.6. The data scanned from the measuring sensor of the partial measuring was saved in the memory of the portable computer as a data file for subsequent processing.

Evaluation of experimental tests
The first experiment was based on a number of operational measurements, the results of which were to enable the maximum value of static resistance to be counted against the rotation of the rotating parts of the mining equipment [1], [3]. The experiment was carried out as follows: a weight of a known weight m z = [kg] was put into one of the mining cages. The loaded mining cage was lowered to the proper depth of the down-cast air shaft, where it was brought to a quiescent condition by the equipment of the winder brake. At the moment when all the sliding and rotating parts of the mining equipment were in a non-moving state, the brake of the winder was released, and it was observed whether the mining cage was starting. In Table 1 -operating condition where the transport vessels were not fitted with any weight, ie. m z = 0 kg, the values of the initial positions of the transport vessels H o [m] and H k [m] are provided in the first and second column. The friction coefficient f č [-] is proportional to the vertical force (ie the weight of the rope drum) and generally indicates which force should be used to move one body against the other one. Depending on whether the body moves from a rest position or only stays in motion, it is possible to distinguish between static friction coefficients and sliding friction [4], [5].
For sliding bearings of the rope drum, it is assumed that the friction coefficient of the contact surfaces at acceleration (gap semi-dry friction) is f č = 0.1 to 0.25 at rpm above 0.5 rps, and f č = 0.01 to 0.001.
From the relation (1), it is possible to determine the own weight of the rotating parts of the winder, including the rope drum m rb [kg], see the relation (5).
According to the Table 1, it is possible to define that the amount of the rope drum rotation resistance O p [N] increases depending on the size of the difference in the H [m] position of transport vessels in the traffic pit. At some point, when the rope drum rotation resistance O p [N] is exceeded, ie. the frictional resistance of the sliding bearings of the rope drum, the traffic vessels move in motion due to the prevalence of load in the given branch of the mining equipment [6].
Comparing the Table 1 values on the positions of the two transport vessels for measuring no. P (where the friction resistance of the rope drum sliding bearings have not been overcome by the weight predominance) with the position values of the two transport vessels in the Table 3 for measuring no. L1 (where the friction resistance of the rope drum sliding bearings have already been overcome by the weight predominance), it is possible to conclude that the motion resistance is O p = 8320.66 N. Using Fig. 8, the relation (6) From the drawing documentation of the mining equipment in question, it was found out that the actual weight of the winder shaft is m h = 8600 kg, the weight of both drums m 2B = 29560 kg and the weight of the rotor of the driving engine m rm = 7000 kg. Actual weight m s [kg] see (8).  In Table 2, there are values for the operating condition, when the transport vessels were fitted with a weight, ie. m z = 1000 kg and 3000 kg.
In Table 3 Table 3). Times t 1 [s] and times t 2 [s] can also be subtracted from graphical records of the partial experimental measuring, see Figure 6.
For the experimentally obtained data saved in the PC, ie. the speed of the winder shaft in the course of time, and from the graphical records, see Fig. 6, it was possible to determine the total motion resistance of the O pa [N] and O pb [N] of the rotating parts of the two-drum winder, see Table 3.
From the data files, see Fig. 9, the value of the travelled trajectory h [m] by the mining vessel at the time tj = t 2 -t 1 [s] (see the fourth column in Table 3) was subtracted at the time t 2 [m] and the maximum speed achieved in [m/s] (see the fifth column in Table 3). The travelled trajectory h [m] and the maximum speed achieved in [m/s] can also be subtracted from the graphical reports of the partial experimental measuring, see Fig. 6.
where O pa [N] is the total motion resistance to movement. In case of b), at the moment of starting the left mining vessel, it is possible to determine a balance equation of occurring load in the two branches of the mining equipment (11), from which the value of the total motion resistance Op [N] can be determined by a modification, see the relation (12).
Assuming that both mining vessels are of the same weight, ie. m o = m k [kg], it is possible to determine, for the known values (see Table 3  Assuming that the right mining vessel has a weight, i.e., m k = m o + m x [kg], where the weight predominance over the weight of the left transport vessel is determined as m x = 450 kg, it is possible, for the known values (see Table 3  The total rope drum rotation resistance O p [N] as the friction resistance in the sliding bearing of the rope drum shaft was determined in the Table 1 (for measuring No. L) at the value T = O p = 8320,66 N, which is one of the components of the static resistance F s [N].
If the instantaneous driving force F [N] putting the transport vessels of the mining device in motion is given by the value stated in relation (30) and the static resistance F s [N], the value O po = 8320,66 N, the relation (16) can be modified into the form of (17), and placing a component of the inertial force of the sliding masses F dp [N] into it, expressed according to the relation (18). s d dp dr dp dp 2 2 J dv J dv F -F = (F = F + F ) = F + . 8564,62 -8320,66 = F + . [ Where: The total weight of the sliding masses m p [kg] given in the relations (15) to (17) can be expressed according to the relation (19) using the relations (1)   For known values (see Table 3  According to the materials provided from the production documentation of the winder, it is known that the actual value of inertia moment of the two rope drums, including the shaft of the mining equipment, is J bs = 71. 2

Conclusion
The report describes a unique experimental measuring, which was carried out on the mining equipment No. 1 of the down-cast air shaft No. 5 of the Mining Plant 1, the Lazy Mine location, which is equipped with a two-drum winder. The uniqueness of the measurement carried out was that during the experiment, the drive engine was decommissioned and all safety features of the mining equipment were blocked in order to allow the movement of the mining cages through the pit only by its own weight when the static resistances of the mining equipment were overcome.
From the deducted values, from the control panel in the engine room of the mining equipment, the initial positions of the mining vessels, the known weight of the two mining cages and the weight of the mining rope, the maximum static resistance was determined, which, in the normal operation of the mining equipment, exceeds the drive engine as one of the motion resistance components. The static resistance determined by this experiment is determined only as the rolling resistance of the sliding bearings of the rope drum shaft, and the resistance of the roller bearings of the ropes, where both ropes are guided into the pit, has not been taken into account.
The second part of the experimental measurement, based on the values obtained by measuring of the travelled trajectory and the instantaneous speed of the mining cage and the known initial positions of the mining vessels, was intended to determine the dynamic resistance that occurs during the start of the mining equipment engine.
The total motion resistance determined by calculation does not take into account other resistances normally encountered during the operation of the mining equipment, such as air resistance, friction resistance (sliding or rolling) of the mining crane against the guide [9][10].