Under normal circumstances, the development of open pit mine projects must comply with certain procedures. For a step, the development of mining engineering, first of all to dig into the ditch, as shown in the ABCD part of Figure 3-5. Then, based on this, the trench EFGH is opened and the transportation route is laid. After the trench is drilled to a certain length or the full length of the working line, the working surface FHIJ is placed on one side or both sides of the trench for pushing (mining or stripping). For the upper and lower steps, when the previous step pushing work is carried out to a certain position (advance B distance in Figure 3-6), the next step of trenching and pushing can be carried out, so the mine works from the first One step is extended to the second step (AECD). In the future, the extension of each step will be carried out according to this procedure until it is extended to the final mining depth of the open pit. It can be seen from the construction form that the development of the open pit mine project is a process of continuous trenching and pushing up from top to bottom in a certain level of open-pit mining. In the same mining level, the trenches are digging into the ditch, and the trenches and pushes are opened, and Xi'an City is in turn; then some of the works can be paralleled and coincident in time; the direction of the working line is continuously pushed from one side to the other. Until the final exploitation of the realm. See the upper and lower mining levels, the upper horizontal push and the lower horizontal trenching work are kept at the same time. The contour of the stope is gradually small to large, from shallow to deep, until the end of mining in the final boundary of the open pit mine (Figure 3-7). The development of the organization of open-pit mine projects is to make the parallel operation time as long as possible under the conditions allowed to improve the speed of mine engineering. The so-called aligning bearing is that the raceway raceway is spherical, and it can adapt to the angular displacement between the two raceways, which is mainly supported by radial load, and can also bear a small number of two-way axial loads.
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Characteristics of core bearing
It is mainly subjected to radial load, and it can also bear a small amount of bidirectional axial load.
The center ball bearing is the inner ring of the two raceways and the outer ring of the raceway for the spherical surface, and the ball bearing is assembled with a ball shaped roller. It can bear a large radial load and also bear a certain axial load, as shown in Figure 1. The outer raceway of this kind of bearing is spherical, so it has the performance of adjusting center.
The main features of the ball bearing are as follows:
(1) the outer race raceway of the ball aligning ball bearing is a part of the sphere. The center of curvature is on the bearing axis. Therefore, the bearing has the function of adjusting the center, and it can be automatically adjusted when the shaft and shell appear flexure, and does not increase the bearing burden.
(2) an appropriate amount of axial load that can bear radial load and two directions. But it can't bear the torque load.
This kind of bearing has smaller contact angle, almost no contact angle under axial load, small axial load capacity, large radial load capacity, and suitable for heavy load and impact load.
(3) the double row center ball bearing with tightened and locking nuts can be installed at any position on the optical axis and does not need to be positioned on the shoulder.
Spherical Roller Bearing is in the two groove of the inner ring and outer ring raceways between Spherical Bearing assembly, a drum shaped roller, as shown in figure 3. Spherical Roller Bearing with two rollers, mainly bear radial load, also can withstand any direction of the amount of axial load; radial load capacity is very high, especially suitable for radial heavy loads or vibration, but unable to bear pure axial load.
The main characteristics of the spherical roller bearing:
(1) bearing with self-aligning ball like outer ring spherical roller bearing raceway is a part of spherical surface, the curvature center on the bearing axis, the bearing outer ring raceway is spherical shape, so its self-aligning performance is good, can compensate concentricity error, thus can realize the automatic aligning.
(2) in the section perpendicular to the rolling direction, the roller busbar is a curve, which fits well with the inside and outside raceway. The roller and raceway are linear contacts, which can bear radial load and axial load, and has good impact resistance.
(3) roller and roller bearing raceway match well, and are therefore relatively serious curve generatrix, sliding, friction than cylindrical roller bearings, spherical roller bearings are allowed so low working speed.
(4) the heart fades with a normal roller bearing non symmetrical roller, it will generate an axial force, roller by the force and the center fixed flange contact, spherical roller bearing symmetrical roller, it can move along the axial direction using the middle movable baffle ring, so no longer block roller center the edge of the constraints, and saves the recess of the inner raceway, the roller can be used longer, so as to improve the bearing capacity.
(5) single row self-aligning roller bearing contact angle is 0. Under axial load, the contact angle did not change significantly, the axial load will be very small contact forces generated great between roller and raceway, so when the axial load is greater than the radial load, the loads of single row spherical roller bearing can bear radial and axial.
(6) bearing with self-aligning ball like set with tight double row spherical roller bearing can be installed in any position on the optical axis, do not need to process the positioning shaft shoulder.
Chapter III Basic Concepts of Open-pit Mining - Section 4 Open-pit Mine Engineering Development Procedures
As previously indicated, the recovery of ore and rock from open pits is accomplished by a process that is collectively referred to as open pit mining. The open pit mining project is divided into stripping engineering and mining engineering according to the object; it can be divided into trenching engineering and pushing engineering according to the construction form.