Multi-rope hoist system structure and lubrication

　　  Pulley device is one of the important bearing multi rope friction hoist components, one of its action is bracket elevator wire rope friction hoist vessel turn, used to change the direction of the steel wire rope, which play a guiding role. In recent years, with the continuous development of elevator technology, the manufacturing technology of the wheel has been improved.

　　 The wheel is composed of fixed wheel,  floating wheel, axle and main bearing of both ends, as shown in figure 1. Fixed wheel by flat key and shaft connection, when the elevator running, friction wheel drive the wire rope movement, the friction between wire rope with pulley liner produces fixed wheel rotation, thus promote day shaft rotate at the same time.  When the linear speed of the wire rope is not completely identical, each floating wheel can rotate relative to the shaft of the sky to eliminate the additional torque generated by the linear velocity difference of each wheel.

　　1. Main bearing 2. Fixed wheels 3. Floating wheel 4. Liner 5. Rim 6. Bearing

　　7. 8. Spokes 9. Fixed wheel hubs 10

　　FIG. 1 the structure of the conventional wheel device

　　1 conventional structure

　　The system of the wheel is usually cast welded structure, that is, each wheel is welded by the spokes of the casting flange and the hub and channel steel ( see figure 1 ). The inner hole and the shaft of each swimming wheel are equipped with a two-lobe copper alloy bearing, which is fixed with the end face screw, which makes the axle work simultaneously with the moving wheel. Grease holes are left on each of the wheel hubs so that the grease can be injected into the contact surfaces of shafts and shafts. Because the bearing shell is a vulnerable part, it is convenient for the axle to be replaced at the site, and the space on the side of the wheel is left to move the axles. When the bush is damaged, the retaining ring can be removed first, then the damaged semi - axle is removed from the shaft, and each of the travelling wheels can be carried out in turn during the replacement process.

　　Some elevator manufacturers abroad locate the hub and axle of the floating wheel, as shown in FIG. 2 and 3. In order to facilitate the installation of the key, each wheel body of this connection is divided into two segments.

　　The above three types of structural forms coexist simultaneously in the mine hoist used in our country, which is mainly determined according to the habit structure of the different hoist manufacturers, which belong to the mature structure.

　　2. New structure

　　Rolling bearings are the most widely used parts in mechanical equipment, especially in rotary machines. The new structure of the wheel device, the inner hole of its floating wheel is replaced with a rolling bearing, as shown in  FIG.  4.

　　1. Flat key 2. Fixed wheel 3. Swimming wheel 4. Rolling bearing 5. Spokes

　　6. Fixed wheel hub 7. Axle sleeve 9. Hub end cover

　　FIG. 4 new type of wheel structure

　　Each winding round between the wheel and axle is equipped with two rolling bearing as the support, through the shaft sleeve between the bearing axial positioning, when the linear velocity of the steel rope does not completely phase at the same time, each winding between wheel and shaft through the bearing can be relatively freely and flexibly in the rotation. The oil hole is left on each of the wheel hubs so that the grease can be injected into the bearing regularly. Because of the extremely low speed of bearing, the theory of the bearing can last up to 15 years.

　　At the beginning of the development, the structure is considered to be fixed on the axis of the sky, so that all the wheels are rotated relative to the axis, and the rolling bearing is used to complete the above motion between the hole in the body and the wheel shaft in each wheel. Its advantage is that it saves the main bearing on both ends of the shaft, which greatly reduces the manufacturing cost. The disadvantage is that the operation method requires that the inner ring of the bearing outer ring of each wheel should be at the same speed as the lifting machine, and the inner circle of the inner ring shall not move. Therefore, the service life of the bearing should be higher. Due to the choice of the bearing size by day swimming wheel shaft, wheel hub inner hole and pulley rope spacing, not according to the actual bear the load and the service life of the requirements for a more reasonable choice, makes the service life of the bearing is low, affect the service life of the entire pulley device, therefore, adopt the structure shown in figure 4 is more safe and reasonable.

　　In addition to the requirements of strength and rigidity in structure, the design of the wheel should pay attention to the characteristics of process and installation. The structure need to be aware of is in the process of design and manufacture of rolling bearings inside and outside the circle with day swimming axle and wheel hub of the reasonable coordination, if improper selection with cause cannot be properly installed or can't normal use.

　　3 structure comparison

　　The design method and structure of the wheel can have a great influence on the manufacturing process, and also directly affect the manufacturing cost and performance of the wheel. In table 1, the two structures are analyzed and compared, and their characteristics and shortcomings are pointed out.

　　Table 12 comparison of the structure of the celestial wheel

　　4 the lubrication

　　The wheel installation is mounted on a well rack of several tens of meters high, and though there is a canopy, it can't prevent the wind from blowing in the sun and rain. Because of its harsh environment, lubrication is very important. The lubricating parts of the wheel are bearing bearing and rolling bearing.

　　4.1 rolling bearing lubrication

　　The main bearing on both sides of the wheel is an important part of the wheel device, bearing the dynamic load of the hoist in various operating conditions. The bearing is lubricated regularly, which can prevent the rolling body, the rolling way and the holding frame of direct metal contact, reduce friction, reduce the bearing temperature and prolong the service life.

　　In grease composition, generally consists of three components, namely the base oil (80% ~ 90%), and formed a fixed the grease thickener (10% ~ 20%), and to improve the durability of various additives [4] or lubrication performance. The performance of the base oil directly affects the performance of all aspects of the grease. The thickener can thicken the base oil to the semi-solid, which, like the base oil, determines the nature of the grease.

　　It is very important to choose the type and number of grease. When choosing grease, according to the working conditions and environmental conditions of the bearing. When working at high temperature, choose the anti-oxidative ability good, drop point higher grease. When working at low temperature, you should choose grease that has small viscosity and low viscosity. For the equipment that changes in the working environment, the two should be considered, such as the choice of synthetic fat.

　　2 lithium base grease and complex lithium base grease is the most commonly used grease and complex lithium base grease than lithium base grease performance is better, it has excellent mechanical stability, bearing leakage quantity is little, and it has excellent water resistance, rust and oxidation stability. Compound lithium base grease is one of the main development of grease products in China. And the current widely used 2 complex lithium grease has good lubrication, the high and low temperature performance is better, not only has better low temperature pumping sexual (winter start in - 30 ℃); And has higher dropping point, the drop point is 283 ℃, 100 ℃ higher than that of lithium grease drop point of left and right sides, using temperature is 160 ℃. Summer anti-dumping and adhesion force can keep the bearings running at low temperature, and can extend the grease and grease cycle. When selecting bearing grease, it is recommended that the base oil viscosity is better between 320 ~ 500 CST.

　　For conditional mines, especially the users imported bearing, mobil producing synthetic compound lithium base grease force rich Mobilith SHC " series is a kind of very good choice, such as Mobilith SHC " 460, in many mines using in good condition.

　　Grease should be replenished regularly during use. The complement of the grease cycle depends on many factors, including bearing type and size, speed, working temperature, the type of grease, and the work environment and the inner cavity of the bearing space, so added interval usually by using unit depending on the specific situation. In addition, the inner cavity space of the bearing seat is not too much grease, which should be one/two to one third. Otherwise, it will increase the resistance and cause the bearing temperature to rise.

　　When adding grease, it is necessary to consider whether the newly added grease is compatible with the original grease in the bearing. If the incompatible grease is mixed together, the consistency will definitely change, and the grease can be lost in large quantities, resulting in poor lubrication. Therefore, if the newly added grease is incompatible with the original, it should be removed from the original and added to the new grease, instead of adding it to the usual method.

　　With the same grease base oil, thickener and similar general can mix and there would be no bad reaction, such as lithium mineral oil grease usually can be mixed with another kind of lithium mineral oil grease.

　　It should also be noted that the grease used must be kept clean to avoid dust and moisture intrusion, and when grease is added, impurities can not be carried into the bearing and bearing box. The dust particles and dust in the lubricant can significantly reduce the life of the bearing and increase the wear and noise of the bearing.

　　Many users are common pitfalls: using low viscosity mineral base oil of ordinary 2 lithium base grease in order to reduce costs, low viscosity of grease can't form a thick oil film, bearing wear caused by acceleration, summer grease flowing, throw, cause bearing high temperature, shorten the bearing life. Choosing high quality grease can help prolong the replenishment cycle of grease and prolong the service life of the bearing. Especially for installation in the open air on the derrick pulley, depending on the region of use, its temperature may range in - 30 ~ + 50 ℃.

　　4.2 bearing lubrication

　　As the main bearing capacity of the wheel, the lubrication condition directly determines its service life. When the shaft lubrication is bad, the ends of the end of the travelling wheel and the shaft are cut off, causing the axial movement of the axles and causing the abnormal sound. In addition, the oil will cause wear when the bearing oil is short, and the drying of the shaft will cause the burning of the tile, resulting in the overall failure of the wheel. Good lubrication can keep the oil film state between the shaft and the shaft of the shaft, prevent and reduce the friction surface of the shaft, and prolong its service life. Therefore, it is very important to add grease regularly. The recommended filling period is 3 ~ 7 days. Because of the moderate price of lithium base lipids, it can be used to use lithium base 2 or 3 .

　　5 conclusion

　　The paper analyzes the structure and lubrication of the multi-rope friction hoist with the purpose of improving the service life of the wheel device. The rapid development of science and technology has promoted the improvement of modern design and manufacturing capacity, and fierce market competition is becoming more and more dependent on the competition of technology. As the elevator market internationalization, step by step for the pulley device performance requirements also more and more high, this will drive hoist the designers of continuous innovation, to produce more excellent high efficiency, energy saving, easy to use maintenance pulley device.