Vibrating screen can not start, bearing overheating and other 7 types of failure, detailed explanation of the causes and solutions

In the mining, as well as mineral processing, coal processing, building materials, chemical industry and other sectors, vibrating screening equipment belongs to the important equipment that must be available, and the performance of its advantages and disadvantages will have a direct impact on the production capacity and technical and economic indicators. As far as the vibrating screen is concerned, the same failure may be triggered by different reasons, and the corresponding solutions may be different. Therefore, in production practice, it is extremely necessary to master the diagnosis and solution of some common vibrating screen failures. This article will share some of the faults and solutions that are often encountered in the production process of vibrating screen. The vibration source of the screen body is the vibration exciter, the amplitude can be adjusted by virtue of the counterweight, the exciter starts to operate, relying on the centrifugal force generated by the eccentric mass rotation as the excitation force, when the biaxial vibration exciter synchronous rotation, prompting the screen box to carry out the reciprocating linear vibration, the material is screened through the screen surface aperture to implement screening, and ultimately to achieve the final product of the ore screening work. Shaker failure usually exists in the following situations: First, heavy load state start, due to production or other equipment failure resulting in a sudden shutdown, resulting in the screen box filled with mineral material, if the shaker is started again under heavy load, it is very easy to cause damage to the universal coupling of the shaker and other parts. Therefore, the vibrating screen should be prevented from running again under heavy load. Damage to the vibration damping system, such as the loss of effectiveness of the vibration damping spring or excessive accumulation of materials under the screen, will cause the vibration damping system to become uncoordinated, resulting in damage to the shaker, we should regularly check the vibration damping spring, for the failure of the deformation of the spring needs to be replaced in a timely manner, try to replace all the vibration damping springs at the same time, and make sure that the stiffness of each group of springs before and after the replacement is the same.3, when the maintenance, if in the maintenance and installation process, it is very easy to cause damage to the universal coupling and other components of the vibrating screen. If the shaker gap is not properly adjusted in the maintenance and installation process, it will cause the shaker and the motor, the axial radial joints between the universal coupling, and the relative position of the shaker eccentric block and so on, resulting in excessive vibration of the shaker, resulting in high temperatures, which seriously affects the normal work of the vibrating screen. Installation and operation, the two motors must be selected as far as possible, the same damping, downtime the same type of motor, so as to ensure that the two motors synchronous operation of rotation; shaker in the installation, be sure to ensure that the two motors running in the opposite direction; motor and shaker must be in the same vertical plane and so on, especially in the vibration exciter maintenance work, the vibration exciter is a pair of simultaneously put into use. For a pair of shakers in use at the same time, the quality of the eccentric wheels must be the same. When editing and disassembling the shaker, there are a few points to note: the shaker should be disassembled and assembled in a clean area, all parts should be cleaned up before assembly, burrs should be removed, and the inner and outer rings of the bearings should not be directly tapped, and all assembly surfaces should be coated with lubricating oil such as lithium grease prior to assembly, and the seals should be carefully inspected, and if they are aging or damaged, they should be replaced in a timely manner, and the appropriate amount of lubricating oil should be installed to comply with the specified requirements, like lithium grease, etc., and the Y-type seals should be assembled with the end rings. Y-type sealing ring should pay attention to the end face inward, all bolts are fastened according to the provisions of the installation of the initial period every one or two days fastening, more than three consecutive times, and then every two days to check. Vibrating screen vibration crack failure, in its working process, the screen frame will tremble, and then sprout bending fatigue, so it is easy to cause the screen frame, side plate and other local deformation or vibration crack situation. Among them, the vibrating screen in the use of the stage of vibration cracking failure mainly covers the following reasons: First, the vibration damping spring failure, after a long period of time after the use of the spring, due to the aging of the rubber or long-term force, making the spring to produce permanent deformation, and ultimately lead to the failure of the spring, resulting in the vibrating screen screen body of the four groups of vibration damping spring seat pivot point height difference, which leads to the amplitude of the vibrating screen is not the same in all parts of the vibrating screen, resulting in the vibration crack or connection parts. Vibrating screen connecting parts vibration cracking or connecting parts weld cracking. Should regularly check the vibration damping spring, and select the spring material, usually choose, after heat treatment its hardness to reach HRC45 - 50, 2, the exciter eccentric wheel quality deviation problem Exciter, above the role of the eccentric wheel is to let the vibrating screen vibration, the size of its quality will be directly on the vibrating screen amplitude value caused by the impact of the eccentric wheel quality deviation, during the operation of the vibration generated by the vibration screen, the vibration of the vibrating screen amplitude is not the same. The quality deviation of the eccentric wheel, the vibration force generated during operation will lead to dispersion phenomenon, which is reflected in the vibrating screen body, showing inconsistent amplitude in various parts, and ultimately triggering the vibrating screen connecting parts vibration cracks or connectors welded joints to produce cracks. When the installation of the shaker, with universal coupling connected to the shaker, by the transmission shaft torque, there will be such a situation: 3, the eccentric wheel re-plumbing and natural re-plumbing line does not coincide, resulting in the rotation of the eccentric wheel is not synchronised, which makes the vibrating screen amplitude of each part is not consistent, and ultimately lead to the vibrating screen vibration cracks in the connection parts or connection welding joints cracking. Moreover, 4, the shaker eccentric wheel counterweight is not appropriate, will also make the vibrating screen amplitude imbalance, if the counterweight block increase too much, will make the amplitude exceed the permissible value, all of these will cause the vibrating screen connecting parts of the vibration cracks or connectors welded joints cracking. 5, the screen plate is thin resulting in the sieve frame breakage of the case may exist, and the best way to solve this problem is to moderate thickening of the side plate, or in the vicinity of the side plate of the vibrator to locally add the side plate. The best way to solve this problem is to moderately thicken the side plate, or in the vicinity of the shaker side plate partially add a plate to enhance the rigidity of the entire sieve body, so that the sieve frame will not be prone to tremor and fracture. When welding, the weld should follow the longitudinal direction of the screen frame, absolutely no horizontal weld, otherwise the tube beam is more likely to break from the horizontal weld. Sieve frame fracture or pipe beam fracture according to the principle of fracture mechanics, sieve frame trembling caused by bending fatigue, and then easy to fracture. If the screen frame breaks, then there is a high probability that the screen plate is too thin. The best way to solve this problem is to moderately thicken the side plate, or add additional plates to the side plate near the shaker to enhance the rigidity of the entire screen body. For the pipe beam breakage there are generally the following situations: 1, the most common cause is due to the pipe beam wall is too thin, the solution is to replace the pipe beam with the same type of thick-walled pipe or use a larger type of pipe beam, but also should not be too large, too thick pipe beam mileage. 2, dewatering, desiccating sieve screen in the connection of the various panels, there must be longitudinal and transverse pressure strip, this is to avoid water, the screen frame is not easy to fracture. This is to avoid water leaking down from the gap of the screen, which may cause the breakage of the pipe beam at the scouring place.3, the wider the screen is, the easier it is for the pipe beam to break, according to the experience accumulated from on-site use and referring to the German manufacturing technology, when the screen width is more than 3m, it is most suitable to adopt double channel, which means the screen has 3 side plates, so that it can effectively prevent the occurrence of the breakage of the beam.4, if the pipe beam does not break very much, it is not suitable to use too big and too thick pipe beam, so it is not suitable to use too big and too thick pipe beam. If the degree of pipe beam breakage is not very serious, in order not to let the production be affected, the pipe beam can be welded in order to continue to use. When welding, the weld should follow the longitudinal direction of the pipe beam, absolutely prohibit transverse weld, otherwise the pipe beam will be more likely to break from the transverse weld place. Bearing overheating, under normal circumstances, the normal temperature of the bearing should be maintained at 35 to 60 ℃, if the bearing temperature is high during the use of the bearing, there may be the following reasons: 1, the bearing radial clearance is too small, because the vibrating screen bearing above the load is relatively large, high frequency, and the load has been in a state of fluctuation, so the bearings must be used in large clearance. If the use of ordinary clearance bearings, it is necessary to grind the outer ring of the bearing again, so that it becomes a large clearance. The bearing gland is too tight, and there must be a certain clearance between the gland and the outer ring of the bearing to ensure normal heat dissipation and a certain amount of axial runout of the bearing. The gap can be used between the end cap and bearing housing gasket to be adjusted. Bearing lubrication is not good, bearing oil or bearing oil is contaminated, will lead to bearing overheating, at this time to the bearing oil, cleaning, replacement of oil and seals, check the quality of oil and oil injection, in addition to perhaps bearing wear or bearing quality problems. If the sound is abnormal or the noise is big, then the screen box or side plate is cracked, you need to check the screen frame and side plate for signs of cracking, and the cracked parts should be welded or replaced in time. If the bearings are damaged, the bearings should be regularly oil lubrication operation, and should be replaced in a timely manner to the bad bearings. 3, the screen box side panels, rear end plates and other plate structure of the sound, because the screen box side panels, rear end plates and other plate structure are formed by the thin plate through welding or riveting, these large areas of the thin plate in the vibration force under the action of the radiation will radiate a relatively strong noise, the plate radiation noise size and the plate vibration speed is proportional to the square of the plate surface. The size of the plate radiation noise and the square of the plate vibration speed is proportional to the relationship, so the plate can be taken to impose constraints on the damping material to achieve the goal of noise reduction. 4, the screen is not pressed or some of the bolts appear loose, in view of the prolonged vibration, the screen or bolts will naturally loosened, should be frequently inspected and tighten the bolts of each part of the 5, the spring appears to be damaged because of the long term use of spring steel changes, become longer or shorter, and the spring will be damaged. 5, the spring is damaged, because of long-term use of the spring steel changes, the length is not the same, and then collision with the base and the screen box, in this case should be timely to replace the spring, or change to rubber springs. 6, the exciter bearings due to their own vibration and sound, to add a soft acoustic enclosure on the outside of the vibration exciter. 7, the material collision with the chute, the reason is that vibration sieve chutes are welded by the steel plate, the material in the chute collision and friction will also generate a large noise. Collision and friction in the chute will also produce greater noise, so in the feed and discharge chute on the inner wall of the rubber liner, or made into a box, which can reduce the chute noise. There is such a situation, that is, can not start, or the amplitude is less than 1, this time if the motor or electrical components are damaged, first of all, check the motor, if the motor is damaged, then you need to replace the motor; secondly, check the electrical components in the control line, if the electrical components are damaged, then you need to replace the electrical components. There is also a situation, that is, the voltage is insufficient, this time to test the power supply voltage, and then change the power supply. In addition, if the vibrator fails, firstly, we should check the viscosity of the grease in the vibrator, and then add the appropriate grease, and secondly, we should check whether there is any failure of the vibrator, and if there is any failure, then we should check and replace the vibrator. 4, the screen surface of the vibrating screen is too much material there, and the remaining materials in the funnel of the under-screen material or the material is too much, which leads to the increase of the load of the vibrating screen when it is starting up, so we should clean up the screen surface and the funnel of under-screen material in a timely and thorough way! It is necessary to timely and thoroughly clean up the remaining materials or accumulated materials on the screen surface and in the sieve funnel. If there is a screen machine swing phenomenon, the most likely reason is that the spring height difference or stiffness difference is relatively large, this time you need to measure the spring height and stiffness, when necessary, replace the spring. Therefore, in production, the vibrating screen vibration damping buffer spring, to focus on maintenance. To regularly clean the dust material around the spring, so as to maintain a good buffer effect. Also on the vibrating screen body and shell between the four buffer damping block top wire to be adjusted, so that can minimise the screen machine swing condition. (Run the world's great dragon dragon dragon out of the East Tengda world dragon three types of spherical roller bearings Liu Xingbang C E MB MA) why your bearing is not durable and easy to aging it? Please pay attention to the following points, bearings as an indispensable key component of mining machinery, the duration of its use by more and more attention. However, in daily use, we can clearly perceive that, under the same working conditions, the appearance of the same type of bearing, the actual life expectancy is very different. What is this all about? Pay attention to the following points! 01 with too close, when the inner ring of the bearing is forced into the journal, the degree of light will lead to the bottom of the raceway has a serious wear ring traces appear, the degree of heavier in the slideway, the outer ring and the ball will appear on the crack or peeling phenomenon. The reason is that the clearance between the ball and the slideway is squeezed too small, torque increases, friction increases, bearing temperature is too high, resulting in bearing wear and fatigue and failure. Prevention is to restore the radial clearance of the bearing, reduce the amount of interference. Method one is the visual method, when the motor end cap bearing room mounted bearing, can be used to turn the end cap, if the bearing rotates freely, flexible, and no vibration as well as up and down shaking phenomenon, then it will be regarded as qualified. The second method is the plug ruler inspection method: the motor end cover with bearings assembled on the seat stop, the use of 0.03mm thick plug ruler to check the radial clearance of the bearing week, if the maximum clearance position is just above the centre (motor horizontal installation), it shows that the assembly is correct, reliable, and vice versa, belongs to the installation is bad. At this point should be appropriate to adjust the position of the end cap, re-assembly, until qualified. Edit 02, the lack of lubrication is due to a serious shortage of grease or grease aging due to drying out. Given that the motor to run at high speeds to cause friction and thus generate heat, which leads to excessive rise in bearing temperature and oxidation changes in colour, showing the condition of the bearings of the ball, cage, inner ring, and its journal and other parts of the change to brown or blue. The way to prevent this is to determine the time to replenish and replace the grease based on the four factors of the motor's operating hours, ambient temperature, load conditions, and the quality of the grease. Under normal circumstances, the motor running up to 6000 ~ should be supplemented with grease 1 time; running up to 10000 ~ should be replaced with grease 1 time, the amount of replacement grease for the bearing chamber volume of 1/2 ~ 2/3, and should be used in good quality lithium grease. If the installation is not centred, then there will be bead marks on the slideway of the bearing, uneven wear marks on the balls, and also produce skew, with a ruler to check the clearance on both sides of the bearing will be unequal, and the difference is large. The reason may be that the outer ring of the bearing is directly hit with an iron hammer, the transmission belt is too tight, the gear bite is too tight, resulting in the centre line of the active and passive wheels are not parallel. When the deflection is greater than 1/1000, it will cause the bearing running temperature is too high, the slideway and the ball is seriously worn, the rotating shaft is bent, the end cover bolt compression surface and the bolt axis is not perpendicular. The correct installation method is to use the steel pipe sleeve for installation, the end surface of the sleeve should be smooth and flat, and almost equal to the thickness of the inner ring of the bearing, and press the bearing on the correct position of the clean journal. The bearing should be pressed into the correct position on the clean journal. The pressure should be even and never too strong. After that, according to the different speed of the motor to check the permissible value of radial deflection of the shaft end. 04 strong vibration, when the generator core failure, it will cause the bearing to produce strong vibration. The reason is that the core is deformed by heat; the motor bearings are aged; the rotating shaft is bent and deformed to a large extent; the bolts tightened at the end cap stops are loosened because of vibration; the foundation is not solid, thus causing the bearings to vibrate. Preventive measures include: turning the core to a smaller size, soaking the surface of the silicon steel sheet and the gaps between them with silicone varnish 1052; replacing the bearings with new ones of the same type; withdrawing the rotor core in order to straighten the bent portion of the rotor shaft; adopting the 180° symmetry method; tightening the bolts on the end cap stops; reinforcing the foundation; and tightening the ground bolts. 05 Material fatigue occurs if the metal material In case of fatigue of metal materials, irregular fragments from bearing raceways and ball surfaces, if mixed in the grease, will result in higher operating noise, sliding of balls, increase of radial clearance of bearings, and increase of the permissible radial deflection of the shaft end by 2 to 3 times. The load of the motor, will affect the degree of bearing fatigue, speed will also affect the air gap also has an impact, end cap type also plays a role in which the toughness of the material will have a decisive role, the quality of the grease will affect the grease loading will affect the degree of bearing fatigue. Then, the prevention method is based on the motor operation record, when the light load working current is in the rated value of 60% above, running to 2000 ~, medium load working current is in the rated value of 60% ~ 80% running to 15000 ~, heavy load working current is in the rated value of 80% ~ 100% running to 10000 ~ after the Should consider the normal fatigue of the bearing material, to replace the same type of new bearings. 06 contamination corrosion at this time, the raceway and the surface of the ball there, appeared red, brown spot corrosion, and the new bearings, compared to the sound, the work of the noise increased. The reason lies in the assembly place is not clean, if there is moisture, acid, alkali and toxic gases; tools and hands are contaminated; the use of poor quality grease. Preventive measures is to assemble bearings to keep the environment, tools and hand clean; cleaning bearings to do thoroughly; replacement of high-quality lithium-based grease.