Raw material roller press bearing damage cause analysis and maintenance recommendations

In the dry process cement production line process, the raw material has been widely used roller press, and has made considerable economic and social benefits, a significant increase of its energy-saving effect is also recognized by the majority of manufacturers to use. But in the course of its use, the bearing life is short, damage and replacement process cycle is long, costly, labor-intensive, but it restricts the normal operation of the rotary kiln.

My company put into operation by the end of 2012 the two 4500t / d clinker production line, run until June 2003, four sets of Chengdu Lijun Industrial Co., Ltd. manufactured CLF180-120 there have been varying degrees of roller presses the problem of high bearing temperatures, 7 mid-May the 2nd roll maneuver near the gear side roller bearing damage. Total running time of 2041 hours, the service life of less than three months.

First, the device pre-operational status

Roller press run early bearing temperature between 50-60 degrees, there is no abnormal noise, bearing grease used by the U.S. Castrol brand Molub-Alloy 777-2 ES model roller presses grease, the amount of fuel in strict accordance with equipment manufacturers Requests the Executive. Five to six months, there have been several cycles of water blockage, resulting in bearing temperature up to 70 degrees. In mid-June, found that the lower part of the inner bearing oil outlet circulating water discharge phenomenon occurs suspected side of the bearing end cap rupture caused by cooling water, then turn off the inside of the circulating water, the new grease replenishing the oil discharged into the roller press production. In early July, roller presses the bearing temperature has been hovering around 55 degrees to 75 degrees, for various reasons during the roller press is always open to open the stop, there have been more than 24 hours continuously feeding situation. July 10 start, roller press repeatedly appear continuous feeding more than four hours on account of the temperature exceeds 75 degrees to stop jumping. July 12 greaser checking the oil discharge roller press discovered the bearing fragments. Determine the bearing roller press has been damaged. Since the roller press has been put into the roll gap deviation, pressure instability. Deviation due to the roll gap gauge, pressure gauge, the width of the roll gap and other factors frequently exceeds the limit mediation, there have been almost no more than 48 hours continuously feeding situation.

Second, the disintegration of the investigation bearing damage

After the demolition of the roller press gearbox bearing cap open and found that there is a rift bearing outside diameter, a broken ball bearings, inner and outer diameter with five out of crack, the bearing inner and outer raceway badly worn bearing retainer wear . Bearing cap surrounded by circulating water cooling on both sides have two brass compression fracture phenomena, round copper tubes are flattened, leading to fracture, width of about 100mm. Check the other side of the roll maneuver roller bearings, intact, the bearing clearance of 0.75mm, within the normal range.

Third, bearing damage cause analysis and improvement

1 First, bearing life is too short not to troubleshoot and manufacturer of quality bearing assembly itself, but should also work with bearing operating conditions in harsh environments and have a great relationship.

2. Bearing thermal design flaws. Such a large bearing operating process will produce a lot of frictional heat, so that both sides of the bearing cap manufacturer designed circulating path, the heat generated by the bearing grease and the case conduction through the cooling copper tube absorbs heat water circulating outflow apparatus body, lower bearing temperatures. But it cooled copper mounting position is unreasonable, bearing swing too easy to squeeze into the brass, brass deformation caused by blockage, fracture, loss of cooling effect. To avoid copper tube is extruded, only increase the gap between the copper and the bearing, to ensure a greater swing bearing free space, which requires manufacturers to redesign, production bearing cap or another design a cooling device.

3 brass water lead to rupture of the rear bearing lubrication failure, it could be this short bearing life is an important factor. Equipment inspection work found during the inspections bearing lower discharge port has water leakage, immediately made a report, but this is not possible in the cooling copper pipe break after the first time discovered. Since the bearing inner brass cap by squeezing fracture, circulating water entering the bearing, destroyed the environment lubrication, the bearing balls and the raceway serious friction generates a lot of heat, bearing balls and the diameter of each component such damage.

4 brass frequent clogging cooling and design too small, poor cooling effect also affect bearing life. Cooled copper diameter is too small, the circulating water and debris clog adhesion brass scale deposition in the roller press often occurs during operation bearing high temperature, inlet and outlet brass examination revealed multiple blockage, affecting the cooling effect, the final installed at the inlet Y-strainer before easing clogging.

5 roller presses the material into the inadequate control of particle size, diameter 200mm super chunk too, long nip large deviations, corrective frequently lead to bearing overload and shorten the service life. Initial production mining crushing, crushing machine safety door is not well controlled, resulting in more than 150mm above the individual particle size of limestone blocks into the next process, clogging the feed opening roller press, leading to uneven feeding, causing the roll gap large deviations, and even lead roll sewing too large equipment mediation. Granularity than 100mm rigid material frequently enters roller presses, roller presses squeeze in an instant when all the large reaction force bearing on the bearing itself, the life of the bearing caused a fundamental impact. Improved granularity of limestone, sandstone and clay crusher materials and faulty phase continued up to more than two months, no broken, large water through the bypass feed materials into the roller press feeding system, more than 250mm above the chunk size is almost Each class appears stuck roll gap, resulting in the roll gap width gauge mediation. This is the roller press operation there have been no more than six months more than 48 hours continuously feeding the root cause.

6 There is no steady flow positions periodically removed materials, excluding enrichment metal, so that the device frequently overloaded mediation affect bearing life. Material into the roller press is impossible to avoid the presence of metal objects and accumulation roller presses the original width of the roll gap of about 20mm, 70mm roll gap will exceed the overload relief, less than 50mm metal objects will only increase the roll surface wear, greater than 50mm size metal objects or materials into the roller press is too large, it will cause the rollers instantly generate excessive impact force, resulting in the roll gap than 70mm, the pressure exceeds 15MPa, exceeds the bearing load limits, the control system will suddenly roller press release pressure or mediation. Especially metal roller presses will cycle loop in the roller press greatest harm. So they requested that must be periodically clearing, clearing accumulated in the roller press metal objects within the system, reduce or avoid damage to equipment, particularly bearing.

7 hidden when the hydraulic system is now hidden, long-term bias is serious roll gap. As the hydraulic system problems, often lower than the pressure roller presses the side of the working pressure, both sides of the roll gap large deviation hydraulic pump long-term frequent correction, resulting in roller presses the bearing operating conditions poor, heavy load, the service life is reduced.

Fourth, the late running Precautions

Roller press bearing life is short, equipment failure rate is the current cement industry a common problem, through analysis of the above reasons, the production process management is a top priority, as long as control the granularity of the material into the roller press, regularly scheduled clearance, reducing metal roller presses against the probability of overload damage to the bearings, excluding hydraulic system problems, eliminating the long-term bias roll gap phenomenon, problem solving partial cutting, take care of the bearing uniform force. As long as the above points, improving the operating environment of the equipment, the equipment can operate normally, to extend the life of each part, in order to improve the operation rate.