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.

Bearing removal attention to four basic questions

Bearing removal and installation should be equally careful. Careful not to damage Koyo bearings and various parts, especially the interference fit bearing removal difficult operation. Therefore, at the design stage to take into account in advance for easy removal, according to the need to design the removal tool is also very important. In the demolition, according to the drawings of demolition methods, in order to investigate the bearing with the conditions to obtain the demolition job foolproof.

Removing the interference fit of the outer ring, the circumference of the housing in advance several outer extrusion screw is provided with a screw, the screw tightened equally side, while the removal. These usually cover the screw holes blind plugs, tapered roller bearings, etc. separable bearings, the housing block set shoulders several incisions, the use of pads, with press dismantling, demolition, or gently pounding.

Removal of the inner ring can be used to pull the latest simple mechanical pressure. At this time, pay attention to your inner bear its pullout.

Big ball bearing inner ring removal by hydraulic method. By setting the hydraulic pressure to the shaft hole, to make easy to pull. Large width of the bearing is oil law and drawing fixtures and use, disassembly operations.

NU, NJ type cylindrical roller bearing inner ring disassembly can take advantage of induction heating method. Local heating in a short time, after drawing the inner ring expansion method.

Removal more compact adapter sleeve bearings, fastening the shaft stopper supporting inner ring, the nut back several times, using the pads with a hammer and beat demolished.

Large bearings, the use of hydraulic demolition easier, in the cone axis pressurized oil feed hole, so that the inner expansion, demolition bearing approach. Operation, there is the possibility of bearing sudden prolapse, the best use of the nut block as well as files.

A shaft and bearing selection and control room tolerance bearings pressed into the direction of rotation should be no block flexible. If significant rotation is not flexible, then the shaft size is too large, and forbearance decline. As obvious after entering the "imperfections" in a sense of hand rotation shaft tolerance axial bearings or shaft may be too poor roundness. Therefore, a good shaft and bearing in the control room should be controlled at roundness tolerance, tolerance control only for many domestic manufacturers, no roundness control.

2, the bearing assembly method of the bearing is a precision products, such as improper assembly of the channel, it is easy to damage the bearings, bearing damage. In assembling the bearing should have a dedicated mold, can not hit, into the shaft when the pressure forces can only be a small circle, circle, only by the force loop. Congress requested the pneumatic or hydraulic pressure when using the upper and lower outer mold mounted on a horizontal state, if inclined bearing channel will lead to damage of power, leaving the bearing guide ring bearings.

3, the assembly to prevent foreign bodies mounted on the rotor balancing is done, it is prone to iron homeostasis bearing into the bearing, so it is best to do before loading bearing balance. Some manufacturers in order to facilitate assembly, with some oil or lubricating grease internal coating, carriers bearing assembly is often difficult to control the amount, if the oil or fat in a large indoor bearing, bearing accumulate along the axis, easily enter the bearing rotation. Japan is not the best room bearings coated with oil or grease, such as non-coated bearings, without the accumulation of the control room.

4, anti-rust paint paint rust is characterized in that a sealed multi-motor assembly motor sounds good, but put in the warehouse for some time, the motor becomes a very unusual sound, remove the bearing severe rust. Many manufacturers will be considered before the bearing problem, through our continuous publicity, has now been realized that the main electrical insulating paint factory is the question. The main problem is, insulating paint volatile acid at a certain temperature, humidity, corrosive substances, bearing passage leading to the formation of corrosion damage. The only problem now is to choose a good varnish, after a period of drying air assembly.

Methods to improve the accuracy of precision bearings

In order to improve precision roller bearing with precision the actual installation, you must not make use of the bearing deformation measurement methods and measuring tools, precision bearings and cylindrical bore size of the mating surfaces of the actual precision measurement can be related inner and outer diameters All measurement items to be measured, and the measured data to make a comprehensive analysis of this as far and precision worthy of shaft and housing bore bearing mounting portion size. In actual measurements made with the respective shaft and housing bore size and geometry should be the same with the measuring bearing temperature conditions.
To ensure the effect of a higher actual mating shaft and the bearing bore to match the surface, the roughness should be as small as possible.
In making these measurements, should be cylindrical and the bearing bore, the housing bore and the shaft, and a corresponding surface of the chamfered sides near the assembly, respectively, showing the maximum deviation to make the direction of two marks, so that In actual assembly, the mating alignment of both the maximum deviation of the same position, so that after assembly, the two sides can be partially offset by the deviation.
Directional signs made two aims can compensate for deviations into account, even if both sides supporting each rotation accuracy improved, but also between the two bearing seat hole and both ends of the journal concentricity error partially eliminated. Surface hardening on the mating surfaces to implement measures, such as sandblasting, with a diameter slightly larger than the precision plunger plug holes, once inside, there is help to improve the fitting accuracy.

High-speed precision angular contact ball bearing installation

High-speed precision angular contact ball bearing, mainly used for high-speed rotating occasions lighter loads, requiring high precision bearings, high speed, low vibration and low temperature rise a certain life. Often high-speed spindle support member installed in pairs, is the inner surface grinding spindle speed key component parts.
High-speed precision angular contact ball bearing service life of a great relationship with the installation, you should note the following:
1 bearing installation should be clean, clean room for the bearing to be carefully matching, bearing spacers to go through the grind of maintaining high inner and outer ring spacers under the premise of the spacer should be controlled in parallel 1um the following;
(2) Before installing the bearings should be cleaned, cleaning the inner slope upward, feel should be flexible, no sense of stagnation, dried, placed in a predetermined amount grease, oil mist lubrication should be placed in the case of a small amount of oil mist;
3 bearing installation tool should be used exclusively, even by force, is strictly prohibited beat;
4 bearing deposit should be clean and ventilated, non-corrosive gases, relative humidity less than 65%, long-term storage should be periodically rust.

Angular contact ball bearings operating instructions

1, the operating instructions for the preparation of: according to equipment for the preparation of items that can be processed, which includes operations job preparation and job steps, process characteristics control requirements (processing device parameters, such as grinding diameter, the workpiece and wheel speed , sand turn trimming frequency, slim bearing, eccentricity, etc.; channel coarse and fine, overtime, workpiece speed, beat frequency and angle Whetstone, Whetstone pressure and ultra-precision time and other parameters; tooling adjustment norms, etc.), product characteristics control requirements (process control projects, testing tools, etc.), the main products project failed rework operations guidance.

2, the product process control plan preparation: There are general and specific product model two kinds. Sequential arrangement by a process flow diagram of the process carried out, work number is consistent, some processes can be combined, but the need for notes, such as demagnetization cleaning. Characteristics projects and processes should be the same size cards, it is important also need to specify the process characteristics, such as grinding channel, the wheel speed, workpiece speed, light grinding time, dresser, etc., generally have the book provides guidance on the job, you can indicate references . There are specific types of product specification shall control the planning process and grind super size card processing agreement. Also the measurement technology, measurement sampling samples, control methods and error proofing, response plans and corrective measures, according to the actual production can do and control and to ensure quality content preparation, because of the part of the production control plan requirements must be process control.

3, the product of the preparation process failure modes: first by a process flow diagram and the process of risk assessment, was named high-risk failure analysis to be done.
There are general and specific product model two kinds. Sequential arrangement by a process flow diagram of the process carried out, work number consistent. Included were rated high risk of failure processes may require the presence of all, the possible consequences, which may be the reason of being a means of control methods, and the possibility of them out, and whether measures need to be taken and so on.

Such as grinding end faces potential failure modes and failure reasons: ① width size is too large or too small, mainly related to the grinding time

And stress-related; ② parallelism tolerance, when using the vertical shaft surface grinding machine, its failure causes the wheel spindle is not perpendicular to the magnetic table, magnetic units surface wear, magnetic units magnetic enough, grinding work, "slip", magnetic units surface dirty, dirty work or face burr, magnetic rotary precision is not high, when using double end grinder, the two parallel grinding wheel face is not good, two wheel face serious wear and tear, improper installation exit guide plate, grinding I such as excessive; ③ flatness tolerance, when using the vertical shaft surface grinding machine, its failure causes a workpiece is too thin, heat deformation, wheel too hard, cutting fluid supply, etc., when using the double end grinder, the main export at the guide plate is not properly installed and so on.

Grinding diameter when the potential failure modes and failure reasons: ① aperture is too large, the bearing surface size tolerance, was grinding the workpiece aperture to remain excessive, over automatic feed stroke, etc.; ② tolerance ellipse, oval workpiece support surface too large, reflected in the mill complex on the surface of the workpiece support surface with card injury; ③ cylindricity tolerance, the workpiece spindle axis and the wheel axis is not parallel to the centerline, wheel dressing well, wheel width too wide, vertical reciprocating distance is too short, rough cylinder through the large, rough diameter stay excessive infeed is too fast, too short a time without feeding, wheel too soft; ④ holes face is not perpendicular magnetic clamps enough support position not equal.

Deep groove ball bearings rust knowledge

Deep groove ball bearing division between the rust and rust usually finished rust.
 Workers between the rust belongs antirust processing, usually in 3-30 days. Will generally water-based rust inhibitor can be. The advantage of water-based rust inhibitor is a simple operation and low cost. And rust after degreasing cleaning is not required.

 Finished rust generally refers to the deep groove ball bearing assembly before storage or rust after delivery, usually within a month to 2 years or so. General use apply anti-rust oil or rust VCI paper packaging. VCI antirust paper packaging has the advantage of good rust, free cleaning before assembly, easy to operate, environmentally friendly energy.

 VCI antirust paper will always release a small amount of rust inhibitor (VCI Definition: volatile corrosion inhibitor). In this paper, the package, the package is formed in a protective layer of gas can be reliably suppressed corrosion of deep groove ball bearings. VCI rust-proof paper in direct contact with the bearing and have anti-rust within a certain distance; bearing VCI antirust paper packaging rust, rust-proof up to 3 years; bearing VCI antirust film packaging rust, rust up a years. This is the most used product Harbin HRB, now commonly used in plastic barrels rust processes.

Affect the life of deep groove ball bearing analysis of the factors

Deep groove ball bearing material largely determines the bearing life, once the metallurgical quality bearing steel GCr15 early bearing failure is caused by the most important reason. Technically increased dramatically in the metallurgical, bearing steel and other materials have appeared, has been greatly improved.
 In bearing failure analysis, from raw material bearing failure caused the proportion has also been greatly improved, but is still manufacturing materials main bearing failure, but also with deep groove ball bearing service life considerably relations.

 Bearing complex manufacturing process, to go through several processes before they can get the finished product, including forging, heat treatment, turning and grinding and other processes to complete the technical ability and quality, will affect the bearing life and apply effects, especially heat treatment and grinding process, it is the direct cause of many bearing failures, manufacturers need to be highly valued.
 deep groove ball bearing after installation, in order to check the installation is not correct, you want to run checks. Small machines can be rotated by hand to make sure is not rotate smoothly. Check items mainly due to foreign bodies, indentation caused by dysfunctional, because poor installation, mount poor processing and the emergence of torque instability, because clearance is too small, the installation error, caused by seal friction torque is too large, and so . If no exception, you can begin powering.
 On the shaft and bearing, the bearing requirements in the radial, axial and tangential direction in three directions fix its position. Radial and tangential positioning through the tight fit of the bearing rings mining achieve axial positioning only in a few cases, a tight fit; generally use limit axial parts, such as end caps and rings etc. is limited to the axial position In the clearance range.
     Select match should focus on the following four points:
   (A) the bearing rings and the circumferential surface should be well supported even by force, in order to reduce distortion, and give full play to the bearing capacity.
   (2) In its mating surface of the ferrule can not slide along the tangential direction, otherwise it will damage the mating surfaces.
   (3) the free end of the shaft and the bearing must be capable of bearing adapt to changes in length of the hole, which must have to adapt to the axial position in a range of swimming ability.
   (4) must pay attention to the deep groove ball bearing mounting and dismounting is simple, saving time and labor costs.