causes and solutions of severe vibration of ball mill pinion - fodamon machinery
In the daily production of theball mill, there will always be some sudden failures, such as severe vibration of the ball mill gear, cracking of the large gear ring of the ball mill, or the sudden increase in the temperature of the ball mill bearing. accident. Fodamon engineers shares the reasons and solutions of the severe vibration of the ball mill pinion.
The normal operation of the ball mill uses the motor to drive the ball mill to perform rotation operation. The motor drives the ball mill to directly connect the pinion through the elastic pin coupling and drive the big gear ring to realize the operation of the ball mill. In the process of operation, if the pinion and its base are found to vibrate violently, it is mainly because the distance between the pinion and the anchor bolt is far, and there is no fixed point in the middle, which makes the amplitude of the middle part of the pinion base larger, and the frequent vibration will cause serious wear of the pinion.
Solution: replace the pinion of the ball mill, add two anchor bolts on the inner side of the pinion and the meshing side of the big gear, and reinforce the base again. After the operation, the foundation shall be cleaned first, and the levelness, elevation and position and height of foundation bolts shall be checked.Drill the diameter hole (the size of the hole needs to be determined according to the size of the ball mill), install the anchor bolts, and grouting and pouring. After solidification, use the wedge iron to find the initial alignment. Then adjust the gap between the pinion gear and the large gear, correct the pinion gear by adjusting the height of the wedge, and then perform the second grouting, retain the motor-side half coupling, survey and map the pinion shaft, and redesign the small gear Gear half coupling.
Because the half coupling at the end of the pinion is in interference fit with the shaft, it needs to be hot installed. First, make a test bar that is larger than the online dimension of the shaft, fix the pinion shaft, and then heat the shaft hole of the half coupling. When the test bar can pass through the shaft hole of the half coupling completely, it can be assembled. Put the pinion shaft and bearing into the bearing housing, and adjust the tooth top clearance and tooth side clearance between the pinion and the big gear. Then the gap between the base and the ground shall be grouted twice, and the test run shall be carried out after solidification.It is suggested that if the vibration failure of the ball mill pinion is to be reduced, the ball mill can be installed in accordance with this method
If you would like to get help immediately, PLS click the WhatsApp chat, which is fixed on the left of browser. Meanwhile, you can also fill your requirements on the following form, we will contact you on the right time.
ball mill pinion | prmdrive
Pinion gear is one of the indispensable spare parts of ball mill equipment, according to the direction of tooth shape can be divided into straight teeth and oblique teeth, there are two kinds of key type and expansion type. Different specifications of the ball mill selection of pinion teeth and modulus are not the same. Mainly according to the speed of the mill and the bearing capacity of the gear itself. Regardless of the type of ball mill, the quality of the pinion is of great importance, which directly affects the operation and service life of the equipment.
The gears are forged with ZG45#, 35SiMn, 45MnB, 40Cr and other materials according to customer requirement and drawing, and the hardness can reach HRC40-55 through tempering. Mechanical properties of pinion or shaft gear materials should not be lower than the relevant provisions, tooth surface hardness should be higher than the hardness of big gear tooth surface 30HB above, machining accuracy should meet GB/T 10095.
General situation 1.5, 183, 2.2 meters ball mill is the national standard configuration, gear ring(gear rim) specifications are unified, the rest of the ball mill for non-standard products, manufacturers if need to replace pinion accessories, must know the gear modulus, tooth number and external diameter, internal diameter, stop, displacement coefficient and other data. It is better to have the drawing provided by the mill manufacturer. If there is no drawing, please find a professional to accurately measure the above data and draw a sketch. Provide customized check data to qualified manufacturers.
Module is the ratio of pitch t to PI (m = t/ PI) between the teeth of the same side of two adjacent gears, measured in millimeters. Modulus is one of the most basic parameters in gear manufacturing. The larger the modulus is, the higher the tooth is, the thicker the tooth is. National standard ball mill pinion module is not less than 14, commonly used gear module is 18 module, 20 module, 22 module, 24 module, 25 module, 26 module, 28 module, 30 module. The number of teeth and modulus of gears are set according to the requirements of mechanical and mechanical principles.
There is a minimum number of teeth, is to prevent in the hobbing root cutting phenomenon. Pinion generally must not be less than 17 teeth, pinion number is usually designed for singular, large gear is generally haff-type split structure of the number of teeth for even, and paired with the number of large gear teeth best prime, at least can not be integral multiples of each other, so as to avoid serious local tooth wear phenomenon. So its important to determine the transmission ratio. Balance the relation between the number of teeth and modulus according to center distance and transmission ratio.
Generally divided into two types, one is involute cylindrical spur gear, the other is helical cylindrical gear. Matching gear along the tooth width at the same time into meshing, easy to produce vibration noise, transmission is not smooth. Helical cylindrical gear is better than cylindrical spur gear in grinding machine, and can be used for high speed and heavy load. However, because the manufacturing cost of helical cylindrical gears is much higher than that of cylindrical spur gears, most pinion gears of ball mill on the market are cylindrical spur gears. Pinion and pinion shaft are usually connected in the form of expansion and internal keys.
There are many factors that determine the price of pinion gear. If the pinion gear of the same specification is made of different materials, different manufacturers and different regions, the final price will be different. Mainly is the pinion material and blank weight, followed by the specific requirements and the tedious degree of gear processing.The pinion gears of ball mill manufactured by our factory are all processed by hobbing teeth or grinding teeth, the accuarcy of teeth can up to ISO6, and the tooth surface is quenched with high frequency.
We can manufacture pinion for cement ball mill pinion pinion slag ball mill, ball mill pinion of fly ash, high fine grinding machine pinion, pinion bearing ball mill, sand ball mill pinion, wet ball mill pinion, gypsum ball mill pinion, the overflow type ball mill pinion, ceramic ball mill pinion, dressing ball mill pinion, the grid mill pinion, desulfurization ball mill pinion, the wind sweep gear grinding machine, drying coal power plant coal ball mill grinding pinion, rod mill pinion and so on.
ball mill maintenance & installation procedure
Am sure your BallMill is considered the finest possible grinding mill available. As such you will find it is designed and constructed according to heavy duty specifications. It is designed along sound engineering principles with quality workmanship and materials used in the construction of the component parts. YourBallMill reflects years of advancement in grinding principles, materials, and manufacturing techniques. It has been designed with both the operators and the erectors viewpoints in mind. Long uninterrupted performance can be expected from it if the instructions covering installation and maintenance of the mill are carried out. You may be familiar with installing mills of other designs and manufacture much lighter in construction. YourBallis heavy and rugged. It should, therefore, be treated accordingly with due respect for its heavier construction.
The purpose of this manual is to assist you in the proper installation and to acquaint you a bit further with the assembly and care of this equipment. We suggest that these instructions be read carefully and reviewed by everyone whenever involved in the actual installation and operation of the mill. In reading these general instructions, you may at times feel that they cover items which are elementary and perhaps not worthy of mention; however in studying hundreds of installations, it has been found that very often minor points are overlooked due to pressure being exerted by outside influences to get the job done in a hurry. The erection phase of this mill is actually no place to attempt cost savings by taking short cuts, or by-passing some of the work. A good installation will pay dividends for many years to come by reduced maintenance cost.With the modern practice of specialized skills and trades, there is often a line drawn between responsibilities of one crew of erectors and another. Actually the responsibility of installation does not cease with the completion of one phase nor does it begin with the starting of another. Perhaps a simple rule to adopt would be DO NOT TAKE ANYTHING FOR GRANTED. This policy of rechecking previously done work will help guarantee each step of the erection and it will carefully coordinate and tie it into subsequent erection work. To clarify or illustrate this point, take the example of concrete workers completing their job and turning it over to the machinist or millwright. The latter group should carefully check the foundation for soundness and correctness prior to starting their work.
Sound planning and good judgement will, to a great extent, be instrumental in avoiding many of the troublesome occurrences especially at the beginning of operations. While it is virtually impossible to anticipate every eventuality, nevertheless it is the intention of this manual to outline a general procedure to follow in erecting the mill, and at the same time, point out some of the pitfalls which should be avoided.
Before starting the erection of the mill, adequate handling facilities should be provided or made available, bearing in mind the weights and proportions of the various parts and sub-assemblies. This information can be ascertained from the drawings and shipping papers.
The gearing, bearings, and other machined surfaces have been coated with a protective compound, and should be cleaned thoroughly with a solvent, such as Chlorothene, (made by Dow Chemical). Judgement should be exercised as to the correct time and place for cleaning the various parts. Do not permit solvents, oil or grease to come in contact with the roughened top surfaces of the concrete foundation where grouting is to be applied; otherwise proper bonding will not result.
After cleaning the various parts, the gear and pinion teeth, trunnion journals and bearings, shafting and such, should be protected against rusting or pitting as well as against damage from falling objects or weld splatter.
All burrs should be carefully removed by filing or honing.
Unless otherwise arranged for, the mill has been completely assembled in our shop. Before dismantling, the closely fitted parts were match marked, and it will greatly facilitate field assembly to adhere to these match marks.
The surfaces of all connecting joints or fits, such as shell and head flanges, trunnion flanges, trunnion liner and feeder connecting joints, should be coated with a NON-SETTING elastic compound, such as Quigley O-Seal, or Permatex to insure against leakage and to assist in drawing them up tight. DO NOT USE WHITE LEAD OR GREASE.
Parts which are affected by the hand of the mill are easily identified by referring to the parts list. In general they include the feeder, feed trunnion liner, discharge trunnion liner if it is equipped with a spiral, spiral type helical splitter, and in some cases the pan liners when they are of the spiral type. When both right and left hand mills are being assembled, it is imperative that these parts which involve hand be assembled in the correct mill.
Adequate foundations for any heavy equipment, and in particular grinding mills, are extremely important to assure proper operation. The foundation should preferably be in one piece, that is, with a reinforced slab footing (so called mat) extending under both trunnion bearing foundations as well as the pinion bearing foundation. If possible or practical, it should be extended to include also the motor and drive. With this design, in the event of some movement, the mill and foundation will tend to move as a unit. ANY SLIGHT SETTLING OF FOUNDATIONS WILL CAUSE BEARING AND GEAR MISALIGNMENT, resulting in excessive wear and higher maintenance costs. It has been found that concrete foundations on a weight basis should be at least 1 times the total weight of the grinding mill with its grinding media.
Allowable bearing pressure between concrete footings and the soil upon which the foundation rests should first be considered. The center of pressure must always pass through the center of the footing. Foundations subject to shock should be designed with less unit pressure than foundations for stationary loads. High moisture content in soils reduces the amount of allowable specific pressure that the ground can support. The following figures may be used for preliminary foundation calculations.
Portland cement mixed with sand and aggregate in the proper proportions has come to be standard practice in making concrete. For general reference cement is usually shipped in sacks containing one cubic foot of material. A barrel usually holds 4 cubic feet. Cement will deteriorate with age and will quickly absorb moisture so it should be stored in a dry place. For best results the sand and gravel used should be carefully cleaned free of humus, clay, vegetal matter, etc.
Concrete may be made up in different mixtures having different proportions of sand and aggregate. These are expressed in parts for example a 1:2:4 mixture indicates one bag of cement, 2 cubic feet of sand, and 4 cubic feet of gravel. We recommend a mixture of 1:2:3 for ball mill and rod mill foundations. The proper water to sand ratio should be carefully regulated since excess water increases the shrinkage in the concrete and lends to weaken it even more than a corresponding increase in the aggregate. Between 5 to 8 gallons of water to a sack of cement is usually recommended, the lower amount to be used where higher strength is required or where the concrete will be subject to severe weathering conditions.
Detailed dimensions for the concrete foundation are covered by the foundation plan drawing submitted separately. The drawing also carries special instructions as to the allowance for grouting, steel reinforcements, pier batter, foundation bolts and pipes. During concrete work, care should be taken to prevent concrete entering the pipes, surrounding the foundations bolts, which would limit the positioning of the bolts when erecting the various assemblies. Forms should be adequately constructed and reinforced to prevent swell, particularly where clearance is critical such as at the drive end where the gear should clear the trunnion bearing and pinion bearing piers.
For convenience in maintenance, the mill foundations should be equipped with jacking piers. These will allow the lifting of one end of the mill by use of jacks in the event maintenance must be carried out under these conditions.
Adequate foundations for any heavy equipment, and in particular Marcy grinding mills, are extremely important to assure proper operation of that equipment. Any slight settling of foundations will cause bearing and gear misalignment, resulting in excessive wear and higher maintenance costs. It has been found that concrete foundations on a weight basis should be approximately 1 times the total weight of the grinding mill with its grinding media.
Allowable bearing pressure between concrete footings and the soil upon which the foundation rests should first be considered. The center of pressure must always pass through the center of the footing. Foundations subject to shock should be designed with less unit pressures than foundations for stationary loads. High moisture content in soils reduces the amount of allowable pressure that that material can support. The following figures may be used for quick foundation calculations:
Portland cement mixed with sand and aggregate in the proper proportions has come to be standard practice in making concrete. For general reference cement is usually shipped in sacks containing one cubic foot of material. A barrel usually consists of 4 cubic feet. Cement will deteriorate with age and will quickly absorb moisture so it should be stored in a cool, dry place. The sand and gravel used should be carefully cleaned for best results to be sure of minimizing the amount of sedimentation in that material.
Concrete may be made up in different mixtures having different proportions of sand and aggregate. These are expressed in parts for example a 1:2:4 mixture indicates one bag of cement, 2 cubic feet of sand, and 4 cubic feet of gravel. We recommend a mixture of 1:2:3 for ball mill and rod mill foundations. The proper water to sand ratio should be carefully regulated since excess water will tend to weaken the concrete even more than corresponding variations in other material ratios. Between 5 to 8 gallons of water to a sack of cement is usually recommended, the lower amount to be used where higher strength is required or where the concrete will be subject to severe weathering conditions.
We recommend the use of a non-shrinking grout, and preferably of the pre-mixed type, such as Embeco, made by the Master Builders Company of Cleveland, Ohio. Thoroughly clean the top surfaces of the concrete piers, and comply with the instructions of the grouting supplier.
1. Establish vertical and horizontal centerline of mill and pinion shaftagainst the effects of this, we recommend that the trunnion bearing sole plate be crowned so as to be higher at the center line of the mill. This is done by using a higher shim at the center than at the endsand tightening the foundation bolts of both ends.
After all shimming is completed, the sole plate and bases should be grouted in position. Grouting should be well tamped and should completely fill the underside of the sole plate and bases. DO NOT REMOVE THE SHIMS AFTER OR DURING GROUTING. When the grout has hardened sufficiently it is advisable to paint the top surfaces of the concrete so as to protect it against disintegration due to the absorption of oil or grease.
If it is felt that sufficient accuracy in level between trunnion bearing piers cannot be maintained, we recommend that the grouting of the sole plate under the trunnion bearing opposite the gear end be delayed until after the mill is in place. In this way, the adjustment by shimming at this end can be made later to correct for any errors in elevation. Depending on local climatic conditions, two to seven days should he allowed for the grouting to dry and set, before painting or applying further loads to the piers.
Pinion bearings are provided of either the sleeve type or anti-friction type. Twin bearing construction may use either individual sole plates or a cast common sole plate. The unit with a common sole plate is completely assembled in our shop and is ready for installation. Normal inspection and cleaning procedure should be followed. Refer to the parts list for general assembly. These units are to be permanently grouted in position and, therefore, care should be taken to assure correct alignment.
The trunnion bearing assemblies can now be mounted on their sole plates. If the bearings are of the swivel type, a heavy industrial water-proof grease should be applied to the spherical surfaces of both the swivels and the bases. Move the trunnion bearings to their approximate position by adjustment of the set screws provided for this purpose.
In the case of ball mills, all internal wearing parts will pass through the manhole, whereas in the case of open end rod mills they will pass through the discharge trunnion opening. When lining the shell, start with the odd shaped pieces around the manhole opening if manholes are furnished. Rubber shell liner backing should be used with all cast type rod mills shell liners. If the shell liners are of the step type, they should be assembled with the thin portion, or toe, as the leading edge with respect to rotation of the mill.
Lorain liners for the shell are provided with special round head bolts, with a waterproof washer and nut. All other cast type liners for the head and shell are provided with oval head bolts with a cut washer and nuts. Except when water proof washers are used, it is advisable to wrap four or five turns of candle wicking around the shank of the bolt under the cut washer. Dip the candle wicking in white lead. All liner bolt threads should be dipped in graphite and oil before assembly. All liner bolt cuts should be firmly tightened by use of a pipe extension on a wrench, or better yet, by use of a torque wrench. The bolt heads should be driven firmly into the bolt holes with a hammer.
In order to minimise the effect of pulp race, we recommend that the spaces between the ends of the shell liners and the head liners or grates be filled with suitable packing. This packing may be in the form of rubber belting, hose, rope or wood.
If adequate overhead crane facilities are available, the heads can be assembled to the shell with the flange connecting bolts drawn tightly. Furthermore, the liners can be in place, as stated above, and the gear can be mounted, as covered by separate instructions. Then the mill can be taken to its location and set in place in the trunnion bearings.
If on the other hand the handling facilities are limited it is recommended that the bare shell and heads be assembled together in a slightly higher position than normal. After the flange bolts are tightened, the mill proper should be lowered into position. Other intermediate methods may be used, depending on local conditions.
In any event, just prior to the lowering of the mill into the bearings the trunnion journal and bushing and bases should be thoroughly cleaned and greased. Care should be taken not to foul the teeth in the gear or pinion. Trunnion bearing caps should be immediately installed, although not necessarily tightened, to prevent dirt settling on the trunnions. The gear should be at least tentatively covered for protection.
IMPORTANT. Unless the millwright or operator is familiar with this type of seal, there is a tendency to assume that the oil seal is too long because of its appearance when held firmly around the trunnion. It is not the function of the brass oil seal band to provide tension for effective sealing. This is accomplished by the garter spring which is provided with the oil seal.
Assemble the oil seal with the spring in place, and with the split at the top. Encircle the oil seal with the band, keeping the blocks on the side of the bearing at or near the horizontal center line so that when in place they will fit between the two dowel pins on the bearing, which are used to prevent rotation of the seal.
Moderately tighten up the cap screws at the blocks, pulling them together to thus hold the seal with its spring in place. If the blocks cannot be pulled snuggly together, then the oil seal may be cut accordingly. Oil the trunnion surface and slide the entire seal assembly back into place against the shoulder of the bearing and finish tightening. Install the retainer ring and splash ring as shown.
In most cases the trunnion liners are already mounted in the trunnions of the mills. If not, they should be assembled with attention being given to match marks or in some cases to dowel pins which are used to locate the trunnion liners in their proper relation to other parts.
If a scoop feeder, combination drum scoop feeder or drum feeder is supplied with the mill, it should be mounted on the extended flange of the feed trunnion liner, matching the dowel pin with its respective hole. The dowel pin arrangement is provided only where there is a spiral in the feed trunnion liner. This matching is important as it fixes the relationship between the discharge from the scoop and the internal spiral of the trunnion liner. Tighten the bolts attaching the feeder to the trunnion liner evenly, all around the circle, seating the feeder tightly and squarely on its bevelled seat. Check the bolts holding the lips and other bolts that may require tightening. The beveled seat design is used primarily where a feeder is provided for the trunnion to trunnion liner connection, and the trunnion liner to feeder connection. When a feeder is not used these connecting joints are usually provided by a simple cylindrical or male and female joint.
If a spout feeder is to be used, it is generally supplied by the user, and should be mounted independently of the mill. The spout should project inside the feed trunnion liner, but must not touch the liner or spiral.
Ordinarily the feed box for a scoop tender is designed and supplied by the user. The feed box should be so constructed that it has at least 6 clearance on both sides and at the bottom of the scoop. This clearance is measured from the outside of the feed scoop.
The feed box may be constructed of 2 wood, but more often is made of 3/16 or plate steel reinforced with angles. In the larger size mills, the lower portion is sometimes made of concrete. Necessary openings should be provided for the original feed and the sand returns from the classifiers when in closed circuit.
A plate steel gear guard is furnished with the mill for safety in operation and to protect the gear and pinion from dirt or grit. As soon as the gear and pinion have been cleaned and coated with the proper lubricant, the gear guard should be assembled and set on its foundation.
Most Rod Mills are provided with a discharge housing mechanism mounted independently of the mill. This unit consists of the housing proper, plug door, plug shaft, arm, and various hinge pins and pivot and lock pins. The door mechanism is extra heavy throughout and is subject to adjustment as regard location. Place the housing proper on the foundation, level with steel shims and tighten the foundation bolts. The various parts may now be assembled to the housing proper and the door plug can be swung into place, securing it with the necessary lock pins.
After the mill has been completely assembled and aligned, the door mechanism centered and adjusted, and all clearances checked, the housing base can be grouted. The unit should be so located both vertically and horizontally so as to provide a uniform annular opening between the discharge plug door and the head liners.
In some cases because of space limitation, economy reasons, etc., the mill is not equipped with separate discharge housing. In such a case, the open end low discharge principal is accomplished by means of the same size opening through the discharge trunnion but with the plug door attached to lugs on the head liner segments or lugs on the discharge trunnion liner proper. In still other cases, it is sometimes effected by means of an arm holding the plug and mounted on a cross member which is attached to the bell of the discharge trunnion liner. In such cases as those, a light weight sheet steel discharge housing is supplied by the user to accommodate the local plant layout in conjunction with the discharge launder.
TRUNNION BEARING LUBRICATION. For the larger mills with trunnion bearings provided with oil seals, we recommend flood oil lubrication. This can be accomplished by a centralized system for two or more mills, or by an individual system for each mill. We recommend the individual system for each mill, except where six or more mills are involved, or when economy reasons may dictate otherwise.
In any event oil flow to each trunnion bearing should be between 3 to 5 gallons per minute. The oil should be adequately filtered and heaters may be used to maintain a temperature which will provide proper filtration and maintain the necessary viscosity for adequate flow. The lines leading from the filter to the bearing should be of copper tubing or pickled piping. The drain line leading from the bearings to the storage or sump tank should be of adequate size for proper flow, and they should be set at a minimum slope of per foot, perferably per foot. Avoid unnecessary elbows and fittings wherever possible. Avoid bends which create traps and which might accumulate impurities. All lines should be thoroughly cleaned and flushed with a solvent, and then blown free with air, before oil is added.
It is advisable to interlock the oil pump motor with the mill motor in such a way that the mill cannot be started until after the oil pump is operating. We recommend the use of a non-adjuslable valve at each bearing to prevent tampering.
When using the drip oil system it is advisable to place wool yarn or waste inside a canvas porous bag to prevent small pieces of the wool being drawn down into the trunnion journal. If brick grease is used, care should be taken in its selection with regard to the range of its effective temperature. In other words, it should be pointed out that brick grease is generally designed for a specific temperature range. Where the bearing temperature does not come up to the minimum temperature rating of the brick grease, the oil will not flow from it, and on the other hand if the temperature of the bearing exceeds the maximum temperature rating of the brick grease, the brick is subject to glazing; therefore, blinding off of the oil. This brick should be trimmed so that it rests freely on the trunnion journal, and does not hang up, or bind on the sides of the grease box.
When replacing the brick grease, remove the old grease completely. Due to the extended running time of brick grease, there is usually an accumulation of impurities and foreign matter on the top surface, which is detrimental to the bearing.
Where anti-friction bearings are supplied, they are adequately sealed for either grease or oil lubrication. If a flood system is used for the trunnion bearings and it is adequately filtered, it can then be used for pinion bearings with the same precautions taken as mentioned above, with a flow of to 1 gallons per minute to each bearing.
These lubricants can be applied by hand, but we highly recommend some type of spray system, whether it be automatic, semi-automatic or manually operated. It has been found that it is best to lubricate gears frequently with small quantities.
Start the lubrication system and run it for about ten minutes, adjusting the oil flow at each bearing. Check all of the bolts and nuts on the mill for tightness and remove all ladders, tools and other obstructions prior to starting the mill.
Before starting the mill, even though it is empty, we recommend that it be jogged one or two revolutions for a check as to clearance of the gear and its guard, splash rings, etc. The trunnion journal should also be checked for uniform oil film and for any evidence of foreign material which might manifest itself through the appearance of scratches on the journal. If there are any scratches, it is very possible that some foreign material such as weld splatter may have been drawn down into the bushing, and can be found imbedded there. These particles should be removed before proceeding further.
If everything is found to be satisfactory, then the mill should be run for ten to fifteen minutes, and stopped. The trunnion bearings should be checked for any undue temperature and the gear grease pattern can be observed for uniformity which would indicate correct alignment.
It should be noted that with an empty mill the reactions and operating characteristics of the bearings and gearing at this point are somewhat different than when operating with a ball or rod charge. Gear noises will be prominent and some vibration will occur due to no load and normal back-lash. Furthermore, it will be found that the mill will continue to rotate for some time after the power is shut off. Safety precautions should therefore he observed, and no work should be done on the mill until it has come to a complete stop.
We have now reached the point where a half ball or rod charge can be added, and the mill run for another six to eight hours, feeding approximately half the anticipated tonnage. The mill should now be stopped, end the gear grease pattern checked, and gear and pinion mesh corrected, if necessary, according to separate instructions.
The full charge of balls or rods can now be added, as well as the full amount of feed, and after a run of about four to six days, ALL BOLTS SHOULD AGAIN BE RETIGHTENED, and the gear and pinion checked again, and adjusted if necessary.
Where starting jacks are provided for the trunnion bearings of the larger sized mills, they should be filled with the same oil that is used for the lubrication of the trunnion bearings. Before starting the mill they should be pumped so as to insure having an oil film between the journal and the bushing.
When relining any part of the mill, clean away all sand from the parts to be relined before putting in the new liners. For the head liners and shell liners you may then proceed in the same manner used at the time of the initial assembly.
Before relining the grate type discharge head, it is advisable to refer to the assembly drawings and the parts list.Because of such limitations as the size of the manhole opening, and for various other reasons, it will be found that the center discharge liner and cone designs vary. The cone may be a separate piece or integral with either the trunnion liner, or the router discharge liner. Furthermore, it will be found in some mills that the center discharge liner is held by bolts through the discharge head, whereas in other cases it depends upon the clamping effect of grates to hold it in position. In any event, the primary thing to remember in assembling the discharge grate head parts is the fact that the grate should be first drawn up tightly towards the center discharge liner by adjusting the grate set screws located at the periphery of the discharge head. This adjustment should be carried out in progressive steps, alternating at about 180 if possible and in such a manner that, the center discharge liner does not become dislodged from its proper position at the center of the mill. These grate set screws should be adjusted with the side clamp bar bolts loosened. After the grates have been completely tightened with the set screws, check for correct and uniform position of each grate section. The side clamp bar bolts may now be lightened, again using an alternate process. This should result in the side clamp bars firmly bearing against the beveled sides of the grates. The side clamp bars should not hear against the lifter liners.
When new pan liners are installed, they should be grouted in position so as to prevent pulp race in the void space between the discharge head and the pan liner. Another good method of preventing this pulp race is the use of the sponge rubber which can be cemented in place.
After the mill is erected, in order to avoid overlooking both obvious and obscure installation details, we recommend the use of a check list. This is particularly recommended for multiple mill installations where it is difficult to control the different phases of installation for each and every mill. Such a check list can be modeled after the following:
No. 1 Connecting Bolts drawn tight.
A. Head and Shell flange bolts.
B. Gear Connecting, bolts.
No. 2 Trunnion studs or bolts drawn up tight.
No. 3 Trunnion liner and feeder connecting bolts or studs drawn up tight.
No. 4 Feeder lip bolts tightened.
No. 5 Liner bolts drawn up tight.
No. 6 Gear.
D. Joint bolts drawn up tight.
No. 7 Coupling and Drive alignment and lubrication.
No. 8 Bearings and Gearing cleaned and lubricated.
No. 9 Lubrication system in working order with automatic devices including alarms and interlocking systems.
We further recommend that during the first thirty to sixty days of operation, particular attention be given to bolt tightness, foundation settlement and condition of the grouting. We suggest any unusual occurrence be recorded so that should trouble develop later there may be a clue which would simplify diagnosing and rectifying the situation.
As a safety precaution, and in many cases in order to comply with local safety regulations, guards should be used to protect the operators and mechanics from contact with moving parts. However, these guards should not be of such a design that will prevent or hinder the close inspection of the vital parts. Frequent inspection should be made at regular intervals with particular attention being given to the condition of the wearing parts in the mill. In this way, you will be better able to anticipate your needs for liners and other parts in time to comply with the current delivery schedules.
When ordering repair or replacement parts for your mill, be sure to identify the parts with the number and description as shown on the repair parts list, and specify the hand and serial number of the mill.
By following the instructions outlined in this manual, mechanical malfunctions will be eliminated. However, inadvertent errors may occur even under, the most careful supervision. With this in mind, it is possible that some difficulties may arise. Whenever any abnormal mechanical reactions are found, invariably they can be attributed to causes which though sometimes obvious are often hidden. We sight herewith the most common problems, with their solutions.
Cause A GROUT DISINTEGRATION. Very often when the grouting is not up to specification the vibration from the mill tends to disintegrate the grouting. In most instances the disintegration starts between the sole plate and the top surface of the grouting near or at the vertical centerline of the mill. As this continues, the weight of the mill causes the sole plate and trunnion bearing base to bend with a resultant pinching action at the side of the bearing near the horizontal center line of the mill. This pinching will cut off and wipe the oil film from the journal and will manifest itself in the same manner as if the lubrication supply had been cut off. If the grout disintegration is limited to about . 050 and does not appear to be progressing further, the situation can be corrected by applying a corresponding amount of shimming between the trunnion bearing base and the sole plate near the centerline of the mill in such a fashion that the trunnion bearing base has been returned to its normal dimensional position. If, on the other hand, the grouting is in excess of . 050 and appears to be progressing further, it is advisable to shut down operations until the sole plate has been re grouted.
Cause B HIGH SPOT ON THE BUSHING. While all BallMill bushings are scraped in the shop to fit either a jig mandrel or the head proper to which it is to be fitted, nevertheless there is a certain amount of seasoning and dimensional change which goes on in the type of metals used. Therefore if high spots are found, the mill should be raised, the bushings removed and rescraped. Bluing may be used to assist in detecting high spots.
Cause C INSUFFICIENT OIL FLOW. Increase the oil supply if it is a flood oil system. If brick grease is used, it is possible that the particular grade of brick may not be applicable to the actual bearing temperature. Refer to the remarks in this manual under the paragraph entitled Lubrication.
Cause E EXCESSIVE RUBBING ON THE SIDE OF THE BUSHING. This comes about due to the improper setting of the bearings in the longitudinal plane. In some cases, particularly on dry grinding or hot clinker grinding mills, the expansion of the mills proper may account for this condition. In any event, it can be remedied by re-adjusting the bearing base on the sole plate longitudinally at the end opposite the drive.
There are many more lubricant suppliers, such as E. F. Houghton and Co. , or Lubriplate Division of Fiske Bros. Refining Co. In making your final selection of lubricants, you should consider the actual plant conditions as well as the standardization of lubricants. New and improved lubricants are being marketed, and we, therefore, suggest that you consult your local suppliers.
trunnion bearing assembly ball mill & rod mill
The first part of the mill that we will look at is the TRUNNION BEARING.This is a HYDROSTATIC BEARING which is a slow moving bearing that carries a heavy load. Usually it is constructed from Babbitts metal. If you happen to remember the introduction to this course Issac Babbitt was the man who devised the method of bonding self-lubricating metals onto a strong backing to form a bearing. This type of bearing is named after him. Let us start with the base of this bearing. In it you will notice a SUMP for oil and an oil line that is connected to a PUMP. In the centre of the base is the
BEARING SEAT. There is a hole in the middle of the bearing seat to allow the oil from the oil line to come out of. Radiating away from this hole there are OIL CHANNELS. These are simply grooves cut into the metal to allow the oil to be dispersed over the face of the bearing.
Now this is important, as I mentioned, this is a hydrostatic bearing, it supports a great weight. Because it has a great weight on it, when it is stopped, the oil is squeezed out from between the inner and outer bearing. Before the mill is started up this bearing must have oil injected into it by way of a pump. The pump must be started before the mill begins to turn and must continue until the mill has made at least one revolution.
After that one revolution, what is known as the wedge effect, takes place. The oil that is on the surface of the bearing is forced into a wedge shaped portion of the leading edge of the outer bearing. This will generate enough pressure to lift the entire mill. But if the pump isnt kept pumping for that revolution the weight of the mill as it turns will force the metal of the bearing surface into the oil channels. Two of the required characteristics of these bearings are that they resist dirt contamination and disperse heat well. The result is that the material that the bearing is constructed from is soft. If an oil film isnt present between the two bearing surfaces, the metal to metal contact will cause this damage to the oil channels. Then the bearing will not be able to get enough oil on start up. In extreme cases the bearing may be destroyed.
Once the mill is turning the bearing is self-lubricated by OIL RINGS. They should be checked periodically. If you look closely at them you will notice that they have holes in them. As the rings revolve with the bearing these holes pickup oil from the SUMP in the bearing base and carries it to the top of the bearing. This ring is not joined to the bearing but sits on it loosely.
Because of the drag on the ring by the oil in the sump as the ring is revolved through it, and the lubrication of the oil between the ring and the bearing, the ring turns at a slower rate than the mill does. This is necessary to allow the oil to flow out from under the ring and get caught at the contact point of the inner bearing and the outer bearing. The outer bearing then picks up this oil and maintains the wedge effect.
This cap provides access to the rings and the inner bearing by two ACCESS DOORS on top of the cap. When the bearing and rings are checked through these ports, the person doing the inspecting will be looking at the condition of the bearing surface, verifying that the bearing is being oiled, and that it is free from any grooves or gouges. At the same time, check the rings to be sure they are turning, but at a slower rate than the bearing is.
There is one more piece to complete the assembly, technically it belongs with a following section on liner description, but to avoid confusion I will include it in this portion. It is the TRUNNION LINER, it fits inside the bearing to protect it from wear caused by the ore being washed over the liner and through the bearing as it is fed to or discharged from the mill.
Swivel type lead-bronze bushed trunnion bearings are generally furnished on large diameterball Mills. The bearing swivels are of Meehanite metal spherically turned outside and bored and faced inside to receive the removable bushing. The bushing is bored and scraped to fit the mill trunnion. The bushing is provided with end flanges thus assuring that the trunnion flanges run against a bronze face.
On smaller mills rigid or swivel type bearings support the mill trunnions. The lower half of such bearings are lined with bronze or a special millbabbitt which is peened in place and bored to fit the trunnion.
In all cases a low bearing pressure is maintained to assure freedom from overheating, long life and minimum maintenance. They are designed to provide support to the mill proper, its media and pulp load.
In many dry grinding applications, or where heat is developed, the trunnion bearings can be furnished for water cooling. This system carries away the excess heat transmitted through bearings and protects them.
Lead Bronze has been found to be the most satisfactory bearing material for large diameter bearings, affording the greatest protection against damage of trunnions. Lead bronze will withstand extreme heat for a considerable period of time (for example in the event of lubrication failure). Such heat will cause the lead to sweat out and act as a lubricant itself. This protection eliminates the possibility of scoring a trunnion and there is no danger, as with babbitt, of having the trunnions settle in the bearing and rub on the bearing base.
These are cast heavy in section of Meehanite metal. Where swivel type bearings are used the base is spherically bored inside to gauge to receive such swivels. The bottom of the base is planed to fit a planed top of the trunnion bearing sole plate. The bearing cap is provided with a shroud feature extending out over drip flanges to protect the bearing from entrance of dirt or grit.
Slotted holes are provided in the base for bolting the base to the sole plate; this permits movement of the bearing on the sole plate for adjustment of gear and pinion mesh. Such adjustment is carried out by the use of set screws.
A separate hand operated lubricant jack can be furnished to be mounted on the bearing base or at some distant point to provide a flow of lubricant prior to starting mill rotation. This feature assures lubricant being present at the bottom of the bearing and reflects somewhat in reducing bearing wear and shows a slight reduction in starting torque.
Pinion shaft bearings are of the SKF anti-friction type mounted in a common twin bearing assembly. Bearings are fixed in place so that the pinion shaft of the mill is always in alignment with the drive components. V-belt driven mills are furnished with an outboard bearing of similar construction.
Also available are bearings of the double rigid ring oiling type for special applications. Such bearings are cast integral with a heavy twin bearing sole plate assuring perfect alignment and rigidity. These bearings are equipped with bronze or babbitted bushings.
hd technologies case study: ball mill bearing damage - cbm connect
Asarel Medet AD is among the largest Bulgarian mining companies for the extraction and enrichment of copper ores, located in the territory of Panagyurishte in the Pazardzhik district. The company is recovering and processing about 13 million tons of copper ore annually, producing and exporting copper concentrates and cathode copper.
The customer has an Intellinova online system, mainly Intellinova Standard, comprising twenty-seven Commander Units which monitor 570 measuring points on critical machines in the open pit mine and flotation plant. The equipment in the mine consists mostly of conveyor belts (electrical motors, gearboxes, and rolls) and in the flotation plant of ball mills, autogenous mills, and flotation machines (electrical motors and gearboxes).
SPM HD Spectrum from the NDE bearing shows a clear match of the BPFO (Ball Pass Frequency Outer Race) symptom. According to the customer, following the indications for bearing damage from Condmaster Ruby they replaced the pinion shaft, where they found visible signs of outer race damage on the NDE bearing.
At the beginning (February 2017), the SPM HD trend had varying shock pulse levels HDm/HDc (depending on the load on the mill) from 14/-2 dB (green evaluation) to 29/-3 dB (yellow evaluation). From April 23rd, 2017 the levels started to increase, and after July 2017 they exceeded red evaluation, i.e., alarm status. After September 17th, 2017 the levels reached HDm/HDc = 63/-4 dB (red evaluation). In the SPM HD Spectrum, there were clear BPFO symptom matches for the 22380YMB bearing.
In a continuously operating ball mill, the feed material (copper ore) passes through the central hole of one of the caps into the drum where it is exposed to the grinding media. The grinding of the material occurs during impact with the falling grinding balls and abrasion of the particles between them. Then, the discharge of the ground material takes place through the central hole in the discharge cap or through the grid.
case study: pinion bearing damage in ball mill - spm instrument
Using HD measurement technologies, Bulgarian copper producer Asarel Medet AD monitors the mechanical condition of critical equipment in the open-pit mine and flotation plant. This case study deals with the successful detection of outer race damage on a ball mill pinion bearing.
On the non-drive end bearing, theIntellinovaonline system initially indicated shock pulse levels that varied between green and yellow condition evaluation. This fluctuation was attributed to the operating conditions, with varying loads on the ball mill. Over the following months, bearing condition deteriorated, and when the bearing was replaced during a planned stop about eleven months after the first yellow readings, outer ring damage was verified.