US3374863A

US3374863A - Automatic high pressure lubrication system for rotary grinding mills

Info

Publication number: US3374863A
Application number: US451842A
Authority: US
Inventors: Melvin M Kozlowski; Thomas E Harris
Original assignee: Dominion Engineering Works Ltd
Current assignee: Dominion Engineering Works Ltd
Priority date: 1965-04-29
Filing date: 1965-04-29
Publication date: 1968-03-26
Anticipated expiration: 1985-03-26

Description

March-26,1968 M. M.KOZLOWSKI ETAL 3,374,863

' AUTOMATIC HIGH PRESSURE LUBRICATION SYSTEM FOR ROTARY GRINDING MILLS S Filed April 29, 1965 4 Sheets-Sheet l INVENTORS M. M. KOZLOWSKI T. E. HARRIS I ZmM/g} ATTORNEYS March 1968 M. M. KOZLOWSKI ETAL 3,374,863

AUTOMATIC HIGH PRESSURE LUBRICATION SYSTEM FOR ROTARY GRINDING MILLS Filed April 29, 1965 4 Sheets-Sheet 2 ro TRUNN/ON A BEAR/N6 70 141/11 DRIVE Z05. P/PfSSl/Rf To S/M/LAR srsrs/w o/v Omsk SIDE OF M/tL INVENTORS M; M. KOZLOWSKI T. E. HARRIS A TTORNEYS March 1963 M. M. KOZLOWSKI ETAL 3,374,853

AUTOMATIC HIGH PRESSURE LUBRICATION SYSTEM FOR ROTARY GRINDING MILLS Filed April 29 1965 4 Sheets-Sheet 5 To TRUNN ION BEAR/N6 32 RESERVOIR INVENTORS MXM. KOZLOWSKI T E. HARRIS A TTORNEYS Filed April 29, 1965 March 6, 1968 M. M. KOZLOWSKI ETAL 3,

IGH UBR ATION SYSTEM AUTOMATI PRESSURE L 10 v R ROTARY GRINDING MILLS I 4 Sheets-Sheet 4 INVENTORS M. KOZLOWSKI M T. E. HARRIS i A TTORNE YS United States Patent Filed Apr. 29, 1965, Ser. No. 451,842 4 Claims. (Cl. 184-6) This invention relates to an improved system for the provision of high pressure start-up lubrication for the trunnion bearings of rotary grinding mills, together with an improved means for cont-rolling said lubrication system.

Lubrication of the trunnions during mill operation is provided by rotating oil rings, adjacent each trunnion, which dip into an oil reservoir and carry oil to the upper portions of the trunnions. The oil then flows downwardly over the trunnions and back into the reservoir and thus provides adequate lubrication.

It is well known, however, that one of the most critical periods of rotary grinding mill operation is at the commencement of rotation, or start-up, before the oil rings effectively lubricate the trunnions and when frictional wear due either to an excessively thin layer of lubricant or, worse still, the absence of lubricant, may cause excessive damage to the babbitted trunnion bearings.

The conventional method of providing start-up lubrication for rotary grinding mill trunnion bearings is by I use of a manually operated pump for pumping oil from a reservoir to the underside of the mill trunnions. This system is effective but requires that a man be positioned at each end of the mill to maintain equalized oil pressures at the underside of each of the trunnions.

An improved conventional method uses a motor driven radial piston pump which delivers high pressure oil to the undersides of the mill trunnions and low pressure oil to the tops of the trunnion bearing shells. However, this improved means is only satisfactory when used with low viscosity oil, and thus this system is not practicable for use with large rotary grinding mill installations where it is necessary to use high visosity oil to ensure the maintenance of an adequate film of lubricant.

It is, therefore, the main object of this invention to provide an improved system for the automatic provision of high pressure start-up lubrication for the trunnion bearings of large rotary grinding mills.

Another object is to provide an improved high pressure start-up lubricating system that uses for its operation readily available plant compressed air, a compressor, or any other convenient source of high pressure air.

Another object is to provide an improved high pressure start-up lubricating system which can use either high or low viscosity oils, and which has low maintenance costs due to its nominal requirements of compressed air for operation. 7

Another object is to provide an improved high pressure start-up lubricating system in which the components are of low initial cost and are easy to install, the entire lubricating unit being bolted to existing trunnion bearing base cleanout doors, and thus can be readly adapted to existing installations without any alterations to the existing lubricating systems:

Another object of this invention is to provide an automatic control that will stop the start-up lubricating system when an adequate supply of oil is delivered to the trunnions from the rotating oil rings, or that will continue operation of the start-up lubricating system for a 3,374,863 Patented Mar. 26, 1968 predetermined period of time, irrespective of the number of successive start-ups.

Another object is to provide an improved control means that can be used as a safety device to indicate when the supply of lubricating oil from the oil rings becomes inadequate in time for corrective measures to be undertaken, or to stop the mill motor, before excessive damage is incurred.

A further object is to provide an improved control means which can be electrically connected to the mill motor .to prevent it from starting if the high pressure start-up lubricating system is not operating, and can also be usedto warn the operator, by means of pressure switches, warning lights, sirens, etc., when the high pressure lubricating system is not working properly or fails to function.

. Thus the present invention injects oil at high pressure into the loaded zones of the trunnion bearings during initial mill start-up and, in so doing, lifts the trunnion journals to provide the v necessary running clearance. The control system ensures continuance of the high pressure lubrication during the critical start-up period by continuing the operation of the high pressure lubricating system untl an adequate amount of oil is delivered to the trunnion bearing shell from the oil reservoir bythe conventional rotating oil rings, oil pump, or other means. Only when this condition is fulfilled will the high pressure lubricating system be permitted to stop.

Furthermore, as the mill expands during normal operation due to generation of heat by friction, impact, etc., it necessarily must contract after mill shut down, the contraction depending on the temperature differential between start-up and shut down. The high pressure lubricating system may, therefore, be re-initiated to float the mill trunnions during this cooling off period, and thus eliminate any stresses that may arise in the mill, trunnion bearings, and concrete piers, etc., due to mill contraction.

These and other objects and advantages of this invention will be further apparent by referring to the following detailed specification and figures, in which:

FIG. 1 is a perspective view of a typical rotary grinding mill and shows, schematically, the relative location, on one of the trunnions, of the high pressure lubricating system and the control means therefore.

FIG. 2 is a diagrammatic representation of the components of the high pressure start-up lubrication system for one trunnion bearing.

FIG. 3 shows a circuit diagram of the high pressure lubricating system shown in FIG. 2.

FIG. 4 is a part section of a grinding mill on the line 44 of FIGURE 1 and shows details of the preferred execution of control means.

FIG. 5 is a plan view on arrow 5 in FIG. 4, but omitting the mill trunnion.

FIG. 6- is aside view on arrow 6 in FIG. 4, but omitting the mill trunnion.

FIG. 7..is a view similar to FIG. 4, but showing an alternative execution of control means.

FIG. 8 is a side view, similar to FIG. 6, but showing a further execution of control means.

Referring now to the figures, and particularly to FIG- URE '1, rotary grindingmill 11 is shown mounted for horizontal axial rotation on horizontal trunnions within bearings 12 (only one side shown). Run-of-mine, or coarsely crushed, ore 13 is delivered to mill- 11 along conveyer 14 and enters mill 11 through the hollow centre 15 of one trunnion and is discharged, after undergoing an autogenous grinding process, from the hollow centre of the other trunnion (not shown).

A high pressure start-up lubrication system, shown generally at 16, is attached to one side of the mill bearing support structure and operates to deliver high pressure oil to the underside of the trunnionin bearing 12 at start-up. It will be understood that an arrangement of components similar to system 16 will be attached to the other side of the bearing support structure for raising the other trunnion (not shown) on start-up. Both trunnions will be raised in synchronism.

FIGURES 2 and 3 show details of high pressure startup lubrication system 16 which comprises an air operated double-acting booster pump, shown generally at 17. Pump 17 includes piston 18 which reciprocates Within pneumatic cylinder 19. Piston rods 20 and 21 extend from each side of piston 18 and extend into

oil cylinders

22 and 23, respectively, positioned adjacent each end of cylinder 19. The feed oil for the system is supplied directly from the bottom of the trunnion bearing oil reservoir 24 and is fed through line 25 into

lines

26 and 27. Oil flowing through line 26 passes through check valve 28 into oil cylinder 22, and oil flowing through line 27 passes through check valve 29 into oil cylinder 23. Piston 18 reciprocates, pneumatically, within cylinder 19 and, in so doing, piston rods 20 and 21 alternately reciprocate within

oil cylinders

22 and 23, respectively. Thus, alternately, the oil in cylinder 22 is forced outwardly through check valve 30 and through line 31 into common line 32, and the oil in cylinder 23 is forced outwardly through check valve 33 and through line 34 and into common line 32.

Lines

31 and 34 and common line 32 are flexible high pressure hoses, line 32 leading directly to the underside loaded zone of the trunnion bearing. It should be noted that

check valves

28 and 29 permit the entry of oil into, but not out of,

oil cylinders

22 and 23, respectively,

and

check valves

30 and 33 permit the passage of oil out w of, but not into,

oil cylinders

22 and 23, respectively.

Double-acting booster pump 17 is operated by air under pressure which is supplied through air line 35 to 2- way 2-position solenoid operated valve 36. A similar air line supplies air under pressure to a similar 2-way 2-position solenoid operated valve on the other side of the mill. Solenoid operated valves 36 are opened when the solenoids are energized and are closed by return springs when the solenoids are de-energized.

Timer 37, which is preferably located on the mill control panel, is electrically connected to the mill starter and serves to energize solenoid operated valves 36 on both sides of the granding mill, Thus high pressure lubricating systems 16 on both sides of the mill will be simultaneously initiated by timer 37, on starting the mill.

Energization of the solenoid on solenoid operated valve 36 will open the valve and permit high pressure air to pass through air filter 38 and into pressure regulator 39, then pass through lubricator 40 and into line 41 to 4- way 2-position pilot operated valve 42. Filter 38 cleans the air before it enters system 16 and lubricator 40 mixes oil with the air passing therethrough to deliver a mist for lubrication of double-acting booster pump 17 and other reciprocating components. Pressure regulator 39,

oil cylinder 23, mechanically actuates pilot valve actuator 47 whichconnects air line to pilot valve line 52 and pilot operated valve 42 is moved to the left to permit high pressure air to pass into air line 53, through flow control valve 54 and into cylinder 19 on the right hand side of piston 18. Piston 18 will now move to the left hand side of cylinder 19 and the sequence is repeated, with air line 44 being reconnected to pilot valve line 48 and air line 52 being connected to exhaust outlet on pilot valve actuator 47. It is thus seen that this will be a recurring sequence and piston 18 will automatically re- 7 ciprocate within cylinder 19.

together with pressure gauge 43, is used to adjust the pressure of the air entering system 16.

Air lines

44 and 45 are connected into line 41 and deliver high pressure air to the air inlets on the pilot valve actuators 46 and 47', respectively, on booster pump 17.

Pilot valve actuator 46 is connected between cylinder 19 and oil cylinder 22 and is mechanically actuated, when piston rod 20 is fully extended into oil cylinder 22, to connect air line 44 to pilot valve line 48. This moves pilot operated valve 42 to the position shown in FIG. 3 and air passes into air line 49, through flow control valve 50 and into cylinder 19 on the left hand side of piston 18. This will result in the movement of pistol 18 to the right hand side of cylinder 19. When piston 18 reaches the end of its travel and piston rod 21 is fully extended into oil cylinder 23, piston rod 20 mechanically actuates pilot valve actuator 46 to connect air line 48 to the exhaust outlet 51. Simultaneously, piston rod 21, now fully extended into The speed at which piston 18 reciprocates within cylinder 19 is controlled by air metering needles 56 and 57 on

flow control valves

50 and 54, respectively. Check valves 58 and 59 within

flow control valves

50 and 54, respectively, permit rapid evacuation of air from the de-pressurized side of piston 18 and through exhaust outlet 60 in pilot operated valve 42. I

In the operation of the basic execution of this invention timer 37, for example set to seconds, is operated by activation of the mill starting system whereupon solenoid operated valves 36 are simultaneously opened and pistons 18, within double-acting booster pumps 17, commence to reciprocate and pump oil at high pressure to the undersides of the trunnions within bearings 12. After a predetermined time, for example 60 seconds, another timer 37a is energized by the mill starting system which actuates an air clutch mounted in the mill motor driving shaft to engage the motor drive pinion and the mill starts to rotate, providing the oil pressure in the system is above a pre-set value. Rotation of the mill will start operation of the regular mill oil ring lubrication system, which takes 20 to 30 seconds to build up to effective lubricating operation. Thus this time lag, before the regular system assumes full control of the bearing lubrication, will be more than adequately compensated for by startup lubrication systems 16. When 120 seconds have elapsed timer 37 deenergizes solenoid operated valves 36 and the supply of high pressure oil to the undersides of the trunnions, through systems 16, is stopped.

FIG. 2 includes micro-switch counters 61 and 62, on pilot valve actuators 46' and 47, respectively, which are used to count the number of strokes made by piston rods 20 and 21. Thus, when this execution is used, timer 37 is set, for example, to 120 seconds, and the high pressure lubricating systems 16 started. When counters 61 and 62 each reach a predetermined number, indicating that a predetermined quantity of oil has been pumped to the undersides of the trunnions, then another timer is energized which starts the rotation of the mill, in the manner previously described. Again systems 16 are stopped after 120 seconds of operation.

In the event that, for some reason, the regular mill oil lubrication system does not operate properly, the preferred execution of this invention includes a control, or warning system to indicate that insufiicient oil is reaching trunnion bearings 12 and the high pressure lubricating systems 16 are re-initiated or, if the regular lubrication system should fail during mill operation, then the control system will re-initiate the high pressure lubricating systems 16, or stop the mill, or sound an alarm, etc.

FIGURES 4 to 8 show details of preferred and alternative executions of control systems which are all based upon the fact that the'rotating oil rings in the regular mill lubrication system carry oil to the tops of the trunnions, the oil then falling downwardly over the trunnion surfaces'and back into bearing reservoirs 24. Considering one side of the mill, with the understanding that a similar control arrangement will be provided on both sides of the mill, an axial pocket is formed in the bearing surface, on the approximate horizontal centre line of the trunnion and in the path of the falling lubricating oil in the direction of trunnion rotation. The size of the axial pocket is such that, when the trunnion is receiving an adequate quantity of lubricating oil the pocket will always be filled, but when the trunnion is inadequately lubricated, the pocket will be empty.

Thus the control means illustrated in FIGURES 4 to 8 basically disclose means for indicating the presence or absence of oil in the axial pockets, and include switch means for actuating the high pressure lubricating systems 16 when the absence of oil is indicated.

FIG. 4 is a partial section of the trunnion taken on the line 4-4 of FIGURE 1 and shows details of the preferred control means, and FIGURES and 6 show view taken in the direction of arrows 5 and 6, respectively, in FIGURE 4, but omitting mill trunnion 65.

Mill trunnion 65 rotates in a clockwise direction within bearing shell 66 and babbit liner 67, which are mounted in bearing base 68 and enclosed by hearing cap 69. Axial pocket 70 is formed in bearing shell 66, on the horizontal center line of trunnion 65, and is filled with lubricating oil when the regular mill lubricating system is operating effectively. Pivot arm 71 is pivotally mounted on pivot bracket 72, which is mounted on bearing shell 66. Float 73 is attached to one end of pivot arm 71 and floats on the surface of the oil in axial pocket 70. The other end 74, of pivot a m 71, terminates adjacent, but not touching, the contact 75 of proximity limit switch =76, mounted on bearing shell 66 by means of bracket 77. Thus, when axial pocket 70 is filled with oil float 73 floats on the surface of the oil and maintains the clearance between end 74 and contact 75. However, if the regular oil ring lubricating system fails, axial pocket 70 will drain and float 73 will drop, permitting the other end 74, of pivot arm 71, to actuate limit switch 76, through contact 75, and thus to re-initiate the high pressure lubricating system 16, or to take other remedial measures.

FIG. 7 is a partial section on the trunnion horizontal centre line similar to FIG. 4 but showing details of an alternative execution. Proximity limit switch 76 is attached to bearing shell 66 by means of bracket 78, limit switch 76 being positioned over axial pocket 70. Cylindrical float 79 floats 'freely on the surface of the oil in axial pocket 70 and operatively engages contact 75 when the regular oi-l ring lubricating system is operating eifectively. A plurality of guide fingers 80 are attached to limit switch 76 and serve to maintain the position of float 79 relative to limit switch 76 and also to prevent float 79 from touching rotating trunnion 65. When the regular oil ring lubricating system fails, and axial pocket 70 drains, float 79 will drop and break contact with contact 75, of limit switch 76, causing reinitiation of the high pressure lubricating system 16, or other remedial measures.

FIG. 8 is a side view, similar to FIG. 6, showing details of a further alternative execution. Lever arm 81 is pivotally mounted on pivot bracket 82, mounted on hearing shell 66, and embodies a spoon shape-d portion 83 at one end and a counter weight '84 at the other end 85. Proximity limit switch 76 is mounted on hearing shell 66 by bracket 86 and positioned such that end 85 is adjacent, but not touching, contact 75. A metering orifice 87, of specific diameter, is positioned in spoon shaped portion 83. When the regular oil ring lubricating system is operating effectively lubricating oil will fill and overflow spoon shaped portion 83, orifice 87 and counter weight 84 being so proportioned to provide the balanced lever shown in FIG. 8. If the regular oil ring lubrication system fails, spoon shaped portion 83 will empty and lever 81 will become unbalanced. Counter weight 84 will drop and actuate limit switch 76, through contact 75, causing re-initiation of the high pressure lubricating system 16, or other remedial measures.

Other forms of control system could equally well be devised to indicate the presence or absence of lubricating oil in axial pocket 70, and fall within the scope of this invention, such as a float in the axial pocket which moves up a baflle to cut off a source of light to a photoelectric cell and thus warns of an indequate supply of lubricating oil to the bearings.

What we claim is:

1. In a rotary grinding mill having a grinding drum rotatably supported on coaxially extending journals, having a journal low pressure lubricating system normally operative with operation of the mill to supply lubricant to said journals, the improvement comprising a high pressure lubricant supply means connected to the underside of said journals to provide journal lubricant at sufficient pressure to free and lubricate said journals prior to rotation of the mill, lubricant control means to control the operation of said supply means for a predetermined time interval, and means connecting said control means with the starting system of said mill to initiate operation of said control means whereby on starting the mill said high pressure means is energized to free and lubricate the mill prior to rotation thereof, said predetermined time interval overlapping the commencement of mill rotation to maintain lubrication by high press lubricant until said normally operative lubricating system "becomes effective.

2. The grinding mill as claimed in claim 1 wherein said low pressure system comprises lubricating rings mounted on said journals in oil transporting relation therewith.

3. The grinding mill as claimed in claim 1 wherein said lubricant control means includes a first timer operatively connected with said mill starting system and connected in controlling relation with high pressure pump actuating means, and a second timer connected with said mil-l starting system, having a lubricant pressure sensitive relay in series connection therewith to initiate rotation of said mill in timed succession after initiation of operation of said high pressure supply means, subject to the maintenance of said high pressure lubrication.

4. The grinding mill as claimed in claim 3 wherein said high pressure supply means includes double acting reciprocating pneumatic pump actuators in driving connection with lubricant pressurizing means.

References Cited UNITED STATES PATENTS 1,280,014 9/1918 Goodwin 116-110 2,115,218 4/1939 Cain. 2,661,813 12/ 1953 Kennedy.

3,076,523 2/1963 Fuller et al. 308-122X 3,231,046 1/ 1966 Ohrnberger 184-7 X FOREIGN PATENTS 500,652 3/1954 Canada. 618,407 4/ 1961 Canada. 904,858 2/1954 Germany. 359,605 2/ 1962 Switzerland.

LAVERNE D. GEIGER, Primary Examiner.

E. I. EARLS, Assistant Examiner.

Claims

1. IN A ROTARY GRIDING MILL HAVING A GRINDING DRUM ROTATABLY SUPPORTED ON COAXIALLY EXTENDING JOURNALS, HAVING A JOURNAL LOW PRESSURE LUBRICATING SYSTEM NORMALLY OPERATIVE WITH OPERATION OF THE MILL TO SUPPLY LUBRICANT TO SAID JOURNALS, THE IMPROVEMENT COMPRISING A HIGH PRESSURE LUBRICANT SUPPLY MEANS CONNECTED TO THE UNDERSIDE OF SIDE JOURNALS TO PROVIDE JOURNAL LUBRICANT AT SUFFICIENT PRESSURE TO FREE AND LUBRICATE SAID JOURNALS PRIOR TO ROTATION OF THE MILL, LUBRICANT CONTROL MEANS TO CONTROL THE OPERATION OF SAID SUPPLY MEANS FOR A PREDETERMINED TIME INTERVAL, AND MEANS CONNECTING SAID CONTROL MEANS WITH THE STARTING SYSTEM OF SAID MILL TO INITIATE OPERATION OF SAID CONTROL MEANS WHEREBY ON STARTING THE MILL SAID HIGH PRESSURE MEANS IS ENERGIZED TO FREE AND LUBRICATE THE MILL PRIOR TO ROTATION THEREOF, SAID PREDETERMINED TIME INTERVAL OVERLAPPING THE COMMENCEMENT OF MILL ROTATION TO MAINTAIN LUBRICATION BY HIGH PRESS LUBRICANT UNTIL SAID NORMALLY OPERATIVE LUBRICATING SYSTEM BECOMES EFFECTIVE.