US1386093A

US1386093A - Pttlverizer-mill

Info

Publication number: US1386093A
Authority: US
Publication date: 1921-08-02
Anticipated expiration: 1938-08-02

Description

H. R. COLLINS.

PULVERIZER MILL.

APPFICATION FILED SEPT-9. 1920.

1,386,093. Patented 1921.

4 SHEETS-SHEET l.

H. R. COLLI'NS.

PULVERIZER M|LL.,

APPLICATION FILED SEPT. 9.1920.

1,3 ,093, PatentedAug- 2,1921.

4 SHEETS-SHEET 3.

H. RfCOLLINS.

PULVERIZER MILL.

APPLICATION FILED sums. 1920.

Patented Aug, 2, 1921.

gtSHEETS-SHEET 4.

UNITED STATES PATENT creme.

HARRY RAYMOND COLLINS, OF ALLENTOWN, PENNSYLVANIA, ASSIGNOR TO FULLER- LEI-IIGH COMPANY, A CORPORATION OF PENNSYLVANIA. i

PULVERIZER-MILL.

Specification of Letters Patent.

Application filed September 9, 1920. Serial No. 409,069.

To all whom it may concern Be it known that I, HARRY R. CcLLrNs, a citizen of the United States, residing at Al lentown, in the county of Lehigh, State of Pennsylvania, have invented certain new and useful Improvements in Pulverizer-Mills; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention which relates to pulverizing mills has for its general object the improvement of pulverizing mills of the type shown, for example, in United States patents to J. W. Fuller, Nos. 849,7 7 9, 9,922,468 and 1,039,? 21. In such mills there is a raceway having a number of pulverizing balls therein propelled by a series of pushers, and the pulverized material is removed upward from the grinding zone largely by the suction of inclined blades which lift the finely pulverized material into the field of a super jacent series of fan blades by means of which the material is discharged from the mill.

More specifically considered the presentinvention relates to improvements in a pulverizer mill of the type shown in my copending application Serial No, 836,571,filed November 8, 1919, wherein there is provided a pulverizing mill and air separator unit of improved construction in which all of the moving parts including the fan for producing circulation through the separator and also the feeder are driven from a common shaft connected to a suitable source of power so that their speeds are dependent upon the speed of the mill and variations in the latter are accompanied by corresponding variations in the speed of the other parts of the apparatus. Thus a more uniform operation of theapparatus may be obtained, and the necessity for independent regulation of the speed of the fan and feeder in accordance with variations in speed of the mill is eliminated. In the mill of my co-pending application referred to above, the several sections of the casing are mounted one'above another and carried by a casting resting directly upon the foundation of the mill and the rinding zone is located immediately above the casting so that vibration caused by the moving parts is reduce-d to a minimum.

As distinguished from the usual form of Fuller mill, the mill of my co-pending application contains a relatively short mainshaft which is supported entirely from the lower casing of the mill and is driven from the main counter shaft of the mill by suitable gears. The yoke which carries the arm upon which the pushers are mounted for propelling the grinding balls is set on the end of the shaft in such a manner that it may be conveniently lifted therefrom and removed through one of the upper sections of the mill casing, and the grinding balls and some of the members of the upper hearing. of the main shaft may also be removed through this same door. The yoke itself involves several improvements in its details of construction, particularly the manner of supporting the pushers upon the arm of the yoke and the arrangement for detachably connecting to the body of the yoke the blades for lifting the pulverized material from the zone of action of the balls.

The air current for conveying the pulverized material from the mill to the separator of the unit is produced by a fan mounted at the top of the mill casing and the flow of pulverized material ladened air into the zone of operation of the fan and from thence to the conduit leading to the air separator is controlled by a lantern-like damper provided with means by which it may be adjusted from the outside of the mill.

In the mill shown in my co-pending application, the grinding ring is mounted within a base section which rests directly upon the foundation of the mill, and mounted upon the top of the grinding ring is another section surrounded by a casing into which the air returns from the separator and from which it is directed into the mill by tangential blades extending between the top and bottom of this section. Above the section provided with the tangential blades is a central section in'which is located the door through which the grinding balls, the yoke and other internal parts of the mill may be removed. On top of the central section is another section to the top of which is attached casing containing the fan for producing circulation of air through the mill and the conduit leading to the separator.

The lower bearing of the mainshaft and the gears which drive this shaft are mount ed within a cellar section which is detach- Patented Aug. 2, 1921.

ably connected to the bottom of the base section and may, therefore, be removed to permit access to the mechanism contained within this cellar section. In order, however, to remove a worn grinding ring and replace it by a new one, it is necessary to raise the several sections which constitute the portion of the casing lying above the base section a sufiicient distance to permit the grinding ring to be lifted out of t 1e base section. Such removal of the upper sections of the mill requires that the conduits which connect the mill to the air separator of the unit be disconnected and it is also necessary to provide a crane or other lifting apparatus for raising the heavy upper sections of the mill.

In accordance with the present invention the grinding ring is mounted directly upon the base of the mill, and the upper sections rest directly upon the top of the grinding ring. Surrounding the grinding ring and connected between the base section and the bottom of the section immediately abov the ring is a number of bolts adapted to serve as jacks by means of which the upper sections of the casing may be raised suti'iciently to permit the grinding ring to he slipped out from between these sections and the base upon which it rests. It is there fore required that the upper sections of the mill be raised only a comparatively short distance, so that it is not necessary to disconnect the conduits between the mill and the separator, and the use of cranes or other lifting devices is avoided.

In order that the grinding ring may be withdrawn sidewise, it is necessary to first remove the grinding balls, the yoke and the shaft which extends through the ring. The halls and the yolre may be removed through the door in one of the upper sections of the casing, and in order that the shaft may be withdrawn from the ring, it and both its upper and lower bearings are carried upon the cellar section of the mill so that by dropping the latter the shaf may be withdrawn from the grinding ring, leaving the latter free to he slipped from between the base and the upper sections of the mill as de scribed above.

In order to permit the cellar section with the main shaft to be lowered, the counter shaft which carries one of the driving gears for the mill, is arranged so that it may be moved lengthwise to withdraw its inner end from a bearing in the cellar section of the mill.

The present invention also comprises a number of other improvements in certain features of the mill, such as the lifting blades that are mounted upon the yoke and the damper for controlling the current of air laden with pulverized material that passes" through the mill. The particular nature of these improvements as well as other objects and advantages of the invent-ion as a whole will appear more clearly from a description of a preferred embodiment thereof as illustrated in the accompanying drawings, in which 2-- Figure 1 is an elevation of the mill. partly in cross section and partly as seen from the outside;

Fig. 2 is a sectional elevation of the lower part of the mill;

Fig. 3 shows the position occupied by the several elements constituting the lower portion of the mill when the grinding ring is being removed;

a is a transverse sectional view along the line 44 of Fig. 3;

Fig. 5 is a transverse sectional view along the line 55 of Fig. 1 showing the top of the yoke in plan and the Surrounding casing in section;

Fig. 6 is a detail view of one of the devices for preventing creeping of the grimling ring; and

Fig. 7 is a view of the bottom of the damper, the surrounding casing hein shown in section along the line 77 of Fig. 1.

Referring to the drawings in which similar reference characters denote similar parts throughout the several views, 1() represents the foundation of the mill which is provided with a pit 11 into which the cellar section of the mill may be lowered as will hereinafter appear. Upon the foundation is mounted a base 12 provided with radial passageways 1% closed at their outer ends by suitable caps 14. The grinding ring 15 rests directly upon the top of the base and is prevented from movin sidewise by means of an annular ridge l6 ntted within a ;orrespondingly shaped groove in the top of the base.

Resting upon the top of the grinding ring is a port section 17 which is provided with an annular groove adapted to it over a rresponding tongue 18 at the top of the ring. The .port section 17 is surrounded by a return air chamber formed by a casing 19 to which is connected a conduit 2f! through which the air returns from the separator to the mill. The return air is directed ate the mill by substantially tangential blades or partitions 21 extending between the top and bottom of the port section shown most clearly in Figs. 1, 2, and 5. The return air chamber casing 19 is provided with apertures .to permit access to the interior of the casing for cleaning and repairs, these apertures being closed by suitable covers 22.

On top of the portsection 1. is a central section 23 provided with a door 24 through. which access may he had to the interior of the mill for the purpose of cleaning the same or removing or repairing the yoke or grinding balls. Mounted upon the exterior but which may be of any other suitable construction. As described in detail in that application, this feeder comprises a casing 26 connected to the main casing and carrying a shaft from which is suspended a member having a curved portion upon which material falls from a supply hopper 27, and also a sweeping portion. When the shaft is escillated material is discharged from the curved portion upon the bottom of the feeder casing and then pushed into the passageway leading to the main casing by the sweeping portion. As shown in Fig. l llGlOll],tl1(-} feeder shaft is provided with an arm 28, and there is an adjustable and eccentric connection 29 between the arm and a counter shaft 30 mounted in a bracket 31 attached to the outside of the mill section 23 and connected by means of a belt 32 to a second counter shaft 33. mounted in a bracket 34L likewise attached to the exterior of the section 23. Shaft 33 is driven from the main counter shaft of the mill by a belt Since the feeder constitutes no part of the pres-' ent invention it will not be described in further detail.

on top of the central section 23 is a flaring section 36 to which is attached a cover sec tion 37, provided with bracing ribs 33 adapted to register with corresponding ribs 39 on the section Upon the top of the cover section 37 is mounted a fan casing 40 which is also provided with bracing ribs adapted to register with the bracing ribs of the cover section to produce a strong mounting for the fan and its casing. Connected to the fan casing is a conduit 41 through which the air laden with pulverized material is conducted to an air separator which, since it forms no part of the present invention, is not shown on the drawings. Mounted upon the top of the fan casing is a tripod 4-2 provided at its apex with a cylindrical sorlzet -43 which contains a self-oiling vertical hearing 44: from which is suspended a shaft 45 entering the fan casing 40 through a cover plate 46, which on its upper face, is provided with a bearing 4-7 of any suitable construction to prevent lateral displacement of the shaft, this hearing being preferably provided with a well adapted to be filled from an oil cup outside the bearing. Mounted upon the lower end of the shaft 45 within the casing ll) is a fan e8, of any suitable construction. The shaft is provided with a pulley 49 around which passes a belt 0 running; to the main counter shaft of the mill. In order to change the direction of the belt, it is passed over pulleys 51 mounted in a bracket 52 attached to the fan casing. The tension of the belt may 1 e controlled by means of an idler 53 adapted to be moved forward or away from the belt by a hand wheel The idler is preferably mounted upon an extension of the base 12, as shown most clearly in Fig. 1.

For controlling the amount of air ladened with pulverized material which is drawn from the casing of the mill by the fan 4-8, there is provided a lantern like damper which, shown most clearly in Fig. 1, comprises a cylindrical member 55, provided with ports 56 and attached to a flange 57 at the aperture in the cover section 37. Enciroling the member 55 and supported upon a ledge 58 at the bottom of this member is ainovablc cylindrical member provided "ith ports 60 which may be brought more or less into registry with the ports 56 of the upper member in aeiordance with the amount of air which it is desired shall pass through the damper. The movable member 59 is provided with lugs 61, preferably arranged dianuitrically opposite to each other; to which are connected rods 62 which pass through bushings 63 in the cover section 37. By manipulation of the rods the position of the movable member 59 with relation to the fixed member may be adjusted to control the extent of the openings through the wall of the damper.

The damper described above is constructed substantially the same as shown in my (0- pending application Serial No. 336,571., but in accordanre with the present invention, the bottom of the damper is provided with apertures G l, as shown most clearly in Fig. 7. lilounted within the damper and upon its bottom is circular plate 6' provided with corresponding apertures 66. The plate 65 rarries a lug 67 extending through a slot in thewall of the fixed member and to which is attached a rod (33 passing}; through the wall of section 36 and by means of which the plate 65 may be manipulated to bring); the apertures 66 therein more or less into registry with the aperture (r l in the bottom of the fixed member of the damper. There is thus ywovided mechanism by which the amount of air laden with pulverized material that passes to the fan asing may be closely controlled. and the ports iii the bot tom of the dampe may be controlled independently of those in its wall.

Attached to the bot om of the base 12. is a cellar section or gear housing; 70 provided at one side with an opening into which is fitted a plate 71 which carries a bearing 72 for a main counter shaft 73 slidably mounted in a bearing 74 on a pedestal 75. The shaft carries a pulley 76 adapted to be eonne:;ted by a belt to a suitable source of power, and also a second pulley 77 over which the belt 50 for driving the fan 48 passes. The belt 35 for driving); the ieeder may pass directly around the shaft or around a small pulley 7 8 upon the shaft. I i

&

The plate '71 is connected with a chamber 79 forming an oil well beneath the bearing 72. The main counter shaft 73 carries a collar 80 adapted to lift the oil from the well and allow it to flow through ducts 81 to the interior of the bushing of the hearing. The inner end of shaft 73 is adapted to be supported within a bearing 82 set in a socket formed in the interior of the cellar section of the mill. Near the end of the shaft is a bevel-pinion 83 adapted to mesh with a bevel-gear 8 1 attached to an enlarged portion 85 of the main shaft 86. The enlargement 85 is formed with a tapering portion over the lower end of which the hub of gear 84 fits, while a collar 87 fits over the upper portion and is clamped to the gear by bolts to hold the gear firmly upon the shaft.

The weight of main shaft 86 and the parts mounted thereon is borne by a step bearing at the lower end of the shaft and a bearing beneath the hub of bevel-gear 8%. The step bearing is located in an extension 88 of the cellar section and comprises an adjustable bronze disk 89 and a steel stud 90 at the lower end of the shaft. A bushing 91 detachably mounted within the extension 88 prevents displacement of the lower end of the shaft. Above the bushing 91 is a bridge piece 92 upon which is mounted a member 93 which serves as a bearing for the hub of bevel-gear 84. This bearing is so constructed and proportioned with respect to the bearing at the bottom of the mill as to aid in carrying the weight of the shaft and the parts mounted thereon.

Mounted upon the top of the cellar section 70 and adapted to be clamped between the latter and the base 12 is a conical shaped member 94: upon the top of which is a bear ing 95 for the upper end of the main shaft. This bearing is held in alinement with the lower bearing of the shaft by an inner ring 96. At the bottom of bearing 95 is a duct 97 (see Fig. 3) leading to a pipe 98, adapted to be detachably connected to a pipe 99 which passes through one of the passage ways 13 in the base 12 and carries at its upper end an oil cup 100 which may be additionally supported by means of a bracket 101 attached to the bottom of casing 19. The pipe 99 may be surrounded at the point where it passes out of the passageway 13 by a suitable bushing 102 to prevent escape of material through this passageway. Duct 97 may be provided with a suitable drain cock 103, and at its inner end it is connected with a circular port 104 through which oil may enter the chamber within the bearing 95. The main shaft 86 rotates within a bronze bushing 105 which at its upper end is provided with an outwardly extending shoulder 106 adapted to be attached to a ledge 107 within the bearing 95. A collar 108 is clamped upon shaft 86, and if desired a packing ring may be placed between the collar and the top of bushing 105 to prevent the entrance of dust into the top of the bearmg.

The bushing 105 may be provided with any number of apertures to permit oil to flow between it and the main shaft. At the bottom of the bushin is a packing ring 109 which is held in place by a gland 110 surrounding the main shaft and adapted to be pressed against the ring by a pair of cams 111 upon pivots 112 projecting from the ring 96. The lower ends of the cams are connected to a yoke 113 to which is attached a rod passing through the member 9a and the wall of the base 12 and provided at its outer end with a nut by which the position of the rod and consequently the pressure of the gland against the packing ring may be adjusted to hold the ring against the bottom of the bearing and prevent the entrance of any material into the bearing or leakage of oil therefrom.

The upper end of main shaft 86 is tapered as at 11 1 and upon this tapered end is fitted a yoke 115 which is provided with a depending portion closely surrounding the upper bearing of the shaft to lessen the tendency of pulverized material to penetrate into the bearing. At the top of the yoke is a plate 116 which is fastened to the end of the main shaft to prevent the yoke from being lifted during the operation of the mill.

Projecting outward from the bottom of the yoke are pusher arms 117 of which four are used in the embodiment shown herein although it will be understood that any other desired number may be provided. The pusher arms are adapted to carry pushers for propelling the grinding balls 118, but since the construction of the arms and the pushers constitute part of the invention of my copending application Serial No. 336,571, they have not been shown in detail herein.

Mounted upon the yoke 115 above the zone of action of the grinding balls are lifting blades 119 each having its outer edge bent upwardly as at 120 and provided with such a curvature as will throw the pulverized material toward the center of the mill thus preventing relatively large particles which may be lifted by the blades from being carried out of the mill by the current of air entering through the ports of the section 17 which surrounds the lifting blades. The inner edge of each blade is connected to a bracket 121 which is provided with a vertical rib 122. Suitable bracing ribs 123 are provided beneath the underface of the blade 119 to aid in supporting the latter. The bracket 121 and its ribs are connected to a member 12 1, having a sloping face, which is adapted to fit within a pair of parallel sloping guideways 125 projecting from the .the pair of nuts 132.

side of the yoke substantially midway be tween two of the pusher arms 117 so that the blades 119 will lie above and midway between two of the grinding balls 118. The two guide-ways 125 of each pair are connected at their bottoms by a shelf 126 upon which the corresponding member 124: is seated to hold its lifting blade in place on the yoke. To prevent the blade from being raised during the operation of the mill a pin 127 is inserted through apertures in the top of the guide-way. In order to aid in dislodging the blade the guideways may be provided at their lower ends with apertures into which may be inserted a pointed pin as described in my copending application No. 336,571, these apertures being located partly above the shelf 126 which is provided with a groove 128 corresponding to the lower part of the aperture so as to permit the pin to be driven through these parts to dislodge the lifting blade to permit it to be more easily removed.

The arrangement of the yoke and parts associated therewith upon the upper end of the main shaft 86 permits any of the members mounted thereon as well as the body of the yoke and the grinding balls 118 to he lifted out of the mill through the door 2% in the casing section 23. After the yoke has been removed access may be obtained to the upper bearing for adjusting and repairing in case the cellar section with the main shaft mounted thereon is not lowered into the position shown in Fig. 3.

After continuous service the grinding ring becomes worn and it is necessary to remove it and insert a new one. To permit this to be done it is necessary to lift the upper sections of the casing and for this purpose there is provided a number of bolts 130 connectcd between the base 12 and a flange 131 projecting from the bottom of the port section 17 of the mill. Each of these bolts is clamped to the base 12 by means of a pair of m and to the flange 181 by means of a pair of nuts As the bolts surround the grinding ring it is necessary that some of them be removed when the ring is to be taken out, and for this purpose there is provided an arrangement for detachably connecting the bolts to the base 12 and the is provided with tongues 134 each having a radial. slot 135 adapted to receive the shank of the bolt and a circular recess 136 concentric with the slot and adapted to receive a was ier 137 placed below the upper one of A second washer 138 may be employed in connection with the lo er nut of this pair, but this'washer bears directly against the smooth lower face of the lug 131-. As shown most clearly in Fig. 5 the flange 131 of the port section is provided wn most clearly in Fig. 1 thebase with similar radial slots 139, and concentric with each of the slots at the top of the flange is a circular recess 140 adapted to receive a washer 141 as shown most clearly in Fig. 2. There thus provided an arrangement by which each of bolts 130 may be inserted or removed transversely, and by placing the washers 137 and 14:1 in the corresponding recesses after the bolt has been inserted, displacement of the latter in a sidewise direction is prevented. The arrangement thus permits any of the bolts to be conveniently removed by merely loosening the nuts sufliciently to permit the washers to be taken out of the recesses after which the bolts may be withdrawn from the radial slots.

The weight of the upper sections supplemented by the clamping action of the bolts 130 will ordinarily be suilicient to prevent any creeping of the grinding ring with possible angular displacement of the upper sections of the mill with respect to the base 12, but in order to prevent any such action there is provided a pair of stop blocks having the construction shown most clearly in Fig. 6. Each of these devices comprises a block 142 provided with a depending hook portion 143 ada )ted to fit within the corresponding shaped socket 1&4 in the top of base 12. The grinding ring is provided with an exterior lug 1&5 adapted to serve as a stop for the end of the screw 146 passing through the block 1 12, By tightening the screw the hook portion of the block will be firmly engaged with the side of the socket within which it is placed, thus preventing any dis placement of the grinding ring relative to the base 12 it being understood that the parts will be so arranged relative to the direction of rotation of the grinding balls as to cause the creeping tendency of the ring to force the lugs 145 more firmly against the ends of the screws 146. While in the embodiment of the invention shown herein two of the stop blocks are shown arranged at diametrically opposite points of the mill it will be understood that any other desired number may be used. The grlnding ring is provided with one or more eye bolts 1 .27 to which a rope or chain may be attached for drawing the grinding ring out of the casing.

In the operation of the pulverizer mill described above, the main counter shaft 7 is driven from any suitable source of power and through the gears 83 and 8 1. drives the main shaft 86 whereby the balls 118 will be propelled in the grinding ring 15.

A suiiicient amountof oil will be placed in the cellar section of the mill to lubricate the be, rings of the shaft and the gears connectcams 111 to press the packing ring 109 against the bottom of bushing 105 to prevent leakage of oil from or entrance of dust into the bearing. The depending portion of the yoke 115 which closely surrounds the upper bearing will also tend to prevent the entrance of any dust into the latter. At the same time the feeder will be driven by means of the belt to cause the material to be fed to the mill.

The pulverized material is lifted out of the zone of action of the grinding balls prin -ipall v by the suction effect of the blades" 119 which lift the material into the current of air which enters the casing through the port section 17. On account of the contour of the outer edges 120 of the blades the material will be thrown toward the center of the mill that relatively large particles will fall back into the zone of action of the grinding balls, but the finer particles will be carried along by the air current produced by the fan 1b and from the latter into the conduit a1 leading to a separator.

The volume of air passing through the mill may be closely controlled by the ports in the wall of the damper and also by the ports in the bottom of the same. Further variation of the volume of air passing through the mill may be efiected by change in the sizes of one or more of the gears and pulleys in the driving connection to the fan.

- After the air has passed through the separator and has been relieved of its contents, it returns through the conduit 20 to the return air chamber composed of the casing 19 and again enters the mill to pick up a fresh supply of pulverized material.

lVhenever it is desired to repair or replace any of the pulverizing elements of the mill access to the latter may be conveniently obtained through the door 24 which will be of suflicient size to permit any of the elements associated with the yoke 115 as well as the yoke itself to be removed therethrough. After the yoke has been removed access may be had to the upper bearing of the main shaft, and the parts of the bearing may be removed through door 2 1- Without disturbing the main shaft 86 of the mill. Cleaning and replacing of internal parts of the mill may thus be conveniently performed, but in case it is necessary to remove the grinding ring the main counter shaft 73 is moved lengthwise into the position shown in Fig. 3 to withdraw its inner end from the bearing 82 and disconnect the gear 83 from its companion gear 84-. The free end of the shaft may be supported by placing the plate 71 upon a block 1 18. Afterthe counter shaft unit has been withdrawn the cellar section or gear housing which carries the main shaft and the bearings therefore may be lowered into the pit 11, it being understood that the grinding balls, the lifting blades and the yoke have been previously removed. The cellar section may be lowered by means of jacks or by long bolts temporarily inserted through the bolt holes in the base 12 or by any other suitable means, the sides of the pit 11 being preferably provided with supports 149 upon which the cellar section may rest at the bottom of the pit.

To remove the grinding ring 15 the upper nuts of each pair 183 are loosened, and by manipulation of the lower nuts of these pairs the entire upper portion of the mill may be elevated the desired distance. After this has been done two of the bolts at one side of the mill are removed as indicated in Fig. 4, and the stop blocks 1 12 are disconnected by loosening the screws 146 and tak ing the blocks out of their sockets 1 14;.

The grinding ring is then pried off of the base 12 until the ridge 16 is free. By means of a suitable tackle attached to the eye bolt 147 the ring may then be drawn away from the mill. In case a new ring is to be inserted it is slipped between the base and the elevated upper sections of the mill until its ridge 16 fits within the groove at the top of the base. The upper sections of the mill may then be lowered by manipulation of the lower nuts of the pairs 133 until these sections rest upon the top of the grinding ring, after which the bolts which have been removed may be replaeed as well as the stop blocks 142. The bolts 130 are then set to clamp the grinding ring in place, and the cellar section is lifted into its normal position and attached to the base 12. The counter shaft unit is then moved lengthwise to insert the end of shaft 73 into its bearing 82 and bring the

gears

83 and 84 into ongagement.

In general the entire mill is so designed that the parts most liable to require cleaning or repairs may be reached without dismantling the entire mill, and the elements which require adjustment from time to time such as the gland 110 and the cylindrical damper may be manipulated from the exterior of the mill. It also possesses the further advantage that even the grinding ring may be removed by a comparatively simple operation requiring considerably less time and effort than in the case of a mill such as shown in my copending application in which it 'is necessary to lift the upper sections of the mill through a considerable distance and also to disconnect the conduits leading to the separator.

While a preferred embodiment of the in vention has been shown and described it will.

grinding ring mounted on the base, a casing mounted on the grinding ring and means connected between the base and the casing whereby the latter may be lifted to permit the grinding ring to be laterally removed.

2. A pulverizer mill comprising a base, a grinding ring mounted on the base, acasing mounted on the grinding ring, and jacks connected between the base and the casing whereby the latter may be lifted to permit the grinding ring to be laterally removed.

3. A pulverieer mill eonu'n'ising a base, a grinding ring mounted on the base, a casing mounted on the grinding ring and bolts connected between the base and the casing whereby the latter may be lifted to permit the grinding ring to be laterally removed.

i. A pulverizer mill comprising a base, a grinding ring mounted on the base, means for holding the ring against lateral displacement, a casing mounted on the ring, means for holding the casing against lateral displacement, and means connected between the base and the casing whereby the latter be lifted to permit the grinding ring to be laterally removed.

5. A pulveriser mill comprising a base, a grinding ring mounted on the base, a casing mounted on the grinding ring and means for clamping the grinding ring between the base and the casing and adapted to serve as jacks for lifting the casing to permit the grinding ring to be laterally removed.

6. A pulverizer mill comprising a base, a grinding ring mounted on the base, a casing mounted on the grinding ring, d bolts for clamping the grinding ring between the base and the casing and adapted by manipulation of their nuts to be used as jacks for lifting the casing to permit the grinding ring to be laterally removed.

7. A pulverizer mill comprising a base provided in its periphery with a plurality of radially disposed slots, a grinding ring mounted upon the base, a casing mounted upon the grinding ring and provided in its periphery with a plurality of radially disposed slots, and bolts detach-ably mounted within the slots in the base and casing and adapted by manipulation of their nuts to be used as jacks for lifting the casing to permit the "inding ring to be laterally emoved.

8. it pulverizer mill comprising a base provided in its periphery with a plurality of radially disposed slots and a recess concentric with each slot, a grinding ring mounted upon the base, a CitSlr mounted upon the grinding ring and provided in its periphery with a plurality-of radially disposed slots and a recess concentric with each slot, bolts detachably mounted within the slots in the base and casing and adapted by manipulation of their nuts toibe used as washers upon the bolts and adapted to lie within the recesses for holding the bolts in place.

S). A pulverizer mill comprising a base provided in its periphery with a plurality of radially disposed slots having semi-circular inner ends, said base being also provided with circular recesses concentric with the inner ends of the slots, a grinding ring mounted upon the base, a casing mounted upon the grinding ring and provided in its periphery with a plurality of slots and recesses similar to those in the base, bolts detachably mounted within the slots in the base and casing and adapted by manipulation of their nuts to be used as jacks for lifting the casing to permit the grinding ring to be laterally removed, and circular washers upon the bolts and adapted to lie within the recesses for holding the bolts in place.

10. A pulverizer mill comprising a base, a grinding ring mounted on top of the base, a casing mounted on top of the grinding ring, means connected between the base and the casing whereby the latter may he lifted to permit the grinding ring to be removed, grinding balls in the ring, a housing detachably secured to the bottom of the base, a shaft mounted in the housing, and means on the shaft for propelling the grinding balls.

11. i pulverizer mill comprising a base, a grinding ring mounted on top of the base, a casing mounted on top of the grinding ri means connected between the base and the casing whereby the latter may be lifted to permit the grinding ring to be removed, grinding balls in the ring, a shaft, means on the shaft for actuating the grinding balls, and a mounting for the shaft detachabl secured to the base whereby the shaft ma be lowered through the ring to permit the latter to be removed edgewise from the mill.

12. A pulverizer mill comprising a base, a grinding ring mounted on top of the base, grinding balls in the ring, a shaft extending through the ring, means on the shaft for actuating the. grinding balls, a member detachably secured to the base and provided with bearings for the shaft, a casing resting upon top of the grinding ring, and means connected between the base and the casing whereby the latter may be lifted to permit the grinding ring to be removed sidewise after the member carrying the shaft has been detached from the base and lowered to carry the shaft out of the path of the ring.

it. pulverizer mill comprising a base, a grinding ring resting upon the base, grindballs in the ring, a casing resting upon the grinding ring, means connected between the and the casing for raising the latter to permit the grinding ring to be removed, a housing detachably secured to the base, a

main shaft mounted in the housing and extending through the ring, means on the shaft for propelling the grinding balls, a gear on the shaft, a counter-shaft having its inner end supported in a bearing in the housing and provided with a gear engaging the gear on the main shaft, said countershaft being adapted to be moved lengthwise to disengage the gears and withdraw its inner end from the housing to permit the latter to be lowered so that the main shaft may be withdrawn from the ring when the latter is to be removed from the mill.

ll. A pulverizer mill comprising a base, a grinding ring resting upon the base, grinding balls in the ri" V v a casing resting upon the grinding ring, means connected between the base and the casing for lifting the latter to permit the ring to he removed edge wise, means for propelling the grinding balls including a shaft extending through the ring, a mounting for the shaft detachably secured to the base so that it may be lowered to withdraw the shaft from the ring when the latter is to be removed, and a driving connection for the shaft adapted to be disconnected therefrom when the mounting is to be lowered.

15. A pulverizer mill comprising a base, a grinding ring resting upon the base, grinding balls in the ring, a casing resting upon the grinding ring, means connected between the base and the casing for lifting the latter to permit the ring to be removed edgewise, means for propelling the grinding balls including a shaft extending through the ring, a mounting for the shaftdetachably secured to the base so that it may be lowered to withdraw the shaft from the ring when the lat ter is to be removed, and means for driving the shaft including a counter-shaft geared thereto and adapted to be moved lengthwise to disconnect the gears when the, mounting is to be lowered.

16. A pulverizer mill comprising base, a grinding ring resting upon the base, a casing resting upon the grinding ring, means for preventing creeping of the grinding ring, and means connected between the base and the casing whereby the latter may be lifted to permit the ring to be removed.

17. A pulverizer mill comprising a base, a grinding ring resting upon the base, a casing resting upon the grinding ring, means connected between the base and the casing whereby the latter may be lifted to permit the ring to be removed, and devices for preventing creeping of the grinding ring each comprising a hook adapted to fit within a socket in the base, and means on the ring cooperating with the hook for preventing movement of the ring.

18. A pulverizer mill comprising a base, a grinding ring resting upon the base, grinding balls in the ring, means for propelling the grinding balls, and means for preventing creeping of the grinding ring on the base due to the movement of the balls therein, comprising lugs on the periphery of the ring, hooks secured to the base and screws in the hooks engaging the lugs whereby the hooks and screws resist movement of the ring.

19. A pulverizer mill comprising a base, a grinding ring resting upon the base, grinding balls in the ring, a housing detachably connected to the bottom of the base, a shaft, a lower bearing for the shaft mounted at the bottom of the housing, an upper bearing for the shaft mounted on top of the housing, and a member carried upon the upper end of theshaft and provided with a plurality of arms for propelling the balls when the shaft is rotated.

20. A pulverizer mill comprising a casing, means within the casing for pulverizing material, a conduit leading from the top of the casing and adapted to be connected to a separator, a fan at the top of the casing for forcing current of air laden with pulverized material through the conduit, a cylindrical member mounted within the casing at the top thereof and provided with a bottom having a series of ports therein, a movable, circular member mounted upon the bottom of the cylindrical member and provided with ports adapted to register with the ports therein, and means connected to the movable member and extending to the outside of the casing whereby the position of the movable member may be adjusted to regulate the amount of air which may pass through the ports to the fan.

21. a pulverizer mill comprising a casing, means within the casing for pulverizing material, a conduit leading from the top of the casing and adapted to be connected to a separator, a fan at the top of the casing for forcing a current of air laden with pulverized material through the conduit, a cylindrical member mounted within the casing at the top thereof and provided with ports in its wall and having a bottom provided with ports, a movable cylindrical member associated withthe first named cylindrical memher and provided with ports adapted to register with the ports in the wall thereof, a circular member movably mounted upon the bottom of the cylindricalmember and provided with ports adapted to register with the ports therein and means whereby the movable cylindrical member and the circular member may be independently adjusted from the outside of the casing to regulate the amount of air which may pass through the ports to the fan.

22. A pulverizer mill comprising a casing, a, grinding ring, grinding balls in the a shaft of abbreviated length at the ring, bottom of the casing, a member mounted on and inclined blades mounted in the member above the arms for lifting material out of the zone of action of the balls, said blades being provided with outer, vertical edges having a curvature adapted to deflect the material toward the center of the casing as it is lifted.

23. A pulverizer mill comprising a casing, a grinding ring, grinding balls in the ring, a shaft of abbreviated length at the bottom of the casing, a member mounted on top of the shaft and provided with a plurality of arms for propelling the balls through the ring when the shaft is rotated, brackets detachably mounted on the member, and inclined blades at the outer ends of the brackets having their outer edges bent upward and curved in a manner to deflect the material toward the center of the casing as it is lifted by the blades.

In testimony whereof I afiix my signature.

HARRY RAYMOND COLLINS.