US2530313A - Feed device for rotary beater mills with means for preventing blow-back of material - Google Patents

Description

2,530,313 FOR ROTARY BEATER MILLS WITH MEANS Nov. 14, 1950 c. D. PARTEN FEED DEVICE FOR PREVENTING BLOW-BACK OF MATERIAL Filed June 2, 1947 ..-D7/J. w

Patented Nov. 14, v1950 FEED DEVICE FOR ROTARY BEATER MILLS WITH MEANS FOR PREVENTIN G BLOW- BACK OF MATERIAL Carl D. Parton, Minneapolis, Minn., assignor to Schutz-@Neill Co., Minneapolis, Minn., a, corporation of Minnesota Application June 2, 1947, Serial No. 751,846

l Claim.

rlhig invention relates to a device for grinding solids to a fine state of subdivision. More particularly, it relates to an improved mounting for the parts of the VVgrinding machine and to improved means for rsupplying material to be ground to the grinding chamber.

In the grinding mills `'of the screen type as heretofore known, vexcessive vibration and wear of the parts has been a common experience. Another difculty in suchdevices is found in the means for supplying material to be ground to the -grinding chamber. The means for supplying material in the grinders heretofore known, particularly in hammer mills of the screen type, has been a simple hopper of decreasing cross-sectional area, which merely directs the material to be ground into the chamber. With hoppers of this type, there is considerable throwing back up into the hopper of material supplied tothe grinding chamber lunless the rate of feed of material to the grinding chamber is -kept low, not to mention the other obviousdisadvantages of such a structure.

An object is to provide agrinding machine such las a hammer Ymill pulverizer -of the screen vtype having improved means for supplying material to be ground -to Athe grinding -chamber whereby the capacity of the ymill is increased. -1

A f-u'rther `object is to provide a hammer mill pnlverizer of the 4scr-een type lincluding means-for suppl-ying material to be lground -to the grinding chamber in which material thrown lback from the grinding chamber is caught and returned to ,the grinding `chamber without .escaping into the atmosphere. -Y Y .therv objects will :appear hereinafter.

yEhe means by which-the lforegoing objects have been accomplished vare embodied in -the illustrative devices show-n inthe accompanying drawings which forma partofithis specification rand in which.:

Figure 1 is a view, partly in central vertical cross-section, of a fpul-ver'izer embodying'features of the present invention;

Figure l2 isa vertical cross-sectional view -on the line 2?-2 in Figure l.; Y

Figures 3, 4, t5 and Y6 are views similar to Figure 2 showing .modified forms of feeding means.

As shown in Figure l, the rgrinding machine .generally-designated It includes a base I2 having a passageway I4 extending longitudinally thereof between a grinding-chamber I 6 at one end and a rblower chamber i8 at the other. Formed integrally with the ibase at each end thereof are verticallyxtend'ing walls i250 and l2|2 and associated (Cl. ,ZU-186) walls 24 and 26 extending at right angles thereto, which 'partly enclose the lower portion of the chambers l and I8. The walls 20 and 22 Vboth terminate about midway of the chambers I6 and 'I8 respectively, and are provided 'at their upper edges with flanges l2| and 23. 'Ihe upper portion of the chambers I6 ,and I8 is partially enclosed by a `pair of semi-cylindrically housings 25 and 21, open on one end. These housings 25 and 21 are flanged as at 29 Aand 3| along their lower edges, and are secured kin place by fastening means extending Athrough the respective pairs of vflanges 29-2I `'and 3 I23. The closure-of chambers I6 and I8 is completed by plates 28 and 30 respectively, which are bolted to flangesv32,133, 34, and 35, formed respectively on housing '25, `base I2, housing 21 andzbase I2.

A pair of bearings 36 and 38 are mounted on the :base I2 between the walls 2U and 22. The shaft 40 is rotatably mounted on these bearings.

.At yone end in the chamber I5 the shaft 4D has a set of three discs '42 fixed thereon. These discs carry hammers or beaters 44. On the other end of the shaft 40 in chamber I8 a set of blower lblades 46 is fixed on shaft 4l). Between the bearing members'SB and 3B the shaft 4U carries a driving pulley 4:8.

The balance obtained in this structure is readily apparent .from the drawings. By having the driving pulley 48 mounted in the center of the Vshaft 40, the two driven members on either end and the bearings between the driving pulley and the respective driven members, as nearly a perfect balance as possible is obtained. The central location of the bearings also contributes to improved `operation of this pulverizer, and the fan and beaters are readily accessible.

As indicated above, the pulverizer which forms the subject 'of this invention, in 'addition to the improved arrangement of the parts, is also pro- 'avided with inovel means for feeding material to be rground into the 'grinding chamber. In general, the feeding means shown in Figures 2 ithrfough '6 are :characterized by the feature that they permit material supplied to the grinding 'chamber .to be 'thrown back without permitting the rmaterial so thrown back Vto escape into the atmosphere.

In the embodiments Yof Figures 2 and '3, it -will be seen that the material to be ground is 'fed :into Ithe grinding fchamber in :a generally radial direction, whereas in Figures 4, 5 and 6 the material to .be :ground is fed into the :grinding zchamberin a :direction which :is substantially tangential :to the rotating 'grinding'memben "ruga'ted section 14.

ing 25, a portion 5B extending vertically upwardlyv c from the portion 54, another portion 58 extending horizontally from the vertical portion 55, and nally, a portion 6U which extends upwardly at an angle of about 45 from the horizontal portion 58. The open end of the portion 54 is-provided with a flange 62 which is secured to the housing 25 by any suitable means, such as welding. At the junction of the horizontal portion 58 and the vertical portion 55 a semi--circular baille 64 is secured within the horizontal section 53 to completelyl block the upper half thereof. Material to be ground is first filled into the portion B5 of the conduit. Feed of material in the portion 65 is controlled by an adjustable feed gate 66 mounted in the portion 55. The gate 55 is slidably mounted in a slotted guide 58 secured to the conduit member .55 with its slot in alignment with a corresponding slot through conduit section 52. 'mounted in the guide 68 permits the feed gate A set screw 19 65 to be secured in any desired position.

As indicated by the arrow 12 in Figure 2, the

vdiscs 42 in the embot'iment oi' the invention shown in 1Figure 2 rotate in a clockwise direction when viewed from the end of the shaft 45 on which these discs Vare mounted. Material sup- Ltion 14 which may be removable is secured to 4the inner surface of the annular wall portion 15 oi the housing 25 between the opening 55 and the lower end of the wall portion 15 on the other side' of chamber I 6.

" 'The maximum size of ground material leaving "thegrinding chamber I5 is determined by a 'screen 18 mounted in the lower portion of the chamber. The screen 18 is provided at its upper rend with flanges 85 andl 52 which are secured' at either side of chamber IB between flanges and 2I, which are suitably relieved at these points to ac'commodate the flanges 85 and 82. "the vertical wall 2B and the end plate 28 a pair of Between side walls 84 and 86 extend inwardly and clown- Ywardly from the vertical walls 24 and join a bot'- tom wall 88 'of base I2, which is a continuation ``r; .of the lower wall of the conduit I4. rIhese walls complete the closure of the chamber I6. The lower portion of chamber I6 opens into the conduit I4 through an opening B0 formed in the vertical wall 20.

In the operation of a pulverizer embodying the features illustrated in Figure 2, material to be kground is lled into the conduit portion Ell, the

feed gate 66 is positioned to give the desired rate of feed, and the material to be ground passing s beyond this gate proceeds through the horizontal conduit 58 past the baille 64, downwardly through the vertical conduit 56, and then through the radially extending conduit 54, and enters the chamber I6 through the opening 50. The hammers 44 are moving in the direction indicated by -the arrow 12, and they pick up the material entering chamber IB and throw it against the cor- In this manner the large pieces of solid material are disintegrated or pul- 4 verized, and as they are carried around by the rotating grinding member, they are eventually brought to the screen 18 through which a portion of the material which is line enough passes. A ian such as the fan 46 pulls air through the conduit I4 from chamber I5, drawing with it the ground material passing the screen 18, The air carrying the ground material is discharged through the exhaust 52 of the fan 46 to suitable collection means. By reason of the construction of the conduit 52, it is possible to operate under conditions such that a considerable portion of the material supplied to the chamber I6 is blown back through the opening 5I), as, for example, by rotating the hammers 44 at relatively high speed or by supplying material to be ground to the grinding chamber at a relatively high rate. The advantage of operating under conditions where a lot of material is blown back through the opening 5B is that maximum grinding capacity is obtained under these conditions, that is to say, the

grindingcapacity of a given unit increases within certain limits as the amount of material blown back through the opening increases. In previously-known pulverizers it was not possible to operate with any substantial amount of blowback through the opening into the grinding chamber because the material so blown back escaped to the atmosphere and was'lost or else forced fresh material being supplied to the grinder to be thrown into the atmosphere and lost, or both. These losses are prevented by the conduit 52. The velocity of material blown back through the opening 55 is spent. by impact with the Walls of the conduit portions 54 and 55 particularly. Material deflected by these walls is caught, at least in part, by the baille 64. Any small amount which escapes past the baille 64 spends itself against the feed gate 66 or is caught and carried back toward the chamber I6 by the material being supplied to the grinder through the conduit portion 65. This material lmoving through theporand thus takes the place of portions 54 and 56 in the conduit 52. 96 joins a horizontally-extending portion 98,

Vertically-extending portion which is in turnv joined by portion It extending up at an acute angle. It will be seen that these latter two portions correspond respectively to the portions 58 and 60 of conduit 52. Material to be ground is supplied to the open end of the conduit IUD, and the rate of feed thereof toward the chamber IE is controlled by feed gate |02, which, like the feed gate 56, is mounted in a slotted guide m4, secured to the conduit |50 in line with an opening therethrough. Gate |52 is slidable in the guide |04 and may be secured in any desired position by the adjustment screw H16. The flange 08, formed on the open end of the conduit portion 96 is secured to the housing 25 by welding or other suitable means. A baille I I0, identical with the baille 64, is secured inside the conduit at the junction of the vertical portion 86 andthe horizontal portion 98.

The direction of rotation of the hammers 44 in th'e embodiment of Figure 3 is not material due to the central location of the opening 92. By way of illustration, the arrow H2 is included tofshow that the hammers 44 can )be rotated in a clockwise direction, as in the vembodiment of Figure .2. A corrugated 'section v-I'I-4, simi-lar to the section 14, is secured to the annular wall 16. Due'to the location of the inlet to the chamber I6, it is necessary to lprovide an opening I'IG through the corrugated section I I-4,^which is positioned in alignment with the opening 92. v Y The embodiment of Figure 3 is other-wise iden-Y tical with that of Figure 2. It includes the same .screen i3 having anges 8|] and B2, which are clamped bet-Ween the flanges 29 and 2| to hold :the screen in place. It also .includes the wal-ls 84, 85, and B8, completing the closure -of the bottom of the chamber, and it includes the opening 9i) through the wall 2t. The operation of the .embodiment of Figure 3 is also similar to that of VvFigure 2. Material to be ground, enter-ing the chamber I6 radially through the -openingsii and |46, is engaged by the hammers 44 and driven Vvagainst the corrugated Ysection .I I4. Ground material eventually passes through the screen 18 and vis carried by a current of air through vthe conduit I4 and discharged-by a f-an 43 -through an exhaust s2 to suitable collection means.

The main advantage of the embodiment shown in Figure 3,-as compared with -other embodiments, is that it is relatively easy to construct. There is lslig-htly less blow-back -in this form under otherwise equivalent conditions. Material which vis Vblown back through the openings 92 and H6 spends its force mainly against the walls -of conduit section ed and against the :bariile Iie'l. Any small amount of 'material which does `pass the ,baiiie IIS is caught by the gate |02 or the material moving past the gate -in the manner already described above in connection with Figure 2.

The embodiment of Figure 4 :gives the maximum single pass grind; that is., the maximum amount of grinding for a :single passage of material through the pulverizer, and, accordingly, this .embodiment provides the `maxim-um capacity for a given size of machine. In Figli-ree the opening Ii' in wall "It, through which material .to be ground is supplied to the chamber I5, like ythe opening till, is located just above the flange 29. It is of the proper size and shape to conform vwith the `vertical portion |20 `of the conduit |22, which directs the material to be ground into the grinding chamber i5, through the opening I I'S in .a direction which is tangential to the path. of the movement of the hammers 44. Because this embodiment involves the maximum amount of blow-bach through the opening into chamber iii, the horizontal conduit section |24 joins `the vcrtical rportion |223 lintermediate its ends, thereby providing a surge chamber |25 in the upper part .of the vertical conduit portion |29. The size of this surge chamber .|25 is further increased by -thebailie |23, located at the junction ci the ver- Vtical conduit I and the horizontal section |24. As in the other embodiments, the horizontal sec- .tion |24 in turn communicates with a portion l|355` extending upwardly at an angle to the verztical. A flange i312, `formed on the lower end of the vertical portion |20, Ais secured by riveting or welding or any other desired means to the housing 25 to hold the conduit i22 in place. A feed gate |34 is slidably mounted in a guide |35 secured to the conduit .portion |33 in alignment with an opening therethrough. An vadjustnflent screw 33 permits the gate |34 to be secured in any-desired position.

Figure 4. also illustrates a feature of construction lwhich can be included .with `any .of the .em-

bodiments yshown iinaarry offthe yother:iiguresnto provide :better control of lthe, head =of pressure o f .the material to'befground, which is bein-g supplied through the conduit portion .130. ',Io. this end, the portion |30, :intowhich the material to .be ground is supplied, instead of .being rigidly connected'to thehorizon-tal conduit. section |24,1s pivoted thereto iat YI4!) at the` uppermost Ypoint off-the junction-of the two ysections and over lthe remainder of its :circumference is -slidably extendedwithin the horizontal portion |24, which, for vthis purpose, is vextended outwardly --.and curved upwardly aaswndicated at |42. In vthis wayithefsection |30 can be adjusted to various angles with the vertical', at all of--which there -is a tight'j-om-t between .sections;|24.,and |30. It is apparent, of course, that with-*aggiveni amount of' material Yin the conduit T30, the'head of pressure Aat `feed gate |34 depends upon the angle with respect tothe vertical at which the portion i3d, egtends.- c g lrIhe embodiment of Figure 4 is particularly characterized by the fea-ture that the `material to be ground -is .supplied to the -chamber I6 tangentially in adirection .oppositegthat in which the hammers 44 lare :moving adjacent the inlet fIfIS.. T-he direction of rotation of the hammers 44 is, accordingly, u'as indicated bythe arrow |44. Between theinlet VI I8 `and the opposite-side of .the housing 2.0;a corrugated section |46 is secured to the 4wall 1-6 to cooperate with hammers 44, as :inthe other-embodiments described above. The ylower half of the grinderstructure `is `identical with that in t-he other embodiments and has al-readybeen described above.

'The operation of vthe structure illustrated 1in Figure .4 is las follows: The conduit'section .|30jis set at the appropriate angle to provide the desired head :at the feed gate |34. .Material supplied .to the conduit section |139 moves .pa-st the feed gate ,4.34 through the 1section V|24 and `thence downwardly to chamber4 |16.; After v:it is ground, the material passes, as in the other embodiments, through screen 18 land is eventually carried to a collection means by a current of air. It has already been pointed out above that this particular form gives maximum feed-.back `through the opening IIS, and, accordingly, additional provision is made in the-conduit |22 tospend the force .of the material fed back and prevent ity V,from escaping to the` atmosphere. It is a particular advantage of this embodiment that the material being ground can be caused to feed back the larger particles until they are broken up suinciently so that they :no longer Vhave weight enough `to oppose the head of pressure of thefresh material coming in to be ground. In 'this manner, a sort of automatic separation -and .regrinding of the larger particles is obtained.`

In contrast `to the embodiment of Figure L4, that of Figure 5 provides a minimum of feedback. The opening :|48 `in the wall 16, through which material to be ground enters chamber I6, is located near the top of the housing 25. Because of the flow feed-back, the conduit `.15.0, through which material to .be ground is brought to the opening |48, is 'relatively simple in structure. As may be seen, it vincludes a portion |52 extending generally tangentially with respect to the path of travel of the hammers 44 adjacent the opening |48. The Yportion V|52 joinsfasecond portion |54, extending generally vertically. This portion |54 is shown as somewhat enlarged :in cross-sectional area over the .portion |52. In any of the embodiments shown,ithezporton .of

the conduitinto which the material to b'e ground 'is first supplied may, if desired, be considerably enlarged overl the remainder of the conduit and may include a hopper, if desired. To provide meansfor securing the conduit |50 to the housing 25, the open end of section |52 is provided with a flange' |56, which is welded or otherwise fastened to housing 25 about the opening |48. The conduit section |52 is provided with a feed gate structure which, like the others previously described, includes a gate |58, a guide |68, and an'adjustment screw |62. Inthis embodiment, in which the hammers rotate in the direction in- 'dicated by the 'arrow |64, blow-back is largely or completely 'prevented by providing a baffle |66. Ihe baille |66 is shaped to close o the upper portion ofthe conduit section |52 when it extends generally radially with respect to the discs 42. As in the other embodiments, a corrugated section |68 is secured to the Wall 16 of housing 25. An opening |10 is provided in the corrugated section |68 in alignment with opening |48. The lower half of the grinding chamber structure, which is the same as that in the other embodiments, has already been described.

The embodiment oi Figure 5 operates with a minimum of blow-back since the material to be ground, moving past the gate |58, enters the chamber |6 in a direction tangential to the path of movement of the hammers 44, and at its point of entry is moving in the same direction as the hammers. Actually, in this form the rotating hammers tend to pull material into the chamber rather than to blow it back, as in the structure of Figure 4. Any small amount of material which may tend to blow-back is caught by the baffle |66 and returned to chamber I6. Thus, in Figure 5, the blow-back problem is solved mainly by minimizing the amount of material which leaves chamber I6, rather than by providing a circuitous conduit in which the force of the material blown back maybe spent against the walls.

:In the 'structure shown in Figure 6, the conduit |122 extends into the chamber |6 which is enlarged'by replacing the curved wall 16 of housing on one side with a vertical wall |14. The hammers move in the direction indicated by the arrow |13 and the Wall of conduit |12 thus serves' as a'bafe. Material being ground is thrown up into the space between the lower part of the Wall of conduit |12 and the vertical wall |14 and then falls back into the periphery of the mill again.

Plate 28 and wall 25 are extended out to the wall |14 to complete the closure of chamber 6. Conduit |12 extends into chamber I6 at about the same angle as conduit |58 through an opening |16. This conduit is generally the same in structure as conduit |50 and only the lower portionzwhich differs is shown. A` corrugated section |80 similar in structure and mounting to those previously described is provided to aid in the pulverizing. The lower half of the grinding chamber is not shown since it is the same as that in the other embodiments. In addition to the differences noted, it is further pointed out that conduit |12 does not have a flange such as |56, and instead is secured to housing 25 and plate 28 by Welding as at |18 around the opening |16. Inthe embodiment of Figure 6 as in that of Figure 5, the feed back is low because the feed is tangential in the direction of movement of the hammers which tend to pull the feed into the chamber I6 and thus the conduit |12 gives sufcient baffling effect.

This invention is not intended to be limited to any particular form of rotating elements in the grinder structure. Instead of the hammers 44 carried by discs 42, swinging hammers orother equivalent grinding means may be employed within the scope of the invention. It will also be understood that the invention is not intended to be limited to a structure in which the base has a passageway such as the passageway |'4, through which ground material is drawn oi.

'Ihe advantages of this invention will be apparent from the foregoing description. By locating the driving member in a central position with the grinder on one end, and the fan blade on the other end of the main shaft, a well-balanced structure is obtained. The balance of the structure is also aided by the location of the two bearings between the driving pulley 48 and the fan and grinder respectively. Such a balanced structure has the advantage of decreasing vibration and at the same time decreasing wear Yof the parts.

The various forms of conduit for supplying material to be ground to the grinding chamber, as illustrated in Figures 2 to 6, solve the problem of blow-back and thereby increase the capaciity of the grinder. Whether the blow-back is minimized by admitting material tangentially, as in Figures 5 and 6, or is controlled as in the other embodiments, the capacity of the grinder is increased as compared with the conventional grinding machine, in which material to be ground iscsupplied to the grinding chamber through a simple hopper structure. It will be apparent that the pulverizer disclosed herein is suitable for pulverizing a wide variety of materials, such as, for example sugar and many other like materials.

It is apparent that many widely diierent embodiments of this invention may be made without departing from the spirit and scope thereof, and, therefore, it is not intended to be limited except as indicated in the appended claim.

I claim:

A grinding mill comprising a housing including a cylindrical top portion and providing an internal grinding chamber, a rotating hammer in said chamber, an inlet opening in the top portion of said housing positioned in advance of the vertical center line through the chamber and close to the rotating hammer with relatively small clearance therebetween and through which material to be ground is supplied, an outlet :for ground material, and means for supplying the material to be ground to said inlet opening and including a closed conduit having a relatively short downwardly inclined conduit portion with one end in communication with said inlet opening and extending substantially tangentially with respect to the path of movement of said hammer across the inlet opening and positioned so that material moving from said conduit into the grinding chamber is travelling in substantially the same direction as the rotating hammer, an upstanding conduit portion in communication with the opposite end of said inclined conduit portion and providing an abrupt change of direction for material being fed therethrough, an adjustable feed gate positioned in the downwardly inclined conduit portion for controlling the flow of material therethrough, and a bafe depending from the upper wall of the said downwardly inclined conduit portion and disposed between said feed gate and said inlet opening, said baffle being inclined in the direction of feed of the material through the inclined conduit portion and terminating substantially vertically above and adjacent the lower edge of said inlet opening whereby to close off the upper part of the inclined conduit portion and to trap blown-back material between the upper inclined edge of the baille and the adjacent wall surface of the inclined conduit portion above the inlet opening.

CARL D. PARTEN.

REFERENCES CITED The following references are of record inthe le of this patent:

UNITED STATES PATENTS Number Number Name Date Y Koch June 14, 1927 Hirsch July 26, 1927 Ward Apr. 2, 1929Y Ruprecht et al Apr. 30, 1929 Farner Apr. 1. 1930, Frickey May 20, 1930A Shelton Mar. 31, 1931@ Crago May 30, 1933` Myers May 29, 1934' Sherman July 23, 1935 Frisch May 26, 1936 Barnes Jan. 18, 1938 FOREIGN PATENTS Country Date Great Britain of 1871 Great Britain Nov. 6, 1905 France Jan. 21, 1921 Great Britain May 9, 1935 Italy Apr. 22, 1932 Germany Apr. 20. 1933

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