US2543599A

US2543599A - Screen structure for hammer mills

Info

Publication number: US2543599A
Application number: US660256A
Authority: US
Inventors: Carl A Rietz
Original assignee: Rietz Manufacturing Co
Current assignee: Rietz Manufacturing Co
Priority date: 1946-04-06
Filing date: 1946-04-06
Publication date: 1951-02-27
Anticipated expiration: 1968-02-27

Description

Feb. 27, 1951 c. A. RIETZ 2,543,599

SCREEN' smuc'ruaz FOR HAMMER mus Filed April 6, 1946 3 Sheets-Sheet 1 FII'5 L INVENTOR. Car/ 14. R 119/;

ATTORNE V Feb. 27, 1951 c. A. RIETZ 2,543,599

SCREEN STRUCTURE FOR HAMMER MILLS Filed April 6, 1946 3 Shuts-Sheet 2 FIE-'I E A TTORNEY W o 5 2 a w M m a n 3 a "w 3 o 5 f M a 8 I 6 8 bzrmzJ ERLM/ 22 32 2 J 7 54 1 W 5% 1 L a M F F C 7 3 a wv w a 5M 3 7 B I my, 4 ,./(M\\\\ l 23, a I 7 3 A 3 x 9 2% mm 3 w.

Feb; 27, 1951 c. A. RIETZ scam-m STRUCTUREFOR HAMMER ums 3 Sheets-Sheet 3 Filed April 6, 1946 ATTORNEY INVENTOR.

Car/ ,4. E/ef;

Patented Feb. 27, 1951 SCREEN STRUCTURE FOR HAMMER MILLS cm A. mm, San Francisco, Calif., assignor to I Rictz Manufacturing Co., San Francisco, Calif., a corporation of California Application April 6, 1946, Serial No. 660,256

2 Claims. (Cl. 241-88) This invention relates generally to machines for the disintegration of various materials. More specifically it relates to machines of the type wherein hammers carried by a rotor act upon the material to effect disintegration.

An object of the invention is to generally improve the disintegrating efliciency of machines of the above type particularly with respect to the disintegrating action secured by impact of the particles. A feature of the machine which assists in the attainment of this object is the provision of anvil-like impact surfaces of substantial length in the direction of the axis of the machine rotor, and which are faced in a direction opposite to the direction of rotation of the rotor. As will be presently explained the provision branch means makes possible a reverberatory impact action.

A further object of the invention is to gen-' erally improve upon hammer disintegrators of the vertical type such as disclosed in my Patent No. 2,153,590.

Additional objects of the invention will appear from the following description in which the preferred embodiments have been illustrated in detail in conjunction with the accompanying drawing.

Referring to thedrawing- Figure 1 is a side ,elevational view in section illustrating a disintegrating machine incorporating the present invention.

Figure 2 is a section taken along the line 2-2 of Figure l. v

Figure 3 is a sectional detail on an enlarged scale taken along the line 33 of Figure 1.

Figure 4 is a detail illustrating the construction of the top flange of the rotor, with this flange having a provision to prevent undue wear upon the heads of the hammer retaining rods.

Figure 5 is a cross-sectional detail taken along the line 5-5 of Figure 3. p

Figure 6 is a section taken along the line 6-4 of Figure 1.

Figure 7 is an enlarged detail in section illustrating a modified form of screen assembly.

Figure 8 is a side view of the screen assembly as shown in Figure 7, with parts bein broken away.

Figure 9 is a sectional detail like Figure 7 but illustrating another embodiment of the screen assembly.

Figure 10 is a side view of the embodiment shown in Figure 9, with parts being broken away. The machine illustrated in the drawing is a 2 Rietz 2,153,590. Such a machine utilizes a disintegrating rotor mounted upon a vertical axis and provided with a plurality of spaced hammers to afford a zone of operation of substantial vertical extent. A cylindrical shaped screen substantially entirely embraces the zone of operation and is carried by the main housing or frame of the machine. The housing is formed 7 to provide an inlet opening at the upper end of the screen whereby material supplied through this opening is fed to the'zone of operation. The housing also provides an annular outlet opening at the lower end of the screen for de livering material which is passed by the screen as a result of the disintegrating action of the hammers. Disintegrating machines of this type afford a relatively high capacity and have been found well suited to the disintegration of a wide variety of materials.

Referring to Figures 1 to 5 inclusive of the tical shaft [3. The upper end of this shaft is supported from a suitable thrust hearing it and is coupled to a suitable electric motor IE, or provided with other suitable means for driving the same. The opening or passage ll of the housing serves to supply material to be disintegrated to the zone of operation of the rotor. The shaft can be provided with breaker blades ii to generally break up coarse material before feeding the same to the rotor.

The rotor is surrounded by the substantially cylindrical shaped screen assembly I8, and as will be presently explained material acted upon by the disintegrating hammers is forced through this screen assembly for ultimate discharge. A skirting IQ of a type to be presently explained generally surrounds the screen assembly l8, and the space 2| immediately surrounding the screen communicates with the annular discharge opening 22 formed in the housing base 23. In actual installations the machine is mounted in such a fashion that the material discharging downwardly through opening 22 is received by a suitable hopper or conveying/"beans which underlies the machine.

The rotor assembly l2 consists of a lower annular flange 26 (Figure 1) which is accommodated on shaft l3, together with a plurality of overlying stacked flanges 21 and a top flange 28. The disintegrating hammers 29 are each provertical type hammer mill of the type shown in vided with inner arcuate portions 3| (Figure 2) amasea hammers designated 38, are preferably'iof special I construction for the purpose of aiding in downward movement of material being disintegrated. Thus these hammers have head portions 36a and shank portions 36b which connect the head portions with the arcuate anchoringjportions 3|. Portions 36b are disposed at an inclination to the horizontal as shown in Figure 5, assuming rotation from right to left as indicated in this figure. They act in effect as propelling means tending to urge the material downwardly into and through the zone of disintegration. In addition portions 361) tend to cut up material being fed downwardly, and in general they tend to prevent bulky material from riding upon the top of the rotor assembly, rather than feeding downwardly as desired.

To prevent undue wear upon the nuts or heads 34, of the anchoring rods and upper face of the top flange 28 is provided with ribs 31. These ribsare located in advance of the heads 34, and they haveinclined faces 38 tending to deflect the material to prevent direct impact contact with the heads 84.

The lower end of the rotor shaft is shown journaled as by means of ball bearing assembly 4! to the annular casting 42. This casting is secured to the base of the housing by screws 43, and it affords an annular passage 4d underlying the zone of operation of the rotor. It has been found desirable to form passage 44 with divergent inner and outer walls as illustrated (Figure 1), because such construction has been found to prevent clogging when the machine is operated to provide a secondary discharge in the manner disclosed in my Patent 2,325,426. When such a secondary discharge is not desired the passage 44. is suitably blocked off by application of a closure plate or screen.

Previous reference has been made to the skirting means i9 surrounding the exterior oi. the screen assembly it. As shown in Figure 2 the base of the machine connects integrally with the upper part of the housing by the

vertical struts

46, 41. The outer faces of these struts conform to a cylindrical surface, and are engaged by the

sheet metal sections

48, 49 and 50. Sections 48 and 45 can be integrally attached as illustrated, and their vertical edges 52 are brought together in overlapping relation to the

vertical edges

53, 54 of the section 50. .Suitable means such as the hinged bolts 55 are employed for releasably retaining the sections together.

The

wall portions

56, 51, 58 of

sections

48, 49, 50 are inclined outwardly (Figures 1, 2) where by material which contacts their inner faces may be more readily dislodged, as will be presently explained. Such outward inclination may be utilized to provide openings to facilitate introduction of a tool or rake to dislodge accumulated material, or if desired such openings may be closed by suitable means.

The screen assembly illustrated particularly in Figure 3 consists of two semi-cylindrical screen sections iii, the adjacent vertical edges of which are attached to the angle irons 82. Normally these angle irons are held together by a plurality of c clamps 63, 64, and one or more of the clamps 64 can be provided with extension 4 88 to abut the vertical stud 41 in order to prevent rotation of the screen. The screen in this instance is formed of sheet metal with opening 6'! of suitable diameter to pass the size of disintegrated material desired.

Upon the inner face of the screen but disposed in such a manner as to not interfere with rotation of the hammers, I provide {means tending to form a plurality of anvil-like impact faces. In this particular embodiment such anvil-like faces are formed by a plurality of vertically extending strips 68 which are distributed circumferentially about the rotor and attached to the screen 6!. Assuming rotation in a counterclockwise direction as viewed in Figure 3, the faces 68a of strips 68 are faced opposite to the direction of rotation, and afford a reverberatory action in connection with the impacting and disintegration of material, in a manner which will be presently explained in greater detail.

In the distintegration of certain types of iibrous material, as for example wood pulp fibre being processed, an objectionable dehydration of the cell structure occurs to the detriment of the finished product. It has been found possible to prevent such dehydration by forcibly injecting water into the zone of operation of the machine. Thus a plurality of nozzles H are provided above the rotor and discharge downwardly through the opening l1. These nozzles are connected to a suitable source of water or water solution under pressure. In addition a plurality of nozzles 12 are provided about the screen assembly, and these nozzes are arranged to forcibly discharge coarse spays of water against the sides of the screen. The water is applied to the screen with such force that a considerable amount of the water passes through the openings of the screen into the zone of operation. In this manner water is injected into substantially all parts of the zone of operation of the rotor, and therefore fine droplets or a mist of added water is provided in such a manner as to prevent dehydration of the cell structure of the fibre.

In the treatment of certain types of material such as peanut meal, it has been found that there is a tendency for this material to accumulate and clog the outlet opening 22. To effect dislodgment of any such accumulations without interfering with continued operation of the machine, I provide a plurality of agitating rods or rakes 13. These rods extend loosely through the openings l4, and their upper ends are provided with suitable handles 16. The rods are a suitable length to extend downwardly through the annular openin 22. To dislodge any accumulation of material in opening 22, the operator grasps handle I6 and then by imparting movement to the rod the undesired accumulations of material are agitated and caused to be ejected.

Operation of the machine described above can be reviewed as follows: The machine is placed in operation with the rotor turning at a suitable speed, such as speeds of the order of 2700 R. P. M. or more. The material to be distintegrated is supplied through the hopper II and passes into the zone of operation through opening ll. As the material enters the zone of operation of the rotor it is engaged by the upper most hammers 36 and by virtue of the inclined hammer portions 36b, there is a. downward feeding action. Within the zone of operation the material is repeatedly impacted by the forward faces of the hammers, and particles propelled from the hammers by virtue of such impacts strike and rebound from the inner face of the screen, and particularly they strike and rebound from the anvil-like faces 56a. of the strips 68. Material rebounding from the faces 68a is again struck by the hammers, and therefore there is in effect a continual impacting of the material back and forth between the hammers and the faces 60a, to afford what can be termed a reverberatory impact action. By virtue of such action highly efficient disintegration is provided, thus making possible high capacity without wasteful utilization of power to produce the desired degree of distintegration. when the material has been reduced by impacts to poper fineness it is passed by the apertures in screen GI, and then falls downwardly through the annular discharge opening 22. When fibrous material is being handled and where it is desired to prevent dehydration of the cellular structure, water is supplied to the nozzles ll, 12 whereby added droplets of water are forcibly introduced into the zone of operation to intimately associate such water with the material being distintegrated. In this manner it has been found possible to prevent cellular dehydration, thus affording a relatively high quality distintegrated product suitable for further processing. As an example of fibrous material which can be treated in this manner reference can be made to various types of wood fibre which can be distintegrated to produce various types of paper stock, without the objectionable dehydration of the cellular structure experienced with ordinary hammer types of mills.

In handling materials which are relatively adherent and tend to conglomerate together when disintegrated, like peanut meals, the

inclined curtain walls

56, 51, 58 tend to be self defecating and facilitate gravity and manual dislodgement of any accumulated material.

Should any part of the opening 22 tend to become clogged by accumulations of disintegrated material, the opening can be readily cleared by manual use of the rake 13.

The reverberatory effect previously described can be produced by means other than that incorporated in the foregoing embodiment. Thus as shown in Figures 7 and 8, the screen assembly 8| consists of a relatively fragile sizing screen 82, an exterior relatively strong backing screen 83 having relatively coarse openings, and an inner covering plate 84 provided in this instance with staggered slots 86. These slots are disposed to register with certain of the openings in the backing screen 83. The vertically extending faces 81 afforded by the slots 86 form anvil-like surfaces for impacting the material being disintegrated in substantially the same manner as the forward faces of the strips 68 of the first described embodiment.

In the embodiment of Figures 9 and 10 the assembly 88 consists of a relatively fine and fragile sizing screen 89, an outer backing screen 9| having relatively coarse perforations, and an inner plate-like member 92 provided with square openings 93. These openings provide vertically extending anvil-like surfaces 94 for impacting the material being disintegrated.

Subject matter disclosed but not claimed herein is disclosed and claimed in my co-pending application Serial No. 166,277, filed June 5, 1950.

I claim:

1. In a disintegrator, a rotor mounted upon a vertical axis and provided with a plurality of circumferentially and vertically spaced hammers to thereby form a zone of operation of substantial vertical extent, a generally cylindrical shaped sizing screen substantially entirely embracing the zone of operation, a housing serving to support the rotor and the screen, the housing providing an inlet opening at the upper end of the screen for feeding material to be disintegrated to the zone of operation, and a rigid plate-like member extending over the inner face of the screen, said member being provided with a plurality of openings distributed over the entire area of the screen, each of said openings being dimensioned whereby said plate-like member provides upstanding anvil-like impact surfaces extending generally parallel to the axis of the rotor for a substantial vertical distance and faced in a direction against the direction of rotation of the rotor, said openings being staggered in a vertical direction whereby the vertical length of each impact surface overlaps the vertical length of an adjacent surface.

2. In a disintegrator, a rotor mounted upon a vertical axisand provided with a plurality of circumferentially and radially spaced hammers to thereby form a zone of operation of substantial vertical extent, a generally cylindrical shaped screen substantially entirely embracing the zone of operation, a housing serving to support the rotor and the screen, the housing providing an inlet opening at the upper end of the screen for feeding material to be disintegrated to the zone of operation, and a rigid plate-like member extending over the inner face of the screen, said member being provided with a plurality of openings distributed over the entire area of the screen, each of said openings being dimensioned whereby said plate-like member provides upstanding anvil-like impact surfaces extending generally parallel to the axis of the rotor and of substantial vertical extent and faced in a direction against the direction of rotation of the rotor, adjacent circumferentially spaced openings being at different elevations whereby the vertical extent of each opening overlaps the vertical extent of an adjacent opening.

CARL A. RIETZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 5,936 Moore June 30, 1874 Re. 8,258 Meech May 28, 1878 40,217 Sellers Oct. 6, 1863 249,793 Paden Nov. 22, 1881 257,841 Bellinger May 16, 1882 265,957 Gates 1 Oct. 17, 1882 297,755 Case Apr. 29, 1884 306,275 Moller Oct. 7, 1884 399,518 Good "9..---- Mar. 12, 1889 440,537 Boyd Nov. 11, 1890 665,935 Rudolph Jan. 15, 1901 1,018,440 Paul Feb. 27, 1912 1,422,761 Hartman July 11, 1922 1,574,436 Martin Feb. 23, 1926 1,767,921 Gately June 24, 1930 1,977,771 McMahan Oct. 23, 1934 2,153,590 'Rietz Apr. 11, 1939 4 2,199,729 Peterson May 7, 1940 2,241,848 Eckart May 13, 1941 2,273,405 Hoehn Feb. 17, 1942 FOREIGN PATENTS Number Country Date 539,524 Great Britain Sept. 15, 1941