US2494705A - Hammer mill rotor structure - Google Patents

Description

MM W W5@ M. E. HAMALTQN 49411705 HAMMER MILL ROTDR S'I'RUC'IUREI Filed Feb; 21, 1947 3 Sheetsl-Sheet l M. E. HAMILTON HAMMER MILL ROTOR STRUCTURE am WR m5@ 3 Sheets-Sheet 2 Filed Feb. 2l, 19%7 ATO Wm wg, wm

M. E. HAMILTON 4 Awww Hmmm MILL RoToR STRUCTURE Filed Feb. 21, 1947 :s sheets-sheet 3 INVENTOR. 4 MA TTHEw HAM/z. roN

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rroRNL-vs Patented Jan. 17, 1950 2,494,705 A HAMMER MILL ROTOR STRUCTURE Matthew E. Hamilton, Dearborn,

to Harry Inc., Detroit, Mich., a oorporation oi' Delaware Ferguson,

Mich., assigner Application February 21, 1947, Serial No. 729,925 1 Claim. (Ci. 241-191) l The present invention relates to hammer mills and belt lar high speed power source.

That hammer mills have able success where large quantities of grain must be ground for feed is attributable to the advantages to be derived and which include constantly high operating eiilciency, the production of feed having a great range of ilneness, and the iact that the mill is neither injured by the presence of small` foreign bodies dulled by running empty.

However, standing in the way of increased use oi' hammer mills, particularly on farms of average or small size, is the high initial cost of present day mills and the fact that difficulty is frequently experienced in belt-driving such de vices at an emcient speed from a tractor power takeoir.

Furthermore, conventional mills do not include adequate provision for adjusting and centering the bearings to decrease bearing wear and shaft vibration at high rotative speeds.

it is an object oi' the present invention to provide an improved hammer mill particularly suitable for belt-driving at high speeds from a tractor power takeoi. It is a related object to provide a hammer millin which the bearings are not only constructed and arranged so as to reduce wear and vibration at high milling speeds to a minimum, but in which bearing take-up is eiIected automatically and in which manual adjustment after long. periods of use may be easily and quickly accomplished by the user without disassembling any part of the structure.

It is another object of the invention to provide a hammer mill in which improved means the apparatus.

It is still another object to provide a hammer mill adapted to be belt driven from a tractor power takeoff but which includes means for enabling trouble-free operation at speeds considerably higher than the speeds normally available at the power takeoff pulley, and which is nevertheless simple and inexpensive in construction, eliminating the necessity for precise bearing alinement or other accurate machine work in its manufacture.

achieved lconsiderber of problems,

4 4 of Fig. 3 and revealing tractor. 'I'he use oi' speeds 2 Other objects and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings inwhich:

Figure 1 is a general perspective view of a hammer mill constructed in accordance with my invention and showing the manner in which a sacking attachment may be mounted thereon.

Fig. 2 is a fragmentary perspective view showing the opposite side oi' the hammer mill disclosed in Fig. 1.

Fig. 3 is a side elevation oi.' the body portion of the hammer mili and showing the internal construction in dotted outline.

Fig. 4 is avertical section taken along line particularly the manner in which the bearings are mounted and adjusted. l

While the invention is susceptible of various expressed in the appended claim.

Referring now to Figs. 1 and 2, it will be seen that the hammer mill includes a housing or housing I n is a shaft i2 havinga drum-shaped pulley I4 thereon which is adapted to be belt driven from the power takeoii' of a tractor. The

completed, the grain falls to the bottom oi' the housing Il from whence it is removed by means of a blower i5 (Fig..2) being conveyed upwardly through a conduit l5 and deposited into a hopper or sacking attachment Il which may, if desired, be mounted directly on the mill housing.

It has been found that the common types of feed are most eillciently milled at rotative speeds as high as 3,000-3,200 revolutions per minute or even higher. In order to step up the tractor power takeoil speed into this range. it is necessary to use a pulley Il which is extremely small in diameter as compared to the pulley on. the

ot this order of magnitude is, furthermore. accompanied by a numprimarily of which are guidance Projecting outwardly from the side of the tion, and the bearing adjustmen accenna of the driving belt, increased wear and vibranecessity for frequent and accurate As the discussion proceeds such ditculties are inherently by the disit will be seen that solved in a very eiiicacious manner closed structure.

Turning now to Fig. 3 it will be seen that the mill housing lil includes a lower portion lila and an upper portion lilb hinged thereto about a horizontal hinge le for purposes of access, the two portions lila, ith being kept in normal engagement by any desired type of clamp 2@ located opposite the hinge. The shaft l2 passes through the housing it transversely at about the separation line, being supported on the sidewalls 2t, 2l in bearing assemblies 22, 2li which porting collars or housings 25, 2t. are in turn supported by brackets 2d, 29 which in the present embodiment take the form of angle iron strips extending horizontally along the walls 2G, 2l and fastened thereto by an f suitable means, for example by riveting or welding. in order to maintain a predetermined axial distance between the bearing collars, the latter are rigidly fastened to the brackets 23, 2li by means of throughbolts so, 3|.

Internally, the bearing assemblies 22, 24 will be seen to mount bearings of the conical antifriction type, each having an having an inner race 34 snugly embracing the shaft I2. Corresponding races will be noted to be in opposition, that is, oriented with respect to one another in a manner which prevents axial displacement of the shaft I2. The bearing assemblies further include inwardly extending shielding iianges dirt and other foreign matter into the bearing housing, and the assembly 22 is further shielded by an end cap 3l.

Mounted on the main shaft I2 and extending radially outward therefrom are a series of hammer blades 38, each of which is provided with a hexagonal opening (not shown) to register with the hexagonal surface of a central portion I2a of the shaft l2. Each of such blades includes a is preferably of the reversible blade by through. This arrangement permits of the use of identical hammer assemblies whichmay be interchangeably mounted on the shaft in sets of three assemblies disposed 60 apart.

In accordance with one of the aspectsl of the invention, means are provided for securely clamping the hammer blades 38 on the shaft I2 to insure that they extend radially therefrom and are secured against vibration at high rotaunder conditions of rapid feeding of grain through the mill. To this end cylindrical spacers 42 are employed which have a collar portion 44 spaced from the shaft and the axially presented edges of which are machined parallel. Such spacers 42 are centered by means of a central'web or iiange 45 which is formed integral with the collar 44. The latter construction not only provides a large amount of gripping surface at a point radially removed from the shaft but obviates any misalignment of the hammer blades 38 which may be due to the presence of a burr or local deformation of a. blade in the region of the hexagonal aperture which is punched or otherwise formed therein.

Means are also provided for causing the assembly of hammer blades 38 and spacers 42 to tive speeds and outer race 32 and l 36 for preventing the entry of which is transmitted through one or the innerV bearing races and adiustably applied from outside the mill housing. To resist the clamping force, a flanged collar 48 is fastened by a' pin 41 or any other suitable method to the right-hand end of the shaft I2, preferably on a cylindrical portion 92h of reduced diameter. At the other end of the hammer assembly is a somewhat simliar flanged collar 49 which istelescoped over the cylindrical portion I2c of the shaft I2 and arranged 'in abutting engagement with the inner race t6 of the left-hand bearing. In order to permit a iimited amount of clamping movement of the collar 49, it is internally relieved by an annular groove 50 which is of sufficient radial extent as to clear the hexagonal lands on the portion @2a of the shaft. To apply clamping force to the left-hand edge of the inner race 34,a threaded nut I is used which is screwed on the end of the shaft I2. In the present embodiment the force exerted by the nut 5I is transmitted through the adjacent pulley I4 and a sleeve 52 of small outside diameter, the latter being telescoped over the shaft I2 and abutting the inner bearing race 34. slippage of the pulley I4 is prevented by a key 53, and a similar key may be used in connection with sleeve 52 if found necessary.

With such/structure in mind it will be apparent that advancement of the nut 5I will cause the inner race of the bearing 34 to be moved to the right (as viewed in Fig. 4) `which will cause the collar 49 to be likewise urged to the right, thereby applying clamping pressure serially to the hammer blades 38 and the separating spacer members 42. It is, therefore, a simple matter not only to cause original tightening of the assembled elements, but also to check from time to time that the assembly is still in a tightened condition merely by applying a wrench to the accessibly located nut 5 I It may incidentally b e noted that a single nut 5I not only causes clamping of the internal assembly but in addition provides a means whereby the pulley I4 may be readily removed, if desired, and replaced by one of different diameter.

It has beenfound in the case of hammer mills driven at high speeds that a considerable proportion of the bearing wear and which is encountered is attributable to the fact that the bearings are not accurately alined and to the lack of means for adjusting the bearings from time to time to take up play and to establish a predetermined degree of preloading. In accordance with one of the main features of the invention, therefore, means are provided for constantly insuring proper alinement in spite of inaccurate initial assembly and for further providing for takeup of the bearings both automatically and by means of a single threaded adjustment outside of the mill housing. In accompllshinr the utter and to obtain additional smoothness of operation, resilient cushioning is employed between the outer races and the associated bearing housings.

As shown in the preferred embodiment illustrated in Fig. 4, such resilient cushioning may be accomplished by an annular rubber insert 54, which is interposed between the outer bearing race.32 and an inserted cup member 55 and which is preferably vulcanized to both of them. The insert 54 allows a amount of relative twisting movement to take place between the outer bearing race and the housing which surrounds it when the shaft I2 is secured in place. It'will be be rigidly clamped together by a. clamping forcev 15 apparent, then, that itismerelyw aline shaft vibration the bearing housings 25, 26 approximately during fabrication of the mill, any residual discrepancy or misalinement being compensated for or absorbed by deformation of the rubber cushion. By choosing rubber of the proper physical characteristics, considerable angular deflection may occur without causing any appreciable unbalance of the forces on one side of the bearing as compared to the forces on the side diametrically opposite. The latter construction has reduced the exacting and time consuming alinement of the bearing housings to a quantity production operation in which simple jigs and fixtures may be used and without particular attention being paid to the matter of exact initial alinement. It is also to be noted that the use of the rubber cushions causes the bearings to remain in alinement durof the machine and regardless of the mistreatment to which it may be subjected.

The specific means here used for taking up wear on the bearings and for preloading them is shown at the right-hand portion of Fig. 4, where it will be observed that the inner race 34 of the 22 is snugly telescoped over the the inner bearing race is a nut 58 which is in threaded engagement with the end of the shaft I2 and which may be locked thereto in a desired position of adjustment by means of a cotter key 59. To take up play in the bearing, it is merely necessary to advance the nut 58 along the shaft which results in leftward movement of the inner race 34. The latter shortens the distance between the two inner races and tends to increase the pressure exerted by the inner races against the corresponding outer race. The fact that movement of the adjusting nut 58 is effective simultaneously and equally to change the axial load on both of the bearings will be more clearly seen when it is considered that engagement of the thread tends to draw the shaft I2 to the right with respect to the bearing housing 26 and the wall 2| to which it is rigidly secured. e

In hammer mills not including conical bearings backed by a resilient cushion such as the rubber ring 54 here illustrated, the side play in the bearings increases the vibration of the shaft I2 and greatly accelerates bearing wear. It is necessary in the usual case, therefore, to take up on the bearing frequently, exercising care not to cause excessive preloading which in itself may shorten bearing life. In the present structure, however. it is suflicient to put the rubber cushions under a slight amount of initial preloading, and any subsequent bearing wear is automatically taken up by the expansion of the rubber. It is thus suilicient to take up play in the bearings by adjustment oi.' the nut 58 at long intervals, such adjustment being accomplished very readily by a non-skilled user of the mill without danger that the bearings will be excessively preloaded. The torque which must be applied to the nut 58 to turn it may serve as a measure of the preloading force existing in both of the bearings.

Turning now to the lower portion of Figs. 3 seen that a screen 60 is used for of the particles discharged from the mill, the latter screen being semi-cylindrical in shape and coaxial with the main shaft. Arranged below the screen and centrally in the mill housing is an auxiliary shaft 6I which is journaled in suitable bearings 62, $4. Arranged along the body of the shaft 6I and rotatable therewith is `part of the 1 I a screw conveyor grain into the intake of the blower I 5. The latter includes an impeller 66 which creates an air blast elevating the milled grain through the conduit I6 and into the hopper or sacking attachhousing. open top, as at B2b, providing an air inlet to the lower portion of the housing immediately below the screen.

thus tend to carry it toward the blower.

Power for rotating both the conveyor and the impeller 66 is derived from a sheave 68 which is mounted -at the left-hand end of shaft 6I (as viewed in Fig. 4). coplanar with a driving belt leading from the tractor power takeoff to walk off of the drive pulley in one direction or the other. The latter diiilculty is particularly troublesome with a driven pulley of extremely small diameter used to obtain a high step-up invention contemplates the use of a radially extending iiange which is of an outer diameter considerably greater than that of the pulley I4 and which is generally radially aligned with the inboard end thereof. In the illustrated embodiment such ilange pulley and provide an effective In order to prevent the belt from the outboard end of the pulley I4. hammer mill may be oriented at a so that -any creeping tendency on the belt isinward and against the flange belt guide. slipping off the entire slight angle I claim:

of said bearings having an inwardly facing inner race for cooperating with the respective outer races, the inner race of said rst bearing being telescoped on the shaft and having a shiftable collar adjacent its inner edge arranged to abut said series of hammer blades for clamping the blades against said fixed collar, a nut at the end of the shaft associated with said first bearing for drawing up the inner race thereof tightly against said stacked hammer blades to rigidity 65 which conveys the milled In one of its aspects, therefore,rmy

' meer;

the blade assembly, the inner race of said second bearing being slidabiy telescope@ on said shaft and having a lockable nut for not only retaining the race but for drawing up the race to reduce the spacing between the two inner mees and consequently eect simultaneous and equaiized edjustnmei'.V o the play in said `bearings, the inner -mce of said second bearing having sucient eearance yeative to said xed collar so as to permit maximum makeup for wear of the bearings normally equired d the life thereof.

MATTI-HWY E. 'HMMTON REFERENGIES @FEED The oiiowing reercences are of record im the me or' this patent:

1 STATES PATENTS Nummer Nome Date 1,339,950 Fowler Mey 11, 1920 1,633,318 Gibb@ Jim@ "I, 1927 Name Date Ossing Aug. 21, 1928 Schneider Feb. 4, 1930 Winkler Feb. 11, 1930 Ammon Apr. 1, 1930 ONeill June 17, 1930 Pfeiffer Sept. 1, 1931 Reschke Oct. 2, 1934 Everett Jan. 5, 193'1 Myers May 25, 1937 Ossing Dec. 27, 1938 Alfred Sept. 5, 1939 Everett Nov. 28, 1939 Symons Mar. 5, 1940 McNamara Feb. 11, 1941 Kiamp Mar. 23, 1943 'EORmGN PATENTS Qountry Date (Great Britain June 28, 1923

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