US2888211A - Hammer mill - Google Patents

Description

y 19x59 c. R. MYERS ETAL 2 ,888,211

HAMMER MILL I Filed April 25, 1955 3'SheefiQ-Sheot l CLARENCE ROBERT MYERS HAROLD M. STEVENS JOHN B. MYERS w) Arm //v VEN 70/1 5 y 26, 1959 c. R. MYERS ETALN 2,888,211

HAMMER MILL v Filed April 25, 1955 s Shuts-Shoot 2 CLARENCE ROBERT MYERS HAROLD. M. STEVENS JOHN B. MYERS E Y%W, W 1 wzdwv May 26, 19.59 c. R IMYERs ETTAL HAMMER MILL Filed April 25. 1955 .www v Qmw Qmw mmw vs 5 HEY N WW My M Q fl k u VI4 1 4 M M A \mmm L 3 L iv m N m m C NW WW United States Patent HAMMER MILL "Clarence Robert Myers, Harold W. Stevens,.and John B. Myers, Streator, Ill., assignors to The Myers Sherman Company, Streator, 111., a corporation of Illinois Application April 25, 1955, Serial No. 503,734.

4 Claims. (Cl. 241-37) This invention relates to hammer mills and particularly to improved feed and control. mechanisms for suspension type hammer mills.

The improvement of the present invention relates to hammer mills of the type in which the material to be ground is fed substantially tangentially to a set of rotating and pivotal hammers past a grinding plate. As the material drops from the. grinding plate it falls into the path of the rotating hammers which are rotating in. a direction such that. the path of. travel adjacent the. grinding plate is in the same direction as the movement of the. material being ground. The, hammers. initially grind. the. material while it. is. suspended. in mid air andaccordingly this. type of hammer mill is referred to. as. a suspension. type hammer mill. The ground material, is, carried. by the. hammers downwardly and across. a screen. If. the material has been ground tothe desired degree of fineness, it passes through the screen and is carried by a pneumatic conveying system to a collection. point where it is stored, put into bags, or otherwise disposed of;

.111 machines of this type used heretofore, it has been difficult to regulate the feed past the grinding plate in such a manner as to operate the prime mover for the hammers at its optimum rated capacity and still mai ntain the desired fineness of grinding. If the hammer mill was run at its optimum capacity, the degree of grinding was not proper and, vice versa, if the desired degree of grinding was obtained, the hammer mill was not operating at optimum efficiency. It further was found. in these prior machines that it was necessary to change the screens through which the ground material passed on its way to the pneumatic conveying system for each desired degree of final fineness ofthe ground product. In grinding feed materials for livestock, it is desired that certain of the feed materials be ground to a fineness such that they may pass through a inch screen whereas other material may only be ground to a fineness such that it willpass through a 1% inch screen. Since the hammer mill itself often is placed in the basement of the mill and thefeed, bagging and control mechanism are positioned on the first floor of. the mill, it has been inconvenient and time consuming to change the screen in the hammer mill when changing the. type, of material being ground.

The operation of the pneumatic conveying; systems in. prior suspension hammer mills has also been hampered by lack of sufficient air. supply passing down past the hammers. In those structures in which. additional air supply past thehammers has beensupplied, the additional air supply carried unground material. withit around the;

grinding plate so thatthe material was of necessity ground. against the screen or other parts of the hammer mill instead of 7 against the grinding plate or by suspension grinding.

Also in prior hammer mills of the type setforth, the control for increasing or decreasing the feed to the hammer mill has been positioned at the hammer mill which as has been explained above is oftenpositioned' away from the feed and baggingstations which may been-different- Z floors. Furthermore, the control of the feed has been manually operated and often is changed only with difficulty during actual grinding.

Accordingly, it is an important object of the present invention to provide an improved hammer mill ofv the suspension grinding type and particularly improved feed and control mechanisms therefor.

Still another object of the present invention is to provide an improved feed mechanism for hammer mills of the type set forth in which the grinding plate forms a part of the major feed control mechanism, the grinding plate being adjustable from a substantially fully closed to a fully opened, position; more specifically, it is an important object of the invention to provide a feed control mechanism of the type set, forth. which is electrically op.- erated from a remote control station and is easily changed and operated during the grinding operation.

Yet another object of the present invention is to pro vide in a hammer mill of the type set forth a feed control whereby the position of. the grinding plate with respect to the ends of the hammers in operation is adjustable whereby to achieve varying degrees of fineness of grinding; in connection with this object it is more particularly an object to provide an electrically controlled mechanism for adjusting the degree of fineness of grinding in hammer mills of the type set forth, the degree of fineness. being indicated and controlled, at a point remote from the hammer mill and being fully adjustable during the grinding operation. 7

Still another object of the invention is to provide in hammer mills of the type -set forth provided. with the feed control mechanisms specified limit means to prevent injury-to the hammer mill or the feed control mechanism when approaching the fully opened or the fully closed positions of the feed control mechanism.

Yet another object of the present invention is to pro vide in. hammer mills of the type set forth an auxiliary supply of air for the pneumatic conveying systems used in conjunction therewith which supplies adequate amounts of air for operation of the conveying system in all positions of the feedcontrol' mechanism, the supply of air being arranged so that itv does not interfere with proper passage of. the: material to. be ground past the grinding plate.

Still another object of. the invention is' to provide in hammer mills of the type set forth an improved control mechanism. for the feed whereby the rate: of feed is adjusted in coordination with the. fineness of feed so that maximum rated. output of the prime-mover for the hamm r. mill1is. utilized duringithe. grinding operation, means being provided. in addition to indicate when the prime mover for the hammer mill is operating at optimum eificiency.

A further object of the invention is to provide an improved suspension type hammer; mill of the type set forth in which the rate of feed of the material to be ground and the space between the. grinding plate and the tips of the hammers in operation can be adjusted interdependent- 1y so that all the. material to be ground is ground to the desired fineness. in one passage around the hammer miil from. the-feedv input. to the. screen leading to the output? from. the hammer mill to provide substantially one. pass grinding thereby making it. unnecessary to change grinding screens when making; large. changes in the fineness of the ground material.

A still further object ofthe invention, is to provide a hammer mill. which assures a granular grind using posi'-- tive suspension. grindingin. which hay and other rough-- ages are ground uniformly Without variancein particle;- size and without thev formation of strings.

These and other objects and advantages. will be better. understood from the following description when taken in conjunction with the accompanying drawings. In the drawings wherein like reference numerals have been utilized to designate like parts throughout:

Figure l is a dia'grammatical view in vertical section through a mill incorporating a hammer mill made in accordance with and embodying the principles of the present invention;

Figure 2 is an enlarged view partly in section of the installation of Figure 1 substantially as seen in the direction of the arrows along the line 2-2 of Figure 1;

Figure 3 is a further enlarged view in vertical section with certain parts broken away through the hammer mill of Figure 2 substantially as seen in the direction of the arrows along the line 33 of Figure 2;

Figure 4 is a rear elevational view with certain parts broken away of the hammer mill shown in Figure 3;

Figure 5 is an enlarged view in vertical section substantially as seen in the direction of the arrows along the line 55 of Figure 4;

Figure 6 is a view in vertical section substantially as seen in the direction of the arrows along the line 6--6 of Figure 5; and

Figure 7 is a view in horizontal section substantially as seen in the direction of the arrows along the line 77 of Figure 6.

Referring to Figure 1 of the drawings, there is shown a typical grinding mill installation utilizing a hammer mill generally designated by the numeral 10 made in accordance with and incorporating the principles of the present invention. Hammer mill 1!) is shown installed upon a basement floor 12 and is provided with a chute 14 leading upwardly to a dump sink 16 communicating with an aperture 18 which is preferably at ground level and outside of the building wall 20. Preferably the controls for hammer mill 10 are positioned above the work floor 22 which is substantially at the same elevation as the ground. It will be seen that by this arrangement the material to be ground can be dumped through opening 18 into the sink 16 from ground level and that the operation of mill 10 can be controlled from the work floor 22 which is also at ground level.

It is to be understood that hammer mill 10 can be used in cooperation with other systems for storing and conveying the material to be ground thereto. For example, instead of the dump sink and chute illustrated, a chute for hay and the like can be used in combination with a drag for grain, ear corn, and the like. Alternatively, a hopper and feeder can be used which discharge onto a mill feed table connecting with the hammer mill 10 or a fixed chute can be used to feed material onto a mill feed table cooperating with hammer mill l0. Accordingly, it is to be understood that the present invention is not limited to the specific mill installation shown in the drawings.

The hammer mill l0 and the source of motive power therefor are mounted upon a hollow frame 24. More specifically, a pair of angle irons 26 and 28 (see Figure 3) are riveted as by rivets 30 to flanges on the frame 24 and angle irons 26 and 28 are in turn welded as at 32 to a collector 34 which forms part of the support framework for hammer mill 10 and also serves to collect the ground material which has passed through the hammer mill 10. Collector 34 is substantially rectangular in plan section and in transverse section tapers downwardly to form a chute 36 which collects the ground material and deposits it into the inlet to a pipe 38 (see Figure 2). Pipe 38 is part of a pneumatic conveying system which conveys the ground material upwardly to a point where it is collected and separated from the mass of conveying air for delivery to an output point. Preferably the outlet for the ground material from the pneumatic conveying system is at a point remote from the hammer mill 10 and usually is above the work floor 22. The outlet for the ground material may be a bagger or a pipe leading to a storage facility or to a truck for transportation to a storage facility. Further description of the pneumatic conveying system will be given later.

Formed on the upper edges of collector 34 are inturned flanges 4t and 42 which support a screen 44 of the usual type employed in hammer mills. Screen 44 is part-circular in shape and is formed on a radius such that it conforms to the path which hammers in the hammer mill follow during the grinding operation. A pair of outturned flanges 46 and 48 are provided on the upper edges of screen 44 to overlie collector flanges 40 and 42 whereby to support the screen 44 thereon. Screen 44 extends substantially the entire length of collector 34.

Mounted above collector 34 is a movable upper harnmer mill housing 50 which rests upon and is supported by the collector 34. More specifically, housing 50 has a length substantially equal to the length of collector 34 but is slightly narrower as is seen in Figure 3 at the point of which it rests upon collector 34 and screen 44. The lower end of housing 50 is provided with a pair of outturned flanges 52 and 54 which rest upon flanges 46 and 48, respectively of screen 44 and serve to hold screen 44 in position upon flanges 40 and 42 of collector 34.

Housing 50 also includes a substantially vertically disposed rear wall 56 which at its upper end is curved to provide a guide wall or baflle 58 which serves to guide material to be ground to the hammers at certain positions of the feed control mechanism. The ends of housing 50 are closed by two side plates 60 which are suitably secured to rear wall 56 and are shaped to conform to baflle 58 at the upper ends thereof. A short baffie or forward wall 62 is also provided, wall 62 being curved concentric with the path of travel of the ends of the hammers andspaced outwardly therefrom.

The entire housing 50 is mounted to swing forwardly or to the left as viewed in Figure 3. More specifically, a pair of brackets 64 is mounted upon collector 34 on the front side thereof and support a shaft 66. A pair of hinges 68 is fixedly attached to the side plates 60 and the hinges 68 are pivotal about shaft 66. In order to hold housing 50 in operative position upon collector 34, an adjustable clamp is provided. The clamp includes an arm 70 fixedly attached to rear wall 56 and carrying thereon an adjustable stop 72. Engaging the upper end of stop 72 is an eccentric cam surface 74 formed integral with a handle 76 and pivotal about a pin 78. Pin 78 is carried by a pair of links 80 which in turn are pivoted on collector 34 about a pin 82. With the handle 76 in the position shown in Figures 3 and 4, cam surfaces 74 serve to lock the housing 50 in operative position upon collector 34. Movement of handle 76 in a clockwise direction as viewed in Figure 3 disengages cam surfaces 74 from stops 72 and permits the entire housing 50 to be pivoted about shaft 66 to the left and in a counterclockwise direction as viewed in Figure 3. When housing 50 is in the upper or open position, screen 44 can be readily removed and replaced. A pair of blocks 84 and 86 are carried by rear wall 56 and front wall 62, respectively, and aid in holding screen 44 in position when housing 50 is closed.

A pair of brackets 88 are mounted on the ends of collector 34 and support a pair of pillow block bearings 90 which are bolted thereto as by bolts 92 and rotatably support the main shaft 94. Main shaft 94 carries a plurality of plates 96 u on which are mounted hammers 98 by means of rods 100. Hammers 98 are free to rotate about rods 100 and with respect to plates 96. Accordingly, hammers 98 are in the position illustrated in Figure 3 only when shaft 94 is being turned at a relatively high rate. With hammers 98 in the position shown in as ista Figure. 3,, the hammers serve. to grind. and. comminutematerial that falls in the. path thereof;v

Motive power to rotate. shaft 94 is; derived form. an. electrical motor 102 (see Figure 2) which is mounted upon the frame 24 by a plurality of bolts 104. Motor. 102 has been illustrated as a three phase motor powered from a plurality of lines 106 which connect through. a control and starter box 108 to a suitable source of. elec-v trical power. Operation of.motor 1(l2. is vcontrolledhy handle 110 on control box 108 and the power consumed by motor 102 is indicated on a meter 112.

The output of motor 102. appears on a shaft 114 which is connected by a universal joint 116 to the main shaft. 94. A shield 118 extends around the universal joint 116 to prevent injury to the operator by contact therewith. Also positionedaround the portion ofv shaft 94 outside of. the hammer mill proper, is a brake 120 operable by a handle 122 so that rotation of shaft 94 and associated parts can be stopped as desired.

Shaft 94 also extends outwardly from the left. hand side of the hammer mill as viewed in Figure 2 and drives a fan 124 which moves the airstream in the pneumatic conveying system. The pipe 38 described above carries the ground material from the hammer. mill to fan 124 and fan 124 discharges into a delivery pipe. 126 which carries the air stream and the ground materialsuspended therein to the point of .-disposal.

Material to be ground is fed downchute 14 to. a hopper 128 which. feeds; directly into housing .50. Referring more. Particularly to Figure 3, it. will be seenv that hopper 1.28v includes a bottom wall 139 which extends downwardly to the upper edge of frontwall 62; Formed integral with bottom wall 130 is a pair of, side walls 132 and 134 which are joined by a top wall 136. Extend.- ing, downwardly from side walls 134 adjacent the lower edge of, bottom, wall 130 is a pair of ears 138 which receive a rod 140 therethrough. Rod. 140 extends, through a hollow pipe 142 which is suitably secured as by welding, to a curved plate 144. which is adjustably positioned upon front wall 62. More specifically, front wall 62 has welded thereto a stud 146 which extends through an elongated aperture in plate 144. A nut 148 threadedly engages stud 146 to.hold plate 144 in adjusted position upon front wall 62. In this manner the lower or discharge edge of bottom wall 130 canbe adjustedinposition with respect to theupper. edge of. front wall 62.

Additional means is provided toconnect hopper128. to housing 50 in, the form of a plurality ofangle. iron pieces which are bolted together. More specifically, .a pair of angle iron. members 150 are. secured to the side walls 60 as by welding and an angle iron member. 152 connecting with angle iron members, 10is welded. along the: forward edge-of guide wallv 58. A. flange 154 which cooperates with angle iron members 150-152 is suitably secured to hopper 128 bymeans of an attachment, meme her 156 which is secured to hopper 128 by a plurality of nuts and bolts 160. A plurality of bolts 162 interconnect flange- 154 with the abutting flanges on angle iron members 150 and 152.

Since the hopper 128 is fixedly attached to housing 50, it is necessary that hopper 128 pivot about shaft 66 with housing 50. To this end, a pair of arms 164 is provided, one end of the. arms 164 beingpivoted'. about shaft 66 and the other ends being connected by pins 166 to flanges 168. that are secured as bywelding to hopper 128. By this. construction. hopper 1 28 pivots about shaft 66. with housing 541.

v In order to achieve suspension grinding in the hammer mill 10, a grinding plate 176 is provided adjacent the hammers 93 and in the path of the material to be ground descending from hopper 128. Plate 170. extends substantially the entire length ofhousing 50 and. extends substantially vertically and. parallel to the rear Wall 56,. A threaded shaft 172 is. fixedly attached as by. welding, to a; mounting plate. 174 which is. in'turnv secured to. the

grinding. Plate (see Figure-5). Also mounted. upon plates 170' and 174 is'acurvedbaflie 176"which extends upwardly, above grinding, plate. 170 andis, curved" sub stantially to conform to the shape of the. guide portion 58 of housing 50.- Bafiie 1.7'6,v plate 174' andl'grinding plate 170 are interconnected by a plurality of, studs. 178. aflixed to bafiie 176 and extending through alignedapefi: tures in plates .170 and 174' and cooperatinglwithv nuts 180.

In orderto obtain control overthe rate. of feed "of material to be ground from hopper 128;, the position of baffie 176 and. grinding plate 170 with respect to the discharge end of hopper 128. adjustable to provide a feed'inlet for material". to be ground which. is, adjustable in size; In addition, the distance off the lower endof grinding plate 176 from, the tips or hammers 98 or the arc 'oflthe throw of the hammers isladjustable'whereby to obtain adjustability in, the degree of fineness of. grind of'the hammer mill. t 4 Y I To these ends a pair ofarcuate tracks is provided by cuttingfarcuate. openings of the desired shape. in side plates 60. Welded to the edges of. the arcuate. openings are track members 182' and 184 which are, U-shaped in cross section and conform to the shape of the arcuate openings. Suitably secured as by welding. to therear. of grindingplate 170 is a hollow pipe 186'which receives therethrough a shaft 188. The ends of shaft' 188' ex? tend outwardly beyond side plates 60 and into track members .182 and 184' to be. guided thereby. As, may be seen in Figure 3,, the track. members 182 -184 extend. from rear wallf56 to, the upper edge of. front wall .62..

Movement. of. grinding plate 1.7.0 alongfltrack, mem; bers 182-184,is accomplished'and' controlledby a mocha.- nism which will, newv be. described; Referring, to. Figure 5,] it will be seen that the threaded, shaft' '172- extends through an aperture 190 in rear wall 56'and engages a nut sleeve 192' which has the left handIend thereof. threaded whereby threa'd'edly to engage shaft 172, and the right hand thereof formed smooth to provide a' guide for shaft 172. Nutsleeve 192 isi'n turn rotatablyreceived by a bearing block 194. A first bearing. washer 196' is provided between bearing block. 194 and 'a'shoulder 198 formed on nut sleeve 1'92 and. a second, bearing washer 26.6 bears against the opposite face of bearing block 194 between bearing block 194 and a bevel. gear 202 which is fixed to nut .sleeve 192 by a'set"screw"204.. Bythe above described arrangement nut' sleeve. 192' can bero-g tated with respect to hearing block. 194. andshaft 172 whereby to move shaft 172. andatta'ched parts including grinding plate 170 toward andfaway' from bearingblo'ck 194 and rear wall 56'.

Power for driving bevel'gear 202' Wherebytdmove shaft172 and grinding plate 170 is derived from an electric motor 266 (see Figures 1. to 4);, Motor. 206,]dr1ives a gear reducing mechanism 208; the output of" which drives a. universal connection. 210. Universal connection 210 in turn drives a shaft 212 (see Figure. 5) which is journaled in a plate 214 fixedly secured to hearing block 194 as by welding at point 216. Motor 206 and gear reducing mechanism 208 are likewise mounted. upon plate 214 by ahousing member 218,.

Shaft 212 is heldin proper position upon plate 214 by means of a collar 220 fixedly-attachedv to shaft 212 by a set screw222. A washer 224 ispositioned, beneath plate 214 around shaft 212 andabove a" second. bevel,

' gear 226 which meshes with bevel gear 2il2'"desoribe'd above. B'evelgear 226 is keyed to sh'aft'212 and is secured, thereto by a screw 228 and 'a washer 230. By this described arrangement the electric motor 206 serves to drive the. bevel gears 2412 and 226 which in. turn rotate the nut sleeve. 192. Rotation of nut sleeve 192 within bearing block 194 moves threaded shaft 172 to the right or to the left as viewed in. Figure 5' depending upon the" direction of rotation of drive motor 206'. Movement of shaft 172 to the leftlor'to. therightas. viewedin.

. 7 carries with it the grinding plate 170 and attached parts. Since the grinding plate 170 moves along an arcuate path in traveling from rear wall 76 toward the entrance to chute 128, it is necessary that shaft 172 and attached parts be capable of moving to accommodate this motion. To this end bearing block 194 is formed and mounted so that it can pivot about a horizontal axis as viewed in Figures 5 and 6. More specifically, bearing block 194 is provided with a pair of pivot ears 232 and 234 which are formed integral therewith and extend laterally therefrom. Ear 232 is received in an aperture in a triangular flange 236 and pivot ear 234 is similarly received in an aperture in a triangular flange 233. Flange 236 has formed integral therewith and at right angles thereto a flange 240. Flange 240 is securely fastened as by bolts 242 and nuts 244 to a plate 246 which is U-shaped in vertical section as seen in Figure 5 and has two rearwardly extending legs 248 and 250 which are suitably secured as by welding to rear wall 56. Flange 238 is provided with a right angular integral flange 252 which is secured by bolts 254 and nuts 256 to plate 246. In order to provide lubrication between nut sleeve 192 and bearing block 194, the pivot ears 232 and 234 are provided with lubrication fittings 258 which communicate with lubricating channels 260 formed in bearing block 194. It is desirable to make the mounting for hearing block 194 substantially air tight and to provide adjustable means which can be tightened about bearing block 194 as the various parts become worn. To this end the upper and lower sides of bearing block 194 are rounded as at 262 and264 to cooperate with the edges of plate 246 through which bearing block 194 extends. Furthermore, there is attached to plate 246 above bearing block 194 a sealing member 266 having a sealing flange 268 bearing against the upper surface 262 of bearing block 194. A bolt 268 extends through an elongated aperture 270 in sealing member 266 and threadedly engages plate 248 whereby adjustably to position sealing flange 268 on bearing block 194.

The rounded surface 264 on bearing block 194 rests upon a sealing flange 272 which is mounted upon plate 246 by'a bolt 274 passing through an elongated aperture 276 in an attachment flange 278. In this manner the sealing flange 272 can be adjusted against the curved surface. 26-4 on hearing block 194.

In order further to provide for air tightness around the mounting for hearing block 194, the edges of plate 246 are closed by side plates 280 and 282 which are welded at their forward ends to rear plate 56 and at their rear ends to plate 246. The shape of plates 280 and 282 is such as completely to enclose the area bounded by rear wall 56, plate 246 and flanges 248-250. From the above described construction it will be seen that motor 205 and the mechanism interconnecting motor 206 and nut sleeve 192 are all mounted upon bearing block 194 whereby to move with grinding plate 170. Referring particularly to Figure 3, the precise configuration'of track members 182 and 184 will be described in detail. The right hand end 284 of track 184 as seen in Figure 3 is substantially horizontal. With grinding plate 170 positioned as shown in solid lines in this figure, the maximum rate of feed of material to be ground from hopper 128 to the hammers 98 is obtained. The lower edge of grinding plate 170 is spaced sufficiently far from theends of hammers 98 and the arc of the throw thereof so that a minimum of suspension grinding is obtained.

. The left hand end of track portion 284 joins the curved portion of track 184 at a point 286 and track 184 is curved from point 286 to the left hand thereof to provide a curved section 288. The left hand end 290 of curved track portion 288 is positioned such that the lower edge of grinding plate 170 is positioned approximately means 8 /8 inch away from the arc of the throw of the ends of hammers 98 when the hammers 98 are in operative position as shown in Figure 3. Curved portion 288 of track 184 gradually curves outwardly away from the arc of throw of the ends of hammers 98 so that the spacing between the lower edge of grinding plate increases from the distance of A; inch at point 290 to a distance of approximately /2 inch at point 236 on track 184. By this construction the fineness of grind of the material fed into the hammers 98 can be adjusted by adjusting the position of plate 17 0 along track 184.

Grinding plate 170 together with baflle 176 forms a control of the size of the feed inlet for the feed of material to be ground from hopper 128 into the hammers 98. With baffle 176 and feed plate 170 positioned as shown by dotted lines in Figure 3, the feed inlet is substantially closed and feed of the material to be ground to hammers 98 is effectively stopped. As feed plate 170 and baifle 176 are moved to the right toward the position shown by solid lines, the rate of feed is progressively increased until a maximum rate is obtained when the parts are in the position shown in solid lines.

it is desirable to control the position of grinding plate 170 at a point remote from the hammer mill and preferably from the work floor 22 and at a position adjacent the controls for the main motor 102. To this end the connections to control motor 206 such as the connections 292 pass upwardly through work floor 22 to junction box 294 (see Figure 1). Connected to junction box 294 by leads 296 is a control box 293. Control box 298 has positioned thereon a stop button 300, a close button 302 and an open button 304. Also associated with the button 302 is an indicatorlight 306 which is lighted when the grinding plate 170 is moved to the fully closed position as shown in dotted lines in Figure 3. Another indicator light 308 is provided below the open button 304. Light 308 is energized when grinding plate arrives at the fully opened position which is illustrated by the solid line position of the parts as seen in Figure 3. When it is desired to decrease the rate of feed to the hammers 98, close button 302 is pushed and when the desired rate of feed has been obtained, the stop button 300 is pushed. Closure of switch button 302 energizes motor 206 and causes operation thereof in a direction to move grinding plate 170 to the left as seen in Figure 3. Conversely when it is desired to increase the rate of feed to the hammers 98, the open button 304 is pushed to cause motor 206 to operate in the opposite direction. This moves grinding plate 107 to the right as seen in Figure 3. When grinding plate 170 arrives at a position corresponding to the desired rate of feed, stop button 300 is pushed.

In order to prevent injury to the various moving parts when grinding plate 170 reaches the fully closed or the fully opened position, means is provided to deenergize motor 206 automatically when the grinding plate 170 is in either the opened or closed position. To this end a housing 310 is secured to housing 218 and carries therein a cam engageable with a switch. The cam is carried by a shaft 312 which has mounted thereon a sprocket 314 cooperating with chain 316. Chain 316 engages a sprocket on a shaft forming a part of the universal couplings 210 so that operation of motor 206 turns shaft 312 and the cam attached thereto. The switch engaged by the cam on shaft 312 when in engagement with the cam opens the circuit to motor 206 whereby to stop rotation thereof. The cam on shaft 312 engages and opens the switch when grinding plate 170 reaches the fully closed position of the feed inlet and when it reaches the fully opened position ofthe feed inlet.

Shaft 312 also carries the rotor of a position selsyn which is also positioned within housing 310. The information from the selsyn is conveyed by lines 318 to another selsyn mechanism generally designated by the numetal 320 which is positioned adjacent the control box a ssaau 9. 298 (se.e= Figure---1:)'. Selsyn 320 has a'n indicator 3.22 which cooperates; with a. dial. 324 to indicatezthe. position ofgrinding plate-170 along the track members 182 -1.84.-. By this; arrangement the position of grindingjplate. 170 can be accurately determined and adjusted: at a. point remotefrom: the. hammer mill such as; above-the. work floor 22.

In order-to insure that suliicient air is suppliedto the; pneumaticiconveying system to form the air stream-carry; ing the ground material. through. delivery pipe 126,; an additionalsource of. air is provided, the amountof'air supplied by the additional source being substantially in, dependent. of'the position of grinding plate 170 andbaifie 1762 To this end. housing 5.0 has; formedinthe curved guidef'wall 58 thereof; an aperture 326 which extendsv sub-- stantiallythe width of housing 50. Positioned over.

aperture 326- isra" screen 328 received.- in. guides-330i Screen 328remov'esanylarge particles fromjthe: air: drawn through: aperture 326. Inaddition a curved. and. down? wardly directed shi'el'cl332 is provided over: screen 328 and extends the entire lengththereof as canbe best seen in Figure'4. Air drawn through. screen. 328. into aperture32'6- iscarried downwardly behind bafflev 110; and tothe grinding chamber, around; hammers 98. The: flow of air through this path is not obstructed by" material hei'ng fedto the hammers 98 and the amount of: air; being drawn in through this'path is substantially. independent: of the' position of baffle 176-within-housing '50; The. air flows downwardly through screen 44. carrying the ground material therewith, into pipe 38 and fan. 124: to 'form a part of the air stream to convey the ground; material upwardly through delivery'pipe 126.

The operationiof the hammer: mill. including: therfeed mechanism and'the controls therefor will now. be-described in-detail1 Preferably at the end of a grinding,

operation 'the grinding plate 170 and battle? 176 are moved toward the forward or closed position of the. feed inlet illustrated in dotted lines in Figure 3 of the: draw ingsby pushing theclose switch- 302 (see Figure 1).. Whenthe grinding plate 170 arrives at the fully 'closed position, the limit switch within housing 3 10 will be engaged by" the cam on shaft 312 to deenergize motor 2 0.6. Simultaneously the closed position indicatinglight 306 will be energized;

The next batch of material-to be'groundis-thenzark mitted into the sink 16 and flows downwardly to fill hopper 128' and comes against the bafile "176 Motor control handle 110 is then moved to the on position to energize the main drive motor 102. This begins rotation of; shaft 94 and places hammers 98 in operative. grinding condition, With the controls in, thesev positions, the indicator. 322 will indicate the closed, position upon scale 3214; and; meter 112 will indicate a low power input to; the main drive motor 102 Grinding is commencedby closing the open switch 304 thereby energizing motor 206 and causing operation of the gear train leading to nut sleeve 192 (see Figure '5 Rotation of nut sleeve 192 with respect to hearing block 194 moves shaft 172 to the right as shown in Figure 3 whereby gradually to increase the feed opening from hopper 128 into the hammers 98. When the grinding plate 170 reaches the desired position as indicated by the position of pointer 322, stop switch 300 is pushed to deenergize motor 206. This stops movement of grinding plate 170.

The above described operation admits material to be ground to the path of hammers 98 and the material is ground substantially by suspension grinding as it falls from the grinding plate 170. The ground material passes around with hammers 98 and falls through screen 44. Air passing from hopper 128 and through screen 328 form an air stream which carries the ground material through the pipe 38 under the urging of fan 134 and upwardly into the delivery pipe 126.

1'0 Alter-natively. the position-of: thegrinding; plate/.170 can be positioned. 'so as to obtainv the. maximum rated output from motor." 102. When it is. desired to operate according to these conditions, the grinding plate and bafile-176 are initially moved to'the fully closed position; The. open switch 304 is .then pushed to cause operation of=motor 20610 movegrinding plate 170to the right or toward the open positionas viewedin Figure 3. The operator meanwhile observesatheposition. of .the needleon meter 112. When meter 112. indicates that motor 102 is operating at. full. rated capacity; the stop button 300 isv pushed to stopv movement of .grinding plate 170 by. deenergizing motor 206.

Modern stock feeding practices require a. varietyof feeds of different. fineness of. grind for. various purposes. For. example, ingrindinghog feed small grainispreferably groundto afinenesssuch that it will pass. through a sfinch screen. Shelled cornfor. chicken feed is ground until it can pass througha A inch screen. Ontheother hand when grinding for dairy animals, ear corn and small grain is. usually ground together so that the product can pass througha- /a inchscreen. When grinding for steers, however, the: mixture. of ear corn and. small grains is ground toa fineness. such that it will pass through a-Za. inch or. 1 inch screen. Roughages. are preferably ground sothat they will pass. through a inch. screen. while alfalfamealmay be ground to the same. fineness as rough.- ages orupzto a coarseness so thatit will pass through. a l or 1% inchscreen, for feeding steers. In customgrind;

ing it is not always possible to arrange. the grinding,

schedule. so that all. feedsto beground-to a certainfinc ness. can. be ground atone time.v The, degree. of fineness of grinding, must be changed for a. new set .of feeds} Furthermore, prior. hammer mills have. necessitated. the changing: of. the screen such, asv screen 44 in the drawings for eachnew degree. of, fineness desired. Changing ofthe screen. 44 is time consuming. and unproductive particu: larlywhen, the. main controls are. positioned at a distance; from. the hammer, mill and. on a difierent. floor as ill'us' trated in Figure 1, of the-present drawings.

An important feature of the present invention lies. in thefact that a wide range of fineness of grinding can be achieved using .asingle screen 44. For example, with. a inch. screen, feed. can, be: ground from a finenessof /s; inch, to inch. Similarly using a /2 inchscreenfoi s.creen'44,'av fineness of grindv from 4inch to /2. inch can, be achieved. This important. feature? results in the fact: that. the: position: of the. lower edge of, grinding plate 170withrespect to the tips of the hammers. 98 can, be adjusted by moving pl'ate170, along the traclr'members 182-184. As has been explained above the lower edge of grinding;plate.170 is positioned. A3: inch from the ends of hammers 98- when. plate 170. is in. the fully closed posit-ion-as illustrated by dotted lines'inFigure 3 ofIthe. draw ings. The distance between. the lower edge. of plate 170 andtheends of hammers 98 progressively increases from inch to /2. inch as plate 170 is moved from. the fully closed position. to point 286. on track members 182 -184, It has been found that the degree of fineness of grind can be controlled effectively by positioning the lower edge of grinding plate 170 with respect to the ends of hammers 98. In general, the closer the lower edge of plate 170 is to the edge of hammers 98, the finer is the grind, and vice versa.

Accordingly, scale 324 can also be calibrated to indicate the fineness of grind as well as the position of plate 170 along track members 182184. The hammer mill described by suspension grinding grinds substantially all of the material being fed thereto at the first or initial pass so that by the time the material to be ground reaches screen 44 it has been ground to the desired fineness. For these reasons screen 44 is not used solely to form a trap for unground material and accordingly, finer grinds can be achieved although coarser screens 44 are utilized. This feature eliminates considerable waste effort in changing the screen 44 when the fineness of grind is changed. The operator need only push the closed or open switches 3tl2304 until the indicator 322 is at the desired point on scale 324. When indicator 322 reaches the desired point on scale 324, the stop button 300 is pushed to interrupt operation of motor 206 and stop movement of grinding plate 170. The machine is then in condition to grind the material to the set degree of fineness without changing screen 44, provided screen 44 is at least as large as the set degree of fineness.

It will be seen that there has been provided a hammer mill including a feed mechanism and controls therefor which fulfills all of the objects and advantages set forth above. Although a preferred form of the invention has been shown for purposes of illustration, it is to be understood that various changes and modifications can be made therein without departing from the spirit and scope of the invention. Accordingly, the invention is to be limited only as set forth in the following claims.

We claim:

1. A hammer mill comprising a set of rotating hammers, a prime mover to rotate said hammers, a material feed inlet to said mill to feed material to be ground to the arc of the throw to said hammers, a grinding plate mounted adjacent said arc and movable therealong, a baffie mounted adjacent said grinding plate and extending upwardly into said feed inlet, said grinding plate and baffle being movable to a position substantially to close said feed inlet and to a position fully to open said feed inlet, means to position said bafiie and said grinding plate with respect to said feed inlet and to'position the edge of said grinding plate adjacent said are to ward and away from said are to adjust the degree of fineness of grind, said edge moving away from said are along an arcuate path as said grinding plate is moved from the position closing said feed inlet to the fully opened position, an air inlet to said hammer mill positioned on the side of said bafile opposite said feed inlet to permit air to flow downwardly along said battle and said grinding plate and to the area around said hammers While separated from the material to be ground in said feed inlet, control means for said positioning means adapted to be positioned at a point spaced from said hammer mill, limit means for said positioning means to render said positioning means inoperative when said grinding plate is in the fully closed and the fully opened position, power output indicating means for said prime mover, and position indicating means for said grinding plate to indicate the position of said grinding plate with respect to said feed inlet and the arc of the throw of said hammers.

2. A hammer mill comprising a set of rotating hammers, a material feed inlet at the top of the mill to feed material to be ground into the upper arc of the throw of the hammers, and a grinding plate mounted adjacent said hammers and movable along the arc of the throw thereof, said grinding plate being movable to a position substantially to close said feed inlet and being movable to a multiplicity of positions to vary the size of said feed inlet, the position of the lower edge of said grinding plate moving gradually along an arcuate path away from the arc of the throw of said hammers as the grinding plate is moved from the position substantially closing said feed inlet to the position giving maximum size for said inlet, said lower edge being positioned approximately /s inch from said are when said grinding plate is in a position substantially to close said feed inlet and being approximately /2 inch from said arc when said grinding plate is at the point on said arcuate path nearest the fully opened position of said grinding plate.

3. A hammer mill comprising a set of rotating hammers, a material feed inlet at the top of the mill to feed material to be ground into the upper arc of the throw of the hammers, a grinding plate mounted adjacent said hammers and movable along an arcuate path adjacent thereto, electrical means to move said grinding plate from a position substantially to close said feed inlet to a position fully to open said feed inlet, the position of the lower edge of said grinding plate moving gradually along an arcuate path away from the arc of the throw of said hammers as the grinding plate is moved from the position substantially closing said feed inlet to the fully opened position of said feed inlet, and control means positioned remote from said hammer mill to control said electrical means whereby to efiect movement of said grinding plate at a point remote from the hammer mill.

4. A hammer mill comprising a set of rotating hammers, a material feed inlet at the top of the milltq feed material to be ground into the upper arc of-the throw of the hammers, a grinding plate mounted ad jacnt saidhammers and movable along an arcuate path adjacent thereto, electrical means to move said grinding plate from a position substantially to close said feed inlet to a position fully to open said feed inlet, the position of the lower edge of said grinding plate moving gradually along an arcuate path away from the arc of the throw 'of said hammers as the grinding plate is moved from the position substantially closing said feed inlet to the fully opened position of said feed inlet, and limit means automatically to deenergize said electrical means to stop movement of said grinding plate at a predetermined distance near said are and at a predetermined dis tance away from said are.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES American Miller and Processor, January 1949, page 167.

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