US2758699A

US2758699A - Stock feeding and distributing mechanism

Info

Publication number: US2758699A
Application number: US283281A
Authority: US
Inventors: Carl E Magnuson
Original assignee: General Mills Inc
Current assignee: General Mills Inc
Priority date: 1952-04-21
Filing date: 1952-04-21
Publication date: 1956-08-14
Anticipated expiration: 1973-08-14

Description

1956 c. E. MAGNUSON STOCK FEEDING AND DISTRIBUTING MECHANISM Filed April 21, 1952 3 Sheets-Sheet 1 INVENTOR CARL E. MAGNUSON y WATTORNEY 1956 c. E. MAGNUSON STOCK FEEDING AND DISTRIBUTING MECHANISM Filed April 21, 1952 3 Sheets-Sheet 2 INVENTOR CARL E. MAGNUSON A BY Arron/v2) Aug. 14, 1956 c. E: MAGNUSON STOCK FEEDING AND DISTRIBUTING MECHANISM Filed April 1, 1952 3 Sheets-Sheet 3 .FIG.7

INVENTOR CARL E. MAGNUSON L rromvsr United States Patent STOCK FEEDING AND DISTRIBUTING MECHANISM Carl E. Magnnson, Minneapolis, Minn., assignor to General Mills, Inc., a corporation of Delaware Application April 2'1, 1952, Serial No. 283,281

18 Claims. (Cl. 198-53) This invention relates to feeding mechanisms and more particularly to devices of this type which are designed to distribute a given stock of material among a plurality of processing units.

Various devices have been proposed in the past for feeding material, particularly granular or free-flowing material, from a single source of supply to two or more processing units. Some of these prior devices have utilized swinging hoppers which were moved back and forth periodically to feed part of the time to one unit and part of the time to another. Insofar as I am aware, however, such prior devices did not provide for feeding all of such stock to the feeding hopper of one of the processing units until such time as the rate of feed exceeded the capacity of such unit, and then automatically diverting the surplus stock to the feeding hopper of the next processing unit.

With the above prior art in mind, it is one object of the present invention to provide improved feeding mechanism for distribution of stock among several processing units.

Another object is the provision of a stock feeding device in which the feed hopper of an upper processing unit will be supplied to its full capacity before any of the material is diverted to the feed hopper of a lower unit.

Still another object is a stock feeding device in which the diversion or distribution of material from one unit to the other requires a minimum of moving parts.

A further object is a stock distributor of the above type in which the diversion from one unit to another is obtained by particular coordination of the relative location of the parts, with respect to the angle of repose of the material under the particular operating conditions encountered.

A still further object is the provision of a feed hopper in which a feeding platform is provided with gate means at one side controlling the discharge of material from the platform, and is also provided with an overflow edge at another side, across which materials may be discharged whenever the amount of material fed to the platform is greater than that which can be accommodated by the gate means.

Other objects and advantages of the application will be apparent from the following description in which certain preferred embodiments of the invention are described.

In the drawings forming a part of this application, and in which like reference characters indicate like parts,

Figure 1 is a partial side view, with certain portions broken away, of a multiple processing unit incorporating stock feeding and distributing mechanism according to the invention.

Fig. 2 is a partial top view of the device of Fig. 1.

Fig. 3 is a partial sectional view on the line 33 of Fig. 2.

Fig. 4 is a partial perspective view of the device of Figs. 1 to 3 showing the relative arrangement of the walls, gate and overflow edges, with the adjustable gate member in position.

Fig. 5 is a view similar to Fig. 4 with the adjustable gate removed.

Fig. 6 is a perspective view of the complete machine of Figs. 1 to 5 showing means for rapid vibration of the respective feeding platforms and processing units.

Fig. 7 is a partial sectional view similar to Fig. 3, showing details of the relationship between the various edges and the angle of repose of the material, and

Fig. 8 is a view similar to Fig. 7 of an alternate embodiment of the invention.

In Fig. 1, the multiple processing unit is shown as supported by a suitable frame indicated generally at 20. The various

individual processing units

22, 24, 26, 28, 3t), and 32 are mounted in this frame and are located one above the other in this particular device.

Units

22, 24, 26, 28, 3t), and 32 may, for example, consist of sieves or screens, or the supporting beds of separators of various types. Since the particular type of processing unit forms no part of the present invention, these units need not be further described.

At one end of the frame 20, the stock feeding and distributing mechanism of the present invention is located. This mechanism includes a plurality of feed hoppers indicated at 34, 36, 38, 40, 42, and 44, respectively, from top to bottom. The granular or free-flowing material to be distributed among the

processing units

22, 24, etc., is initially fed into the upper hopper 34 by one or more spouts 46. The hoppers are so arranged that all the material fed into the upper hopper 34 by spout 46 will be fed to the upper processing unit 22 until such time as the rate of supply of material through spout 46 is greater than the rate at which hopper 34 can discharge material to unit 22.

At this point any excess material will be fed from hopper 34 automatically to the next lower hopper 36 and will be supplied to processing unit 24 until the maximum possible rate of feed from hopper 36 is achieved. The flow will then continue to the next lower hopper 38, etc. Should the rate of stock feed to spout 46 be greater than can be accommodated by all of the processing units operating at capacity, the excess stock will be fed from one hopper to another through the

respective spouts

48, 50, 52, S4, and 56, and any surplus will finally be fed through lower spout 58 to a further collector or chute 60.

Since all of the

hoppers

34, 36, etc., may be essentially the same in construction, the details of the upper hopper 34 will first be described for convenience. This hopper 34 includes a feeding platform 62. In this case, the feeding platform 62 is substantially horizontal and is designed for vibration in the manner described below. In some cases the vibration of the platform 62 may be omitted and if desired, the platform may be inclined, subject to suitable adjustment of the various angles according to the teachings herein.

At one side of the feeding platform 62 adjustable gate means is provided for controlling the rate of feed of material from the platform to the first processing unit. As shown particularly in Figs. 2-5, the hopper includes first wall means 64 extending across the forward edge of the feeding platform 62. Wall means 64 is provided with a feed opening. In this case, the lower edge 66 of the wall 64 is spaced above the top surface of feeding platform 62 and thus provides an opening 68 between the edge 66 and the platform. If edge 66 is considered as the upper edge of the feed opening 68, it is apparent that the wall portion 64 extends upwardly above the opening and that the top 70 of Wall 64 is spaced a substantial distance above the upper edge of the opening.

The opening 68 represents the maximum possible opening provided in the front wall 64. In order to provide for adjustment of this opening to a smaller capacity, the front wall is provided at each edge with guides 72 spaced forwardly of the wall and designed to retain a vertically movable gate member 74 (Fig. 4). The lower edge 75 of this gate member 74 may then be adjusted to a point below the level of edge 66 of opening 68 so that in effect the lower edge 75 of gate 74 then becomes the upper edge of the opening.

Gate 74 is provided at its ends with projecting arms 7 6 and 78 which may be attached to gate 74 by welding. These arms extend laterally beyond the hopper and are connected to mounting blocks 80 at each side of the apparatus by means of bolts 82. The blocks 80 are split as indicated at 84 and provided with locking bolts 86 so that these blocks may be clamped adjustably to vertically movable feed control rods 88 at each side of the unit.

Control rods 88 are supported on the frame 20 for vertical movement and are carried in lower guides 90 and upper guides 92. The cross section of the portions of the control rod passing through the guides may be noncircular, or other means may be provided to prevent rotation of the rods, in addition to the clamping effect of blocks 80.

The upper end 'of each control rod 88 is threaded at 94 for engagement of a rotary adjusting member 96. This adjusting member 96 is internally threaded to fit the threaded rod ends 94 and is provided with a scale 98 cooperating vw'th a suitable index 100 on the upper guide member 92. Thus by rotation of the control knob 96 either rod 88 may be raised or lowered, to raise and lower the corresponding ends of the associated gate members 74. The indicia on the knobs permit setting of the rods at each side of the apparatus to the same height or to slightly different heights as desired, and these control knobs provide for simultaneous adjustment of all gates. As pointed out above, the gates may be adjusted individually by loosening the clamping screws 86 associated with the mounting blocks for each gate.

A spring 102 is mounted on each rod 88 between one of the lower bearing members 90 and one of the mounting blocks 80 to urge the rod 88 downwardly at all times. Thus the springs 102 hold the rods and gates down as far as the particular adjustment of control knobs 96 will permit. At the same time, this resilient arrangement permits both control knobs to be lifted manually against the action of spring 102 to raise the gates to their completely open position in case it is desired to clear the gates 'of any obstructions. Certain details of the gate mechanism shown but not claimed herein are claimed in a co-pending application of Badavas et al., Serial No. 283,282, filed April 21, 1952, and assigned to the same assignee as the present invention.

According to the present invention an overflow edge is provided at another side of the feeding platform 62. As shown in Fig. 4, the overflow edge 104 in this case is at the rear or opposite end of the platform from the feed gates and constitutes the upper edge of a vertical rear wall portion 106 which extends upwardly from the rear edge 108 of the feeding platform 62.

Additional

side wall members

110 and 112 project upwardly from the remaining sides of the feeding platform 62 between the first wall means and gate assembly and the rear wall or overflow edge.- The various walls thus provide a hopper area into which material may be fed.

The

side Walls

110 and 112 project rearwardly beyond the overflow edge 104 as shown at 114 and 116 and are joined together by a rear wall or plate 118 which is spaced away from the overflow edge 104 and thus provides a discharge space between the wall 118 and overflow edge. The rear wall 106 on the feeding platform has a portion extending downwardly and inclined forwardly at 120 which cooperates with a similar forwardly inclined wall portion 122 on rear wall 118 to provide a second chute or spout through which material spilling over the overflow edge 104 may be guided to the next lower feeding hopper 36. The lower edge 124 of inclined rear wall 122 thus constitutes a discharge edge from which material is fed into the feeding platform of hopper 36. A similar discharge edge 126 on the initial feed or supply chute 46 discharges the material initially onto the upper feeding platform 62.

As shown in Fig. 3, the material 128 is initially fed by the supply chute 46 to form a pile or body of material on the feeding platform 62. If the particular apparatus is stationary or at rest, as may be the case for some applications, there will be a certain angle of repose which is characteristic of the material 128 when it rests on the stationary feeding platform 62. This angle of repose is illustrated by the upper surface 130 of the pile of material in Fig. 3.

According to a preferred form of the invention, the relative location of the overflow edge 104 and the top 70 of the front wall and gate means is correlated with the angle of repose of this surface 130 so as to insure that excess material will always pass the overflow edge 104 into the second chute means 48 before the material 128 can be piled sufficiently high on feeding platform 62 to run over the top 70 of the gate assembly. One way of stating this condition is to specify that the plane passing through the overflow edge 104 and the top 70 of the front wall means is inclined more steeply than the angle of repose which is characteristic of the material on the platform for the particular condition of operation. This plane is indicated by the dotted line 132 and slopes downwardly from front to rear toward the overflow edge 104 more steeply than the angle of repose illustrated at 130 for the top surface of the pile of material 128.

In the particular case illustrated in connection with hopper 34, the discharge edge 126 of the first supply chute 46 is also located in such a manner that material will spill over the overflow edge 104 before it blocks the further discharge of material from chute 46. To obtain this condition of operation, chute 48 must be capable of receiving as much material as chute 46 can discharge, and the relative location of discharge edge 126 and overflow edge 104 must be such that the plane 133 defined by said edges is also inclined more steeply than the angle of repose of the material under the particular operating conditions. As shown in Fig. 3, this plane 133 is inclined more steeply than the upper surface 130 which illustrates the angle of repose of material 128 when the device is stationary.

Another way to state the foregoing requirements is to consider the top layer 130 of the material as the surface of repose thereof. In this case both the top of the front wall 70 and the discharge edge 126 may be said to be located above this surface of repose of the material when the material just begins to spill over the discharge edgc 104, i. e., when the surface of repose passes through such overflow edge 104.

The surface of repose illustrated in hopper 34 of Fig. 3 is substantially a plane inclined downwardly toward the overflow edge 104. It is possible, however, that the surface of repose of the material may involve a nonplanar or complex surface under particular operating conditions and particular relative locations of the parts. The surface illustrated at 130 would be expected when the device was stationary and when the discharge spout 46 feeds the majority of the material toward the forward wall means. Should the material be fed farther toward the rear, it is possible that the surface of repose would be more like that shown in hopper 38 of Fig. 3 where the upper surface 134 of the material has its rear portion inclined downwardly toward the overflow edge 136 and its forward portion inclined downwardly toward the front wall. Here again, both the discharge edge 137 of feed spout 50 and the top 1380f the front wall and gate assembly are located above this surface of repose when the material begins to overflow the edge 136.

.gate opening at 142. 'hopper is thus located above the surface of repose 140 of the material when the latter surface is high enough -of operation.

According to another feature of the invention, it is desirable to insure feeding of the maximum amount which can be accommodated by any of the individual gate means before any material passes the overflow edge of the hopper in which such gate means is located. This condition is illustrated in hopper 40 of Fig. 3 where a relatively small amount of material 128 has been fed within the hopper. As illustrated, the upper surface 140 of this material is just high enough to fill completely the The overflow edge 144 of this to reach the top of the gate. Stated in other terms, the

relative arrangement of the parts is such that the overflow 'edge 144 is higher than the upper edge of opening 142 and a plane (indicated at 146) defined by the overflow edge 144 and upper edge of opening 142 is inclined down- 'wardly toward the opening more steeply than the angle of repose of the material under the particular conditions The condition shown in hopper 40 is that in which the upper surface 140 of the material lies sub- :stantially in an inclined plane such as might be the case when the material is initially fed to the rear portion of the feeding platform just ahead of the overflow edge 144.

In hopper 42 of Fig. 3 another possible surface of :repose of the material 128 is illustrated. Here the surface of repose includes a rear portion 148 which slopes downwardly toward the rear of the feeding platform, and :a forward portion 150 which slopes downwardly toward the feed gate. As larger and larger quantities of material :are fed to hopper 42 this upper surface of the material 128 may successively rise to the positions indicated in dotted lines at 152 and 154. It will be noted in connection with these positions, that when this surface of repose just reaches the upper edge ofgate 156, as shown by the solid pile of material, the overflow edge 158 will be located well above this surface of repose. As the surface rises with the addition of further material, it ultimately reaches a point where the surface of repose is at the same height as the overflow edge 158 so that material will begin to spill over into the discharge chute 56. At this particular time, the top 160 of the front wall and the discharge edge 162 of the chute. 54 will both be located above this surface of repose so that no material can overflow the front wall and so that the further feed from chute 54 will not be blocked.

In many cases it is desirable to use a feeding mechanism in which the feeding platforms are agitated or vibrated to promote the flow of the material. Fig. 6 illustrates a method of mounting of the device of Figs. 1-5 which provides for such vibration. Here the frame member 20, previously described, is supported on inclined springs 164 which are connected at their upper ends to brackets 166 on frame 20. The lower end of each spring 164 is secured at 168 to a suitable base 170. The resilient supporting springs 164 permit reciprocation of the frame and its associated parts, including the feeding hoppers and their respective feeding platforms. Here, the desired vibration is provided by a connecting rod 172 (Figs. 3 and 6) which is pivoted at 174 to a bracket 176 at the rear of frame 20. The other end of connecting rod 172 is mounted at 178 on an eccentric carried by shaft 180 driven by motor 182. Shaft 180 and the motor 182 may be supported on the base 170 by suitable brackets 184. When the motor is energized and the shaft rotates, the eccentric will impart movement to the connecting rod 172 and thence to the frame 20 and will thus cause rapid reciprocation of the frame 20 in a direction perpendicular to the plane of the springs 164. This direction is illustrated by the arrow 186 in Fig. 6.

Because of the particular inclination of springs 164, this direction of vibration shown by arrow 186 will have a substantial component perpendicular to the plane of the respective feeding platforms such as 62. This perpendicular component is represented by; the arrow 188 6 of Fig.6. The vibrations will also have a substantial component in the plane of the various feed platforms and extending from the rear toward the front of the device, i. e., from the overflow edge toward the gate opening of each hopper. This component is illustrated by the arrow 190 in Fig. 6.

Obviously the angle or surface of repose which is characteristic of the particular material on the feeding platform 62 when the latter is stationary may be quite different from the angle of repose which is characteristic when the device is vibrated. Ordinarily this angle of repose is thought of as inclined downwardly toward that portion of the apparatus where a particular flow of material is being considered.

The theoretical consideration of the angle of repose may be facilitated bystudy of Fig. 7 in which the feeding platform 62 and associated parts of the upper supply hopper 34 of Figs. 1 to 6 are shown in enlarged section. Here the material 128 is illustrated under operating conditions in which the upper surface of the pile will have two angles of repose which are quantitatively the same, but which are inclined in opposite directions depending upon whether one is considering the possible flow of materials to the rear of the hopper past overflow edge 104 or whether one is considering the flow of material toward the front wall and feed gate. Such a condition could be achieved, for example, with the apparatus stationary.

Here the rear portion of the surface of repose is shown at 192 inclined downwardly from the top of the pile toward the overflow edge 104. The quantity of material is just sufficient so that addition of further material will result in such material rolling down the surface 192 and past the overflow edge 104. If this surface of repose 192 is extended rearwardly, as shown by dotted line 194, until it intersects at 196 the plane of feeding platform 62 (extended by dotted line 198) the angle of repose may be considered as the angle indicated by arrow 200.

To illustrate the inclination of the plane 132 defined by overflow edge 104 and the top 70 of the front wall of the hopper, this plane has been extended rearwardly until it also intersects the plane of feeding platform 62 as shown at 202. Here the angle indicated by arrow 204 can be considered the angle of inclination of plane 132. As indicated above, this angle is greater than the angle of repose 200 of the material surface 192. Thus the material will always pass rearwardly across overflow edge 104, before there is any possibility of the material accidentally passing forwardly above the top 70 of the front wall,

Similarly, the pile of material 128 has a surface 206 inclined from the top of the pile downwardly toward the front wall and gate assembly. If this surface is extended as shown by dotted line 208 to its point of intersection 210 with the plane of feeding plat-form 62, the angle indicated by arrow 212 will be the angle of repose of the material with respect to the forward direction of feed. If the device is assumed to be stationary as suggested above, this angle 212 will be quantitatively the same as the angle of repose 200 of the rear surface of the material.

As already pointed out, it is preferable to insure complete maximum flow through the feed gate before any of the material is permitted to pass rearwardly across overflow edge 104. Therefore the plane indicated at 214 which is defined by the overflow edge 104 and the upper edge of the feed opening must be inclined more steeply or more positively than the surface 206. If this plane 214 is extended to its line of intersection 216 with the plane of feeding platform 62, the angle indicated by arrow 218 will be a measure of the inclination of the plane. In other words, angle 218 must 'be greater than angle 212 in the arrangement shown in Fig. 7.

The foregoing analysis is readily understandable when the apparatus is stationary and when the surface of respasms pose of the material actually does incline downwardly toward either the overflow edge 104 or the upper edge 75 of the feed opening, as the case may be. For convenience in the analysis and understanding of other possible situations, this angle of repose will be considered a positive one. In other words, if the slope of the upper surface of the material is downwardly toward the point at which transfer of the material is being considered, the angle of repose may be considered positive.

Under particular conditions of vibration or operation, however, it is possible that the surface of the material will actually be inclined in the opposite direction. Such a reverse condition, i. e., one in which the .surface of the material inclines upwardly toward the point at which the transfer is being considered, may be thought of as having a negative angle of repose, i. e., an angle of repose normally feeding the material back away from the point rather than through it or across it.

Fig. 8 illustrates a situation in which both positive and negative angles of repose are encountered, depending on the direction in which the feed is being considered. Here the feeding platform 220 may be mounted for rapid vibration in a direction illustrated by arrow 221, i. e., a direction having components directed perpendicularly of the platform and also longitudinally thereof. For certain conditions of vibration, there may be a tendency for the material 128 to have its upper surface 230 inclined upwardly from the rear toward the front of the platform under the action of the particular driving forces. Here the feeding platform 220 has front wall means 222, the top of which is shown at 224. An adjustable gate member provides an upper edge 226 for the feed opening 228 beneath wall 222.

If one first considers the angle of repose in the sense of material feeding from the rear of the device toward thef'eed opening 228, and if it is assumed that the surface 230 of the pile of material 128 is inclined upwardly from the rear toward the front wall at all times, then it will be apparent that the angle of repose indicated at 232 for this surface 230 is a negative angle of repose in the sense just discussed. On the other hand, if one is considering the possibility of the material passing rearwardly over the overflow edge 234, then this angle of repose 232 will be a positive one since the surface 230 is inclined downwardly toward this rear edge. It will be shown that the various planes previously discussed still fit the conditions recommended for the preferred operation of the invention.

For example, the plane 236 which is defined by and passes through the overflow edge 234 and the top 224 of front wall 222 is also inclined downwardly toward the overflow edge 234 and thus has a positive angle of repose indicated at 238. Obviously, this angle 238 is greater than the positive angle of repose 232 of the surface 230. In other words, as more material is added to the pile, the upper surface 230 will rise to a higher and higher level remaining always substantially parallel to itself, until the point 239 (at which the surface of the pile intersects the feeding platform 220) actually reaches rearwardly to the overflow edge 234. At this point additional material will pass rearwardly past the overflow edge 234. Yet because of the greater inclination 238 of plane 236, there will be no possibility of the material 128 passing forwardly over the top 224 of front'wall 222 before such discharge can occur.

With reference to movement of the material in a forward direction, the plane 240 defined by overflow edge 234 and the upper edge of opening 228 must be considered. In the previous embodiment of this device the overflow edge 234 has been higher'thanthe upper edge 226 of the feed opening. Thus the inclination of this par- 'ti'cular plane, indicated by arrow 242, has always been positive when one considered the feeding of material for- Wa'rdly'b'en'eath the gate. Here, however, the particular conditions of operation which provide a surface of repose such as shown at 230 make it possible to eliminate the rear wall portion such as 106 of Fig. 7 and to locate the overflow edge 234 directly in the plane of the feeding platform 220.

Thus the angular inclination of plane 240 represented by arrow 242 will in this case be negative. At the same time the angle 232, which is a measure of the inclination of the surface of repose 230 of the material, is also negative with respect to the forward direction of feed as pointed out above and is obviously greater in quantity than the angle 242. Stated in another way, the angle of repose 232 of the material is more negative than the angle of inclination 242 of the plane 240. Conversely, the plane 240 which passes through the overflow edge 234 and the upper edge 226 of feed opening 228 is inclined at a more posi: tive slope than the angle of repose 232 of the material (even though quantitatively the angle looks smaller).

From the foregoing discussion, it is apparent that certain of the claims herein, in the use of the term more steeply inc-lined or more positively sloped contemplate the possibility 'of situations in which the angle of repose will .be negative in the sense outlined. Whether :such angles are actually negative or positive in a particular case, the teachings of the :present invention enable the design and construction of feeding mechanisms in which the .ob-

jects set forth at the beginning of this specification are accomplished and in which an upper feeding hopper will operate to its full capacity :before any material is discharged-to a lower feed hopper. The device permits operation of a plurality .of processing units at a maximum :of efficiency, even 'where the supply of material .is received at volume :rates which vary too widely for a single processing unit'to accommodate.

Since minor variations andchanges in the exactdetails of construction will *be apparentto persons skilled in this field, it is intended that this invention shallcover all such changes and modifications as fall within the spirit and scope ofthe attachedclaims.

'Now, therefore, I claim:

1. A feeding hopper for granular or free-flowing materials comprisin'g a feed platform, first wall means atone end of "the'platform providing agate opening with upper andlower edges between which a-predetermined -volum-e rate of material may be fed from :the platform, 'saidwall means having a portion extending upwardly above the opening from said upper edge, an overflow edge at the opposite end of the platform, retaining walls on the remaining sides of :the platform between the first wall means and over-flowedge, said-overflow edge being located at a level below the tops of said upwardly extending wall portion and saidretaining walls, and means forfe'e'ding material onto the platform between the first wall means and .overflow edge at a volume rate which may 'exceed the pre-determined rate for which said feed opening is set, -:the relative size and location 'of'said fee'dmg means,first wall means, and-overflow edge automatically insuring passage-across the'overflow edge of all material which thefeeding means delivers in excess of that which-can be discharged through the gate opening.

2. A feeding hopper according to claim 1 in which said overflowedge is located at a :level above the upper edge Of'zSfliCl :gate opening.

3. .Aife'eding hopper accordingto claim 2 in which =a plane'passing through said-overflow edge and the top'of said upwardly extending .wall portion is inclined at a more positive slope than the angle of repose of the material-underltheiparticular conditions of operation of the: platform.

'4. A feeding-hopper according to claim 3 in which a plane passing throughsai'd overflow edge and the upper edge of said gate opening is also inclined =at-a more positive slopedhanthewangleof repose of the material under ,the'particular conditionsof operation of the unit.

'5 'A 'feeding hopper- -according to claim 4 havingmeans rapidly vibrating theplatform.

6. A feeding mechanism for granular or free flowing materials comprising a feed platform, gate means projecting upwardly at one side of the platform and provid-' ing an opening through which a predetermined volume rate of material may be fed from the platform, a feed spout having a discharge edge located above the platfOIlll behind the gate means for discharging material onto the platform at a volume rate which may exceed the predetermined rate for which said opening is set, and an overflow edge on said platform located behind both the gate means and said discharge edge the relative size and location of said feed spout, gate means, and overflow edge automatically insuring passage across the overflow edge of all material which the feed spout delivers in excess of that which can be discharged through said openmg.

7. A feeding mechanism according to claim 6 in which said discharge edge is located above the surface of repose of the material under the particular conditions of operation of the mechanism, when such material is passing across the overflow edge.

8. A feeding mechanism according to claim 6 in which said overflow edge is lower than said discharge edge, said mechanism also having means rapidly vibrating the platform in a direction having a substantial component perpendicular to the platform and a substantial component in the plane of the platform from said overflow edge to ward said gate means.

9. A feeding hopper for granular or free-flowing materials comprising a substantially horizontal feed platform, first wall means at one side of the platform having a gate opening through which a predetermined volume rate of material may be fed from the platform, the gate opening having an upper edge spaced below the top of said wall means, an overflow edge at another side of the platform for discharge of excess material from the platform, means for feeding material onto the platform between said wall means and overflow edge at a volume rate which may exceed the pre-determined rate for which said gate opening is set, said feeding means including a discharge edge spaced above the platform, and means for vibrating the platform, said overflow edge being lower than the discharge edge and lower than the top of said first wall means, with the plane which passes through the top of said first wall means and said overflow edge inclined at a more positive slope than the angle of repose which is characteristic of the material on the platform when the latter is stationary, and with the plane which passes through the overflow edge and the upper edge of said opening inclined toward the opening at a more positive slope than the angle of repose which is characteristic of the material on the platform when the latter is vibrating, the relative size and location of the feeding means, the gate opening, and the overflow edge, during vibration of the platform, automatically causing material to spill over the overflow edge only when the platform is receiving more material than can pass through said opening during such vibration and said relative sizes and locations, when the platform is stationary, automatically causing the material to spill over the overflow edge instead of the first wall means.

10. A feeding hopper according to claim 9 in which the plane which passes through the overflow and discharge edges is inclined at a more positive slope than the angle of repose which is characteristic of the material when the platform is vibrating.

11. A feeding hopper according to claim 10 in which the plane which passes through the overflow and discharge edges is also inclined at a more positive slope than the angle of repose which is characteristic of the material when the platform is stationary.

12. A feeding hopper for granular or free-flowing materials comprising a substantially horizontal feed platform, first wall means at one end of the platform having a gate opening through which a predetermined volume 10 rate of material may be fed from the platform, the gate opening having an upper edge spaced below the top of said wall means, an overflow edge at the opposite end of the platform for discharge of excess material from the 1 platform, means for feeding material onto the platform between said wall means and overflow edge at a volume rate which may exceed the pre-determined rate for which said gate opening is set, said feeding means including a discharge edge spaced above the platform, and means for vibrating the platform, said overflow edge being lower than the discharge edge and lower than the top of said first wall means, with the plane which passes through the top of said first wall means and said overflow edge inclined more steeply than the angle of repose which is characteristic of the material on the platform when the later is stationary, and with the plane which passes through the overflow edge and the upper edge of said opening inclined toward the opening at a more positive slope than the angle of repose which is characteristic of the material on the platform when the latter is vibrating, the relative size and location of the feeding means, the gate opening, and the overflow edge, during vibration of the platform automatically causing material to spill over the overflow edge only when the platform is receiving more material than can pass through said opening during such vibration, and said relative sizes and locations, when the platform is stationary, automatically causing the excess material to spill over the overflow edge instead of the first wall means.

13. A feeding mechanism for distribution of granular or free flowing materials among a plurality of processing units comprising at least two vertically spaced feed platforms, each of which has a forward area from which material is to be fed to a processing unit, gate means located at the forward area of each platform controlling the volume rate of material fed from the platform, a feed spout having a discharge edge located above the upper platform behind the gate means for discharging material onto the platform at a volume rate which may exceed the rate at which material may be fed under the gate, an overflow edge on the upper platform located behind the gate and behind said feed spout discharge edge, and conveying means having a receiving portion positioned adjacent said upper platform overflow edge for receiving the material passing over said edge and also having a discharge portion above the next lower platform behind the gate means of the latter for conveying to the lower platform the material fed to the upper feed platform and spilling over said overflow edge of the upper platform, the relative size and location of said feed spout, gate means and overflow edge automatically causing passage across the overflow edge and along the conveying means on to the next lower platform of all material which the feed spout delivers to the upper platform in excess of that discharged by the upper platform gate means.

14. A feeding mechanism for distribution of granular or free flowing materials among a plurality of processing units comprising at least two vertically spaced feed platforms, each of which has a forward area from which material is to be fed to a processing unit, gate means located at the forward area of each platform controlling the volume rate of material fed from the platform, a first feed spout having a discharge edge located above the upper platform behind the gate means for discharging material onto the platform at a volume rate which may exceed the rate at which material may be fed under the gate, an overflow edge on the upper platform located behind the gate and behind said feed spout discharge edge, and a second feed spout having an inlet positioned adjacent said upper platform overflow edge for receiving the material passing over said edge and also having a discharge edge above the next lower platform behind the gate of the later thereby providing means for conveying to the lower platform material fed to the upper feed platform and spilling over said overflow edge of the upper platform the relative size and location of the.

1 1 said feed spout, upper platform gate means, and overflow edge automatically insuring passage across the "Over- 'flow edge through the second feed spout on to the next lower platform of all material which 'the first fe'ed spout delivers to the upper platform in excess 'of that discharged by the upper platform gate means.

15. Feeding mechainsm according to claim 14in which each of said gate means has an opening with its upper edge spaced below the top of the gate means and in which the planes which pass through the overflow edge and the upper edge of the opening of each platform are inclined toward the openings at a more positive slope than the angle of repose which is characteristic of "the material o'n the platform under the :particular conditions of operation.

'16. A feeding mechanism according to claim 14 in which the planes which pass through the overflow edge of each platform and the discharge edge of the associated spoutare each inclined more steeply than the angle of repose which is characteristic of the material on the platforms when the latter are stationary.

17. Feeding mechanism according to claim 16 having means for rapidly vibrating each platform.

of repose which is characteristic of the material on th'e.

platforms when the latter are vibrating.

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