US2587531A - Method of and apparatus for proportioning the constituents of materials - Google Patents

Description

W. E. SAXE METHOD OF AND APPARATUS FOR PROPORTIONING THE Feb. 26, 1952 2,587,531

CONSTITUENTS OF MATERIALS 5 Sheets-Sheet 1 Filed Feb. 5, 1951 KM? xv m RH m MM Q L m M H Y E& R RE my 90 5F HH K R R a H Feb. 26, 1952 w, E, s 2,587,531

METHOD OF AND APPARATUS FOR PROPORTIONING THE CONSTITUEINTS OF MATERIALS Filed Feb. 5, 1951 3 Sheets-Sheet 2 /42 we /44 as /Z5 126 I27 I28 wa m Feb. 26, 1952 w SAXE 2,587,531

METHOD OF AND APPARATUS FOR PROPORTIONING THE CONSTITUENTS OF MATERIALS 5 Sheets-Sheet 3 Filed Feb. 5, 1951 lNvfiNTOQ. Wan/s1? 5. Sex):

5K H/S ATTORNEYS.

R R H H a R m m C m K K e M Patented F eb. 26, 1952 METHOD OF AND APPARATUS FOR PRO- PORTIONING THE CONSTITUENTS OF MATERIALS Walter E. Saxe, Pasadena, Calif., assignor to The Conveyor Company,

Inc., Los Angeles, Calif., a

corporation of California Application February 5, 1951, Serial No. 209,500

24 Claims.

The present invention relates to a method of and apparatus for regulating the proportions of the constitutents of a multiple-constituent material, a primary object of the invention being to provide a method of and apparatus for proportioning the constituents of such a material by separating the constitutents of a sample of the material from each other and by subsequently mixing the separated constituents derived from the sample with the residue remaining after sampling in such proportions as to provide the resulting mixture with the desired proportions of the various constituents.

More particularly, a primary object of the invention is to provide a method of and apparatus for dividing the material into a sample and a residue, separating the constituents of the sample from each other, storing the separated constituents of the sample independently of each other, mixing variable proportions of the stored constituents of the sample with the residue, and varying the proportions of the stored constituents of the sample which are mixed with the residue inversely with deviations in the proportions of the constituents of the original material from prescribed values so as to maintain the proportions of the constituents of the resulting mixture substantially equal to the prescribed values.

In accordance with the preferred embodiment of the invention, an initial sample is separated into its constituents, which are stored separately and subsequently mixed in variable proportions with the initial residue remaining after the initial sample is taken. Thereafter, the resulting mixture is divided into a final sample and a final residue and the constituents of the final sample are separated from each other and the proportions thereof are measured, the proportions of the stored constituents of the initial sample which are mixed with the initial residue being varied inversely with deviations in the measurements of the proportions of the separated constituents of the final sample from prescribed values so as to maintain the measurements of the proportions of the constituents of the final sample substantially equal to the prescribed values, With this construction, the proportioning of the constituents of the mixture is checked for accuracy after the proportioning has taken place, which is an important feature of the invention.

An important object of the invention is to provide an apparatus for performing the foregoing operations automatically and continuously.

Another object is to provide a plurality of variable speed proportioning means respectively associated with storage bins in which the constituents of the initial sample are stored for dispensing the constituents of the initial sample from the storage bins in variable proportions, and to provide a control means responsive to the proportions of the constituents of the final sample for varying the speeds of the variable-speed proportioning means inversely with deviations in the measurements of the proportions of the separated constituents of the final sample from prescribed values. In other words, if the proportion of a particular constituent of the final sample is below the prescribed value, the speed of the corresponding variable-speed proportioning means is increased and vice versa.

While the present invention may be employed to proportion the constituents of a material in accordance with any suitable characteristic of such constituents, such as weight, volume, and the like, I prefer to proportion the constituents of the material by weight and embodiments of the invention for proportioning the constituents of the material by weight are disclosed hereinafter for purposes of illustration.

Also, the invention is applicable to proportioning materials having constituents of various types. For example, the constituents to be proportioned may differ in size, specific gravity, color, or the like, the invention being considered hereinafter in connection with proportioning constituents differing in size as a matter of convenience.

The invention finds particular utility in controlling the proportions of said particles of different sizes and will be considered in such connection hereinafter for illustrative purposes. As is well known, sand is employed extensively in the building industry in concrete and the like, concrete for different purposes requiring diiferent proportions of particle sizes for the sand employed therein. The present invention is well adapted to controlling the proportions of sand particle sizes so as to maintain the proportions thereof substantially equal to certain desired or prescribed values, which is an important feature of the invention.

The foregoing objects and advantages of the present invention, together with various other objects and advantages thereof which will become apparent, may be attained with the two exemplary embodiments of the invention which are illustrated in the drawings and which are described in detail hereinafter in connection with the proportioning of sand-particle sizes by Weight. Referring to the drawings:

Fig. l is a diagrammaticperspective view of a preferred embodiment of an apparatus of an invention which is capable of performing a preferred embodiment of the method thereof;

Fig. 2 is a schematic diagram of an electrical circuit of the apparatus illustrated in Fig. 1; and

Fig. 3 is a diagrammatic perspective view of an alternative embodiment of an apparatus of the inventioncapable" of performing an alternative embodiment of the method thereof.

Referring particularly to Fig. 1 of the drawings, the apparatus illustrated therein includes a chute H for delivering sand or other material whose constituents are to be proportioned to a conveyor 12, the sand preferably being delivered to the conveyor l2 in the form f a sjub stantially continuous stream. Theconveyor I2 discharges the sand into a rotatable hopper I3, the latter being mounted on a shaft H which" may be rotated in any suitable manner, not shown, to rotate the hopper [3 about the axis of such shaft. The rotatable hopper l3'is provided with an offset spout l5 through chthefsand discharged into this hopper flows.

Below the rotatable hopper I3 is a stationary hopper l8 having stationary spout I9 which discharges onto 'a conveyor the latter discharging into a hopper'2ll' The stationary hopper I8 is provided with 'a dividing or splitting means 22 for splitting off a sample stream from the stream of sand ed"into the stationary hopper I8 by'the rot ble hop-per l3. The splitting means 22'is ill str ted as comprising a I-shaped compartme 2'?;"the apex of which substantially coincidesv with a axis of rotation of the rotatable hopper l3.'"As will be apparent,

during each revolution of the" rotatable hopper IS, a sample of the sand dischargedby the offset spout falls into the compartment 23, the remainder of the sand discharged by the offset spout l5 being delivered to the conveyor 20. The sample discharged into the compartment 23 flows through 'a chute 25 into a hopper 25, the sample being discharged from "the latter through a chutezs' Thus, it will be apparent that the splitting means 22 divides the stream of material dis: charged from the rotatable hopper 13 into a sampleand a residue, the sa'rnple being delivered to the hopper 25 and the residue being delivered to the conveyor zfl. the sand is discharged into the rotatable hopper l3 by the conveyor [2 in a substantially continuous stream, as is preferable, it' will be apparent thatthe residue delivered to the conveyor is inthe form of asubstantially continuous stream. Under such conditions, the sample flows'through the chute'25 leading from the hopper in the form of a substantially continuous stream, the hopper 25, the chute 24, and the compartment 23 tending to level out the pulses resulting from the periodic discharge of sand into the compartment 23. If a still more uniform sample stream is desired, a splitting means similar to that disclosed in my application Serial No. 213,015, filed Februaryv 27, 1951, may be used.

The proportion of the sand which is split off by the splitting means 22 depends on a number of factors, as will be discussed in more detail hereinafter. However, I contemplate splitting off around tenpercent of the sand, for example. As will be apparent, if it is desired to split off ten percent of the sand, then it is necessary that the angle of the veshaped compartment 23 be 2 6. Qbyiously, if it isdesiredto split off greater or lesser percentages, this angle must be increased or decreased.

The chute 26 from the sample hopper 25 discharges the sample into means, which may be a trommel 30, for separating the constituents of the sand sample from each ether, each constituent of the sample being regarded as a particular range of particle sizes. As is well known in the art, the trommel 30 may include a plurality of screens each adapted to retain sand particles exceeding a predetermined size. In the particular construction illustrated, the trommel 30 is designed to separate the sand sample into four constituents, although this number may be varied as desired. The four constituents are conveyed through chutes 3], 32, 33 and 34, respectively, to storage bins 35, 3, 31 and 38, respectively.

The constituents of the sand sample in the storage bins 35, 36, 31 and 38 are delivered to a conveyor 39 by conveyors M, 42, 43 and M, respectively, the conveyor 33 discharging into the same hopper into 'w ich'thje conveyor 2?; dise charges the residue discussed above. Preferably, the conveyors 4|, 42, 43 and 44 are screw song veyors, although other types may be used. The conveyors 4 l 42, Q3 and 34 are driven by variable: speed electric motors {L5, 52$, 5] and d8, resp ee tively, the variable-spree tors 45, 46, 4? and 38 being controlled by slave synchros 5|, 5 2, 53 and 54, respectively, in 'the'p'a rticular construction illustrated. The manner in which the slave synchros 5| to 54 are'controlled to control the variable-speed motors 45 to 38 will be considered in more detail hereinafter.

The storage bins 35, 36 31 and 38 are provided with overflow spouts '55, 55, 5,1 and"58, respectively, through which the sand constituents are discharged from the storage bins when such bins are filled to capacity, the overflow spouts discharging onto an overflow conveyor 59 which leads to a suitable point of disposal.

Considering the operation of the embodiment of the invention illustrated in Fig. 1 of the drawings as thus far described, the sample obtained by the splitting means 22 is separated into its constituents by the trommel 30 and such constituents are discharged into the storage bins to 38, the residue remaining after the sample is taken by the splitting means being discharged into the hopper 2|. The conveyors M to discharge the constituents of the sample from the storage bins 35 to 38 onto the conveyor 39 in variable proportions, each of the conveyors 4| to M and that one of the variable-speed motors to 48 which is associated therewith thus serving as a variable-speed discharge or proportioning means of the apparatus. The variable propor tions of the constituents of the sample which are discharged onto the conveyor 39 are also discharged into the hopper 2| along with the residue discharged thereinto by the conveyor 2!}. Thus, the stored constituents of the sand sample are mixed in variable proportions with the residue remaining after the sample. has been taken, the proportions of the stored constituents which are mixed with the residue being so regulated as to provide the resulting mixture with certain prescribed proportions of the sand constituents as will be described in more detail in the following paragraphs.

The mixture of the variable proportions of the stored constituents of the sand sample with the. residue remaining after the sample is split off discharges from the hopper 2| into a stationary hopper 62 having an offset spout 63, the latter discharging onto a conveyor 64 which leads to a stock pile 55. Rotatable within the stationary hopper 62 is a central vertical shaft 58 which carries a splitting means 59 similar to the splitting means 22, the shaft 68 being rotatable in any suitable manner, not shown, to rotate the splitting means 69 within the stationary hopper 62. In the particular construction illustrated, the

* splitting means 59 includes a V-shaped compartment 79 having a spout H at its lower end.

As will be apparent, the mixture discharged into the hopper 52 from the hopper 2| falls into the V-shaped splitting compartment 19 once for each revolution thereof to obtain a sample of the mixture which will be termed a final sample to distinguish from the initial sample taken by the splitting means 22. This final sample may, for example, be of the order of magnitude of two percent of the mixture. The residue remaining after the final sample is taken by the splitting means 59 discharges through the spout 63 of the hopper 62 onto the conveyor 64 and is transported to the stock pile 55. This residue will hereinafter be termed the final residue to distinguish from the initial residue remaining after the initial sample is split off by the splitting means 22.

The final sample periodically discharged into the V-shaped compartment 19 is discharged therefrom through the spout ll into'a hopper 74 having a spout '55 which leads to another means, such as another trommel it, for separating the final sample into the same constituents as discussed previously. In other words, the trommel 30 separates four constituents of the initial sample from each other in the particular construction illustrated, and the trommel l8 separates the same four constituents of the final sample from each other, although the proportions of the four constituents of the final sample may diiier from those of the initial sample, as will be discussed in more detail hereinafter.

The four constituents into which the final sample is separated by the trommel F5 are delivered through chutes BI, 82, 83 and 34, respectively, to separate conveyors 85, 85, 8'! and 88, respectively, the latter discharging onto a conveyor 89 which preferably leads to the stock pile 55. Operatively connected to the conveyors 85, 85, 81 and 88 are scales SI, 92, 93 and 94, respectively. For illustrative purposes the scales 9| to 94 are shown as supporting the conveyors 85 to 88, although any desired conveyor scale system may be employed.

The scales 9|, 92, 93 and 94 actuate master synchros 95, 95, 91 and 98, respectively, the rotors, not shown, of the master synchros being operatively connected to the indicator shafts of the scales in any suitable manner, not shown. The master synchros 55, 95, 91 and 99 are electrically connected to the slave synchros 5!, 52, 53 and 54, respectively, which control the variable-speed motors 45, 45, 41 and 43, respectively. Since the electrical connections between the master and slave synchros are well known, they are not shown in detail, being represented diagrammatically by the connections I51, I02, !93 and 94.

Considering the over-all operation of the embodiment of the invention illustrated in Fig. 1 of the drawings, it will be assumed as a matter of convenience that a substantially constant stream of sand is being discharged into the rotatable hopper 13 by the conveyor 52. Under such conditions the initial sample and the initial residual streams and the final sample and the final residual streams are all substantially constant. Since, under the conditions outlined, the final Sample stream is substantially constant, the weights of the sand constituents on the conveyors 85 to 88 are substantially constant, any variations therein arising solely from variations in the proportions of the constituents. Any deviations in the proportions of the constituents of the final sample are measured by the scales 9! to 94, and are transmitted thereby to the master synchros S5 to 98. In turn, the master synchros 95 to 93 actuate the slave synchros 5! to 54 to vary the speeds of the motors to 48 to compensate for such deviations in the proportions of the constituents of the final sample.

In other words, let us assume that the constituent of the final sample delivered to the conveyor 85 is to be maintained at twenty-five percent of the final sample, it being necessary that the mixture delivered to the stock pile contain twenty-five percent of thi constituent. Thus, if the read-ing on the scale 9! drops to twentyfour percent (the scales 9! to 54 preferably being calibrated in percentage), the corresponding master synchro 95 causes the slave synchro 5i controlled thereby to increase the speed of the corresponding motor 45 so that the correspond-- ing conveyor 4! delivers more of the constituent in question to the conveyor 39 for mixing with the inital residue. Thus, the element just described. correct for the drop in the percentage of the constituent under consideration. The synchros 95 and 5! correct in a similar manner for an increase in the percentage of the constituent on the conveyor above the prescribed value by reducing the speed of the corresponding motor 45 to decrease the amount of this constituent which is mixed with the initial residue. The synchro sys tems and 52,9! and 53, and 98 and 55 correct for deviations in the readings of the scales 92, and. 54, respectively, from prescribed values in a similar manner.

Thus, the proportions of the stored constituents of the initial sample which are mixed with the initial residue are varied inversely with deviations in the readings of the scales 9! to 94 from prescribed values so as to maintain the scale readings substantially equal to the prescribed values. Actually, the apparatus will correct for deviations in the scale readings from the prescribed values as soon as a slight deviation occurs, the one percent deviation cited above for illustrative purposes being exaggerated. Thus, sand having proportions of constituents differing from the proportions necessary for a particular concrete, for example, will be processed by the bodiment of Fig. 1 and delivered to the stock 65 with the prescribed constituent proportions. In eifect, the proportions of the constituents of the original sand are rearranged to obtain the prescribed proportions.

As previously indicated in considering the overall operation of the embodiment illustrated in Fig. 1 of the drawings, it is necessary that the final sample stream be maintained substantially con stant so that deviations in the readings of the scales 9| to 94 reflect only deviations in the proportions of the sand constituents from prescribed values. One way of accomplishing this is to vary the split taken by the splitting means 69 in such a manner as to maintain the final sample stream substantially constant irrespective of variations in the stream of sand discharged into the apparatus by the conveyor [2. The percentage of the mixture discharged into the hopper 62 which is split off by the splitting means I59 to form the final sample stream may be varied by pivotally mounting one of the walls of the V-shaped compartment I0, e. g., the wall H0, at III so that the angle between the two walls may be varied. In the particular construction illustrated, the pivoted wall I I is shown as having a rack I I2 rigidly connected thereto, a pinion H3 driven bya reversible electric. motor H4 being meshed with the rack II2 to control the angle between the two walls of the V-shaped compartment [0. The reversible motor I I4 is actuable by a slave synchro H5 which is controlled by a master synchro IIB, the connection between the slave and master synchros being diagrammatically indicated at I I1, since it is Well known in the art. The master synchro H5 is actuable by a scale.- II8 which is operatively connected to the conveyor I2 to respond to variations in the load thereon. Thus, if the load. on the conveyor I2 increases, the scale II8 causes the master synchro IIS to actuate the slave synchro. M5, the latter energizing the reversible motor H4 in a direction to decerase the angle between the walls of the. i -shaped conipartment It. This decreases the percentage of the mixture which is split off to form the final sample stream so as to maintain the final sample stream substantially constant. The system oper ates in a similar manner in response to. adecrease in the load on the conveyor I2.

Thus, the scale H8 maintains the angle between the walls of the V-shaped compartment It! at such values as to maintain the final sample stream substantially constant. Alternatively,

the scale [I8 could be used in connection with a conveyor in other places in the system. For example, such a conveyor operatively connected to the scale 8' could be interposed between the hopper I4 and the trommel I6 so as to respond directly to variations in the. final sample stream. The scales. 9| to 94 have been referred to previously as preferably indicating percentages. This may be accomplished conveniently by designing the scale-synchro system I'I5.-I ItB' that itcontinuously adjusts the splitting means 69 to maintain the weight: rate of. flow in the final sample stream substantially equal. to, for example, 100 units for each one-half revolutionof the conveyors 85.. to. 88.v Under such. conditions, the conveyors 85 to 88, taken collectively, always. carry a weight of 100 units. If the scales; 9I. to 94 are calibrated in such units, the readings thereof Will be equal to the respective percentages This result could be attained in the same way if the scale I I8 were connected to a conveyor interposed between the hopper I4 and the, trommel I5, as suggested above.

As will be apparent, if a shortage of one of the constituents of the original sand persists-tor any length of time, the. corresponding one of the storage bins 35 to 38 would ultimately be emptied in compensating for such shortage. In order to avoid this, I provide. means for varying the proportions of the initial sample and the initial residue in response to variations the amounts of the stored constituents in the bins 35 to 38. In other words, if a prolonged shortage of one constituent tending to empty one. of the storage bins exists, such means increases the initial sample split off by the splitting means 22;.

In the particular construction illustrated, the storage bins 35, 36, 3-1 and 38 are operatively connected to scales I25, I25, I21 and I28, respectively, only two of the scales being visible'in Fig. l, but: all of them being. shown in Fig. 2'.

As in the case of the splitting means 69, the V- shaped compartment of the splitting means 22 is provided with a pivoted wall I29 for varying the angle between the walls of such compartment, the pivoted wall I29 carrying a rack I30 with which is meshed a pinion I3I driven by a reversible motor I32.

Referring now to Fig. 2 of the drawings, the

shafts of the scales I25, I23, I2? and I28 carry contact arms I35, I35, I31 and I38, respectively, and contact arms I4I, I42, I43 and I44, respectively. The contact arms I35, I36, I31 and I38 are adapted to engage stationary contacts I45, I45, I4l and ms, respectively, and the contact arms I4I, I42, 543 and I44 are adapted to engage stationary contacts l5I', I52, I53 and I54, respectively.

As will be apparent from Fig. 2 of the drawings, the switch formed by the contact arm I35 and the contact I45, the switch formed by the contact arm E35 and the contact I45, the switch formed by the contact arm i3? and the contact I47, and the switch formed by the contact arm $38 and the contact E48 are all connected in parallel across one pair of terminals of the reversible motor I52. When the amount of the constituent stored in the storage bin 35, for example, decreases below a predetermined minimum, the contact arm I35 of the corresponding scale engages the contact I45 to energize the motor I32 in the direction required to increase the angle between the walls of the V-shaped compartment 23, thereby increasing the initial samplev split oii so as to compensate for the reduction in the amount of the constituent stored in the storage bin 35. The angle between the walls of the V-shaped compartment 23 is cor-- rected in a similar manner in the event that the amount of the constituent stored in any of the other bins drops below a predetermined: minimum.

Thus, since the switches formed by the contact arms I35 to I38 and the corresponding contacts I45 to I48 are connected in parallel, a reduction in the. amount of material in any one of the storage bins 35 to 38 will result in an increase in the initial sample split off so as to maintain the supply of the corresponding constituent above a predetermined minimum- This may result in overflowing one or more of the other storage bins, such overflow being conveyed to asuitable point of disposal for other purposes.

The switch formed by the contact arm I.4I and the contact I5I, the switch formed by the con.- tact arm I42 and the contact I52, the switch formed by the contact arm I43 and the contact I53, and the switch formed by the contact arm :44 and the contact I54 are all connected in series with the other pair of terminals of the reversible motor i552. Thus, whenever the amounts of the constituents stored in all of the storage bins to 33 are above predetermined minimums, the system energizes the reversible motor in. the opposite direction to decrease the angle between the walls of the V-shaped compartment 23, thus, avoiding overflowing the storage bins under such conditions.

Thus, the system just described increases the initial sample split oii by the splitting means 22 in the response to a shortage in one of the constituents, and decreases the initial sample under other conditions, as when the constituents of the original sand are substantially in line with the constituents described.

Referring. now to Fig. 3 of the drawings. the embodiment of the apparatus of the invention illustrated therein includes a conveyor 2| 2 which discharges the sand or other material whose constituents are to be proportioned into a rotatable hopper 213 which is mounted on a shaft 2M driven in any suitable manner, the rotatable hopper having an offset spout 2l5. In order to maintain the stream of sand delivered to the rotatable hopper 2|3 substantially constant, a scraper 216 above the conveyor 2&2 is employed, any excess being scraped off into a hopper which dis charges onto a conveyor 2!!, the latter leading back to the source of the sand, for example.

Below the rotatable hopper 2l3 is a stationary hopper 2|8 having a spout 2i9 which discharges onto a conveyor 22%] leading to a stationary hopper 22!. In the stationary hopper 2! 8 is a splitting means 222 comprising a V-shaped compartment 223 which corresponds to the V-shaped compartment 23 of the previous embodiment. except that it is not adiustable. The sample split off by the splitting means 222 flows through a chute 224 to a hopper 225, the residue being discharged onto the conveyor 220.

From the hopper 225, the sample flows through a chute 226 to a separating means, illustrated as a trommel 232. The constituents of the sample which are separated from each other by the trommel 230 are discharged into chutes 23I, 222, 223, and 2-34, such constituents ultimately bein delivered to storage bins 235, 236, 23? and 228, respectively, by a conveyor system to be described hereinafter. From the bins 235, 235, 23'! and 233, the constituents stored therein are delivered to a conveyor 238 leading to the hopper 22! by conveyors 2 3i, 252, 243 and 244, respectively, which may be of the screw type. The conveyors 2 2i, 242, 223 and 224 are driven by variable-speed electric motors 245, 2 16, 241 and 2 38, respectively,

the latter being controlled by slave synchros 25!,

252, and 252, respectively. Overflow spouts 255, 256, 25? and 253 lead from the respective storage bins 235, 235, 23! and 238 to an overflow conveyor 259 leading to a suitable point of dis posal.

The hopper 22i discharges the mixture from the conveyors 22B and 239 onto a conveyor 264 leading to a stock pile 265.

Interposed between the trommel 236 and the storage bins 235, 236, 23! and 238 are conveyors 285, 285, 22! and 288, respectively. The chutes 23!, 232, 233 and 23 3 from the trommel 23c dis charge onto the conveyors 285, 286, 281 and respectively, and the latter discharge into the respective storage bins.

The conveyors 285, 286, 28'l and 288 are operatively connected to scales 29!, 292, 293 and 224- which actuate master synchros 295, 226, 227 and 293, respectively, the latter being operatively con-' nected to the slave synchros 251, 252, 253 and 254, respectively, by diagrammatically illustrated connections 3M, 3022, 323 and 304, respectively.

In operation, any deviations in the percentage of one of the constituents on the conveyors 235, 285, 287 and 282 from the value prescribed therefor results in an inverse variation in the rate at which such constituent is discharged from the corresponding one of the storage bins 235, 235, 23'! and 238. In other words, if one of the scales 29L 292, 293 and 236 indicates a constituent percentage below the value prescribed therefor, the speed of the corresponding one of the motors 265, 246, 241 and 2 53 is increased to compensate. A

deviation in the scale reading above the prescribed value results in a decrease in the speed of the corresponding motor to compensate.

Thus, in this embodiment of the invention, the compensation required for proper proportioningof the constituents is determined prior to proportioning them, whereas in the embodiment previously described, the compensation required is determined after proportioning. One advantage of the embodiment of the apparatus of the invention illustrated in Fig. 3 is that it requires fewer components. However, since this embodiment does not check the corrections it makes in the proportions of the constituents, any malfunctioning will go undetected. On the other hand, the embodiment of the apparatus of the invention which is illustrated in Figs. 1 and 2 of the drawings continuously checks the corrections which it has made in the proportions of the constituents so that any malfunctioning is immediately detected, which is an important advantage of such embodiment. Also, in the embodiment illustrated in Fig. 3, there is no compensation for prolonged shortages of one of the constituents, which is another advantage of the embodiments of Figs. 1 and 2 of the drawings.

Summarizing, both of the embodiments hereinbefore described divide the material into a sample and a residue, separate the constituents of the sample from each other, store the separated constituents of the sample independently, mix variable proportions of the stored constituents of the sample with the residue, and automatically vary the proportions of the stored constituents of the sample which are mixed with the residue inversely with deviations in the proportions of the constituents of the original material from prescribed values so as to maintain the proportions of the constituents of the resulting mixture substantially equal to the prescribed values. In the embodiment of Fig. 3 of the drawings, the proportions of the stored constituents which are employed in the mixture are varied inversely with deviations in the proportions of the constituents of the initial sample from prescribed values, whereas in the embodiment of Figs. 1 and 2 of the drawings, the proportions of the stored constituents which are employed in the mixture are varied inversely with deviations in the proportions of the constituents of the final sample from prescribed values, the final sample being taken from the mixture so that the accuracy of the proportioning is checked in the embodiment of Figs. 1 and 2 of the drawings.

Thus, the present invention provides a method of and apparatus for maintaining the proportions of the constituents of a material substantially equal to prescribed values by repr-oportioning the constituents of the original material as required, which is an important feature.

Although I have disclosed two exemplary embodiments of the invention herein and have disclosed same in connection with proportioning the constituents of a material such as sand by weight, it will be understood that various changes, modifications and substitutions may be incorporated in the embodiments disclosed and that the invention may be applied to other materials without departing from the spirit thereof.

I claim as my invention:

1. A method of regulating the proportions of the constituents of a multiple-constituent material, including the steps of: separating the constituents of the material from each'other; mixing the separated constituents together in variable proportions; and varying the proportions of the separated constituents which are mixed together as inverse functions of deviations in the proportions of the constituents of the original material from prescribed values.

2. A method of regulating the proportions of the constituents of a multiple-constituent material, including the steps of: dividing the material into a sample and a residue; separating the com stituents of said sample from each other; storing the separated constituents of said sample independently of each other; mixing variable proportions of the stored constituents of said sample with said residue; and varying the proportions of the stored constituents of said sample which are mixed with said residue inversely with deviations in the proportions of the constituents of the original material from prescribed values so as to maintain the proportions of the constituents of the resulting mixture substantially equal to said prescribed values.

3. A method of regulating the proportions of the constituents of'a multiple-constituent material, including the steps of: dividing the material into a sample and a residue; separating the constituents of said sample from each other; measuring the proportions of the separated constituents of said sample; and varying the proportions of the constituents of the material inversely with deviations in the measurements of the proportions of said sample from prescribed values.

4. A method of regulating the proportions of the constituents of a multiple-constituent material, including the steps of: dividing the material into an initial sample and an initial residue; separating the constituents of said initial sample from each other; mixing the separated constituents of said initial sample in variable proportions'with said initial residue; dividing the resulting mixture into a final sample and a final residue; separating the constituents of said final sample from each other; measuring the proportions of the separated constituents of said final sample; and varying the proportions of the separated constituents of said initial sample which are mixed with said initial residue as inverse functions of deviations in the measurements of the proportions of the separated constituents of said final sample from prescribed values so as to maintain said measurements substantially equal to said prescribed values.

5. A method of regulating the proportions of the constituents of a multiple-constituent material, including the steps of: dividing the material into an initial sample and an initial residue; separating the constituents of said initial sample from each other; storing the separated constituents of said initial sample independently of each other; mixing the stored constituents of said initial sample in variable proportions with said initial residue; dividing the resulting mixture into a final sample and a final residue; separating the constituents of said final sample from each other; measuring the proportions of the separated constituents of said final sample; and varying the proportions of the stored constituents of said initial sample which are mixed with said initial residue inversely with deviations in measurements of the proportions of the sep- 'arated constituents of said final sample from prescribed values so as to maintain said measurements substantially equal to said prescribed values.

6. A method of regulating the proportions by weight of the constituents of a multiple-constituent material, including the steps of; QiY Qi -g til the material into a sample and a residue; separating the constituents of said sample from each other; storing the separated constituents of said sample independently of each other; removing variable proportions by weight of the stored constituents of said sample from storage and mixing them with said residue; and varying the propor= tions by weight of the stored constituents of said sample which are mixed with said residue inversely with deviations in the proportions by weight of the constituents of the original material from prescribed values so as to maintain the proportions by weight of the constituents of the resulting mixture substantially equal to said prescribed values.

'7. A method of regulating the proportions of the constituents of a multiple-constituent material moving in a substantially continuous stream, including the steps of: substantially continuously dividing the stream of material into a substantially continuous sample stream and a substantially continuous residual stream; sub stantially continuously separating the constituents of said sample stream from each other; substantially continuously mixing the separated con stituents of said sample stream in variable proportions with said residual stream; and substantially continuously varying the proportions of the separated constituents of said sample stream which are mixed with said residual stream in. versely with deviations in the proportions of the constituents of the material of the original stream from prescribed values so as to maintain the proportions of the constituents of the resulting mixture substantially equal to said prescribed values.

8. A method of substantially continuously regulating the proportions by Weight of the constitu ents of a multiple-constituent material moving in a substantially continuous stream, including the steps of substantially continuously dividing the stream of material into a substantially continu ous initial sample stream and a substantially con tinuous initial residual stream; substantially con tinuously separating the constituents of saidinitial sample stream from each other; substantially continuously mixing variable proportions by weight of the separated constituents of said initial sample stream with said initial residual stream; substantially continuously dividing th resulting mixture into a substantially continuous final sample stream and a substantially contiiiiious final residual stream; substantially continu ously separating the constituents of said final sample stream from each other; substantially continuously weighing the proportions of the separated constituents of said final sample stream; and substantially continuously varying the proportions by weight of the separated constituents of said initial sample stream which are mixed with said initial residual stream inversely with deviations in the weights of the proportions of the separated constituents of said final sample stream from prescribed values so as to maintain the weights thereof substantially equal to said prescribed values.

9. In an apparatus for regulating the propor tions of the constituents of a multiple-constituent material, the combination of means for separating the constituents of the material from each other; means for mixing variable proportions of the separated constituents together; and control means for varying the proportions of the separated constituents which are mixed together as inverse functionsv of deviations in the proportions of the constituents of the original material from prescribed values.

10. In an apparatus for regulating the proportions of the constituents of a multiple-constituent material, the combination of: means for dividing the material into an initial sample and an initial residue; means for separating the constituents of said initial sample from each other; means for mixing variable proportions of the separated constituents of the initial sample with said initial residue; means for dividing the resulting mixture into a final sample and a final residue; means for separating the constituents of said final sample from each other; means for measuring the proportions of the separated constituents of said final sample; and control means operatively connected. to said measuring means and said mixing means for varying the proportions of the separated constituents of said initial sample which are xed with said initial residue inversely with deviations in the measurements of the proportions of the separated constituents of said final sample from prescribed values so as to maintain said measurements substantially equal to said prescribed values.

11. An apparatus according to claim wherein said measuring means includes scale means for measuring the proportions of the separated constituents of said final sample by weight.

12. In an apparatus for regulating the proportions of the constituents of a multiple-constituent material, the combination of: means for dividing the material into an initial sample and an initial residue; means for separating the constituents of said initial. sample from each other; means for storing the separated constituents of said initial sample independently or" each other; means for mixing variable proportions of the stored constituents of said initial sample with said initial residue; means for dividing the resulting mixture into a final sample and a final residue; means for separating the constituents of said final sample from each other; means for measuring the proportions of the separated constituents of said final sample; and control means operatively connected to said measuring means and said mixing means and actuable by said measuring means for varying the proportions of the stored constituents of said initial sample which are mixed with said initial residue inversely with deviations in the measurements of the proportions of the separated constituents of said final sample from prescribed values so as to maintain said measurements substantially equal to said prescribed values.

13. An apparatus ace rding to claim 12 wherein said measuring means includes scale means for measuring the proportions of the separated constituents of said final sample by Weight, said control means being operatively connected to said scale means to said mi g means.

14. In an apparatus for regulating the proportions by Weight of the size constituents of a material. having a plurality of constituents of different sizes, the combination of: means for dividing a substantially co tinuous stream of the material into a substantially continuous initial sample stream and. a substantially continuous initial residual stream; a plurality of storage bins; means for substantially continuously separating the size constituents of said initial sample stream from each other and for delivering them to said storage bins, respectively; a plurality of discharge means for substantially continuously discharging the stored size constituents of said initial sample stream from said storage bins, respectively, at variable rates; means for substantially continuously mixing the stored. size constituents discharged at variable rates by said discharge means with said initial. residual stream to produce a substantially continuous mixture stream; means for substantially continuously dividing said substantially continuous mixture stream into a substantially con-- tinuous final sample stream and a substantially continuous final residual stream; a p1uralitoi conveyors; means for substantially continuously separating the size constituents of said final sample stream from each other and for delivering same to said conveyors, respectively; a plurality of scales operatively connected to said conveyors, respectively, for measuring the weights of the size constituents of said final sample stream thereon, respectively; and control means operatively connecting said scales to said discharge means, respectively, for actuating said discharge means to vary the rates at which the size constituents of said initial sample stream are discharged from said storage bins inversely with deviations in the indications of said scales from prescribed values so as to maintain the indications of said scales substantially equal to said prescribed values.

1.5. In an apparatus for regulating the proportions by Weight of the size constituents of a material having a plurality of constituents of different sizes, the combination of: means for dividing a. substantially continuous stream of the material into a substantially continuous initial sample stream and a substantially continuous initial residual stream; a plurality of storage bins; means for substantially continuously separating the size constituents of said initial sample stream from each other and for delivering them to said storage bins, respectively; a plurality of variablespeed discharge means for substantially continuously discharging the stored size constituents of said initial sample stream from said storage bins, respectively, at variable rates; means for sub- 0 stantially continuously mixing the stored size constituents discharged at variable rates by said discharge means with said initial residual stream to produce a substantially continuous mixture stream; means for substantially continuously clividing said substantially continuous mixture stream into a substantially continuous final sample stream and a substantially continuous final residual stream; a plurality of conveyors; means for substantially continuously separating the size constituents of said final sample stream from each other and for delivering same to said conveyors, respectively; a plurality of scales op eratively connected to said conveyors, respectively, for measuring the weights of the size constituents of said final sample streams thereon, respectively; and control means operatively connected to said scales, respectively, and to said variable-speed discharge means, respectively, for varying the speeds of said discharge means in versely with deviations in the indications of said scales from prescribed values so as to maintain said indications of said scales substantially equal to said prescribed values.

16. An apparatus according to claim 15 wherein each of said variable-speed discharge means includes a variable-speed electric motor, said control means including means for varying the speeds of said electric motors.

17. In an apparatus for regulating the proportions by weight of the size constituents of a ma- 15 t'erial having a plurality of size constituents-the combination of: means for dividing the material into a sample and a residue; means for separating the size constituents of said sample from each. other; a plurality of variable-speed proportioning means for mixing the separated size constituents of said sample in variable proportions with said residue; and means, including a plurality of scales operatively connected to said variable-speed proportioning means, for varying the i speeds of said proportioning means inversely with deviations in the proportions by weight of the size constituents of the original material from prescribed values.

18. In an apparatus for proportioning the constituents of a multiple-constituent material, the combination of adjustable means for dividing the material into a variable sample and a variable residue; means for separating the constituents of said sample from each other; separate storage bins for the separated constituents of said sample; means for conveying the constituents from said separating means to said storage bins, respectively; means for mixing variable proportions of the stored constituents of said sample with said residue; means for varying the proportions of the stored constituents of said sample which are mixed with said residue inversely with deviations the proportions of the constituents of the oriai nal material from prescribed values so as to maintain the proportions of the constituents of the resulting mixture substantially canal to said prescribed values; and means responsive to the amounts of the stored constituents in said storage bins and operatively connected to said adjustable dividing means for regulating the proportions of said sample and said residue.

19. In an apparatus for regulating the propertions of the constituents of a multiple-constituent material, the constituents being separated from each other, the combination of: means for mixing variable proportions of the separated constituents together; and control means responsive to the proportions of the mixed constituents and opera-- tively connected to said mixing means for Varying the proportions of the separated constituents which are mixed together as inverse functions of deviations in the proportions of the constituents from prescribed values.

20. In an apparatus for regulating the proportions of the constituents of a multiple-constituent material, the constituents being separated from each other, the combination of: means for mixing variable proportions of the separated constituents together; means for dividing the resultant mixture into a sample and a residue; means for separating the constituents of the sample from each other; means for measuring the proportions of the separated constituents of the sample; and control means operatively connected to said measuring means and said mixing means for varying the proportions of the original separated constituents which are mixed together inversely with deviations in the measurements of the proportions of the separated constituents of the sample from prescribed values so as to maintain the measurements substantially equal to said prescribed values.

21. In an apparatus for regulating the proportions of the constituents of a multiple-constituent material, the constituents being separated from each other, the combination of: proportioning means for mixin variable proportions of the separated constituents together to obtain a mixture thereof; splitting means receiving the mixture from said proportioning means for diViClil'lgthe; mixture into a sample and a residue; means for separating the constituents of the sample from each other; means for conveying the sample tosaid separating means; receptacles for the respec-. tive separated constituents derived from the sample; means for conveying the separated constituents derived from the sample from said separating means to said receptacles, respectively; quantity responsive means including indicating devices operatively connected to said receptacles and responsive to the quantities of the materials therein; and control means operatively connected to said indicating devices and to said proportioning means for varying the proportions of the originalseparated constituents which are mixed together inversely with deviations in the measurements of the proportions of the separated constituents of the sample from prescribed values so as to maintain said measurements substantially equal to said prescribed values.

22. An apparatus as defined in claim 21 wherein said proportioning means includes variablerate feeding means for the respective original separated constituents, and wherein said control means includes servo-mechanisms connecting said indicating devices to said variable-rate feeding means.

23. In an apparatus for regulating the proportions of the constituents of a multiple-constituent material, the constituents being separated from each other, the combination of: storage bins for the respective constituents; proportioning means for mixing variable proportions of the separated constituents together, including variable-rate feeding means communicating with said storage bins, respectively, for feeding the stored constituents therefrom at variable rates; and control means responsive to the proportions of the mixed constituents and operatively connected to said variable-rate feedin means for varying the feeding rates of the stored constituents as inverse functions of deviations in the proportions of the constituents from prescribed values.

24. In an apparatus for regulating the proportions of the constituents of a multiple-constituent material, the constituents being separated from each other, the combination of: storage bins for the respective constituents; proportioning means for mixing variable proportions of the separated constituents together, including variable-rate feeding means communicating with said storage bins, respectively, for feeding the stored constituents therefrom at variable rates; means receiving at least a sample of the mixture produced by said proportioning means for separatin the constituents of the sample from each other; measuring devices receiving the separated constituents of the sample from the separating means for measuring the proportions of the constituents of the sample; and control means operatively connected to said measuring devices and said variable-rate feeding means for varying the feeding rates of the stored constituents as inverse functions of deviations in the proportions of the constituents from prescribed values.

WALTER E. SAXE.

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

UNITED STATES PATENTS Number Name Date 2,285,765 Carswell June 9, 1942 2,344,228 Barber Mar. 14, 1944

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