US2578118A - Apparatus for measuring apparent density of flour, meal, and the like - Google Patents

Description

Dec. 11, R J, OOD

APPARATUS FOR MEASURING APPARENT DENSITY OF FLOUR, MEAL, AND THE LIKE 2 SHEETS-SHEET 1 Filed March 3, 1947 F16. 1 INVENTOR.

PAUL J. W000 M a QZ'u/uw'ii/00ml ATTOBNE vs Dec. 11, 1951. P J wQoD 2,578,118

APPARATUS FOR MEASURING APPARENT DENSITY OF FLOUR, MEAL, AND THE LIKE Filed March a, 1947 2 SHEETS-SHEET 2 INDIcA TING v f Rrcoznnve -70 H o L INDICA 711m 74 AMPLIFIER. I

D. C. METER FIG. 5 I

IN VEN TOR. PAUL J W000 BY amt/M qiwwiiwvd ATTORNEYJ upon the moisture content of the flour. common practice when the miller is attempting Patented Dec. 11, 1951 UNITED STATES PATENT OFFICE APPARATUS FOR MEASURING APPARENT DENSITY OF FLOUR, MEAL, AND THE LIKE Paul J W Danville, Il

Applicaticn March 3, 1947, Serial No. 732,030

2 Claims. (01. 7332) particularly useful in the case of flours made by first flaking grain and then grinding it. In this process, the weight of the finished flour depends upon the treatment received during flaking, during which operation the grain cells are disrupted to varying extents depending on the temperature and the adjustment of the flaking rolls.

It is common practice to control the performance of milling machines and the properties of the finished product using the relative bulk density as the control factor. Thus, for example, corn or wheat flour produced for various domestic and industrial purposes is milled, and the miller watches the operation of the machines byoccasionally taking a sample from the flowing stream of flour produced, passing it through a sifter into a quart can, levelling the can by drawing a knife or blade across the top, and then weighing the contents. which has 6, 8, 10, 12 and 14 ounces of flour per quart measure. The test is inaccurate and may vary plus or minus 0.25 ounce more or less due 'to manipulation of the sifter. For example, the

rate at which the sifter is operated will vary the bulk density substantially because of the fact that more or less air is incorporated into the powder. Furthermore, the bulk density may vary as much as l to 2 ounces per quart because the miller cannot keep up with changes in bulk density due to various operating factors which he must control. The bulk density not only depends upon particle size but also to some extent It is to produce-flour of a given bulk density, and when the bulk density varies outside the accepted limits, to divert the stream of flour toa scrap bin. Under present conditions it is a diflicult problem to blend back the scrap which maybe eitherover weight or under weight. The present invention makes it possible to automatically control the milling equipment so as to take care of weight differences, and this means that the scrap can be readily blended back in the Flour for various purposes is sold dampening device.

proper proportions to produce a flour of the desired bulk density.

In one specific embodiment the present invention comprises a means for withdrawing an 3 1i!- quot portion of. flour continuously from a production stream, passing it through a mechanically operated sifter. and diverting a stream thereof upon a displacement cone disposed upon a balanced arm and determining the extent of displacement of the arm due to the ialling stream of flour.

In a further embodiment the invention comprises the device just described coupled with an automatic indicating meter and/ or control means for changing the setting of milling equipment to control the weight of flour produced.

The invention is illustrated in the accompanying drawings of which Figure 1 is a perspective View of one embodiment partially in section. Figure 2 is a view in elevation showing a light source and photoelectric means and with part of the mechanism encased. Figure 3 is a detail of an automatic tilting device for the spout or chute. Figure 4 is a detail of a knife edge and Fi ure 5 i a d a r m at c view of the device showing the arrangement of a phototube, flag, amplifier and indicating and recording meter. Figure 6 is a cross section of one modificat on of he b .Reierring to F gure t e m st of our from the milling equipment passes through duct 10. On the under side of this duct is an opening II and a valve gate 12 mounted on a bracket l3. The valve may be of any suitable type but is illustrated as a sliding gate. In the gate 12 is a notch 14 located in such a manner as to slide around the shaft 15 of the agitator which is driven by motor [-6. The agitator may have one or more paddles l'l throughout its length, and on the end is a beater I8 similar to the beater of a conventional flour sifter. Duct I9 is attac ed by any suitable means to duct [0 in such a way that flour passing through the hole I I will fall int t duct. nly a part of the flour i thu withdrawn, the remainder passing down duct [0. A supporting framework 20 may provide additional support for the assembled device. In a flanged throat section 2| is mounted the beater I8. This throat section may be reduced throughout its length to conform to the diameter of the heater [8. At the lower end is a flange 22 in which is mounted a screen 23 of concave shape conforming to the contour of the lower portion of beater 18. This is similar to a conventional flour sitter arrangement. Attached to flange 22 is a tapered duct 24 open at its lower end into a chute which is pivotally mounted as hereinafter described. As an alternative to this arrangement, a ibrator 26 (see Figure 2) may be I attached to the side of duct [9 replacing the motor, motor shaft and beater. This vibrator may be of the type Model V-4, sold by the Syntron Company of Homer City, Pennsylvania, which comprises a leaf spring, an armature, a magnetic coil, a magnet yoke, a suitable-housing, and means for attaching the vibrator to the duct.

The rapid vibration of this device causes the duct 19 to vibrate and this in turn causes the flour introduced into the duct I9 through the opening I l in duct I6 to be sifted through screen 23.

The chute 25 is pivotally mounted on a shaft 2'! which in turn is mounted on supporting frame 20. The purpose of chute 25 is to direct the sifted stream of flour downwardly upon bob 28.- This bob comprises a cylindrical body 29 and a tapered cone-shaped head 36. The cone-shaped head flares from the point downwardly and outwardly in a concave manner. The base of the cone is larger in diameter than the diameter of the cylindrical body 29. The tapered bob is supported by means of yoke 31 upon the upturned pointed prongs of which the bob isbalanced. This may be done, for example, by the. means illustrated in Figure 7, the points resting in depressions 33 in the under side of the flange 32. The bob is thus balanced so that it is always in a vertical position as arm 36 swings. Other suitable means of doing this may be. used.

The yoke 3| is located at one end of a balance rod 36. The balance rod may suitably pass through a block 31. Knife edges 33 extend laterally from each side of the block. These knife edges may be of hardened polished steel or of agate or other suitable material. The knife edges rest in V blocks 38, also of hardened steel, agate or the like. The V blocks are supported upon posts 4| which in turn are mounted upon a suitable framework 42. The mechanism may -be enclosed in housing 35. Attached to the cross member 40 is a suitable device for limiting the vertical movement of the rod 36. This comprises stops 43 and 44 attached by any suitable means such as screw 45 to the cross member 46. In the operation of the mechanism, vertical movement in either direction of sufficient magnitude for the rod 36 to strike either stop 43 or indicates that radical adjustment of the milling equipment is necessary. If desired an alarm system may be actuated when this occurs, to :warn the miller. It is desirable to limit the magnitude of swing of rod 36 because the knife edge balance and the other adjustment means to be described are likely to be thrown out of adjustment and possibly damaged if the extent of movement becomes too great.

Chain 46 is attached to rod 36 by means of adjustable bracket'or clamp 41. The opposite end of chain 46 is looped over bracket 48 which may be attached to the cross member 46. The bracket 48 is preferably a rod although it may be a loop or hook into which the links of chain 46 may be hooked. The length of the chain forming the major loop between the brackets 41 and 48 will depend upon the extent of movement of rod 36. For example, when heavier flour is used the loop may be larger than when lighter flour is used. This not only tends to dampen the swing but more or less offsets the balancing efiect of the flowing stream of powder over the bob 28. Attached to the block 3'! is a threaded side arm 49 upon which a counter weight 50 is screwed to permit fine adjustment.

Also attached to the block 3'! is an arm 5| at one end of which is pivoted a plunger rod 52. On the lower end of plunger 52 is a disc 53. The rod passes through an opening in the cover 54 of vessel 55 and the disc 53 fits inside of it. A suitable liquid such as oil having the necessary viscosity, is placed in this vessel. There is sufficient clearance around the edges of the disc .53 so that the oil can flow around it as the disc moves up and down in the liquid. Alternatively,

perforations may be made in the disc 53. The purpose of this is to dampen the swing of the rod 36 due to minor momentary changes in the rate of flow of powder from chute 25. This tends to give a more constant reading on the indicator and to prevent the needle of an indicator from moving violently so that an accurate reading can be made. It is also necessary that the swing of arm 36 be dampened sufiiciently that a small or momentary change in the rate of flow or the density of the flowing powder will not upset any control mechanism which is actuated by the device being described.

In order to compensate for the change in position of bob 28 and to'keep the flow of powder directed at all times upon the top of the bob, a

pivotal connection is made between the chute 25 and the rod 36. This is done by means of lever arms 56 attached to the chute 25. The yoke 51 is pivotally connected with arms 56, The yoke 51 pivoted to arms 56 is joined to a second and smaller yoke 58. This is pivoted on a fitting 59 which slips over the rod 36 and may be setat a selected point along its length by means of set screw 66. Extending from each side of this fitting 59 is a pair of pivot arms 6! which are pivotally mounted in the arms of yoke 58 and retained by discs 34. Thus, a linkage is made between the rod 36 and the arm 56. As the bob 28 moves downwardly and inwardly it of course follows an are which is related to the distance from the knife edge to the point of the bob. At the same time the link just described causes the spout 25 to move correspondingly so that the powder flowing out of spout 25 is always directed immediately upon the cone 30 of bob 28. In this way the effect of the falling powder does not change except as a result of a change in its density. In a like manner, as the powder becomes lighter and the bob 28 moves upwardly, the nose of the spout 25 is lifted and the falling stream of powder continues to be directed upon the bob.

For some purposes, when the weight of processed flour is substantially constant, the powder may drop directly on the bob from the outlet of tapered member 24 which is appropriately located over the bob. The chute 25 is thus eliminated.

In Figure 4 is a modification of a dampening device which may be employed instead of the oil cylinder previously described. In this case a rod 66 may depend from the bottom of block 31. This may have an adjustable weight 61 which may be moved up and down to produce a dampening effect due to its pendulum action. Thus, by raising the weight 61 the dampening effect becomes less and the tendency of rod 36 to oscillate becomes greater. By lowering the weight 6! the dampening effect is increased and the tend ency of rod 36 to oscillate is reduced.

Immediately below the bob 28 is a hopper 68 having a .duct.69. leading therefromtothe. storage bin. Alternatively, this duct 69 may lead back into duct In at a lower level.

Attached to the end of rod 36 opposite that on which the bob 28 is placed, is a flag 62 mountable for adjustment by means of bracket 63. Positioned on one side of the flag is a light source 64 for casting a beam of light to a photoelectric tube or cell 65. The flag is 50 positioned that it intercepts at least a part of the beam of light before it strikes the phototube. The response of the tube depends upon the position of the flag relative to the phototube and the beam of light. Instead of a single phototube having a long cathode it is possible to employ a series of phototubes that are connected with an electrical circuit to bring about the desired response. Whether one or more tubes is used is dependent to some extent upon whether an indicating device only is employed or-whether both an indicator and a controller are used.

In Figure 5 is illustrated a simple control device, it being represented diagrammatically. As indicated the flag 62 is positioned in front of the cathode of phototube 65. The cathode is illustrated as partially shielded with a mask having an opening to limit the amount of cathode exposed to light. Appropriate leads connect the tube with an indicating amplifier H and thence to a direct current meter 12 having an indicating hand I3 and a scale 14. As the flour or other comminuted solid falls from the hopper on to the bob 28, it causes a deflection of the arm 36, this deflection depending upon the apparent bulk density of the flour. As long as the density does not change substantially the amount of displacement will be more or less constant. By varying the weight on the end of rod 36, for example, by changing the length of the loop of chain 46, the same range of displacement may be used to indicate different weights of flour. Thus, for example, if 10 ounce flour is to be manufactured, the weight on the arm is adjusted so that a certain reading will appear on the scale 14 of the indicator. This, for example, can be the zero point and may be located directly in the middle of the scale. If the flour becomes heavier the needle will be displaced in one direction, while if it becomes lighter it will be displaced in the opposite direction. The miller, by watching the position of the needle, can tell when any substantial change occurs in the weight of the flour. This effect is obtained due to the fact that the flag covers a greater amount of the cathode when the flour becomes heavier and a lesser amount of the cathode when the flour becomes lighter. The conductivity of the tube, and consequently the reading on the meter, depends upon the amount of light received by the cathode. Since a bulb or other light source of constant light value is used, the conductivity will depend upon the area of the cathode that is exposed to light. Since with the heavier flour the arm 36 is displaced in a downward direction, the flag will cover a larger comparative area of the cathode and the phototube Will conduct less current so that the indicating needle will be displaced generally to the left, indicating the flow of a smaller amount of current. If, on the other hand, the density of the flour becomes less so that the bob 28 tends to rise, the flag drops, exposing a larger area of the cathode, and a greater amount of current is transmitted so that the indicating needle will be displaced to the right. The miller, observing this, knows that the flour is too light and can make manual adjustment of the milling equipment to correct this. If the miller desires to produce a heavier grade of flour he changes the weight on the end of rod 36, using a weight which has previously been correlated with known flour weights, giving a needle setting of whatever value he may select. The operation is then begun and he proceeds as previously described. Alternatively, the same setting can be used, and a different reference point selected on the indicator.

The device may also be used to indicate and control the viscosity of fluids, for example, paper pulp, emulsions, etc.

Having described my invention, I do not intend to be limited to the exact mechanism or modifications illustrated.

I claim as my invention:

1. An apparatus for continuously determining the apparent density of comminuted solids flowing through a duct which comprises means for directing a free falling stream of said solids through a test zone, a bob of smaller cross section than the falling stream, a lever mounted for limited pivotal movement at a point intermediate its length, said bob being suspended on one arm of a lever centrally of the path of fall of said test stream in such a manner that the powder falls on and around it, the other arm of said lever comprising adjustable counterbalancing means, and means for indicating the degree of deflection of said bob caused by said test stream of solids striking it, said means for directing said stream comprising a variable spout linked with the lever so that movement of the bob causes corresponding movement of the spout whereby the stream of solids is continually directed upon the bob.

2. The apparatus of claim 1 wherein the bob comprises a cylindrical body section, a cone shaped head section, said head section tapering from a point to a flanged portion of greater diameter than the cylindrical body, the face of the cone tapering downwardly and outwardly in a concave manner.

PAUL J. WOOD.

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

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