US2769622A - Mixer - Google Patents

Description

, T. JENSEN Nov. 6, 1956 MIXER 3 Sheets-Sheet 1 Filed Aug. 20, 1952 mm TI 93 m INVENTOR fholfmqd' Jensen M, W

BY M a? ATTOR Nov. 6, 1 956 Filed Aug. 20. 1952 3 Sheets-Sheet 2 WW //6 LLU INVENTOR T/o rmod Jensen BY glam ATTO R N Nov. 6, 1956 T. JENSEN 2,769,622

MIXER Filed Aug. 20; 1952 3 Sheets-Sheet 5 INVENTOR Thai-m ad J6 nsen ATTOR F s United States Patent MIXER Thormod Jensen, Laurelton, N. Y., assignor to American Machine and Foundry Company, a corporation of New Jersey Application August 20, 1952, Serial No. 305,333 11 Claims. (Cl. 259-8) This invention relates to an improved mixing machine and process having the purpose of initially or further mixing and refining a pre-mixed and pre-blended material or medium in order to produce a final mix of extremely high quality and of uniform and desirable texture.

The invention, and the illustrative apparatus and the process, are calculated to achieve the desired results, and involve particularly a new mixing head. This invention is related to that of my copending application Serial No. 239,294, filed July 36, 1951, now Patent No. 2,687,877, and in general the present structure is identical therewith except where otherwise specifically stated.

The machine and process of the present invention are adaptable to various types of slurries and mixes such as cake batters, toppings, spreads, primary bread ingredients, etc., and, additionally the invention is adaptable to chemical processing, such as mixing paints, and in latex work involving the formation of foam rubber for pillows, etc., and a thoroughly uniform mixing is obtained. For processing involving the forming of foam from a liquid, the air is preferably added to the stream of liquid prior to entry of the liquid to the treating zone. In latex work the zinc and gel are injected at the proper places in the process, and the pre-blended liquid latex is foamed to a high degree and with a simplicity never previously obtained.

In accordance with the foregoing, an object of the invention is to provide an improved mixing device and process wherein the mix (which may include air) is supplied under pressure to a mixing head under controlled conditions, and a thoroughly uniform mixing is obtained and the air slugs or pockets are broken up into extremely small bubbles; and the mix is then discharged in such a way that the bubbles are not broken but they expand so as to form a very high quality foam. A further object is to provide a new mixing head of improved and simplified construction. Another object of the invention is to'provide for the above with a sturdy and simple. construction having a rotor and stator with mutually cooperating parts. Another object of the invention is to provide an improved mixing machine of the type as set forth above, which is readily cleanable, and wherein the shaft is journalled in bearing supports with a shaft seal. A still further object is to provide for the above with apparatus which is practical in construction, efiicient in use, and is adaptable to meet the particular problems encountered in the many fields where it has application.

Further objects and numerous of the advantages of the invention will become apparent from the following detailed description and annexed drawings wherein:

Figure 1 is a general perspective view of a complete machine constituting one embodiment of the invention;

"Figure 2 is a front elevation of the machine partly broken away to illustrate the general arrangement of the mechanism;

Figure 3 is a partially schematic sectionalview of a preferred form of mixing head according to the present invention;. H

ice

Figure 4 is a fragmentary plan View of the inside of the stator showing the transverse grooves;

Figure 5 is a fragmentary perspective view of another form of mixing head rotor; and

Figure 6 is a view similar to Figure 5 of another form of rotor.

Referring now to Figure 1 of the drawings, numeral 10 indicates generally the case or housing of the machine which is mounted on casters 12 so that it can be freely moved about. On the front of the housing are hand wheels 14 and 16, the purpose of which, as described in my above-identified copending application, is to adjust the speed of mixing and the pressure of the pre-blended mix being fed to the mixing head. Start and stop switches 18 and 20 are also on the front panel of the housing 10 for controlling the operation of the motors driving the pump and the mixing machine, as described in said application. Numeral 24 indicates the mixing head on the top of the machine, and the blended mix or material to be mixed is fed thereto from a supply tank, not shown. The mix may be supplied directly from a tank or it may be drawn from the tank by a pump and then flow through a line to which there is connected an air or gas injecting and metering device 28 which is of a known type and need not be described in detail. The metering device 28 has a manual adjustment 31 and associated with it is a pressure gauge 32 to indicate the pressure of the gas being supplied to the mix through a valve 33. The mix proceeds through a pipe 34 to the mixing head and the temperature at the mixing head is indicated by a ther mometer. A discharge hue from the mixing head is connected to a depositer as will be described in detail herein. A pair of tachometers 54 and 56 indicate the respective speeds of the fluid pump and the rotor of head 24.

Referring now to Figure 2 of the drawings, the housing 10 has upright frame members 44 and transverse frame member 45 as well as transverse members 48, 50, and 52. As previously described, the mixing head 24 is mounted above the top of the housing, and supported upon the vertical shaft 58 is the rotor of the mixing head. It should be noted however that the mixing head does not have to be mounted on the top of the housing 10 nor in the vertical position shown but might be mounted on the side of the housing with its axis horizontal or with the axis vertical but the small end on the bottom. Beneath the main head the shaft passes through a bearing member 69 mounted on transverse member 48 and the shaft is also journalled in a bearing mounted in pillow block 62 mounted on the transverse member 52. Shaft 58 is coupled at its lower end through a coupling 64 to a speed reduction mechanism 66 which is driven by an electric motor 68. The arrangements of the drives for the mixing head 24 and fluid pump are shown and described in greater detail in my above copending application.

Referring to Figure 3, the circular rotor (of the mixing head 24 of Figures 1 and 2) is fi'oatingly mounted on the drive shaft 58 and has its hub keyed to shaft 58 by a taper pin 192 which lies in slot 163. The Web rests on a bottom sleeve 164 which in turn rests upon 'a spring ring or retainer 106 carried by the shaft in an annular slot. The rotor 10% is retained in position on shaft 58 with a minimum of play by a top retainer cap 198. The rotor itself is of a generally frusto-conical shape with a series of concave annular grooves or rings 110 of increasing diameter from top to bottom out into the surface of the rotor. Positioned in these annular rings 11!) are six coil springs 109, 111, 112, 113, 115, and'117, each of which is connected at its ends and is an annulus. Each of these springs fits into the respective annular concave groove 110 of the rotor. The crosssectional diameter of the springs is such that they nest in their grooves and extend outwardly ofthe surface of the rotor pproximately one-half their circular cross- I section. V V V The mixing head has a stator 114, which is mounted over'the assembled rotor and springs and is' a hollow, generally frusto-conical shell clamped by. bolts -118-and nuts-12.9 on a'base plate 116 which is attached to the machine frame' As maybe seen in Figuresjl and 2, handles 122 are provided on the two sidesof the stator for easy handling during assembly and disassembly'of the mixing head structure. V

. The inside of the stator 114 has a series of concave.

annular groovesor rings 124 cut into the inner surface thereof, corresponding to those on the rotor and enclosing.

'Stator .114 is closed'at the top by a removable plate 131? having a gasket 131, and at the bottom a gasket 133 seals the. stator at the base plate 116. There is' also a fiuid seal 132 about shaft 58, which is formed by 136, which in turn is held in place by a ring nut 138 threaded onto a neck 140 mounted'on the base plate 116.

In operation, the fluid, for example a mix which is to be foamed and contains a substantial amount of air, enters through the pipe 126 undera pressure such'as several atmospheres; Pipe 126'delivers themix into the top space or inlet chamber 142 about the top spring 109. The projecting shoulder 146 on the stator acts with the duce the'cutting and mixing by the'springs, and would,

materially reduce the effectiveness and efficiency of the apparatus. To prevent such action, the inner stator surface of each groove 124 (see Figure 4), has arrow of 1 small arcuate grooves 148 which extend somewhat transversely of the path which the mix would tend to follow. In this embodiment, thegrooves are spaced circumferentially of the rotor axis, one-half inch apart, and with a'width of one-quarter of an inch and a radiusof one-' eighth of an inch. These grooves'are. at an angle to the transverse dimension of grooves 124 and are produced upon a standard milling machine, with the spindle extending in from what is the bottom of the stator. The

' surface friction of the stator to the mix, together with the 1 spring 109, and it passes into and fills thechamber 142.

chevron rings 134 hel'd'by a clamping bearing collar rotor somewhat as a restricting collar or bottleneck 147,

. 'so that the fluid tends to fill the entire inlet. chamber inbetween the portions of the spring. Also the rotating spring 109 picks up the fluid between its successive turns or wire elements, which cut or chop the fluid stream into small segments. Spring 109 also tends-to carry the'fluid around the entire circular path infchamber 142. The

i fluid or mix' then flows evenly down through bottleneck 147 and is projected in an annular stream against the toprapidly rotating spring 111. The individual turns of this spring cut this annular stream with impacting actions, and all individual particles of the mix, including the bubbles of air or other gas, are broken, so as to thoroughly mix the fluid and foam it. The flow continues downwardly and the fluid passes out the bottom side of spring 111 and again encounters another bottleneck which insures a uniform distribution of the fluid.

The annular stream of fluid thus formed by this bottleneck is directed against, and impacted bythe individual turns of spring 112,.where the mixing and-foaming action is furthered. Similar and further actions are produced by the other springs. Furthermore, each spring'has a larger diameter and a larger working zone than the next spring above it, so that if the volume of the fluid were constant, the flow rate would be reduced. In addition, the increased diameter gives a correspondingly increased speed of movement for the spring, and this increases the forces of impact, and the cutting action. 1 Hence, the reduction in the sizes of the particles and gas cells is accompaniedby an increase in the force and speed of the impact action, and by a decrease in the general downward rate of flow.

With certain fluids the tendency for the springs to carry the mix around with them tendsto cause the .fluid.

to rotate with the springs. Hence, under the influence of the centrifugal forces present, the fluid would tend to flow outwardly and down the surface of the .stator through the annular clearance spaces. This would reinterruption of flow caused by these transverse grooves, prevents the fluid from rotating with the rotor. With certain of the heavier or more viscous fluids, these grooves 148may be omitted entirely or replaced witha knurled surface, depending upon the amount of friction necessary to' prevent the rotation ofthe fluid;

Referring again to the operation, as the fluid enters the inlet 126 it is initiallycut into segments by the first The fluid then under the influence of gravity and the pressure of the system, flows downwardly and outwardly through the annular bottleneck 147. between the rotor and the stator, and thence on down past the other springs. Since the-fluid is held relatively stationary compared to the rotor by theaction'of the small transverse groovesfl 148, the fluid is cut by the rotating springs as it descendsv and successively greater numbers of smaller and smaller gas .cells are formed until the desired degree of foaming.

of thematerial is obtained and the very desirable microscopic cellular structure is achieved.

At the bottom of the rotor, the foamed mix enters'the annular space 150m which are disposed a plurality of These 'arms 152 are. flat vanes' blending arms- 152. mounted radially about the bottom surface of the rotor 10%) and they preventthe stagnation or settling of the fluid inthe space. around and below the rotor-at the outlet; 128. These radially disposed blades rotate'the fluid in the bottom annular space 150 land the centrifugal forces created circulate the fluid from the center towards the outside, and bring the liquid around to the outletpipe 128 so that there isa flow of fluid at'all points and toward:

the outlet.

l'The'fluid is discharged to molds at atmospheric. pres-j. sure from outlet 128, through a discharge pipe 164, which has a length of from 10 to 15' feet, with a diameter: of. 1 from one-'half'of an inch to one inch. This "length and. size of pipe causes a reduction in fluid pressure and the small air or gas bubbles which have been under pressure. are expanded, thus greatly augmenting the foaming eifecta By reducing the pressure in this way, a pressure relief valve is not required, the internal friction'and resistance to flow of the pipe being suflicient to dissipate the pres-,

sure and allow a properdis'charge. 'The eliminationof this valveprevents the collapsing of the foam encountered in passing-a mixture such as described through'such a. valve. The relative diameters of the inlet and discharge; pipes are chosen in accordance with the amount and pressure of the air or otherv gas introduced into the fluid so 7 that, the outlet pipe will accommodate the increased vol- 7 time as the pressure drops toward the discharge pointand thedesired degree of foamingwill be obtained. V

Since this device may often be used for mixing .fluids.

wherein the temperature of the fluid is an importantfao tor .in the final characteristics of the product, the mixing head is provided with a temperature regulating system- 166. This system includes a plurality of evaporator or 1 cooling coils 168 surrounding the stator, and .in intimate contact with the outer surface thereof. These coils-tare. enclosed by a -cover,170 are connected to a refrigeration system having a motor-compressor 172, a condenser .1724, j a receiver 176, an expansion valve 178 having a bulb 180,.

and controls for the system. This system may be operated to prevent the fluid from heating at all as it passes through the mixing head or to cool it to a desired temperature. When a small amount of cooling is suflicient, the coils 168 may be connected to any conveniently available source or cool liquid such as ice water.

While the direction of flow of the fluid through the mixing head has been described as from top to bottom, it is to be understood that with certain mixes, it may be desirable to reverse the direction of flow. This reversal of flow is used particularly where it is not desired to foam the fluid or mix. However, the direction of flow shown and described is quite advantageous where it is desired to foam and the fluid since the mixture of air and fluid may be introduced under pressure at the top and allowed to expand and foam as it flows downwardly into the gradually increasing space due to the increase of volume of the annular grooves as the diameter thereof increases.

There is thus provided a mixing apparatus of a simplified and cheaper construction which effects a breaking down of the larger particles into smaller particles, such, it has been found, that this particular arrangement will produce particles of microscopic structure with the desired characteristics of texture and cellular structure with greatly increased efficiency. In addition, with a head of this type, very little heating of the fluid is encountered as it passes through the mixing head, as compared with heads heretofore known and used.

Referring now to Figure 5, there is shown another embodiment of the invention, wherein the annular grooves and springs of the rotor of Figures 1 to 4 are replaced by a plurality of relatively narrow and thin strips 154 of sheet material. Each strip 154 has a series of arcuate bridge-like spans 156 spaced therealong. The arcuate spans 156 are illustratively the same radius as the springs of the embodiment of Figure 3, and there are six arcuate spans. These strips are equally spaced about the surface of the cone-shaped rotor, and are fastened thereto by screws 155 to provide a mixing rotor which gives the action desired. The number of these strips depends upon the conditions of operation and nature of the mix, and may be from eight to more than twenty. In Figure 6 there is shown another embodiment of the invention, wherein the strips of Figure 5 are replaced by die castings having a base strip 160 and six arcuate spans 161 integrally formed thereon. These castings are then mounted in peripheral axial grooves 163 in the surface of the cone shape rotor to give the desired mixing action. The rotors of Figures 5 and 6 are generally used for heavier or more viscous mixes, and where the action of the embodiment of Figures 1 to 4 is too severe.

From the foregoing those skilled in the art will observe that I have provided a very effective machine and process whereby various mixes such as batters, etc., can be mixed, kneaded, blended and further refined to an extremely desirable texture and composition superior to any mixes that have previously been known in the past. The refined mixes can be made to yield a greater volume per pound than has been possible in heretofore known refining methods and apparatus, and this is particularly true in connection with cake batters when the cake goes into the oven immediately following refining. The arrangement of the parts is such as to permit a ready disassembly for cleaning, which is desirable and even may be required by law after the processing of every batch period of use.

The foregoing is illustrative of preferred embodiments of my invention and it is to be understood that various alternatives and modifications may be adopted by those skilled in the art, and it is intended that such alternatives and modifications be encompassed within the scope of the claims appended hereto.

I claim:

1. In a mixing device of the character described, the

combination of a stator presenting a stationary annular frusto-conical confining wall, and a rotor presenting an annular confining wall mating with said stationary confining wall and forming therewith a generally frustoconical space, said rotor having a plurality of mixing elements thereon formed by coil springs, each of which is an annulus and presents a substantially arcuate mixing portion extending radially toward said annular confining wall.

2. A mixing device as described in claim 1, wherein said confining walls define a plurality of mixing zones, and wherein an annular restriction to flow is provided between each two of a plurality of mixing zones.

3. A mixing device as described in claim 1, wherein said stator includes cover means providing a closed chamber around said rotor, and inlet and outlet ports for the flow of material being mixed.

4. A mixing device as described in claim 3, wherein said inlet and outlet ports are formed by radially extending pipes, and shaft means supporting said rotor.

5. A mixing device as described in claim 1, wherein said confining walls are substantially frusto-conical, and wherein said coil springs are of different diameters.

6. A mixing device as described in claim 1, which includes driving means, means to control the driving speed, and means to supply fluid to be mixed under a predetermined and variable pressure.

7. A mixing device as described in claim 6, which includes means to add gas to a liquid which is being mixed in a mixing zone in said space thereby to foam the liquid, and wherein the mixing zone is frusto-conical, and the liquid is supplied radially to the smaller radius end of the mixing zone.

8. Apparatus as described in claim 7, wherein said stator has recesses transverse of the normal rotary flow along said stationary annular confining wall, whereby rotation of the fluid is restrained.

9. In a mixing device of the character described, the combination of, a stator presenting a stationary annular frusto-conical confining wall having annular grooves therein which are separated by annular ribs, and a rotor presenting an annular confining wall generally parallel to the plane of the surfaces presented by said ribs and forming therewith a generally frusto-conical mixing space, said rotor having a plurality of mixing elements thereon, each presenting a substantially semi-circular mixing portion with its axis substantially tangential with respect to said confining wall of said rotor, each of said mixing portions projecting beyond said confining wall of said rotor and extending into one of said annular grooves in said confining wall of said stator.

10. A mixing device as described in claim 9 wherein said mixing elements are in the form of individual semicircular portions rigidly mounted upon said rotor.

11. A mixing device as described in claim 10 wherein said mixing elements are in rows parallel to said rotor surface and each row is formed by a rigid bar having edge portions.

References Cited in the file of this patent UNITED STATES PATENTS 439,485 Dieseldorff Oct. 28, 1890 1,466,639 Browne Aug. 28, 1923 1,874,079 Black Aug. 30, 1932 2,078,065 De Bethune Apr. 20, 1937 2,132,364 Thompson Oct. 4, 1938 2,211,387 Routh Aug. 13, 1940 2,295,121 McLean Sept. 8, 1942 2,577,095 Walker Dec. 4, 1951 FOREIGN PATENTS 129,757 Great Britain Dec. 11, 1918

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