US2843169A - Laboratory mill for comminuting materials to fine particle size - Google Patents

Description

July 15, 1958 F. w. STEIN LABORATORY MILL FOR COMMINUTING MATERIALS TO FINE PARTICLE SIZE Filed Aug 4, 1954 INVENTOR. Fx'eder/ak I44 fife/x7 United States Patent LABORATORY MILL FOR COMMINUTING MATERIALS TO FINE PARTICLE SIZE Frederick w. Stein, Atchison, Karts.

Application August 4, 1954, Serial No. 447,377

9 Claims. (Cl. 146-68) The present invention relates in general to a method of and apparatus for treating, materials; more particularly, it deals with the construction of a mill for comminuting materials to small particle size and with the use of the mill in processing materials of vegetable or animal origin.

In laboratory analysis or experimental treatment of various solids and semisolids it often proves necessary or desirable to comminute a sample of the material under consideration to small particle size for the purpose of making certain tests, or determining certain physical or chemical properties of the material or otherwise facilitating the analytical procedure. Such a need frequently arises, for example, in the agricultural research laboratory, the cereal chemistry research laboratory and, considering the industrial field, in laboratories serving the food canning industry, the grain milling industry and the meat packing or processing industry, to mention a few.

While my invention has many applications, it can be mentioned by way of illustration that determination of the moisture content of various grains and legumes, determination of the oil content of such vegetable materials as flax seed and soybeans, and determination of the fat content of such animal materials as hamburger meat, pork sausage and other dried and fresh meats are greatly facilitated by comminution; moreover, in connection with certain tests on vegetable and animal materials, it sometimes is desirable not only to reduce the material to fine particle size but also to thoroughly mix the particles with another substance of liquid or semiliquid character in order to form a homogeneously blended slurry.

An object of the invention, then, is to provide, for such uses as have been mentioned as well as others that will occur to those versed in the art, a laboratory mill capable of very quickly reducing to small. particle size a given sample of material and, when the occasion arises, forming homogenous blends or slurries of semiliquid consistency.

Another object is to provide a unit of the character indicated which is capable of performing the desired milling and/ or blending operation under conditions which prevent loss of any portion of the test material to the atmosphere, as is very important in making accurate quantitative analyses in the laboratory.

Still another object is to provide a device of the character indicated which, if necessary, is capable of performing the desired mixing or blending operations under controlled conditions of time and/or temperature.

A further object is to provide a laboratory mill which is extremely reliable in operation; which is sturdy and long lived; which is versatile as regards its ability to a process a wide variety of materials and its ability to meet a wide range ofconditions reflecting the varying laboratory needs'inexperimental work; which is simple and convenient to use; and which requires little or no maintenance. I

Yet another" object is to provide a laboratory mill capable of processing solid or semisolid materials of either fluent or non-fluent character and which by its action generates in the material being treated heat which is useful in carrying out certain experimental tests on the material; a feature of the invention resides in the provision of means for adding additional heat when such will facilitate the procedure, or removing heat from the test specimen during the milling operation when such is desirable or necessary to the test procedure.

A further object is to provide an apparatus for rapidly extracting moisture from' seeds, grains, legumes and other moisture-containing materials (or extracting other heatvolatile liquids from such materials) for the purpose of determining the moisture or liquid content thereof or for other purposes that will be self-evident to those versed in the art.

Still another object is to provide an improved method of and apparatus for making rapid determinations of the moisture content of grains or like substances.

Other and further objects of the invention, together with the features of novelty whereby the objects are achieved, will appear in the course of the following description.

In the drawings which form a part of the specification and are to be read in conjunction therewith, and wherein like reference numerals are used to indicate like parts of the various views:

Fig. l is a side elevational view of apparatus for extracting moisture from vegetable material or the like for the purpose of determining moisture content, which apparatus includes my improved milling unit; for purposes of illustration certain parts are broken away and others are shown in cross section;

Fig. 2 is a fragmentary cross-sectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is a sectional elevation of a portion of my milling unit illustrating a modified form thereof;

Fig. 4 is a sectional elevation of a portion of my milling unit illustrating another modified form thereof; and

Fig. 5 is an enlarged cross section of the milling blade taken along the line 5-5 of Fig. 4 in the direction of the arrows.

Referring more particularly to Fig. l, the numeral 10 indicates an upright post supported on a suitable base 12 having feet 14. At the upper end of the post there is a rigid mount 16 carrying an electric motor 18, the latter being positioned so that its shaft 20 is vertical. On the opposite side of the post from the motor the mount 16 has an integral arm 16a extending laterally and terminating in a headpiece 16b.

A vertical shaft 22 is journaled in the headpiece, being carried by suitable bearings 24. On the upper end of this shaft is a pulley 26 connected via belt 28 to a pulley 39 on the motor shaft 20whereby the motor is drivingly connected to shaft 22. It will be noted that mount 16 extends upwardly between opposite sides of the belt, and secured thereto by means of screws 32 or otherwise is a guard or shroud 34 which covers the belt and pulleys on the top, with its depending flange 34a extending downwardly around the margin of the belt.

The headpiece 16b is generally cylindrical and at its lower end is cut out as shown at 16c, forming opposed legs 16d. To these legs a horizontal disc-shaped cover plate 36 is secured in any suitable fashion as, for example, by means of bolts 38 (see Fig. 2). The cover plate is centrally apertured and shaft 22 has an extension 22a of reduced diameter extending downwardly through this aperture. A milling or cutter blade 40 is secured to the lower end of the shaft being thus spaced below the cover 36. On the underside of the cover is cemented or otherwise bonded a centrally apertured circular gasket 42, the purpose of which will be made clear presently. a

For use with my laboratory mill, I provide a generally cylindrical cup 44 for receiving a sample of the material to be comminuted. The upper rim of the cup is adapted to be clamped against the cover platein seating and sealing engagement with the gasket 42by the following means: Extending laterally from the post is an arm 46 having at its outer end an internally threaded hole in which is received the externally threaded member 48. The latter has a knob 50 at its lower end to permit turning it by hand, and at its upper end it has a circular rest or seat 52 to engage the bottom of the cup. Arm 46 is carried by a collar 46a encircling post 10 to turn thereon, and the collar is supported by means of a screw 54 received in a tapped hole in the post so that it extends radially outward therefrom as shown in Fig. 1. As will also be clear from this figure, the portion of the collar resting on the screw is a 90 segment cut out of the underside of the collar to form stop shoulders 46b and 46c limiting the swinging of arm 46 to a 90 arc about the post as an axis.

With the parts shown as positioned in Figs. 1, 3 and 4, cup 44 is clamped securely between the rest 52 and the underside of cover 36, its'rim being seated against the gasket 42 and the cup being concentric with shaft 22a. By turning knob 50 in a dire tion to relieve the clamping pressure, arm 46 can be swung to a position out of register with the bottom of the cup, whereupon the cup can be withdrawn downwardly from cover 36 to remove the cutter blade 40 therefrom. To replace the cup preparatory to another milling operation, it is advanced upwardly about the shaft until its rim engages the gasket; then arm 46 is swung back into the position shown, and knob 50 is turned in order to cause rest 52 to urge the cup upwardly, clamping it firmly in place.

For the purpose of controlling the temperature of the contents of the cup during a given milling operation, the cover plate 36 may be provided with a depending annular heating jacket or cooling jacket as shown in Figs. 1 and 3, or the jacketing may be omitted as shown in Fig. 4 where no such temperature control is required.

Referring first to Fig. 4, since this illustrates the simplest form of construction, it will be noted that the cover plate is provided'with a depending annular flange 36a which encircles the margin of the cup to hold same coaxial with the shaft 22a. milled into the cup after it is in place, the cover plate also is provided with a filling tube 56 having a removable cap 58. Shaft 22a is driven at high speedpreferably of the order of 14,000 to 16,000 R. P. M.-and in a typical milling operation after the shafthas come up to full speed. a measured quantity of the grain or other material to be milled is introduced into the cup gradually through the filling tube in order to avoid throwing a heavy load suddenly onto the motor.

As will be seen in Fig. 5, the cutter blade 40 has sharpened edge and its direction of travel (as indicated by the arrow) is such as to propel the material downwardly toward the cup bottom 44a; material below the blade travels back upwardly along the walls of the cup past the tips of the blade (see Fig. 4), so there is continuous circulation of the material within the cup. The cutting or comminuting action takes place, of course, principally in the region near the tips of the blade.

At the high rate of speed at which the blade tips travel it is found that 100 grams of whole soybeans, for example, will, with as little as six minutes of milling in my unit, be reduced to such fineness that 96% to 98% of the solid matter will pass through a standard No. 40 sieve. If in addition to reducing the particles to fine size it is desired to blend the particles with a solvent or liquid of any character, the latter can be introduced through the filling tube 56 while blade 40 continues to turn, and in a very brief interval a homogeneous mixture is obtained. Whether the material is milled in dry condition or wet For introducing material to be 4 condition, it will be clear that there can be no loss of any portion thereof, inasmuch as the cup 44 is closed and sealed by the gasketed cover 36.

In laboratory use, different materials will require different lengths of milling time, depending upon the character of the material being processed, the fineness to which it is desired to reduce the material, and various other factors. Thus a typical sample of wheat or other grain can be reduced to suitable fineness for determining its moisture content by conventional oven test methods with as little as one minutes preparatory milling in my apparatus, while other operations may require a ten-minute milling period or even more. In order that the milling time can be accurately controlled, yet flexible enough to meet all requirements, I provide my apparatus with an automatic time switch 57 (see Fig. 1) having a manually adjustable pointer-knob 54 by means of which the milling time can be preset; this switch is of known construction, and is so connected in the motor supply circuit (not shown) as to cut off the motor when the preset time has elapsed, thereby to terminate the milling operation.

Due to the impact of the cutter blade upon the material being treated and due also to the. agitation and frictional engagement of the blade with the material, a very considerable amount of heat is generated directly in said material. typical grain will raise it temperature'to 100 C. in approximately two minutes and to 200 C. in approximately five minutes. This heating is of advantage in some experimental procedures; in others-say, where the heat would cause undesirable volitalization of liquid fractions of the test specimen-the cup can be artificially cooled during the milling operation, and for this I prefer to use the arrangement illustrated in Fig. 3.

The construction shown in Fig. 3 is essentially like that of Fig. 4 except that the cover plate 36 is larger in diameter and has a depending annular cooling jacket 60 secured to its marginal portion by means of screws 62 or otherwise. The cooling jacket, comprises a hollow hous ing having a cylindrical inner wall 60a, a concentric outer wall 60b, a top wall 600, and a bottom wall 60d. For the sake of clarity in the drawing, inner wall 60a is shown spaced slightly from the exterior wall of cup 44, but it should be understood that in order to obtain a good heat exchange between the two, they should fit together as snugly as is possible without interfering with the removal of the cup when arm 46 is swung away from the bottom of the cup, as has been explained hereinbefore.

The jacket serves always to center cup 44 relative to shaft 22a during insertion and removal of the cup and of course maintains it coaxial with the shaft during milling. Accordingly, it is unnecessary that the underside of cover 36 have a central locating recess like that provided in the Fig. 4 embodiment for receiving the rim of the cup. However the central portion of cover 36 in Fig. 3 can be similarly recessed if desired, in which case the gasket 42 will be positioned in the recess.

The outer wall 6% of the jacket has nipples to which fluid inletand outlet lines 64 and 66 are connected; by this means water or any other suitable coolant 68 may be continuously circulated through the hollow interior of the jacket during the milling operation. Obviously, should it be desired to supply additional heat to the cup during milling, steam or other heated fluid can be supplied to the jacket in place of the coolant.

An alternative way of heating the cup during milling is shown in Fig. 1 and this construction is preferred where heating is desired. Here the cover plate 36 has a depending annular jacket 70 which is fundamentally like the jacket 60 already described except that it has no inlet or outlet for fluid and instead is provided with an electrical resistance heating coil 72 between the inner and outer walls. Electrical current for energizing the coil is supplied through the conductors 74. A temperature sensing element 76 extends into the upper portion of For instance, milling a gram sample of the cup through an aperture in the cover plate 36 and actuates a gauge 78 to indicate the temperature within the cup. Associated with the gauge is a thermostatic control 80 of conventional character for turning the current to'the resistance heater 72 on or off as may be needed in order to maintain the temperature within the cup at a selected value; the thermostatic control has an adjustment knob 82 for regulating the temperature at which the cup is to be maintained.

Also communicating with the interior of the cup when it is in place as shown in Fig. l is a vapor discharge tube 84 extending to a condenser of any suitable character, this having for convenience been illustrated in the drawing as a jacket 86 surrounding a portion of the tube with a cooling water inlet 88 and a water outlet 90 connected thereto; the condensed vapor may be collected in a conventional volumetric measuring device, for example, the graduate 92.

It will be understood that if it is not desired to condense and collect vapor discharge from the cup 44 during the milling operation, tube 84 and the associated condenser can be omitted, in which case the vapor will discharge to atmosphere through the opening left in cover 36 by the removal of tube 84; or, if desired, this opening can be plugged to keep the vapor within the sample cup 44. The arrangement, as illustrated, however, is particularly useful in making determinations of the moisture content of grain or like substances, the procedure being as follows:

A known quantity of grain is placed in the sample cup along with a quantity of a liquid which is immiscible with water but which has a boiling point slightly above, but not too far removed from, that of water; for the latter I find it convenient to use orthodichlorobenzene or a blend of other naptha solvents having a boiling point of the order of 140 C. The quantity of liquid used is not critical but I prefer to use an amount approximately equal to the amount of grain. The cup is installed in my apparatus shown in Fig. l and the mill is placed in operation to comminute the grain and generate heat therein as has been previously described. Approximately five minutes operation without use of the heating jacket and a considerably shorter period of time using the heating jacket (the precise length depending upon the temperature maintained by means of the thermostatic control) will serve to vaporize all of the moisture originally contained in the grain and also vaporize the added immiscible liquid as well. The vapors leave the cup or test cell through the tube 34 and pass into the condenser, the condensate being collected in the graduate Due to the difference in specific gravity and immiscible character of the liquids, they will settle at different levels in the graduate, making it possible to easily determine the exact volume of water collected, and on the basis of this, it is possible to compute the moisture content of the original grain sample.

My purpose in using the. orthodichlorbbenzene or equivalent immiscible liquid is to wash from the condenser any water condensate that otherwise might remain therein in the form of dew collected on the inner wall of tube 84, thereby to remove the possibility that the water collected in graduate 92 does not reflect the full amount of moisture contained in the grain. Thus, it will be evident that to accomplish the desired washing action the boiling point of theimmiscible liquid should be at least as high and preferably a little higher than that of water in order that it will vaporize after all of the moisture in the grain has reached the condenser. If other means for washing residual water condensate from the condenser are used, it is of course unnecessary to add the immiscible liquid to the sample cup in the first instance, and the grain sample can instead be milled dry. By the same token, the moisture content determination may be made with dry milling if the residual moisture remaining in the condenser is too little to affect the ac- U curacy of the final measurement of the water collected in the graduate 92, or if mathematical compensation is made for failure of any moisture vapor to reach the graduate.

While I have described the operation only as applied to determination of the moisture content of grain, it should be evident that if the material to be comminuted in my mill contains a volatile liquid other than water, the amount thereof likewise can be determined by the procedure described.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinbefore set forth, together with other advantages which are obvious and which are inherent thereto.

it will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the appended claims.

Inasmuch as many possible embodiments of the invention may be made without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. In a laboratory mill, an openbottom housing having an apertured top, a suitable support for said housing positioned above the top thereof, a cup received in said housing, clamping means applying an upward thrust on said cup thereby to urge the rim thereof into seating engagement with the underside of said top, a vertical power-driven shaft journaled in said support and extending downwardly through the aperture in said top with its lower portion received in said cup, a milling blade on said lower portion of the shaft, said blade comprising a unitary member having a plurality of arms extending radially from said shaft, each arm being in a plane generally parallel to the bottom of the cup and in close proximity thereto, the leading edge of each arm being beveled to form an acute angle with the upper surface of the arm and an obtuse angle with the lower sur face of the arm, the side wall of said housing comprising an annular skirt depending from said top and closely embracing the sides of the cup and centering same relative to said shaft, means in the side wall of the housing for heating said cup, and said clamping means being releasable to permit removal of the cup through the bottom opening of the housing.

2 A device as in claim 1 wherein said heating means comprises an electrical resistance having a source of electrical current connected thereto.

3. in a laboratory mill, an open bottom housing having an apertured top, a suitable support for said housing positioned above the top thereof, a cup received in said housing, clamping means applying an upward thrust on said cup thereby to urge the rim thereof into seating engagement with the underside of said top, a vertical power driven shaft journaled in said support and extending downwardly through the aperture in said top with its lower portion received in said cup, a milling blade on said lower portion of the shaft, said blade comprising a unitary member having a plurality of arms extending radially from said shaft, each arm being in a plane gen- I erally parallel to the bottom of the cup and in close proximity thereto, the leading edge of each arm being beveled to form an acute angle with the upper surface of the arm and an obtuse angle with the lower surface 7 4. In a laboratory mill, an open-bottom housing having an apertured top, a suitable support for said housing positioned above the top thereof, a cup received in said housing, clamping means applying an upward thrust on said cup thereby to urge the rim thereof into seating engagement with the underside of said top, a vertical power-driven shaft journaled in said support and extending downwardly through the aperture in said top with its lower portion received in said cup, a milling blade on said lower portion of the shaft, said blade comprising a unitary member having a plurality of arms extending radially from said shaft, each arm being in a plane generally parallel to the bottom of the cup and inclose proximity thereto, the leading edge of each arm being beveled to form an acute angle with the upper surface of the arm and an obtuse angle with the lower surface of the arm, the side wall of said housing comprising an annular skirt depending from said top and closely embracing the sides of the cup and centering same relative to said shaft, said skirt containing a hollow cavity encircling said cup, fluid inlet and outlet ports in the skirt communicating with said cavity, and said clamping means being releasable to permit removal of the cup through the bottom opening of said housing.

5. in a laboratory mill, a cup, an upright post, an upper arm and a lower arm extending laterally from said post, one of said arms being swingably mounted on said post to travel in a generally horizontal are between a first position and a second position, the outer ends of said arms being in vertical alignment in one of said positions, means for releasably clamping said cup between the outer ends of said arms when they are in vertical alignment, said means including, on the upper arm, a centrally apertured cover against which the rim of said cup seats, a power-driven shaft journaled in the upper arm and extending downwardly through the aperture in said cover, a single milling blade on the lower portion of the shaft received in said cup, said blade comprising a unitary member having a plurality of arms extending radially from said shaft, each arm being in a plane generally parallel to the bottom of the cup and in close proximity thereto, and the leading edge of each arm being beveled to form an acute' angle with the upper surface of the arm and an obtuse angle with the lower surface of the arm, and an annular housing concentric with said shaft and depending from said cover, said housing forming with said cover a downwardly opening cavity for receiving said cup and centering same relative to said shaft, said housing comprising a double-wall vessel containing a fluid, and said vessel having a fluid inlet and a fluid outlet to facilitate the circulation of fluid therethrough.

6. In a laboratory mill, a cup, an upright post, an upper arm and a lower arm extending laterally from said post, one of said arms being swingably mounted on said post to travel in a generally horizontal are between a first position and a second position, the outer ends of said arms being in vertical alignment in one of said positions, means for releasably clamping said cup between the outer ends of said arms when they are in vertical alignment, said means including, on the upper arm, a centrally apertured cover against. which the rim of said cup seats, a power-driven shaft journaled in the upper arm and extending downwardly through the aperture in said cover, a single milling blade on the lower portion of the shaft received in said cup, said blade comprising a unitary member having a plurality of arms extending radially from said shaft, each arm being in a plane generally parallel to the bottom of the cup and in close proximity thereto, and the leading edge of each arm being beveled to form an acute angle with the upper surface of the arm and an obtuse angle with the lower surface of the arm, and an annular housing concentric with said shaft and depending from said cover, said housing forming with said cover a downwardly opening cavity for receiving said cup and centering same relative to said shaft, and means in said housing for cooling said cup when same is in the cavity.

7. In a laboratory mill, a cup, an upright post, an upper arm and a lower arm extending laterally from said post, one of said arms being swingably mounted on said post to travel in a generally horizontal are between a first position and a second position, the outer ends of said arms being in vertical alignment in one of said positions, means for releasably clamping said cup between the outer ends of said arms when they are in vertical alignment, said means including, on the upper arm, a centrally ured cover against which the rim of said cup seats, a power-driven shaft journaled in the upper arm and extending downwardly through the aperture in said cover, a single milling blade on the lower portion of the shaft received in said cup, said blade comprising a unitary member having a plurality of arms extending radially from said shaft, each arm being in a plane generally parallel to the bottom of the cup and in close proximity thereto, and the leading edge of each arm being beveled to form an acute angle with the upper surface of the arm and an obtuse angle with the lower surface of the arm, and an annular housing concentric with said shaft and depending from said cover, said housing forming with said cover a downwardly opening cavity for receiving the cup and centering same relative to said shaft, and means in said housing for heating said cup when same is in the cavity.

8. A device as in claim 7 wherein said heating means comprises an electrical resistance having a source of electrical current connected thereto.

9. In a laboratory mill, a cup, an upright post, an upper arm and a lower arm extending laterally from said post, one of said arms being swingably mounted on said post to travel in a generally horizontal are between a first position and a second position, the outer ends of said arms being in vertical alignment in one of said positions, means for releasably clamping said cup between the outer ends of said arms when they are in vertical alignment, said means including, on the upper arm, a centrally apertured cover against which the rim of said cup seats, a power-driven shaft journaled in the upper arm and extending downwardly through the aperture in said cover, a single milling blade on the lower portion of the shaft received in said cup, said blade comprising a unitary member having a plurality of arms extending radially from said shaft, each arm being in a plane generally parallel to the bottom of the cup and in close proximity thereto, and the leading edge of each arm being beveled to form an acute angle with the upper surface of the arm and an obtuse angle with the lower surface of the arm, and an annular housing concentric with said shaft and depending from said cover, said housing forming with said cover a downwardly opening cavity for receiving said cup and centering same relative to said shaft.

References Cited in the file of this patent UNITED STATES PATENTS 165,442 Goddard July 13, 1875 419,200 Kahlenberg Jan. 14, 1890 848,616 Brown et al. Mar. 26, 1907 982,765 Crisfield Jan. 24, 1911 1,290,734 Goodhue Jan. 7, 1919 1,392,116 Chopin Sept. 27, 1921 2,078,190 Bemis Apr. 20, 1937 2,361,844 Horner Oct. 31, 1944 2,564,160 Jones Aug. 14, 1951 2,665,724 Lundell Jan. 12, 1954 2,710,743 Betry June 14, 1955 2,734,728 Myers Feb. 14, 1956

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