US3734468A - Mixing devices - Google Patents

Mixing devices Download PDF

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Publication number
US3734468A
US3734468A US00112010A US3734468DA US3734468A US 3734468 A US3734468 A US 3734468A US 00112010 A US00112010 A US 00112010A US 3734468D A US3734468D A US 3734468DA US 3734468 A US3734468 A US 3734468A
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US
United States
Prior art keywords
rotor
rotors
arm
arms
lobes
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00112010A
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English (en)
Inventor
Hsun Cheng D Chung
J Davis
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National Research Development Corp UK
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National Research Development Corp UK
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    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01J—MANUFACTURE OF DAIRY PRODUCTS
    • A01J17/00—Kneading machines for butter, or the like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/60—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a horizontal or inclined axis
    • B01F27/70—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a horizontal or inclined axis with paddles, blades or arms
    • B01F27/701—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a horizontal or inclined axis with paddles, blades or arms comprising two or more shafts, e.g. in consecutive mixing chambers
    • B01F27/702—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a horizontal or inclined axis with paddles, blades or arms comprising two or more shafts, e.g. in consecutive mixing chambers with intermeshing paddles

Definitions

  • Each rotor has like symmetrical section along its length defined by a pair of radial arms.
  • Each arm has concave sides, with adjacent ones of these sides merging into convex axial portions, and radially outer peripheries which pass closely adjacent the lobes surfaces.
  • This geometry defines leading and trailing peripheral tips whereby each leading tip wipes its lobe and a trailing tip side of the other rotor, each trailing tip wipes the leading tip side of the other rotor, and each arm periphery rolls around an axial portion of the other rotor.
  • Material to be mixed is charged and discharged axially for batch or continuous operation, and the rotors can provide a screw action for the latter operation. Similar arrangements involving more lobes in the chamber, and/or more arms for each rotor, can be evolved.
  • This invention relates to mixing devices and more particularly, but not exclusively, such devices for homogenizing and blending paste-like materials, such as butter.
  • An object of the present invention is to provide an improved mixing device which may better satisfy the above requirements or which can be used with advantage for other mixing operations.
  • a mixing device comprising: a hollow housing defining a cylindrical chamber having symmetrical cross section formed by a plurality of like lobes with circular arcuate peripheries, the circular central axes of adjacent lobes being mutually displaced by a distance less than the sum of the radii thereof, and said housing having port means in at least one end thereof for passage of material to and from said chamber; a plurality of similar rotors individually mounted in respective ones of said lobes for rotation about said central axes, each rotor having like cross-sectional form along its axis defined by a plurality of like radially extending arms, each of said arms being defined, in turn, by generally concave radially extending sides and a radially outer periphery which passes closely adjacent the respective lobe periphery during rotation, and said concave sides of adjacent ones
  • sectional geometry of the rotors will be such that the sides of each arm meet their common periphery in generally acute tips to provide wiping or scavenging edges along the lengths of the rotors. These edges can be distinguished as between leading and trailing edges relative to the direction of rotation, and the leading edges serve to wipe the chamber lobes and collect material to be mixed.
  • the sectional geometry is further such that this collected material is subjected to a compacting action. This action involves wiping of the arm side on which material has been collected by the trailing edge of an arm of an adjacent rotor, while the periphery of the latter arm effectively rolls and slides over the convex axial portion with which the former arm merges. This will be better understood from the further description hereinafter, but it remains to note here that the compaction squeezes the collected material through small inter-rotor or rotor/chamber clearances giving a very efficient mixing action.
  • the rotors can be cylindrical, or successive portions of each rotor along its axis can be angularly displaced, about such axis in a progressive manner, or the rotors can be smoothly twisted about their axes, such as in helical manner.
  • the mixer can be used for batch operation or continuous operation. In this last case there will be port means at both ends of the housing and the use of screwlike forms of rotor may be preferred to induce flow of material to be mixed through the mixing chamber.
  • the rotors may be of hollowed form for the passage of heated or coolant fluid therethrough in order to afford heat exchange between the relevant fluid and material being mixed.
  • FIG. 1 diagrammatically illustrates in side view one embodiment of a mixer according to the invention
  • FIG. 2 shows an idealized sectional form for the rotors of the mixer of FIG. 1,
  • FIGS. 3a to 3e illustrate successive relative dispositions for a pair of rotors of the form of FIG. 2,
  • FIG. 4 illustrates a part view from one end of the embodiment of FIG. 1 and shows rotors of modified sectional form relative to that of FIG. 2, and
  • FIGS. 5, 6 and 7 diagrammatically illustrate rotors subject to yet further modification.
  • the housing 10 defines a cylindrical chamber 1 1 formed by two identical part circular cylindrical lobes Ila and 11b which provide symmetrical 8-shaped cross-sectional form.
  • the housing is made up of a body part 10a which serves to define the curved surfaces of the lobes, and end plates 10b and which are bolted or otherwise suitably connected to the body part 10a in sealing relation.
  • the mixer is provided with two identical rotors 12a and 12b respectively mounted for rotation about the central axes of the lobes 11a and 11b.
  • Each of these rotors has two diametrally opposed arms having general geometrical form as described above and discussed in more detail hereinafter.
  • the rotors have stub shaft projections 13 at their ends, which shafts are mounted for rotation in the end plates of the housing and pass in effective sealing relation through at least one of these plates.
  • the rotor shafts are coupled for rotation in predetermined phase relation.
  • This coupling is denoted by intermeshed gear wheels 14 and 15 respectively fixed on the upper shafts of rotors 12a and 12b, although any other suitable drive coupling can be employed.
  • one of the shafts is further coupled with a drive motor 16 whereby the rotors are driven in mutually opposite senses by way of their shafts and gear coupling.
  • the end plates of the housing are provided with ports with which conduits 8 communicate for passage of material to and from the mixing chamber.
  • the provision of ports and conduits in association with both end plates assumes passage of material through the chamber for continuous operation of the mixer. Clearly, it may be sufficient to port only one of the end plates for the purposes of charging and discharging in batch operation.
  • the relevant form of rotor has a pair of diametrally opposed, radially projecting arms merge to form a convex shaping 23 around the axial portion of the rotor..
  • the peripheries 22 are defined as circular arcs of radius R, equal to the lobe radius, and subtended angles of 90 at the center of the section, namely the rotor axis of rotation,
  • the convex shapings are defined by circular arcs of radius R where R e R, and e I, and these arcs also each subtend angles of 90 at the section center,
  • FIGS. 3a to 32 show successive positions of the rotors having sectional geometry as in FIG. 2, and in a mixer as described with reference to FIG. 1.
  • the rotors are designated as 12a and 12b, and are arranged for rotation in mutually opposite senses with their axes parallel and spaced by a distance (R, R the rotors being housed in a vessel with an inner surface defined by the peripheral paths of rotation 9 of the rotors.
  • FIG. 2 Now embodiment of the geometry of FIG. 2 in the mixer of FIG. 1 would lead to wear over the whole of the rotor arm surfaces, with more severe wear at the tips due to their longer period of engagement with other surfaces during a cycle of rotation. Accordingly, during practical development of the invention, a first prototype model was made generally as illustrated by FIGS. 1 and 2, but with the rotor arm radius reduced slightly, as indicated in broken line in FIG. 2, to give a small clearance between the two rotors and also between the rotors and vessel. It was also considered that such a clearance would allow shearing of the material being mixed to take place between the rotors and the vessel.
  • the result of the sweeping action of the tips is impaired by the provision of a clearance.
  • the desired shearing action is small in the case of .pastes since they act more like a plastic than a viscous material, thus tending to stick to the vessel without suffering appreciable deformation.
  • the prototype form was modified as shown in FIG. 4 by filling out the initial clearance with strips as denoted at 17 at the leading tips of the rotor arms.
  • This modification gives rise to the ini-' tially contemplated advantageous sweeping action, while reducing the areas of wear and facilitating reestablishment of the regions of greater wear, namely, the arm tips.
  • the tips 17 can be made of metal, or plastics material, or a combination of both. These strips can be permanently secured to the rotors, this being probably best suited to use of metal tips, when welding and like techniques or even integral fabrication with the rotor will be appropriate. Alternatively, the tips can be releasably secured as by bolts or equivalent means, this being probably best suited to use of plastics material strips in association with metal backings.
  • FIG. 4 also further particularizes the disposition of the ports in the end plates of the mixer housing.
  • the inlet port is indicated in broken line at 18 and is of slot form with its axis parallel to and laterally displaced from the common diameter of the two lobes to bridge the lobe spaces.
  • twin outlet ports as indicated at 19 in a region of high pressure during operation of the mixer. This region lies between the rotor axes but off-set from the common diameter towards the direction from which the rotor leading edges approach.
  • FIG. 5 A further consideration in rotor geometry is that of its form in the axial direction. .It has been indicated above that this can be cylindrical and such a rotor is indicated in FIG. 5.
  • the rotor of FIG. 5 is further particularized by being hollow, with the rotor hollow communicating with hollow stub shafts at its ends. These shafts will, in turn, communicate with conduits for passage of heated or coolant fluid through the rotor so that the rotor affords a heat exchange function.
  • FIG. 6 shows another form of rotor modified from that of FIG. 5 in that successive portions along the axial direction are relatively angularly displaced about the axis in a progressive manner.
  • FIG. 7 shows a yet further rotor modification in which the rotor is smoothly twisted to spiral or screw form along its axis. This twisting can be of a uniform nature to provide a helical screw form.
  • FIGS. 6 and 7 are useful for continuous through-flow mixing operations by assisting .axial displacement of mixed material.
  • this through motion is detrimental to an ideal mixing action and the choice of relative angular displacement or spiral pitch should be chosen to compromise between these requirements.
  • a helical spiral pitch of one turn in 211' R tan 60 axial length is useful in the present context.
  • the power requirement of this pilot operation was 0.3 hp. at the end of mixing, and the weight of the mixed butter was 5 lbs.
  • the power requirement is about 40 50 hp. when dealing with a batch of X 56 840 lbs. If one scales up the pilot operation on the basis of equal power requirement per pound of butter, the present mixer would require about 50 hp. at the start falling to about 25 h.p. at the end of mixing. Such a result would show no significant saving in power, but would afford a significantly shorter mixing time compared to the conventional operation.
  • a mixing device comprising: a hollow housing defining a cylindrical chamber having symmetrical cross section formed by a plurality of like lobes with circular arcuate peripheries, the circular central axes of adjacent lobes being mutually displaced by a distance less than the sum of the radii thereof, and said housing having port means in at least one end thereof for passage of material to and from said chamber; a plurality of similar rotors individually mounted in respective ones of said lobes for rotation about said central axes, each rotor having like transverse radial cross-sectional form at substantially all points along its axis defined by a plurality of like radially extending arms, each of said arms being defined, in turn, by generally concave radially extending sides and a generally convex radially outer periphery which passes closely adjacent the respective lobe periphery during rotation, and said concave sides of adjacent ones of said arms in each rotor merging in a convex axial portion; and means coupling said
  • each leading tip wipes the periphery of its lobe and the trailing tip side of an adjacent rotor arm; and each trailing tip of one arm wipes the leading tip side of an adjacent rotor arm while the periphery of said one arm effectively rolls on and slides over the convex axial portion with which said leading tip side merges.
  • a device wherein the ratio between the radii of curvatures of said arm peripheries and convex portions is 1 0.3.
  • each rotor comprises a pair of arms, the 2 of said arms and said convex portions each subtend an angle of substantially at the rotor axis, and each arm side at least approximates in sectional form to a curve defined by the equations:
  • R is the rotor arm radius and e is the ratio of the convex axial portion radius to R 5.
  • a device wherein successive axial portions of each of said rotors are cylindrical and mutually angularly displaced about the rotor axis in progressive manner.
  • each of said rotors has its arms twisted around and along its axis to spiral form.
  • a device wherein the pitch of said helix is at least approximately one turn in 21rR /tan 60 of axial length, where R is the maximum radius of the rotor.

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  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Animal Husbandry (AREA)
  • Environmental Sciences (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
US00112010A 1970-02-03 1971-02-02 Mixing devices Expired - Lifetime US3734468A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB522570 1970-02-03

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JP (1) JPS5422612B1 (de)
DE (1) DE2105020A1 (de)
GB (1) GB1335063A (de)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4025056A (en) * 1974-07-15 1977-05-24 Imperial Chemical Industries Limited Mixing apparatus
US4025058A (en) * 1975-08-14 1977-05-24 Dai Nippon Toryo Co., Ltd. Continuous extruder for thermosetting resins
US4188131A (en) * 1977-07-08 1980-02-12 Agence Nationale De Valorisation De La Recherche (Anvar) Self-scraping mixers
US4556324A (en) * 1984-05-01 1985-12-03 E. I. Du Pont De Nemours And Company Apparatus for forming films of constant thickness
WO1990004919A1 (en) * 1988-11-09 1990-05-17 Scherping Systems, Inc. Food processing vat
FR2645713A1 (fr) * 1989-04-18 1990-10-19 Ault Foods Pate a tartiner a teneur reduite en graisse, son procede de production et intermediaire a cet effet
US5044760A (en) * 1989-09-08 1991-09-03 Kabushiki Kaisha Kobe Seiko Sho Closed type kneader
US5399012A (en) * 1991-08-09 1995-03-21 Bayer Aktiengesellschaft Fully self-cleaning reactor/mixer with a large usable volume
US5505536A (en) * 1993-08-10 1996-04-09 Bayer Aktiengesellschaft Multiple shaft mixing device providing full kinematic self-cleaning
EP1101525A1 (de) * 1999-11-10 2001-05-23 Buss- SMS GmbH Verfahrenstechnik Mischer und Reaktor
US20050024986A1 (en) * 2003-07-30 2005-02-03 Mattingly Joseph E. Kneading element and related articles
WO2006111816A1 (en) * 2005-04-18 2006-10-26 Collette Nv Continuous granulator and a method of continuous granulation of powder material
US20120125738A1 (en) * 2009-08-18 2012-05-24 Toyota Jidosha Kabushiki Kaisha Screw segment
US20150165398A1 (en) * 2012-07-30 2015-06-18 Shin Nichinan Co., Ltd. Kneading apparatus
US9073019B2 (en) 2010-04-19 2015-07-07 Cheese & Whey Systems, Inc. Blade arrangement for a food processing vat

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8804313D0 (en) * 1988-02-24 1988-03-23 Apv Plc Improvements in/relating to mixers

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB173457A (en) * 1921-04-11 1922-01-05 Richard Mueller Reducing and mixing machine
US2581451A (en) * 1949-09-14 1952-01-08 Laval Steam Turbine Co Mixing pump

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB173457A (en) * 1921-04-11 1922-01-05 Richard Mueller Reducing and mixing machine
US2581451A (en) * 1949-09-14 1952-01-08 Laval Steam Turbine Co Mixing pump

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4025056A (en) * 1974-07-15 1977-05-24 Imperial Chemical Industries Limited Mixing apparatus
US4025058A (en) * 1975-08-14 1977-05-24 Dai Nippon Toryo Co., Ltd. Continuous extruder for thermosetting resins
US4188131A (en) * 1977-07-08 1980-02-12 Agence Nationale De Valorisation De La Recherche (Anvar) Self-scraping mixers
US4556324A (en) * 1984-05-01 1985-12-03 E. I. Du Pont De Nemours And Company Apparatus for forming films of constant thickness
WO1990004919A1 (en) * 1988-11-09 1990-05-17 Scherping Systems, Inc. Food processing vat
FR2645713A1 (fr) * 1989-04-18 1990-10-19 Ault Foods Pate a tartiner a teneur reduite en graisse, son procede de production et intermediaire a cet effet
EP0394013A2 (de) * 1989-04-18 1990-10-24 Ault Foods Limited Verfahren zur Herstellung eines Brotaufstrichs mit niedrigem Fettgehalt und Zwischenprodukt
EP0394013A3 (de) * 1989-04-18 1991-12-04 Ault Foods Limited Verfahren zur Herstellung eines Brotaufstrichs mit niedrigem Fettgehalt und Zwischenprodukt
US5044760A (en) * 1989-09-08 1991-09-03 Kabushiki Kaisha Kobe Seiko Sho Closed type kneader
US5399012A (en) * 1991-08-09 1995-03-21 Bayer Aktiengesellschaft Fully self-cleaning reactor/mixer with a large usable volume
US5505536A (en) * 1993-08-10 1996-04-09 Bayer Aktiengesellschaft Multiple shaft mixing device providing full kinematic self-cleaning
EP1101525A1 (de) * 1999-11-10 2001-05-23 Buss- SMS GmbH Verfahrenstechnik Mischer und Reaktor
US20050024986A1 (en) * 2003-07-30 2005-02-03 Mattingly Joseph E. Kneading element and related articles
US7188992B2 (en) * 2003-07-30 2007-03-13 Americhem, Inc. Kneading element and related articles
US20070147169A1 (en) * 2003-07-30 2007-06-28 Mattingly Joseph E Jr Kneading element and related articles
WO2006111816A1 (en) * 2005-04-18 2006-10-26 Collette Nv Continuous granulator and a method of continuous granulation of powder material
US20080159067A1 (en) * 2005-04-18 2008-07-03 Collette Nv Continuous Granulator and Method of Continuous Granulation of Powder Material
US8708551B2 (en) * 2005-04-18 2014-04-29 Collette Nv Continuous granulator and method of continuous granulation of powder material
US20120125738A1 (en) * 2009-08-18 2012-05-24 Toyota Jidosha Kabushiki Kaisha Screw segment
US9085093B2 (en) * 2009-08-18 2015-07-21 Toyota Jidosha Kabushiki Kaisha Screw segment
US9073019B2 (en) 2010-04-19 2015-07-07 Cheese & Whey Systems, Inc. Blade arrangement for a food processing vat
US10278541B2 (en) 2010-04-19 2019-05-07 Custom Fabricating & Repair, Inc. Blade arrangement for a food processing vat
US20150165398A1 (en) * 2012-07-30 2015-06-18 Shin Nichinan Co., Ltd. Kneading apparatus
US9707527B2 (en) * 2012-07-30 2017-07-18 Shin Nichinan Co., Ltd. Kneading apparatus with rotary shafts having kneading members

Also Published As

Publication number Publication date
JPS5422612B1 (de) 1979-08-08
GB1335063A (en) 1973-10-24
DE2105020A1 (de) 1971-09-16

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