[go: up one dir, main page]

US3817461A - Agitator mill - Google Patents

Agitator mill Download PDF

Info

Publication number
US3817461A
US3817461A US00296526A US29652672A US3817461A US 3817461 A US3817461 A US 3817461A US 00296526 A US00296526 A US 00296526A US 29652672 A US29652672 A US 29652672A US 3817461 A US3817461 A US 3817461A
Authority
US
United States
Prior art keywords
mill
outlet chamber
shaft
sealing
container
Prior art date
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
Application number
US00296526A
Other languages
English (en)
Inventor
R Forster
A Geissel
R Lehnert
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Erich Netzsch GmbH and Co Holding KG
Original Assignee
Erich Netzsch GmbH and Co Holding KG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Erich Netzsch GmbH and Co Holding KG filed Critical Erich Netzsch GmbH and Co Holding KG
Application granted granted Critical
Publication of US3817461A publication Critical patent/US3817461A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
    • B02C17/16—Mills in which a fixed container houses stirring means tumbling the charge

Definitions

  • the invention relates to an agitator mill comprising a container for a material to be ground and particles for grinding it, an adjacent outlet chamber separated from the container by a separator which only passes the ground material, agitating means for'stirring the contents of the container, mounted on a shaft passing through the separator and out through an opening in an opposed wall of the outlet chamber.
  • the invention is concerned with the sealing of the agitator shaft in relation to the outlet chamber and the grinding particle separator.
  • Flowable material to be ground may, for example, be powdered substances, granulates, agglomerates, 'plastics substances and/or liquids in which relatively large particles may be contained. lnparticular, the material to be ground may be a paste prepared from solid particles contained in a liquid medium. Flowable material has to be processed inter alia in the foodstuffs industry, chemicals industry and in the dyestuffs and paints industry, for which purpose agitator millsof the type described are particularly suitable and are to an ever increasing extent replacing roller stands.
  • agitating means in-the grinding container stir a mixture of material to be ground and a charge of solid grinding particles, which term is used hereinto include spherical or' approximately spherical bodies made from steel, glass, porcelain or similar materials generally with dimensions of 0.5 to 3 or 5 mm.
  • the material to be ground is in most cases passed into thegrinding container from below by an infinitely variable feed pump and, after passing through the grinding zone, it is drawn off at the upper end of the grinding container through a grinding particle separating device which retains the grinding particles in the container and only allows passage of the ground material into an outlet chamber, on the top of the grinding container.
  • the adequately ground or dispersed material flows through a lateral outlet from the outlet chamber into a receiving vessel or the like.
  • the separating device takes the form of a plane or slightly conical sieve, a perforated wall or a so-called friction gap, which is an annular gap between coaxial parts of the grinding container and the agitator shaft.
  • agitator mills are also used for comparatively highly. viscous media, e.g. printing ink, offset inks, letterpress inks, filling compositions, color concentrates and the like.
  • viscous media e.g. printing ink, offset inks, letterpress inks, filling compositions, color concentrates and the like.
  • the agitator shaft which, in the case of agitator mills with vertical cylindrical and mostly very slim grinding containers, is usually introduced upwardly into the latter, must be sealed with respect to an upper closure of the container, e.g. with respect to the cover of an outlet chamber.
  • the outlet chamber is regarded as the space provided above the separating device which constitutes the upper closure of the grinding container.
  • the outlet chamber must be separated from the grinding zone (in the grinding container) to prevent the ingress of grinding particles and at its upper end it must be so sealed in relation to the agitator shaft, that no processed material can emerge.
  • a problem in the case of the hitherto known agitator mills which are closed in this way is the sealing of the agitator shaft which extends up through the outlet chamber from the grinding container.
  • This shaft which is generally freely mounted only above the grinding container cannot be maintained free from vibrations, particularly as it has to rotate in a mixture of grinding particles and material being ground, such a mixture not being completely homogeneous.
  • the occurrence of resonance phenomena or the like leads to radial oscillatory movements of the agitator shaft.
  • These oscillations can give rise to difficulties in the sealing of the agitator shaft by means of a compression gland. Difficulties, however, also arise due to solvents attacking the materials of the gland packing or other elastic seal, for example, lipped seal.
  • An object of the invention is to improve the sealing of the agitator shaft at the point where it passes through the cover of the outlet chamber, and preferably also where it passes through the separating device, in such a way that problems of wear are alleviated, the seal being easily constructed with a few parts in order to facilitate servicing and cleaning of the outlet chamber.
  • an. agitator mil comprises a container for the material to be ground and particles for grinding it, an adjacent outlet chamber separated from the container by a separator which only passes the ground material, agitating means for stirring the contents of the container, mounted on a shaft passing through the separator and out through an opening in an opposed wall of the outlet chamber, and, for sealing the said opening, a hydrodynamic seal comprising a rotary body mounted coaxially with the shaft to rotate with it and having a sealing surface separated from the inner surface of the said wall of the discharge chamber by a small clearance.
  • the invention is based on the fact that a material which it is difficult to seal, such as a flowable very finely comminuted material which is present at the sealing locations, and which isat least at dynamic pressure, can be sealed off with a hydrodynamic seal, in other words a seal which dispenses with parts which are in frictional contact with one another. Since the sealing body, like all the other parts of the mill, may, in the region of ground material emergence, be constructed from metal, the problem of solvent attack which is present with other soft-elastic seals, does not arise.
  • the sealing body is therefore in the form of a disc having a plane sealing surface facing a plane surface of the wall of the outlet chamber. This represents a considerable simplification of the construction.
  • the shaft is mounted substantially vertically and passes out through the top wall of the outlet chamber which is situated above the container, the container being of circular section coaxial with the shaft.
  • the sealing disc preferably extends to a point close to its peripheral wall. This has the effect of increasing the length of the narrow gap in the direction of possible leakage. This length may also be increased by providing a labyrinth seal in the opening in the wall of the outlet chamber where the shaft passes through it, for example, by providing a sealing disc with a hub projecting through the opening and having a flange overlying the outer face of the wall.
  • the sealing action may be increased by providing the surface of the sealing plate facing the wall of the outlet chamber with a spiral groove or a spiral web which carries the material to be ground outwards, or with annular ribs coaxial with the shaft and projecting into grooves in the wall of the outlet chamber or vice versa.
  • the possibility of employing various features of the sealing device depends on how large the clearance must be, and this in turn depends on bending oscillations of the agitator shaft which may occur. If the agitator shaft is freely mounted only above the grinding container, in a stand in the agitator mill, so that considerable bending oscillations may occur, then the clearance must be suitably large to ensure that even if slightly tilted the sealing disc will not come into contact with the cover or the wall of the outlet chamber. Conveniently the sealing disc and the cover of the outlet chamber may be divided so that they can be removed from the shaft to give access to the outlet chamber. Moreover, preferably the sealing disc is adjustably mounted on the agitator shaft so that the clearance can be adjusted.
  • a top wall of the outlet chamber has on it a cup surrounding the agitator shaft to receive a sealing fluid.
  • the cup may be closed by a cover sealed in relation to the shaft so as to be capable of holding the sealing fluid under pressure.
  • the cup may be filled with a liquid or with an inert gas in order to avoid evaporation of solvent in the ground material.
  • the sealing body may carry pump vanes arranged to relieve the pressure on the sealing clearance by directing medium away from it.
  • Such vanes may be adjustable and/or replaceably secured to the sealing body so that their pumping action can be adapted to particular circumstances such as the output or drive load, rate of delivery and the viscosity of the ground material.
  • the pump vanes are inclined obliquely to their direction of movement and to avoid excessive stressing of the ground material the vanes may have apertures in them.
  • the shaft and separator may be provided with a separating structure comprising a sleeve mounted on the shaft with radial clearance relatively to the opening in the separator, and flanges projecting radially beyond the margin of the said opening and spaced from it by a distance smaller than the radius of the smallest grinding particles employed.
  • the upper and lower flanges of the separator unit are axially adjustable relatively to the shaft.
  • Such an arrangement relies upon the axial clearances to prevent the passage of the grinding particles and hence the radial clearance may be somewhat greater to allow for bending oscillations and radial deflections of the agitator shaft.
  • the lower face of the lower separating ring may taper conically downwards so as to give improved deflection of the grinding particles, particularly if the separating device is in the form of a slightly conical sieve having an inclined angle of between l40 and 160, preferably about 150.
  • Such a slightly conical separating sieve having its outer edge situated higher than its middle has the advantage that upon completion of the grinding process drying out can be prevented. Non-drying suspensions of ground material can remain, since they cannot flow out through the outlet for the ground material which is at a higher level, or additional solvent may be added from above in order. to keep the apertures in the separating sieve clear.
  • the conical shape in conjunction with the conical form of the lower part of the separating ring and the agitator shaft, ensures that the grinding particles stirred by the agitator circulate in vertical planes and do not build up as they may if the sieve lies in a horizontal plane.
  • FIG. 1 is a sectional elevation of the upper part of an agitator mill
  • FIG. 2A shows an axial sectional view of a second embodiment of the gasket
  • FIG. 2B shows a fragmentary side elevational view of the gasket of FIG. 2A
  • FIG. 2C shows a partial top plan view of the gasket of FIG. 2A
  • FIG. 3 is a bottom plan view of the sealing disc employed in FIG. 1;
  • FIG. 4 is a sectional elevation of a further modified form of sealing disc
  • FIG. 5 is a plan view of a further modification of the sealing disc
  • FIG. 6 is a vertical section through the sealing disc illustrated in FIG. 5 and adjacent parts of the agitator mill;
  • FIG. 7 is a plan view of another modification of the sealing disc.
  • FIG. 8 is a vertical section through the sealing disc shown in FIG. 7 and adjacent parts of the agitator mill which has, also, in part, been modified.
  • the agitator mill of which the upper part is shown in FIG. 1 has a double-walled grinding container of which the outer shell 1 and the inner shell 2 are of coaxial vertical circular cylindrical form.
  • the grinding space 3 enclosed by the inner shell 2 is bounded at the top by a separating sieve 4 which serves to retain the grinding particles 30.
  • the separating sieve 4 is of slightly conical form and is clamped at its outer edge between the upper end face of the grinding container 1, 2 and the cylindrical outer wall 5 of an outlet chamber 6 provided above the separating sieve 4; the outer wall 5 has an outwardly projecting flange 7 which is bolted to the upper end face of the grinding container.
  • the outlet chamber is closed by a cover 8 bolted to its outer wall 5.
  • the charge of grinding particles 30 is agitated by agitating means 12 on an agitator shaft 13 which projects vertically from above coaxially through the outlet chamber 6 and the separating sieve 4, to stir the grinding particles 30 and the material to be ground.
  • the agitator shaft 13, at the point where it passes through the cover 8 of the outlet chamber 6, carries a sealing disc 14 made from metal, which is axially adjustable in such a way as to leave a thin sealing clearance between its upper side and the underside of the cover 8.
  • the sealing disc 14 extends radially to a point close to the peripheral wall 5 of the discharge member 6, from which it is also spaced by a narrow clearance.
  • the sealing disc 14. has a hub 15 extending through the opening in the cover 8 and formed with a recess 15a into which the margin of the opening projects with slight clearance on the upper side and underside.
  • the cover 8 On its upper face the cover 8 is formed with an upstanding cylindrical sleeve 17 forming a cup 16 which can be filled with asealing fluid, e.g. a fluid to prevent evaporation of solvent from the ground material.
  • asealing fluid e.g. a fluid to prevent evaporation of solvent from the ground material.
  • the top of the cup 16 can be closed by a cover (not shown) if a pressurized gas, for-example, an inert gas, is to be introduced into the sealing gap from above.
  • each pump vane 18 has a base formed with slots 19 and 20 approximately at right angles to oneanother, by which screws 21 secure it to the underside of the sealing disc 14.
  • some or all of the pump vanes 18 may have apertures 22 as shown in FIG. 4.
  • the agitator shaft 13 carries a separating device 24, consisting of a lower separating ring 24 and an upper separating ring 25.
  • the separating rings 24 and 25 project on the upper and lower sides of the separating sieve 4 radially'beyond its inner periphery with a clearancewhich is smaller than the radius (or smaller clearance between this sleeve and the margin of the opening in the'sieve may be greater than the lower axial clearance between the separating sieve 4 and the lower separating ring 24, so that the agitator shaft 13 has adequate radial clearance;
  • the lower separating ring 24 is secured inposition by an upper lock nut 27.
  • the lower face of the lower separating ring 24 is conical in order not to interfere with circulation of the contents of the grinding container.
  • An agitator mill comprising a container for a material to be ground and particles for grinding the material, an outlet chamber spaced apart from said container by a separator and communicating with said container through said separator which allows passage of only ground material, agitating means for stirring the contents of the container, the agitating means being mounted on a shaft passing through said separator and through said outlet chamber and out through an opening in an opposed wall of said outlet chamber, and a hydrodynamic seal in the form of a rotary body mounted coaxially with the shaft in said outlet chamber to rotate with the shaft in sealing relationship with said opening and having a sealing surface separated from the inner surface of the said opposed wall of the outlet chamber by a small clearance.
  • sealing body is in the form of a disc having a plane sealing surface facing a plane surface of said opposed wall of the outlet chamber.
  • a mill as claimed in claim 2 in which the shaft is mounted substantially vertically and passes out through the top wall of the outlet chamber which is situated above the container, the container being of circular section coaxial with the shaft.
  • a mill as claimed in claim 2 in which the outlet chamber is cylindrical and the sealing disc extends to a point close to its peripheral wall.
  • a mill as claimed in claim 2 in which the surface of the sealing disc facing the wall of the outlet chamber is provided with annular ribs coaxial with the shaft and projecting into grooves in the wall of the outlet chamber, or vice versa.
  • a mill as claimed in claim 3 including a labyrinth seal in the opening in the wall of the outlet chamber where the shaft passes through it.
  • a mill as claimed in claim 2 in which the sealing disc and wall of the outlet chamber are divided so that they can be removed from the shaft to give access to the outlet chamber.
  • a mill as claimed in claim 3 in which the top wall of the outlet chamber has on it a cup surrounding the agitator shaft to receive a sealing fluid.
  • a mill as claimed in claim 10 in which the cup is closed by a cover sealed in relation to the shaft to be capable of holding the sealing fluid under pressure.
  • a mill as claimed in claim 2 in which the sealing body carries pump vanes arranged to relieve the pressure on the sealing clearance by directing medium away from it.
  • a mill as claimed in claim 12 in which the shaft and separator are provided with a separating structure comprising a sleeve mounted on the shaft with radial clearance relatively to the opening in the separator, and flanges projecting radially beyond the margin of the said opening and spaced from it by a distance smaller than the radius of the smallest grinding particles employed.
  • a mill as claimed in claim 16 in which the upper and lower flanges of the separating unit are axially adjustable relatively to the shaft.

Landscapes

  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Crushing And Grinding (AREA)
  • Mixers With Rotating Receptacles And Mixers With Vibration Mechanisms (AREA)
US00296526A 1971-10-14 1972-10-11 Agitator mill Expired - Lifetime US3817461A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2151246A DE2151246C3 (de) 1971-10-14 1971-10-14 Rührwerksmühle

Publications (1)

Publication Number Publication Date
US3817461A true US3817461A (en) 1974-06-18

Family

ID=5822350

Family Applications (1)

Application Number Title Priority Date Filing Date
US00296526A Expired - Lifetime US3817461A (en) 1971-10-14 1972-10-11 Agitator mill

Country Status (9)

Country Link
US (1) US3817461A (de)
AT (1) AT329953B (de)
BE (1) BE790105A (de)
CH (1) CH543307A (de)
DE (1) DE2151246C3 (de)
FR (1) FR2157432A5 (de)
GB (1) GB1404605A (de)
IT (1) IT972191B (de)
NL (1) NL7213826A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4089473A (en) * 1975-10-15 1978-05-16 Gebruder Netzsch, Maschinenfabrik Agitator mill
US20040032792A1 (en) * 2002-07-16 2004-02-19 Masakazu Enomura Processing apparatus and method for fluid, and deaerator therewith
US10500591B2 (en) 2015-09-02 2019-12-10 Air Products And Chemicals, Inc. System and method for the preparation of a feedstock
CN111801165A (zh) * 2018-03-07 2020-10-20 布勒股份公司 搅拌磨

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2594213B2 (ja) * 1992-03-25 1997-03-26 株式会社奈良機械製作所 粒子状材料処理装置
CN102489362A (zh) * 2011-12-26 2012-06-13 吴江德邦科技化工有限公司 一种研磨机

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3720379A (en) * 1964-10-30 1973-03-13 A Szegvari Treatment of dispersions

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3720379A (en) * 1964-10-30 1973-03-13 A Szegvari Treatment of dispersions

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4089473A (en) * 1975-10-15 1978-05-16 Gebruder Netzsch, Maschinenfabrik Agitator mill
US20040032792A1 (en) * 2002-07-16 2004-02-19 Masakazu Enomura Processing apparatus and method for fluid, and deaerator therewith
US7131604B2 (en) * 2002-07-16 2006-11-07 M. Technique Company, Ltd. Processing apparatus and method for fluid, and deaerator therewith
US20060266847A1 (en) * 2002-07-16 2006-11-30 Masakazu Enomura Processing apparatus and method for fluid, and deaerator therewith
US7278592B2 (en) 2002-07-16 2007-10-09 M Technique Co., Ltd. Processing apparatus and method for fluid, and deaerator therewith
US10500591B2 (en) 2015-09-02 2019-12-10 Air Products And Chemicals, Inc. System and method for the preparation of a feedstock
CN111801165A (zh) * 2018-03-07 2020-10-20 布勒股份公司 搅拌磨

Also Published As

Publication number Publication date
IT972191B (it) 1974-05-20
NL7213826A (de) 1973-04-17
DE2151246C3 (de) 1979-11-29
AT329953B (de) 1976-06-10
CH543307A (de) 1973-10-31
DE2151246A1 (de) 1973-04-19
BE790105A (fr) 1973-02-01
ATA877172A (de) 1975-08-15
FR2157432A5 (de) 1973-06-01
GB1404605A (en) 1975-09-03
DE2151246B2 (de) 1975-03-13

Similar Documents

Publication Publication Date Title
US3311310A (en) Stirring mill
US7014134B2 (en) Stirred ball mill
US20060261201A1 (en) Circulation type media agitator mill
US3817461A (en) Agitator mill
US3327953A (en) Sealing means for rotary agitator of a grinding and dispersing mill
JP2014042867A (ja) 循環型メディア撹拌ミル
JP3222139U (ja) ビーズミル
US3423075A (en) Mixing device
JP2009240887A (ja) メディア混合式ミル
JP5046557B2 (ja) メディア攪拌型湿式分散機及び微粒子の分散方法
JP2006212488A (ja) 媒体攪拌型粉砕装置
US3545687A (en) Media mill
JPH04243554A (ja) 予め液体内に分散させた固体を粉砕および細砕するためのミル
JP4953805B2 (ja) 媒体攪拌型粉砕装置
US3802633A (en) Apparatus for dispersing finely divided solid particles in a liquid vehicle
US6565024B2 (en) Dispersing device
US2621860A (en) Feed plate for gyratory crushers
US8733677B1 (en) Deterring wear at a bearing construct in a basket media mill
US3848816A (en) Milling machines
US3672580A (en) System for feeding grinding media to continuous attrition mill
JP7429039B2 (ja) 湿式ビーズミル
US3352500A (en) Apparatus for the production of aqueous dispersions of solids insoluble in water
JP3802951B2 (ja) 粉砕機
JP2005199125A (ja) メディア攪拌ミル
JP2000254535A (ja) 混練粉砕機