WO1988003439A1 - Locking ring for centrifugal separator - Google Patents

Locking ring for centrifugal separator Download PDF

Info

Publication number
WO1988003439A1
WO1988003439A1 PCT/SE1987/000512 SE8700512W WO8803439A1 WO 1988003439 A1 WO1988003439 A1 WO 1988003439A1 SE 8700512 W SE8700512 W SE 8700512W WO 8803439 A1 WO8803439 A1 WO 8803439A1
Authority
WO
WIPO (PCT)
Prior art keywords
locking ring
rotor
fibres
sleeve
end portion
Prior art date
Application number
PCT/SE1987/000512
Other languages
French (fr)
Inventor
Ingvar HÄLLGREN
Original Assignee
Alfa-Laval Separation Ab
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 Alfa-Laval Separation Ab filed Critical Alfa-Laval Separation Ab
Publication of WO1988003439A1 publication Critical patent/WO1988003439A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B7/00—Elements of centrifuges
    • B04B7/08—Rotary bowls
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04B—CENTRIFUGES
    • B04B1/00—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles
    • B04B1/10—Centrifuges with rotary bowls provided with solid jackets for separating predominantly liquid mixtures with or without solid particles with discharging outlets in the plane of the maximum diameter of the bowl

Definitions

  • the present invention concerns a centrifugal separator with a rotor of the kind which comprises a first circular rotor part with a sleeve like end portion, a second rotor part with an annular edge portion arranged coaxially with the sleeve formed end portion, and a locking ring, which at least partly is inserted in said sleeve like end portion and abuts axially against the edge portion, the sleeve like end portion having internal threads and the locking ring having external threads engaging each other, whereby the locking ring is arranged to keep the rotor part axially together against forces tending to bring the rotor parts apart.
  • the object of the present invention is to obtain an improved engagement between the locking ring and the sleeve like end portion of said one rotor part in a centrifugal separator of the king initially described, without rendering it more difficult to mount and dismount the locking ring.
  • the centrifugal separator gives the following characteristics: 1) that the locking ring is made of a material comprising a matrix, which is deformable in the circumferential direction of the locking ring as a result of the rotation of the rotor, and reinforcing fibres, such as glass fibres, embedded in the matrix, a first part of said fibres being so oriented that they extend essentially in the circumferential direction of the locking ring and a second part having a radial extension and extending out in the threads of the locking ring, 2) that the amount and the distribution of the fibres are so chosen that the locking ring is elastically deformed in the circumferential direction as a result of the rotation of the rotor as much as admitted by the surrounding sleeve like end portion of the first rotor part, 3) that the first rotor part is so designed, that the deformation in the circumferential direction of its sleeve like end portion as a result of the rotation of the rotor is kept within the
  • annular edge portion of the said second rotor part has been inserted into the sleeve like end portion past the threads of the same, before the locking ring is inserted to abutment against the annular edge portion, in a way such that the part of the locking ring taking up the forces is located axially between the annular edge portion and the threads in the sleeve formed end portion.
  • fig. 1 shows a known centrifuge rotor of the kind here in question
  • fig. 2 shows an enlargement of a part of fig. 1 but with a locking ring according to the invention
  • fig. 3 shows schematically a number of layers of material, which can be included in a locking ring according to the invention.
  • a centrifuge rotor comprising two circular rotor parts 1 and 2, which at their circumference are kept together axially by means of a locking ring 3.
  • a separation chamber 4 is formed, in which two components of a liquid mixture are to be separated upon rotation of the rotor.
  • a liquid pressure is created in the separation chamber 4, which tends to press the rotor parts 1 and 2 axially apart.
  • the rotor has a vertical driving shaft 5 connected to the rotor part 1.
  • the centrifuge rotor in fig. 1 is designed according to conventional technique. Any more detailed description of the same is not necessary for the understanding of the present invention.
  • fig. 2 there is shown an enlarged part of fig. 1.
  • the rotor part 1 has a sleeve like portion 6 with internal threads, which is located in engagement with external threads on the locking ring 3.
  • the rotor part 2 has an annular edge portion 7, which is axially inserted into the sleeve like end portion 6 to abutment against a shoulder 8 of the rotor part 1.
  • the locking ring 3 is screwed into the sleeve formed end portion 6 to axial abutment against the annular edge portion 7.
  • the locking ring 3 is built up by a number of thin annular layers. Each such layer consists of a sheet of fibres, which is embedded into plastic. The different layers, which from the beginning have been quadrangular or circular, have been melt together to a body out of which a ring has been cut out and finally been machined for the shaping of the external threads.
  • fig. 3 there is illustrated four pieces of layers of the described kind, which may be a part of a locking ring 3.
  • the layers are denoted in fig. 3 with the letters a - d.
  • a first number of fibres extend in the circumferential direction of the annular layer and a second number of fibres essentially radially.
  • certain fibres extend parallelly to a direction x and the other fibres parallelly to another direction y perpendicular to the direction x.
  • the fibres extend as in the layer c, but all the layer d is turned to an angle ⁇ relative to the layer c around a central axis z .
  • a locking ring 3 By melting together a number of layers of the same or different kind a locking ring 3 can be provided with the exact wanted characteristics concerning density, strength and elastic deformabillty in different direction.
  • the thickness of each layer can be varying. On the market there is available for instance layers consisting of glass fibres embedded in eppxi-plastic, which layers have a thickness of between 0.1 and 2.0 mm.
  • the wanted characteristics of a locking ring 3 are such, that the locking ring during the rotation of the centrifuge rotor will be elastically deformed as a result of the centrifugal force to abutment radially against the inside of the sleeve like end portion 6 of the rotor part 1. Thereby a satisfactory engagement is obtained during operation between the threads of the locking ring 3 and the end portion 6, respectively.
  • the end portion 6 has to be designed such that it can be deformed less than the locking ring 3 in radial direction. If wanted the end portion 6 can have an external strengthening sleeve of the kind that is suggested in U.S. 4,160,521, but this is not necessary.
  • the locking ring has lower density than the sleeve like end portion 6 of the rotor.
  • the locking ring can in an effective manner take up the shear and bending forces occurring in the same during operation.
  • a locking ring built up in the manner described above gets a rather low strength against tensile forces in axial direction.
  • a locking joint Depending on how a locking joint is designed a need, therefore, can arise for strengthening of the strength of the locking ring in axial direction.
  • the locking ring joint shown in the drawing is of this kind.
  • glass fibres and carbon fibres are possible in a locking ring according to the invention. For instance, it is possible to combine fibres of both these types in the same locking ring by melting together layers containing different types of fibres.

Landscapes

  • Centrifugal Separators (AREA)

Abstract

In a centrifuge rotor an annular locking ring (3) is arranged to by means of external threads engage with internal threads in a sleeve like portion (6) of a rotor part (1) and thereby to join this rotor part axially to another rotor part (2). According to the invention the locking ring (3) is made of a composite material comprising a matrix and fibres embedded in this. A first part of fibres extending essentially in the circumferential direction of the locking ring and a second part of fibres extending essentially radially and out in the threads of the locking ring. The amount and the distribution of the fibres are so chosen that the locking ring (3) is elastically deformed in the circumferential direction upon rotation of the rotor as much as admitted by the surrounding sleeve like end portion (6). Thereby it is achieved both that the centrifuge rotor easily can be assembled and disassembled, when it is out of operation, and that a satisfactory engagement during operation can be established between the locking ring (3) and the sleeve like end portion (6), the fibres extending radially taking up axially directed shear and bending forces in the locking ring (3).

Description

Locking Ring for Centrifugal Separator
The present invention concerns a centrifugal separator with a rotor of the kind which comprises a first circular rotor part with a sleeve like end portion, a second rotor part with an annular edge portion arranged coaxially with the sleeve formed end portion, and a locking ring, which at least partly is inserted in said sleeve like end portion and abuts axially against the edge portion, the sleeve like end portion having internal threads and the locking ring having external threads engaging each other, whereby the locking ring is arranged to keep the rotor part axially together against forces tending to bring the rotor parts apart.
In a centrifugal separator of this kind there is a problem during operation to maintain a maximum engagement between the external threads of the locking ring and the internal threads of said sleeve like end portion of the one rotor part. Because of the fact that the sleeve like end portion is located at a larger radius and consequently during operation in a stronger g-field than the locking ring, the end portion will be deformed more than the locking ring if these details, wlch is customary, are made of the same material. Thereby, a bigger gap between these details arises during operation than at standstill with accompanying deteriorated engagement between the threads. A certain radial gap between the locking ring and the sleeve like end portion is necessary at standstill for the facilitation of the mounting of the locking ring.
The circumstances just described put a certain limit for how fast a centrifuge rotor of the described kind can be rotated, because only a certain maximum gap can be tolerated between the locking ring and the sleeve formed portion for the maintenance of a secure engagement them between.
To make a higher rotational speed possible for a centrifuge rotor it has been suggested earlier (see U.S. 4,160,521) to provide the sleeve like end portion with a surrounding sleeve of a relatively light composite material containing strong fibres, e.g. carbon fibres, which are oriented in the circumferencial direction of the rotor. However, such a sleeve is rather difficult to mount, while it has to be mounted with a certain prestress around the sleeve like end portion. Because of the fact that not only the sleeve like end portion but also the locking ring then will be prestressed, it becomes necessary in practice to disassemble and reassemble the reinforcing sleeve at each occasion the rotor is to be taken apart. To prestress only the sleeve like end portion and to adapt the size of the locking ring to the prestressed end portion would be possible per se, but should only marginally make higher rotational speeds possible for the centrifuge rotor. This depends on the fact that existing composite materials of the kind, which are possible in this case, in spite of the fact that they possess great strength, are more stretchable than metal, out of which centrifugal rotors normally are made. However, since metal has substantially higher density than such composite materials , a reinforcing sleeve of composite material would not be able to prevent an unwanted radial extension of a non-prestressed locking ring of metal beyond its limit for elastic deformation (the yield point) as a result of centrifugal forces acting on the locking ring. The larger strength, which could be obtained in the sleeve like end portion of the centrifuge rotor by prestressing the same by means of a surrounding sleeve of composite material, thus could not be utilized by use of a non- prestressed locking ring of metal without this being subjected to a plastic (permanent) deformation during the rotation of the centrifuge rotor.
The object of the present invention is to obtain an improved engagement between the locking ring and the sleeve like end portion of said one rotor part in a centrifugal separator of the king initially described, without rendering it more difficult to mount and dismount the locking ring. This can be obtained according to the invention by giving the centrifugal separator the following characteristics: 1) that the locking ring is made of a material comprising a matrix, which is deformable in the circumferential direction of the locking ring as a result of the rotation of the rotor, and reinforcing fibres, such as glass fibres, embedded in the matrix, a first part of said fibres being so oriented that they extend essentially in the circumferential direction of the locking ring and a second part having a radial extension and extending out in the threads of the locking ring, 2) that the amount and the distribution of the fibres are so chosen that the locking ring is elastically deformed in the circumferential direction as a result of the rotation of the rotor as much as admitted by the surrounding sleeve like end portion of the first rotor part, 3) that the first rotor part is so designed, that the deformation in the circumferential direction of its sleeve like end portion as a result of the rotation of the rotor is kept within the limits for an essentially elastic deformation of the locking ring, and 4) that the said second part of the fibres is arranged to take up axially directed shear and bending forces occurring in the threads of the locking ring during operation of the rotor.
By this invention it is possible, with or without special reinforcement of the sleeve like end portion, to obtain a maximum engagement between the threads of the same and the threads of the locking ring upon rotation of the centrifuge rotor. Upon need already existing centrifugal separators can be equipped with locking rings of the type in question.
For avoiding axial tensile forces in the locking ring it is suitable, as is already customary, that the annular edge portion of the said second rotor part has been inserted into the sleeve like end portion past the threads of the same, before the locking ring is inserted to abutment against the annular edge portion, in a way such that the part of the locking ring taking up the forces is located axially between the annular edge portion and the threads in the sleeve formed end portion.
The invention will be described more in detail In the following with reference to the accompanying drawing. In this fig. 1 shows a known centrifuge rotor of the kind here in question, fig. 2 shows an enlargement of a part of fig. 1 but with a locking ring according to the invention, and fig. 3 shows schematically a number of layers of material, which can be included in a locking ring according to the invention.
In fig. 1 there is shown a centrifuge rotor comprising two circular rotor parts 1 and 2, which at their circumference are kept together axially by means of a locking ring 3. Within the rotor a separation chamber 4 is formed, in which two components of a liquid mixture are to be separated upon rotation of the rotor. Upon operation of the rotor a liquid pressure is created in the separation chamber 4, which tends to press the rotor parts 1 and 2 axially apart. The rotor has a vertical driving shaft 5 connected to the rotor part 1.
The centrifuge rotor in fig. 1 is designed according to conventional technique. Any more detailed description of the same is not necessary for the understanding of the present invention.
In fig. 2 there is shown an enlarged part of fig. 1. As can be seen the rotor part 1 has a sleeve like portion 6 with internal threads, which is located in engagement with external threads on the locking ring 3.
The rotor part 2 has an annular edge portion 7, which is axially inserted into the sleeve like end portion 6 to abutment against a shoulder 8 of the rotor part 1. The locking ring 3 is screwed into the sleeve formed end portion 6 to axial abutment against the annular edge portion 7.
As illustrated in fig. 2 the locking ring 3 is built up by a number of thin annular layers. Each such layer consists of a sheet of fibres, which is embedded into plastic. The different layers, which from the beginning have been quadrangular or circular, have been melt together to a body out of which a ring has been cut out and finally been machined for the shaping of the external threads.
In fig. 3 there is illustrated four pieces of layers of the described kind, which may be a part of a locking ring 3. The layers are denoted in fig. 3 with the letters a - d.
In the layer a a first number of fibres extend in the circumferential direction of the annular layer and a second number of fibres essentially radially.
In the layer b relative short fibres are distributed, extending in all (arbitrary) directions.
In the layers c certain fibres extend parallelly to a direction x and the other fibres parallelly to another direction y perpendicular to the direction x.
In the layer d the fibres extend as in the layer c, but all the layer d is turned to an angle α relative to the layer c around a central axis z .
Other patterns for the extension of the fibres in a layer of this kind are possible.
By melting together a number of layers of the same or different kind a locking ring 3 can be provided with the exact wanted characteristics concerning density, strength and elastic deformabillty in different direction. The thickness of each layer can be varying. On the market there is available for instance layers consisting of glass fibres embedded in eppxi-plastic, which layers have a thickness of between 0.1 and 2.0 mm.
The wanted characteristics of a locking ring 3 are such, that the locking ring during the rotation of the centrifuge rotor will be elastically deformed as a result of the centrifugal force to abutment radially against the inside of the sleeve like end portion 6 of the rotor part 1. Thereby a satisfactory engagement is obtained during operation between the threads of the locking ring 3 and the end portion 6, respectively. Thus, the end portion 6 has to be designed such that it can be deformed less than the locking ring 3 in radial direction. If wanted the end portion 6 can have an external strengthening sleeve of the kind that is suggested in U.S. 4,160,521, but this is not necessary. Preferably the locking ring has lower density than the sleeve like end portion 6 of the rotor.
Because of the fact that an essential number of fibres extend from the body of the locking ring out in the threads of the locking ring, the locking ring can in an effective manner take up the shear and bending forces occurring in the same during operation.
A locking ring built up in the manner described above gets a rather low strength against tensile forces in axial direction. Depending on how a locking joint is designed a need, therefore, can arise for strengthening of the strength of the locking ring in axial direction. To avoid such a need it is suitable to utilize a locking joint of previously conventional kind, at which the locking ring besides the shear and bending forces is subjected to essentially axial pressure forces. The locking ring joint shown in the drawing is of this kind. In the above it has been mentioned that glass fibres and carbon fibres are possible in a locking ring according to the invention. For instance, it is possible to combine fibres of both these types in the same locking ring by melting together layers containing different types of fibres.
One example of characteristics in a locking ring built up according to the invention can be according to the following:
Density (ρ) 2500 kg/m3. Coefficient of elasticity (E)
16.000 N/mm2. Yield point (σ), i.e. the limit for elastic (non-permanent) deformation, 350 N/mm2. The values above for E and σ concern the circumferential direction of the locking ring. As a comparison the following corresponding values can be given for two different materials, of which the rotor body itself can be built namely stainless steel P - 7800 kg/m3, E = 210.000 N/mm2, σ = 450 N/mm2 respectively an alloy of titanium ρ = 4400 kg/m3, E = 110.000 N/mm2, σ = 950
N/mm2.
Also other kinds of fibres and other kinds of matrix but plastic are possible. It is thus possible to make a locking ring in principally the same manner as described above of a metal or an alloy of metal contalng fibres of for instance carbon or silicon carbide.

Claims

Claims
1. Centrifugal separator with a rotor comprising a first circular rotor part (1) with a sleeve like end portion (6), a second rotor part (2) with an annular edge portion (7) arranged coaxially with the sleeve formed end portion (6), and a locking ring (3), which at least partly is inserted in said sleeve like end portion (6) and abuts axially against said annular edge portion (7), the sleeve like end portion (6) having internal threads and the locking ring (3) having external threads engaging each other, whereby the locking ring (3) is arranged to keep the rotor parts (1, 2) axially together against forces tending to bring the rotor parts apart, c h a r a c t e r i z e d i n
- that the locking ring (3) is made of a material comprising a matrix, which is deformable In the circumferential direction of the locking ring as a result of the rotation of the rotor, and reinforcing fibres, such as glass fibres, embedded in the matrix, a first part of said fibres being so oriented that they extend essentially in the circumferential direction of the locking ring and a second part having a radial extension and extending out in the threads of the locking ring,
- that the amount and the distribution of the fibres are so chosen that the locking ring (3) is elastlcally deformed in the circumferential direction as a result of the rotation of the rotor as much as admitted by the surrounding sleeve like end portion (6) of the first rotor part (1),
- that the first rotor part (1) Is so designed, that the deformation in the circumferential direction of its sleeve like end portion (6) as a result of the rotation of the rotor is kept within the limits for an essentially elastic deformation of the locking ring (3), and - that the said second part of the fibres is arranged to take up axially directed shear and bending forces occurring in the threads of the locking ring during operation of the rotor.
2. Centrifugal separator according to claim 1, c h a r a c t e r i z e d i n that the locking ring (3) is composed of a number of concentric, essentially plane layers, in which the said fibres extend.
3. Centrifugal separator according to claim 2, c h a r a c t e r i z e d i n that fibres in at least one layer extend annularly in the circumferential direction of the locking ring (a).
4. Centrifugal separator according to claim 2 or 3, c h a r a c t e r i z e d i n that fibres in at least one layer extend in essentially all directions (b).
5. Centrifugal separator according to any of the claims 2-4, c h a r a c t e r i z e d i n that fibres in each one of at least two equal layers (c, d) extend essentially in a small number of determined directions, the one layer (d) being turned a certain angle ( α ) relative to the other (c).
PCT/SE1987/000512 1986-11-04 1987-11-02 Locking ring for centrifugal separator WO1988003439A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8604712A SE455272B (en) 1986-11-04 1986-11-04 LASRING FOR A CENTRIFUGROTOR
SE8604712-3 1986-11-04

Publications (1)

Publication Number Publication Date
WO1988003439A1 true WO1988003439A1 (en) 1988-05-19

Family

ID=20366186

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1987/000512 WO1988003439A1 (en) 1986-11-04 1987-11-02 Locking ring for centrifugal separator

Country Status (2)

Country Link
SE (1) SE455272B (en)
WO (1) WO1988003439A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5062826A (en) * 1989-07-14 1991-11-05 Marco Mantovani Device for locking a blood centrifugation cell on a chuck
US6432034B1 (en) * 1999-03-09 2002-08-13 Alfa Laval Ab Looking ring for a centrifugal separator
US8808154B2 (en) * 2010-09-13 2014-08-19 Hiller Gmbh Drive apparatus in a scroll centrifuge having a gearbox with a housing nonrotatably connected to a drive shaft

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB403749A (en) * 1932-07-13 1934-01-04 Perfect Tape Coupler Company L An improvements in or relating to knot-tying devices
US4000665A (en) * 1975-08-26 1977-01-04 The Johns Hopkins University Woven filament rotor structure
US4098142A (en) * 1975-11-14 1978-07-04 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Rotatable mass for a flywheel

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB403749A (en) * 1932-07-13 1934-01-04 Perfect Tape Coupler Company L An improvements in or relating to knot-tying devices
US4000665A (en) * 1975-08-26 1977-01-04 The Johns Hopkins University Woven filament rotor structure
US4098142A (en) * 1975-11-14 1978-07-04 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Rotatable mass for a flywheel

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5062826A (en) * 1989-07-14 1991-11-05 Marco Mantovani Device for locking a blood centrifugation cell on a chuck
AU619994B2 (en) * 1989-07-14 1992-02-06 Dideco S.R.L. Device for locking a blood centrifugation cell on a chuck
US6432034B1 (en) * 1999-03-09 2002-08-13 Alfa Laval Ab Looking ring for a centrifugal separator
US8808154B2 (en) * 2010-09-13 2014-08-19 Hiller Gmbh Drive apparatus in a scroll centrifuge having a gearbox with a housing nonrotatably connected to a drive shaft

Also Published As

Publication number Publication date
SE8604712D0 (en) 1986-11-04
SE455272B (en) 1988-07-04
SE8604712L (en) 1988-05-05

Similar Documents

Publication Publication Date Title
US4660435A (en) Fiber composite flywheel rim
US5901616A (en) Inertial mass for vibration isolators
US5888140A (en) Torsionally stiff, flexible shaft coupling, especially one made entirely of steel
CN101107455A (en) Elastic articulated mechanism
KR920000974B1 (en) Resilient shaft coupling
US4306836A (en) Hub assembly
US3427826A (en) Quick disconnect flexible couplings and hub mountings
GB2154301A (en) A powdered metal, flanged bushing for securing machine elements to shafts
US3901047A (en) Resilient coupling
US4063433A (en) Elastic rotational couplings
WO1988003439A1 (en) Locking ring for centrifugal separator
IL46018A (en) Elastic friction coupling
EP0136963A2 (en) Composite flexible pulp refiner disk and method of making same
EP0642635B1 (en) A fly wheel arrangement
KR20160085715A (en) A rotorcraft rotor comprising a hub made of composite materials obtained from carbon fiber fabric dusted in a thermoplastic resin
CA1087862A (en) Flexible spherical joint
EP0182902B1 (en) Centrifugal separator
US4732337A (en) Meat chopper blade head
GB2166843A (en) Super-resilient shaft coupling
US5295912A (en) Resilient shaft coupling designed as a composite part and method of producing it
EP0164013A1 (en) Elastomeric shear shaft coupling
JPH0299701A (en) Mechanism for detachably bonding rotor body with hollow shaft
GB2168452A (en) Tubular member composed of a polymeric material
US4150582A (en) Rotor ring for inertial energy storage rotor
JPS6137477B2 (en)

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): JP US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE FR GB IT LU NL SE