JPS63319073A - Mixed centrifugal separator rotor and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to an ultracentrifuge rotor used for ultrahigh-speed centrifugation, and in particular, the present invention relates to an ultracentrifuge rotor for use in ultrahigh-speed centrifugation. It relates to a rotor made of a hybrid material surrounded by a ring made of another material.

BACKGROUND OF THE INVENTION Ultracentrifuge rotors encounter extreme stresses as increasingly higher speeds require their application for new and increasingly complex scientific experiments. High capacity, high speed rotors generally have large fixed angles, and straight tube rotors have high kinetic energy. High stresses occur in high speed, high energy rotors, making material selection critical in design. For this reason, titanium is the isotropic material most often chosen for high speed, high capacity rotor designs.

Conventional high kinetic energy rotors capable of high speed operation are typically constructed from isotropic titanium with a density of about 0.161 b/in3. Titanium is a hard metal, difficult to process due to its density, and also very expensive. Furthermore, increasing speed requires increasing strength, so the kinetic energy that a titanium rotor withstands is
The strength of the metal material, which increases proportionally to the square of its density and the rotational speed at which the rotor is driven, cannot be effectively improved by increasing the size, diameter or thickness of the rotor.

In the past, centrifuge rotors have been constructed from ++1 layered fiber resin shells for low speed applications, which have been found to be more reliable than other all-metal designs.

U.S. Pat. No. 3,993,243 to Ditzel has a metal bottom and a top made of a circular metal plate! This is a typical example of a centrifugal drum shell made from a laminated material of a-fiber and resin. The metal plate has a flange that attaches it to the centrifuge drum shell by means of tightening screws. The drum shell has a multilayer cross-sectional configuration that includes the use of axially extending wire and wide mesh backing strainers. This configuration, including fasteners, is suitable for low speeds, but does not withstand the stresses caused by very high speeds.

Similarly, a laminated material rotor made of steel coated resin plastic material is disclosed in U.S. Pat. No. 3,997,106 for a drum. One embodiment of this patented invention discloses the use of piano wire surrounding a perforated steel strip covering an inner body of cast plastic resin material. This configuration is useful for centrifuge rotors used for low speed liquid separation, but does not withstand high speed stresses.

No. 4,160,512 to Ringgren discloses the manufacture of fiber reinforced rotors for use in centrifuges, vanes, generators and flywheels.

The rotor shell consists of an outer layer made of fiber-wrapped filaments wrapped around an intermediate sleeve of plastic resin or aluminum. This outer layer forms a fiber laminate member that prestresses the inner intermediate sleeve. Said outer layer is secured to the inner intermediate sleeve by pressure wrapping of the outer layer onto the inner sleeve. This winding under pressure prestresses the inner sleeve and slightly reduces its diameter.As a result of mechanically prestressing the inner sleeve, the reinforcing rotor is made of metal. This patent teaches that a sleeve-only rotor can operate at such speeds that the stiffness would deform or destroy the surface at high speeds. Temperature "shrink fit J st" maintains a low temperature in the internal metal part while the laminated sleeve is applied to the metal part.
+r inkage f i L is mentioned. This US patent provides only limited reduction in temperature and
The high pressure between the fiber-reinforced sleeve and the metal component is said to be obtained when the internal component returns to room temperature. This US patent teaches counteracting temperature "shrink fit." This US patent is based on J1 always low 7:n! Lack of awareness of the possibility of effective contraction through the use of excessive amounts.

Thus, U.S. Pat. It teaches the concept of eliminating pre-stress on the sleeve.

Both U.S. Pat. No. 4,468,269 to Curley and U.S. Pat. No. 3,913.828 to Roy disclose a plurality of "" Discloses an ultracentrifuge rotor configuration that includes a pre-loaded ring.

The rings are interleaved with a thin epoxy coating between each of the rings. Said rings are made by winding around mandrels having different diameters, said diameters being evenly spaced within the range of 10 to 15 layers for each ring section.
% filament. By assembling said rings in thin sections and then preforming said rings with each other, it is possible to achieve a rotor structure in which the filament density outside said rings is equal to the density inside said rings. . The pre-fitted polymer ring is epoxied to the covering wall and pressed against the wall using a small pressure exerted in the axial direction.

The final structure is heat cured. The structure has a heat cured epoxy layer to reinforce the central wall structure, the wall being selected from titanium, aluminum or heat treated steel.

None of the conventional hybrid rotor configurations are directed towards single-shell bodies and do not simplify the reinforcement structure.

The prior art has the basic idea that both bacteriostatic and dynamic loads must be analyzed and considered when one wishes to design a multi-material rotor for ultracentrifuge applications. Not handling the problem.

Ringgren U.S. Pat. No. 4,160,512 and Curley U.S. Pat. No. 4,468,269 are directed to static loading problems, but they are not directed to dynamic loading problems for their respective configurations. do not have. Static load is the stress between the core body and the outer ring when the rotor is at rest. This static load is essential to holding the hybrid rotor assembly together at rest. However, when rotation occurs in the rotor, tangential outward stresses are created.

U.S. Patent No. 4,160,512 and U.S. Pat.
The core body of the 468,269 configuration expands at a slower rate than the outer ring, so that the outer ring does not sustain the stresses imposed on the core body during dynamic rotor operation. During dynamic loading, because the core body expands at a slower rate than the outer ring, the rings disengage from the core body and do not maintain a prestress load on the body.

Traditionally, aluminum and titanium are the materials of choice for constructing isotropic material rotors. Aluminum is only used for high speed applications if the stress experienced by the rotor filled with liquid sample is significantly less than the stress at stress break 11'J in the aluminum body. When higher capacity rotors or higher speeds are required, the rotors are traditionally able to withstand higher stresses and higher volumes of sample liquid than comparable sized and high capacity aluminum rotors.
゛ Designed using titanium, a high-density material.

Traditionally, only titanium has been able to withstand the dynamic stresses of high-speed, high-volume centrifuges. Low-density configurations, such as rings made of aluminum and composite materials, have been able to withstand the same dynamic stresses that titanium rotors are subjected to. It must be able to withstand dynamic loads.

What is required, as mentioned above, is a configuration of multiple materials that is oriented to both static and dynamic load characteristics.
This is a configuration of a jQ rotor considering +1. An outer fiber-reinforced shell, such as that shown in Ringgren U.S. Pat. creating excessive unforeseen non-uniform stresses in the core body.

What is needed is a medium-purified reinforced rotor that eliminates the need for titanium as an abrasive for ultra-high-speed rotors and uses a lighter, more machinable metal for the reinforced rotor core. It is.

(Structure of the Invention) The hybrid centrifuge rotor of the present invention has two main parts:
That is, it consists of a rotor core body and a reinforcing ring.

The rotor core body is an isotropic material such as aluminum. The reinforcing ring surrounding the rotor core body is made of an anisotropic material such as graphite fibers and epoxy resin filament wrapping material. The term "anisotropic material" as used in this specification refers to bulk modulus,
Refers to a material that has properties such as strength and hardness in a particular direction. ) The resin of the reinforcing ring is thermoplastic g2 +1 or thermosandizable. The fibers of the filament-wound ring may be made of glass or a material such as Kevlar (trade name), an organic resin fiber material manufactured by DuPont.

The isotropic rotor core body of the hybrid centrifuge rotor prestresses the filament-wrapped anisotropic reinforcing ring. The rotor core body is initially configured to be of larger diameter than the reinforcing ring. The rotor core body is then uniformly temperature-shrinked in a low-temperature environment and nested into the reinforcing ring during final assembly of the rotor, so that the rotor core body gives prestress to the reinforcing ring.

The rotor core body prestresses the reinforcing ring when the rotor core body returns to ambient or room temperature after being removed from the cold environment. This prestress occurs as the rotor core body attempts to recover its original dimensions. The low temperature environment is achieved by immersing the isotropic rotor core body in a liquid nitrogen bath. The rotor core body is
Maximum, calculated according to the formula δ = αLΔT (where δ is the amount of contraction, α is the coefficient of thermal expansion, L is the diameter of the metal rotor core body, and 6th is the temperature difference between the atmospheric temperature and the low temperature environment). will be uniformly shrunk to the specified value. The rotor core body is then immersed in a cold environment for an optimal time such that shrinkage of the core body occurs within the calculation range defined by the above formula. The rotor core body is then telescoped into the reinforcing ring at a uniform rate and then expanded at room temperature.

The anisotropic reinforcing ring surrounding the rotor core body is a conventional circumferentially wound filament in which the direction of the fiber wrap is 0 degrees from a horizontal plane descending to the base of the rotor core body. Alternatively, the filament can be wound transversely at an angle to the horizontal plane to further strengthen the reinforcing ring.

The method of manufacturing a hybrid centrifuge rotor consists of placing a rotor core body of isotropic metallic material in a low temperature environment such as liquid nitrogen, which uniformly shrinks the dimensions of the rotor core body, the rotor core body is surrounded by a reinforcing ring, and the rotor core body is surrounded by a reinforcing ring, Fitting a reinforcing ring made of anisotropic material around the shrunken rotor core body so as to fit into the reinforcing ring, returning the rotor core body assembled in the reinforcing ring to room temperature, returning the rotor core body to its original size, and reinforcing it. Including causing an interference fit to the ring. As a step of the manufacturing method, the uniform shrinkage Aj method of the rotor core body is determined by the above-mentioned formula for uniformly shrinking the rotor core body in a low-temperature environment. The reinforcing ring is preferably placed around the cryogenically treated rotor core body, but alternatively the rotor core body may be placed within the ring.

By prestressing the reinforcing ring, a strong static load is achieved due to the interference fit of the rotor core body and the reinforcing ring. The outwardly expanding rotor core body prestresses the reinforcing ring by achieving a high static load of the rotor core body relative to the M reinforcement. During rotation and dynamic loading conditions, the high tensile J-length strength hjgh modulus exhibited by the reinforcing ring tends to wrap around the core body as centrifugal forces attempt to increase within the core body.

In this way, a hybrid rotor is obtained that compensates for both static and dynamic loads.

EXAMPLE The hybrid rotor of the present invention includes two major components: an isotropic rotor core and a y-j tropic reinforcement ring. In Figure 1, /11! A longitudinal cross-sectional view of a preferred embodiment of a synthetic centrifuge rotor is shown. The isotropic rotor core body 12 is preferably constructed from aluminum and has a density of approximately 0.111 b/in3.

The metal rotor core body 12 has a weight of approximately 0.16 lb/
in' density, which is substantially less than that of conventional hollow rotors made from titanium.

An anisotropic reinforcing ring 14 surrounds the rotor core body. The reinforcing ring 14 is a cylindrical ring wrapped with graphite fibers and epoxy resin filaments. The density of the synthetic filament wrapped reinforcing ring 14 is approximately 0.061 b/in". Thus, for the vertical tube rotor body shown in FIG. The loss T' is lower than that of conventional titanium rotors.
A vertical test tube cavity 16 formed in the rotor core body 12 is shown. Also shown in FIG. 1 is a drive shaft hole 18 for receiving a drive shaft (not shown).

The construction of high-capacity centrifuge rotors operated at high speeds must meet various criteria. Stiffness criteria include rotor density and weight. The lower the density, the lower the kinetic energy produced at a given speed in a shortage situation. Light-1 as described here? The rotor substantially reduces acceleration and deceleration times, and the choice of aluminum for the rotor core body substantially reduces manufacturing costs compared to conventional titanium rotors. Traditionally, despite the cost disadvantage and processing difficulties,
Titanium's high density makes it a popular material for high-energy centrifuge rotors, as it is the only material that can withstand very high speeds when it is desired to apply and perform biological separation studies of various organic substances. selected as. The titanium rotor has high strength, but its high density
As rotor speed increases, resulting in high kinetic energy, rotor damage requires a corresponding increase in the strength and weight of the barrier ring required to accommodate the high rotational energy rotor. The hybrid rotor of the present invention is lighter and less dense than conventional titanium rotors, and therefore has lower kinetic energy than conventional titanium rotors, requires no barrier ring changes, and has a 71-sea rotor. It can withstand high speeds without creating excessive stress on the core body.

The hybrid rotor of the present invention provides a low density centrifuge rotor assembly with a rotor core body and reinforcement ring interface. Conventional multilayer material centrifuge rotor body core construction interfaces rely on prestressing the rotor core body. Traditionally, the outer ring was designed to prestress the rotor core body to provide a strong interface. However, applying prestress to the rotor core body using the conventional pressure 1/<lj law causes damage, cracks, and distortion to the rotor core body 12, and at ultra-high speeds obtained by motor drive, the rotor core body may be destroyed and ql'
This caused an 11th attack.

The present invention applies prestress to the reinforcing ring. This is 50 mm between the reinforcing ring 14 and the rotor core body 12.
This is accomplished by an interference fit without introducing outward stresses in excess of a static load of ,0OOpsi. (The term "tight fit" used in this specification)
cc fit is defined as one of the two parts (in this case the core body) when two parts fit together to form an assembly, such as the rotor core body 12 and the reinforcing ring 14.
This means that the internal stresses in the first part cause this part to exert a uniform stress on the other parts. ) The rotor core body 12 is initially designed to have a diameter somewhat larger than the inner diameter of the reinforcing ring 14. The rotor core body 12 is then placed in a low temperature environment where it is uniformly temperature shrunk such that the diameter of the rotor core body 12 is slightly smaller than the inner diameter of the reinforcing ring 14 such that the reinforcing ring 14 surrounds the rotor core body 12. , the rotor core body 2 is assembled into a complete set within the reinforcing ring 14. The rotor may alternatively be assembled by placing the core body 12 within the reinforcing ring 14. In a preferred embodiment, the rotor core body 12 is immersed in a -290° F. liquid nitrogen bath for 25 hours. Uniform shrinkage is achieved by immersing the rotor core body 12 in a liquid nitrogen bath. Maximum possible contraction 1 [''
is calculated according to the formula δ=α·LΔT. Here, δ
is the amount of shrinkage (measured in inches), α is the coefficient of thermal expansion (measured in inches relative to 'F), L is the diameter of the metal core body measured in inches, and ΔT is the low temperature environment liquid nitrogen bath (approximately -290°F)
and room temperature of about +77°F, respectively.

In a preferred embodiment, 8T is approximately -367°F. In this case, δ or shrinkage is measured in negative (-) inches.

After the maximum shrinkage is calculated, a shrinkage vs. time experimental design is performed to find the optimal length of time to immerse the rotor core body 12 in liquid nitrogen to obtain the desired shrinkage within the calculated range. It will be done.

After the rotor core body 12 has been immersed in the cold environment of liquid nitrogen for an optimum period of time, the reinforcing ring is assembled to surround the rotor core body. A fit is created between the rotor core body 12 and the reinforcing ring 14 along the intermediate cylinder 22. The intermediate fit between the rotor core body and the reinforcing ring is such that the reinforcing ring 14 merely surrounds the core body, rather than mechanically forcing the rotor core body 12 to fit within the reinforcing ring 14. This is accomplished by thermally shrink-fitting the rotor core body to a small diameter.

The intermediate surface fit described in No. 111j is achieved by taking advantage of the metal core which has a higher coefficient of thermal expansion than that of the reinforcing ring. When placed in the mating position within the cryogenically treated rotor core body or ring, the stiffening ring will first be damaged due to the residual thermal effects of the rotor core body or chamber of the very low lX. Although rapidly cooled by the rotor core body, the reinforcing ring expands more slowly than the rotor core body due to its low expansion coefficient. In other words, the cold environment causes the rotor core body 12 to contract more rapidly than any residual thermal effects of the reinforcing ring. Therefore, during assembly, when the rotor core body 12 is returned to the chamber U, the rotor core body 12 exerts an outward pressure and prestresses the reinforcing ring 14 without creating undue stress on the stiffness. I can do it.

This means that the rotor core body 12 expands uniformly outward.
As such, the stresses created in the rotor core body 12 are not large enough to cause cracks and damage, resulting in stiffness being distributed throughout the core body.

The reinforcing ring 14 is made of a composite of graphite fibers and epoxy resin filament wrapping. In the preferred example, the graphite fibers used to form the ring 14 are wound at an angle of 0° to the underwater surface of the base of the rotor body 12. This structure induces hoop stresses in the stiffening ring that balance and counteract the outward stresses in the rotor core body 12. The rotor core body 12 and the ring 14 are held tightly together by a hollow surface 22 with an interference fit. Because of its uniform winding, the reinforcing ring 14 is made of an anisotropic material that adapts to the stresses generated when the machine assembly is rotating in a predetermined direction during the centrifugal period. A reinforcing ring 1 is used to hold the aluminum core body 12 together at speeds exceeding the
Utilizes the unidirectional stress generated in 4. One continuous cylindrical filament winding is a reinforcing ring 14.
By having this, the present invention can utilize the relative coefficients of thermal expansion I of the metal rotor core body 12 and the reinforcing ring 14 to reduce the stress generated in the rotor core. The reinforcing ring 14 serves to reinforce the strength of the rotor core body 12 without creating substantial additional stress on the rotor core body, since the rotor core body
This is to press the reinforcing ring 14 outward so that stress acts on the reinforcing ring along the intermediate plane 22 between the reinforcing ring 14 and the rotor core body.

Other alternative structures may be used to construct the reinforcement ring 14. Instead of graphite, a ring may be selected for the filament winding made of fibers of Karas or Kevlar (trade name), a striking resin manufactured by DuPont. Instead of epoxy resin, the conventionally used thermoplastic! Polymer or heat-transferable resins may be used.

FIG. 2 shows a hybrid centrifuge rotor assembled according to the method shown in FIG.
A constant angle rotor is shown. In Figure 2, the rotor with T<
It is surrounded by a reinforcing ring 24 in the shape of a truncated cone and encloses a central tapered rotor core body 20. Reinforcement ring 24
is manufactured according to the criteria described in 1) η for manufacturing the reinforcing ring 14.

The rotor core body 20 may be provided with a test tube insertion portion 26, which means that when the rotor core body 20 is immersed in a liquid bath, the contraction caused by the diameter of the tube body is caused by a plurality of water droplets. That of the surface: Along h (linear, i.e.
This is because the relationship between the diameter contraction and the coefficient of thermal expansion of the rotor core body 20 is linear and uniform along the water surface passing through the rotor core body 20. A conventional pressure or mechanical fit connects a tapered rotor core body 20 to a frusto-conical reinforcing ring 2.
If you try to incorporate it into 4, it won't turn out like this.

When manufacturing centrifuge rotors made of hybrid materials, it is important to have an interference fit. Experimental experience with time versus the amount of shrinkage in a cold environment indicates that 0.25 hours is the optimal time to immerse the metal rotor core body 12 or 20 in a liquid nitrogen bath.

In a preferred embodiment, the rotor core body 12 is made of metal.
reaches equilibrium in the nitrogen bath after 15 minutes, resulting in 0.25
Soaking for longer than this time will not result in further shrinkage. However, shrinkage equations and empirically determined relationships between shrinkage and time are useful in obtaining optimal cold soak conditions when shrinkage criteria differ from the preferred embodiment. Rotor core body 1
2 is removed from the liquid nitrogen bath and 3 to 4 hours after the reinforcing ring 14 is placed around the rotor core body 12 is required for the interference fit to be fully effective. Upon reaching room temperature, the rotor core body 12 attempts to return to its original diameter and exerts no more than 500,000 psi of pressure outwardly against the intermediate surface 22 due to the inner diameter of the reinforcing ring 14.

The interference fit described in section 117f, which creates a uniform outward stress on the reinforcing ring 14 by the rotor core body 12, meets design specifications for static and dynamic loads. A hybrid rotor designed with an isotropic core body has greater static load strength than an all-aluminum rotor--while it has superior dynamic load characteristics due to the interference fit. By having the rotor core body prestress the rings, the dynamic tangential centrifugal forces that occur during ultracentrifugation are handled, rather than traditional configurations with outer rings that create stresses in the rotor core body. A load characteristic is created that has the effect of counteracting the outward static load on the rotor core.
Hoop stresses experienced in the reinforcing ring of the present invention also include dynamic tangential forces as the ring is fixed to the roke core body during rotation. By applying the primary crushing and dynamic loading to the stiffening ring rather than the rotor core body, it is possible to reduce the load on the rotor drive bearings, as well as to equal the speeds achievable with a conventional isotropic titanium rotor. The ability of the hybrid rotor of the present invention to withstand rotational speeds of 500 mL and above can be explained by an interference fit.

A fully assembled high-capacity hybrid centrifuge rotor built in accordance with the present invention achieves lower maximum speeds than the conventional ancient IJik aluminum unitary rotor, which is equal to or greater than the conventional titanium rotor. Aluminum core rotors can safely reach upper speed limits beyond that. The hybrid structure prestresses the reinforcing ring 14, thereby ensuring that the reinforcing ring 14 is secured to the surface of the rotor body core such that high centrifugation speeds are achieved with the hybrid rotor body. The reinforcing ring 14 is
Reliably holds the rotor core body 12 in place at higher speeds than conventional limits for aluminum body rotors. Since the stress of the aluminum core body is within the specified specification and aluminum is easy to machine, the core body for striking the human body part for the 11 straight pipe rotor is manufactured as shown in FIG. This capacity of 1 iL is the capacity of a conventional 8 cavity titanium rotor! greater than 1'L.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a hybrid centrifuge rotor of the present invention, a cross-sectional view taken along the diameter of a straight tube rotor body made in accordance with the present invention. FIG. 2 is a longitudinal section taken along the diameter of a constant angle rotor manufactured as a hybrid centrifuge rotor. 12.20... Rotor core body, 14.24... Reinforcement ring, 16... Test tube cavity, 18... Drive shaft hole, 26... Test tube insertion part 26°

Claims (12)

[Claims] (1) comprising a rotor core body and a reinforcing ring made of an anisotropic material surrounding the rotor core body, wherein the reinforcing ring is configured by an interference fit between the rotor core body and the reinforcing ring; The hybrid centrifuge rotor is prestressed by (2) The hybrid centrifuge rotor according to claim (1), wherein the rotor core body is made of lightweight aluminum material. (3) The hybrid centrifuge rotor according to claim (1), wherein the reinforcing ring is a cylindrical ring around which graphite fibers and epoxy resin filaments are wound. (4) The resin is thermoplastic.
The hybrid centrifuge rotor according to item 3). (5) The resin is thermosetting.
The hybrid centrifuge rotor according to item 3). (6) The hybrid centrifuge rotor according to claim (3), wherein the fibers of the filament-wound ring are made of an organic resin material. (7) A hybrid centrifuge rotor having an isotropic core body and a filament-wrapped anisotropic reinforcement ring surrounding and prestressed by the core body, the rotor comprising: cooling the core body to shrink its diameter; fitting the ring to the core body; and preventing the core body from expanding relative to the ring and exerting pressure evenly on the ring. , bringing the core body to room temperature. (8) Cooling the core body comprises immersing the core body in a low temperature environment for an empirically derived optimum time to achieve the desired diameter contraction.
The hybrid centrifuge rotor according to item 7). (9) The anisotropic reinforcing ring surrounding the core body is comprised of a filament wound in the circumferential direction at a direction angle equal to 0 degrees from the horizontal plane of the core body, The hybrid centrifuge rotor according to item (7) or item (8). (10) The hybrid centrifuge rotor according to claim (9), wherein the filament is wound so as to intersect with the horizontal plane at an angle other than 0 degrees. (11) placing a rotor core body made of an isotropic material in a low-temperature environment and shrinking the dimensions of the rotor core body; fitting a reinforcing ring of anisotropic material therearound and bringing the rotor core body assembled into the reinforcing ring to room temperature so that the rotor core body expands against the ring to form an interference fit. A method for manufacturing a hybrid centrifuge rotor, comprising a step of returning the rotor. (12) The rotor core body is dimensionally shrunk uniformly and by a predetermined amount in the low temperature environment, and the diameter of the core body is shrunk uniformly according to an empirically obtained time vs. shrinkage diagram. The optimum time for exposing the rotor core body to the low temperature environment is selected to achieve the desired shrinkage of the rotor core body.
11) The method for manufacturing a hybrid centrifuge rotor according to item 11).