Composite material centrifuge rotor

• US 4,781,669 A
• Filed: 10/09/1987
• Issued: 11/01/1988
• Est. Priority Date: 06/05/1987
• Status: Expired due to Fees

• Current Assignee: Beckman Instruments, Inc. (Danaher Corporation)
• Original Assignee: Beckman Instruments, Inc. (Danaher Corporation)
• Inventors: Piramoon, Alireza M.
• Primary Examiner(s): Simone, Timothy F.
• Application Number:
  US07/107,187
• Time in Patent Office: 389 Days
• Field of Search: 494/81, 494/16, 494/37, 494/85, 494/43, 494/17, 156/169, 156/172, 156/173, 156/175
• US Class Current: 494/16
• CPC Class Codes: B04B 7/085 fibre- or metal-reinforced
• CPC Class Codes: B04B 9/14 Balancing rotary bowls balancing per se G01M; Schrappers
• CPC Class Codes: B29C 53/66 with axially movable winding feed member , e.g. lathe type winding

Abstract

A composite material centrifuge rotor and process of construction of the rotor is disclosed. A rotor having high stiffness of fibers, preferably carbon, bound together with resin is disclosed. The rotor includes a top disk, a bottom disk and a spacer belt spacing the two disks apart to form a rotor assembly. The top and bottom disks are fabricated by overlying multiple layers of tape, the tape being made from longitudinally extending and parallel fibers held together with resin. The tapes are stacked in multiple layers normal to the spin axis of the rotor so as to lie within the plane of the centrifugal force exerted by the rotor. Successive layers of tape are oriented so as to vary the longitudinal direction of the fiber with respect to a preselected radius vector from the spin axis of the rotor. When the tape is compiled in multiple layers to a thickness of the top and bottom disk, the tape is compressed between two metal plates and cured at a temperature well above the expected autoclave temperature of sterilization of the rotor. Thereafter, a spacer belt consisting of a spirally wound resin impregnated and cured fiber is placed to space the top and bottom disks apart. Thereafter, the entire assembly is wound by a peripheral belt with resin impregnated high stiffness fiber. This fiber is cured and shrinks during curing to exert hoop tension around the periphery of the rotor assembly. This hoop tension in turn radially prestresses the rotor equal and opposite to the radial tension forces of centrifugal force when the rotor is in use.

A hub having a mount only to the lower plate is disclosed which effective cantilevers the rotor on the centrifuge spindle. A system of balancing inserts and interchangeable inserted buckets enables final balance of the rotor for the centrifuging of samples.

Claims

1. A composite rotor construction comprising in combination a top disk and a bottom disk, each said disk fabricated from laminated layers with longitudinally extending fibers for reinforcing, said fibers bound together with resins;

said laminated layers having a sequentially repeating pattern of radial directions having different angular orientations with respect to a selected radii extending normal to the spin axis of said rotor, each said laminated layer being normal to the spin axis of said rotor;

a spacer ring comprising a wound fiber hoop sandwiched between said top disk and said bottom disk to form a rotor assembly;

a radial fiber hoop cured to shrink under tension over the periphery of said rotor assembly and overlie the outside surface of said top disk, said bottom disk and said spacer ring therebetween whereby said rotor assembly at said top disk, bottom disk and spacer ring are radially compressed with respect to the spin axis of said rotor equal and opposite to the dynamic forces of radial tension on said rotor; and

said bottom disk defining a hub aperture;

a hub placed within said hub aperture in said bottom disk, said hub adapted for fitting into said aperture under a shrink fit.

2. The invention of claim 1 and including a nut fastened to the top surface of said bottom disk at the inside of said rotor for clamping said disk between said nut and hub;

said nut and hubs defining complementary mating threads for securing said nut to said hub with said disk captured therebetween.

3. The invention of claim 2 and wherein said hub protrudes through said disk at threads for permitting said nut to fit to said bottom disk on outside threads.

4. The invention of claim 1 and wherein said nut includes inside threads interior of said aperture for engaging said threads on said hub.

5. The invention of claim 1 and including a flange attached to said hub, said flange including a plurality of bolts extending from said flange upwardly through said disk.

6. A process of rotor construction comprising the steps of:

providing a top disk and a bottom disk, each said disk fabricated from laminated layers with longitudinally extending fibers for reinforcing;

boring a hole centrally of said bottom disk;

providing a hub, said hub having a flange for engaging the bottom of said bottom disk on one side and having threads extending through said disk towards the other side of said disk;

shrink fitting said hub to said bottom disk at a central aperture;

providing a nut for securing said hub to said bottom disk;

securing said nut to said bottom disk;

providing a spacer ring;

sandwiching said spacer ring between said top disk and said bottom disk to form said rotor assembly and enclose said nut;

winding a radial fiber loop under tension over the periphery of said rotor assembly and over the outside surface of said top disk whereby said rotor assembly of said top disk, bottom disk and spacer ring are radially compressed;

centering said rotor with respect to said wound radial fiber hoop; and

,

boring a finished aperture in said hub for a spindle with respect to the centering of said rotor around said wound radial fiber hoop.

7. A composite rotor construction having interchangeable sample buckets comprising in combination a top disk and a bottom disk, each said disk fabricated from laminated layer with longitudinal extending fibers for reinforcing, said fibers bound with resin;

said top disk and bottom disk including peripheral registered apertures for receiving sample buckets therein;

inserts for placement within said sample bucket, said inserts having an outside diameter for shrink fitting to said rotor at the top and bottom of said peripheral registered apertures, said inserts having an inside diameter for precisely receiving sample buckets;

a flange on said inserts exposed to the outside of one of said disks for permitting material to be removed to enable balancing of said rotor;

sample buckets for placement in said insert, said sample buckets having an outside diameter conforming to the inside diameter of said inserts whereby said inserts can withstand dynamic loading forces placed on said rotor.

8. The invention of claim 7 and wherein said sample buckets combine an annulus at the upper end thereof, said annulus enabling the flange of said insert to be received under said annulus whereby said sample bucket fits precisely within said rotor at the same depth with respect to said rotor.

9. A process of balancing a composite rotor comprising the steps of

providing a top disk and a bottom disk, each said disk fabricated from laminated layers with longitudinally extending fibers for reinforcing;

configuring registered holes in said top disk and bottom disk each said registered hole for receiving a sample bucket;

providing inserts for insertion in said registered holes in said top and bottom disks, said inserts having a flange for protruding upwardly from said bottom, upwardly from said disks;

inserting said inserts at said holes of said disks;

removing material from said flanges in said inserts to balance said rotor;

providing buckets having an outside dimension equivalent to the inside dimension of said inserts; and

inserting buckets within said inserts whereby said buckets maintain said inserts from collapse during dynamic loading of said rotor and said centrifuge.

10. The invention of claim 9 and wherein said buckets are provided with an annulus to receive the flange of said insert whereby said buckets have a constant depth of insertion around said rotor.