Needle bearing

Patent metadata

Field	Value
Publication number	US-10302127-B2
Application number	US-201615565184-A
Country	US
Kind code	B2
Filing date	Apr 26, 2016
Priority date	Apr 28, 2015
Publication date	May 28, 2019
Grant date	May 28, 2019

Abstract

The present invention relates to a non-magnetic needle bearing for use in a rotational machine such as, for example, an MRI. The needle bearing may include needles, a cylindrical retainer holding the needles at a predetermined pitch, an outer ring outside of the retainer, and an inner ring inside the retainer. All of the aforementioned may be made of a non-thermoplastic polyimide resin.

First claim

What is claimed is:

1. A needle bearing comprising needles, a cylindrical retainer holding the needles at a predetermined pitch, an outer ring disposed outside the retainer and an inner ring disposed inside the retainer, wherein the outer ring, the inner ring and the needles are made of a first non-thermoplastic polyimide resin comprising a repeating unit represented by the following formula:

wherein R comprises p-phenylene diamine (PPD) units and m-phenylene diamine (MPD) units;
and the retainer is made of a second non-thermoplastic polyimide resin comprising a repeating unit represented by the following formula:

2. The needle bearing of claim 1 , wherein the needle bearing comprises no ceramic or metal.

3. The needle bearing of claim 1 , wherein the second non-thermoplastic polyimide resin further comprises filler.

4. The needle bearing of claim 1 , wherein tensile strength of the first non-thermoplastic polyimide resin is from about 80 to about 250 MPa at 23° C., and the tensile strength of the second non-thermoplastic polyimide resin is from about 45 to about 100 MPa at 23° C.

5. The needle bearing of claim 1 , wherein coefficient of friction (COF) of the first non-thermoplastic polyimide resin is from about 0.07 to about 0.6 at PV=3.4 MPa·m/sec and coefficient of friction (COF) of the second non-thermoplastic polyimide resin is from about 0.01 to about 0.4 at PV=3.4 MPa·m/sec.

6. The needle bearing of claim 1 , wherein flexural strength of the first non-thermoplastic polyimide resin is from about 150 to about 350 MPa at 23° C., and flexural strength of the second non-thermoplastic polyimide resin is from about 60 to about 180 MPa at 23° C.

7. The needle bearing of claim 1 , wherein flexural modulus of the first non-thermoplastic polyimide resin is from about 4500 to about 6900 MPa at 23° C., and flexural modulus of the second non-thermoplastic polyimide resin is from about 2500 to about 4600 MPa at 23° C.

8. A rotational machine comprising at least one needle bearing of claim 1 .

9. The rotational machine of claim 8 , wherein the rotational machine is a magnetic resonance imaging (MRI).

10. The needle bearing of claim 1 , wherein R comprises greater than about 60 to about 85 mole % (PPD) units and about 15 to about 40 mole % m-phenylene diamine (MPD) units.

Assignees

• Du Pont

Inventors

• Fukazu Isao
• Sekiguchi Satoru

Classifications

• F16C33/34

  Rollers; Needles · CPC title

• F16C33/4676

  of the stays separating adjacent cage pockets, e.g. guide means for the bearing-surface of the rollers · CPC title

• C08G73/1067

  Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound · CPC title

• F16C2316/10

  in medical appliances, e.g. in diagnosis, dentistry, instruments, prostheses, medical imaging appliances · CPC title

• C08G73/1042

  Copolyimides derived from at least two different tetracarboxylic compounds or two different diamino compounds · CPC title