Self lubricating linear motion guided screw assembly

1. A cartridge assembly for use in conjunction with a linear motion guided screw assembly, the cartridge assembly comprising:

a) a cylindrical housing having an axial bore, at least a portion of said bore being defined by a threaded surface configured to engage a screw shaft;

b) at least one bearing disposed in the axial bore of the housing;

c) at least one retainer ring disposed in the axial bore of the housing; and,

d) a cylindrical lubricant block disposed in the axial bore of the housing, said lubricant block being fabricated from a microporous polymer which is impregnated with a lubricant oil,

and shaped as a ring having a smooth inner surface disposed to contact only a major diameter of the guide screw.

2. The cartridge assembly of claim 1 wherein the lubricant block comprises adjacent first and second portions which are separable from each other, wherein said first and second portions, when joined at an interface, define an axial channel.

3. The cartridge assembly of claim 1 wherein the lubricant block comprises a circumferential channel.

4. The cartridge assembly of claim 3 including an O-ring or circular spring member disposed within the circumferential channel of the lubricant block.

5. The cartridge assembly of claim 1 wherein the lubricant block includes first and second opposite ends, each end including a recess defined by an axially-extending circumferential ridge and an annular surface opening towards the axial direction.

6. The cartridge assembly of claim 5 further including first and second belleville washers, each belleville washer being configured to be seated in a respective end recess of the lubricant block.

7. The cartridge assembly of claim 1 wherein the lubricant block is fabricated from high density polyethylene or polymethylpentene.

8. The cartridge assembly of claim 1 wherein the lubricant oil is selected from mineral oil, vegetable oil, animal oil hydrogenated polyolefins, polyesters, silicones and fluorocarbons.

9. A lubricant block fabricated from a microporous polymer which is impregnated with a lubricant oil, wherein the lubricant block comprises

adjacent first and second portions which are separable from each other, wherein said first and second portions, when joined at an interface, define an axial channel,

a circumferential channel configured to receive an O-ring or circular spring,

wherein the lubricant block includes first and second opposite ends, each end including a recess defined by a circumferential ridge and an annular surface.

10. The lubricant block of claim 9 wherein the lubricant block is fabricated from high density polyethylene or polymethylpentene, and the lubricant oil is selected from mineral oil, vegetable oil, animal oil hydrogenated polyolefins, polyesters, silicones and fluorocarbons.

11. A linear motion guided screw assembly comprising:

a) at least a first end support;

b) a screw shaft having a thread form and defining a longitudinal direction and rotatably mounted at one end to the first end support, a thread form of the screw being arranged so as to support both axial and radial loads,

c) a guidance means mounted to said end support and oriented parallel to the screw shaft;

d) a follower assembly physically associated to the screw shaft and, associated therewith, an anti-rotation means in translatable contact with the guidance means and movable in a longitudinal direction along said guidance means; and

e) a cartridge assembly including

i. a cylindrical housing having an axial bore, at least a portion of said bore being defined by a threaded surface configured to engage a screw shaft;

ii. at least one bearing disposed in the axial bore of the housing;

iii. at least one retainer ring disposed in the axial bore of the housing; and,

iv. a cylindrical lubricant block disposed in the axial bore of the housing, said lubricant block being fabricated from a microporous polymer which is impregnated with a lubricant oil,

and shaped as a ring having a smooth inner surface disposed to contact only a major diameter of the guide screw.

12. The screw assembly of claim 11 further including a second end support to which the screw shaft is rotatably mounted.

13. The screw assembly of claim 11 wherein the screw shaft is coated to improve lubricity, wear resistance, corrosion resistance, or load capacity.

14. The screw assembly of claim 11 wherein the guidance means is a linear member having a circular or polygonal cross section and the anti rotation means comprises a bearing disposed around the linear member.

15. The screw assembly of claim 11 wherein the lubricant block comprises adjacent first and second portions which are separable from each other, wherein said first and second portions, when joined at an interface, define an axial channel.

16. The screw assembly of claim 11 wherein the lubricant block comprises a circumferential channel.

17. The screw assembly of claim 16 wherein the cartridge assembly includes an O-ring or circular spring member disposed within the circumferential channel of the lubricant block.

18. The screw assembly of claim 11 wherein the lubricant block includes first and second opposite ends, each end including a recess defined by an axially-extending circumferential ridge and an annular surface opening towards the axial direction.

19. The screw assembly of claim 18 wherein the cartridge assembly further includes first and second belleville washers, each belleville washer being configured to be seated in a respective end recess of the lubricant block.

20. The screw assembly of claim 11 wherein the lubricant block is fabricated from high density polyethylene or polymethylpentene and the lubricant oil is selected from mineral oil, vegetable oil, animal oil hydrogenated polyolefins, polyesters, silicones and fluorocarbons.