Cast tire and method of manufacture

• US 4,305,446 A
• Filed: 12/15/1980
• Issued: 12/15/1981
• Est. Priority Date: 11/30/1977
• Status: Expired due to Fees

• Current Assignee: Goodyear Tire & Rubber Company
• Original Assignee: Goodyear Tire & Rubber Company
• Inventors: Brown, Jack E. Jr., Logan, Brian M., Trinko, Michael J.
• Primary Examiner(s): Ball, Michael W.
• Application Number:
  US06/216,697
• Time in Patent Office: 365 Days
• Field of Search: 152/330 R, 152/330 RF, 152/374, 152/357 A, 152/354 R, 152/353 AC, 152/352 R, 152/352 A, 152/151, 152/361 R, 152/343, 156/110 CL, 156/125, 425/49, 425/50, 264/326, 264/328.3
• US Class Current: 152/452
• CPC Class Codes: B29D 30/06 Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
• CPC Class Codes: B29D 30/0661 Rigid cores therefor, e.g. annular or substantially toroidal cores cores for building tyres B29D30/12; drums for building tyres B29D30/24
• CPC Class Codes: B60C 13/00 Tyre sidewalls; Protecting, decorating, marking, or the like, thereof B60C17/08 takes precedence; tyre shoulders B60C11/01; removable tyre sidewall trim rings B60B7/01
• CPC Class Codes: B60C 13/004 of the internal side of the tyre
• CPC Class Codes: B60C 3/04 characterised by the relative dimensions of the section, e.g. low profile B60C3/06 takes precedence
• CPC Class Codes: Y10T 152/10828 Chafer or sealing strips

Abstract

An annular hollow tire with an inner surface having a generally positive radius of curvature and at least one circumferentially extending rib portion on the inner surface with a negative radius of curvature located at an area of the tire subject to high stresses to mitigate the stress concentrations in that area of the tire. The method of making the tire includes the steps of providing a tire mold with a core having a selected circumferentially extending portion on the outer surface with a negative radius of curvature for forming the rib portion, filling the space between the core and mold surface with an elastomeric precursor, heating to set the precursor and form the tire and removing the tire from the mold and the core from the tire.

Claims

1. A cast pneumatic tire comprising a tread portion, a pair of circumferentially extending sidewalls with outer peripheral portions connected to said tread portion and spaced apart inner peripheral portions which are connected to bead portions respectively each containing an inextensible bead ring, said tread portion further provided with a circumferentially extending reinforcing belt structure having a pair of circumferential edges spaced from either side of said midcircumferential centerplane of the tire a first distance, each of said sidewalls consisting of an elastomeric material, an outer surface, an inner surface extending between said inner peripheral portions, a first pair of circumferentially extending rib portions, one located near each of said circumferential edges of said reinforcing belt structure on the inner surface and the centroid of the cross-sectional area of each of said rib portions being spaced from the midcircumferential plane a second distance measured axially of said tire from the midcircumferential centerplane of said tire and the difference between said first distance and second distance being equal to or less than one-half the width of either of said first rib portions, a circumferentially extending unfolded reinforcing strip with parallel edges is located in each of the bead portions of said tire, a second pair of rib portions, one being located adjacent said reinforcing strip on the inner surface and having a width greater than the width of said strip so that each of said second rib portions overlap the edges of said reinforcing strip.

2. A tire according to claim 1 wherein said tire has a wall thickness at the midcircumferential centerplane greater than the maximum depth of either of said first pair of circumferentially extending rib portions.

3. A tire according to claim 2 wherein said maximum depth of each of said rib portions of said first pair of rib portions is from 20 to 80% of said wall thickness at the midcircumferential plane of the tire.

4. A tire according to claim 1 wherein said tire has a half section width measured from the midcircumferential centerplane of the tire to the axially outermost portion of said tire, the said outer surface, and the width of each of said rib portions of said first pair of circumferentially extending rib portions is from 10 to 85% of said sectional width of said tire.

5. A tire according to claim 4 wherein the centroid of the cross-sectional area of each of said rib portions of said first pair of circumferentially extending rib portions is spaced respectively from the midcircumferential centerplane of said tire a distance from 20 to 85% of said half section of said tire.

6. A tire according to claim 5 wherein said tire has a wall thickness at the midcircumferential centerplane which is greater than the maximum depth of either of said rib portions of said first pair of circumferentially extending rib portions.

7. A tire according to claim 6 wherein a second circumferentially extending reinforcing belt is located in said tread portion and has a pair of circumferential edges spaced from either side said midcircumferential centerplane of the tire a third distance, each of said sidewalls are further provided with a third circumferentially extending rib portion on said inner surface of said tire with a negative radius of curvature said third rib portions being located near said second rib portions and the centroid cross-sectional area of each of said third rib portions being spaced from said midcircumferential centerplane a fourth distance measured axially of said tire and the difference between said third and fourth distances being equal to or less than one-half of the width of either of said third rib portions.

8. A tire according to claim 1 wherein said first rib portion and said third rib portion are spaced apart.

9. A tire according to claim 1 wherein each of said first rib portions overlap the edge of said reinforcing strip which it is associated with by a distance less than the width of said reinforcing strip.

10. A tire according to claim 1 wherein each of said sidewalls of said tire has a fourth circumferential rib portion located in said bead area of said tire, said second rib portion and said fourth rib portion being located respectively over at least one edge of said reinforcing strip.

11. A method of making a cast pneumatic tire having a tread portion, a pair of circumferentially extending sidewalls with outer peripheral portions connected to said tread portion and spaced apart inner peripheral portions, said sidewalls consisting of an elastomeric material, said tread portion being provided with a circumferentially extending reinforcing belt structure having a pair of circumferential edges spaced from either side of said midcircumferential centerplane of the tire a first distance, said inner peripheral portion each being provided with a circumferentially ending reinforcing strip with parallel edges, comprising the steps of:

providing an annular rigid tire mold having a mold cavity with an inner molding surface for forming the outer surface of said tire;

providing an annular rigid core inside said mold having an outer molding surface spaced from said inner molding surface;

providing said outer molding surface with a general positive radius of curvature for forming the inner surface of the tire;

providing a pair of circumferentially extending portions on said outer surface of said core with a negative radius of curvature for forming areas of increase thickness of said tire in each of said sidewalls which are subjected to high stresses, casting said tire by filling the space between said outer and inner molding surface with an elastomeric precursor, setting the precursor to form in each of said sidewalls of said tire with a first circumferentially extending rib and a second circumferentially extending rib, said first circumferentially extending rib being located near said circumferential edge of said reinforcing belt structure and the centroid of the cross-sectional area of said rib being spaced from the midcircumferential plane a second distance measured axially of said tire from the midcircumferential centerplane of said tire and a difference between said first distance and second distance being equal to or less than one-half the width of said first rib portion, said second circumferential rib portion located adjacent said reinforcing strip and having a width greater than the width of said reinforcing strip so that said second rib portion overlaps the edges of said reinforcing strip;

removing said tire from said mold cavity.

12. The method according to claim 11 wherein said elastomeric material is polyurethane formed by casting a liquid polyurethane.

13. The method according to claim 11 wherein said elastomeric material is polyurethane and said tire is cast by filling said space between said outer and inner molding surface with said elastomeric precursor of liquid polyurethane reaction mixture and curing said tire by heating.

14. The method according to claim 13 including providing said outer and inner molding surface in spaced apart position wherein the distance between said surface at the centerline of said mold is greater than the depth of said circumferentially extending portion of said outer surface of said core with said negative radius of curvature so that when the tire is cast the wall thickness at the centerline will be greater than the maximum depth of said first rib.

15. The method according to claim 14 further providing a depth for said first circumferentially extending rib being from 20% to 80% of the distance between said outer and inner molding surface at the centerline.