1. A pneumatic tire that includes a belt layer having a circumferential reinforcing layer and a pair of cross belts, comprising:
at least three or more circumferential main grooves having groove bottoms that are convex in the depth direction in a tread portion, wherein
in a cross-sectional view in the tire meridian direction, of the circumferential main grooves, a circumferential main groove having the circumferential reinforcing layer below the groove is a first circumferential main groove, and another circumferential main groove is a second circumferential main groove not having the circumferential reinforcing layer below the groove, and
the curvature radius RA of the groove bottom of an arbitrary first circumferential main groove and the curvature radius RB of the groove bottom of an arbitrary second circumferential main groove have the relationship RA<RB.
2. The pneumatic tire according to claim 1, wherein the curvature radius RA of the groove bottom of an arbitrary first circumferential main groove and the curvature radius RB of the groove bottom of an arbitrary second circumferential main groove have the relationship 1.10\u2266RBRA\u22661.60.
3. The pneumatic tire according to claim 1, wherein there is a plurality of second circumferential main grooves in a region bounded by the tire equatorial plane, and the curvature radius RB_out of the groove bottom of the second circumferential main groove that is in the outermost side in the tire width direction and the curvature radius RB of the groove bottom of the other second circumferential main grooves have the relationship RB<RB_out.
4. The pneumatic tire according to claim 1, wherein the belt layer has a plurality of circumferential reinforcing layers laminated on each other, and there is a plurality of first circumferential main grooves in a region bounded by the tire equatorial plane, and at least one of the first circumferential main grooves has the plurality of circumferential reinforcing layers below the groove, and
the curvature radius RA_min of the groove bottom of the first circumferential main groove having the smallest number of circumferential reinforcing layers from among all the first circumferential main grooves and the curvature radius RA of the groove bottom of the other first circumferential main grooves have the relationship RA<RA_min.
5. The pneumatic tire according to claim 1, wherein the circumferential reinforcing layer is disposed on the inner side in the tire width direction from the left and right edge portions of the cross belt with the narrower width from among the pair of cross belts, and the width W of the narrower cross belt and the distance S from the edge portion of the circumferential reinforcing layer to the edge portion of the narrower cross belt are within the range 0.03\u2266SW.
6. The pneumatic tire according to claim 1, wherein wire from which the circumferential reinforcing layer is made is steel wire, and the circumferential reinforcing layer has not fewer than 17 ends50 mm and not more than 30 ends50 mm ends.
7. The pneumatic tire according to claim 1, wherein the diameter of the wire not less than 1.2 mm and not more than 2.2 mm.
8. The pneumatic tire according claim 1, wherein the circumferential reinforcing layer is formed by winding a single steel wire in a spiral manner.
9. The pneumatic tire according to claim 1, wherein the circumferential reinforcing layer is formed by winding a plurality of wires spirally adjacent to one another.
10. The pneumatic tire according to claim 9, wherein the plurality of wires includes five or fewer wires.
11. The pneumatic tire according to claim 10, wherein a width of winding per layer of the wires when the wires are would in multiple layers is 12 mm or less.
12. The pneumatic tire according to claim 9, wherein the plurality of wires are would while inclined with respect to the tire circumferential direction in the range of \xb15 degrees.
13. The pneumatic tire according to claim 9, wherein a wire diameter is in the range of not less than 1.2 mm and not more than 2.2 mm.
14. The pneumatic tire according to claim 13, wherein the wire diameter is measured as a diameter of a circle circumscribing the plurality of wires.
15. The pneumatic tire according to claim 1, wherein elongation of belt cords of the circumferential reinforcing layer when subjected to a tensile load of 150 N to 200 N is not less than 2.0% and not more than 3.5%.
16. The pneumatic tire according to claim 1, wherein:
the curvature radius RA of the groove bottom of an arbitrary first circumferential main groove and the curvature radius RB of the groove bottom of an arbitrary second circumferential main groove have the relationship 1.10\u2266RBRA\u22661.60; and
there is a plurality of second circumferential main grooves in a region bounded by the tire equatorial plane, and the curvature radius RB_out of the groove bottom of the second circumferential main groove that is in the outermost side in the tire width direction and the curvature radius RB of the groove bottom of the other second circumferential main grooves have the relationship RB<RB_out.
17. The pneumatic tire according to claim 1, wherein:
the belt layer has a plurality of circumferential reinforcing layers laminated on each other, and there is a plurality of first circumferential main grooves in a region bounded by the tire equatorial plane, and at least one of the first circumferential main grooves has the plurality of circumferential reinforcing layers below the groove, and the curvature radius RA_min of the groove bottom of the first circumferential main groove having the smallest number of circumferential reinforcing layers from among all the first circumferential main grooves and the curvature radius RA of the groove bottom of the other first circumferential main grooves have the relationship RA<RA_min; and
the circumferential reinforcing layer is disposed on the inner side in the tire width direction from the left and right edge portions of the cross belt with the narrower width from among the pair of cross belts, and the width W of the narrower cross belt and the distance S from the edge portion of the circumferential reinforcing layer to the edge portion of the narrower cross belt are within the range 0.03\u2266SW.
18. The pneumatic tire according to claim 1, wherein:
wire from which the circumferential reinforcing layer is made is steel wire, and the circumferential reinforcing layer has not fewer than 17 ends50 mm and not more than 30 ends50 mm ends; and
the diameter of the wire not less than 1.2 mm and not more than 2.2 mm.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A sprue for a lost foam casting process, comprising:
a longitudinally extending first member made of evaporative material, said first member having an upper receiving end for receiving molten metal, and a lower outlet end;
a longitudinally extending second member made of evaporative material, said second member having a lower inlet end;
a connection member made of evaporative material and laterally connected between said outlet end of said first member and said inlet end of said second member,
said second member being attachable through at least one laterally extending in-gate to a pattern of an object to be cast from said molten metal, said pattern being made of evaporative material,
whereby said molten metal is directed to flow from said upper receiving end of said first member of said sprue longitudinally downwardly through said first member of said sprue to said lower outlet end of said first member of said sprue then laterally through said connection member of said sprue to said lower inlet end of said second member of said sprue then longitudinally upwardly through said second member of said sprue to said in-gate then laterally through said in-gate to said pattern of said object to be cast.
2. The sprue accordingly to claim 1 wherein said evaporative material yields buoyant effluents upon vaporization thereof by said molten metal, said effluents rising upwardly against the downward flow of said molten metal through said first member of said sprue, said effluents rising upwardly with the upward flow of said molten metal through said second member of said sprue, and wherein said second member of said sprue extends longitudinally upwardly beyond said in-gate to an upper section permitting congregation of said effluents therein, such that said effluents may bypass said in-gate and instead flow to said upper section of said second member of said sprue, whereby to reduce effluent flow through said in-gate, to minimize defective cast objects otherwise caused by effluents mixed with said molten metal in said cast object.
3. The sprue according to claim 1 wherein said molten metal flows through said in-gate and into said pattern of said object to be cast only after said molten metal has flowed downwardly then upwardly through said sprue, namely downwardly through said first member of said sprue then upwardly through said second member of said sprue, prior to flowing laterally into said pattern through said in-gate.
4. The sprue according to claim 1 comprising a plurality of said in-gates longitudinally spaced along said second member of said sprue, wherein said molten metal sequentially reaches said in-gates in an upward flow of said molten metal from one in-gate to another in-gate thereabove.
5. The sprue according to claim 1 comprising:
a longitudinally extending third member made of evaporative material, said third member having a lower inlet end;
a second connection member made of evaporative material and laterally connected between said outlet end of said first member and said inlet end of said third member,
said third member being attachable through at least one laterally extending second in-gate to a second pattern of a second object to be cast from said molten metal, said second pattern being made of evaporative material,
whereby said molten metal is directed to flow from said upper receiving end of said first member of said sprue longitudinally downwardly through said first member of said sprue to said lower outlet end of said first member of said sprue then laterally through said first mentioned connection member of said sprue to said lower inlet end of said second member of said sprue then longitudinally upwardly through said second member of said sprue to said first mentioned in-gate then laterally through said first in-gate to said first mentioned pattern of said first mentioned object to be cast, and whereby said molten metal is also directed to flow from said upper receiving end of said first member of said sprue longitudinally downwardly through said first member of said sprue to said lower outlet end of said first member of said sprue then laterally through said second connection member of said sprue to said lower inlet end of said third member of said sprue then longitudinally upwardly through said third member of said sprue to said second in-gate then laterally through said second in-gate to said second pattern of said second object to be cast.