Stud pin and studded tire
A stud pin includes a tip, a body portion that supports the tip, and a lower flange connected to the body portion at an end on an opposite side to the end surface. A profile shape of the lower flange and a body profile shape of the body portion are anisotropic shape. The flange profile shape includes four or more first flange protrusion portions projecting toward the longitudinal direction and two second flange protrusion portions projecting toward the lateral direction. The body profile shape includes four or more first body protrusion portions projecting toward the lateral direction and two second body protrusion portions projecting toward the longitudinal direction.
1. A stud pin installable in a tire, comprising:
a tip comprising an end surface that comes into contact with a road surface;
a body portion that supports the tip so that the tip projects from an end surface on one side of the body portion; and
a lower flange connected to an end of the body portion on an opposite side to the end surface;
a flange profile shape of the lower flange as viewed from an arrangement direction of the tip, the body portion, and the lower flange being an anisotropic shape in which, of imaginary rectangles circumscribing the flange profile shape, a first smallest rectangle with a shortest side of its four sides being smallest and/or a second smallest rectangle with a longest side of its four sides being smallest comprise short sides and long sides of different lengths;
a body profile shape of the body portion as viewed from the arrangement direction having an anisotropic shape in which a length of the body profile shape in a longitudinal direction parallel with the long sides is different from a length of the body profile shape in a lateral direction parallel with the short sides;
the flange profile shape comprising
four or more first flange protrusion portions projecting toward the longitudinal direction,
two second flange protrusion portions projecting toward the lateral direction, and
two first flange recess portions curved toward a centroid of the flange profile shape and disposed between the first flange protrusion portions; and
the body profile shape comprising
four or more first body protrusion portions projecting toward the lateral direction, and
two second body protrusion portions projecting toward the longitudinal direction, the second body protrusion portions disposed facing the first flange recess portions at a position on a body profile shape centroid side of the first flange recess portions in a plan view of the lower flange and the body portion from the arrangement direction, wherein
longitudinally most protruding tip portions of the first flange protrusion portions are disposed further outward in the lateral direction from the centroid of the flange profile shape than portions of the tip positioned furthest outward in the lateral direction from the centroid of the flange profile shape.
2. The stud pin according to claim 1 , wherein
the first flange protrusion portions are constituted by two pairs of thereof; and
the flange profile shape comprises two first flange recess portions and four second flange recess portions, the four second flange recess portions being curved toward the centroid, disposed between each of the second flange protrusion portions and one of the first flange protrusion portions, and smoothly connect to one of the first flange protrusion portions.
3. The stud pin according to claim 2 , wherein a recess depth of the first flange recess portions is equal to or greater than a recess depth of the second flange recess portions.
4. The stud pin according to claim 3 , wherein
the two second flange protrusion portions comprise two linear portions parallel with the longitudinal direction; and
the linear portions are portions projecting the most in the lateral direction.
5. The stud pin according to claim 4 , wherein
the first body protrusion portions are constituted by two pairs of first body protrusion portions;
the body profile shape comprises two first body recess portions curved toward a centroid of the body profile shape and disposed between each of the pairs of the first body protrusion portions; and
the first body recess portions are disposed facing the linear portions at a position on a body profile shape centroid side of the linear portions in a plan view of the lower flange and the body portion from the arrangement direction.
6. A studded tire installed with a stud pin, comprising:
a tread portion installed with the stud pin described in claim 5 with the longitudinal direction or the lateral direction facing a tire circumferential direction.
7. The stud pin according to claim 3 , wherein
the second body protrusion portions are curved away from the centroid of the body profile shape in a plan view of the lower flange and the body portion from the arrangement direction; and
a radius of curvature of the second body protrusion portions at a position where the second body protrusion portions are closest to the first flange recess portions is greater than a radius of curvature of the first flange recess portions at a position where the first flange recess portion is closest to the second body protrusion portions.
8. The stud pin according to claim 2 , wherein
the second body protrusion portions are curved away from the centroid of the body profile shape in a plan view of the lower flange and the body portion from the arrangement direction; and
a radius of curvature of the second body protrusion portions at a position where the second body protrusion portions are closest to the first flange recess portions is greater than a radius of curvature of the first flange recess portions at a position where the first flange recess portion is closest to the second body protrusion portions.
9. The stud pin according to claim 1 , wherein
the two second flange protrusion portions comprise two linear portions parallel with the longitudinal direction; and
the linear portions are portions projecting the most in the lateral direction.
10. The stud pin according to claim 9 , wherein
the first body protrusion portions are constituted by two pairs of thereof;
the body profile shape comprises two first body recess portions curved toward a centroid of the body profile shape and disposed between each of the pairs of the first body protrusion portions; and
the first body recess portions are disposed facing the linear portions at a position on a body profile shape centroid side of the linear portions in a plan view of the lower flange and the body portion from the arrangement direction.
11. A studded tire installed with a stud pin, comprising:
a tread portion installed with a stud pin, the stud pin comprising:
a tip comprising an end surface that comes into contact with a road surface;
a body portion that supports the tip so that the tip projects from an end surface on one side of the body portion; and
a lower flange connected to an end of the body portion on an opposite side to the end surface;
a flange profile shape of the lower flange as viewed from an arrangement direction of the tip, the body portion, and the lower flange being an anisotropic shape in which, of imaginary rectangles circumscribing the flange profile shape, a first smallest rectangle with a shortest side of its four sides being smallest and/or a second smallest rectangle with a longest side of its four sides being smallest comprise short sides and long sides of different lengths;
a body profile shape of the body portion as viewed from the arrangement direction having an anisotropic shape in which a length of the body profile shape in a longitudinal direction parallel with the long sides is different from a length of the body profile shape in a lateral direction parallel with the short sides;
the flange profile shape comprising
four or more first flange protrusion portions projecting toward the longitudinal direction,
two second flange protrusion portions projecting toward the lateral direction, and
two first flange recess portions curved toward a centroid of the flange profile shape and disposed between the first flange protrusion portions; and
the body profile shape comprising
four or more first body protrusion portions projecting toward the lateral direction, and
two second body protrusion portions projecting toward the longitudinal direction, the two second body protrusion portions disposed facing the first flange recess portions at a position on a body profile shape centroid side of the first flange recess portions in a plan view of the lower flange and the body portion from the arrangement direction, wherein
longitudinally most protruding tip portions of the first flange protrusion portions are disposed further outward in the lateral direction from the centroid of the flange profile shape than portions of the tip positioned furthest outward in the lateral direction from the centroid of the flange profile shape,
the stud pin being installed with the longitudinal direction or the lateral direction facing a tire circumferential direction.