Stay for headrest

1. A stay for headrest, the stay comprising:

a metallic hollow stay body formed as a letter-“U” shape including a base and paired legs extending respectively from opposite ends of the base; and

an end installation body formed of a polymeric material, and including a solid portion arranged inside a hollow interior in a leading end portion of the paired legs, and a spherical portion protruding from the leading end portion of the paired legs, wherein

the leading end portion of the paired legs includes a radially-reduced section reduced radially toward each of central axial lines of the paired legs in both of an inner peripheral face and an outer peripheral face thereof,

the outer peripheral face of the radially-reduced section forms part of a hemispherical shape,

the spherical portion of the end installation body is formed continually from an end in the outer peripheral face of the radially-reduced section, and forms a remaining other part of the hemispherical shape,

the radially-reduced section and the spherical portion form the hemispherical shape, and

the solid portion is locked to the inner peripheral face of the radially-reduced portion in a direction of the central axial lines.

2. The stay for headrest according to claim 1 , wherein the solid portion is filled over an entire length of the paired legs.

3. The stay for headrest according to claim 1 , wherein the end installation body is integrated into the stay body.

4. The stay for headrest according to claim 1 , wherein the end installation body is fixed in such a state as being fit into the paired legs.

5. A stay for headrest, the stay comprising:

a metallic hollow stay body formed as a letter-“U” shape including a base and paired legs extending respectively from opposite ends of the base;

an end installation body formed of a polymeric material, and including a solid portion arranged inside a hollow interior in the paired legs, and a spherical portion formed integrally with the solid portion and protruding from a leading end portion of the paired legs; and

an outer installation body formed of a polymeric material, and fixed onto an outer face of the stay body, wherein

each of the paired legs includes a bore formed to penetrate from an outer face thereof to an inner face thereof, and

the outer installation body not only connects the paired legs with one another, but is also formed integrally with the solid portion by way of an interior in the bores.

6. The stay for headrest according to claim 5 , wherein the outer installation body and the end installation body are formed of an identical polymeric material.

7. The stay for headrest according to claim 5 , wherein the outer installation body is a head protection plate located to face toward any one of front and rear directions of the head rest.

8. A stay for headrest, the stay comprising:

a metallic hollow stay body formed as a letter-“U” shape including a base and paired legs extending respectively from opposite ends of the base;

an end installation body formed of a polymeric material, and including a solid portion arranged inside a hollow interior in the paired legs, and a spherical portion formed integrally with the solid portion and protruding from a leading end portion of the paired legs; and

an outer installation body formed of a polymeric material, and fixed onto an outer face of the stay body, wherein

at least one of the paired legs includes a first bore formed to penetrate from an outer face thereof to an inner face thereof,

the base includes a second bore formed to penetrate from an outer face thereof to an inner face thereof, and

the outer installation body not only connects at least one of the paired legs with the base, but is also formed integrally with the solid portion by way of an interior in the first bore and by way of an interior in the second bore.

9. The stay for headrest according to claim 1 , wherein the end installation body is arranged in such a state as being bonded onto the hollow interior in the leading end portion of at least one of the paired legs among the stay body.

10. The stay for headrest according to claim 1 , wherein the end installation body is colored in any colors in compliance with types of the stay for headrest.

11. The stay for headrest according to claim 1 , wherein the end installation body includes the spherical portion integrated with the leading end portion of the paired legs in such a state that part of the spherical portion is bonded onto an end face of the leading end portion.

12. The stay for headrest according to claim 1 , wherein:

the solid end portion is not only arranged inside the hollow interior in the paired legs alone, but also is formed to have a diameter that is larger than that of an opening in the leading end portion of the paired legs, and

the solid portion is provided with a constricted configuration over an entire circumference of an outer peripheral surface thereof at a boundary between the solid portion and the spherical portion.