Patent attributes
A nut press-fit portion (8) includes a bottom surface (12), inner peripheral wall surfaces (14), press-fit ribs (10), and contact parts (11). The bottom surface (12) is opposing to a press-fit direction. The inner peripheral wall surfaces (14) are generally parallel to the press-fit direction. The press-fit ribs (10) are protruded from the inner peripheral wall surfaces (14) and elongated along the press-fit direction so as to contact the peripheral surfaces of a press-fitted nut (7). The contact parts (11) are disposed above the bottom surface (12) so as to contact the press-fitted nut (7) from below. Furthermore, the contact parts (11) are disposed so as neither to interfere with shavings reachable regions (21) nor to overlap the shavings reachable regions (21) in the press-fit direction, the shavings reachable regions (21) being imaginary extensions of the press-fit ribs (10) in the direction of protrusion thereof from the inner peripheral wall surfaces (14).
