| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain the frame which maintains high frame rigidity and can be made lightweight in an impressive state by boring holes at a position surrounded with the skeleton part and rear end part of a frame main body and the raised part of a hitch pin, and forming ribs which project downward at the rear edges of the holes. SOLUTION: At the part surrounded by a skeleton part and a rear end part of a frame body 2 and a raised part of a hitch pin in the upper and intermediate registers, three large holes 8 are formed to cover the part entirely. The holes 8 are formed to make the frame main body 2 lightweight, and the ribs 23 which project downward are formed over the edges of the holes 8. While the formation of the ribs 23 maintains high rigidity, the frame can be made lightweight by providing the large holes 8. This impressive state of this frame can be secured since dowels 4, wood screws, etc., are hidden by the ribs 23 and not seen by a player through the large holes 8.</p> |
