To miniaturize a linking structure by rotatably connecting the structure with a link rotating around the upper part of a side wall and a link connecting with a handle at a hole part having a curve part.

When a handle 4 is moved clockwise around a fulcrum 3 until a linear part 4a of the handle 4 fits onto a table frame 1, a link 9 rotates counterclockwise around a fulcrum 8. A roller 10 rotates counterclockwise from a curve part of a hole 7 having the curve part to the downward linear part. Bar parts 6, 6 connecting with links 9, 9 at the roller 10 move toward the right of a linear part 7a of the holes 7, 7 having the curve part. The bar parts 6, 6 are moved on the linear part under the holes 7, 7 having the curve part by the links 9, 9, and thereby, cutting a rail inserted into a groove in a die part 12.