A first connecting portion (31) and a second connecting portion (33) slide over a first guide link (17) and a second guide link (19), respectively, when an operation point (OP) of a reciprocating linear motion mechanism (38) moves from an initiating position to a terminating position. A second acute angle (θ2) formed between the second guide link (19) and a supporting surface (15) is greater than a first acute angle (θ1) formed between the first guide link (17) and the supporting surface (15).