Bolt pre-tightening assisting device of press machine

The utility model relates to the field of mechanism device manufacturing and discloses a bolt pre-tightening assisting device of a press machine. The press machine comprises a machine seat. A pillar is arranged on the machine seat. A pre-tightening bolt penetrates through the pillar. An end portion of the pre-tightening bolt is fixedly connected with a pre-tightening nut. The bolt pre-tightening device is characterized in that an opening is formed in the pillar. A heat insulating layer is machined on the pre-tightening bolt in the opening in a covered mode. A coil is formed on the heat insulating layer in a wound mode. The coil is sequentially and electrically connected with a transformer and an alternating current power supply. According to the bolt pre-tightening device of the press machine, the electro-magnetic induction vortex heating technology is used for heating the bolt, the bolt is evenly heated and expanded to an expected elongation and then the nut is tightly screwed so as to achieve the aim of pre