Band tightening device

A band tightening device comprising:

• a housing having a slide surface;
• a gripping mechanism that pulls a band with reciprocation along the slide surface;
• and
• a reciprocating mechanism that causes the gripping mechanism to reciprocate along the slide surface, wherein
• the gripping mechanism includes
• a chuck base slidably in contact with the slide surface, and
• a pressing gripper that presses the band against the chuck base,
• the chuck base includes
• a pair of formation walls each having a contact surface in contact with the slide surface and constituting an entry path of the band, and
• a band support portion continuous with the pair of formation walls so as to span the pair of formation walls,
• the band support portion includes an inclined opposing surface facing the entry path and inclined with respect to the contact surface so as to approach the contact surface as approaching an entrance of the band, and
• the pressing gripper slidably presses the band against the inclined opposing surface of the chuck base.