Stapler

A stapler, in which sheets are stapled by a non-metal staple, the staple including a crown portion and a pair of leg portions respectively bent and extending in a first direction from both ends of the crown portion in a second direction, the second direction being a longitudinal direction of the crown portion and perpendicular to the first direction, the stapler comprising:

• a penetrating part including a pair of cutting blades which are disposed at an interval in the second direction, wherein holes are formed in the sheets and the pair of leg portions of the staple penetrate the sheets by penetrating and withdrawing the cutting blades into and from the sheets in the first direction,
• wherein blade portions that form the holes in the sheets are respectively provided in the cutting blades at their tip end sides in the first direction,
• wherein an interval in the second direction between the pair of cutting blades at the tip end sides in the first direction where the blade portions are provided is narrower than an interval in the second direction between the pair of cutting blades at base end sides which are opposite to the tip end sides in the first direction,
• wherein an inner side of one of the pair of the cutting blades and an inner side of the other of the pair of the cutting blades are facing to each other in the second direction,
• wherein inner stepped portions are respectively provided on the inner side of the one of the cutting blades and the inner side of the other of the cutting blades such that an interval in the second direction between the inner side of the one of the cutting blades and the inner side of the other of the cutting blades is widened from the tip end sides to the base end sides in the first direction, the inner stepped portions defining a staple support portion adapted to support the leg portions of the staple,
• wherein outer stepped portions are respectively provided on an outer side of the one of the cutting blades which positions in an opposite side in the second direction of the inner side of the one of the cutting blades and an outer side of the other side of the cutting blades which positions in an opposite side in the second direction of the inner side of the other of the cutting blades such that an interval in the second direction between the outer side of the one of the cutting blades and the outer side of the other of the cutting blades is widened from the tip end sides to the base end sides in the first direction, the outer stepped portions defining a hole expansion portion adapted to expand an interval in the second direction between the holes penetrating the sheets during the cutting blades penetrating the sheets and before the staple penetrates the sheets,
• wherein each of the cutting blades includes:
• a first penetrating portion which straightly extends in the first direction at the tip end side of the cutting blade from the staple support portion on the inner side and the hole expansion portion on the outer side;
• and
• a second penetrating portion which straightly extends in the first direction at the base end side of the cutting blade from the staple support portion on the inner side and the hole expansion portion on the outer side, and
• wherein the staple support portion is provided on the inner side of the cutting blade at a boundary between the first penetrating portion and the second penetrating portion.