Mold set for paper binding

A paper sheet binding die set, comprising:

• a first die and a second die, each having an opposed surface comprising a plurality of tooth portions;
• wherein the first die and the second die are configured to face each other such that the plurality of tooth portions of the first die and the plurality of tooth portions of the second die are capable of meshing with each other;
• wherein each of the plurality of tooth portions of the first die has a substantially triangular cross section and a predetermined width, is provided in series on the opposed surface of the first die, and each comprises a bottom portion, a peak-top portion, and an inclined-surface portion extending at an incline from an edge of the bottom portion to a point on the peak-top portion on a lateral side of the respective tooth portion;
• wherein each of the plurality of tooth portions of the second die has a substantially triangular cross section and a predetermined width, is provided in series on the opposed surface of the second die, and each comprises a bottom portion, a peak-top portion, and an inclined-surface portion extending at an incline from an edge of the bottom portion to a point on the peak-top portion on a lateral side of the respective tooth portion;
• wherein the peak-top portion of each of the plurality of tooth portions of the first die has a length so as to extend over and beyond at least a part of the inclined-surface portion of a corresponding one of the plurality of tooth portions of the second die upon meshing of the first die and the second die;
• and
• wherein the paper sheet binding die set is configured to bind a plurality of stacked paper sheets such that the first die and the second die pressurize the plurality of stacked paper sheets from respective opposing sides of the plurality of stacked paper sheets.