Patent ID: 7970339

Claim:
A bookbinding apparatus, comprising: a sheet bundle storing device to store a sheet bundle; a grasping device to grasp the sheet bundle stored in the sheet bundle storing device; a square spine forming device to form a square spine, wherein a pair of forming members bend a coversheet bonded onto a back section of the sheet bundle grasped by the grasping device; a pressure force table including a basis weight of the coversheet as a parameter; an operation device for inputting the basis weight of the coversheet; and a pressure force controlling device to control the square spine forming device according to the basis weight of the coversheet with reference to the pressure force table, so as to fold the coversheet bonded onto the sheet bundle with an appropriate pressure force so that an appropriate adhesion force between the coversheet and the sheet bundle, and a superior quality of appearance of a booklet are obtained, wherein the pressure force controlling device varies the pressure force so as to increase the pressure force as the basis weight of the coversheet increases.