Patent ID: 7690855
Filing Date: 2010-04-06
Classification: B42F

Abstract:
1. A binding tool for documents or the like, comprising: a base portion that is formed of a metal plate; rings that are each mounted on said base portion so as to be selectively changed into a closed ring posture to bind documents or the like and an opened ring posture to open a part of a closed ring for insertion of the documents or the like; and a switching mechanism that is mounted on said base portion and includes a switching lever for switching said rings between said closed ring posture and said opened ring posture; wherein said switching lever has a base end and a free end, and a cam member is provided on said base end of said switching member for adjusting the degree of opening/closing of each of said individual rings according to a rotated position of said free end of said switching lever; said cam member has a cam main body and a pair of camshafts that protrude from opposite side surfaces of said cam main body; said base portion is formed with a pair of bearing portions spaced apart and opposing each other with the cam member disposed therebetween, each camshaft engaging a respective one of said bearing portions, and said bearing portions are each formed of an inner surface of a curved portion where a part of said base portion is curved to a front surface side thereof; wherein said bearing portions each has a substantially semicircular shape in cross-section, with an open side of the semicircular shape directed toward a rear surface side of said base portion; said pair of bearing portions defining edges that oppose each other, and the base portion defining an opening disposed between said edges of the bearing portions; said cam main body having side surfaces, each side surface being provided with a contact portion having an inner surface portion of substantially semi-circular shape in cross-section, which has a radius larger than a radius of an outer surface of said bearing portion that opposes said inner surface portion; said inner surface portions of the contact portions being substantially in contact with the outer surfaces of the respective bearing portions when the rings are in the closed ring posture, and said contact portions preventing the camshafts from being downwardly displaced from the bearing portions during shifting from the closed ring posture to the open ring posture.