Bending portion for endoscope, bending piece of bending portion for endoscope, endoscope, and injection molding mold for bending piece of bending portion for endoscope
A bending piece of a bending portion for endoscope is provided with: an annular wall portion; a plurality of wire inserting portions in which the wall portion has a first wall thickness; thin wall portions having a second wall thickness thinner than the first wall thickness; and a thick wall portion that is a part of the wall portion different from the thin wall portions between the plurality of wire inserting portions around a longitudinal axis, the thick wall portion formed to have a third wall thickness that is equal to or less than the first wall thickness and is thicker than the second wall thickness.
1. A bending portion for an endoscope, the bending portion comprising:
a plurality of bending pieces having contact portions on end portions facing each other in a longitudinal axis direction, the contact portions being in contact with each other, the plurality of bending pieces being mutually rotatable and being consecutively provided in the longitudinal axis direction, wherein each of the bending pieces comprises an annular wall portion having an inner peripheral surface and an outer peripheral surface formed around a longitudinal axis and having a predetermined length in the longitudinal axis direction, wherein the annular wall portion comprising;
a plurality of wire inserting portions in which the annular wall portion has a first wall thickness and through holes are formed, the through holes passing through the annular wall portion in the longitudinal axis direction, pulling wires configured to cause the bending pieces to rotate being inserted through the through holes;
a thin wall portion having a second wall thickness thinner than the first wall thickness, the thin wall portion being formed in a plurality of first areas of the annular wall portion, each of the plurality of first areas being between first adjacent pairs of the plurality of wire inserting portions around the longitudinal axis; and
a thick wall portion formed in a second area of the annular wall portion, the second area being between a second adjacent pair of the plurality of wire inserting portions around the longitudinal axis, the second adjacent pair being different from the first adjacent pairs, the second area being different from the first area, the thick wall portion having a third wall thickness that is equal to or less than the first wall thickness and is thicker than the second wall thickness;
wherein an entirety of the second area between the second adjacent pair of the plurality of wire inserting portions is the thick wall portion formed to have the third wall thickness; and
a gate mark of injection molding for molding the bending piece is formed on the thick wall portion.
2. The bending portion for endoscope according to claim 1 , wherein the gate mark is a protruding portion that is projectingly provided on an end surface of the thick wall portion in the longitudinal axis direction.
3. The bending portion for endoscope according to claim 1 , wherein an entirety of each of the plurality of first areas between the first adjacent pairs of the plurality of wire inserting portions is the thin wall portion formed to have the second wall thickness.