Axle box suspension of railcar bogie and method of producing the same
A railcar bogie axle box suspension axle beam includes an end portion d at a tip end, a tubular portion at the end portion and being open at both car width direction sides. The tubular portion includes: a first semi-tubular portion integrally formed with a main body portion; a second semi-tubular portion brought into contact with the first semi-tubular portion from one side in the car longitudinal direction; and a bolt fastening the second semi-tubular portion to the first. The first semi-tubular portion includes: a flat opposing surface contacting the second semi-tubular portion; and a hole into which the bolt is inserted. The second semi-tubular portion includes: a flat opposing surface contacting with the first semi-tubular portion surface; a flat machining reference surface formed at an opposite side of the opposing surface; and a hole extending in a direction perpendicular to the opposing surface, the bolt inserted into the hole.
1. An axle box suspension of a railcar bogie,
the axle box suspension comprising:
an axle beam including
an axle beam main body portion extending in a car longitudinal direction from an axle box accommodating a bearing supporting an axle and
an axle beam end portion provided at a tip end of the axle beam main body portion, a tubular portion at the axle beam end portion and open at both car width direction sides;
a core rod inserted into an internal space of the tubular portion in a car width direction;
an elastic bushing interposed between the tubular portion and the core rod; and
a receiving seat provided at a bogie frame, both end portions of the core rod being connected to the receiving seat,
the tubular portion including
a first semi-tubular portion integral with the axle beam main body portion,
a second semi-tubular portion which is brought into contact with the first semi-tubular portion from one side in the car longitudinal direction, and
a bolt by which the second semi-tubular portion is fastened to the first semi-tubular portion in the car longitudinal direction,
the first semi-tubular portion including
a first opposing surface that is flat and in surface contact with the second semi-tubular portion and
a first hole extending perpendicular to the first opposing surface, the bolt being inserted into the first hole,
the second semi-tubular portion including
a second opposing surface that is flat and in surface contact with the first opposing surface,
a flat machining reference surface at an opposite side of the second opposing surface and configured to stably support the second semi-tubular portion on a surface plate of a machining device, wherein the flat machining reference surface is a surface of a protrusion extending out of a generally convex side of the second semi tubular portion, and
a second hole extending perpendicular to the second opposing surface, the bolt being inserted into the second hole.
2. The axle box suspension according to claim 1 , wherein:
the first hole of the first semi-tubular portion is a drilled hole;
the second hole of the second semi-tubular portion is a threaded hole; and
the bolt is inserted from the first semi-tubular portion toward the second semi-tubular portion.
3. The axle box suspension according to claim 1 , further comprising a positioning pin attached to the tubular portion and engaging with the elastic bushing, wherein:
a concave portion with which the pin engages is at an outer peripheral surface of the elastic bushing; and
the pin is attached to an inner peripheral surface of the first semi-tubular portion.
4. A method of producing an axle box suspension of a railcar bogie,
the axle box suspension including an axle beam,
the axle beam including
an axle beam main body portion extending in a car longitudinal direction from an axle box accommodating a bearing supporting an axle and
an axle beam end portion provided at a tip end of the axle beam main body portion, a tubular portion being formed at the axle beam end portion and being open at both car width direction sides,
the tubular portion including
a first semi-tubular portion formed integrally with the axle beam main body portion,
a second semi-tubular portion which is brought into contact with the first semi-tubular portion, and
a bolt by which the second semi-tubular portion is fastened to the first semi-tubular portion,
the method comprising:
an opposing surface machining step of providing the second semi-tubular portion at a machining device such that a flat machining reference surface of the second semi-tubular portion contacts a surface plate of the machining device, and flattening a flat opposing surface of the second semi-tubular portion, the opposing surface being formed to be in surface contact with the first semi-tubular portion, the machining reference surface being formed at an opposite side of the opposing surface;
a hole forming step of forming a hole at the second semi-tubular portion which is in a same posture as in the opposing surface machining step, the bolt being inserted into the hole; and
an inner peripheral surface machining step of subjecting an inner peripheral surface of the tubular portion to complete circle machining with the second semi-tubular portion staked on the first semi-tubular portion.
5. The method according to claim 4 , wherein:
the hole forming step is a threaded hole forming step of forming a threaded hole into which the bolt is inserted; and
the bolt is inserted from the first semi-tubular portion toward the second semi-tubular portion.