Sango Co., Ltd.

Kentaro Nozu

Masashi Ota

Koji Suzuki

Michiharu Nakagaki

In extrusion processing in which diameter reduction is performed by pressing a raw pipe having a core bar inserted therein into a die having a small inner diameter portion on its tip end side, a differential thickness pipe having a thick-walled portion at its tip end can be molded using a core bar having a small cross-section portion formed at its tip end. It is also possible to mold a differential thickness pipe having a thick-walled part at an intermediate axial position by using a raw pipe having a thin-walled portion at its tip end. For example, such a raw pipe can be molded by extrusion processing using a core bar having no small cross section portion at its tip end, prior to the above-described formation of the thick-walled portion. When higher dimensional accuracy is required, a so-called 'counter punch' may be used in the formation of the thick-walled portion.

Extrusion molding method for differential thickness pipe and extrusion molding apparatus for differential thickness pipe

A clamp member and a counter pressure member are hingedly connected together about a rotary axis, and a fitting portion of a fitting protrusion that is positioned in a fitting recess is located at a foreside in an advancing direction of the pipe relative to a position where a bending operation of the pipe is initiated, and a mating portion at which a first groove part of the clamp member and a second groove part of a counter pressure member mate is located at a backside in the advancing direction of the pipe relative to the position where the bending operation of the pipe is initiated. The counter pressure member comprises a first member supported rotatably about the rotary axis, a second member detachably connected to the first member, and a third member detachably connected to the second member, which are connected together by a common connecting member (e.g., bolt).

Pipe bend die unit

A pipe bend die unit comprises a clamp member having a first groove part of half-circular cross section on an outer peripheral surface thereof with a fitting recess extending in a peripheral direction by a first predetermined length on a planar surface perpendicular to a rotary axis, and a counter pressure member having a second groove part of half-circular cross section formed on an outer peripheral surface thereof, and a fitting protrusion extending in a peripheral direction by a second predetermined length from a tip end portion of the second groove part. The fitting protrusion is positioned in the fitting recess so that the first and second groove parts are combined to form a pipe-receiving groove of half-circular cross section. The counter pressure member and the clamp member are hingedly connected to one another so as to be rotatable relative to each other about the rotary axis.

Pipe bend die unit, and pipe bending apparatus having the unit

A pipe bend die unit includes a bend die that comprises a clamp member and a counter pressure member, wherein the clamp member has a first groove part of half-circular cross section and a fitting recess extending in a peripheral direction by a first predetermined length on a planar surface perpendicular to a rotary axis. A fitting protrusion of the counter pressure member is positioned in the fitting recess to form a pipe-receiving groove of half-circular cross section, so that the counter pressure member and the clamp member are hingedly connected to one another about the rotary axis so as to be rotated relative to each other. The fitting recess possesses width expanding end face areas, where a clearance between opposing end faces is enlarged in a predetermined distance range including at least a radially outer end portion, from the rotary axis toward a radial outside.

A bend die comprises a clamp member having a first groove part of half-circular cross section on its outer peripheral surface with a fitting recess formed on the first groove part and extending in a peripheral direction by a first predetermined length on a planar surface perpendicular to a rotary axis, and a counter pressure member having a second groove part of half-circular cross section formed on its outer peripheral surface, and a fitting protrusion extending in a peripheral direction by a second predetermined length from a tip end portion of the second groove part. The fitting protrusion is positioned in the fitting recess so that a pipe-receiving groove of half-circular cross section is formed. The first and second groove parts are hingedly connected to one another about the rotary axis so as to be rotated relative to each other.

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Nagakute, Japan

Kentaro Nozu