Method for manufacturing injection hole member

A method for manufacturing an injection hole member formed with a taper hole, which serves as at least a part of an injection hole, the taper hole being formed so that a central axis of the taper hole is inclined with respect to an axis of a base material of the injection hole member in a thickness direction of the base material and a diameter of the taper hole increases in a direction from an end surface of the base material to the other end surface of the base material, the method comprising the steps of:

• forming a lead hole in the base material through punch press with a punch, the lead hole being formed so that a central axis of the lead hole is inclined with respect to the axis of the base material in the thickness direction thereof and a diameter of the lead hole is substantially constant along an extending direction of the central axis of the lead hole;
• and
• forming a taper hole in the base material by widening the lead hole with a taper punch, whose tip end is inserted into the lead hole in a state where a central axis of the taper punch is inclined to the same side as the central axis of the lead hole with respect to the axis of the base material in the thickness direction thereof, the taper punch being formed so that a diameter of the taper punch decreases toward the tip end thereof, wherein
• the injection hole member is formed so that an intersection line between a first reference plane, which is a virtual plane perpendicular to the central axis of the lead hole, and an inner peripheral surface of the lead hole is round in shape, and
• the injection hole member is formed so that an intersection line between a second reference plane, which is perpendicular to the central axis of the taper punch, and an outer peripheral surface of the taper punch is in an elliptic shape or an oval shape, whose major axis is directed in an extending direction of a reference axis, which is a line perpendicularly crossing an intersection line between a virtual plane, which includes the central axis of the taper punch and the axis of the base material in the thickness direction thereof, and the second reference plane on the second reference plane.

A method for manufacturing an injection hole member formed with a taper hole, which serves as at least a part of an injection hole, the taper hole being formed so that a central axis of the taper hole is inclined with respect to an axis of a base material of the injection hole member in a thickness direction of the base material and a diameter of the taper hole increases in a direction from an end surface of the base material to the other end surface of the base material, the method comprising the steps of:

• forming a lead hole in the base material through punch press with a punch, the lead hole being formed so that a central axis of the lead hole is inclined with respect to the axis of the base material in the thickness direction thereof and a diameter of the lead hole is substantially constant along an extending direction of the central axis of the lead hole;
• and
• forming a taper hole in the base material by widening the lead hole with a taper punch, whose tip end is inserted into the lead hole in a state where a central axis of the taper punch is inclined to the same side as the central axis of the lead hole with respect to the axis of the base material in the thickness direction thereof, the taper punch being formed so that a diameter of the taper punch decreases toward the tip end thereof, wherein
• the injection hole member is formed so that an intersection line between a first reference plane, which is perpendicular to the central axis of the lead hole, and an inner peripheral surface of the lead hole is in an elliptic shape or an oval shape, whose major axis is directed in an extending direction of a first reference axis, which is an intersection line between the first reference plane and a virtual plane including the central axis of the lead hole and the axis of the base material in the thickness direction thereof, and
• the injection hole member is formed so that an intersection line between a second reference plane, which is perpendicular to the central axis of the taper punch, and an outer peripheral surface of the taper punch is in an elliptic shape or an oval shape, whose major axis is directed in an extending direction of a second reference axis, which perpendicularly crosses an intersection line between a virtual plane, which includes the central axis of the taper punch and the axis of the base material in the thickness direction thereof, and the second reference plane on the second reference plane.

A method for manufacturing an injection hole member formed with an injection hole for injecting fluid, the method comprising the steps of:

• forming a taper hole in a base material of the injection hole member through punch press so that a diameter of the taper hole increases along a direction from an end surface of the base material to the other end surface of the base material;
• and
• forming a straight hole in the base material by widening a smaller diameter opening of the taper hole through punch press so that an inner peripheral surface of the straight hole connects to an inner peripheral surface of the remaining taper hole, wherein
• the injection hole is provided by the taper hole and the straight hole.

A method for manufacturing an injection hole member formed with an injection hole for injecting fluid, the method comprising:

• a lead hole forming step of forming a lead hole by punching out a base material of the injection hole member with a lead hole punch along a direction from an upstream end surface toward a downstream end surface of the base material so that a central axis of the lead hole is inclined with respect to an axis of the base material in its thickness direction, and of forming an enlarged diameter portion in an edge of a downstream end opening of the lead hole by breaking the edge of the downstream end opening of the lead hole with the lead hole punch, and
• an injection hole forming step of forming the injection hole so that a diameter of the injection hole increases along a direction from the upstream end surface to the downstream end surface of the base material and an axis of the injection hole in an injection direction is inclined with respect to the axis of the base material in its thickness direction by inserting a taper punch, whose diameter decreases toward its tip end, into the lead hole from a downstream end of the lead hole and by widening the lead hole, and of forming a concave portion, which caves in radially outward from an inner peripheral surface providing the injection hole, in an edge of a downstream end opening of the injection hole by remaining at least a part of the enlarged diameter portion when the injection hole is formed.