Ngk Spark Plug Company, Limited

Satoru Ochiai

Haruki Yoshida

Takamitsu Mizuno

Atsushi Tsukada

Mitsunari Kariya

A processing apparatus for processing a workpiece by transferring the workpiece between a ram and a die block. At least one recessed die of a plurality of dies molds the workpiece into a bottomed tubular shape by a punch. A punch, among a plurality of punches, that has entered the recessed die exits from the recessed die with the formed workpiece being attached to the punch, together with the workpiece. Since the workpiece is transferred from the die block to the ram when the punch exits from the die, a step of moving the ram forward relative to the die block to transfer the workpiece from the die block to the ram can be omitted accordingly.

Processing apparatus, method for manufacturing molded product, and method for manufacturing spark plug electrode

A multi-diameter tubular body is cold-forged by forming a large-diameter hole portion in a formed body having a preliminary hole through subjection of the preliminary hole to deep hole forming and by punching out the bottom surface of the large-diameter hole portion to thereby form a small-diameter hole portion. Since a punch having a central protrusion on its forward end surface is used, an internal flaw is generated by dead metal in the inner circumferential surface of a depression, formed by the protrusion, in the bottom surface of the large-diameter hole portion. An outside diameter of a protrusion of a deep hole forming punch is rendered smaller than an inside diameter of the small-diameter hole portion to be formed later by punching out the bottom surface of the large-diameter hole portion. As a result, the internal flaw is removed when the small-diameter hole portion is formed.

Method for manufacturing cylindrical body having different diameters by cold forging

A method of manufacturing a metal fitting having a tool engagement portion engageable with a tool. The manufacturing method includes a cold forging process, wherein the cold forging process includes: a step (a) of forming a body portion having a first maximum length and a butt portion being continuous to the body portion and having a second maximum length larger than the first maximum length; and a step (b) of drawing at least a part of the butt portion in the axis direction, thereby forming the tool engagement portion.

Method for manufacturing metal fitting, method for manufacturing spark plug, and method for manufacturing sensor

There is provided a method of manufacturing a metal shell formed body by cold forging for a metal shell of a spark plug. In the manufacturing method, a semi-finished formed body is first provided with a second inner step without the formation of an annular front end portion. After the semi-finished formed body is inserted from its front end side into a die, a punch is pushed into the semi-finished formed body from its rear end side. By pushing the punch, an annular front-facing surface of the punch is pushed onto the second inner step so as to press a front end portion of the formed body against an annular front end portion forming part of the die. By such a forming step, the metal shell formed body is obtained in which the annular front end portion is formed by extrusion.

Manufacturing method of metal shell formed body for spark plug, manufacturing method of metal shell for spark plug, and spark plug manufacturing method

A spark plug includes an insulator having an axial hole, a first inner circumferential surface, a second inner circumferential surface whose diameter is greater than that of the first inner circumferential surface, and a ledge portion connecting the first and the second inner circumferential surfaces. The spark plug also includes a center electrode having a large-diameter portion, a projection portion, and a circular columnar leg portion that projects into a space surrounded by the first inner circumferential surface. The spark plug includes a seal portion which fixes the center electrode within the axial hole. When C&#x3c;A, A&#x2212;C&#x2266;B&#x2212;A, where A represents a diameter of an imaginary cylinder having the minimum diameter required for surrounding the projection portion, B represents a maximum diameter of the large-diameter portion, and C represents an average diameter of the leg portion present in the space surrounded by the first inner circumferential surface.

Spark plug

A method for manufacturing electrodes for a spark plug that reduces manufacturing time. The method includes a supply step of supplying a workpiece to a die for extrusion forming, wherein the die has a supply hole and an extrusion hole located adjacent to the supply hole for forming the workpiece to have a predetermined cross-sectional shape. The supply hole has a cross section greater than a cross section of the extrusion hole. The method also includes a forming step of pushing the workpiece, supplied to the supply hole, through the extrusion hole so as to form the workpiece into a shape corresponding to the cross section of the extrusion hole. In the supply step, the workpiece is supplied such that a plurality of workpieces form a vertical line in the die.

Method of manufacturing a spark plug electrode and a spark plug

A method of manufacturing a center electrode of a spark plug, comprising the steps of forming a cylindrical electrode member having a medium diameter portion and a small diameter portion and forming a barrel portion by extruding the medium diameter portion when the value of (S1&#x2212;S2)/S1&#xd7;100) is 30 or more, S1 being the cross-sectional area of a cross-section of the medium diameter portion perpendicular to an axial direction, and S2 being the cross-sectional area of a cross-section of each small diameter portion perpendicular to the axial direction.

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Nagakute, Japan

Satoru Ochiai