Ntn Corporation

Tsuneaki Hiraoka

Shintaro Suzuki

Tatsuro Sugiyama

Masazumi Kobayashi

Naoki Nakagawa

Yuuki Tabuchi

Yuichi Asano

Hiromi Nagai

Yoshiya Mano

Masami Yamaguchi

Katsuhiro Sakurai

Kiyohiro Suzuki

Takeshi Shimasawa

Yuichiro Kitamura

Daisuke Kagawa

Toru Nakagawa

Masamichi Shinbo

Eri Hirayama

Provided is a heat treatment apparatus (), including: a conveying device (), which is configured to convey a rod-shaped workpiece (W) at a predetermined velocity along an axial direction of the workpiece (W); and a heating device () including a heating coil () configured to inductively heat the workpiece (W) being conveyed to a quenching temperature, wherein the heating coil () includes a first heating section (A) and a second heating section (B), which are coupled to each other in series along the axial direction of the workpiece (W), and is electrically connected to a single high-frequency power supply (), and wherein a coil pitch (D) of the second heating section (B) arranged relatively on a front side in a conveying direction for the workpiece (W) is larger than a coil pitch (D) of the first heating section (A) arranged relatively on a rear side in the conveying direction.

Heat treatment equipment and heat treatment method

When a rod-shaped workpiece (W) having an outer peripheral surface with a circular cross section is inductively heated to a quenching temperature while being conveyed at a predetermined velocity along an axial direction of the rod-shaped workpiece (W), the rod-shaped workpiece (W) being currently conveyed is heated to a predetermined temperature equal to or lower than the quenching temperature by a first heating coil (A), which is electrically connected to a first high-frequency power supply () and has a constant output. Then, the rod-shaped workpiece (W) being currently conveyed is heated so as to be maintained at the quenching temperature by a second heating coil (B), which is electrically connected to a second high-frequency power supply () and has a constant output.

Heat treatment method of rod-shape workpiece

A method of manufacturing an outer joint member of a constant velocity universal joint includes forming cup and shaft members of medium carbon steel, preparing, as the cup member, a cup member having cylindrical and bottom portions integrally formed by forging, and a joining end surface formed on an outer surface of the bottom portion, and preparing, as the shaft member, a shaft member having a joining end surface to be joined to the bottom portion of the cup member. The method also includes bringing the joining end surfaces of the cup and shaft members into abutment against each other, and welding the cup and shaft members from an outer side of the cup member to an abutment portion between the cup and shaft members in a radial direction of the cup members.

Method for manufacturing outer joint member for constant-velocity universal joint and outer joint member

When a plurality of outer rings (R) are sequentially and inductively heated to a target temperature by energizing a heating coil () elongated more than each of the plurality of outer rings (R), which are made of steel and retained coaxially by a retaining unit (), while relatively moving the outer rings (R) and the heating coil () in an axial direction, an output of the heating coil () is varied in consideration of the number of outer rings (R) present in an opposing region of the heating coil ().

Method for thermally treating ring-shaped member

A manufacturing method is used for an outer joint member of a constant velocity universal joint. The outer joint member includes a cup section having track grooves formed in its inner periphery, which are engageable with torque transmitting elements, and a shaft section formed at a bottom portion of the cup section. The manufacturing method includes welding the cup and shaft members by irradiating a beam to joining end portions of the cup and shaft members, causing an outer surface including the welded portion to be formed into a flat smooth surface by removal processing, irradiating ultrasonic waves to the flat smooth surface with one probe at an incident angle which prevents total reflection in a circumferential angle beam flaw detection method, and setting a focal point of the ultrasonic waves to positions from a surface to an inside of the welded portion, to thereby perform inspection.

Method for manufacturing outer joint member of constant velocity universal joint and ultrasonic flaw detection-inspection method for a welded portion

In an outer joint member of a constant velocity universal joint, a cup member and a shaft member are made of medium to high carbon steel and welded together. The cup member has a bottomed cylindrical shape that is opened at one end, and includes a cylindrical portion, a bottom portion, and a short shaft section of a solid shaft shape protruding from the bottom portion and having a joining end surface. The shaft member has a solid shaft shape and a joining end surface. The joining end surfaces of the cup and shaft members are brought into abutment against each other, and a high energy intensity beam is radiated from an outer side in a radial direction to form a welded portion. A structure of a molten metal at the welded portion is in a mixed phase of ferrite and granular cementite.

Constant velocity universal joint outer joint member and manufacturing method for same

A power transmission shaft including a male spline formed in an outer periphery thereof, and a diameter increasing portion formed on a part of a tooth bottom of the male spline, which is located on an opposite side to an axial end of the power transmission shaft. The tooth bottom of the male spline has a substantially constant circumferential width extending up to an axial region of the diameter increasing portion. The diameter increasing portion includes a chamfered portion formed in the axial region of the diameter increasing portion, the chamfered portion connecting the tooth bottom and a tooth flank of the male spline to each other to reduce a tooth groove width.

Power transmission shaft and spline-processing method

A method of manufacturing an outer joint member of a constant velocity universal joint includes forming cup and shaft members using medium carbon steel, preparing, as the cup member, a cup member having cylindrical and bottom portions integrally formed, and a joining end surface formed on an outer surface of the bottom portion, preparing, as the shaft member, a shaft member having a joining end surface to be joined to the bottom portion of the cup member, and bringing the joining end surfaces of the cup and shaft members into abutment against each other. The method also includes welding the cup and shaft members from an outer side of the cup member to an abutment portion between the cup and shaft members in a radial direction of the cup member under a state in which a hollow cavity portion is formed inside the abutment portion.

A hollow shaft material is provided with, on an outer peripheral surface side thereof, for example, a movable induction heating coil wrapped therearound. While a high-frequency current with a predetermined frequency is caused to flow through the induction heating coil, the induction heating coil is axially moved to perform induction hardening of the hollow shaft material from the outer peripheral surface side. At this moment, the frequency of the high-frequency current caused to flow through the induction heating coil is set relatively low as to the small-diameter portions, which have a relatively small thickness, and the frequency of the high-frequency current caused to flow through the induction heating coil is set relatively high as to the large-diameter portion, which has a relatively small thickness.

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Shizuoka, Japan

Tsuneaki Hiraoka