Sumitomo Electric Hardmetal Corp.

Sumitomo Electric Industries, Limited

Kawasaki Jukogyo Kabushiki Kaisha

Yoshiji Sato

Kiichi Meguro

Minoru Yoshida

Shuhei Misumi

Makoto Abe

Keiji Osaka

Tomomi Moriya

Kazumasa Oishi

Masaaki Jindai

Ryusei Hamada

Rei Koike

Yuma Kawakami

Satoshi Suzuki

Junichi Tamura

Hisao Oka

Tatsuo Saito

Yukio Nomura

Katsuichi Omori

Yoshiharu Meguro

Masaki Jindai

Kenji Io

Kazumasa Kurizuka

A drill includes a body. The body includes a first cutting edge, and a second cutting edge apart from the first cutting edge to the back end side relative to the first cutting edge and formed in a recess traversing an outer peripheral portion of the body. In a side view of the body in a first direction in which a distance between a center axis of the body and a first outer end of the first cutting edge is seen the longest, a second outer end of the second cutting edge is located at the center axis side relative to the first outer end of the first cutting edge.

Drill

Drill bit

Drill head

A small diameter portion having an outside diameter smaller than a diameter of the drill is formed on a front end side of a body of the drill in which a cutting edge includes at least two portions, that is, a rotation center side cutting edge portion and an outer peripheral side cutting edge portion and point angles of the respective cutting edge portions reducing gradually from the rotation center side cutting edge portion to the outer peripheral side cutting edge portion. The cutting edge with the point angles varied is formed in the small diameter portion. A flat cutting edge having an inclination angle &#x3b2; of 30&#xb0; or less with respect to a line perpendicular to an axis of the drill is provided in a step portion formed between the small diameter portion and a large diameter portion.

A flute spread angle &#x3b8; in a drill axis-perpendicular section of a spiral flute is defined, a region of the flute taking part in chip treatment is formed along a first circle along an cutting edge of a concave curve and a second circle inscribed in this circle, both of the first circle and the second circle are circumscribed on a third circle expressing the web thickness, the radius R of the first circle and the radius Rof the second circle are in the range of 0.40 D to 0.70 D and in the range of 0.15 D to 0.30 D respectively, and a drill rotational direction front portion of the spiral flute is formed on the second circle to be closer to the drill center than a fourth circle having a diameter of 0.65 D.

Twist drill

A molding dieis constituted by an upper dieand a lower diewhich are made of a material transparent to an ultraviolet light, and has a cavityconstituted by grooves, whereas a resin injection gateand a resin exit gateare provided so as to communicate with the cavity. A junction of an optical fiberis inserted into the cavity. A UV-curable resin is injected into the cavitysurrounding an exposing portion of the glass optical fiberfrom the resin injection gatepositioned at one of coating ends of the optical fiber, whereas a part thereof is discharged from the resin exit gatepositioned at the other coating end. The ultraviolet light is emitted through the lower dieso as to cure the resin, thereby forming a reinforcement resin coating. As a consequence, bubbles can be prevented from occurring due to the residual air within the reinforcement resin coating in the junction of the optical fiber

MOLDING APPARATUS FOR A REINFORCEMENT RESIN COATING OF GLASS OPTICAL FIBER EXPOSING PORTION OF AN OPTICAL FIBER JUNCTION, METHOD FOR MOLDING REINFORCEMENT RESIN COATING OF A GLASS OPTICAL FIBER EXPOSING PORTION OF AN OPTICAL FIBER JUNCTION, AND OPTICAL FIBER CABLE

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Itami, Japan

Yoshiji Sato