Abstract: A die for extrusion molding includes a first face, a second face, a raw material supply section, a molding section, and a structure. The molding section has a second through hole that extends from the second face toward the first face so as to communicate with a first through hole. The structure is such that a material for the die is machined to form the material into a predetermined shape and to provide a machining-affected layer on an inner wall surface of the second through hole in the molding section, an oxidized layer is provided by heating the machining-affected layer to oxidize the machining-affected layer so as to convert the machining-affected layer into the oxidized layer, the oxidized layer is removed so that a treated surface is provided, and the treated surface is nitrided by ion implantation to provide a nitride layer.

Abstract: A die for extrusion molding includes a first face, a second face, a raw material supply section, and a molding section. The second face is provided opposite the first face. The raw material supply section includes a first through hole that extends from the first face toward the second face. The molding section includes a second through hole and a nitride layer. The second through hole extends from the second face toward the first face so as to communicate with the first through hole. The nitride layer is provided on an inner wall surface of the second through hole.

Abstract: The present invention relates to a communication line surge protecting system in which a quarter wavelength open circuit for a wavelength used is disposed in each of a central conductor line 1 and an external conductor line 2 so as to allow a signal with a predetermined communication wavelength to pass therethrough, while blocking signals with frequency components of lighting surge and the like, and in which a ground line is further provided in the central conductor line and a quarter wavelength short circuit for the wavelength used is disposed in each of the ground line and the external conductor line so as to block the signal with the predetermined communication wavelength, while allowing the signals with the frequency components of lighting surge and the like to pass therethrough. The signal of the predetermined wavelength used passes through the communication line and is insulated from the ground.

Abstract: The present invention relates to a communication line surge protecting system in which a quarter wavelength open circuit for a wavelength used is disposed in each of a central conductor line 1 and an external conductor line 2 so as to allow a signal with a predetermined communication wavelength to pass therethrough, while blocking signals with frequency components of lighting surge and the like, and in which a ground line is further provided in the central conductor line and a quarter wavelength short circuit for the wavelength used is disposed in each of the ground line and the external conductor line so as to block the signal with the predetermined communication wavelength, while allowing the signals with the frequency components of lighting surge and the like to pass therethrough.