Abstract: A manufacturing method for a hollow engine valve comprises: a step of forming, by forging, a solid round bar as a material of a valve main body into a valve main body intermediate member provided with a semifinished product valve head portion corresponding to a valve head portion and a solid stem portion corresponding to a valve stem portion; a step of performing cutting process with respect to the valve main body intermediate member across the solid stem portion and the semifinished product valve head portion for forming a semifinished product hollow hole with a bottom corresponding to a hollow hole; and a step of performing necking process with respect to the valve main body semifinished product for squeezing the semifinished product valve stem portion step by step, to form the valve main body semifinished product into the valve main body.

Abstract: The present invention provides a hollow engine valve achieving high durability while suppressing an increase in manufacturing cost, and a manufacturing method therefor.

Abstract: The present invention provides a hollow engine valve achieving high durability while suppressing an increase in manufacturing cost, and a manufacturing method therefor.

Abstract: The present invention provides a hollow engine valve achieving high durability while suppressing an increase in manufacturing cost, and a manufacturing method therefor.

Abstract: The present invention provides a method for producing a hollow engine valve, with which the production process can be simplified and the processing precision can be improved. To this end, the present invention provides a method for producing a hollow engine valve (1) which is provided with a valve main body (10) in which a hollow hole (10c) is formed along a valve umbrella part (10a) and a hollow shaft part (10b), wherein a solid round bar (11) forming the material of the valve main body (10) is molded to a semi-finished article (12) by means of a single hot-forging process, the semi-finished article (12) is subjected to rotary swaging whereby the semi-finished article (12) is molded into a semi-finished article (13), the semi-finished article (13) is subjected to necking whereby the semi-finished article (13) is molded into the valve main body (10), and a shaft end sealing member (20) is joined to the end part of the hollow shaft part (10b) of the valve main body (10).

Abstract: A method for manufacturing a hollow engine valve includes a step for performing rotational plastic working on a follow engine valve body semifinished product which is configured from a shaft part and a valve umbrella part forming portion connected to the shaft part. A columnar hole part is formed from the shaft part to an enlarged diameter section of the valve umbrella part forming portion to thereby reduce the diameter of the shaft part. A necking step follows the rotational plastic working step, necking the hollow engine valve body semifinished product to thereby reduce the outer diameter and the inner diameter of the shaft part. A sealing step seals the leading end of the shaft part to obtain the hollow engine valve.

Abstract: The present invention provides a method for producing a hollow engine valve, with which the production process can be simplified and the processing precision can be improved. To this end, the present invention provides a method for producing a hollow engine valve (1) which is provided with a valve main body (10) in which a hollow hole (10c) is formed along a valve umbrella part (10a) and a hollow shaft part (10b), wherein a solid round bar (11) forming the material of the valve main body (10) is moulded to a semi-finished article (12) by means of a single hot-forging process, the semi-finished article (12) is subjected to rotary swaging whereby the semi-finished article (12) is moulded into a semi-finished article (13), the semi-finished article (13) is subjected to necking whereby the semi-finished article (13) is moulded into the valve main body (10) , and a shaft end sealing member (20) is joined to the end part of the hollow shaft part (10b) of the valve main body (10).

Abstract: A method for producing a hollow engine valve is disclosed which involves gradually reducing the size of the outer diameter and inner diameter of a hollow shaft of a semi-finished product sequentially inserting the hollow shaft into a plurality of molding holes having different hole shapes so as to gradually extend the length of the hollow shaft, and forming the hollow shaft into a predetermined shape by sequentially performing a drawing process. The semi-finished product is subjected to heat treatment such that the hardness thereof is equal to or less than a predetermined hardness, and the maximum thickness between the hollow shaft and an umbrella portion connected to the bottom edge of the hollow shaft is formed to be thicker than the thickness of the hollow shaft by means of a molding hole of a die which is adjusted to have a specific length and maximum inner diameter.

Abstract: Disclosed is a method—for producing an engine valve (V) filled with metallic sodium (Na) within by means of: forming a stem section (S), which has a hollow section (H), at an intended size by successively drawing the stem section (S) using dies (D1, D2, Dx, Dx+1, Dn) in a manner so as to causing the size of the outer diameter and the inner diameter of the stem section (S) to contact in a stepwise fashion; and inserting metallic sodium (Na) into the hollow section (H) of the stem section (S)—wherein after drawing the stem section (S) until the inner diameter of the hollow section (H) of the stem section (S) has become a prescribed size (steps S11-S15) and then inserting the block-shaped solid metallic sodium (Na) into the hollow section (H) of the stem section (S) (step S16), the stem section (S) is further drawn (steps S17 and S18).

Abstract: A method for manufacturing a hollow engine valve includes a step for performing rotational plastic working on a follow engine valve body semifinished product which is configured from a shaft part and a valve umbrella part forming portion connected to the shaft part. A columnar hole part is formed from the shaft part to an enlarged diameter section of the valve umbrella part forming portion to thereby reduce the diameter of the shaft part. A necking step follows the rotational plastic working step, necking the hollow engine valve body semifinished product to thereby reduce the outer diameter and the inner diameter of the shaft part. A sealing step seals the leading end of the shaft part to obtain the hollow engine valve.

Abstract: Provided is a method for producing an engine valve by subjecting a stem portion having a hollow part to a drawing treatment using a series of dies such that the outer diameter and inner diameter of the stem portion become smaller in steps and the stem portion is thereby molded to the desired size, whereby, after the stem portion has been subjected to the drawing treatment until the inner diameter of the hollow part of the stem portion has reached a specific size, sodium metal in the form of a solid block is introduced to the hollow part of the stem portion, and a protective agent made from solid paraffin or naphthalene is also introduced to the hollow part of the stem portion such as to form a barrier between the sodium metal and the atmosphere, after which the stem portion is further subjected to a cold drawing treatment.

Abstract: Provided is a method for producing an engine valve by subjecting a stem portion having a hollow part to a drawing treatment using a series of dies such that the outer diameter and inner diameter of the stem portion become smaller in steps and the stem portion is thereby molded to the desired size, whereby, after the stem portion has been subjected to the drawing treatment until the inner diameter of the hollow part of the stem portion has reached a specific size, sodium metal in the form of a solid block is introduced to the hollow part of the stem portion, and a protective agent made from solid paraffin or naphthalene is also introduced to the hollow part of the stem portion such as to foam a barrier between the sodium metal and the atmosphere, after which the stem portion is further subjected to a cold drawing treatment.

Abstract: A method for manufacturing a hollow engine valve includes inserting a half-finished hollow shaft section in sequence into die holes which have different hole shapes, and sequentially drawing so as to reduce the outer diameter and the inner diameter of the hollow shaft section and stretch its length in stages. The half-finished product is subjected to heat treatment so that the hardness thereof is lower than or equal to a predetermined level. A shaft end sealing section is formed by increasing the wall thickness of the opening end of the hollow shaft section toward the inside of the opening and the gap in the shaft end sealing section is welded.

Abstract: A method for producing a hollow engine valve is disclosed which involves gradually reducing the size of the outer diameter and inner diameter of a hollow shaft of a semi-finished product sequentially inserting the hollow shaft into a plurality of molding holes having different hole shapes so as to gradually extend the length of the hollow shaft, and forming the hollow shaft into a predetermined shape by sequentially performing a drawing process. The semi-finished product is subjected to heat treatment such that the hardness thereof is equal to or less than a predetermined hardness, and the maximum thickness between the hollow shaft and an umbrella portion connected to the bottom edge of the hollow shaft is formed to be thicker than the thickness of the hollow shaft by means of a molding hole of a die which is adjusted to have a specific length and maximum inner diameter.

Abstract: In the disclosed method, an engine valve (V) filled with metallic sodium (Na) within is produced by means of hardening metallic sodium (Na)—that has been liquefied through heat-melting—into rods by linearly discharging the metallic sodium (Na) in a liquid hydrocarbon (120), thus cooling the metallic sodium, then inserting these rods into a hollow section (H) through the opening (M) of a stem section (S) , and then sealing the opening (M).

Abstract: Disclosed is a method—for producing an engine valve (V) filled with metallic sodium (Na) within by means of: forming a stem section (S), which has a hollow section (H), at an intended size by successively drawing the stem section (S) using dies (D1, D2, Dx, Dx+1, Dn) in a manner so as to causing the size of the outer diameter and the inner diameter of the stem section (S) to contact in a stepwise fashion; and inserting metallic sodium (Na) into the hollow section (H) of the stem section (S)—wherein after drawing the stem section (S) until the inner diameter of the hollow section (H) of the stem section (S) has become a prescribed size (steps S11-S15) and then inserting the block-shaped solid metallic sodium (Na) into the hollow section (H) of the stem section (S) (step S16), the stem section (S) is further drawn (steps S17 and S18).

Abstract: The present invention aims to provide a cast-coated paper having good sheet gloss, printability and productivity and a process for preparing it. Herein disclosed is a cast-coated paper obtained by applying a cast coating layer comprising a pigment and an adhesive on a base paper, and pressing and drying the cast coating layer in the wet state against a heated mirror finishing surface to finish it, characterized in that the cast coating layer contains 50 parts by weight or more of a kaolin having a particle size distribution containing 65% by volume or more of particles in the range of 0.4-4.2 ?m per 100 parts by weight of inorganic pigments and further contains a plastic pigment; as well as a process for preparing it.

Abstract: The present invention aims to provide coated papers for newsprint inks having fast ink drying properties comparable to those of conventional newsprint papers, without stickiness, and having good reproduction and sharpness of printed images comparable to those of coated papers printed using penetration drying type inks; as well as processes for preparing them. The invention provides for a coated printing paper for newsprint inks comprising a coating layer containing a pigment and an adhesive on a base paper, characterized in that the coating layer on the base paper has a coat weight of 4.0 g/m2 or more per side and that the coated paper has an oil absorbency under pressure of 20 g/m2 or more and a Bekk smoothness of 75 seconds or less; as well as a process for preparing the paper.

Abstract: A coated sheet for web offset printing which includes a pigment coating layer containing a pigment and an adhesive formed on a base paper, and a surface layer containing a surface-sizing agent and a plastic pigment formed on the pigment coating layer.

Abstract: A coated printing paper offering high gloss, no mottled impression, sufficiently practical levels of printability in terms of ink-drying property and surface peel strength, and good productivity achieved by elimination of deposits on the calender rolls, wherein the coated printing paper comprises a base paper and a coating layer comprising pigment and adhesive formed on the base paper, and wherein a surface layer comprising 100 weight-parts of thermoplastic copolymer with a glass-transition temperature of 80° C. or above and 3 to 100 weight-parts of surface sizing agent of styrene-acrylic, olefin or styrene-maleic acid copolymer type is formed on the coating layer.