An umbrella part metallic sodium insertion device for inserting rod-shaped metallic sodium into a hollow part of a hollow valve; a melting device for melting the metallic sodium in the hollow part by inserting a push rod from an opening into the hollow part of the hollow valve, in which the metallic sodium has been inserted by the device, and, while pushing the rod-shaped metallic sodium in the hollow part, heating the umbrella part to a temperature at which the metallic sodium is melted; a stem part cooling device for cooling a stem part of the hollow valve, in which the metallic sodium has been melted by the melting device, to a temperature lower than the temperature at which the metallic sodium is melted; and a stem part metallic sodium insertion device for inserting rod-shaped metallic sodium into the hollow part which has been cooled by the device.

An umbrella part metallic sodium insertion device for inserting rod-shaped metallic sodium into a hollow part of a hollow valve; a melting device for melting the metallic sodium in the hollow part by inserting a push rod from an opening into the hollow part of the hollow valve, in which the metallic sodium has been inserted by the device, and, while pushing the rod-shaped metallic sodium in the hollow part, heating the umbrella part to a temperature at which the metallic sodium is melted; a stem part cooling device for cooling a stem part of the hollow valve, in which the metallic sodium has been melted by the melting device, to a temperature lower than the temperature at which the metallic sodium is melted; and a stem part metallic sodium insertion device for inserting rod-shaped metallic sodium into the hollow part which has been cooled by the device.

A hollow valve having optimized interior stem geometry, whose valve stem has surface-enlarging structuring on an inner surface is provided. Also provided is a method for manufacturing a valve body of such a hollow valve, wherein the method comprises: providing a bowl-shaped semi-finished product having an annular wall that surrounds a cavity, and having a base section, followed by lengthening the wall with an inserted, structured mandrel, and lastly, reducing an outer diameter of the annular wall without a mandrel to obtain a predetermined valve stem outer diameter of a valve to be manufactured.

A hollow valve having optimized interior stem geometry, whose valve stem has surface-enlarging structuring on an inner surface is provided. Also provided is a method for manufacturing a valve body of such a hollow valve, wherein the method comprises: providing a bowl-shaped semi-finished product having an annular wall that surrounds a cavity, and having a base section, followed by lengthening the wall with an inserted, structured mandrel, and lastly, reducing an outer diameter of the annular wall without a mandrel to obtain a predetermined valve stem outer diameter of a valve to be manufactured.

Disclosed is a method for the production of a valve body of a hollow chamber valve, said method comprising: providing a bowl-shaped semi-finished product having an annular wall, which surrounds a hollow chamber, and a bottom portion, followed by a lengthening of the wall and a final reducing of an outer diameter of the annular wall in order to obtain a predetermined valve shaft outside diameter of a valve that is to be produced. Further disclosed is a hollow chamber valve produced by means of said method.

The invention relates to a process for manufacturing an internally cooled valve, said process involving providing an externally at least partly cylindrical semifinished product (2), creating or increasing the depth of an at least partly cylindrical cavity in the semifinished product (2) in a hot-working procedure using a male die such that a valve blank is formed; during the hot-working procedure, a recess on an end face of the male die forms a structure on the bottom of the cavity.

The invention relates to a process for manufacturing an internally cooled valve, said process involving providing an externally at least partly cylindrical semifinished product (2), creating or increasing the depth of an at least partly cylindrical cavity in the semifinished product (2) in a hot-working procedure using a male die such that a valve blank is formed; during the hot-working procedure, a recess on an end face of the male die forms a structure on the bottom of the cavity.

The present invention provides a hollow engine valve achieving high durability while suppressing an increase in manufacturing cost, and a manufacturing method therefor. 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, thereby forming the valve main body intermediate member into a valve main body semifinished product provided with the semifinished product valve head portion and a semifinished product valve stem portion; 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, thereby reducing the diameter of the semifinished product valve stem portion and increasing the length of the stem of the semifinished product valve stem portion, to form the valve main body semifinished product into the valve main body.

The present invention provides a hollow engine valve achieving high durability while suppressing an increase in manufacturing cost, and a manufacturing method therefor. 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, thereby forming the valve main body intermediate member into a valve main body semifinished product provided with the semifinished product valve head portion and a semifinished product valve stem portion; 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, thereby reducing the diameter of the semifinished product valve stem portion and increasing the length of the stem of the semifinished product valve stem portion, to form the valve main body semifinished product into the valve main body.

A sliding mechanism 1 includes a first sliding member 10 and a partner second sliding member 20 configured to slide relative to the first sliding member 10. The first sliding member 10 includes a matrix phase 11 and a hard phase 13 that is harder than the matrix phase 11, in which the hard phase 13 is embedded in the matrix phase 11 in a dispersed state. The second sliding member 20 includes a base 21 and a surface-treatment layer 23 that is formed on the sliding surface 20 of the base 21 and is harder than the matrix phase 11.