Engine valve forging system

摘要

An engine valve forging system includes a molding forging die having a circular hole stem molding portion continued to a tip end of a head type molding portion, to mold an engine valve by extrusion-forging a material from the head type molding portion to the stem molding portion by an upper die, and a stem guide forging die which is coaxially disposed to communicate with a tip end of the stem molding portion, and has a guide portion for a stem portion of an engine valve extruded from the stem molding portion, and a plurality of stem curve restraining portions having a shape gradually tapering toward a central shaft line from a rear end portion to a tip end portion are formed continuously along the central shaft line of the guide portion in the guide portion, to be capable of manufacturing high-precision engine valves with less stem curve.

主权项

1. An engine valve forging system, comprising:
a molding forging die for an engine valve, the molding forging die having a circular hole shaped stem molding portion which is contiguous with a tip end of a head type molding portion and adapted to extrusion-forge a material on the head type molding portion to the stem molding portion by an upper die; and at least one stem guide forging die which is disposed coaxially with the stem molding portion, and which has a plurality of stem curve restraining portions, separated from the stem molding portion, for forming a stem portion of an engine valve extruded from the stem molding portion, wherein each stem curve restraining portion is tapered gradually toward a central shaft line of the stem curve restraining portion over the entire area thereof from its rear end portion to its tip end portion, such that the stem curve restraining portion has a rear end opening portion whose inner diameter is greater than that of a tip end opening portion of the stem molding portion; wherein the tip end of the stem molding portion is communicated with a rear end opening of one stem curve restraining portion; wherein said plurality of stem curve restraining portions are arranged in a linear array along their central shaft line; and wherein the tip end of each stem curve restraining portion is communicated with a rear end opening portion of another stem curve restraining portion having a larger inner diameter than the tip end of the respective stem curve restraining portion.