Method for manufacturing engine poppet valve

Patent metadata

Field	Value
Publication number	US-11536167-B2
Application number	US-202117317773-A
Country	US
Kind code	B2
Filing date	May 11, 2021
Priority date	Nov 12, 2018
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

At a diameter-decreasing operation during manufacture of a poppet valve, an intermediate stem portion at which a valve head portion and an intermediate stem portion are made integral by way of a neck portion may be inserted between/among diameter-decreasing tools. Application of compressive forces from compressing surfaces of the diameter-decreasing tools may cause a part of the intermediate stem portion to be decreased in diameter and may cause a main body portion of a first stem portion to be formed and may cause formation of a stepped portion which is continuous with the main body portion, and formation, by an absence of decrease in diameter, of a second stem portion which is broader in girth than the main body portion and which is continuous with the neck portion and which is also continuous with the main body portion by way of the stepped portion.

First claim

What is claimed is:

1. A method for manufacturing a poppet valve for an engine having a valve head portion and a stem portion made integral by way of a neck portion that increases in diameter as one proceeds toward a tip end, the method for manufacturing the engine poppet valve characterized in that it comprises:
a forging operation in which an intermediate member made of metal at which the valve head portion and an intermediate stem portion are made integral by way of the neck portion is formed;
a diameter-decreasing operation in which an intermediate stem portion of the intermediate member is inserted between/among a plurality of diameter-decreasing tools that are formed so as to have stem member compressing surfaces and stem member inlet surfaces formed so as to be progressively distant from the stem member compressing surfaces and toward the tip end and that are arranged at a plurality of circumferentially equipartite locations about a circumference of the intermediate stem portion, application at the intermediate stem portion from a base end portion of compressive forces which are inwardly directed in a radial direction from the compressing surfaces of the respective diameter-decreasing tools which have been made to come in contact with a part of the intermediate stem portion that has been made to rotate while being displaced in relative fashion in a direction along a central axis thereof causing the part of the intermediate stem portion to be decreased in diameter from the base end portion and causing a main body portion of a first stem portion to be formed at the intermediate member and also causing formation by the compressing surfaces of a stepped portion which is continuous with the main body portion, and formation, by an absence of decrease in diameter of a remaining portion at the intermediate stem portion, of a second stem portion which is broader in girth than the main body portion and which is continuous with the neck portion and which is also continuous with the main body portion by way of the stepped portion;
a joining operation in which a stem end member having a same outside diameter as the main body portion is joined to a base end portion of the main body portion; and
a hole forming operation in which an intermediate hollow portion is formed in a region extending along an interior of the valve head portion, the neck portion, and the intermediate stem portion from a base end portion of the intermediate stem portion of the intermediate member is carried out after the forging operation but before the diameter-decreasing operation;
at the diameter-decreasing operation, a first hollow portion is formed at an interior of the main body portion simultaneous with the formation of the main body portion of the first stem portion in accompaniment to the decreasing of the diameter of the part of the intermediate stem portion by the stem member compressing surfaces, a reduced-diameter portion that is continuous with the first hollow portion is formed at an interior of the stepped portion simultaneous with the formation of the stepped portion by the stem member inlet surfaces, and a second hollow portion of large inside diameter that is continuous with the first hollow portion by way of the reduced-diameter portion is formed at an interior of the second stem portion which is of broad girth due to the absence of decrease in diameter of the remaining portion at the intermediate stem portion; and
at the joining operation, the stem end member is joined to the base end portion of the main body portion after the first hollow portion and the second hollow portion have been filled with coolant.

2. The method for manufacturing the engine poppet valve according to claim 1 wherein
the plurality of diameter-decreasing tools are a plurality of dies constituted so as to respectively be capable of synchronously engaging in reciprocating oscillatory motion in the radial direction of the intermediate stem portion of the intermediate member; and
at the diameter-decreasing operation, the intermediate member and the respective dies are made to engage in mutual relative rotation about the central axis, and the part of the intermediate stem portion undergoes decrease in diameter as the application of the compressive forces directed at the intermediate stem portion by the respective dies which engage in the reciprocating oscillatory motion and release thereof are made to occur in alternating and repetitive fashion.

3. The method for manufacturing the engine poppet valve according to claim 2 wherein at the diameter-decreasing operation the first stem portion is formed so as to be of smaller wall thickness than the second stem portion.

4. The method for manufacturing the engine poppet valve according to claim 2 wherein
at the forging operation, a face portion that will come in contact with a seat portion at a cylinder head when the valve is closed is formed at the valve head portion; and
at the diameter-decreasing operation, the stepped portion and the first stem portion are formed in such fashion as to cause length in a stem direction from a base end portion of the stepped portion to a tip end portion of the face portion to be less than length in the stem direction from a tipmost portion of a valve guide opening at the cylinder head to a tip end portion of the seat portion.

5. The method for manufacturing the engine poppet valve according to claim 1 wherein
the plurality of diameter-decreasing tools are a plurality of rollers for carrying out rolling which rotate in synchronous fashion that are provided with the stem member inlet surfaces which narrow as one proceeds from a location toward a base end to a location toward the tip end and the compressing surfaces which comprise cylindrical outer circumferential surfaces, and that are arranged so as to have mutually parallel rotational axes with a spacing between outer circumferential surfaces that is smaller than an outside diameter of the intermediate stem portion; and
at the diameter-decreasing operation, as the plurality of rollers for carrying out rolling which rotate in synchronous fashion in a same direction roll on and come in contact with the intermediate stem portion of the intermediate member, the compressive forces are applied and cause the part of the intermediate stem portion to undergo the decrease in diameter.

6. The method for manufacturing the engine poppet valve according to claim 5 wherein at the diameter-decreasing operation the first stem portion is formed so as to be of smaller wall thickness than the second stem portion.

7. The method for manufacturing the engine poppet valve according to claim 5 wherein
at the forging operation, a face portion that will come in contact with a seat portion at a cylinder head when the valve is closed is formed at the valve head portion; and
at the diameter-decreasing operation, the stepped portion and the first stem portion are formed in such fashion as to cause length in a stem direction from a base end portion of the stepped portion to a tip end portion of the face portion to be less than length in the stem direction from a tipmost portion of a valve guide opening at the cylinder head to a tip end portion of the seat portion.

8. The method for manufacturing the engine poppet valve according to claim 1 wherein at the diameter-decreasing operation the first stem portion is formed so as to be of smaller wall thickness than the second stem portion.

9. The method for manufacturing the engine poppet valve according to claim 1 wherein
at the forging operation, a face portion that will come in contact with a seat portion at a cylinder head when the valve is closed is formed at the valve head portion; and
at the diameter-decreasing operation, the st

Assignees

• Nittan Valva

Inventors

• KUNITAKE Koji
• Sato Daiki
• SASAGAWA Yuki

Classifications

• B21J7/16

  in rotary arrangements · CPC title

• F01L3/20 Primary

  Shapes or constructions of valve members, not provided for in preceding subgroups of this group · CPC title

• F01L3/14

  by means of a liquid or solid coolant, e.g. sodium, in a closed chamber in a valve · CPC title

• F01L3/18

  Liquid cooling of valve · CPC title

• F01L3/02 Primary

  Selecting particular materials for valve-members or valve-seats; Valve-members or valve-seats composed of two or more materials · CPC title