Engine Valve Boss Forming With Alternating Loads and Stem Retention
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Solution Overview
Problem
Existing methods for manufacturing engine valve intermediate products with boss portions struggle to achieve high strength in piston or vane portions while maintaining toughness in the neck portion and face portion, and face challenges in forming the boss portion at a desired location separated from the valve head forming portion.
Innovation Solution
A method involving a stem retaining operation using intermediate jigs to stabilize the stem forming portion, followed by a stem enlarging operation that applies alternating compressive and tensile forces to form a boss portion with increased hardness, allowing the boss portion to be formed at any desired location without heat treating the entire valve, thus maintaining toughness in the neck portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat treatment is applied to the entire engine valve to increase strength, then the piston portion and vane portion achieve high strength, but the neck portion loses toughness and becomes prone to fracture
Solution Approach 1:
The patent applies local quality by differentiating the material properties of different valve portions. The boss portion (piston/vane) is made of high-strength material to withstand high-temperature exhaust gas, while the neck portion is designed with appropriate toughness to absorb impact. This selective property assignment resolves the contradiction by ensuring each portion has the optimal properties for its specific functional requirements.
Solution Approach 2:
The patent segments the engine valve into distinct portions with different material characteristics. The valve is divided into the boss portion (for piston/vane), the neck portion, and the stem portion, allowing independent optimization of each segment's properties. This segmentation enables the boss portion to be heat-treated for strength while the neck portion maintains toughness.
2Ease of manufacture
If the boss portion is formed by cutting from a stem member, then the piston portion and vane portion can be created, but the manufacturing process becomes complex and material is wasted
Solution Approach 1:
The patent applies preliminary action by forming the boss portion with the correct geometry and dimensions during the initial forging process, rather than creating it later through cutting. The boss portion is pre-formed as an integral part of the stem member, eliminating the need for subsequent cutting operations and associated material waste.
Solution Approach 2:
The patent merges the formation of the boss portion with the forging process itself. Instead of separate operations for creating the boss portion and the stem member, the process combines these into a single forging operation that produces both features simultaneously, reducing manufacturing steps and material waste.
3Manufacturing precision
If the boss portion is formed at a location separated from the valve head forming portion, then the piston portion can be properly positioned, but the stem-enlarged portion formation becomes unstable due to insufficient grippable length
Solution Approach 1:
The patent introduces an intermediary retaining structure (such as a collar or groove) on the stem member that provides a stable gripping point for the forming operation. This intermediary feature allows the boss portion to be formed at the desired location separated from the valve head, while the retaining structure ensures stability during the stem-enlarged portion formation process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the formation of a high-strength boss portion for the piston or vane portion while maintaining toughness in the neck portion, allowing for precise placement and reducing manufacturing costs by avoiding heat treatment of the entire valve.
Implementation Method 1
a stem enlarging operation in which compressive forces are applied from both ends of the intermediate product and the boss portion is formed as the intermediate product is made to rotate and alternating loads that cause tensile forces and compressive forces to act in repeated and alternating fashion in a direction parallel to a central axis of the stem at the outer circumferential surface of the stem forming portion are applied thereto
Data Source
AI summary
A method of manufacturing an engine valve intermediate product with a boss portion formed in integral fashion at an outer circumferential surface at an intermediate location on a stem forming portion. The manufacturing method may comprise a stem retaining operation in which an intermediate location of the stem forming portion is retained by a plurality of intermediate jigs removably installable radially with respect to a center of the stem forming portion, and a base end portion is retained by a base end jig. The manufacturing method may further comprise a stem enlarging operation in which compressive forces are applied from both ends of the intermediate product and the boss portion is formed as the intermediate product is made to rotate and alternating loads that cause tensile forces and compressive forces to act in repeated and alternating fashion at the outer circumferential surface of the stem forming portion are applied.