Internal Combustion Engine Valve Hardness via Primary Forging
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Solution Overview
Problem
Existing methods for manufacturing internal combustion engine valves fail to provide sufficient hardness and wear resistance, especially for diesel engines using low-grade fuel, due to issues in the thickness adjustment step that taper the valve head, exposing softer inner layers and reducing the effectiveness of radial slip deformations.
Innovation Solution
The method involves forming a tapered face during primary forging, allowing the valve head to retain its initial hardened grain structure, eliminating the need for machining in the thickness adjustment step and enhancing the secondary forging process to create radial slip deformations, thus increasing the valve face's hardness and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the valve head is tapered in the thickness adjustment step to remove excessive material, then the valve head thickness is reduced to specification, but the grain flow lines are cut and exposed softer inner layers are revealed, reducing hardness of the valve face
Solution Approach 1:
The invention applies preliminary action by forming the tapered face geometry during the primary forging step before the thickness adjustment machining. This preliminary shaping ensures that the grain flow lines are established in the correct orientation before any material removal occurs, preventing the cutting of grain flow lines that would expose softer inner layers and reduce valve face hardness.
2Reliability
If radial slip deformations are created in the valve face through secondary forging, then wear resistance is improved, but if the grain flow lines have been cut by prior machining, the hardness is insufficient
Solution Approach 1:
The invention performs the preliminary action of establishing the tapered face geometry with proper grain flow orientation during primary forging, before the secondary forging creates radial slip deformations. This sequence ensures that when radial slip deformations are introduced, they occur in material with intact grain flow lines, achieving both high hardness and wear resistance.
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 approach results in valves with improved hardness and blow-through characteristics, reducing material waste and costs, while maintaining high wear resistance and corrosion resistance, meeting stringent exhaust gas regulations.
Implementation Method 1
a step of primary forging in which a bulging portion at one end of a rod material is forged to form a generally disk-shape valve head by means of a primary forging die unit having a first die and a first punch
Implementation Method 2
a step of secondary forging in which a periphery of the disk-shape valve head is further forged to create therein slip deformations by means of a secondary forging die unit having a second die and a second punch
Data Source
Figure 1
Figure 2(a)~2(f)
Figure 3(a)~3(c)
AI summary
A method of manufacturing a valve for an internal combustion engine, comprising: a primary forging step for forming a generally disk-shape valve head; a thickness adjusting step of machining an excessively thick portion to adjust the thickness of the disk-shape valve head; and a secondary forging step for forming a valve face (16) by forging the periphery of the valve head to create radial slip deformations along the periphery of the disk-shape valve head. In the primary forging step, a tapered face (16a) is formed on the periphery of the disk-shape valve head. In the thickness adjustment step, only the front end of the disk-shape valve head is machined. Dense grain flow lines induced in the tapered face (16a) in the primary forging are grown more densely in the secondary forging, enhancing the hardness of the valve face. Thus, a rectangular corner of the disk-shape valve head needs not be tapered, which facilitates saving the valve material and reducing thickness adjustment time.