Hollow Engine Valve Flow Forming Without Critical Welds
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Solution Overview
Problem
Current methods for producing hollow valves for internal combustion engines are costly, require numerous processing steps, and often involve critical welding points that can be operationally disadvantageous, while also not optimizing material utilization and productivity.
Innovation Solution
A method involving the formation of a bowl-shaped semi-finished product from a cylindrical blank, followed by flow forming and rotary swaging to create a hollow valve body with improved material properties and reduced outer diameter, allowing for efficient cooling medium integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional methods (forging, turning, welding) are used to produce hollow valves, then the valve structure can be achieved, but the production cost increases and productivity decreases due to multiple processing steps
Solution Approach 1:
The patent combines multiple traditional manufacturing steps (forging, turning, welding) into a single flow forming process. The hollow valve body is produced in one continuous operation using a flow forming die and hydraulic press, eliminating the need for separate forging, turning, and welding operations, thereby reducing both cost and increasing productivity
Solution Approach 2:
The patent uses a preform as the starting material that already has the basic hollow structure. This preform is then finished through flow forming in a single step, avoiding the need for multiple intermediate processing steps. The preform preparation is done in advance, allowing the final shaping to be completed efficiently in one operation
2Manufacturing precision
If turning or milling of the cavity is performed to create hollow valve, then the cavity shape can be achieved, but the production cost increases significantly
Solution Approach 1:
The patent replaces traditional mechanical turning or milling operations with a flow forming process. Instead of using cutting tools to remove material and shape the cavity, the invention uses controlled plastic deformation through a flow forming die, which shapes the cavity through material flow rather than material removal, significantly reducing production cost while maintaining precision
Solution Approach 2:
The patent changes the manufacturing approach from subtractive (turning/milling) to formative (flow forming). By controlling parameters such as hydraulic pressure, die geometry, and material flow, the cavity shape is achieved through controlled deformation, maintaining manufacturing precision while eliminating the high costs associated with extensive turning or milling operations
3Reliability
If welding is used to close the cavity in hollow valve production, then the cavity can be sealed, but critical welding points are created that are disadvantageous for operation
Solution Approach 1:
The patent extracts or eliminates the welding step from the manufacturing process. Instead of creating a hollow valve that requires welding to seal the cavity, the flow forming process directly produces the sealed hollow structure in one piece, removing the source of critical welding points and their associated operational risks
Solution Approach 2:
The flow forming process inherently creates the sealed cavity structure without requiring additional welding operations. The die geometry and forming process itself ensure proper sealing and closure of the cavity, making the structure self-sealing and eliminating the need for separate welding steps that would create critical points
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 enhances productivity, reduces material waste, minimizes critical welding points, and achieves superior material properties, including improved cooling and reduced susceptibility to thermal stress, while maintaining high surface quality and precise tolerances.
Implementation Method 1
flow forming the tubular wall above a flow forming mandrel
Implementation Method 2
flow forming rollers can be radially and axially offset to one another during the flow forming
Implementation Method 3
reducing an outer diameter of the tubular wall after the flow forming
Implementation Method 4
reducing of the outer diameter of the tubular wall can take place by means of rotary swaging
Implementation Method 5
improved internal cooling can be achieved by means of a cooling medium, e.g. sodium
Implementation Method 6
filling a cooling medium, in particular sodium, into the cavity
Data Source
AI summary
A production method for a valve body of a hollow valve includes providing a preform with a valve head and a tubular wall which surrounds a cylindrical cavity. The tubular wall is flow formed above a flow forming mandrel which is inserted into the cavity in order to increase a length of the tubular wall. A hollow valve produced by flow forming is also disclosed.