Cold Extrusion Gear Forming with Pulsating Pressure and Fluid Injection
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Solution Overview
Problem
The existing cold extrusion process for forming gears requires additional processing steps like bonderizing and machining, which create stress risers and limit the use of net-formed gears under heavy loading conditions due to oxidation layers and machining-induced stress.
Innovation Solution
A die apparatus and method that apply pulsating pressure and fluid injection to eliminate the need for bonderizing and machining, improving grain flow and surface geometry, and forming gears without external machining, thereby reducing stress risers and enhancing gear integrity during heavy loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bonderizing process is applied to deposit phosphate coating, then lubrication coating is achieved, but oxidation layer creates stress risers requiring machining
Solution Approach 1:
The invention extracts and eliminates the harmful bonderizing process and oxidation layer from the manufacturing sequence. By using fluid injection during cold extrusion instead of post-processing bonderizing, the patent removes the source of stress risers and the need for subsequent machining operations, directly resolving the contradiction between ease of manufacture and gear reliability
Solution Approach 2:
The patent applies preliminary action by injecting lubricating fluid during the cold extrusion process itself, before any oxidation or coating steps would occur. This preliminary lubrication prevents the need for bonderizing and subsequent machining, eliminating stress risers before they can form and thereby improving gear strength while maintaining manufacturing efficiency
2Manufacturing precision
If machining is performed after extrusion, then surface geometry is improved, but stress risers are created in tooth root area
Solution Approach 1:
The invention extracts and eliminates the machining operation from the process sequence. By achieving adequate surface geometry through controlled cold extrusion with fluid injection, the patent removes the need for post-extrusion machining that would create stress risers in the tooth root area, thereby preserving gear integrity
Solution Approach 2:
The cold extrusion process with fluid injection serves itself to achieve both the necessary surface geometry and maintain structural integrity. The process self-regulates material flow and surface formation during extrusion, eliminating the need for separate machining operations that would compromise strength
3Manufacturing precision
If pulsating pressure with fluid injection is applied, then grain flow and surface geometry are improved, but process complexity increases
Solution Approach 1:
The patent employs hydraulics through fluid injection during cold extrusion to control material flow and improve grain structure. The injected fluid acts as a lubricant and pressure medium, enabling precise control of the extrusion process and surface geometry formation without requiring complex mechanical adjustment mechanisms
Solution Approach 2:
The patent applies periodic action through pulsating pressure during extrusion. The pulsating pressure pattern controls material flow rhythmically, improving grain flow and surface geometry while preventing defects. This periodic action is achieved through the injection system rather than complex mechanical oscillators
4Productivity
If bonderizing and machining steps are eliminated, then processing time is reduced, but gear strength under heavy loading may be compromised
Solution Approach 1:
The patent applies preliminary action by implementing proper lubrication and controlled material flow during the cold extrusion process itself. This preliminary control of grain flow and surface formation eliminates the need for subsequent bonderizing and machining steps, maintaining both productivity and gear strength for heavy loading applications
Solution Approach 2:
The cold extrusion process with fluid injection serves itself to produce gears with adequate surface geometry and grain flow structure. The process self-regulates to eliminate the need for post-processing steps, thereby maintaining productivity while producing gears capable of withstanding heavy loading without compromising strength
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
The solution enables the formation of net-formed gears with improved strength and reduced stress risers, eliminating the need for phosphate coatings and external machining, resulting in enhanced gear life and reduced processing steps.
Implementation Method 1
The high frequency unit vibrates to cause pulsation of the upper punch
Implementation Method 2
The fluid in the chamber lubricates and cools the work piece during extrusion
Data Source
AI summary
A method of forming an article such as a helical gear and an apparatus for forming the article are provided. The method includes applying pulsating pressure downward to extruding the work piece and, while the pressure is applied downward, injecting fluid to surround the work piece in fluid. The method eliminates pickling processes and phosphate lube coatings typically required for extrusion and external machining steps subsequently required to remove the coating. Extrusion of a cold net-formed article is thus possible due. An apparatus for carrying out the method is also provided.