Metal Pipe Blow Forming with Two-Stage Cooling Rate Control
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Solution Overview
Problem
The existing forming apparatuses for metal pipes often result in products that are either too brittle due to rapid cooling, leading to reduced toughness, and struggle to achieve suitable strength and toughness characteristics for specific applications.
Innovation Solution
A forming apparatus and method that control the cooling rate of metal pipes by using a cooling medium after initial die contact cooling, allowing for adjustable hardenability and toughness through timing and medium selection, including the use of gas as a non-contaminating cooling medium for uniform cooling and oxide layer removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cooling is performed by contact with the die after forming, then the metal pipe is cooled quickly and strength is increased, but the metal pipe becomes brittle and toughness is lowered
Solution Approach 1:
The cooling process is divided into two distinct stages: first die contact cooling to rapidly reduce temperature and increase strength, then cooling medium cooling to slow down the cooling rate and improve toughness. This segmentation allows each stage to optimize for its specific purpose without compromising the other property.
Solution Approach 2:
Die contact cooling is performed first as a preliminary action to quickly strengthen the metal pipe before the second cooling stage. This preliminary strengthening ensures the pipe has sufficient strength before the tougher but slower cooling process begins.
2Productivity
If only die contact cooling is performed, then cooling efficiency is high, but the cooling rate is too fast and causes brittleness
Solution Approach 1:
The single die contact cooling process is segmented into two phases: initial die contact cooling for high efficiency and subsequent cooling medium cooling for controlled rate. This maintains the productivity benefit while eliminating the toughness degradation.
Solution Approach 2:
A cooling medium is introduced as an intermediary between the metal pipe and the environment after die contact cooling. This intermediary allows for controlled heat extraction at a slower rate, improving toughness while maintaining overall cooling efficiency.
3Strength
If cooling rate is increased to improve strength, then hardenability increases, but toughness decreases
Solution Approach 1:
The cooling process uses periodic action with two distinct rates: a fast cooling rate phase followed by a slow cooling rate phase. This periodic variation in cooling rate allows the metal pipe to achieve both high strength and good toughness by experiencing different thermal conditions at different times.
Solution Approach 2:
The cooling rate parameter is changed in two stages: first increased for strength enhancement, then decreased for toughness improvement. This dynamic parameter adjustment allows optimization of both mechanical properties that would be conflicting under constant cooling conditions.
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 approach enables the production of metal pipes with tailored strength and toughness characteristics, enhancing their suitability for various applications by adjusting cooling rates and hardenability, while maintaining product quality and preventing oxide layer contamination.
Implementation Method 1
cooling of the metal pipe (80) by a cooling medium (90)
Implementation Method 2
cooling the metal pipe by maintaining a state where the metal pipe is brought into contact with the die
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Provided are a forming apparatus and a forming method, in which it is possible to obtain a forming product having suitable characteristics. A control unit (70) makes cooling of the metal pipe (80) by a cooling medium be performed, by controlling an operation of a blow forming die (13) such that the blow forming die (13) is opened and controlling the cooling unit (90) such that the cooling unit (90) brings the cooling medium into contact with the metal pipe (80), subsequently to completion of forming by the blow forming die (13). In this manner, by performing the cooling by contact with the cooling medium, it is possible to slow down a cooling rate, compared to the cooling by contact with the blow forming die (13), and thus quenching to enhance the toughness of the metal pipe (80) becomes possible. Further, in a case of performing cooling by using the cooling medium, by adjusting a contact time with the cooling medium, the amount of the cooling medium, the temperature of the cooling medium, or the like, it is possible to easily perform adjustment of hardenability, compared to the cooling by contact with the die.