Hot-press Stamping Cooling Method for Uniform Thin Steel Sheet Quenching
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Solution Overview
Problem
Hot press forming of thin steel sheets faces issues with shape distortion and quality variations due to nonuniform cooling, particularly around ejection holes, resulting from differences in cooling speed and air entrainment during the cooling process.
Innovation Solution
A cooling method and apparatus that control the ejection amount of refrigerant, initiating precooling with a suppressed ejection amount followed by increased ejection during main cooling, to ensure uniform cooling and prevent air entrainment, thereby reducing temperature variations and shape distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the flow amount of cooling water is increased to shorten the cooling time period, then productivity is improved, but cooling uniformity deteriorates causing quality variation and shape distortion
Solution Approach 1:
The patent applies dynamics by transitioning from a static cooling system (constant flow rate) to a dynamic cooling system where the flow rate of cooling water is continuously adjusted during the cooling process. The flow rate is controlled to be higher at the initial stage and gradually reduced, allowing rapid heat removal when the steel sheet is hottest while preventing excessive cooling and air entrainment at later stages, thus achieving both short cooling time and uniform cooling distribution.
Solution Approach 2:
The patent implements parameter changes by varying the flow rate parameter of cooling water throughout the cooling process. Instead of maintaining a constant flow rate, the system adjusts the flow rate parameter dynamically - starting with a high flow rate for rapid cooling and then reducing it to maintain cooling uniformity, thereby resolving the contradiction between productivity and manufacturing precision.
2Speed
If cooling water is ejected at a predetermined ejection amount from the beginning of cooling, then cooling speed is maintained, but air bumping or entrainment occurs concentrically centering on the ejection hole generating cooling unevenness
Solution Approach 1:
The patent applies preliminary action by controlling the cooling water flow rate to be particularly high at the initial stage of cooling when the steel sheet temperature is highest and cooling demand is greatest. This preliminary high-flow action ensures rapid heat removal when needed most, then the flow rate is reduced as cooling progresses to prevent air entrainment and maintain uniformity, thus achieving both high cooling speed and cooling uniformity.
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 effectively suppresses shape distortion and quality variations by maintaining uniform cooling across the thin steel sheet, improving the accuracy and consistency of the formed product.
Implementation Method 1
quench hardening by rapid cooling is done
Implementation Method 2
a channel of water communicated with ejection holes of the refrigerant which are provided in a plurality of places in the surface of the mold
Implementation Method 3
a channel for sucking the supplied water
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
In hot press forming a thin steel sheet K, when cooling the thin steel sheet K by supplying a refrigerant to an ejection hole (27) communicated from a supply path (28) inside a lower mold (12), precooling in which an ejection amount per unit time period of the refrigerant from the ejection hole (27) is suppressed is carried out, and thereafter, main cooling is carried out by increasing the ejection amount per unit time period.