Hot Press Cooling Sequence for Hard-Soft Zone Warpage Control
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Solution Overview
Problem
The existing hot press processing methods face unintended deformation issues in molded products with both hard and soft zones due to volume differences caused by crystal structure variations, leading to warpage and reduced processing accuracy.
Innovation Solution
A hot press processing method that includes heating, press-molding, and cooling steps, where a predetermined portion in the soft zone is given increased rigidity or hardness through specific cooling techniques, such as quenching or shaping, to suppress deformation and enhance processing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a workpiece is processed into a molded product including both hard zone (martensite) and soft zone (ferrite/bainite), then both high strength and extensibility are achieved, but unintended deformation and warpage occur due to volume difference between crystal structures
Solution Approach 1:
The patent applies preliminary action by increasing the rigidity or hardness of the predetermined portion in the soft zone before the cooling step. This is achieved by giving the predetermined portion a shape having higher rigidity (such as a bead shape) or by quenching it beforehand. This preliminary strengthening prevents unintended deformation and warpage that would otherwise occur during cooling due to volume differences between martensite and ferrite/bainite crystal structures, thereby maintaining processing accuracy while still achieving both strength and extensibility in the final molded product
2Strength
If martensite transformation is used to form hard zone, then high strength is obtained, but volume shrinkage occurs causing warpage in the soft zone
Solution Approach 1:
The patent applies preliminary anti-action by increasing the rigidity or hardness of the predetermined portion in the soft zone before cooling and martensite transformation occurs. This preliminary strengthening creates a counteracting effect that resists the volume shrinkage and warpage forces generated during martensite transformation in the hard zone. By preemptively reinforcing the soft zone structure, the patent counterbalances the detrimental shape changes while preserving the high strength benefits of martensite
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 method effectively suppresses unintended deformation and increases processing accuracy by forming both hard and soft zones in a single molded product, ensuring high strength and extensibility while preventing warpage during cooling.
Implementation Method 1
a heating step of heating the workpiece
Implementation Method 2
cooling a part of the workpiece press-molded in the press step and causing the part to undergo martensite transformation to form a hard zone
Implementation Method 3
cooling another part of the workpiece and causing the other part to undergo ferrite/bainite transformation to form a soft zone
Implementation Method 4
a predetermined portion in the soft zone is cooled after at least one of rigidity and hardness of the predetermined portion is increased
Data Source
AI summary
A hot press processing device 1 includes steps of: a heating step of heating a workpiece W; a press step of press-molding the workpiece W heated in the heating step; a cooling step of cooling a part of the workpiece W press-molded in the press step and causing it to undergo martensite transformation to form a hard zone Zh in the workpiece W, and cooling another part of the workpiece W and causing it to undergo ferrite/bainite transformation to form a soft zone Zs in the workpiece W. In the cooling step, the hot press processing device 1 cools a predetermined portion Zb in the soft zone Zs after increasing rigidity and hardness of the predetermined portion Zb.