Movable Hot Press Die Cooling for Shape Accuracy and Productivity

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Solution Overview

Problem

Conventional methods for manufacturing metal products with localized properties face challenges in achieving both shape accuracy and productivity, as they often result in defects due to uneven cooling and temperature differences within the formed product, necessitating prolonged bottom-dead-center holding times in the die.

Innovation Solution

A hot press apparatus with movable die parts that alternate between abutting and retracting positions during the bottom-dead-center holding period, allowing for controlled cooling rates and temperature distribution, ensuring shape accuracy without extending the holding time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the formed product is kept in the die until uniform temperature is reached, then shape accuracy is improved, but productivity deteriorates due to prolonged holding time

Engineering Contradiction:
Improveshape accuracyVSAvoidbottom-dead-center holding period
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The die structure is made dynamic by introducing movable die parts that can change position between abutting and retracted states during the holding period, allowing the cooling conditions to be adjusted dynamically rather than remaining static throughout the entire holding period

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The bottom-dead-center holding period is divided into periodic phases: an abutting period where the movable die part contacts the formed product for rapid cooling, and a non-abutment period where the die part retracts to allow slower cooling, creating a periodic cooling pattern that achieves uniform temperature distribution more efficiently

Inventive Principle:
Principle #19Periodic action

2Adaptability or versatility

If a gap is kept between the die and the formed product to reduce cooling rate, then local property distribution is improved, but shape accuracy deteriorates due to thermal contraction defects

Engineering Contradiction:
Improveproperty distributionVSAvoidshape accuracy
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The gap between the die and formed product is made dynamic rather than static, allowing the system to transition between contact (no gap) and non-contact (gap present) states during different phases of the holding period, enabling both rapid cooling for shape accuracy and slower cooling for property distribution

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The movable die part abuts the formed product during the abutting period to perform preliminary rapid cooling that establishes the basic shape accuracy before the non-abutment period begins, preventing thermal contraction defects from occurring in the first place

Inventive Principle:
Principle #10Preliminary action

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 apparatus ensures shape accuracy and property distribution in the formed product by controlling cooling conditions, reducing defects and maintaining uniform temperature distribution through adjustable cooling rates, thus enhancing manufacturing efficiency.

Implementation Method 1

a bottom-dead-center holding period for which the first die part and the second die part are at a bottom-dead center includes an abutment period for which the movable die part abuts the metal sheet and a non-abutment period for which the movable die part does not abut the metal sheet

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

as these portions experience thermal contraction during cooling, the formed product may develop defects of shape. Further, if there are large temperature differences within the formed product when the formed product is removed from the die, the formed product may deform due to thermal contraction

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentEP4129519B1Hot press apparatus and method of manufacturing hot-press-formed product
Publication Date: 2026.01.28 NIPPON STEEL CORPORATION
  • EP4129519B1 patent drawingFigure 1
  • EP4129519B1 patent drawingFigure 2
  • EP4129519B1 patent drawingFigure 3

AI summary

A hot press apparatus includes a first die part 2 and a second die part 3, and a control unit 9. At least one of the first and second die parts 2 and 3 includes a recess 3a in the surface facing the other die part in the direction of pressing. A movable die part 4 is provided in the recess 3a. The control unit 9 controls the movable die part 4 such that the bottom-dead-center holding period, for which the first and second die parts 2 and 3 are at the bottom-dead center, includes an abutment period for which the movable die part 4 abuts the metal sheet B and a non-abutment period for which the movable die part does not abut the metal sheet B.