Step Heating of Hot-Stamping Blanks for Uniform Soaking
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Solution Overview
Problem
The hot stamping process faces challenges in ensuring uniform heating of blanks with different thicknesses, leading to potential overheating and reduced weldability, corrosion resistance, and increased risk of delayed fracture due to differences in heating rates and soaking times.
Innovation Solution
A method involving step heating and soaking of blanks in a heating furnace with multiple temperature sections, where the temperature condition satisfies the equation (Tg−Ti)/Lt<0.025° C./mm, allowing for precise control of heating rates and minimizing differences in soaking times between blanks of varying thicknesses, thereby preventing overheating and enhancing weldability and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple blanks of different thicknesses are simultaneously heated in a heating furnace, then productivity is improved, but heating uniformity deteriorates leading to quality differences
Solution Approach 1:
The heating furnace is divided into multiple heating zones with different temperature settings. Thinner blanks are placed in zones with lower temperatures while thicker blanks are placed in zones with higher temperatures, allowing each blank to receive appropriate heating intensity and achieve uniform heating simultaneously.
Solution Approach 2:
Different regions of the heating furnace are assigned different temperature characteristics tailored to the specific thickness requirements of blanks in those regions. This local customization of heating conditions ensures that each blank experiences optimal heating regardless of its thickness.
2Productivity
If heating temperature is increased to improve heating speed, then productivity is improved, but risk of overheating increases leading to reduced weldability and increased delayed fracture
Solution Approach 1:
The heating process uses dynamic temperature control where the temperature in each zone is adjusted based on the thickness and heating stage of blanks. During initial heating, temperatures are controlled to prevent overheating, while during soaking stage, temperatures are optimized for uniform heat distribution, allowing flexible adaptation to different heating requirements.
Solution Approach 2:
Before final high-temperature soaking, blanks undergo preliminary heating in zones with controlled temperatures. This staged approach prevents sudden thermal shocks and overheating, preparing the blanks gradually for the final heating stage while maintaining material properties.
3Productivity
If heating temperature is increased to improve heating speed, then productivity is improved, but corrosion resistance deteriorates
Solution Approach 1:
The heating furnace is divided into multiple heating zones with different temperature settings. Thinner blanks are placed in zones with lower temperatures while thicker blanks are placed in zones with higher temperatures, allowing each blank to receive appropriate heating intensity and achieve uniform heating simultaneously.
Solution Approach 2:
The heating process uses dynamic temperature control where the temperature in each zone is adjusted based on the thickness and heating stage of blanks. During initial heating, temperatures are controlled to prevent overheating, while during soaking stage, temperatures are optimized for uniform heat distribution, allowing flexible adaptation to different heating requirements.
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 ensures that blanks of different thicknesses are heated uniformly, reducing hydrogen embrittlement, improving corrosion resistance, and enhancing weldability, resulting in hot-stamped parts with consistent properties and reduced risk of delayed fracture.
Implementation Method 1
inserting a blank into a heating furnace including a plurality of sections with different temperature ranges; step heating the blank in multiple stages
Implementation Method 2
heating the blank in a heating furnace including a plurality of sections with different temperature ranges
Implementation Method 3
uses a phase transformation of materials and a change in microstructures during the processes; soaking the blank at a temperature of about Ac3 to about 1000° C.
Implementation Method 4
forming a molded body by hot-stamping the transferred blank; and cooling the formed molded body
Implementation Method 5
cooling the formed molded body
Data Source
AI summary
A method of manufacturing a hot-stamped part includes: inserting a blank into a heating furnace including a plurality of sections with different temperature ranges; step heating the blank in multiple stages; and soaking the blank at a temperature of about Ac3 to about 1,000° C., wherein in the step of heating the blank, a temperature condition in the heating furnace satisfies the following equation: 0<(Tg−Ti)/Lt<0.025° C./mm, where Tg denotes a soaking temperature (° C.), Ti denotes an initial temperature (° C.) of the heating furnace, and Lt denotes a length (mm) of step heating sections.