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Heat Management in Hot Forming Applications

IP.com Disclosure Number: IPCOM000249044D
Publication Date: 2017-Jan-30
Document File: 2 page(s) / 265K

Publishing Venue

The IP.com Prior Art Database

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Heat Management Method for Hot-forming Applications (Invention Disclosure 83685310)

This invention addresses two different problems associated with hot forming process (figure 1) and hot forming tooling (figure 2):

1.      The effective management of heat during the forming and quenching process

2.      The effective manufacture of the tooling itself to achieve the necessary heat management using heat pipes and drilled holes.

Both these problems deal with the effective management of heat.

Quenching of the part (determined by cooling rate) during hot forming is a critical step in the process. The reason for this is the fact that quenching directly affects production rates as well as the surface and dimensional quality of the part as it undergoes phase changes during the forming process.  Material properties are continuously changing as the material cools and undergoes a transformation from the austenite phase into the martensite phase.  Too quick of a transformation will make the part less formable and create cracks.  When quenching is too slow, production rates go down! 

On the other hand, the way that the material is cooled and how uniformly it is cooled dictates its dimensional integrity and can affect the final properties of the part. For example, if one area forms and cools quicker than another, that location will be harder than the second softer area.  These temperature gradients cause the part to twist, causing the final part to deviate from its design intent and be dimensionally inaccurate (due to springback).

Description of Solution / Method

Hot Forming is an innovative process by which advanced ultra-high strength steel is formed into complex shapes more efficiently than with traditional cold stamping. Hot forming of parts therefore currently represents one of the most advanced lightweight solutions for the car body structure that simultaneously allows us to improve crash performance and passenger safety requirements.

Hot forming is a temperature and time-dependent process. With this method, parts are formed in their soft state at elevated temperatures and then quenched in the tool.  The hot forming process consists of the steps identified in figure 1: (1) eat treatment in furnace, (2) transfer from furnace to press and drawing tool, (3)  plastic hot forming (4) quenching in...