Project overview

Project name	Development and commercialization of high-density energy beam-applied one step roll-hemming technology
Supervision institution	Korea Automotive Technology Institute
Participating institution	Kyungki Industrial Co., Ltd

Technology overview

Hemming technology

What is hemming?

• Technology used to fold outer panel flanges along inner panel ends.

Hemming technology

• Domestic: Press hemming technology→ Suitable to mass-production, high-cost of equipment, and difficult to keep molds in the event of discontinued service
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• Overseas: Roll-hemming technology → Suitable to small quantity batch production, low cost of equipment, and very slow production cycle
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The Importance of technical development

A roll hemming technology requires increase of hemming robots and automation of jig system to reduce cycle time and increases the cost of production equipment.

• The necessity of roller hemming system decreases compared to press hemming system.

• Roll hemming cycle time (Reference)

• When manufacturing difficult-to-form aluminum and magnesium car body parts, it is difficult to develop parts owing to poor-quality hemming.
• In case of sheet frame parts, it is difficult to do a hemming work owing to application of super-high strength steel sheets.ets.
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Differentiation of development technology

Features of development technologyy

Conventional technology vs New Technology

Classification	Conventional technology (Press hemming & roll hemming)	New Technology
Quality	– Impossible to do a hemming for difficult-to-form materials.	– Possible to do a hemming for difficult-to-form materials.
Technology	– Implement a hemming process with a multiple hemming step.	– Possible to implement one-step hemming process.
Core technology	– Ordinary hemming technology using press or roller.	– Specialized hemming technology for difficult-to-form materials such as magnesium sheet. – Technology to control sheet temperature in real time by laser output control. – System technology between laser local heat-treatment device and hemming devices – Technology for temperature measurement system using laser coaxial optical system
Strength	– Press hemming: Suitable for mass production – Roll hemming: Relatively simple production system	– Suitable for small quantity batch production, after-market, and tuning market. – Able to do a hemming for difficult-to-form materials. – Reduce cycle time.
Weakness	– Press hemming: Very high cost of equipment – Roll hemming: Long cycle time; not applicable to difficult-to-form parts.	– Require laser heating system.

Patent 1: One-step roller hemming technology

• Application No.: 10-2008-0067010
• Inventor: Kim Dong-Yok, Yu Yong-Mun
• Applicant: Korea Automotive Technology Institute

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※ Consists of horizontal area bending a flange (142) and a perpendicular plane supporting a flange outside (141a)
※ This roller hemming device is constructed to support right and left and top and bottom transmission and rotation.
※ Accordingly, roller shape design is intended to finish a final hemming with one step

Patent 2: Laser local heating roller hemming

• Technology Application No.: 10-2012-0010725
• Inventor: Kim Dong-Yok, Yu Yong-Mun, Han Beom-Seok, Ro Sang-Ho
• Applicant: Korea Automotive Technology Institute

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※ This is a manufacturing method used to combine inner sheet (11) and outside sheet (12) by pressurizing them on a hemming roller (20). It features having heating means on the same body as a hemming roller (20) and bending inner sheet (11) and outside sheet (12) by applying heat to heating point (15) of an outside sheet (12) embracing the edge of an inner sheet (11).

Results of technology development

Project name	Development of laser local heating roll hemming technology (Field-customized development project)
Project period	2011-2012
Project period	2011-2012
Objective	Development of laser local heating roll hemming technology and production of magnesium fender parts
Patent application	One case of patent application for “local-heating applied roller hemming method”td>
Thesis publication	“A study on the change in microstructure of products formed by laser local heating hemming on magnesium sheets,” The Korean Society for Technology of Plasticity and two other publications.

Description of additional development for commercialization

Laser local heating one-step roll hemming process OLP-applied technology

• Review workability through simulation of a robot equipped with developed hemming system.
• OLP input to robot controller and calibration
• Review process validity according to interference among systems and work sequence within automated processes
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Design and produce laser heating one-step roll hemming system for car body production.

• Manufacture laser heating heads for local heating.
• Manufacture real-time temperature measurement devices by using laser head-integrated pyrometers.
• Manufacture laser output control system through real-time temperature measurement.
• Synchronize laser head parts with roller parts.

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Apply laser heating one-step roll hemming technology to door parts and conduct final verification.

• Manufacture hemming jig system for doors
• Apply laser heating one-step roll hemming OLP.
• Implement roll hemming works.
• Analyze the quality of hemming parts for door products.

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