Featured Research

from universities, journals, and other organizations

Perfect welds for car bodies

Date:
June 6, 2011
Source:
Fraunhofer-Gesellschaft
Summary:
Surface welding instead of penetration welding, allows a laser to produce a weld that is only visible on one side. But how do you control the laser power to prevent it burning a hole through the sheets of metal? A new camera system analyzes thermal images in real time -- and ensures a perfect weld.

In the new surface welding process the laser produces a perfect seam. Bottom left: Weld seam profi le – the penetration depth is controlled without damaging the bottom surface.
Credit: Image courtesy of Fraunhofer-Gesellschaft

Surface welding instead of penetration welding, allows a laser to produce a weld that is only visible on one side. But how do you control the laser power to prevent it burning a hole through the sheets of metal? A new camera system analyzes thermal images in real time -- and ensures a perfect weld.

As if controlled by an invisible hand, the welding head on the robot's arm races along the sheet metal parts. Where the laser hits, sparks fly and the metal glows red hot. The process lasts just a few seconds. The outer door panel and the door frame are now welded together perfectly. A thin weld seam extends along the join, but it can only be seen on one side. From the other side of the welded car door the join is invisible. This is a perfect weld -- the kind every car manufacturer dreams of, because it could be used anywhere on the car body. Expensive work to hide the seam, such as folding the sheet metal or covering with trim would no longer be necessary.

Research scientists at the Fraunhofer Institute for Physical Measurement Techniques IPM in Freiburg have turned this car makers' dream into reality. 'Controlled partial penetration welding' is how experts refer to the process in which the laser does not burn right through all the sheets of metal -- in contrast to full penetration welding, where a hole briefly forms in the melt pool. Instead, the weld seam is controlled to penetrate the lower sheet without damaging the bottom surface. Up to now, however, it was not possible to precisely control this type of welding and produce a seam that meets the requirements in respect of strength.

"As we do not weld through the sheet, basically we cannot see what we are doing," states Andreas Blug, project manager at Fraunhofer IPM, outlining the problem. But they found the solution using an innovative camera that generates temperature images. This enables the system to recognize how deep the laser has penetrated into the sheets. Where it burns into the metal, causing it to melt, the images show a hot region. If the bottom of the melt pool reaches the gap between the upper and lower sheets, the conduction of heat is interrupted and a cooler point can be seen. This is referred to as the full penetration hole. From the relative frequency of this full penetration hole the system calculates the penetration depth into the lower sheet. A software program then adapts the output of the laser to the specific requirements. "The process is closed loop controlled in real time," Blug explains. An extremely rapid camera system is needed for this -- which is the key to Fraunhofer IPM's innovation. The system is based on cellular neural networks (CNN). A tiny processor is integrated in each pixel. They all work simultaneously and speed up the analysis of the individual images enormously, whereas in conventional image processing systems a few processors process the data consecutively. "In this way the system analyzes up to 14,000 images per second," says Blug. This compares with the usual rate of only 1,000 to 2,000 images per second.

Together with colleagues from the IFSW Institut für Strahlwerkzeuge at Stuttgart University and the Institut für Grundlagen der Elektrotechnik und Elektronik (IEE) at Dresden University of Technology, the Fraunhofer IPM research scientists have now developed a prototype which perfectly controls the surface welding process, offering car makers a further great benefit in comparison with full penetration welding: zinc does not vaporize on the bottom side of the weld. The corrosion problems encountered on galvanized car bodies are therefore a thing of the past.


Story Source:

The above story is based on materials provided by Fraunhofer-Gesellschaft. Note: Materials may be edited for content and length.


Cite This Page:

Fraunhofer-Gesellschaft. "Perfect welds for car bodies." ScienceDaily. ScienceDaily, 6 June 2011. <www.sciencedaily.com/releases/2011/05/110512103944.htm>.
Fraunhofer-Gesellschaft. (2011, June 6). Perfect welds for car bodies. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2011/05/110512103944.htm
Fraunhofer-Gesellschaft. "Perfect welds for car bodies." ScienceDaily. www.sciencedaily.com/releases/2011/05/110512103944.htm (accessed July 22, 2014).

Share This




More Matter & Energy News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Government Approves East Coast Oil Exploration

Government Approves East Coast Oil Exploration

AP (July 18, 2014) — The Obama administration approved the use of sonic cannons to discover deposits under the ocean floor by shooting sound waves 100 times louder than a jet engine through waters shared by endangered whales and turtles. (July 18) Video provided by AP
Powered by NewsLook.com
Sunken German U-Boat Clearly Visible For First Time

Sunken German U-Boat Clearly Visible For First Time

Newsy (July 18, 2014) — The wreckage of the German submarine U-166 has become clearly visible for the first time since it was discovered in 2001. Video provided by Newsy
Powered by NewsLook.com
Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Reuters - US Online Video (July 17, 2014) — President Barak Obama stopped by at a lunch counter in Delaware before making remarks about boosting the nation's infrastructure. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

TheStreet (July 16, 2014) — Oil Futures are bouncing back after tumbling below $100 a barrel for the first time since May yesterday. Jeff Grossman is the president of BRG Brokerage and trades at the NYMEX. Grossman tells TheStreet the Middle East is always a concern for oil traders. Oil prices were pushed down in recent weeks on Libya increasing its production. Supply disruptions in Iraq fading also contributed to prices falling. News from China's economic front showing a growth for the second quarter also calmed fears on its slowdown. Jeff Grossman talks to TheStreet's Susannah Lee on this and more on the Energy Department's Energy Information Administration (EIA) report. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins