As part of the EDAG group's innovative EDAG Light Car - Open Source project, Honsel Group contracted HEATform to form a super-light and strong joint for a space frame A-pillar/Header/Roof Rail connection. Node construction theory is enabled cost effectively by using HEATform's unique gas pressure warm forming methods on a chamber extruded 6082 Aluminum blank. This near net shape component is optimized in wall thickness and geometry so that connecting extrusions can simply be press fit and welded to create the final structural joint. HEATforming was chosen for this project due to its capability for high forming ratios, near net shape complex geometry and alloy flexibility at competitive cost structure.
Compared to Hydroforming, HEATforming does not require the use of expensive alloys as the starting tube. It is even flexible enough to use hot extruded tubes. HEATforming also maintains and provides desired mechanical properties, like tensile and yield strength. This alloy selection freedom, expanded design envelope, and cost efficiency is leading to new approaches in the engineering and manufacturing of space frames and vehicle design.
This example part was produced as a double part (left-right pair) using a pre-bent, chamber extruded aluminum oval tube in AL 6082 alloy. The high forming degrees illustrated are enabled by the HEATform process.
The parts are cut and machined resulting in a left/right car set for shipping to the end customer.
HEATforming was selected as the method of choice for volume production of this space frame component instead of the alternative of a multi-piece sheet aluminum fabrication with a steel inner reinforcement. The resulting HEATformed part has excellent crash performance without sacrificing weight or section size.
With the developed heat treatment process for this application, the required material strength properties of Rm >340 Mpa and elongation of A5>10% have been achieved.
HEATforming™s unique processing is friendly to material grain structure, allowing great flexibility in tailoring material properties to meet performance needs.
In this project, various Geometries and Alloys (AL 7108 and AL 7020) were examined. The blank used was a chamber extruded tube with a wall thickness of 5,5mm. This tube was chosen to allow prebending in the cold condition. Avoiding warm pre bending minimizes the cost of blank preparation for high strength alloys. The pre bent blank must simply fit into the die, and this allowance for rough pre-bending is an advantage of the HEATform process.
This single piece solution replaces a multi part construction standard. Typically, the part is constructed from 3 pieces: Two side tubes are extruded and machined; a top tube is bent or forged, and then the parts are welded together in a welding fixture.
This product is manufactured and assembled into the 3 liter diesel engine in the current Audi Q7 and Volkswagen Touareg.
This frame member concept study demonstrated the feasibility of extreme engineering design geometry coupled with a specific aluminum alloy. HEATforming was combined with a cold preforming stage to form this part.
This geometry was formed in a single forming step using AL 6061 alloy.
Application: Air Spring Piston for Auto Damper
Example parts of a family of air springs used in various vehicles. Starting tube is an impact extruded body Al 6082.