Forming High Strength Steel in Automotive Applications

Repetitive Stamp-and-Hold Servo Press Slide Movement Eliminates Spring Back of an automotive AHTSS Beam.

The example to the right is an automotive beam made of Advanced High Tensile Strength Steel (AHTSS).
In the left-side picture, the beam has been stamped in one stroke using a traditional mechanical press with an eccentric shaft, crankshaft, or eccentric gear drive.  You will see that the sides of the beam have noticeably flared-out and not held shape.  This is due to the material's high tensile strength.  In order to control the material and eliminate the springback using a traditional mechanical press, you would need to use two presses and a transfer; one to do the first stroke and the other to restrike to take the spring back out of it. You could also restrike the part with the same press.  Obviously, these two choices involve more resources at slower production rates.

In the same example, the picture on the right side is the same part that has been formed using one hit on a servo press.  With the ability to program the press's slide position, speed, and dwell, the resulting slide motion profile (to the left) allows you to bring the slide down at a greater speed, then slow down as it reaches BDC.  By slowing the slide down, there is better stress relief of the material, allowing it to steadily flow into shape. The slide then comes up above BDC to allow the material to springback slightly before the slide comes back down to form the final shape.  You can see an example of this by watching the following video:
video
For more information on this example and other servo press advantages, contact Randy Kish at randy@seyiamerica.com or call 1-931-455-4876.

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