All deep-drawing dies need a holding force to be able to draw without creating creases and wrinkles. This retention force can be achieved by the use of double-acting presses (although such products are now rarely used and widely discontinued) or by pressure cylinder systems incorporated into the die or by cushions in the bed.
All deep-drawing dies need a holding force to be able to draw without creating creases and wrinkles. This retention force can be achieved by the use of double-acting presses (although such products are now rarely used and widely discontinued) or by pressure cylinder systems incorporated into the die or by cushions in the bed. Initially, the cushions in the bed were pneumatic, but the necessary technological evolution helped us to develop the hydraulic bed cushion back in 1990, and the servo-mechanical cushion in 2017.
Although we can still manufacture double-acting presses and pneumatic cushions for drawing, these are rarely used and, thus, are not listed in our product range.
TECHNICAL SPECIFICATIONS
Hydraulic Cushion
The main advantages of the hydraulic cushion over air cushions or pressure cylinders are as follows:
Different programmable forces can be exerted during drawing by controlling the retention of the material in an appropriate way.
The option of controlled descent or pre-acceleration, in order to reduce the sudden shock that occurs when the slide hits the cushion and to avoid vibrations that are harmful to both the part and the installation.
The option to lock the cushion (either in its PMI or during ascent) to improve the quality of the piece and aid picking-up the piece by the automation.
Damping at the end of the upward stroke of the cushion to avoid hard stopping of the cushion and, thus, vibrations.
In the following picture you can see a whole working cycle and the nine possible phases of the cushion.
Keep the predefined position.
Pre-acceleration.
Drawing.
Standby.
Pick-up lock 1. This pickup could be a lockage in the PMI of the cushion.
Ascent at Speed 1.
Pick-up lock 2. For example, for the pick-up of the part by the automaticon.
Ascent at Speed 2.
Damping.
All these variables are entered via the HMI, obtaining different possible configurations of the cushion operation.
HYDRAULIC CUSHION ENERGY EFFICIENCY SOLUTIONS
One of the aspects of the hydraulic cushion that can be improved is the reduction of energy consumption.
Taking the standard hydraulic cushion as a reference, we have designed several solutions to reduce energy consumption. One of them, based on variable flow motor-pumps, reduces consumption via its self-adjusting control which allows the required flow to be reduced, adapting to the actual needs of each cycle. The second of these, the High-Low Pressure concept, is a solution designed for the current drawing and ascent process, in which the installation is sized according to the needs. The last solution is based on the previous idea of High-Low pressure and adds a servo-pump system to regenerate most of the energy consumed during the drawing process, returning the energy consumed normally during oil flow to the buffers in a manner controllable by the network.
