Cast or forged?
On early aluminum extrusion presses, many important components (front and back crossbars, the main rams, containers) cast from cast iron or steel. Currently, most of these components are made of forged steel. Forged steel is much easier and, the main thing, reliable control for various defects, and so the provider can confidently guarantee their quality. Experienced manufacturers of new presses will not make machining forgings without a certificate of completion by it of complex ultrasonic and magnetic testing for defects. components design quality of the press necessarily supported by complex calculations, based, usually, on the finite element method.
The thickness of the front rail
The front cross-member media should be as large as practicable. In order to minimize the deflection of the matrix, the rigidity of the front rail must be such, to ensure its deflection at maximum load of not more than 0,25-0,40 mm.
Four columns connect the front and rear crossmember. Their fatigue failure was common for presses early designs. At the present time it is practically impossible due to the installation of the special sleeves and pre-loading of the entire length.
The cycle of idling
Losses from idling media are the main factor in its performance. In recent years, this cycle is greatly reduced thanks to the computer control, improvement of hydraulic systems, shift to designs of presses with a short stroke and in front-loading, as well as other innovations.
presses Suppliers, of course, always declare the shortest cycles of idling. However, it is very important to always use the same definition of this "no-load", when you compare them to the various presses. Different vendors may or may not include such as a decompression process steps, precipitate preform and air outlet. It is best to request a chart of idling, where all its components will be displayed in the Timeline.
The hydraulic system requires the consideration of many issues.
It is good to, if hydraulic equipment received from an acquaintance supplier, which already have experience, including, maintenance of equipment and spare parts. The best thing, to spare parts are common with existing presses.
It is important to know clearly, what responsibility assumes provider for maintenance of equipment after installation, and, if necessary, staff training. The supplier of the press should be ready to take into account your preferences (if any) for the supplier of hydraulic equipment. This preferred supplier can be useful in the preparation of the technical requirements for the hydraulic system for the new press.
The number of main pumps
It is necessary to consider the possibility of increasing the number of the main pumps to improve performance and reduce the duration of idling.
The pumps can be placed on the oil tank above the press, on the floor of the press, in a separate pit or even a separate room. Their location affects the noise level, serviceability and efficiency of the hydraulic system.
Oil filters and cooling oil
Proper filtering of the oil is critical to the life and normal operation of the hydraulic system. It must be ensured, that filters and heat exchanger design, and temperature control system corresponds to the actual climatic and other conditions of your plant.
Pipes and accessories
You need to consider the types and location of pipelines, valves and other auxiliary equipment in order, to reduce water hammer in the system and leakage of oil.
Automated control of the press
All modern presses are controlled by automated control systems based on programmable logic controllers (PLC). However, it is useful to ask , what parameters are included in the control circuit of your new press.
Will this Siemens or someone else - have to deal with supplier, who know your specialists and will provide you with technical support.
Features and Integration
Today's automated control system can be integrated into the computer system of the enterprise with the collection and storage of data, and even the acceptance of orders in real time. The capabilities of these systems is enormous and continues to grow. We need to make, that their potential will really give a new press any advantages.
Special displays can report potential problems before, they happen. for instance, on some new presses allow constant measurements of the alignment state (alignment) of the container relative to the ram. Remote Display Network allows you to monitor the status of the press and to report deviations from the normal operation. With the help of such systems, it is possible to diagnose the press even from another hemisphere of the globe!
container alignment system
Most modern presses used container alignment system, which can be put on the outside of the frame press. These systems allow the alignment axis of the container in the vertical and horizontal planes,.
heating and cooling the container
new press, especially large sizes, differentially heating the container offer several zones, as well as control the temperature of many points of measurement. It is believed, it is reasonable to divide the container into the lower and upper zones. The thing is, that the upper part has a tendency to heat up more than, lower than. Some providers also offer container, which can be cooled, to reduce the temperature, when it exceeds the set limit.
type the die
There are mainly two types of matrix holders used:
- rotary (rotary) and
- a longitudinal-transverse matrix replacement.
Here are the key selection considerations of available space to accommodate.
Type blanks loader
For conventional presses loader is well suited as a carriage, which delivers the workpiece (solid or split) to the center line of the press. For compact or short-running presses applied load from the top and / or robotic loader.
The mechanism of removal of the discard
Separation mechanism of the discard should include a pneumatic chipper for quick removal of the cut of the discard.
Replacement of the container and ram
When using more than one billet diameter, provide the design for quick change of the container and ram.
Pressing without venting
The container is kept open during the precipitation workpiece to eliminate or minimize the length of the air discharge cycle.
locking the matrix
clamping matrix in the horizontal and vertical directions at the time of shearing press residue, to provide a uniform and smooth cutting surface.
Source: Al Kennedy – Seven Steps for Selecting An Extrusion Press , ET2008