ARBURG’s injection molding machines are renowned for their well tried and tested modularity. When it comes to the ALLROUNDER ALLDRIVE (A) series, the principle of modularity also applies to the drives.
The ALLROUNDER A offers the choice of combining the electric main axes with either electric or hydraulic auxiliary axes, depending on which solution is best suited to any specific application.
The first example of the electric ALLDRIVE series is the ALLROUNDER 420 A 800-400. It has an 800 kN clamping force, 420 x 420 mm distance between tie bars, 400 series injection unit, screw diameters of 35, 40 and 45 mm as well as electric main axes and also an electrically driven five-point toggle system to provide the highest degree of positional accuracy.
Following the successful introduction of the first ALLDRIVE machine, the series was expanded through modular drive technology to include larger clamping forces. As a result, at Fakuma 2003, which is being held from October 14 to 18 in Friedrichshafen/ Germany, the ALLROUNDER 420 A will for the first time be accompanied by its big brother, the ALLROUNDER 520 A with a clamping force of 1,600 kN.
The Good injection molding machine A concept
The main functions of the injection molding machine – opening and closing moulds, injection and dosing – have been designed with electric drives as the basic structure. The other movements such as ejection and moving the nozzle and mould functions can either be electric or hydraulic, depending on the operating requirements.
The movement of the mould closing operation is initiated by rotation of the servomotor to the five-point toggle system via a threaded spindle. This has been specially configured to the dynamic behaviour of the electronic drive.
The injection and dosing movements are converted with high torque via a gear position and a threaded pinion. To operate the movements with optimised use of time and low maintenance, the spindles are equipped with a special cool lubrication system. This ensures a high level of efficiency with low service costs and the longest possible service life.
The machine series are modular in design due to the choice of auxiliary axes with electric or hydraulic drive. In this way, for example, the eject function can be carried out electrically, extremely accurately and dynamically with a spindle, or it can be carried out conventionally (‘softly’) with a hydraulic cylinder.
The nozzle advance movement, which in essence has a contact force applying function for most applications, is mostly with hydraulics or it can also be carried out electrically.
In ARBURG’s view it is very important that core pulls and specific special movements on the plastic mold, which have previously been integrated hydraulically, continue to be optimally operated with hydraulics in the future. For this reason, a special energy-saving small-accumulator hydraulic system has been developed for the optional hydraulic auxiliary functions on the machine, which can be assembled and dismantled on a modular basis.
The basic structure of the electric axes ensures that they are highly dynamic and location-and position-regulated. This produces a reproducible, pin-point procedural sequence. This is mainly used for application with absolute and relative positioning accuracy for the mould and ejection movements.
In this way, for example, stroke-dependent functions such as mould positions in connection with core pull, or final positions when unscrewing, can be achieved extremely accurately.
As all stroke positions are measured absolutely, it is not necessary to carry out a reference movement or set them to a reference point.
On the injection side, the positioning accuracy and the acceleration in conjunction with the position-regulated screw movement can lead to additional accuracy with the injection molded parts. During dosage, the effect of the electric drive can be seen in the accuracy and in the energy requirement.
When viewed on an individual basis, the options and potential for the improvement described, in conjunction with the well-tried and tested SELOGICA control system, lead to added value in relation to parts production.
The opportunity to operate individual cycle stages simultaneously adds even more importance to the programming of the SELOGICA control system. The appropriate cycle symbols with their comprehensive logistic links are extremely clear and can be used to optimise the procedures.
The synergistic effects of the ALLROUNDER A
During the development of the ALLROUNDER 420 A a great deal of importance was placed on the synthesis between the most up-to-date drive technology and tried and tested injection moulding technology.
In this way the design of the clamping areas ensures continued use of existing moulds. Furthermore, the daily operational practice is taken into account owing to the modular nature and the option of connecting hydraulic core pulls onto the plastic molds.
Flexibility through modular construction
The concept of electrically driven main axes as the basis and the option of freely combinable electrically or hydraulically driven auxiliary axes integrates the advantages of both systems.
The machines have sufficient hydraulic power at their disposal precisely where it is needed, and they have the highest level of electro-mechanical accuracy coupled with economic energy consumption wherever feasible for the production task.
This means that the ALLROUNDER A machines also represent extremely flexible production systems, which always allow the machines to be equipped within an optimum cost/benefit framework, while at the same time precisely adapting them to the prevailing production requirements.