The centrepiece is a standard electric lift truck, which is capable of precise manoeuvring and positioning thanks to its electric steering. Its lifting unit also makes mould changing possible on machines of different sizes. At the same time, the moulds can also be put into storage on vertically-arranged shelves. For this purpose, electronics provide for smooth and precise lifting and lowering movements.
However, the universal electric lift truck first becomes a tailor-made solution for mould changing on injection moulding machines with the addition of a separate attachment. This is permanently mounted on the lift truck and consists of two vertically-arranged roller conveyors. In comparison with the customary horizontal systems, two moulds can be accommodated simultaneously thanks to the double-decker arrangement, without increasing the space requirement for manoeuvring. Thus, the new mould can be brought to the injection moulding machine without interrupting production. The mould change can be performed quickly, without renewed manoeuvring. Furthermore, the old mould can be put back into storage during the heating phase of the new mould. Mould changes can be optimally organised and planned. The integration of additional processes for the optimisation of mould changing is also easily achievable, such as mould heating via a separate preheating station, for example.
Both roller conveyors are equipped with guide strips, in order to laterally align and secure the mould on the roller conveyor during the transfer. The moulds are prevented from falling during transport by means of a front locking mechanism.
A swivel device allows the roller conveyors to be moved into the required position for the transfer, which facilitates manoeuvring of the mould-changing vehicle. Thus, mould changing is also possible in the most confined of spaces and is, in addition, faster, safer and ultimately more efficient. Conversions to the injection moulding machines for improvement of access are not necessary.
The roller conveyors are additionally equipped with a laser pointer for the purpose of horizontal positioning. When the correct transfer height is reached, this can be easily read off by means of suitable markings on the injection moulding machines or on the mould shelves.
As, in the case of horizontal mould changing, a distance to the mould installation area on the injection moulding machine must be bridged, each roller conveyor is fully extendable via a guide unit. This guide unit is adapted to ARBURG’s mechanical rapid-clamping system. In this way, the moulds can be easily pushed from the roller conveyor into the injection moulding machine and can be secured in a few minutes via the rapid-clamping system. For this purpose, indexing the central position of the nozzle and mould clamping are performed by means of four permanently-installed clamping bars.
Standardisation of the clamping platens is generally required for working with the rapid-clamping system. In comparison with conventional mould changing, mould change times and thus machine downtimes can be significantly reduced.
The use of a mould-changing vehicle is appropriate, if no overhead crane or slinging crane is available at the installation location of the injection moulding machine. Thus, it is possible to dispense with the potentially expensive investment and maintenance costs for such fixed production facilities. The simple, intuitive and functional operation of the mould-changing vehicle in conjunction with the ARBURG rapid clamping system, makes mould changing economical, ergonomic, flexible and safe. “Our experience has shown that we can save up to twenty minutes during a mould change,” said Jürgen Schray, Department Manager for Applications Technology at ARBURG.