Energy chains for an XXL 3D water jet cutting machine

Ridder is known as a specialist in water jet cutting: A jet of water cuts through metals and plastic at an almost unimaginable pressure of 3,800 bar. The "cold" process offers the advantages that no harmful emissions are produced during cutting and that the cut surface has a perfect finish even without post-processing. In addition, no distortion occurs during cutting.
Ridder originally developed systems with a cutting table for 2D machining. Later, 3D gantry systems from the Waricut series travelling on high axes were added. This project, however, is the largest machine ever commissioned by Ridder:
This is because the Dutch Anssems Group has ordered a five-axis waterjet cutting system with a cutting volume of 32050 x 5050 x 1900 mm (x/y/z-axis) for the production of horse trailers. Two bridges, each with a 3D cutting head, move on the 32 metre long portal axes. The system is divided into four cabins so that the two cutting heads can each process one component while the other two cabins are being retooled. This ensures continuous capacity utilisation of the system. The fact that each cutting head can access all four cabins ensures high flexibility and availability.
The task of the water jet cutting system within production will be to process the glass-fibre reinforced plastic superstructures, which were laminated and shaped in the previous work steps, and to cut the door cut-outs into the horse trailers, for example. A very high level of accuracy is achieved in the process. While the systems usually work with an accuracy of ≤ ± 20 µm per metre, this system achieves an accuracy of 50 µm due to the large travel distances. The Ridder designers had to solve the task of supplying the cutting heads with power, signals, compressed air and water. The high maximum travelling speeds of the linear axis of 20 m/min. also had to be taken into account. The biggest problem, however, was the long travel. On these lengths in particular, the upper run of the chain simply rests on the lower run according to the principle of the sliding energy chain. This was not possible with this system for two reasons: due to the heavy filling and the long travel, there would have been too much friction. In addition, the high-pressure pipe for the water supply requires a larger bend radius, so that the principle "chain on chain" was out of the question.

The designers opted for a solution that has already proven itself in other Ridder systems: A polymer energy chain from the E4.1 series. The energy chain is 100 mm wide and 56 mm high. In addition to the high-pressure cable with a diameter of ¼ inch, the special chainflex® energy cables for the 3D cutting head and the CAN bus cable for communication, which are suitable for continuous movement, are also routed through it. A centre bar ensures reliable separation of the high-pressure cable from the electrical cable. In order to keep the two chains as short as possible with a travel of 32 metres, the infeed takes place in the middle of the travel path.
However, a solution also had to be found for the problem of the chain coming off. If swarf can accumulate on the upper side of the lower run, the sliding chain principle has to be abandoned because the swarf can damage the chain parts sliding on top of each other. For these cases, the so-called system guidelok was developed for energy chain , which enables independent guidance of the upper run. It consists of support elements arranged in pairs in which swivelling roller holders are mounted. When the chain is guided past the carriers, the roller holders swivel in and then out again to guide the chain. The upper run thus rests on the roller holder and maintains the distance to the lower run. This principle also has the advantage that the bend radius of the chain can be freely determined: It simply results from the height at which the roller holders are
attached. In this way, a very stable guidance of the upper run can be guaranteed with very simple means and few components - and the unsupported lengths of energy chain can be increased considerably. As the chain in the guidelok system is guided by rollers, very little traction/push force is required to move it - this ensures energy-efficient, smooth running of the chain.
The test results have now also confirmed the performance of the system. When it goes into operation, several fixtures with trailer superstructures are precisely positioned in a cabin, and a 3D CAD/CAM programme enables the fully automatic processing of the glass-fibre reinforced plastic superstructures. The movable cutting head, which can swivel ± 95° and rotate ± 540°, allows cutting even in areas that are difficult to access. And while the system is working through its programme in two cabins, the other two can already be loaded with new components.