Energy chains for an XXL 3D water jet cutting machine

Ridder is known as a water jet cutting specialist: Water jets deliver an almost unimaginable pressure (3,800 bar) to separate metals and plastics. The advantages of the "cold" process are that no harmful emissions develop during cutting and that the cutting surface is given a perfect finish even without rework. And there is no distortion in the cutting.
Ridder originally developed systems with a cutting table for 2D machining. Later, Waricut-series 3D linear robot systems that moved on vertical axes were added. But this is the largest machine that Ridder has put into operation to date:
The Anssems Group, based in the Netherlands, has ordered a five-axis water jet cutting machine with a cutting volume of 32,050 x 5,050 x 1,900mm (X/Y/Z axis) for horse trailer production. Two bridges, each with a 3D cutting head, move on 32-metre linear robot axes. The machine is divided into four cabins so that the two cutting heads can each process one component while the other two cabins are being changed over. This ensures continuous system utilisation. Each cutting head can move to all four cabins, ensuring high flexibility and availability.
The water jet cutting machine's task in production will be to process the glass-fibre reinforced plastic superstructures that were laminated and formed in the previous work steps and make door cut-outs in the horse trailer, for instance.It achieves very high precision. While the systems usually work with an accuracy of ≤ ± 20µm per metre, the long travels mean that this system has an accuracy of 50µm. The Ridder design engineers had to solve the problem of supplying the cutting heads with energy, signals, compressed air, and (of course) water. The high linear axis maximum travel speeds (20m/min) also had to be taken into account. But the biggest problem was the long travel. Given these lengths, the chain's upper run is especially likely to simply rest on the lower run (the gliding energy chain principle). This system could not thus glide for two reasons: The heavy filling and long travel distance would have generated too much friction. And the high-pressure line for the water supply requires a larger bend radius, so the "chain on chain" principle was out of the question.

The designers opted for a solution that has already proven itself in other Ridder systems: A polymer energy chain of the E4.1 series. The energy chain is 100mm wide and 56mm high. In addition to the high-pressure cable with a diameter of 1/4 inch, it also contains the special chainflex energy cables for the 3D cutting head, which are suitable for continuous movement, and the CAN bus cables for communication. A centre crossbar 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 principle of the gliding chain must be abandoned because the swarf can damage the chain parts gliding on top of each other. For these cases, the so-called guidelok system for energy chains was developed, which allows the upper run to be guided independently. It consists of support elements arranged in pairs, in which pivoting roller holders are assembled. When the chain is guided past the carriers, the roller holders pivot 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 strong guidance of the upper run can be ensured with very simple means and few components - and the unsupported length of the energy chain can be increased considerably. As the chain in the guidelok system is guided by rollers, very little push/pull force is required to move it, which 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 program enables the fully automatic processing of the glass-fibre reinforced plastic superstructures. The movable cutting head, which can pivot ± 95° and rotate ± 540°, allows cutting even in areas that are difficult to access. And while the system is working through its program in two cabins, the other two can already be loaded with new components.