Five-axle truck gets second life
The term retrofit is all too often employed as a grateful buzzword to explain sometimes very radical machine overhauls. Or as a synonym for a radical, indiscriminate conversion. What a real retrofit should always entail was demonstrated by the West-Flemish Eurobotics with its beautiful project on a five-axle machine at Agfa-Gevaert.
The retrofit was done on a five-axis milling machine built in 1995, with rotating milling spindle. This machine had never been used intensively, was well maintained and was mechanically still in relatively good condition. About two years ago, however, problems arose with the spindle, so the customer decided to have the obsolete electronics checked as well.
Pascal Demol (Eurobotics): "The existing control box contained quite a bit of obsolete technology, including older Siemens drives and modules from Heidenhain. At the same time, a number of motors, encoders and measuring systems were also in need of replacement. Control manufacturer Heidenhain fully examined the machine and sent a technical report with a set of recommendations and working budget to each of its AIP companies (Acknowledged Integration Partner) in Belgium."
In the end, Eurobotics was awarded the contract. A challenge the company gladly accepted, especially since the machine did not require a complete revamp. This project would entail a very strategic integration of new technology, supported by thorough technical feedback from Heidenhain. Eurobotics prepared the project to the maximum extent in its own workshops, so that the milling machine could remain in operation until the start of the retrofit.
Pascal Demol: "We chose a new keyboard with 24-inch screen to begin with. Although the Heidenhain package provided 19 inches, we managed to convince the customer to choose a screen that also allows you to control an external desktop. Everything was housed nicely in a custom-built enclosure that we built ourselves."
The existing control cabinet was taken in hand: A solid mounting plate was provided where the old modules sat, on which a set of modern contactors, a new PLC and safety PLCs were built. A modified interface connector was used, so that otherwise all existing components, switching systems and wiring could be left unchanged in the cabinet. Thus, the control cabinet remained as uncluttered as before.
The same thing was done identically with the drives. Where previously there was a whole battery of old Siemens drives, a plate was custom made for the power and drive modules, with more room for the heavy wiring of the motors (power part 55kW GEN 3 Heidenhain).
Pascal Demol: "In the control cabinet behind the left door is the plate with new PLC and the safety PLCs. Behind the right door are the new drives. A large part of the original control cabinet, such as a series of contactors and plug-in relays, is no longer used. The reason for this is simple: the old drives were still controlled via contactors."
In the new system, all enable signals are fed into the PLC. The contactors that are still in use are really only for secondary functions such as chip removal, or for relays controlling valves that are separate from the direct machine control. All the crucial stuff is nicely integrated into the two sections that were replaced. Mechanically, Eurobotics encountered few problems, for example, all the flange sizes of the motors were perfectly identical. Only the shaft diameters were larger, so some exceptional turning work had to be done here.
Regardless, the entire project took some time. However, the retrofitted five-axle unit gained a new youth and has been in operation for over a year without any problems.