The new Renk COPE Drive for Loesche mills

On August 18, 2015, and together with mill manufacturer Loesche, Renk presented the new COPE Drive for Loesche mills to an international audience of cement industry experts gathered in Augsburg. We interviewed Florian Hofbauer, Executive Board member of Renk AG, about the new drive system and its advantages.

HOFBAUER: Certain customers had already been introduced to the new concept back in 2013 and 2014. Then in September 2014 on the occasion of an international symposium held by Loesche we addressed a wider public for the first time. Since then we have attended a number of fairs and congresses at which we advertised and presented COPE. Up to now, everyone has been impressed by the compactness and the much extended availability. Because of this extended availability, productivity rises and the initial extra costs are recouped within about one production year – on large plants even faster. Those customers that so far have opted for COPE Drive use it in markets where cement prices are sound, capacity utilization is high and so availability is all the more important. We shouldn’t overlook, moreover, that compared with all other conceivable drives, COPE saves the foundation costs and makes work on the plant more agreeable and quicker because it is so compact. So anything that initially seems to take the form of added costs, very quickly turns into a profitable advantage.

HOFBAUER: It is possible for existing Loesche mills to be retrofitted since the height and diameter of COPE Drives match those of conventional ones. However, the difference in the electrics is so funda­mental that any changeover only makes sense if an investment in the performance part of the plant is pending. A COPE retrofit is an attractive proposition especially where there is a need for higher performance since for the same space COPE can deliver some 20 percent more torque.

HOFBAUER: COPE 2 can transmit 4 to 6.5 MW, COPE 3 from 5.5 to 9.8 MW, and COPE 4 transmits 13 MW. Depending on the rating, six to eight motors are fitted and the planetary stage is adapted to accommodate the required torque. Right now, nothing more is planned but possibly at some later date there might even be a COPE 1.

HOFBAUER: First of all, COPE is an ­abbreviation for COmbined Planetary Electric Drive. What also encouraged us to use the name was its literal meaning of “managing,” “getting to grips with” customer needs which is precisely what the product is designed for. The name is short and snappy and makes it easy to remember the product.

HOFBAUER: As already mentioned, COPE is primarily engineered for extended plant availability and this is achieved through redundancy, meaning: if one drive unit or the matching productive part is not available, there still are several possibilities of continuing the operation of the mill. The switch from a high-maintenance slip-ring motor to zero-maintenance squirrel cage motors is another important argument for enhanced availability. The bottom line is around 3 percent higher availability compared with conventional solutions. Under the assumption that the plant is working at its design load, this spells a remarkable gain in productivity. Another aspect, highly appreciated by customers, is the integration of drive and gear unit into a single system and hence the elimination of an interface.

HOFBAUER: So far, customers have not expressed any wishes in this direction. Our portfolio includes two first-class manufacturers.

HOFBAUER: Drive redundancy is certainly the major difference compared with conventional systems. Any damage to power supply lines, motor and high-speed transmission shafts no longer leads to prolonged downtime. In the event of an electric malfunction, the operator simply disconnects the unit and allows the system to continue running. In the event of a mechanical malfunction, a drive can be simply removed within 2 hours. Alternatively, within one and/or two shifts, a drive unit can also be dismantled or replaced. The essential thing is that production continues while the repair work on the components is going on. In all, we gain around 3 percent plant availability.

HOFBAUER: For removing the motors, we include a transfer device in our scope. The time to remove a motor normally lasts one shift. The supplied cover lids allow the opening to be sealed so that production can continue. A decisive factor is that the end-customer can be trained to carry out this work himself without the need for any experts. In this way, it is possible to repair “on the side” gear bearings, a drive pinion or a motor winding – and even at the manufacturer’s plant. The repair time is no longer critical.

HOFBAUER: Success has so far definitely exceeded our expectations. We have sold a number of drives in three countries. This proves we have succeeded in convincing customers that a gain in availability leads to long-term cost advantages and, especially on large drives, helps lower operating risks.

HOFBAUER: The GEARcontrol subsystem, just as the Condition Monitoring System VIB-Monitor which is provided along with COPE, are capable of online maintenance. We are amazed at how quickly the mindset of customers has changed in this respect. Only a few years ago data cables were severed to prevent operating data from being acquired. Nowadays the practice is for stored data to be jointly reviewed at any time and for decisions to be made immediately on any interventions and changes to the driveline. RENK has taken considerable advance measures and created a secure server landscape and the corresponding software packages in order to address these requirements. It is our belief that in future each of the main plant components will have to satisfy the requirements of online maintenance. With the increasing networking of products, product components and their manufacturers, the mechanical engineering industry is likely to see very many new parameters and conditions for which we intend to ready ourselves now. It is particularly in the networking of the gear systems in the cement industry that we identify a paradigm change. Customers are insisting on online support. They are no longer accepting support in the form of a mechanic traveling out to their premises. As machinery makers we are increasingly being involved in operator issues and the response time for identifying operational phenomena is being shortened by several degrees through this networking. This is a strong industrial trend which forward-looking manufacturers cannot ignore. In fact, an online condition monitoring system ranks nowadays as a standard feature on machines claiming to offer a high degree of availability.

HOFBAUER: As already mentioned, GEARcontrol is a subsystem that relieves the plant planner of complex control and interlocking tasks on COPE. The contractor no longer has to compile and test programs that are possibly faulty. The entire system try-out is done on our test rig and this results in an appreciable shortening of the commissioning time. So, GEARcontrol is a S7-based control system whereas VIB-Monitor is a CMS system that expressly integrates torque measurement. In other words, it not only records the condition of the gear unit, it also warns of any impermissible excessive torque level and allows early intervention in the grinding parameters before any damage can arise at all. With the specific server architecture, we are able to draw attention to problems easily and quickly. Both systems therefore aim at achieving lasting machine availability.