Discussion following TAPHOLE DESIGN AND EXPERIENCE

摘要

Ian Cameon: When you use the hydraulic drill and you're drilling so very fast, have you encountered any problems with the last 1/2 metre of drilling? Georg Grabietz: No. The point is that we do not make use of the full force because when you first start with a full hydraulic machine you have to get a feeling of what is detrimental or not. So as I mentioned, we have steps of 20 percent. We have for example, a torque of 500 Newton metres and we can drill with 100 or 200 or 300, and we can adjust it. We can step forward, to try to find what is the best one. So BF A was the first one. We had the feeling that hammering was detrimental for the taphole blacks. So we said we only want to drill softly, we don't want to hammer. Advice offered by two suppliers at that time was to use full hydraulic machines. We are very satisfied with it, we drill very fast. The new value is now set to the monitoring system and to have the possibility, because we started a new PC7 system. So we are now able to put parameters on, and we don't allow the casthouse team any deviation from the parameters, only in case of emergency and then they have to report to the engineer on duty. We give them the torque and the feed, all worked out empirically. Now we have three different materials, three different parameters, ad we have fond that everything is running very smoothly. We always have the same amount of mud, the same conditions, and we can see each drill. You can enlarge it on the screen, see all the inclinations of the diagram, distance to time. You see if there is a gas bladder and can discuss it with your supplier of the material. It was nice to also save a lot of material with the water-cooled machine.