2010 Full-Line Drill Catalog - Desanto

Machining technologyBoth findings (spray pattern and reaction time) show theconical shank end and the shank end with labyrinth seal tobe superior to those with plain shank end. Subsequently,only the conical shank end and the shank end with labyrinthseal were deemed suitable for further examination andoptimisation.Because a vector analysis is carried out for the flow, itis possible to analyse the flow pattern according to thedirection of flow. Hereby, the speed vectors are examinedfor forward and reverse flow. Any turbulence formationhas a forward and reverse flow. Often, turbulence occursin dead areas. At this point totally opposing statements canbe made for single and two coolant duct systems.A: Narrow slot withrounded baseWith the assistance of aCFD analysis, the formand size of the connectionslot at the shank end wereexamined. The pictureon the left shows theflow profile within theconnection shank end –adjustment screw for aconical shank end. Variousslot forms were analysed.B: Wide slot withrounded baseWhilst dead areas in single coolant duct systems lead themedium to be deposited on the wall and separating thanksto the flow speed within the turbulence, dead areas in twocoolant duct systems are areas requiring to be filled beforethe medium can continue. Based on the produced flowpatterns, conical shank end B with wide connection slot androunded base proved to be the optimal solution.An analysis of the two requirements “simple handling” and“cost-effective production” painted a similar picture. Thefollowing table shows the respective evaluation, wherebythe data refers to the shank end and the correspondingscrew. Relevant features for process reliability, such as“minimal dead areas” and being “leakproof” providecriteria for excluding the two versions with plain shankends. Subsequently, the most favoured shank end is theone with a conical end and a wide slot with rounded base.TechnicalC: Wide slot with roundconvexbaseD: Wide slot with convexbaseSpray patterns were also produced for the above slot forms,showing a tendency to solution B. However, the variationswere marginal but the CFD analysis showed a clearerpicture.Shank end Handling Cost-effective production Minimal dead areasgeom. analysisLeak-proofPlain w/o slot ++ ++ - -Plain w. sickle-shaped slot ++ + - -Conical with slot ++ + + ++Recessed end withlabyrinth seal - - ++ ++++ = very good properties, + = good properties, - = poor properties312