Deep hole drilling processes for high-alloyed materials are characterised by worn guide pads and chatter vibrations. In order to increase feed rates, process stability and bore quality in STS deep ...hole drilling, various investigations were carried out with adjustments to the tool. First, a new process chain for the production of tribologically optimised guide pads and their effects on the guide pad shape is described in detail. The results of these studies show that the shape change in the area of the axial run-in chamfer through a micro finishing process leads to a better bore hole quality. Furthermore, the influence of guide pad coating and cooling lubricant on the deep hole drilling process was investigated. In addition, the machining of the austenitic steel AISI 304 is analysed by using a conventional steel boring bar and an innovative carbon fibre reinforced plastic (CFRP)-boring bar. While the conventional drill tube oscillates with different eigenfrequencies, the CFRP-boring bar damps chatter vibrations of the drill head and stabilises the process. Even at higher feed rates up to
f
= 0.3 mm, it is possible to machine austenitic, difficult-to-cut-materials with significantly reduced vibrations.
The existing production methods for manufacturing of internal threads are suitable for producing detachable, high-strength joints in lightweight materials. Depending on the technology applied, there ...are process-related variations in the thread quality. Especially in the context of mass production of aluminum components, high productivity and quality are to be obtained. Innovative tapping technologies provide advanced process concepts, which allow minimized production times. In this study, the technical properties of internal threads are investigated in relation to the manufacturing process. By applying scientific valuation methods, the analysis of different tapping technologies for aluminum casting materials is achieved.
By using modern technologies to produce detachable joints in lightweight components, it is possible to reduce material consumption and manufacturing times. By front face flow drilling of lightweight ...cast materials, expanded bore walls are formed into thin-walled profiles, which are used as core holes for internal threads. The flow drilling process has to be adapted to the specific properties of the regarded materials AZ91 and AlSi10Mg. Thus, enhanced adjustments make it possible to increase the bore qualities significantly. Particularly in order to improve the roundness of the holes, the influence of decreased feed rates on the shape of the flow-drilled holes is analysed. Furthermore, this paper deals with the influence of the process temperature during flow drilling. By varying the predrilling diameter as well as the peripheral speed, the friction between the tool and the workpiece can be significantly influenced. This directly affects the thermally induced formability of the lightweight alloys. In order to produce high strength threads, cold forming is used instead of conventional tapping. In particular, in the context of the adapted flow drilling strategies, the surface qualities and the threads profiles are investigated in detail. Finally, continuous load increase tests were conducted to evaluate the fatigue properties of the formed internal threads using various strategies.
In face flow drilling of lightweight cast materials, the heat transfer makes a significant contribution to forming ability. Especially during processing of the magnesium alloy AZ91 and the aluminum ...alloy AlSi10Mg, microstructural mechanisms lead to in high rates of deformation, resulting in undesirable hardening of the marginal zones. During the subsequent thread forming process, the resulting microstructure leads to an inadequate forming of the internal thread. In order to improve the geometrical and mechanical thread quality, the influences of the initial tool temperatures and the heat input induced during the forming processes are analyzed within this paper.
High interstitial austenitic stainless CrMn steels are characterised by significantly increased work hardening ability and strength compared with conventional CrNi austenites, yet maintaining very ...high ductility and toughness. The machining of high interstitial CrMnCN steels is challenging in terms of process stability and economic efficiency. In this context, unfavourable chip forms, high thermomechanical loads and the superposition of different wear mechanisms in particular lead to challenges in turning operations. In the following article, different lubricant strategies are analysed for machining of CrMnN and CrMnCN austenitic stainless steels regarding chip form, mechanical tool loads and wear. Furthermore, the workpiece properties are considered with regard to surface roughness and microstructural changes.
High interstitial austenitic stainless CrMn steels are characterised by significantly increased work hardening ability and strength compared with conventional CrNi austenites, yet maintaining very ...high ductility and toughness. The machining of high interstitial CrMnCN steels is challenging in terms of process stability and economic efficiency. In this context, unfavourable chip forms, high thermomechanical loads and the superposition of different wear mechanisms in particular lead to challenges in turning operations. In the following article, different lubricant strategies are analysed for machining of CrMnN and CrMnCN austenitic stainless steels regarding chip form, mechanical tool loads and wear. Furthermore, the workpiece properties are considered with regard to surface roughness and microstructural changes. Keywords High-strength materials; stainless austenitic steels; cooling lubricants; corrosion resistance; Interstitials; work hardening; turning Nichtrostende, austenitische CrMn-Stahle zeichnen sich durch ein deutlich hoheres Kaltverfestigungsvermogen und sowie eine gesteigerte Festigkeit im Vergleich zu konventionellen CrNi-Austeniten aus, wobei sie eine sehr hohe Duktilitat und Zahigkeit aufweisen. Die Zerspanung von CrMnCN-Stahlen gestaltet sich in Bezug auf Prozessstabilitat und Wirtschaftlichkeit dabei als sehr herausfordernd. In diesem Zusammenhang fuhren insbesondere ungunstige Spanformen, hohe thermomechanische Belastungen und die Uberlagerung verschiedener Verschleissmechanismen zu Herausforderungen bei der Drehbearbeitung. Nachfolgend werden zwei unterschiedliche Schmierstoffstrategien fur die Zerspanung von austenitischen CrMnN--und CrMnCNEdelstahlen hinsichtlich Spanform, mechanischer Werkzeugbelastung und Verschleiss analysiert. Daruber hinaus werden die Werkstuckeigenschaften im Hinblick auf Oberflachenrauheit und Gefugeveranderungen betrachtet. Schlusselworter Hochfeste Werkstoffe; Nichtrostender, austenitischer Stahl; Kuhlschmierstoffe; Korrosionsbestandigkeit; Interstitielle Elemente; Kaltverfestigung; Drehbearbeitung
The aim of this study is to evaluate impact of varying core hole diameters on resulting thread quality for helical thread forming. Regarding to common applications in mass production of engine ...casings in automotive industy, the experiments were performed in AlSi10MnMg cast alloy and thread size M6. Regarding the forming process by analysis of mechanical tool loads measured, various characteristics and microstructure of flank profile, it has been found out that the core diameter has a significant influence on thread quality resulted. It points out that for increased pre-drilling diameters, lower tool loads occur while flanks are formed incomplete.
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