Michał Gdula

Zastosowanie systemu Omative w obróbce łopatki turbiny ze stopu Inconel 718

The modern aviation industry is increasingly demanding its components, while striving for maximum efficiency and maximum profit. New construction solutions make it necessary to use special materials such as heatresistant super alloys. These are alloys based on nickel, cobalt or iron. Of these, one of the best properties is Inconel 718 [1, 2]. The advantages of this alloy are particularly important in those engine points that are subjected to the largest loads. The turbine blades work in the most difficult temperature and load conditions. The blade end speed reaches 390 m/s, the gas temperature is even 1200 °C and their speed is 600 m/s. The turbine blade material, in addition to high strength, must be characterized by high heat resistance, high temperature creep resistance, corrosion and oxidation resistance and high hardness. Density of the alloy, which affects the weight of the engine, is also important in generating centrifugal forces [3, 4]. Inconel 718 is one of the hardest materials to work on. Blade locks are currently being successfully developed in the Creep-Feed Grinding (CFG) process. This method allows for efficient machining of elements made of super alloys and other hard-working materials. It allows the parts to be polished after heat treatment and ensures high surface quality [5]. On the other hand, in the case of free surfaces of the blades, the method of their execution is simultaneous process of five-axes milling. Due to the complexity of this machining, the presence of high milling strength components and the high cost of the workpiece and tooling, it is legitimate to use a system that monitors the correctness of the cutting process. They are based on the measurement of selected physical quantities, such as: cutting force, vibration, power and engine torque, sound emission or coolant flow. Measured signals (after processing) serve to obtain process measures

Cutting layer and cutting forces in a 5-axis milling of sculptured surfaces using the toroidal cutter

The purpose of this article was to evaluate the significance of the influence of fiveaxis orientation parameters of a toroidal cutter axis and the geometrical parameters of the machined sculptured surface on the intersection of the cut layer in a 5-axis machining. An impact assessment was performed by simulating concave-convex and convex-concave surfaces using a discrete method of direct transformation in a CAD environment. It was shown that only the radius of curvature of the surface in the feed direction and the angle of the tool axis affected the change in the intersection of the cutting layer. Subsequently, experimental tests were conducted that aimed at determining the mathematical models of the influence of these important parameters on the components of the cutting force. The object of the experimental studies was a convex and concave surface of a turbine blade of Inconel 718 alloy. The R300-016B20L-08L Sandvik Coromant toroid cutter was used for the tests. Based on the results of the study it was found that the lead angle in the machining of the convex surface and concave turbine blade should be continuously varied with the change of radius of curvature in the direction of the machined surface profile.

The influence of the cutting edge shape on high performance cutting

Purpose The purpose of this paper is to determine the influence of the shape of a cutting edge on high-performance milling high-performance cutting. The main purpose of the test was to determine the possibility of increasing the efficiency of machining AlZn5.5CuMg alloy, which is used mainly for the thin-walled structural aerospace components. Design/methodology/approach In all, eight cutters for machining aluminum alloys with different shape of the cutting edge (1 – continuous, 4 – interrupted, 3 – wavy) were tested. The influence of different shapes of a cutting edge on cutting force components and vibration amplitude was analyzed. Furthermore, the impact of a chip breaker on the form of a chip was determined. Findings The conducted test shows that using discontinuous shapes of a cutting edge has impact on the reduction of the cutting force components and, in most cases, on the increase of vibration amplitude. Moreover, using a chip breaker caused significant chip dispersion. The optimal shape of a cutting edge for cutting AlZn5.5CuMg alloy is fine wavy shape. Practical implications Potential practical application of the research is high-performance milling of AlZn5.5CuMg alloy, for example, production of thin-walled aerospace structural components. Originality/value Different shapes of a cutting edge during high-performance milling of aluminum alloy were tested. The influence of tested geometries on HPC process was determined. The most favourable shape of a cutting edge for high-performance cutting of AlZn5.5CuMg alloy was determined.

Five-axis milling of sculptured surfaces of the turbine blade

Purpose The purpose of this paper is to determine the influence of a toroidal cutter axis orientation and a variable radius of curvature of the machined contour of sculptured surface on the five-axes milling process. Simulation and experimental research performed in this work are aimed to determine the relationship between the parameters of five-axes milling process and the shape and dimensional accuracy of curved outline of Inconel 718 alloy workpiece. Design/methodology/approach A subject of research are sculptured surfaces of the turbine blade. Simulation research was performed using the method of direct mapping tools in the CAD environment. The machining research was carried out with the use of multi-axis machining center DMU 100 monoBLOCK DMG, equipped with rotating dynamometer to measure the components of the cutting force. To control the shape and dimensional accuracy, the coordinate measuring machine ZEISS ACCURA II was used. Findings In this paper, the effect of the toroidal cutter axis orientation and the variable radius of curvature of the machined contour on the parameters of five-axes milling process and the accuracy of the sculptured surfaces was determined. Practical implications Five-axes milling with the use of a toroidal cutter is found in the aviation industry, where sculptured surfaces of the turbine blades are machined. The results of the research allow more precise planning of five-axes milling and increase of the turbine blades accuracy. Originality/value This paper significantly complements the current state of knowledge in the field of five-axes milling of turbine blades in terms of their accuracy.