Theoretically Investigation On The Roughness Profile of The Machined Surface After Flank Milling

In this study, the roughness profile of a machined surface obtained via a flank milling process is thoroughly investigated through theoretical modeling and experimental demonstrations. First, the roughness profile of a machined surface generated by a single-tooth end milling cutter along a straight path is considered (without helical angle). The trajectory of a point on the cutting edge is constructed according to the cutting kinematics, and the roughness profile of the flank surface is theoretically extracted from the trajectory. The surface topography is constructed by integrating the roughness profile along the axial direction of the cutter. Based on the constructed roughness profile model, the effects of cutting parameters on the roughness profile are discussed, including those of the cutting speed, radial depth of the cut, and feed rate. In addition, the effects of cutter geometries including the cutter tooth number, tooth spacing angle, and helical angle on the roughness profile and surface topography are discussed. Further, roughness profiles are constructed for cutter feeds along different tool paths, such as round and curved paths. Finally, experiments are conducted to verify the method developed in this study. The results show that the roughness profile obtained from testing matches well with the theoretically modeled profile. Moreover, the methodology for constructing the roughness profile is compared to an existing approach, which shows that the method in this study is significantly faster.

CFD analysis on the oil flow of a gear stage with guide plate

Gearbox housing geometry and oil guide plates strongly influence gearbox oil flow and interaction of oil with machine elements. Guided oil flow can increase gearbox efficiency and improve heat management. Recent research studies have demonstrated the potential of Computational Fluid Dynamics (CFD) simulations to predict the gearbox oil flow and no-load losses. Thereby, the influence of housing geometry and guide plates has rarely been addressed. This study focuses on a CFD analysis on the oil flow of a dip lubricated spur gear stage with a guide plate. Grid-based CFD models with different simulation setups were confronted and evaluated. Results show that the selection of the simulation setup with respect to the acceleration ramp and mesh size needs to address the considered object of investigation and the desired depth of information. An appropriate simulation setup shows great accordance with recordings of the oil distribution by a high-speed camera. A detailed analysis of the simulation results identified the contribution of different gear surface zones to the no-load gear loss torque. For the considered guide plate a strong interaction of oil flow and loss torque due to pressure forces on the tooth flank surface zones and due to shear forces on the front and tip circle surface zones of the gears was determined.

Effects of Different Hard Finishing Processes on Gear Excitation

Gearboxes are essential in mechanical drive trains for power transmission. A low noise emission and thus an optimized excitation behavior is a substantial design objective for many applications in terms of comfort and operational safety. There exist numerous processes for manufacturing gears, which all show different properties in relation to the process variables and, therefore, differences in the resulting accuracy and quality of the gear flank. In this paper, the influence of three different manufacturing processes for hard finishing—continuous generating grinding, polish grinding and gear skiving—on the surface structure of gear flanks and the excitation behavior is investigated experimentally and analyzed by the application force level. A tactile scanning of the gear flanks determines the flank surface structure and the deviations from the desired geometry. A torsional acceleration measurement during speed ramp-ups at different load levels is used to analyze the excitation of the gears. The results show only a minor influence of the surface structure on the application force level. The excitation behavior is dominated by the influence of the flank modification and its deviation from the design values.

The Geometric Surface Structure of EN X153CrMoV12 Tool Steel after Finish Turning Using PCBN Cutting Tools

The article presents the results of studying the effects of coated (TiN, TiAlN) and uncoated polycrystalline cubic boron nitride (PCBN) machining blades on the key geometric structure parameters of the surface of hardened and tempered EN X153CrMoV12 steel after finish turning. A comparative analysis of the use of coated and coated cutting tools in finish turning of hardened steels was made. Tool materials based on polycrystalline cubic boron nitride PCBN (High-CBN; Low-CBN) have been described and characterized. The advantages of using TiN and TiAlN-coated cutting tools compared to uncoated were demonstrated. The lowest influence of the feed on the values of all tested roughness parameters was noted for surfaces treated with TiN- and TiAlN-coated tools (both with 50 vol.% of CBN). For uncoated tools (60 vol.% of CBN) for feeds f = 0.2 and 0.3 mm/rev., the highest values of Ra and Rz roughness parameters were found. Moreover, the lack of protective coating contributed to the occurrence of intense adhesive wear on the flank surface, which was also in the range of the feed values f = 0.2 and 0.3 mm/rev. The analysis of material surface after treatment with the uncoated tools with the feed f = 0.2 mm/rev. showed the occurrence of the phenomenon of lateral material flow and numerous chip deflections.

Investigation of the machinability by milling of the laser sintered Inconel 625/NiTi-TiB2 composite

Introduction. The processing capability of milling a metal-matrix composite based on Inconel 625 with the addition of NiTi-TiB2, obtained by laser sintering, is investigated. The composite is intended for turbine blades manufacture and has strength characteristics close to Inconel 625, however, due to the addition of TiB2, its’ heat- and wear resistance is higher. This material is new; its machinability has not been studied yet. The aim of the work is to determine the technological capabilities of milling with end mills of this composite. Investigations. The new composite is milled with end mills, and recommendations on the selection of cutting speed, milling depth and width are obtained. Experimental Methods. Measuring end mill wear and cutting force. Wear is assessed by the flank chamfer using a microscope, and cutting forces are measured with a Kistler 9257B dynamometer. Milling is carried out at three speeds: 25, 35 and 50 m/min. To determine the optimal parameters of the depth and width of milling, the following ratios are used: 1: 1, 1: 4; 1:16, while the volume of chips removed per unit of time remained constant for all ratios. Results and Discussion. The back surface of the cutter teeth wears out more intensively. After reaching the wear chamfer along the flank surface of a value equal to 0.11 - 0.15 mm, there is a sharp increase in forces and brittle destruction of the tooth. Milling at a speed of 25 m/min guaranteed 28 minutes of stable operation, after which the amount of wear quickly approached the critical value of 0.11 mm, at a cutting speed of 50 m/min, critical wear occurred already after 14 minutes. The dependences of the cutting force on time for all selected cutting speeds, throughout the test time, have an increasing character, which indicates the effect of wear of cutters on cutting forces. It is found that the durability of cutters increases with increasing width and decreasing the depth of milling.

Investigation of Drilling Temperature in Relation to Machining Conditions and Cutting Time

Controlling drilling temperature and thrust forces play a significant role in reducing tool wear and improving machining efficiency. In this work, drilling experiments are set up to measure flank surface temperature via thermocouple sensor wires passed through the coolant holes of 10mm twist drill and brazed to the drill flank surface. The testing setup is an inverted drilling jig where the workpiece (Aluminum 6061-T6 rod) is chucked into the spindle of a vertical machining center. Thrust forces are co-measured using Kistler type 3-component plate dynamometer attached to the table. A design of experiment (DOE) using JMP-SAS/STAT® was adopted for selecting combinations of cutting speed and feed values that cover a wide range. Drilling temperature rise and thrust forces are found to correlate with cutting conditions of feed (f), maximum cutting speed (V), and drilling depth (Dp). Nonlinear regression analysis produced correlating equations of flank temperature rise and thrust forces to conditions and follow a mechanistic power law of the form a1fa2Va3Dpa4 where a1, a2, a3 and a4 are identified via regression fitting.

A Novel Approach to Determine the Cutting Temperature Under Consideration of the Tool Wear

In metal cutting process, modeling and predicting the tool wear development has been researched for decades. Many efforts have been made to study the cutting temperature as an indicator for the tool wear behavior. However, the determination of the cutting temperature in the critical contact area in process is still a challenge. In order to build temperature-dependent tool wear models, the temperature distribution of the workpiece was captured in this paper by an infrared thermography in orthogonal cutting of Direct Aged Inconel 718 with cemented carbide cutting tool WC-15Co. Instead of studying the temperature in critical cutting zone directly, the workpiece temperature distribution around the flank wear surface was determined inversely with the analytical Jaeger-solution based on the experimental data. The determined maximum cutting temperature on the flank wear surface has been successfully verified by FEM chip formation simulations. By means of this inverse approach, the cutting temperature on the flank surface can be determined as a function of tool wear VB. The experimental results showed that the cutting temperature increased with the increase of the tool wear VB. By means of this method, the temperature on the flank wear surface can be used as an important physical indicator to model and predict the tool wear development in future work.