Rake Angle Research Articles

PROFILING OF CUTTING TEETH OF A GEAR SHAPING HEAD

This paper investigates a possibility of the use of the mathematical model of the cutting edge profile developed for turning form cutter in the profiling the cutting edge of the tooth of a gear gushing head. The corresponding cutting tooth of the gashing head was carried out with Mathcad commercial software package accounting for the rake and clearance angles. The use of the same mathematical model increases the degree of automation of the design of various types of form cutting tools, which is the goal of many research work in the field of tool design and its manufacturing. In order to apply the mathematical model of the tuning form tool during the profiling of cutting teeth of a gear gashing head, arrays of coordinates of the points of the involute profile of the tooth are formed accordingly. This was carried out accounting on the difference in the motions of cutting edge of the tuning form tool and that of a gear gushing head. Moreover, the obtained results allow to conclude that the developed generalized mode can be used not only for great gushing tools but also for gear generating tools as gear shaper cutters.

The 1895 Ljubljana earthquake: source parameters from inversion of macroseismic data

The 14 April 1895 (Mw 6.1, in the area of Ljubljana, Slovenia) earthquake is still not fully understood. The aim of this work is to derive information about its source from the inversion of an updated dataset of intensities (evaluated with EMS-98). This was done via automatic non-linear geophysical inversion KF-NGA, which was performed using a Niching Genetic Algorithm and has been presented in other articles. The distribution of damage caused by this earthquake is not homogeneous and often shows significant intensity differences between neighbouring sites. Statistical analysis of the intensities, epicentral distances and geologic nature of the sites suggests some site effects. Nevertheless, the resulting solution is consistent with regional seismotectonics, i.e. an almost pure dip-slip mechanism: strike 282° ± 5°, dip 38° ± 7°, rake 86° ± 9° (± 180° because of the intrinsic ambiguity of the KF-NGA-inversion). Since the rake angle is close to 90°, there is an almost perfect ambiguity between the two planes of the focal mechanism. Therefore, our solution has a Dinaric direction and could be associated either with a fault plane that dips NE or with one that dips SW.

Micromilling of high-aspect-ratio ceramic thin walls with customized micro PCD end mills

With the increasing application of ceramic structural parts, how to realize the ductile cutting of ceramics and high-quality machining of ceramic structural parts have become an important research direction. In this paper, the micromilling of fully sintered zirconia ceramics is studied using customized PCD end mills with three different rake angles. The critical thickness for microcutting of ceramics during the micromilling process is theoretically analyzed and experimentally identified. Then, the ductile cutting of ceramic materials is to be realized by controlling the key cutting parameter (feed per tooth fz) considering the critical cutting thickness. Under the condition of ductile cutting, the high-aspect-ratio vortex curved thin walls of fully sintered zirconia ceramics are successfully fabricated. Furthermore, the tool wear of the customized PCD end mill is analyzed. The tool geometric parameters that are beneficial to ensure both ductile cutting and high tool life are identified.

A Hybrid Nondominant-Based Genetic Algorithm (NSGA-II) for Multiobjective Optimization to Minimize Vibration Amplitude in the End Milling Process

Aluminium is a noncorrosive, lightweight material used to fabricate parts for the aerospace, automobile, and construction industries. Due to the low-temperature resistance, more heat is generated. At the same time, in machining, tremendous efforts are taken to keep friction and chatter to a minimum and to attain better quality and perfect output, and also more attention is required while selecting the machining process parameters. Spindle speed, rate of feed, radial and axial depth of cut, and radial rake angle of the tool are the parameters utilized to machine aluminium 6063 using the HSS tool on CNC milling to estimate spindle and worktable vibration using a prediction model. In this study, the design of the experiment of the response surface methodology approach is used to create a second-order statistical equation for experimentation with the Design-Expert v12 software. The performance characteristics are analyzed using the ANOVA method. The spindle speed achieved the lowest vibration between 2000 and 3000 rpm. Next, axial and radial depths were the most vibration-affecting parameter compared to the rate of feed and radial rake angle of the tool. To find the best feasible response, the nondominant sorting genetic algorithm II (NSGA II) approach was trained and tested using MATLAB software. Using a Pareto-optimal technique, the optimum worktable vibration ranged from 0.00284 to 0.00165 mm/s2, whereas the spindle vibration ranged from 0.02404 to 0.01336 mm/s2. The predicted values were found to be in an excellent argument when Pareto-optimal solutions are used.

Force coefficient characterization in machining of UD-CFRP using numerical-analytical approach

A numerical-analytical approach was utilized to construct a predictive model of cutting force for machining unidirectional carbon fiber reinforced polymer (UD-CFRP) laminates. The force coefficients in the model, which include friction angle, shear plane angle, shear strength, and rebound height, can be characterized by the fiber orientations ranging from 0° to 180°. The accuracy of the model was confirmed through experimental verification. The results indicate good agreement between the predicted and experimental values, with relative errors below 14.8%, except for the thrust force at 90°. Additionally, the study examined the influence of rake angle and flank angle on the cutting force, revealing two critical points in the predicted cutting force curve throughout the fiber orientation. These turning points shifted with changes in the rake angle. For instance, the value of the first critical point changes from 60° to 45° when the rake angle range shifts from [0°, 5°] to [10°, 15°]. This indicates that a larger rake angle facilitated an earlier transformation of chip formation mode, leading to a decrease in cutting force. Furthermore, the cutting force decreased as the rake angle increased between the two turning points. The impact of the flank angle on the cutting force was determined to be minimal, and the turning points’ positions remained consistent as the flank angle increased.

Design, construction and evaluation of a miniature soil bin plus predicting the measured parameters during primary tests using ANFIS

A clear understanding of soil-machine interaction is utilised in many areas, such as rational design and performance optimisation of soil-engaging tools/implements. This research developed a new soil bin to investigate the interaction between soil-narrow tines and soil failure. The new soil bin consisted of a chassis, a bin, a variable speed carriage and a bolt and nut type power transmission system between the motor and carriage. The design criteria of the new soil bin were based on the drive system's immediate acceleration of the carriage unit. A curved chisel tine was tested to evaluate the system's capabilities. Three parameters, including lift height, failure side area and forward failure distance, were investigated at two forward speeds of 0.037 and 0.05 m/s and three rake angles of 5°, 10° and 20°. An analysis of variance (ANOVA) test revealed the effect of rake angle on the lift height, failure side area, and forward failure distance was significant (P < 0.01). However, the forward speed did not have any significant influence on parameters. Also, the lift height and failure side area increased significantly (P < 0.01) by increasing the rake angle, while the forward failure distance decreased. Regarding soil failure, the results were in harmony with Godwin and Spoor's model. The regression and ANFIS models were developed to predict the output parameters by considering input parameters. The R2 values and ANFIS models were 0.4895, 0.7264, 0.9856, and 0.9999, 1, 1, respectively, for lift height, side area, and forward distance. Therefore, ANFIS approach was more accurate for predicting soil failure parameters.

CUTTING FORCE OPTIMIZATION OF MACHINING OF KEVLAR (K-129) FIBER REINFORCED PLASTIC COMPOSITES MATERIALS

Machining of composite materials presents challenges due to the material's abrasive reinforcement as well as its anisotropic and nonhomogeneous properties. Near-net-shape composite goods are typically made, however machining techniques such as milling or drilling are routinely utilized for dimensional precision and assembly purposes. Laminate of Kevlar epoxy is made by hand lay-up. On a Beaver Milling Machine, laminates are cut orthogonally using a single-point carbide cutting tool with different rake angles. Cutting forces were measured at different cutting speed and depth of cut. It is critical to accurately forecast cutting forces during the machining process of fiber-reinforced polymer composites in order to design and improve such processes. The aim is to reduce the cutting force required to a minimum. Response surface methodology was employed for modeling and optimization. Additional experiments corroborate the findings.

Качество обработки поверхности и эффективность резания в кунжутном масле во время механической обработки: регрессионный анализ

This study evaluates the use of gingelly oil as an eco-friendly cutting fluid for the turning operation. Experiments were conducted to determine the effect of nose radius, and rake angle on tool wear, surface formation, and cutting force. In addition, different lubrication techniques, such as cutting fluids and bio-oils, were investigated to determine their potential for minimising friction, heat generation, and tool wear during machining. In comparison to dry cutting, and conventional petroleum-based lubricants, the results demonstrate that gingelly oil consistently produces smoother surface finishes, and reduces cutting forces. The relationships between cutting parameters, and surface finish were analysed using statistical modelling, with R-square and p-values used to quantify correlations and predictor significance. The findings highlight the viability of gingelly oil as a cutting fluid and the significance of optimising process parameters for increased machining efficiency.

Investigations on chip breakability in lead-free brass alloy CW511L using different chip breaking geometries

Brass is an alloy of copper and zinc, commonly alloyed with lead. Due to legal restrictions, the lead-content is decreasing nowadays. This leads to higher cutting forces and worse chip breakability. To face these challenges, adapted tool geometries were investigated. To decrease cutting forces, positive rake angles can be utilized. On the other hand, this will lead to worse chip breakability in single phase lead-free brass alloys. Therefore, chip breaking geometries are necessary. This paper investigates and compares different forms of chip breaking geometries to improve chip breakability when using highly positive rake angles in lead free brass alloy CW511L.

Mechanics and surface characterization of high-speed diamond turning of germanium

Germanium and other brittle single crystal materials can be diamond turned with negative rake angle tools, but to maintain surface integrity parameters are typically chosen conservatively. This work describes experiments performed on (100)Ge crystal samples that support a recent scientific finding: increasing the surface speed in diamond turning of germanium improves surface integrity. Materials are machined on a modern ultraprecision diamond turning machine at constant surface speed and constant feed per revolution keeping both the geometric character and the material flow dynamics constant during machining. Forces are measured in the experiments at cutting speeds ranging from 0.2 m/s to 10 m/s. Surface roughness of the machined surfaces was characterized using coherence scanning interferometry and surface analysis. The key findings of the work are (a) force and specific forces decrease by approximately a factor of 2 over the cutting speed range and (b) surface damage substantively decreases with cutting speed. This is correlated to the behavior of the cutting forces during machining and the chip geometry. The findings indicate that higher material removal rates can be obtained in diamond turning of germanium and that this increase in material remove rates also improves surface integrity.

Effect of cutting speed on the surface integrity of single point diamond turned (100)Ge

The surface integrity of single crystal (100)Ge machined by on-axis single point diamond turning was investigated. The specimen was machined with a -25◦ rake angle single crystal diamond tool, with a depth of cut of 10 μm and a feedrate of 4 μm/rev. Six circular bands were machined on the specimen at different cutting speeds, ranging from 0.2 m/s to 10 m/s, while keeping all other machining and geometrical parameters constant. The surface topography was measured by atomic force microscopy and the near surface lattice disorder was investigated by Raman spectroscopy. The cutting and thrust forces were measured during machining, and their frequency domain was analyzed. Machining resulted in four lobes with four-fold symmetry, with differing amounts of surface fracture at each cutting speed. It was found that increasing the cutting speed generates surfaces with less or no brittle fracture for all cutting directions, causing some lobes to be undistinguishable. As the speed increased, the cutting and thrust force decreased monotonically. The frequency content of the force changed accordingly with the appearance of the surface, with a shift from 8 oscillations per revolution to 4 oscillations per revolution.

Optimizing rock breaking performance: The influence of chamfer on polycrystalline diamond compact (PDC) cutters

Research on the rock-breaking performance of the Polycrystalline Diamond Compact (PDC) cutter has primarily focused on sharp cutters, often overlooking the influence of chamfer. Notably, the design of chamfer parameters has been largely unreported. In this study, we established a theoretical model of cutting force that takes chamfer into account. We analysed the primary and secondary relationships of four factors – back rake angle, depth of cut, chamfer angle, and chamfer length – on the force of the PDC cutter. This was done through a pseudo-level orthogonal level test. A numerical simulation, based on the Smooth Particle Hydrodynamic (SPH) method, was conducted to analyse the rock-breaking force and stress distribution characteristics of PDC cutters with different chamfer angles. Combined with a drop hammer impact test, we provided an optimized design of chamfer parameters. Our findings revealed that while the chamfer had a relatively minor influence on the force of the PDC cutter, it contributed to the optimal distribution of stress on the PDC cutter. This effectively protected the cutting edge and prevented early cracks and spalls of the cutter. When the chamfer angle was less than or equal to the back rake angle, the resultant force of the PDC cutter increased with the increase of the chamfer angle. However, when the chamfer angle was greater than the back rake angle, the resultant force of the PDC cutter first increased and then slightly decreased with the increase of the chamfer angle. Additionally, the resultant force of the PDC cutter increased approximately linearly with the increase of chamfer length. When the chamfer angle of the PDC cutter was between 30° and 45°, the fluctuation of the cutting force was relatively smooth, the rock-breaking process was stable, and the cutter’s impact resistance energy was relatively higher. These findings will provide valuable guidelines for the design of chamfered PDC cutters.

Energy consumption of the biomass cutting process preceding the biofuel production

This paper explores the effects of various parameters on the triticale straw cutting process and the subsequent biomass yield. The impact of blade angle (α), rake angle (β), and the distance between the blade and counter-blade (g) were examined in relation to the shaft torque (Td) on the cutting knife drum, the energy consumption (Ec), and the required power (P) for processing straw. Heterogeneity among straw samples was taken into account to ensure accurate calibration of responses. An analysis of variance (ANOVA) was employed to investigate the interactions between input variables and recorded responses, leading to the identification of optimal cutting parameters (α = 35° and β = 0°) that minimise Td, Ec, and P. Additionally, the components of the recorded torque Td, including cutting torque (Tc) and friction torque (Tf), were analysed. Parameter f was used to ascertain the percentage of Tf in Td, enabling an optimisation process that confirmed the experimental results and pinpointed the parameter values that resulted in the least energy-intensive process.

Ductile–brittle transition and ductile-regime removal mechanisms in micro- and nanoscale machining of ZnS crystals

The ductile–brittle transition and ductile-regime removal mechanisms of ZnS crystal, a typical soft-brittle infrared optical material, have remained unclear at the micro- and nanoscale. In this context, this study modeled the energies consumed in two machining modes, namely ductile deformation and brittle fracture, during the ultraprecision cutting of ZnS crystal. Subsequently, based on the transition point of the energy mode, the critical undeformed chip thickness (CUCT) for the ductile–brittle transition of the material was determined. Additionally, the effect of tool parameters on CUCT was quantitatively analyzed, and the correctness of the model was verified by scratch experiments. Moreover, the cutting parameters that affect the maximum undeformed chip thickness (MUCT) were analyzed. By comparing the MUCT and CUCT, the cutting conditions to realize ductile-regime machining were predicted. The correctness of the ductile-regime machining conditions was also verified through surface quality characterization after face-cutting experiments. The MUCT can be controlled to be less than the CUCT by using a cutting tool with a sufficiently large tool rake angle, a nose radius and a reduced feed rate, thus realizing the ductile-regime removal of the material. The surface morphology, chip morphology, and surface roughness of machined ZnS crystal confirmed the validity of the model. Using a diamond cutting tool with a large cutting edge angle (–25°) and nose radius (1.2 mm) as well as a low feed rate (0.5 μm/rev) and depth of cut (3 μm), the generation of cracks and pits was effectively inhibited, resulting in a smooth surface with a surface roughness of 1.60 nm. Overall, the findings of this study provide important insights into the superfinishing of soft–brittle materials such as ZnS crystal.

Structure Design of Bionic PDC Cutter and the Characteristics of Rock Breaking Processes

The rational structural design of polycrystalline diamond compact (PDC) cutters effectively enhances the performance of drill bits in rock fragmentation and extends their service life. Inspired by bionics, a bionic PDC cutter was designed, taking the mole claw toe, shark tooth, and microscopic biomaterial structures as the bionic prototypes. To verify its rock-breaking effectiveness, the finite element method was employed to compare the rock-breaking processes of the bionic cutter, triangular prism cutter, and axe cutter. The study also investigated the influence of different back rake angles, cutting depths, arc radii, and hydrostatic pressures on rock breaking using the bionic cutter. Prior to this, the accuracy of the finite element model was validated through laboratory tests. Subsequently, a drill bit incorporating all three types of cutters was constructed, and simulations of rock breaking were conducted on a full-sized drill bit. The results demonstrate that the bionic cutter exhibits superior load concentration on the rock compared to the triangular prism cutter and the axe cutter. Additionally, its arc structure facilitates the “shoveling” of the rock, making it more susceptible to breakage under tensile stress. As a result, the efficiency of the bionic cutter surpasses that of the triangular prism and axe cutters. Similarly, it exhibits minimal fluctuations and values in cutting force. As the back rake angle and cutting depth increase, the MSE and cutting force of all three cutters also increase. However, the bionic cutter consistently maintains the lowest MSE and cutting force, confirming the superiority of its bionic structural design. The MSE and cutting force of the bionic cutter fluctuate with the increase of the arc radius, and the optimal arc radius falls within the simulation range, between 21 mm and 23 mm. Compared to the other two types of cutters, bionic cutters possess a unique structure that allows for better release of internal stress within the rock, thereby ensuring higher efficiency in rock-breaking, particularly in deep geological formations. The rock breaking simulation results of full-sized drill bits show that the use of a bionic cutter can improve the drill bit’s ability to penetrate the formation, reduce the possibility of drill bit bounce during the rock breaking process, prevent the occurrence of stick-slip, improve the drilling stability, effectively improve the efficiency and service life of the drill bit during the rock breaking process, and reduce the drilling cost. It is concluded that the research results of bionic PDC cutters are helpful to the development of high-performance drill bits and the reduction of drilling costs.

Research on friction characteristics of the support mechanism of the drilling robot under axial-torsional load

Because the coiled tubing drilling robot (CTDR) needs to pull the coiled tubing (CT) and provide the weight on bit (WOB), the traction force is an essential parameter for evaluating the performance of the CTDR. The friction performance between the support mechanism of the CTDR and the borehole wall will directly affect the traction force. At present, there is not a research paper about the mechanical behavior of the interaction between the support mechanism and the borehole wall. On this basis, a model of contact mechanics of the friction block of the support mechanism and the borehole wall was established. The model of contact mechanics integrates the combined factors of the torsional forces and axial forces generated by the drill bit and the CTDR. The friction performance between the friction block of the support mechanism and the borehole wall under different parameters and conditions was investigated. It is found that the size of the rake angle of the tooth has little effect on the damage of the borehole wall only under normal force. And, the rake angle of the tooth is negatively correlated with the equivalent friction coefficient. The embedded depth is positively correlated with the equivalent friction coefficient. When the rake angle of the tooth is greater than 35°, the influence of the embedded depth on the equivalent friction coefficient is weakened. When the embedding depth of the friction block reaches 0.3 mm, the equivalent friction coefficient is greater than 1. When the bevel angle of the tooth is 20°, the friction block performs best. The optimized structural parameters of the friction block are as follows: rake angle of the tooth of 35°, back angle of 60°, spacing of 4 mm, and bevel angle of the tooth of 20°. Further contact experiments were conducted between a single tooth of the friction block and a rock sample. The differences between the experimental results and the numerical simulation results were analyzed. The correctness of the theoretical model is verified by experiments. This paper reveals the relationship between structural parameters and equivalent friction coefficient. The results can provide a theoretical basis for the structural design of the friction block for high-safety and high-traction CTDR.

Variation in Rake Angles of Heterogeneous Source Models

Variation in Rake Angles of Heterogeneous Source Models

Study of a Methodology for Calculating Contact Stresses during Blade Processing of Structural Steel

The article presents data about the distribution of contact stresses on the rake surface of the cutter when turning steel (Fe-0.4 C-1Cr), which were obtained by the split cutter method. The article also provides graphs of the effect of the uncut chip thickness a and the rake angle γ on the main parameters of the plots of shear τ and normal σ contact stresses. For this case, The initial data were obtained by longitudinal turning of a steel workpiece with the measurement of the technological components of the cutting force by a three-component Kistler dynamometer, followed by the calculation of the physical components of the cutting force. The rake angle varied widely, from +35 to −10°, and the uncut chip thickness a varied from 0.05 to 0.37 mm. A decrease in the rake angle from +35 to −10° leads to a significant increase in the maximum normal contact stress at the cutting edge σmax: from 400 to 1400 MPa with the uncut chip thickness a = 0.37 mm. In the area of small uncut chip thickness, a (less than 0.1 mm), the paradoxical increase in the magnitude of the greatest normal contact stress with a large positive rake angle (more than +15°) is explained by the indentation (pressing) of the being machined material under the rounded cutting edge of the cutter in the chip formation zone, and their paradoxical decrease with a negative rake angle is due to the presence of a sag (deflection) of the transient surface. According to the magnitude of the reference points obtained on the basis of experimental data, it is possible to plot the contact stresses epures on the rake surface of the cutting tools when machining steel.

Material Removal Mechanism and Evolution of Subsurface Defects during Nanocutting of Monocrystalline Cu

Multigroup large-scalenanocutting models of monocrystalline Cu were established by molecular dynamics simulations to investigate the influence of cutting parameters on the material removal mechanism. The formation and distribution of subsurface defect structures were revealed, and the evolution behavior of the complete prismatic dislocation loop was analyzed in depth. It was demonstrated that the chips and machined surface of monocrystalline Cu were mainly formed under the coupling effect of shearing and extrusion forces. A diamond tool with a larger edge radius or a negative rake angle could produce a noticeable suppression on the chip formation. The corresponding relationship between the location of defect atoms and the distribution of von Mises stress was studied, which indicated that the shear stress would become larger at the subgrain boundaries, dislocation lines, and the amorphous atoms than that in their nearby regions. The complete prismatic dislocation loop was formed by cross-slip between two sets of stacking faults; meanwhile, the generated multiple Lomer–Cottrell locks hindered its movement and promoted the work-hardening phenomenon. These research results are of great theoretical value to enrich the nanocutting mechanism and technology of plastic materials.

Влияние формы тороидальной задней поверхности на углы режущего клина и механические напряжения вдоль режущей кромки сверла

Introduction. Drilling holes with standard tolerance varying from IT8 to IT12 is widely used in industrial production. However, at present time, there are neither comprehensive studies, nor scientifically justified recommendations for the rational choice of the geometry of the cutting part of drills with a toroidal flank surface. Therefore, the computer-aided design (CAD) of new drill designs with a toroidal flank surface and finite element modeling (FEM) of the stressed state of its cutting part are important tasks. The purpose of the work is reducing both the range of change in the rake angle and the wedge angle of the cutting wedge along the cutting edge from the periphery to the center and the equivalent stresses in the cutting wedge. In this paper we investigate changes in the rake and wedge angles of the cutting wedge depending on the radius of the generatrix line of the toroidal flank surface as well as changes in equivalent stresses in the cutting wedge, which depend on changes in the radius of the generatrix line of the toroidal flank surface. The research methods include the fundamentals of the theory of cutting, CAD methods, and the FEM, which was applied in this work to new drill designs. Results and discussion. It is found that the range of changes in the rake angle and the wedge angle of the cutting wedge of the drill decreases compared to the standard design with decreasing radius of the generatrix line of the flank surface. A CAD system for drills with a toroidal flank surface is developed. As a result, the range of changes in the rake angle along the cutting edge decreased by 86 % for a drill with a minimum radius of the generatrix line of the toroidal surface compared to that with the conical flank surface, the range of the wedge angle of the cutting wedge decreased by 56 %, and the maximum equivalent stresses decreased by 2.13 times. It is also important to note that in this case, the wedge angle is close to constant for half of the drill tooth. These indicators exceed those for existing designs of the twist drills that indicate the key achievement of this paper.