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Oxley shear angle model. a Oxley’s parallel-sided slip-line model. b Elemental forces acting at the primary and second shear zone
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Drilling mechanics model has always been the key and difficult point in the research field of gun drilling. In this paper, through theoretical analysis and processing experiments, the gun drilling mechanics model of Ti6Al4V titanium alloy is studied. On the one hand, based on the Oxley cutting model and the Johnson-Cook flow stress model, this pape...
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Citations
... S.V. Kirsanov et al. analyzed the small diameter gun drill (diameter Φ 2.05 mm) on the quality of drilling surface [7]. Li et al. established a new mechanical model of gun drill and analyzed the influence of cutting parameters on axial force and torque [8,9]. To address the rapid tool degradation and poor hole straightness issues, Neon D presents a development of polycrystalline cubic boron nitride (PCBN)-tipped gun drill [10]. ...
With the continuous development of the manufacturing industry, the proportion of deep hole machining in mechanical processing is increasing. In 304 stainless steel, as a kind of difficult machining material, its deep hole machining demand is also increasing year by year. Due to the physical characteristics of 304 stainless steel and the uncontrollability of gun drilling, the quality of deep hole processing is relatively poor. In this paper, some experimental studies are carried out to solve this engineering problem. Firstly, by analyzing the structure of the gun head, this paper establishes the stress model of the gun head in the processing process. Then, the accuracy of the theory is verified by experiments. Secondly, this research carried out multiple single-factor drilling experiments to change the front angle of the internal and external edges of the gun drill to control the cutting force in the machining process. Based on the analysis of the test results, the influence of the change of the gun drill’s internal and external edge angle on the surface quality of hole wall, chip forming, and hole straightness offset is explored. The results show that the increase in the internal angle of a gun drill can promote the surface roughness of the hole wall and chip forming. And properly increasing the external angle can slow down the straightness offset of the hole. Finally, for the deep hole processing of 304 stainless steel, this paper gives the best edge angle selection of gun drill.
... Yu et al. studied the influence of coolant oil pressure on straightness error [8,9]. Li et al. studied the influence of drilling force on straightness error [10,11]. Deng et al. studied the theoretical model of straightness error of single support gun drilling processing system [12]. ...
Deep-hole drilling (depth-diameter ratio > 10) accounts for about 40% of hole processing. As an important hole processing technology, the gun drill has a complex structure and weak relative stiffness, which makes it difficult to avoid the straightness deviation of the hole. Also, the current theoretical model of straightness deviation is inconsistent with the actual working condition of deep hole gun drilling, so the prediction of straightness error is still tricky in deep hole machining. Based on the analysis of influencing factors of straightness deviation of gun drilling, this paper establishes the theoretical model of the straightness error of the middle four supports by using the Euler–Bernoulli beam theory and reveals the relationship between the bit deflection and the deviation of the hole axis. In this paper, the influence of support clearance, support spacing, support stiffness, axial force, and drill pipe stiffness on straightness error is analyzed through simulation and experiments. The method to reduce straightness deviation by controlling support clearance is proposed and verified by experiments.
... The inner diameter of the workpiece was the same as the outer diameter of the BTA drill, the wall thickness was 10 mm, and the height was 12 mm, which could not only reduce the calculation, but also completely cover the contact area between the guide pads and the hole wall in the axial direction. The workpiece material was pressure vessel steel SA-5083, with the constitutive relation described by the J-C model [29], and the model parameters were as shown in Table 2. ...
The goal of this study was to explore the self-guided machining mechanism of boring and trepanning association (BTA) deep hole drilling and realize precise control of the machining quality. The motion analysis method was used to analyze the center motion trajectory of the drill during the entrance, and the self-guiding mechanism and hole-forming mechanism of BTA deep hole drilling were revealed. Considering the bending deformation of the drilling tube and the tool structure parameters, according to the elastic-plastic deformation theory and Hertzian contact theory, a novel analytical model of the extrusion contact between the guide pads and the hole wall of the BTA deep hole drilling was established for the theoretical prediction of the extrusion deformation and the machining hole diameter. Combined with the finite element method (FEM) simulation model, the variation law of the contact inclination angle, contact stress, and extrusion deformation of the guide pads and the hole wall with the drilling conditions were studied. The total extrusion deformation between the guide pad and the hole wall was between 10 and 50 μm. The maximum error between the FEM simulation results and the test results was 18.1%, and the maximum error between the analytical model results and the test results was 23.6%. The simulation and experimental results showed that the established extrusion contact model could accurately predict the extrusion deformation of the hole wall and the machining hole diameter.
... et al. gave a small diameter gun drill (diameter Φ2.05 mm) Test parameter of influence of cutter parameters on the surface quality of the drilling hole [7]. Li Liang et al. established a new mechanical model of gun drill and analyzed the influence of cutting parameters on axial force and torque[8][9]. Zhang used ANSYS software to analyze the dynamic characteristics of gun drills of different materials, which provided a reference for reducing the vibration and deformation of gun drills[10]. Ahmed et al. studied the influence of coolant pressure and rotating speed on the machining straightness of 718 super alloy gun drill[11]. ...
With the continuous development of the manufacturing industry, the proportion of deep hole machining in mechanical processing is increasing. Demand for deep hole processing of 304 stainless steel is also increasing year by year. At the same time, due to the physical characteristics of 304 stainless steel and the uncontrollability of gun drill in processing, the quality of deep hole processing is relatively poor. The main research of this paper is as follows. Firstly, the stress model of drill bit is established by analyzing the structure of the drill bit. Secondly, a number of single-factor drilling experiments are carried out to control the cutting force in machining process by changing the forward angle of the inner and outer edges of the gun drill. Thirdly, based on the analysis of test results, this paper discusses the influence of the change of inner and outer edge Angle of gun drill on the surface quality of hole wall and the deviation of hole straightness. Finally, the paper studies the chip forming process of gun drill in deep hole machining of 304 stainless steel, and gives the best choice of cutting edge Angle.
... Yu Daduo et al. studied the influence of coolant oil pressure on straightness error [8][9]. Li Liang et al. studied the influence of drilling force on straightness error [10][11]. Deng et al. studied the theoretical model of straightness error of single support gun drilling processing system [12]. ...
... Simplify Eqs. (8)(9)(10)(11)(12), ...
... When the spindle reaches the first support, the first support is pushed to move axially together, so that the distance between the spindle and the second, third support, and fixed chip-box support is gradually reduced. The second stage bending moment model is established, and the analysis process in this stage is the same as that in the first stage, but 11 M is not considered. The moment for the section 1 ...
Deep-hole drilling (depth-diameter ratio > 10) accounts for about 40% of hole processing. As an important hole processing technology, the gun drill has a complex structure and weak relative stiffness, which makes it difficult to avoid the straightness deviation of the hole. In addition, the current theoretical model of straightness deviation is inconsistent with the actual working condition of long and deep hole gun drilling, so the prediction of straightness error is still a difficulty in deep hole machining. Based on the analysis of influencing factors of straightness deviation of gun drilling, this paper establishes the theoretical model of the straightness error of the middle four supports by using the Euler-Bernoulli beam theory and reveals the relationship between the bit deflection and the deviation of the hole axis. In this paper, the influence of support clearance, support spacing, support stiffness, axial force, and drill pipe stiffness on straightness error is analyzed through simulation and experiments. The method to reduce straightness deviation by controlling support clearance is proposed and verified by experiments.
... Both the design and the materials and coating used in deep-drilling technology have evolved [8]. The most recent solution is the design of gun-drill tool bodies with interchangeable cutting plates and interchangeable guide surfaces that provide the additional adjustment of dimensions using different washer widths [9]. Nevertheless, even with the use of the latest auger design, one of the most important conditions for maintaining a stable process is still relevant, namely the application of sufficient cutting fluid pressure to dissipate heat, to remove chips and to provide the cutting process with lubrication [10][11][12]. ...
The drilling process in real production places ever-increasing demands on the length and accuracy of the holes made. The drilling of holes beyond a length-to-diameter ratio of 5–10 is called deep drilling. The aim of the research was to determine in detail the deep-drilling process input conditions, their impact on the stability of the cutting process and the degree to which the output requirements were achieved. The focus of the analysis was on how the monitored technological and physical impacts translate into achieving the required gun-drill life and the quality and dimensional accuracy of deep holes, as well as their overall impact on tool life. Based on the analysis, tests were conducted to verify the impact of individual parameters on tool life. The obtained results were then statistically evaluated and optimized. Drawing on the evaluated experimental results, solutions and procedures were proposed and implemented in the environment of a real operation. This research obtained the optimal values of the frequency of rotation and displacement to ensure maximum tool life while maintaining the efficiency of the production of drilled parts. At the same time, based on the research, a methodology and recommendations for deep-drilling technology were developed.
... One of the most important roles in setting up the numerical analysis is represented by the phenomenological models since they dictate the accuracy of the model in representing the real materials behavior being processed. It is generally known that Johnson-Cook [7] model is one of the most widely used, but despite its versatility, it is purely empirical. Thus, its ability to describe the material constitutive behavior is limited into the range of the data used to find the material constants, which need to be re-calibrate at varying the working conditions [8]. ...
This paper presents a physics-based model able to simulate the flow stress behavior of the Ti6Al4V alloy during subsequent severe plastic deformation processes, namely turning and burnishing. All the physical and metallurgical mechanisms that accommodate the deformation were considered to describe the material strengthening and they were implemented via user subroutine in a commercial finite element software. Then, the proposed numerical model was used to investigate the effect of combined turning/burnishing processes on the surface integrity of manufactured Ti6Al4V components. Turning and roller burnishing experiments were conducted to validate the proposed finite element model and to analyze the microstructural phenomena and the output variables. The implemented model well fits experimental results, precisely predicting the evolution of grain size, dislocations, hardness, and residual stresses. Different process combinations can lead to similar microstructures and information on different contributions can be highlighted through physics-based modelling and simulated process combinations.
Graphical abstract
... As shown in Fig. 4, each position was measured three times, and roughness was calculated in VK analysis software. The force of the drill bit is complicated [17] , which can be divided into normal force, circumferential and axial friction force on the support surface of the guide strip, normal force and tangential friction force on the inner and outer cutting edges, and normal force formed by the cutting fluid on the outer diameter clearance surface. The overall stress analysis is shown in Fig. 5. ...
There are a lot of problems exist in the processing of long and thin deep hole gun drilling of high strength steel, such as insufficient of the machining mechanism and characteristics of gun drilling, difficulty in selecting machining parameters, unknown influence mechanism of machining parameters on drilling force, drilling temperature and machining quality. In this paper, 42CrMo high strength steel is selected as the workpiece material. A numerical model of cutting force is established based on the mechanism of gun drill, and then the finite element simulation and processing test are carried out. The results show that the cutting force decreases with the increase of cutting speed, and increases with the increase of feed speed; the error between the theoretical and actual value is less than 10%. Cutting speed and feed speed have a great influence on machining quality, and the cutting fluid pressure mainly affects the surface roughness.
... The drill pipe of gun drill is a typical weak rigid member, which will bend under the thrust force and lead to the straightness deviation. The thrust force (F z ) increases by various factors such as the increase in feed rate, tool wear and chip clogging [15,16]. The simulations were run for the drill length of 1.6 m with l 1 = 0.2 m, l 2 = 0.7 m, l fs = 1.26 m , It was observed that the drill deviation increases as the thrust force increases as shown in Fig. 16. ...
Straightness is one of the key technical indicators for deep hole gun drilling. This work studies the effect of drill shaft support misalignment on hole straightness in relation to various control factors. Misalignments occur in machine spindles, intermediate supports and pilot bushings. A predictive hole straightness deviation model for multi-support deep hole drilling process is introduced using the Euler column theory. The model considers the effect of the misalignment of whip guides in addition to the effects of the varying distance among the supports. The model also takes into account the effects of the thrust force and the drill lengths. Through simulation, this work analyzes the effect of each control factor on the results and optimizes the setting for each control factor. Further experiments on Ti6Al4V alloy then verify these estimates. Through research, fixed support at chip box has a greater influence on straightness deviation as compared to the misalignment at other supports; the distance between supports nearer to the chip box has more control on straightness deviation as compared to the other support distances.
In recent times, the move towards sustainable manufacturing is guiding industries to adopt a low-impact manufacturing methodology that can boost productivity and reduce environmental impact. In this novel study, an evaluation of Deep Hole Drilling on AISI1045 under three different cooling techniques Flood, Emulsion, and Mist cooling was carried out. Traditionally, the flood cooling technique is used as the cooling and lubricating method, in which an increased amount of coolant is supplied with high pressure to remove chips from the machined surface. But it has negative effects on the environment, health, and machining cost. To overcome these constraints mist cooling is used as the lubricating technique which has shown promising results in many machining processes. To carry out the experimentation, three input process parameters Spindle Speed, Cutting Feed, and Pressure of the coolant were taken and Surface roughness, circularity, cylindricity, Hole wall Temperature, and tool wear were considered as output parameters to measure the hole quality. Among all the cooling techniques, mist cooling proved to be worthy in terms of attaining sustainability and produced good results in terms of Surface Finish, Tool Wear, and Hole Profile. Tool wear under mist cooling was reduced by 13–28% and 25–35% when compared with Cutting oil and emulsion, respectively, which may be attributed to reduced abrasion and adhesion under mist cooling. The surface finish was improved by 42–50% and 20–32% improved under mist cooling when compared with cutting oil and emulsion, respectively.
