Alloy Thin-walled Parts Research Articles

The influence of cutting mode elements on the technological parameters of the process of milling blanks of titanium alloy thin-walled parts

The purpose of a rational mechanical processing mode remains an urgent task of pre-production engineering. Known recommendations and methods for selecting this mode are focused on the processing of solid blanks and do not take into account the fact that when processing thin-walled blanks, the temperatures in the processing zone and the surface layer of the blank differ. The study is aimed at identifying patterns in changing the parameters of the milling process of thin-walled blanks depending on the mode elements, as well as developing recommendations for selecting this mode. The authors performed numerical simulation of technological parameters of the milling process of solid and thin-walled blanks made of titanium alloy under various modes. The cutting speed, cutting depth and feed per cutter tooth were varied. The cutting force, power and densities of heat sources and the temperature in the surface layer of the blank, in the contact zones of the cutter tooth with the blank and the chips with the front surface of the tooth were calculated. It has been found that when milling thin-walled blanks, the temperature field differs significantly from that formed when processing solid blanks due to low heat removal from the unprocessed surface. Increasing the feed per tooth by 45% leads to an insignificant decrease in temperatures in the cutting zone (by 5...12%). Increasing the cutting speed by 25%, on the contrary, leads to an increase in temperatures by 5...10%. Increasing the cutting depth leads to an increase in the temperature in the chip-tooth contact zone by 1.5times and to an increase in the temperature in the tooth-blank contact zone.

Optimization of process parameters for minimizing the temperature field of high-speed milling of titanium alloy thin-walled parts

Optimization of process parameters for minimizing the temperature field of high-speed milling of titanium alloy thin-walled parts

Effect of structural parameters on the surface roughness and mechanical properties of Ti-6Al-4 V alloy thin-walled structure fabricated by selective laser melting

Ti-6Al-4 V alloy (Ti64) thin-walled parts with different structural parameters including placement mode, tilt angle (θ), length and thickness were fabricated by selective laser melting (SLM). The effects of structural parameters on the surface roughness and mechanical properties were investigated to provide guidance for optimizing SLM process of thin-walled structures. Firstly, surface roughness on downdip plane is larger than that on updip plane. The thin-walled parts perpendicular to the scraper and increasing θ are beneficial for reducing surface roughness. Secondly, pores size is concentration below 50 μm, and the porosity is concentrated between 0.28% and 1.5%. The porosity shows a decreasing trend with increasing θ. Coarse columnar prior-β-Ti grains are parallel to building direction (BD), which is not affected by θ. α-Ti/β-Ti laths exhibit thickness less than 0.5 μm inside prior-β-Ti grains, and are refined with reducing thickness of the thin-walled parts. Finally, Ti64 thin-walled parts with different structure parameters exhibit relatively stable strength and plasticity, namely tensile strength of 1040–1130 MPa, yield strength of 1015–1145 MPa, and elongation of 7∼8.5%. In summary, placement mode and θ exhibit more significant impact on the final properties of the thin-walled parts, namely, perpendicular to the scraper and increasing θ are beneficial for reducing surface roughness and porosity. While the structural parameters show no significant effect on the mechanical properties.

Machining-induced residual stress and deformation during Mg–Li alloy thin-walled rib-web parts milling

The deformation of thin-walled parts based on the lightweight Mg–Li alloy materials caused by machining-induced stress is an important factor hindering the further development of lightweight in the aerospace field. Prediction of the machining-induced residual stress is the key to understand the deformation and derive low-stress machining scheme. In this study, the equivalent cutting deformation loads were applied to substitute the strongly coupled thermal-mechanical behavior between the tool and part to realize the prediction of the machining-induced stress and deformation of thin-walled rib-web part under different milling conditions. The local regular and complex rib-web parts share a same deformation mode, both behave as in-plane bending deformation of the machined surface. The low-stress milling scheme of up milling combined with cryogenic cooling obtained based on the local regular four rid-web thin-walled part was applicable to the prediction of the complex Mg-Li alloy disk rib-web part. Compared with the initial scheme, the maximum stress and deformation displacement based on the low-stress scheme were reduced from 80 to 36 MPa and from 0.04060 to 0.00814 mm, respectively. Finally, the effectiveness of low-stress milling scheme were verified based on the milling and measurement experiments of the complex thin-walled disk rib-web part. These results indicate the effectiveness of the modeling method for thin-walled rib-web parts and prove the results obtained based on the local model can be extended and applied to large complex parts with the same structural type.

Fabricating large scale titanium alloy thin-walled double-sided part by hot-wire arc additive manufacturing

Using traditional process to fabricate large scale titanium alloy thin-walled part such as wings and grid rudder, has the problem of low material utilization. Wire arc additive manufacturing (WAAM) is a flexible manufacturing technology with high deposition efficiency and high material utilization. In addition, a hot-wire device is attached to the WAAM system as auxiliary heat source, and the WAAM system becomes hot-wire arc additive manufacturing (HWAAM) system. In this paper, a large scale titanium alloy drone frame was fabricated by HWAAM. A double-side alternating deposition method was proposed to reduce the thermal deformation of the substrate. Two additional sections of the drone frame was taken off for mechanical analysis. The shape of the whole drone frame is completed and the mechanical properties meet the requirements of the project.

Investigation on the formability and deformation mechanism of aluminum alloy thin-walled parts at cryogenic temperature

Due to the poor ductility of aluminum alloy sheet at room temperature, which results in the difficulty in forming complex thin-walled parts, a novel forming method for thin-walled parts at cryogenic temperatures is proposed in this research, at which its strength and ductility are significantly improved. In this work, the cryogenic forming tests of the typical aluminum alloy thin-walled part were carried out, the formability and forming quality of the parts were evaluated, and the mechanism of the increase of strength-ductility at cryogenic temperature was discussed. The results of these experiments indicate that compared to room temperature, the formability of 2024-O aluminum alloy sheet at cryogenic temperature is significantly improved; the maximum forming height of aluminum alloy thin-walled part increases by 21.5% to 96 mm at − 180 ℃; in addition, the quality of parts formed at cryogenic temperature is better, whose maximum thinning rate is only half of the corresponding value at room temperature, and the hardness increases by 8.6%. It can be seen from the microstructure that when aluminum alloy deforming at low temperature, the dynamic recovery is restrained, the accumulation of dislocations leads to the increase of resistance to dislocation’s motion. The deformation of aluminum alloy at low temperature is more uniform, the work hardening ability is significantly improved, and its strength and ductility are enhanced. This study proves the feasibility of forming aluminum alloy thin-walled parts at cryogenic temperature, and provides a new idea for high-quality forming of complex thin-walled parts.

Study on the Relationship between Process Parameters and theFormation of GTAW Additive Manufacturing of TC4 Titanium Alloy Using the Response Surface Method

The geometric parameters of the deposited layer include the width, height, and penetration depth of the deposited layer. The welding current, wire feeding speed, and torch travel speed during the additive manufacturing process of TC4 titanium alloy have the greatest impact on the geometric parameters of the deposited layer. In order to study how the deposition layer width, deposition layer height, and penetration depth are affected by the welding current, wire feeding speed, and torch travel speed, this article uses Design Expert 8.0.6 software for Box−Behnken design response surface experiments. During the experimental design, the welding current, wire feeding speed, and torch travel speed are used as input variables. The deposition layer width, deposition layer height, and penetration depth are selected as the responses. We designed 17 response surface experiments that were conducted using GTAW-AM. The results show that as the welding current increases, the penetration depth and width of deposition layer gradually increase, and the deposition layer height gradually decreases. As the wire feeding speed increases, the deposition layer height and penetration depth gradually increase, and the wire feeding speed has a minimal effect on the deposition layer width. As the torch travel speed increases, the penetration depth, width and height of deposition layer gradually decrease. The response surface method experimental design can also optimize the matching of three process parameters: welding current, wire feeding speed, and torch travel speed, thereby obtaining the optimal matching range of process parameters. Within the optimized matching range of process parameters, a welding current of 90 A, a wire feeding speed of 900 mm/min, and a torch travel speed of 200.18 mm/min were selected to prepare TC4 titanium alloy thin-walled part. The microstructure of the top, middle and bottom are all basketweave structure. The α phase gradually becomes coarse from the top to the bottom. The microhardness of the top, middle, and bottom of the thin-walled parts is 362.7 HV, 352.7 HV, and 340.5 HV, respectively. The horizontal tensile strength is 926.1 MPa, with an elongation of 12.22%, and the vertical tensile strength is 938.1 MPa, with an elongation of 14.41%.

Study on milling flatness control method for TC4 titanium alloy thin-walled parts under ice fixation

Thin-walled parts are characterized by weak rigidity and are very prone to deformation during machining, which directly affects the machining accuracy and performance of the parts, so controlling the machining deformation of thin-walled parts is an urgent process problem to be solved. To address such problems, this paper proposes a flatness control machining method based on ice holding of workpieces. The method uses frozen suction cups to solidify liquid water to achieve stress-free clamping of workpieces. We conducted a low-temperature tensile test to investigate the low-temperature mechanical properties of the material. Comparative tests of ice-free and low-temperature ice-fixed milling were conducted to compare and analyze the changes of flatness and milling force in the two working conditions, to investigate the influence of machining parameters on the flatness of thin-walled parts, and to reveal the mechanism of low-temperature milling of ice-fixed workpieces. In addition, the low-temperature milling performance of titanium/aluminum alloy based on ice-fixation was compared. The results show that TC4 has good plasticity, high flexural strength ratio and strong resistance to deformation at low temperatures. Compared with no ice-holding, ice-holding machining effectively improves the flatness of the workpiece, and the order of the machining parameters affecting flatness is: feed rate > milling depth > spindle speed. The milling forces under ice-holding conditions were all greater than those without ice holding. The stiffness and hardness, resistance to damage and deformation of titanium alloy at low temperature are greater than those of aluminum alloy. This method provides a new method for high-precision machining of thin-walled parts.

Milling performance of cryogenic cooled titanium alloy thin-walled parts based on cantilever sheet

Milling performance of cryogenic cooled titanium alloy thin-walled parts based on cantilever sheet

Analysis and Optimization of Milling Deformations of TC4 Alloy Thin-Walled Parts Based on Finite Element Simulations

TC4 (DIN3.7164/5) alloy thin-walled parts are widely used in aviation and aerospace industries. However, due to their special structure, shape and poor machinability, large milling forces and milling deformation often occur in the milling process, which cannot guarantee the machining quality and accuracy. The milling processing parameters and milling geometric parameters have a significant impact on the milling force and the deformation, and optimization of the influence factors of milling deformations is important for milling quality. Considering that performing milling experiments under multiple conditions is often costly and time-consuming, this paper provides a finite-element-simulation-based method to study effects of the factors on the forces and deformations during milling thin-walled parts. Firstly, using ABAQUS, a finite element simulation model of the milling process of thin-walled parts is established. Additionally, an orthogonal experimental scheme is designed for optimization of the milling parameters, so as to determine the optimized experimental scheme, and then the optimized experimental scheme is verified to reduce the milling force and deformation by finite element simulations. The optimal parameters for a minimal milling force are a spindle speed of 2000 r/min, a feed rate per tooth of 0.04 mm/z, a milling depth of 1.6 mm, a milling width of 1 mm, a diameter of 6 mm, a rake angle of 20°, a tilt angle of 45°, and two teeth. Similarly, the optimal parameters for minimal node deformations are a spindle speed of 4800 r/min, a feed rate per tooth of 0.18 mm/z, a milling depth of 1 mm, a milling width of 1 mm, a diameter of 16 mm, a rake angle of 20°, a tilt angle of 40°, and four teeth. In addition, this paper uses an optimization algorithm to fit the empirical function with a certain practical value, which can provide a reference for the machining of TC4 titanium alloy. By doing so, we can optimize the milling parameters to obtain the desired machining quality and accuracy, while also saving on time and resources.

Offline Feed-Rate Scheduling Method for Ti–Al Alloy Blade Finishing Based on a Local Stiffness Estimation Model

In the aerospace field, Ti–Al alloy thin-walled parts, such as blades, generally undergo a large amount of material removal and have a low processing efficiency. Scheduling the feed rate during machining can significantly improve machining efficiency. However, existing feed-rate scheduling methods rarely consider the influence of machining deformation factors and cannot be applied in the finishing stages of thin-walled parts. This study proposes an offline feed-rate scheduling method based on a local stiffness estimation model that can be used to reduce machining errors and improve efficiency in the finishing stage of thin-walled parts. In the proposed method, a predictive model that can rapidly calculate the local stiffness at each cutter location point and a cutting-force prediction model that considers the effect of cutting angle are established. Based on the above model, an offline feed-rate scheduling method that considers machining deformation error constraints is introduced. Finally, an experiment is performed by taking the finishing of actual blade parts as an example. The experimental results demonstrate that the proposed feed-rate scheduling method can improve the machining efficiency of parts while ensuring machining accuracy. The proposed method can also be conveniently applied to feed-rate scheduling in the finishing stage of other thin-walled parts without being limited by machine tools.

High surface quality additive manufacturing process of titanium alloy with composite heat source

In order to solve the problems of high surface roughness and low dimensional accuracy of titanium alloy metal-wire fuse additive manufacturing, this paper proposes a high surface quality and dimensional accuracy of titanium alloy additive manufacturing with composite heat source process. On the basis of orthogonal experiments, titanium alloy wires with diameter of 0.3 mm Ti-6Al-4V were deposited in a small molten pool by laser and Joule heat source. Thin-walled titanium alloy parts with high surface quality and dimensional accuracy were obtained, and the quality, microstructure, and mechanical properties were tested. The measurement areas are shown that the average roughness Ra is 1.65 μm in the direction deposition, and the dimensional accuracy error is less than 0.28 mm. On this basis, the microstructure and mechanical properties of titanium alloy thin-walled were analyzed. The microstructures are net-like, with microhardness of about 330HV. The ultimate tensile strength of titanium alloy thin-walled parts is 917.56 MPa, and the elongation can reach 20.68%, which is comparable to the strength of casting and forging fracture. The results show that the proposed additive manufacturing process of metal-wire with composite heat source has the potential of further metal AM in high surface quality parts.

Side-Milling-Force Model Considering Tool Runout and Workpiece Deformation

With the development of Industry 4.0, hard-cut materials such as titanium alloys have been widely used in the aerospace industry. However, due to the poor rigidity of titanium alloy parts, deformation and vibration easily occur during the cutting process, which affects the accuracy, surface quality and efficiency of part machining. Therefore, in this paper, tool runout and workpiece deformation are introduced into the milling process of flat-end mills. Based on the tool’s hypocycloid motion, a geometric parameter model of the milling process is established, and the undeformed cutting thickness model is obtained considering the tool runout and workpiece deformation. Finally, the milling force model for side-milling titanium alloy thin-walled parts was established. The accuracy of the force model is verified through experiments. The error of the proposed model is far less than that of the traditional basic method. The maximum error of the traditional basic method is 87.09%. However, the maximum error of the proposed model is only 66.54%. The results show that the proposed force model considering tool runout and workpiece deformation can provide more accurate milling force prediction.

Machinability analysis of micro-milling thin-walled Ti-6Al-4V micro parts under dry, lubrication, and chatter mitigation conditions

Micro-milling technology is an efficient method for machining titanium alloy thin-walled micro parts. However, the machinability of thin-walled microstructures can be greatly affected by chatters due to their weak stiffness, especially in difficult-to-machine materials like titanium alloys. In order to obtain high-quality thin-walled micro parts, a chatter mitigation strategy is presented and its mechanism is analyzed in this paper. The titanium alloy workpiece is submerged into a kind of high-viscosity fluid, which can improve machining stability by increasing the damping of the micro-milling process. The stability lobe diagrams (SLD) are established, and the machinability is analyzed and compared under different machining conditions. The cutting force, surface roughness, micro-tool wear, and dimension accuracy of thin-walled micro parts are selected as the evaluation criteria for the machinability assessment. Well-designed micro-milling experiments are carried out under dry, lubrication, and chatter mitigation conditions using the same cutting process parameters. The results show that the use of cutting fluid can effectively improve machinability under stable cutting processes, but the effect of cutting fluid is weakened under chatter machining. The proposed chatter mitigation strategy can suppress regenerative chatter throughout the micro-milling process for thin-walled micro parts and improve their machinability comprehensively.

Finite Element Simulation of Bending Thin-Walled Parts and Optimization of Cutting Parameters

Aiming at the problems of large elastic deformation and low machining accuracy in cutting titanium alloy thin-walled parts, this paper establishes the finite element model of milling titanium alloy thin-walled parts, and simulates and analyses the milling process of titanium alloy thin-walled parts by the statics analysis module of ANSYS 15.0 software. The maximum deformation point of the workpiece in the milling process is determined. Then the combination of cutting parameters that can minimize the deformation is determined by the orthogonal experiments of four factors and four levels. This paper designs the single factor experiments, which study the distribution of the milling force and the deformation law of the parts in the milling process. Moreover, this paper carries out the optimal design of the cutting parameters by orthogonal experiments, which provides a reference for the selection of the cutting parameters for the bending thin-walled parts of titanium alloy.

Milling chatter detection of thin-walled parts based on GA-SE-SCK-VMD and RCMDE

In the milling process, it is easy to produce chatter due to the low rigidity of the thin-walled structure, which leads to the deterioration of workpiece surface quality and reduces the service life of cutting tools and machine tools. Therefore, a new chatter detection method for thin-walled parts based on optimal variational mode decomposition (OVMD) and refined composite multi-scale dispersion entropy (RCMDE) is proposed in this paper. Firstly, to solve the problem that the decomposition effect of the variational mode decomposition (VMD) algorithm is greatly affected by its parameter, a genetic algorithm (GA) is used to iteratively optimize the parameter of the VMD algorithm, and a new index, square envelope spectral correlated kurtosis (SE-SCK), is introduced as the fitness function of the genetic algorithm. Then, the energy ratio of the decomposed signal is calculated as the principle of selecting sub-components, and the sub-components with rich chatter information are selected for signal reconstruction. To solve the problem that the multi-scale dispersion entropy (MDE) will miss some information in the multi-scale process, RCMDE is introduced to detect milling chatter. Finally, the experiment of the variable cutting depth in side milling of titanium alloy thin-walled parts is carried out. The experimental results show that the OVMD algorithm proposed can solve the problem of difficult separation of chatter frequency bands caused by mode aliasing and lay a foundation for subsequent chatter feature extraction. RCMDE is more conducive to chatter detection than the single-scale DE when the scale factor is 4. The distinguishing effect of RCMDE on the machining state is more than 50% higher than that of MDE when the scale factor is 4.

Investigation on an in-process chatter detection strategy for micro-milling titanium alloy thin-walled parts and its implementation perspectives

Thin-walled micro parts are widely used in many fields, such as aviation, aerospace, precision engineering, and even micro-molds. Compared with other micro-fabrication technology, micro-milling can be considered as one of the most efficient 3D fabrication techniques. However, due to the vulnerable stiffness of thin-walled micro parts and micro tools, regenerative chatter is prone to occur during the micro-milling process. Severe chatter can lead to large fluctuations in cutting forces, resulting in deterioration of surface roughness/integrity and decreasing in tool life. Therefore, an in-process chatter detection strategy based on the feature extraction of micro-milling forces is proposed in this paper. Micro-milling force signals are measured and processed by advanced algorithms developed. After variational mode decomposition (VMD) for each group of cutting forces, the optimal intrinsic mode function (IMF) is adopted based on the Laplacian score (LS). The multi-scale permutation entropy (MSPE) values of the optimal IMF of each group are calculated, wherein the scale factor s, the embedding dimension m, and the delay time t are obtained by the genetic algorithm (GA). The obtained MSPE values are used as input vectors to train the support vector machine (SVM) classifier, which is used to monitor the stability states of the micro-milling processes. The effectiveness of the proposed strategy is compared with the other classic chatter detection methods and indicators in the micro-milling experiments of thin-walled parts. The results show that the method resulted from the strategy can extract cutting force features effectively and in-process detect chatters accurately in micro-milling thin-walled parts processes.

Mcdm WASPA in a Neutrosophic Environment Applied to Optimization of the Parameters for Minimization of Surface Roughness and Machining Deformation in Milling of Al Alloy Thin Walled Parts.

The following research shows a methodology that combines the multicriteria method WASPAS and Neutrosophic, which seeks to improve decision making within the planning processes in machine shops. With WASPAS the best alternative is selected and Neutrosophic offers us the advantage of driving the concept of uncertainties and neutralities, and with it the values of the input variables for high speed machining to manufacture the rectangular piece of aluminum alloy 5083. With the evaluation of the criteria, when applying the method it is obtained as objective that the alternative ten is the best, therefore, when implementing the input parameters: S = 15000 rpm, doc= 0.10 mm, ts= 3.0 mm, F= 3600 m/min, the surface quality and low deformation of the part is guaranteed. It is concluded that the WASPAS multicriteria analysis method with neutrosophy is an excellent tool, with a low cost and good reliability, as a solution to be applied in machining shops to improve decision making in process planning processes from the optimal selection of machining parameters.

Surface finishing method based on laser re-melting using a cone annular beam for additive manufacturing

In this paper, a novel surface finishing method of cone annular beam laser re-melting (CALR) is proposed which aims at optimizing the side surface quality of AlSi10Mg parts produced by directed energy deposition. Meanwhile, a feature-based characterization method was conducted to realize the multiscale analysis of the topographic features. The results show that the developed CALR is a powerful tool which can greatly reduce the surface roughness: the final optimal aluminum alloy thin-walled parts with a roughness of 7.1 µm was obtained, which was 68.3% less than the original roughness of 22.4 µm without the implementation of CALR. The optimization mechanism reveals the roughness reduction was mainly attributed to the elimination of the stair-step effect, while the role of powder particle features was much less significant on roughness reduction of the overall surface. The CALR method together with the feature-based surface characterization provides an innovative solution for side surface quality optimization for laser additive manufacturing.

Microstructural evolution and mechanical properties of 2219 aluminum alloy from different aging treatments to subsequent electromagnetic forming

The manufacturing process of 2219 aluminum alloy (AA2219) thin-walled parts nowadays exhibits challenging to meet the service requirements of the high performance and lightweight new-generation launch vehicle. This work employs different aging treatments and subsequent electromagnetic forming to investigate the microstructure evolution and mechanical properties of AA2219. The results show that the optimal single aging treatment is 180 °C for 6 h, and the optimal double aging treatment through L 16 (4 4 ) orthogonal experimental is 140 °C for 2 h + 180 °C for 6 h. Meanwhile, the precipitated phase of single aging is mainly θ″ phase with a three-layer Cu atomic structure while double aging is mainly θ″ phase with a two-layer Cu atomic structure and GP zones. The average thickness and size of θ″ phase and GP zones in the double aged sample are smaller than that of θ″ phase in the single aged sample. However, it has a higher number density and more concentrated size distribution. The plasticity of aged AA2219 improved obviously under the electromagnetic forming. Besides, the forming performance of double aged sample is better with the tensile strength after electromagnetic forming is 424.0 MPa, and the total strain is 25.75%. Electromagnetic forming has negligible effects on the morphology, size, and distribution of precipitated phase. Nevertheless, some dislocations sheared θ″ phase along the {111}<110> slip system under tensile loading. The interaction mechanism of dislocation with different precipitated phases during electromagnetic forming was depicted. This work provides guidance for the strengthening treatment and forming process of AA2219 high-performance parts. • The morphology, size, and distribution of the precipitated phase were investigated. • The plasticity of aged 2219 aluminum alloy improved obviously under the electromagnetic forming. • The interaction mechanisms of dislocation with precipitated phase were depicted.