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According to the weak rigidity and complex structure of aerospace thin-walled parts, an auxiliary support method based on magnetorheological fluid, a dynamic model, and a simulation prediction model are proposed. In this paper, the magnetic field distribution in the space of magnetorheological fluid fixture is simulated, analyzed, and measured. The...
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... According to the characteristics of whether the support position changes during tool feed, the fixtures and devices can be divided into fixed type [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] and movable type [20][21][22][23][24][25][26][27][28][29][30][31]. Fixed fixtures and devices can be used to reduce deformation and vibration by enhancing the stiffness of thin-walled parts. ...
... For instance, Wang et al. [13] submerged thin-walled cavity parts in a corn starch suspension to suppress chatter and forced vibration in accordance with the property that non-Newtonian fluids exhibit solid-like state when subjected to high disturbance forces. Similarly, Ma et al. [14] and Jiang et al. [15] designed a magnetorheological fluid (MRF) flexible fixture to suppress vibration in machining based on the characteristic that magnetorheological fluid transforms into a solid under the action of a magnetic field. Considering the effect of mechanical composite clamping on the previous MRF flexible fixture, Guo et al. [16] effectively suppressed the chatter of thin-walled workpieces and enhanced the surface quality However, these fixtures and devices are difficult to design and expensive to prepare for machining large thin-walled parts. ...
Large thin-walled workpieces have large deformation and vibration during end milling due to their weak rigidity, which can lead to degradation of the surface quality of workpiece. To this end, this paper proposes a new method to suppress vibration and deformation during mirror milling of thin-walled workpieces by using a magnetic follow-up support fixture. The main idea is to design a fixture that can clamp around the milling area of the workpiece in real time, follow the tool motion and continuously provide a controlled air pressure force to the opposite side of the milling area without providing the mirroring support fixture that occupies a large space to the opposite side of workpiece. First, to accurately characterize the motion of the fixture, a mathematical model of the axial magnetic force considering the lateral offset is developed. On this basis, to efficiently investigate the capability of the fixture in improving the dynamic characteristics and dynamic response of workpiece, the finite element method (FEM) is used to analyze the frequency response functions (FRF) and the mode shapes of workpiece under the action of the fixture. Then, the vibration amplitude and deformation of workpiece on the milling path are simulated and studied by considering the variation of the air pressure and the position of the fixture. Finally, the prototype of the fixture is developed and then the effectiveness and feasibility of the proposed method are verified under the experimental tests with different machining parameters.
... On the other hand, elastic thin-walled workpieces are typical flexible structures, and their vibration control has always been the focus of attention. There has been a lot of research on the vibration control of flexible structures, the most representative of which is the active control strategy based on intelligent materials, such as piezoelectric intelligent actuators [44][45][46], magnetorheological intelligent actuators [47,48], etc. In this case, the flexible structure becomes an intelligent structural system. ...
... Based on the dynamic coupling effect between the grinding spindle and the thin-walled workpiece, this paper attempts to realize On the other hand, elastic thin-walled workpieces are typical flexible structures, and their vibration control has always been the focus of attention. There has been a lot of research on the vibration control of flexible structures, the most representative of which is the active control strategy based on intelligent materials, such as piezoelectric intelligent actuators [44][45][46], magnetorheological intelligent actuators [47,48], etc. In this case, the flexible structure becomes an intelligent structural system. ...
The robotic grinding system for a thin-walled workpiece is a multi-dimensional coupling system composed of a robot, a grinding spindle and the thin-walled workpiece. In the grinding process, a dynamic coupling effect is generated, while the thin-walled workpiece stimulates elastic vibration; the grinding spindle, as an electromechanical coupling actuator, is sensitive to the elastic vibration in the form of load fluctuations. It is necessary to investigate the electromechanical coupling dynamic characteristics under the vibration coupling of the thin-walled workpiece as well as the vibration control of the robotic grinding system. Firstly, considering the dynamic coupling effect between the grinding spindle and thin-walled workpiece, a dynamic model of the grinding spindle and thin-walled workpiece coupling system is established. Secondly, based on this established coupling dynamic model, the vibration characteristics of the thin-walled workpiece and the electromechanical coupling dynamic characteristics of the grinding spindle are investigated. Finally, a speed adaptive control system for the grinding spindle is designed based on a fuzzy PI controller, which can achieve a stable speed for the grinding spindle under vibration coupling and has a certain suppression effect on the elastic vibration of the thin-walled workpiece at the same time.
... In the research of workpiece vibration reduction, strategies such as fixtures and auxiliary supports are mostly designed for specific workpieces [17,18]. Jiang et al. [19] proposed an auxiliary support method based on magnetorheological fluid, which effectively reduced the machining vibration of thin-walled aerospace parts and improved the machining quality. Although this type of method has a pleasurable vibration reduction effect, it depends on the specific workpiece material and structure and is not universal. ...
In the process of aeroengine blade grinding, the vibration of the robot reduces the precision of grinding force control at the end, which seriously affects the processing quality of the blade. Thus, a macro–micro grinding system composed of a robot and a pneumatic end-effector is constructed. The system is controlled by the robot to realize the position and the end-effector to realize the force control. Based on a simplified model of the robot and the end-effector, a force compensation strategy combining a dynamic matrix prediction algorithm and an impedance compensation method is proposed. The axial grinding force and vibration compensation force are rolling optimized in a limited time domain in a way of minimizing the quadratic performance index, the time lag of the force compensation process and the uncertainty of model parameters are compensated, and the grinding force can be tracked stably is realized. The simulation and experimental results indicate that the method can quickly suppress the vibration, decrease the force fluctuation, and improve the blade grinding quality.
... Additive byproducts such as spatter from wire-arc or unmelted powder from blown powder would likely contaminate the wax and limit reusability as well. Taking this concept further, Jiang et al. [22] used magnetorheological fluid in a magnetic field as a damping medium. The part was fixtured in a container and the fluid was poured around the part and solidified. ...
Thin-walled features can be difficult to produce with traditional machining methods which often rely on excess stock material for stiffness. This challenge is increased in hybrid manufacturing where the feature is already near net shape before machining. Significant workpiece deflection can result in poor geometric and surface finish tolerances on the finished part. A potential solution to this problem is to implement sacrificial support structures to the as-printed geometry. The supports are then machined away during the finishing portion of the hybrid process. In the present work, several different design parameters for these sacrificial supports were evaluated to determine their impact on the quality of representative thin wall geometry samples. The angle, height, and spacing of triangular support structures were varied for each sample and then machined and examined. The addition of these supports relative to an unsupported configuration provided a deflection reduction of around 0.2 mm. Surface roughness was improved by approximately 1.5 µm. Increasing values of support height were found to correspond to reduced wall deflection. Similarly, decreasing values of support angle and support spacing improved geometric accuracy. Efficiency comparisons showed that increases in print time corresponded to rapidly diminishing gains in geometric accuracy but continued to improve surface roughness. Implications for hybrid finishing of additively manufactured thin-walled structures is briefly discussed.
... Kim et al. 24 considered a damping force model based on flow mode devices and calculated the corresponding model coefficients. Zhao et al. 25 proposed the dynamic model of MR fixture clamping the workpiece to study the optimal parameters of MR fixture. Ma et al. 26 established a flexible fixture based on the MR fluids to research the vibration suppression during milling the thin-walled part. ...
... The solid particles in magnetorheological fluid are uniform ferromagnetic particles. Assuming that the magnetic current region is Ω, which composed of non-magnetic carrier liquid and N spherical ferromagnetic particlesΩ 1 ，Ω 2 ， … ，Ω n , Under the action of external static magnetic field, Maxwell's basic equations can be expressed 25 : ...
Aerospace thin-walled parts have the characteristics of low stiffness and complex structure, which are easily deformed by machine tool vibration, cutting force and heat during machining. The traditional fixture is in point contact with the workpiece, and the workpiece bears uneven force, which results in poor surface quality and low precision of the part. Therefore, it is urgent to improve the machining efficiency and surface quality of workpiece. According to the performance of magnetorheological fluid, a magnetorheological flexible fixture is designed to completely wrap the parts so as to make them bear uniform force, improve the stiffness of the system and inhibit flutter. Firstly, the stiffness distribution of thin-walled parts, flexible fixtures and fixture-workpiece system is studied in this paper. It can be seen that the symmetrical center stiffness of magnetorheological flexible fixtures is relatively low. Through milling experiments with single process parameters, it is found that when the rotational speed, cutting depth and feed speed change, the composite clamping effect is better than the traditional clamping effect, in which with the increase of rotational speed, the vibration acceleration in Ax, Ay and Az directions decreases by 25.16%, 26.87% and 10.78% respectively; When the cutting depth increases, Ay decreases by 23.12% at the maximum. When the feed speed changes, it decreases by 15.78%. Finally, based on the case of milling thin-walled parts with magnetorheological flexible fixture, it is obtained that the coaxiality of composite clamped thin-walled parts decreases by 13.85%, and the maximum decrease of cylindricity is 36.73%. Roughness value Rz decreases by 80.47% at the maximum. In summary, the above results have verified that the machining quality of the magnetorheological flexible fixture is better.
... Magnetorheological fluid (MRF) with milliseconds rheological phenomenon and flexible magnetic field controllability has been widely used in the modern precision machining field (Elsaady et al., 2020;Kulandaivel and Kumar, 2020;Nugroho et al., 2020). Based on the transferable and adjustable liquid-colloid state, MRF has unique application advantages in the development of machining auxiliary equipment (Jiang X. H. et al., 2020;Saleh et al., 2020;Lv et al., 2021) and surface polishing equipment (Kumar et al., 2019;Nagdeve et al., 2019;Dubey and Sidpara, 2021;Gupta et al., 2021). Therefore, to improve product technology and reduce cost, the research of new MRF equipment has become an important direction in the field of mechanical machining (Wang and Meng, 2001;Park et al., 2007;Bedi and Singh, 2016;Liu Z. et al., 2020). ...
... The method can decrease cutting force and improve the accuracy of thinwalled parts by carrying out milling experiments. Moreover, to investigate the effects of vibration on thin-walled workpiece in machining, Jiang X. H. et al. (2020) established a dynamic model based on the Rayleigh damping matrix and the equivalent force principle and proposed an auxiliary support method with MRF. In this method, based on traditional MRF fixture structure, magnetic field distribution is optimized, and the damping force of the workpiece is deduced. ...
Owing to some of its specific advantages, magnetorheological fluid (MRF) has drawn significant attention in a broad range of modern precision machining fields. With the diversification and increase in demand, many novel structural configurations and processing methods have been applied to mechanical machining equipment. Although different applications using MRF have been proposed in the existing literature, the classification, latest approaches, and further trend are not understood clearly for the machining field. Therefore, the current applications such as machining auxiliary equipment and surface polishing equipment that used MRF are summarized from 2016 to 2020, in this article. Especially, some detailed structures of equipment are investigated, and relative limitations are analyzed based on the characteristics of MRF. Finally, in view of the current equipment, advantages and defects are briefly reported; the developing trends of modern precision machining with MRF are discussed. Therefore, in the state-of-the-art review, the significant role of MRF in the machining field is emphasized, which paves the way to innovative development and market selection.
... The vibration control system considers the FRF characteristics and the time delay effect of the control system, and the feasibility of using piezoelectric plate as active damping to increase the damping of the workpiece and improve the stability of the milling system is proved by experiments. Jiang et al. [6] proposed a magnetorheological fluid auxiliary support method to realize the vibration suppression of complex thin-walled workpiece. Kim et al. [7] proposed a vibration control method for hybrid suspended flexible beam structure composed of elastomeric rubber and piezoelectric laminated actuators. ...
In view of the time-varying dynamic characteristics of thin-walled milling, an optimization method of thin-walled milling control parameters based on the ANFIS system is proposed. Firstly, the control system strategy design and equipment selection construction were carried out, and the fuzzy inference model was built based on matlab platform; Subsequently, the fuzzy inference model of the thin-walled workpiece milling process was obtained by collecting fuzzy inference training data set of and the ANFIS system training. The proportional control coefficient of the controller was optimized based on the input and output relation of the model. Finally, the dynamic response and surface roughness of the controlled thin-walled panel milling process before and after optimization were obtained through cutting experiments, and the effectiveness of the ANFIS method to optimize the control parameters and the reliability of the fuzzy reasoning model were verified through analysis of the reasoning results. The results show that the ANFIS system can predict the vibration response performance of the target by setting the input and output reasonably, and optimize the related variable parameters according to the predicted results, so as to make the thin-wall milling system more stable.
... Wan et al. [23] analysed the effect of fixture layout on the dynamic response of thin-wall multi-framed workpiece(TMW) during machining. Jiang et al. [24] proposed a new type of magnetorheological fluid auxiliary support fixture for the weak rigidity of thin-walled aviation parts and analysed the influence of magnetorheological fluid volume and magnetic field strength on machining vibration. Yang et al. [25] proposed using the resistance of machining vibration to the workpiece to suppress the vibration, and experiments showed that the milling stability was increased by more than 2 times. ...
The casing is a basal body part for assembling other parts in an aeroengine, but its weak rigidity seriously affects machining accuracy and production efficiency. Therefore, it is very important to improve this rigidity of the part during processing. An aeroengine combustor casing is used to study the vibration law and suppression method of a casing milling process through a combination of simulations and physical experiments in this paper. First, the milling vibration law of a Rolls-Royce aeroengine combustor casing is analysed through mechanical analysis and machining vibration detection, and then a simulation experiment environment based on physical experiment verification is established. Second, based on a virtual experimental platform, the free mode and constraint mode of the casing without auxiliary support, multipoint rigid auxiliary support, and flexible surface auxiliary support schemes are analysed. Subsequently, to determine the optimal support pressure for different types of casing parts produced on-site, after analysing the common size range of the casing, 34 and 43 full-factor simulation experiments are performed, and the influence of each factor on the change in vibration is summarised. Finally, a static load experiment is used to verify that the clamping scheme of the flexible surface auxiliary support can improve the radial rigidity of the casing. Through the experimental research in this paper, the results show that the error between the simulation experiment results and the physical experiment is basically kept within 20%, and the established virtual experiment is reliable. At the same time, based on the simulation data in this paper, the function expressions of vibration deformation and support pressure, milling force, case thickness, and casing diameter are fitted, and the R-square reaches 91.2%. This empirical formula provides theoretical support for the selection of optimal support air pressure and the prediction of vibration and deformation.
... However, multiple sensors, signal acquisition and processing system, and other auxiliary devices are required, which hinder the wide application of chatter detection. On the other hand, the active control method becomes increasingly important in the field of chatter control thanks to its efficiency and flexibility [11]- [14]. Accordingly, many active devices are designed, such as electromagnetic actuator [12], piezoelectric actuator [13], and magnetorheological fixture [14]. ...
... On the other hand, the active control method becomes increasingly important in the field of chatter control thanks to its efficiency and flexibility [11]- [14]. Accordingly, many active devices are designed, such as electromagnetic actuator [12], piezoelectric actuator [13], and magnetorheological fixture [14]. However, these devices usually need the relative elements of monitoring, identification and execution, which make this method complex and costly. ...
... According to Eqs. (14) and (18), the relations among the modal characteristics of the damping cutter, its geometrical dimension and material property are shown in Fig. 5, where the toolholder section with the diameter of 70 mm is selected. When h increases, i.e. increasing the diameter of damping core, the stiffness gradually decreases, whereas the loss factor is remarkably enhanced. ...
In order to machine complex box and shell structures, the cutter with large ratio of length to diameter is usually used, whereas the low rigidity of the cutter hinders the increase of the stable machining parameters. This article develops one kind of damping cutter to improve the stable processing condition in this milling operation. The influences of modal characteristic of the cutter on chatter stability are investigated, where it is proven that increasing the dynamic stiffness can efficiently extend the stable zone. On this basis, two damping cutters are designed by inlaying the strips and damping core into the toolholder body. The influences of geometrical parameters and material property of the damping cutters on modal characteristics are theoretically analyzed, and the optimal geometrical dimensions are determined using the finite element simulation. Then, the two damping cutters are fabricated. After modal tests and milling machining experiments, the measured results validate the effectiveness of the developed damping cutters in terms of improvement of the stability frontier.
