Advances in Manufacturing最新文献

In this study, a novel approach for nonlinear process identification via neural fuzzy-based Hammerstein-Wiener model with process disturbance by means of multi-signal processing is presented. The Hammerstein-Wiener model consists of three blocks where a dynamic linear block is sandwiched between two static nonlinear blocks. Multi-signal sources are designed for achieving identification separation of the Hammerstein-Wiener process. The correlation analysis theory is utilized for estimating unknown parameters of output nonlinearity and linear block using separable signals, thus the interference of process disturbance is solved. Furthermore, the immeasurable intermediate variable and immeasurable noise term in identification model is taken over by auxiliary model output and estimate residuals, and then auxiliary model-based recursive extended least squares parameter estimation algorithm is derived to calculate parameters of the input nonlinearity and noise model. Finally, convergence analysis of the suggested identification scheme is derived using stochastic process theory. The simulation results indicate that proposed identification approach yields high identification accuracy and has good robustness.

Angular rolling technology can overcome the size limitation of plate mill equipment and product heavy steel plate with large unit weight or improve the production efficiency of small width spreading ratio product. With the DEFORM software, the numerical simulation study of the angular rolling process was carried out, and the relation laws of the width, rolling force and strain of the rolled piece under different angular rolling process conditions were obtained. The simulation results show that with the rotation angle increasing, the width of the rolled piece increases. Comparing with the conventional rolling process, the rolling force changes gradually during the biting and throwing stage of the angular rolling pass. With the rotation angle increasing, both the equivalent strains in the thickness direction and in the width direction gradually increase. According to the pattern and dimension’s changing formula in the double-pass angular rolling process, the prediction model of angle, reduction and width spreading is built. The opening value of side guide is set for the rotation angle controlling. For one 5 000 mm heavy plate mill, the automation control system was modified, and the angular rolling technology was applied online. The absolute deviation of target width does not exceed ± 20 mm and the relative deviation does not exceed 1%. The large unit weight plate that cannot be rolled with traditional process, can be produced now, and the annual output increases by 10 000 t.

Although incremental sheet forming (ISF) is an efficient way to manufacture customized parts, the forming performance and geometric accuracy of formed parts need to be improved to meet industrial application. One feasible solution for these problems is to adopt proper heat treatment strategies for the sheet material both before and during the forming process. In this paper, the effects of heat treatment before forming and heat-assisted forming on the formability and performance of formed parts were experimentally investigated. First, TA1 sheets were heat-treated at different temperatures before forming, and then the sheets were incrementally formed into the target shape with variable angles at different temperatures. After heat treatment, the strength of sheets was decreased due to the occurrence of recrystallization and the growth of grains. Meanwhile, the surface quality of formed parts was also improved with pre-heat treatment before forming. During the heat-assisted forming process, the sheet was softened and the deformation resistance was reduced with the increase of temperature. Therefore, the axial forming force was decreased obviously and the formability of the sheet was increased obviously. Furthermore, by adopting both heat treatment and heat-assisted forming, it was found that the forming force could be further reduced and the formability of the sheet and surface quality could be further improved. As for geometric accuracy, heat treatment has a good effect on improving it, while heat-assisted forming has adverse effect. These findings provide an effective heat treatment strategy for improving the geometric accuracy and surface quality of the incrementally formed parts with lower forming force.

Zero defection manufacturing (ZDM) is the pursuit of the manufacturing industry. However, there is a lack of the implementation method of ZDM in the multi-stage manufacturing process (MMP). Implementing ZDM and controlling product quality in MMP remains an urgent problem in intelligent manufacturing. A novel predict-prevention quality control method in MMP towards ZDM is proposed, including quality characteristics monitoring, key quality characteristics prediction, and assembly quality optimization. The stability of the quality characteristics is detected by analyzing the distribution of quality characteristics. By considering the correlations between different quality characteristics, a deep supervised long-short term memory (SLSTM) prediction network is built for time series prediction of quality characteristics. A long-short term memory-genetic algorithm (LSTM-GA) network is proposed to optimize the assembly quality. By utilizing the proposed quality control method in MMP, unqualified products can be avoided, and ZDM of MMP is implemented. Extensive empirical evaluations on the MMP of compressors validate the applicability and practicability of the proposed method.

Impact hydroforming (IHF), as a novel sheet metal forming technology with the advantages of high strain rate forming and flexible liquid loading, is highly suitable for efficiently manufacturing aluminum complex-shaped sheet parts. In this paper, deformation characteristics of complex sheet parts under IHF are systematically investigated. The mechanical properties of 2024 aluminum alloy under a wide range of strain rates (10⁻³ s⁻¹–3.3×10³ s⁻¹) were studied. It indicated that the elongation of 2024 aluminum alloy was improved by 116.01% under strain rates of 3.306 × 10³ s⁻¹, referring to 10⁻³ s⁻¹. Further, a complex-shaped part with symmetrical and asymmetrical structures was selected. The deformation characteristics of sheet and role of inertial effect under IHF were investigated with well-developed solid–liquid coupling finite element (SLC-FE) model with high accuracy. Differentiating deformation tendency is found for symmetrical structure with notably prior deformation at central zone, showing a “bulging” profile at initial forming stage. Whereas, synchronous deformation is presented for asymmetrical structure with a “flat” profile. Additionally, distinctive inertial effect was observed at different positions change for both symmetrical and asymmetrical structures, in which lower values were resulted at their central regions. Meanwhile, the inertial effect evolved with the impacting speed. Specially, larger difference of inertial effect was observed with increasing impacting speed.

Low-temperature silicon nitride (SiN_x) films deposited by plasma-enhanced chemical vapor deposition (PECVD) have huge application potential in the flexible display. However, the applicability of SiN_x largely depends on the film’s general properties, including flexibility, deposition rate, residual stress, elastic modulus, fracture strain, dielectric constant, refraction index, etc. Process optimization towards specific application by conventional experiment design needs lots of work due to the interaction of muti quality and process parameters. Therefore, an efficient global optimization approach for the process technology was proposed based on the Taguchi orthogonal experiment method considering muti-factor muti-responses. First of all, the Taguchi orthogonal experiment design and analysis was used to rank the influences of main process parameters on the quality characteristics, including radio frequency (RF) power, pressure, silane flow rate, ammonia flow rate and nitrogen flow rate. Then, the global optimization approach was carried out utilizing the multi-response optimizer considering the combination target of film formation rate, residual stress, dielectric constant, elastic modulus, fracture strain, refractive index. Finally, the optimal solution of the SiN_x film was finally obtained and verified.

During assembly process, the miniature part needs to be fixed in its assembly position. In some occasions where adhesive is used, the joining force is not established due to the adhesive curing process, in that case the locking of parts is required. Manual locking is difficult to meet the increasing demand for mass production. To solve this problem and realize fully automatic assembly, a novel gripper module was designed and corresponding locking method was proposed. Thanks to the functional integration, the gripper module is capable of manipulating and locking the part. This module is integrated into the assembly system and plays a crucial role in automatic assembly. The locking method for automatic assembly is based on the integration of the part picking up and the locking unit releasing. After being placed accurately at its desired position, the miniature part can be automatically locked by releasing the locking unit. The innovative structure and mechanism of the gripper module convert the spring force into the locking force of the miniature part, ensuring non-rigid locking and suitable small locking force. Locking principle, flexibility and limitations of the proposed method were clarified in detail. Moreover, an effective compensation strategy was used to achieve accurate and stable pickup of the part, which increased the reliability of the assembly process. During automatic locking, the disturbances to the part due to the eccentric load were analyzed. The effectiveness of the gripper module and proposed method was verified by experiment. Experimental results indicated that the modular system integrated with the gripper module could meet the requirements of fully automatic assembly. Manual locking is replaced by automatic locking, and workers are liberated from tedious manual operations. The improvement of automation level enables assembly equipment to be applied to mass production scenarios.

Many factors affect the integrity of precision ball bearings. In this study, the multi-dimensional controllability of precision ball bearings produced in different company brands (bearing A and bearing B) were studied and compared. The geometric errors (flatness, parallelism, roundness and cylindricity of inner and outer rings, roundness, groove and roughness of inner and outer rings) and vibration errors of bearings were analyzed. Concurrently, the residual stress, residual austenite content, element content ratio, metamorphic layer and temperature-vibration displacement coupling test were also analyzed. Based on the above analysis conclusion, the bearing fatigue life test was carried out for 2 150 h. The reliability of the conclusion is proved again as follows. When the residual austenite content in the raceway of precision ball bearing is 10%, the axial residual stress is 877.4 MPa; the tangential residual stress is 488.1 MPa; the carbon content is 6%; the test temperature of bearing is the lowest; and the service life is prolonged.

An urgent demand for lowering bonding temperature has been put forward by advanced flip-chip integration such as micro-LED packaging and heterogeneous integration of semiconductor devices. Indium microbump with low-melting point has attracted attention for its potential use as the interconnection intermediate, and the development of its fabrication process is therefore of great attraction. To reveal the critical process factors for successfully fabricating a high-density In microbump array, this paper investigated a simple process flow of In patterning and reflow and detailed the flux-assisted wet reflow process. Critical process conditions, including the patterned In volume, alignment accuracy, reflow reagent liquidity, and temperature profile, were described, with a particular emphasis on the role of surface tension of molten indium film during the formation of spherical microbumps. A high-density indium ball array with an overall yield greater than 99.7% can be obtained, which suggests that the In patterning and wet-reflow processes are robust and that a high-quality microbump array could be readily formed with low equipment requirements. Furthermore, the interfacial reaction characteristics between In microbump and Au adhesion layer were investigated under thermal aging conditions, which revealed lateral intermetallic growth of AuIn₂ compound and well-retained interfacial strength even after prolonged aging.

In this paper, the system on display panel (SoDP) architecture, the primary stage of heterogeneous integration system in display (HiSID), is introduced for the first time. In this architecture, the driving components of display, which are supposed to be on the display flexible print circuit (FPC) in traditional architecture, are innovatively integrated onto the backside of display panel. Through the SoDP architecture, the simulated impact strain in the panel fan-out region can decrease about 30% compared to the traditional architecture, and SoDP provides more the 10 mm extra space in the in-plane Y-direction for holding a larger battery. Also, the SoDP is compatible with the current organic laser emitted diode (OLED) and system in package (SiP) processes. Besides the primary stage, this paper also presents a comprehensive and extensive analysis on the challenges of the manufacturability for the advanced stage of HiSID from four key technologies perspectives: device miniaturization, massive manufacturing, driving technology, and advanced heterogeneous integration.