Carbon fiber-reinforced polymer (CFRP) is a multiphase material consisting of fibers, interfaces, and matrix. Due to their excellent mechanical properties, they are widely used in the energy, military, and aerospace sectors. However, due to the anisotropic and non-homogeneous nature of the material, tool wear inevitably occurs during machining. In order to ensure the quality of material machining and to control tool costs, tool condition monitoring has become an integral part of machining. By monitoring the tool condition in machining, predictive maintenance can be achieved, and early warning of tool failure can be achieved, thus drastically reducing downtime and saving costs in terms of time and labor. On this basis, this paper proposes a novel physics-guided neural network approach for tool wear prediction. Firstly, the fusion of physical and data information is achieved through cross-physical data modeling. Second, a multi-channel 1D-CNN convolutional neural network is utilized to reduce the complexity of local feature extraction. In addition, a loss function considering physical subject factors is proposed to quantify the physical inconsistency. Experiments of the proposed model are carried out on carbon fiber reinforced ceramic matrix composites to validate the performance of the model in terms of MAE and RMSE.
The objective of this study is to address the issue of data imbalance by augmenting the milling tool breakage dataset using Auxiliary Classifier Generative Adversarial Networks (ACGAN). The research team developed an ACGAN architecture capable of producing samples labeled with various states of tool breakage. To assess the fidelity of the ACGAN-generated data, this study employed evaluation metrics such as the Kullback-Leibler divergence, Euclidean distance, and the Pearson correlation coefficient, comparing the generated samples against actual samples. The findings indicate a high degree of similarity in data distribution between the synthetic and real samples, suggesting the effectiveness of the generated data for training purposes. This research introduces a cost-effective and efficient approach for data augmentation, significantly enhancing the capabilities of milling tool condition monitoring systems.
This study aims to achieve fast and accurate identification of tool breakage in multi-tooth milling cutters using methods such as thresholding, clustering, and neural networks. A multi-level thresholding strategy combining fixed thresholds and dynamic thresholds was designed to enable rapid and accurate response in tool breakage identification. The fuzzy c-means clustering algorithm (FCM) and one-dimensional convolutional Softmax classifier (1D-CNN Softmax) were employed to identify the tool breakage states, distinguishing between normal cutting, single-tooth breakage, and doubletooth breakage. Experimental results demonstrate that this method exhibits fast response and high accuracy in classifying the breakage states of the three-tooth milling cutter, achieving an accuracy rate of 98.6%. This research provides a rapid and accurate technique for tool breakage identification in the field of multi-tooth milling cutter tools.
The removal function in machining is not an ideal impulse function, and the material removal at any point on the workpiece is a superposition of the removal at that point from the distribution of removal at surrounding points. When the residence time suddenly jumped to zero at the edge, the removal function and the residence time convolution results will gradually decrease at the edge, the removal matrix at the edge of the formation of the "collapse", after many convolution iterations, the edge of the face shape of the error convergence rate is lower than the other positions, resulting in edge effects. This paper firstly put forward an iterative algorithm based on the residence time of the cylindrical projection, and then analyze the edge effect in the iterative algorithm, and put forward two methods to suppress the edge effect, and select different removal functions and the form error on the algorithm to carry on the simulation calculation. Finally, the results of machining of mold #54 verifies the effective suppression of edge effect error by the method in this paper.
In this paper, a white light interference detection device is mainly established to measure the surface roughness of the focusing lens mold to test whether the surface roughness of the mold meets the requirements of making lenses. The model is established by SolidWorks software, the static and dynamic analysis of the machine tool model is carried out by Ansys Workbench software, and then the measurement experiment of the surface roughness of the focusing mirror mold is carried out.
EP satellite is a scientific exploration satellite for time-domain astronomy and high-energy astrophysics, its function is to carry out high-energy transitory celestial body survey with the highest sensitivity in the soft x-ray band. EP will be equipped with two groups of x-rays focusing mirrors (each group contains 54 Wolter-I mirrors). An x-ray focusing mirror is used to collect x-ray radiation in the universe, and is the core component of an x-ray astronomical satellite observation payload. The current x-ray focusing mirrors are derived from the Wolter-I reflector, and the light is focused through the inner surface. The inner reflection surface is an optical free-form surface connected by parabolic and hyperbolic surfaces. Many conventional measurement methods are not applicable and difficult to measure. High precision contact measurement is easy to scratch the mirror surface, Therefore, non-contact measurement must be used. In this paper, we develop two non-contact surface precision measurement devices are developed to solve the problem of difficult measurement of the inner reflection surface of the x-ray focusing mirror. One is a rapid measurement device based on the principle of optical star measurement method, The other is to measure the mirror inner surface by a single point scan measurement, the optical triangulation method is selected as the principle of the measurement device. We then verified the measurement accuracy of the mirrors with a precision visible light test system. In order to further verify the measurement accuracy of the focusing mirrors, x-ray testing of the focusing mirror was carried out at the 100-meter vacuum x-ray calibration facility of the Institute of High Energy Physics, Chinese Academy of Sciences. The x-ray measurement results are better than the project index requirements.
Temporary sources and explosive celestial bodies in the universe can only be observed through their high-energy radiation, for example X-rays. The multilayer nested Wolter-I type focusing mirror is widely used in X-ray astronomical telescopes. The electroforming replication process can achieve batch high-precision production of Wolter-I type focusing mirrors, with the process flow of mold ultra-precision turning, ultra-smooth, coating, electroforming, and demolding. The fabrication of molds accounts for a large proportion in the process, and the molds accuracy and surface quality directly determine the optical performance of the mirrors. We built the DRL2000 ultra-precision lathe for mold turning of mission EP (Einstein Probe) and eXTP (enhanced X-ray Timing and Polarimetry mission). The swing straightness error of the guide rail was separated and compensated through trial cutting and reverse measurement methods to achieve a turning generatrix accuracy of peak-to-valley (PV)<0.2μm. An in-situ measurement device has been built based on the ultra-precision lathe. After adjustment the system measurement error can be controlled within 0.1μm. The corresponding spiral measurement path and coaxiality error separation method were studied and verified through experiments. An offline measurement device was built and based on it, an optical lever measurement method was preliminarily validated. Finally, a division method of medium-low frequency error and medium-high frequency error was proposed.
EP satellite is a scientific exploration satellite for time-domain astronomy and high-energy astrophysics, its function is to carry out high-energy transitory celestial body survey with the highest sensitivity in the soft X-ray band. EP will be equipped with two groups of x-rays focusing mirrors (each group contains 54 Wolter-I mirrors). An X-ray focusing mirror is used to collect X-ray radiation in the universe, and is the core component of an X-ray astronomical satellite observation payload. The current X-ray focusing mirrors are derived from the Wolter-I reflector, and the light is focused through the inner surface. The inner reflection surface is an optical free-form surface connected by parabolic and hyperbolic surfaces. Many conventional measurement methods are not applicable and difficult to measure. High precision contact measurement is easy to scratch the mirror surface, Therefore, noncontact measurement must be used. In this paper, we develop two non-contact surface precision measurement devices are developed to solve the problem of difficult measurement of the inner reflection surface of the X-ray focusing mirror. One is a rapid measurement device based on the principle of optical star measurement method, The other is to measure the mirror inner surface by a single point scan measurement, the optical triangulation method is selected as the principle of the measurement device. We then verified the measurement accuracy of the mirrors with a precision visible light test system. In order to further verify the measurement accuracy of the focusing mirrors, X-ray testing of the focusing mirror was carried out at the 100-meter vacuum X-ray calibration facility of the Institute of High Energy Physics, Chinese Academy of Sciences. The X-ray measurement results are better than the project index requirements.
For most of the current white light interferometer mechanical structure are vertical structure and the size of the inspected parts have limitations, this paper mainly uses white light vertical scanning measurement technology to develop the measurement system for in-situ measurement of ultra-precision machined parts surface three-dimensional topography, white light interferometer mechanical structure design and machine tool integration, to carry out the design of the mechanical structure of the white light interferometer and the integration of the machine tool, and the completion of the measurement system to build a physical example of the system to test the verification of the reliability of the system.
Based on chemical-mechanical polishing and combining mechanical and tribochemical polishing techniques, a precision lapping method suitable for parabolic polishing specified by grazing incident X-rays is introduced. Various factors affecting the polishing process are analyzed, and the results show that the proposed method is consistent with Preston's equation and Hertz contact principle. Therefore, this paper proposes a general material removal model based on the above two methods. The mid and high-spatial frequency errors are demanded to reach the requirements with an angular resolution consistently < 6 arcsec HEW and a roughness of 0.3 nm rms (between 1 mm and 0.002 mm spatial frequency range). To achieve the conformal ultra-smooth polishing of focusing mirrors, the process of full-aperture super-smooth pitch polishing is investigated. The influences of key polishing parameters are revealed. The evolution of the surface topology has been studied. A polishing setup is established to carry out experimental polishing to verify the optimum processing parameters obtained by simulations and previous polishing tests. Besides, the effect of abrasive particle size on the roughness is also verified. The roughness of the polished mandrel is measured at different positions, and the optimum roughness reaches Ra 0.359 nm. The polishing approach can significantly reduce the surface roughness of the replication mandrel, satisfying the low energy band focusing requirement of grazing incidence X-ray mirrors.
In order to solve the problems of complexity and inefficiency in traditional processing modes of aspherical optical components, the paper designs a compound machine tool based on the gantry structure and capable of double-sided machining. The tool spindles on both sides can be modularly replaced according to the selected combination process, thus guarantee a certain degree of flexibility in processing. Firstly, the structure of the machine tool is designed and 3D modeled. After that, the stiffness models of the classical joints are analyzed, and the finite element analysis of the whole machine is carried out based on the virtual structure method. On the basis of structural design and simulation analysis, the mathematical model of the beam optimization problem is established, and the lightweight design of the beam is carried out by using the adaptive multi-objective method. The simulation results show that the design and analysis of the multi-axis optical compound machining machine tool is reasonable and effective.
In order to achieve replication of the ultra-thin metal x-ray focusing mirrors with high accuracy and efficiency, which is the key component of the EP satellite independently developed and manufactured in China, the simulation and experimental research on the demolding process of the x-ray focusing mirrors are carried out in this paper. The temperature and stress fields of the entire mandrel (aluminum) and the shell (nickel) during cooling process is simulated by finite element analysis, and the evolution of the interface stress during the demolding process is analyzed. When the temperature of the mandrel and shell decreases from 45℃ to 10℃, the equivalent stress at the interface between the mandrel and the mirror reaches 5.5MPa, which is larger than the adhesion strength between Au film and mandrel. Due to the difference in material thermal expansion coefficient between the mandrel and the mirror, it can be used to release the x-ray focusing mirror shell from the mandrel by cooling according to the experimental validation. Furthermore, the shell could separate from the mandrel by means of high precision demolding automatic device. After demolding, the angular resolution of the mirror is 25.1 "HPD (Half Power Diameter) by the x-ray testing, which meets the requirements of the project. The reliability and advancement of the technology are verified.
With the vertical fluctuation of small amplitudes, the quasi-planar freeform surface is essentially a plane superposed by microstructure with several micrometers. In practical, it’s widely used to improve the optical performance. However, its form accuracy highly depends on the processing iteration with all kinds of computer controlled optical surfacing (CCOS) technology. This paper presents an automatic characterization method for the quasi-planar freeform surface by atmospheric pressure plasma processing (APPP). Firstly, the principle of APPP and fabrication of the typical quasi-planar freeform surface are introduced. Based on this, an automatic characterization method is developed to eliminate the misalignment between the measured and designed surface, which serves for the form error evaluation and removal generation of next processing step. Finally, the simulation and experiment were conducted to demonstrate the effectiveness of the proposed method, which indicates that it can provide the reliable feedback for the fabrication of quasi-planar freeform surface.
Over the past few years, atmospheric Inductively Coupled Plasma (ICP) has aroused extensive attention in optical fabrication field since its chemical etching-based processing mode does not mechanically damage work-pieces. However, the principle of chemical etching will inevitably bring some processing temperature while maintaining the efficiency. This makes the ICP jet easily cause thermal damage to the ultra-thin or low thermal conductivity optical elements, even cause the element to crack seriously. Therefore, this paper proposes a velocity-region dual adaptive path planning algorithm, which reduces the processing temperature by limiting the moving velocity of a single path, and achieves the removal of excessive peaks through Repeated traversals.
The Einstein Probe (EP) is an X-ray astronomical mission mainly devoting to time-domain astronomy. There are two main scientific payloads onboard EP, the Wide Field X-ray Telescope (WXT) based on the lobster eye optics and the Follow-up X-ray Telescope (FXT). FXT contains two Wolter-1 mirrors with a pnCCD detector on each focus. The total effective area is about 600 cm2 and the energy range is 0.3-10 keV. The pnCCD detector cooled by a pulse tube cooler enables high-resolution spectroscopy and imaging combined with excellent time resolution. It will also have several working modes with time resolution ranging from tens of microseconds to 50 milliseconds. Currently, the FXT is in its qualification model phase. The mirror assemblies (STM and TCM) as well as the pnCCD EM module have been manufactured and tested.
This paper presents a novel desktop device for lapping thin-walled micro groove of a specimen used in optical equipment,
the device is aimed to remove metamorphic layer (about 1μm thick) formed on the groove’s upper surface as well as
ensure its thickness accuracy. It adopts the way of macro/micro motion combination, the macro-motion table uses stepper
motor and ball screws to realize motion in large stroke, high speed and the micron level positioning, the micro-motion
table uses the electrostriction appliance to actuate the flexible four bars mechanism to realize the small stroke, low speed,
and the submicron level positioning. The system uses the strategy of two ways of feedback, the macro/micro motion
table uses the precise linear grating as close-loop position feedback, and the sensing holder uses the eddy current
transducer as the force and deformation feedback of the elastic fixture. The most novel aspect is the first proposed idea of
realizing automatic feeding by elastic recovery of the fixture, whose structure has been delicately designed. In order to
ensure small lapping force and relatively high natural frequency, both static and modal analysis of the fixture has been
done by ANSYS, the results was in good accordance with experiments. Lapping experiments have showed that this
device can remove metamorphic layer efficiently as well as obtain good surface quality at the same time.
Atmospheric Pressure Plasma Processing (APPP) using inductively coupled plasma has demonstrated that it can achieve comparable removal rate on the optical surface of fused silica under the atmosphere pressure and has the advantage of inducing no sub-surface damage for its non-contact and chemical etching mechanism. APPP technology is a cost effective way, compared with traditional mechanical polishing, magnetorheological finishing and ion beam figuring. Thus, due to these advantages, this technology is being tested to fabricate large aperture optics of fused silica to help shorten the polishing time in optics fabrication chain. Now our group proposes to use inductively coupled plasma processing technology to fabricate ground surface of fused silica directly after the grinding stage. In this paper, form control method and several processing parameters are investigated to evaluate the removal efficiency and the surface quality, including the robustness of removal function, velocity control mode and tool path strategy. However, because of the high heat flux of inductively coupled plasma, the removal depth with time can be non-linear and the ground surface evolvement will be affected. The heat polishing phenomenon is founded. The value of surface roughness is reduced greatly, which is very helpful to reduce the time of follow-up mechanical polishing. Finally, conformal and deterministic polishing experiments are analyzed and discussed. The form error is less 3%, before and after the APPP, when 10μm depth of uniform removal is achieved on a 60×60mm ground fused silica. Also, a basin feature is fabricated to demonstrate the figuring capability and stability. Thus, APPP is a promising technology in processing the large aperture optics.
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