Milling thin walled structures is challenging due to their low stiffness and hence consequential vibration problems. So some measures need to be taken to suppress chatter. Based on the vibration absorption principle of tuned mass damper (TMD), the vibration suppression auxiliary fixture is designed according to the finite element analysis and modal experiment results. The proposed auxiliary fixture does not require additional power unit, with simple structure, easy installation,flexible and convenient advantages and can be widely used in industrial manufacturing. The experimental results show that the amplitude of the low frequency vibration of the system reduced by 90%, the amplitude of the high frequency vibration reduced by 70%, and the coupling vibration amplitude of the tool and the workpiece reduced by 80%.

It is difficult to make accurate prediction the development trend of machine tool industry, because there are too many reasons that will affect it. However, in the commodity society, individuals and enterprises generally pursue maximization of economic benefits as the basic principle. The highest benefit that machine tool was used to process will reflects the capability. The unit time capital profit rate used to evaluate the quality of process parameters has been proposed. In this paper, a machine tool evaluation method based on the capital profit rate per unit time is proposed, based on this, several possible development directions of machine tool prediction are proposed, in hopes of providing an effective ideas for future machine tool research and development to enhance the performance of ways.

T type joints, which often affect the quality of the whole structural parts, are widely used in the stiffened wall plate of large components. In view of the above problems, a dual-beam laser welding platform is built to meet the welding requirements of large size structural parts. Then, the ten-axis six-linkage CNC system is designed to meet the needs of both sides welding of T type joint at the same time. While controlling the position and attitude of the 3D welding, the welding seam measurement and tracking compensation on both sides of the T type joint are realized simultaneously. Through the actual welding experiment, the control system of dual-beam laser welding and seam tracking with ten-axis sixlinkage is tested and the result shows it can meet the processing requirements for T type joints.

With the development of CNC machine tools toward high-precision, high-speed and greening, the advantages of lightweight CNC machines become more and more obvious. Taking ZN-XK2840 CNC gantry boring and milling machine as an example, this paper presents a lightweight design method of CNC machine tools based on particle damping technology. Firstly, the static property of the conventional CNC machine tool structure is analyzed by finite element method, the wall thickness is optimized, and the static property of the lightweight machine tool structure is analyzed to ensure that the maximum deformation and strength meet the requirements. Then analyze the dynamic property of conventional CNC machine tools such as modal characteristics, harmonic response. The particle damping technology can effectively reduce the vibration of the machine tool structure in the vibration transfer path. In this paper, through the establishment of particle system-gantry milling machine dynamics model, using discrete elemental dynamics software developed by ourselves to analyze the dynamic property of the machine tool with particle damper installed. By comparing with the dynamic property of conventional machine tools, it is found that the dynamic property of lightweight machine tool is better than conventional machine tools. According to the lightweight design, the gantry boring and milling machine with particle damper is installed. The acceleration amplitude and displacement amplitude are measured during the idling and milling process, which are all smaller than the conventional machine tools. Its weight is 53.8% lower than similar products, effectively reducing the weight.

Real-time recognition of cutting tool states plays an important role to improve the efficiency and quality and reduce the cost of CNC machining. For complex parts with single-piece or small batch production, the geometry and cutting parameters in the machining process are constantly changing which makes a great challenge for accurate recognition of cutting tool state. To address the above problems, this paper presents a cutting tool state recognition approach based on cutting force signals, geometric information and process information. The cutting force signals of different tool states are collected and analyzed. The time analysis and time-frequency analysis methods are used to extract the features of cutting force signals. Associated with the machining process information and the geometric information of the parts, the input vector is established. Cutting tool state recognition model based on neural network is established and trained. The real-time recognition of cutting tool state is realized with the neural network model during the actual machining process. Experiments show that the approach can solve the real-time recognition of cutting tool states.

Intelligent CNC machine tool is production terminal equipment of smart factory in the era of Industries 4.0. Technical implementation of network, intelligence and collaborative manufacturing of this machine tool can not do without open smart CNC which has high stability and precision retaining ability. In this paper, aimed at real-time optimization of cutting parameters during milling process, functional software modular is designed and developed in the platform of open modular architecture CNC. The algorithm of intelligent control is integrated into system coordinator modular of CNC, which could adjust spindle speed and feed rate in real-time through processing cutting force signals. The effectiveness of proposed smart CNC is validated by thin-wall cutting experiments.

To satisfy the requirements for manufacturing complex surfaces and narrow deep cavity parts in aviation, medical, automobile and other industries, a CNC electrochemical milling system is developed, including: design of a machine tool with four-axis linkage (axis X/Y/Z and rotating axis C) at a repositioning accuracy of 2μm; development of a pulse power supply with high frequency, fast short circuit response and communication with the control system in realtime; an electrolyte circulating filtration system with 0.5μm filter precision, controllable pressure and temperature. Finally, a tubular electrode was employed for electrochemical milling high depth to width ratio structure on 304 stainless steel surface with this system. A narrow slot with the width of 1.4mm, depth of 8mm, and surface roughness of Ra0.8μm was successfully manufactured. The machining process was stable and the side wall of the slot was steep. It indicated that the developed system has reached the desired design goal.

In order to improve the accuracy of large-size aircraft ribs assembly location, reduce the deformation of the assembly and finally meet the requirements of the deviation of the ribs spacing in the wing box assembly process, based on the analysis of the assembly positioning requirements and the position uncertainty of the large-size ribs assembly, a kind of rigid assembling technology of dot matrix was proposed. A new set of rigid lattice enhancing tool was designed based on the deformation analysis, which realized the large-size rib-shaped positioning and the multi-degree-of-freedom adjustment of the positioner. It reduces the deformation of the ribs and ensures the ribs spacing, which is of guiding value for the actual assembly of the large-size aircraft ribs.

The microstructure and microhardness of Ti-6Al-4V α-case which experiences thermal exposure at 900℃ , 930℃ and 960℃ are investigated. After thermal exposure of 0.5-24h, the volume fraction of α is much higher in α-case than in sample interior, and the grains grow larger comparing with the original material. The α-case thickness increases with time and temperature increasing. Due to the strengthening effect of oxygen, the microhardness of α-case thickness also increases. The microhardness value decreases from the surface to the interior of the sample, and it becomes stable below 200μm. The α-case on the fatigue sample induces a multi-site fatigue crack initiation mode, which leads to a significant deterioration of fatigue life.

Silicon carbide matrix composites are composed of fibers, matrices and their interphases. The interphase,which connects the fiber and the matrix, has a significant impact on the performance of the composites. The most commonly used interphases are pyrolytic carbon and boron nitride. The preparation technology of pyrolytic carbon is relatively mature, but its long term use under high temperature oxidizing atmosphere is limited since it is prone to get oxidation when the temperature is above 400℃. The preparation technology of boron nitride has developed very rapidly in recent years and various new kinds of raw materials and preparation techniques have emerged. In terms of evaluation methods of the interphase,although it is very important to optimize the performance of the composites, the major problems are the difficulty in sample preparation and data dispersity. In this paper, the role of the interphase in silicon carbide matrix composites, common kinds of the interphases and their preparation technologies, the evaluation methods, and the future development trends of the interphases have been discussed comprehensively. There is a great space for further research on the development of new precursors, the development of new preparation techniques and the improvement of the utilization rate of raw materials. The further development of material properties and the design of multi-layer interfacial layer are the future trends. This paper has certain reference value for the development in the field.

Based on the analysis of the composite material and its advanced manufacturing technology, with the process of fiber placement, an analysis technology of composite material fiber placement based on triangular mesh was proposed. The paper summarizes the current approach and the equidistant path planning method integrating the analysis mechanism, and we analyzed the targets of turning radius and angular deviation on the center lines. Through the result of analysis, we established the partition mechanism. With the mechanism, the original surface area of the ply was divided into some sectors independent to fiber geometry generation to improve the quality of the composite product. The CATIA secondary development tool CAA was used to realize the function of generation and analysis of the fiber geometry on the Microsoft Visual Studio 2005 platform, and the correctness of the analysis result and the partition result was validated. This research provides an important idea for the development of advanced manufacturing technology of composite materials.

Ultrasonic-assisted drilling (UAD) is employed to solve the problems of large drilling stress, difficulty of chip breaking and removal, and poor machining quality in micro drilling of stainless steel. Drill trajectory and axial cutting thickness in conventional drilling (CD) and UAD processes were analyzed. The effect of ultrasonic vibration on drilling force, chip curling radius and hole morphology were investigated based on the finite element simulation and experiment results. The results indicate that compared with CD, the effective cutting time and cutting stress under chisel edge are reduced significantly, the chip curling radius is smaller and thus chip is easier to break, the thrust force and entrance burr are reduced, and micro-hole quality is improved in the UAD process.