Compared with off-line measurement, on-machine measurement technology has the advantages of low cost, measurement during processing, no handling and repeated clamping. It provides a new technical means for precision manufacturing of complex curved parts such as aviation turbine blade, aircraft fuselage wing skin, nuclear turbine large blade, automobile engine crankshaft and so on. However, there are still two technical difficulties in the actual operation process: (1) The accuracy of the contact type on-machine measurement is high. However, due to the limitation of single point contact acquisition mode, the measurement efficiency can not meet the demand of full-scale mass measurement of industrial parts. It is only suitable for precise measurement of key dimension characteristics of parts or in-depth measurement of complex structures with serious interference. (2) The position and pose calibration accuracy of non-contact sensor directly affects the measurement accuracy, which is also affected by projection direction and measurement depth of field. How to take the above factors into consideration for accurate calibration of sensor pose and automatic planning of mea urement path is an urgent problem to be solved. For these problems, this paper systematically introduces the contact/non-contact on-machine measurement system architecture, contact on-machine measuring path planning, non-contact on-machine measurement parameter calibration and path planning theories. Based on this, iPoint3D OnsitesSan, a special software for non-contact on-machine measurement data collection and processing is developed, and the applications of the software in the measurement of aero-engine impeller, aerospace frame beam wall, aircraft skin, flange sealing surface of nuclear main pump is introduced. The development trend of on-machine measurement technology is discussed in the final.

Carbon fiber reinforced polymers (CFRP) are used in the field of aerospace due to their superior properties. At present, the researches on CFRP cutting mainly focus on single milling, but the multiple milling strategies are widely used in actual machining, the influence of multiple milling on subsurface damage cannot be ignored. In order to make up for this gap, VUMAT subroutine is used to establish three-dimensional Hashin failure criterion and CFRP multiple milling finite element model. The accuracy of the simulation model is verified by experiments. The model is used to analyze the variation of cutting force and surface damage with fiber direction angle (0°, 45°, 90°, 135°). The results show that the cutting force of the second milling is less than the first milling in the multiple milling strategies, and the cutting force follows the rule of 90°>135°>45°>0°. The subsurface damage is lower than that of single milling, and the damage factor increases with the increase of fiber direction angle. When the fiber direction angle is 0, the damage factor is the smallest, and the fiber direction angle is 135°, the damage factor is the largest, the subsurface damage is the most serious.

When an industrial robot is operational continuously in industrial field, the position of the end effector would drift. Using external high-precision measurement system to get the accurate 3D position coordinate of the end effector is an effective method of compensating the absolute positioning error of the robot. The measurements required efficient, high-precision and adaptability, to deal with these problems, in this paper, an error compensation method of industrial robot based on workspace measurement and positioning system is proposed. Based on the dynamic performance of the system, a meshing strategy for robot workspace is designed. The grid edge length could be adjusted according to the actual distribution of positioning errors. After collecting the absolute positioning error vector values of grid nodes, for the interpolation calculation of the position error vector at key trajectory nodes, the inverse distance weighting algorithm is studied to realize the compensation of the position errors of the end effector. The experimental results exhibit that after installing 20kg load, the average absolute positioning error of the robot is reduced from 1.36mm to 0.19mm, the absolute positioning accuracy of the robot is improved by about 86% after compensation. It indicates that this proposed high-efficient method can significantly improve the site operation accuracy of the industrial robot.

The laser multi-degree-of-freedom (MDOF) error measurement methods are widely used for measuring motion errors of machine tools. Since a laser diode has the advantage of small size and low cost, it is always adopted as the laser source of the laser MDOF error measurement system. However, the stability of the laser MDOF error measurement system will be influenced by the laser beam drifts, which are caused by the atmospheric distribution and the deformation of the optical elements and its holders. In addition, the beam spot of the laser diode is elliptical, which will influence the accuracy of the laser MDOF error measurement system. Therefore, a laser beam drifts compensation method is proposed to reduce the effects of the laser beam drifts on the measurement accuracy of the system. In the meantime, a beam shaping method is proposed to shape the laser diode spot. A laser diode-based MDOF error measurement system is conducted according to the measurement principle, the compensation principle and the beam shaping principle. It is verified that the stabilities of the horizontal and vertical straightness signals and the pitch and yaw angular signals are improved to be 5.5μm, 2.5μm, 1.3arcsec and 1.7arcsec with the laser beam drifts compensation from 6.9μm, 6.7μm, 5.4arcsec and 4.6arcsec without the laser beam drifts compensation. The measurement accuracy of the designed measurement system for measuring the straightness errors and the angular errors are better than 1.9μm and 1.6arcsec.

According to the measurement technology requirements of aircraft assembly for large-volume, high precision, strong compatibility, good expansibility and fast networking, the research on establishment technology of large-volume multi-system measurement field for aircraft assembly is carried out, the principle of measuring reference optimization design is proposed and the multi station redundant measurement length constraint algorithm is adopted based on laser tracker. A 3D precision reference measurement field compatible with aircraft assembly equipment is constructed, and the calibration accuracy of the reference field is verified by experimental comparison. Eventually, through a typical application case, this paper expounds the construction technology of large-volume multi-system measurement filed in the process of aircraft assembly, which promotes the improvement of aircraft assembly measurement technology.

For the shortage of the current study on measurement uncertainty evaluation of turbine nozzle throat area measured by coordinate measurement machine (CMM), a measurement uncertainty evaluation model of turbine nozzle throat area measured by CMM was proposed by analyzing measurement procedure and principle. Finally, measurement uncertainties of single throat area and area of all throat in circle were evaluated according to a measurement case. The evaluation result shows the CMM method could meet the design requirement of turbine nozzle throat area.

In recent years, rapid development of aerospace and aeronautic industries demands for light-weight, high strength, and fatigue resistant aluminum alloys. Predictions of cast defects and technologies of controlling those defects become more and more important. Hydrogen porosity is one of the major initiators for the fatigue failures of aluminum alloys, which forms during solidification. In the foreign companies, mathematical models such as cellular automaton (CA) model have been widely used to optimize the advanced casting practices such as single crystal turbine blades, turbine disc, and exterior frames for aircraft engines. This paper summarizes the most recent progresses of defect prediction models for solidification process, and propose the future directions for modeling of casting defects.

In arder to improve the overlap quality of multi-beam selective laser melting, the effects of scan order of overlap area on surface appearance, metallurgical defects, tensile properties and other formability of TC4 samples have been investigated. The results show that, when the strips between adjacent layers have no relative deflection, due to the denudation of the powder, reverse order overlap causes large surface fluctuation at the overlap area using dual lasers, and is easy to cause defects of poor fusion; In order overlap can greatly eliminate surface fluctuations in the overlap area and reduce internal defects; When setting the relative strip deflection angle between adjacent layers of 67°, in order overlap can avoid internal defects and improve the surface morphology of the overlap area, and the microhardness and tensile strength are basically the same as when using reverse order. The in order overlap and the relative strip deflection between adjacent layers can improve the forming quality of the overlap area when using selective multi-beam laser melting technique.

Aiming at the technical problems that the numerical control (NC) programming quality of the casing parts for aero-engine is difficult to control effectively, and the efficiency and flexibility of NC programming are poor, this paper proposes an automatic programming solution for the typical casing parts for aero-engine. In order to improve the efficiency and quality of NC programming of the casing parts, the automatic programmed of NC machining programming is realized by customizing the automatic programming tool under the environment of UG CAM.