A thermal error control method based on active cooling is proposed for precision machine tools.By designing a cooling scheme for the precision machine tool spindle system,a precision machine tool spindle cooling system based on active cooling was built,and a thermal fluid solid coupling simulation model of PT-400H CNC machine tool was established.The thermal error simulation experiment of the machine tool was conducted.The experimental results show that under the constant temperature cooling of 20℃,the time for the spindle to reach thermal equilibrium is effectively shortened,and the maximum thermal elongation is reduced by 15μm.The simulation results prove the effectiveness of the proposed active cooling scheme and provide a basis for further experimental verification.
The experimental procedure of inertial actuators was explored in the thermal vacuum environment within the aircraft attitude control system.An overview of the functionalities of inertial actuators and the principles behind thermal vacuum testing were provided.It outlines the experimental procedure,encompassing specimen and equipment preparation,establishment of the test environment,execution of the experiments,and data processing.The key technical aspects of the experiments were discussed,including environmental control,data handling and result analysis.The case studies presented to showcase the practical effectiveness and value of thermal vacuum testing.The research results could improve the per-formance and reliability of inertial actuators in the aircraft attitude control system under extreme environmental conditions.
As the important bearing parts of the aircraft,the monolithic panel and hollow beam structures are developing towards the direction of integration,light weight and high integration.The shot peening technology,as a new and efficient forming strengthening technology,has been widely used in the forming process of aircraft structural parts.There are many technical problems to be solved,such as partial instability of shot-peening forming and uneven surface caused by the re-bound deformation of pits,which seriously affect the product quality.The research status of shot peening was reviewed,and the key technical problems were analyzed,which provided a new idea for further research on shot peening technology of large aircraft structural parts.
According to the technical requirements of the positioning trolley used for measuring the electrical thickness of the radar cover,design and strength analysis are conducted on the mechanical system of a certain positioning trolley.The results indicate that the mechanical system function of the positioning trolley meets the usage needs,and the structural strength meets the material performance,laying the foundation for subsequent mechanical design.
Using sensors to collect spacecraft flight parameters,a distributed communication network with multiple sensors for spacecraft was constructed,and global rewards to determine the optimal communication channel was used.By using the transform domain optimization method to achieve anti-interference processing in the frequency domain of the channel,Stackelberg's power domain anti-interference method was used when the interference was severe to determine the optimal transmission power and complete the joint anti-interference of spacecraft in multiple domains.The experimental results indicated that this method can make anti-interference decisions for different types of interference,maintaining the spacecraft communication network in a stable communication state.
In order to solve the problems of poor repeatability,inaccurate control of sample strain rate and small strain rate span of air gun loading in traditional Hopkinson pressure bar experiment,a reliable control system composed of con-trol cabinet and main circuit power cabinet was designed based on the principle of electromagnetic compatibility,and the hardware circuit design of the control system was completed.In terms of software,based on the working process and func-tional requirements of electromagnetic loading equipment,PLC terminal address allocation,various subroutines design and touch screen human-machine interface configuration were completed.The experiments showed that the system had stable performance and a foundation for the next step of development was provided.
The shortcomings of general-purpose computers for vision development and the advantages of embedded plat-forms were expounded.The embedded vision development platform widely used at present was introduced.The problems of using domestic hardware for embedded development were pointed out.The construction of embedded vision development platform based on T3 evaluation board was completed.During the process of platform construction,the problems such as the support of the evaluation board for UVC cameras,the replacement of the Linux embedded system file system,and the expansion of the file system partition of the Micro SD boot card were solved,laying a foundation for subsequent embedded vision development.
Aiming at the problem that it is difficult to accurately measure the diameter of the riveted rivet and its corre-sponding position at the same time in the research on the interference of automatic drilling and riveting,the measurement method based on optical scanning was used to complete experimental on the interference of automatic drilling and riveting.The experimental piece was composed of two aluminum-lithium alloy plates,the thickness of the single plate was 2.4mm,and the countersunk rivets were used.The experimental results show that the method based on optical scanning can notonly accurately measure the diameter and position of the rivet,but also obtain the overall distribution of the diameter of the rivet.The distribution of the interference of automatic drilling riveting is not uniform,and the maximum interference appears on the side of the driven head,the minimum value of interference appears on the rivet head.The distribution law is strictly descending from the driven head to the rivet head.The coefficient of variation of the automatic drilling and riveting inter-ference obtained by precise measurement is 0.201.
Aiming at the difficulties in profile error calculation of blades,the registration process of blade profile lines was divided into coarse registration and fine registration.The former was achieved through the transformation matrix H1,which is a rigid transformation between measured data and theoretical data.The latter was achieved by transforming the matrix H2,using the sum of squared distances as the objective function,and using the random gradient descent method to calculate the rotation angle and displacement in H2.After completing the registration of the blade profile,the distance between the measured data points and the two nearest theoretical data points on the straight line was applied to calculate the blade profile error and perform symbol judgment.10 sets of blade profile data points were selected for comparative analysis in the experiment.The deviation of the evaluation results for the profile error of each group of blades was smaller than±7μm.The effectiveness and accuracy level of the methods have been verified.
According to the structural characteristics and welding technology requirements,carried out vacuum brazing tests on 6063 aluminum alloy antenna horn structure,to determine the amount of brazing material,tooling pre-pressure stress,welding process parameters,to meet the product on the cavity of the brazing material diffusion,brazing angle size,brazing rate and the amount of deformation control requirements,the weld quality by the appearance of the inspection,metallurgical inspection and ultrasonic C scanning test,was confirmed.
Based on the current production status,the bottleneck of intelligent manufacturing of aviation wiring har-nesses is analyzed,and combined with the advanced technology and equipment in the wiring harness industry,the analysis and research of automation transformation direction is carried out from three aspects:iterative upgrading of production equipment,optimization and improvement of process flow,and digital management of production process,so as to provide solutions for intelligent manufacturing of aviation wiring harnesses.
Numerical simulations for sealing characteristics of labyrinth in compressor stator well were carried out.The effects of rotational speed,pressure ratio and inlet swirl ratio on the sealing characteristics of labyrinth with rotating disc cavities were analyzed according to the comparison with that of labyrinth without rotating disc cavities.Rotating disc cavities change the inlet and outlet boundary conditions of labyrinth,and have obvious influence on the sealing character-istics.Compared with labyrinth without rotating disc cavities,labyrinth with rotating disc cavities has the better sealing capability and higher outlet swirl ratio.With the increasing of the rotational speed,the discharge coefficient declines,and the outlet swirl ratio increase.With the increasing of pressure ratio,the discharge coefficient increase,while the outlet swirl ratio decreases.At high pressure ratio,the variations change slightly.With the increasing of inlet swirl ratio,the discharge coefficient decreases,while the outlet swirl ratio increases.
In this paper,a test method for the distribution characteristics of nitrogen enriched air in aircraft inerting system was studied.Based on the ground nitrogen enriched air simulation system,the three parameters such as nitrogen enriched air flow,fuel tank load condition and nitrogen enriched air oxygen concentration were taken as independent variables.Simulated distribution carried out in the 1:1 simulated aircraft fuel tank.This method can assist to verify the distribution performance of nitrogen enriched air of inerting system.
《航空精密制造技术》(双月刊)创刊于 1963 年,是由中国航空工业集团有限公司主管、北京航空精密机械研究所主办的、国内外公开发行的技术性刊物(CN11-2847/V ISSN 1003-5451 ).
Taking a commonly used double-sided buckle type rubber shock absorber as the research object,the stiffness calculation model of the shock absorber is established by analyzing the force on the rubber shock absorber,and the rela-tionship between the stiffness of the shock absorber and the stiffness of a single rubber block is given.The simulation and experimental methods were used to study the stiffness characteristics of single piece rubber blocks and shock absorbers.The research has shown that under small deformation conditions,the compression and shear stiffness of the buckle type rubber shock absorber are twice that of a single rubber block.The accuracy of the shock absorber's mechanical model has been verified through simulation analysis and experimental testing;The study can provide a method reference for the design and analysis of double-sided buckle type rubber shock absorbers.
When turning single crystal germanium end faces with single point diamond,the surface may exhibit a phe-nomenon of alternating light and dark sector domains,which is closely related to processing parameters.By analyzing the influence of material properties on the critical undeformed chip thickness of brittle plastic transition,the possible reasons for the appearance of the bright and dark sector phenomenon are pointed out.By combining orthogonal experiments,the effects of spindle speed,cutting depth,and feed rate on the sector distribution of surface roughness in the bright and dark regions of single crystal germanium were studied.The range analysis of the experimental results was conducted to analyze the influence of various process parameters on the surface quality of the workpiece,providing reference.
Based on the analysis of the delay of a missile control system,a method for measuring the dynamic delay of the control system based on a three-axis turntable is proposed.The method is convenient and feasible,and can measure the dynamic delay time of the control system under various input conditions,which can be used to guide the design of the control system.The development costs could be saved.
Aiming at the main requirements of improving the detection and calibration of precision turntable control system,from the aspects of turntable control system design scheme,traditional PID controller research,BP neural network optimization PID controller research,PSO-BP combination algorithm optimization PID controller research technology,the main technical principle and simulation realization of improving the parameter index of turntable control system response under algorithm optimization were introduced.The mathematical model of turntable control system was established and simulated.The simulation results showed that the neural network PID controller optimized by PSO-BP combination algo-rithm achieved good control effect,strong robustness and high tracking accuracy,which provided a new idea for algorithm optimization of turntable control system.
During the ground commissioning,it was found that the oxygen consumption of the left engine ignition device of an aircraft was abnormal.The fault tree was drawn by analyzing the working principle of the engine oxygen supplement system,and the main reasons affecting the oxygen consumption of the engine ignition device were found by theoretical analysis combined with the ground test,and reasonable suggestions were given.It has strong theoretical significance and practical value for ensuring the normal oxygen consumption of engine ignition device.
Through the mechanical property test of aluminum-lithium alloy 8090,combined with the results of the me-chanical property test of materials,the finite element static simulation analysis of the three-inertia group aluminum-lithium alloy table body is carried out,and the optimization and iteration of the platform structure are carried out,and the prototype test results show that the application of aluminum-lithium alloy effectively improves the installation error of the three-inertia group table instrument in the locked state.
