Advanced Materials Research Vols. 591-593

Abstract: To improve quality and efficiency of NC machining sequencing, an approach to order the machining features of aircraft structural parts is introduced in accordance with the principle of hierarchical planning, knowledge and geometry-based reasoning method. The main contents consist of: (1) Machining cell and its geometric descriptions are established, and the method for decomposing generalized pocket (GP) into machining cells is proposed. (2) Based on the GP relationship tree, data model and algorithm for generating machining chain are presented. (3) Machining process segmenting, feature grouping and sequencing rules are formulated by communicating with related experts. (4) Priority graph and relationship matrix of features are applied to describe the machining precedence. The developed approach has been applied in Intelligent NC Programming System of Aircraft Structural Parts and is validated through a case study.

Abstract: Coaxial pulse tube cryocooler (PTC) acquires a perfect substitute for the existing Stirling cryocooler for providing reliable low-noise cooling for the given infrared detector system. The challenging work is the exacting requirement on its dimensions which have to adapt to the given Dewar.Warm end heat exchanger is the key assembly of the pulse tube cryocooler,and the coupling effect especially the heat exchange of the gas and solid in warm end heat exchanger directly affects the performance of the pulse tube cryocooler ,this paper briefly analyzes the differences of warm end heat exchangers in the form of cylinder gap,cylinder copper screen and taper gap.The status of every type of warm end heat exchanger are outlined, including the fabricating material and technique kernel , and especially introduce the taper gap warm end exchanger.In the end of the paper we conclude that the taper gap warm end exchanger can apparently improve the performance and minish the volume of the of the pulse tube cryocooler

Abstract: At present, CNC grinding efficiency has been low, the main reason is the grinding tool-grinding wheel. The service life of grinding wheel is an important element for restricting the grinding efficiency, and the main reason for affecting grinding wheel service life is the distribution of the grinding wheel grits. The chaotic distribution of grinding wheel grits reduces grinding efficiency. This paper analyzes the physical and chemical characteristics of the CBN grits, puts forward that through adding the magnetic field method in the process of electroplating wheel, changes the position and posture of CBN grits on the grinding wheel base body, and makes its an orderly distribution. And thus this method greatly improves the grinding efficiency and service life of the electroplating CBN grinding wheel.

Abstract: The present investigation was dedicated to elucidate grinding characteristics during surface grinding of titanium alloy(TC6) and high temperature alloy (GH2132) by using silicon carbide(SiC) and sol-gel (SG) wheel respectively. The grinding characteristic of SG wheel on aeronautical alloys was studied on the base of systematical measurement of the grinding force, grinding temperature, surface roughness and grinding ratio. The results indicated that the SG grinding wheel possesses excellent grinding properties and is more suitable for grinding these aeronautical alloys compared with conventional abrasive tools. Finally, the grinding mechanism of new-typed SG wheel was unveiled on the base of the microcrystalline structure analysis of SG grains.

Abstract: In order to solve the problem of tooth concave error appeared in the shaving course of non-modification disk-shaped shaving cutter, the worm type shaving cutter of open groove is studied. Firstly, the basic structure of the shaving cutter and the manufacturing process will be introduced in detail. The angle of front cutting edge is -30 ° or 30 °, and then the coincidence degree is approximately equal to 2, when the tool cut the gear in the direction of the oblique angle. Secondly, the tooth profile precision will be able to be achieved though circular grinding method based on both sides of the worm. Finally, the free shaving principle is discussed by analyzing the shaving movement, the drive speed and the cutting speed. According to the shaving gear experiment, the results show that the tooth precisions reach to the 6 grades.

Abstract: With the development of high technology war. Bionic autonomous underwater vehicle has become a popular issue these years, To Achieve better concealment, the stealth technology is the most difficult problem that must be solved. This paper briefly introduces the principle methods to keep the AUV quiet and difficult to be found, the advantages and disadvantages of all these extraction methods were analyzed. The stealth technology of underwater vehicle refers to the means that make the enemy’s sonar can’t detect their own location or shorten the distance, mainly including two aspects: noise control and acoustic antagonism. Finally, the development tendency of Bionic AUV stealth technology is provided.

Abstract: Application of turn-milling technology in aviation is investigated in this paper. First, consideration is given to the characteristics and machining tools of turn-milling technology. Second, the paper describes, in detail, the application of turn-milling technology in the aviation industry: Include crankshaft, integrated impeller and aviation system part. And then, the actual machining experiment of aircraft landing gear part is conducted by applying turn-milling technology. The experiment shows that surface roughness of the landing gear part is improved from Ra>1um to 0.3 um Ra and the machining efficiency is enhanced by 200% compared with conventional processing method. Finally, in accordance with the machining experiments, the prominent application advantages of the turn-milling in aviation are expounded. Besides, the application prospect of the turn-milling in the aviation industry is forecasted and six proposals are put forward.

Abstract: To improve the spray effects of fuel-jet nozzles, the deep micro-holes of the nozzles require taper angle 0°-2° along jet direction. In this paper, a taper-swinging mechanism (TSM) is designed to swing a taper angle on an electrode wire for micro electrical discharge machining (EDM) of micro-taper holes. The features of TSM are as follows. First, the electrode wire and its guider are swung simultaneously during the micro-EDM drilling. Second, the center of a fixed sphere as the taper vertex is positioned on the surface of workpiece. Thirdly, non-rotating of the electrode wire and the fixed center avoid the errors of the swing motion. The taper holes with the corresponding angles of 0.12°, 0.40°, 0.83°, and 1.32° were machined by using TSM. The batch production showed that the consistency accuracy of holes’ diameters reached 4μm. In addition, the TSM was applied in a micro EDM machine tool.

Abstract: Due to tool wear and making errors, calculating the tool path based on the tool theory model has a great deal of influence on the accuracy of surface finishing machining. In order to solve the above problem, a photogrammetry method is used to extract the rotary cutter profile, and then the tool surface is get by letting the fitting profile curve revolves about the cutter axis, finally the cutter contact path is obtained based on the minimal orientation-distance algorithm. Experiments prove the cutter contact path is just on the theory surface of the workpiece. Therefore the accuracy of surface finishing machining will be greatly improved by the method.

Abstract: The ‘Push’ of ERP (Enterprise Resource Planning) seems to be contradictory with the ‘Pull’ of Lean manufacturing; actually they have mutual promotion in production. The dual implementation of ERP and Lean is inevitable direction in the enterprise’s development. This paper first explains the difference and interrelation between ERP and Lean Manufacturing, and discusses the mutual promoted effects. Then focus on “how to accomplish the dual implementation” To answer this question, this paper mainly put forward three points: firstly strength the centralized management of all kinds of data and information in manufacture; then fuse ERP with Kanban; lastly build business process mixed by Pull-based mode and Plan-controlled mode. Through the above methods, ERP links with Lean to boost each other. Thus enable enterprise to gain a competitive advantage in manufacturing.