Key Engineering Materials Vol. 621

Abstract: The frequence and complex of space exploration activeities makes the life of the spacecraft and on-orbit service technologies becoming research hotspot in recent years. But the limitation of non-renewable fuels makes exploration mission costly and maintenance difficult, so the free floating space robot has its unique advantages. Because the research level and control technology is not maturity, study on the free floating space robot control method is the key theory and technology which is the difficulty that our country now needs to overcome, also, the research is of great theoretical and practical significance. This paper introduct an experiment scara mechanical arm based on the free floating space robot project. Main research contents of this paper include the mechanical structure design, and combining with the characteristic of the free floating mechanical arm , it makes kinematics and dynamics modals of the mechanical arm system, additional, it conduct statics test and dynamic modal analysis, which is to make sure that the mechanical arm could satisfy needs and to study its dynamic characteristics.This topic focus on structure design and mathematical modeling of the mechanical arm, it makes the research of control method and trajectory planning no longer stay on the paper, and makes the research more authenticity and accuracy.

Abstract: The production of rolling steel is a complicated process which includes management of production operations and production process. The former includes costs accounting, procurement plan of raw materials and auxiliary materials and quality control. The latter includes devices, technology and production rhythm of iron making, steel making, casting and rolling. Nowadays, the departments of these two have adopted the computer managing system to improve the efficiency of management. But the concept of collective design of CIMS is not considered thus the computer control system and operations management computer system are isolated. Furthermore, resources are not shared and information is not integrated among the systems thus enterprise competitiveness decreases. This paper designs the rolling steel computer aided manufacturing system based on internet and introduces the three levels system structure of CIMS technology strategy as well as the key technology. This study is of great significance not only in the integration of rolling steel production systems and the sharing information, but also in upgrading the steel enterprises, reducing costs and increasing enterprise competitiveness.

Abstract: Based on spiral bevel gear NC manufacture principle and generating motion of the generating gear and the work gear, the NC generation of spiral bevel gear cutting is realized by means of the vector transformation. As sophisticated calculation of the transformation is hard to implement in each interpolation cycle of NC machining, the coordinated motion of NC coordinate axes is expressed as quintic parametric spline functions, which use the rotation angle of the work gear as the parameter. The constrained optimization method of three design variables is established to obtain contacting points of gear tooth surfaces, which are acquired by solving nonlinear equations sets traditionally. The condition of normal coincidence is simplified and the object function of the equal position vectors of mating gears is established. The contacting points of gear tooth surfaces can be used for tooth contact analysis. The parametric curve interpolator is combined with spiral bevel gear NC machining, and is applied to the self-developed spiral bevel gear NC milling machine to control the gear cutting. Experimental results show that the proposed method is feasible and effective in the control of NC machining for the spiral bevel gear.

Abstract: On the basis of analyzing assembly process of main structural components in CA6140 lathe, 3D models for those components were established with CAD software UGNX6.0. Virtual assembly and motion simulation of the structure parts were performed with virtual technology. A set of virtual assembly system of CA6140 engine lathe was developed with programming software Visual Basic 6.0. It contains six main modules about spindle box, feed box, apron, tailstock, turret, etc. Dynamic simulation and motion simulation of the corresponding components in entity lathe can be realized, respectively. And also, mechanical structure, working principle, assembly relation between different components and motion transmission process of the lathe can be realistically reproduced with the system. This virtual assembly system not only can be used to analyze and transform old products, but also can be used in new products development, and to some extent, can be used to replace the prototype. It is an indispensable tool in the employee training and mechanical engineering activities.

Abstract: The drives of power amplifiers of magnetic levitation servo spindle applied to micro EDM (Electron discharge machining) based on FPGA (Field programmable gate array) are developed. The drive module that produces the PWM (Pulse width modulation) waves that conform to the requirements of spindle power amplifiers involving three-level half bridge switch power amplifier, three-level full bridge switch power amplifier and motor power amplifier, according to input of action values from magnetic levitation servo spindle controller DSP (Digital signal processor) is designed. Multi-PWM producing algorithm by single timer with multi comparing nodes is proposed. After being applied to control system of magnetic levitation servo spindle, the drives accomplish conversion from DSP action values to PWM waves. The PWMs that drive radial coil current power amplifier have phase difference of 180°. The PWMs that drive axial coil current power amplifier have dead zone time and their wave shapes are complementary. The PWMs that drive the motor power amplifier conform to requirements of power amplifier chip LMD18200. Using FPGA to realize the drive function of spindle power amplifier makes the drive design more flexible, resource distribution of DSP more optimized, the task of algorithms running more centralized, and the drives module gets simpler and more reliable because the phase shift circuit and dead zone circuit are cancelled but the function of phase shift and dead zone is reserved.

Abstract: Normal circular-arc spiral bevel gear is a new type gear based on Bertrand conjugation principle. Normal circular-arc bevel gear selects directrix on the basis of paying attention to machining planning process. When the directrix serves as loxodrome, the formed tooth profile surface not only has fine transmissibility like general arc bevel gear, but also is convenient to machining. Starting with differential geometry, the geometry nature and inner relationship of Bertrand conjugation surface are studied. Then the normal circular-arc surface id put forward which is a typical Bertrand surface; the conjugation theory of loxodrome normal circular-arc bevel gears is studied. The characters of loxodrome line are analyzed. The tooth profile of loxodrome normal circular-arc bevel gears, the primary condition the directrix line must be satisfied, the relative curvature of the conjugating surfaces, the relations between non-interventional condition and curvature axle of the directrix line is provided; the NC machining theory of normal circular-arc bevel gears is studied, including the designing and manufacture of the tool, the movement of the machine, the adjustment of the tool under the condition of tangency and non-interventional condition and so on.

Abstract: The technology of NC machining simulation is a reflection in virtual environment. Machining simulation may effectively reduce the invalid feeding and probability of interference or collision between cutter and fixture due to unreasonable machining parameters. Researches on machining simulation of multi-axis NC machining are complex and representativeness. This paper took a process of surface under NX CAM environment on a non-orthogonal five axis machine tool—DMU50eVolution as the object for machining simulation, by inputting the proper engagement for the cutter, using the method of coordinate transformation to create a post processor with UG post-builder and integrated into the library of post-processing. The NC codes created have been verified in the simulation system with VERICUT. And it has been shown that the preparation time of NC machining has been reduced, the efficiency of NC machining improved and the phenomenon of collision and interference effectively prevented.

Abstract: With digital development of modern manufacturing enterprises, requirements for production process control, resource scheduling and cost analysis are increasing. Enterprises are therefore required to manage the information and process in order to reduce cost and production time and improve quality of products and services. Information for a enterprise concerns orders, raw materials, technology, manufacturing process and products, with huge amount of data and complex correlations among data. Accordingly, data model of integrated production management system is complicated and difficult to develop. This paper analyzes technological document, production plan, production task, production cost and process and control of business activities. Method of building a complete set of information model and process model for manufacturing enterprises is presented, which makes modeling more effective and standardized. As one common method, the model driven approach is introduced to set up the database structure and development strategy of integrated production management system, which may reduce the workload and difficulty of development. Development of a system is realized and verified in practice.

Abstract: In order to fit the intelligent development of NC programming system, through in-depth study to master the internal structure and structural principle of NC turning center, this paper developed the innovative NC programming model using common G-code based on its original MAZATROL conversational programming capabilities, and further implements the G-code programming model embedded into its specified MAZATROL conversational programming model, which not only can reflect the versatility of the common G-code programming model, but also can bring into play simple and easy maneuverability of MAZATROL programming model; Finally, by running NC program to perform the trial turning test on NC turning center, the test results verify that the nested NC programming model developed by this paper can effectively solve the tedious and error-prone manual NC programming problem, which greatly reduces the programming and debugging time, improves utilization of NC machine tools, and ultimately has brought significant economic benefits. Therefore, the research results of the paper will provide a simple and effective and practical way to improve the programming efficiency, and have important application value to further enhance the programming intuitive research of NC turning center.

Abstract: In order to improve the real-time performance and accuracy of the traditional SRG(Seeded Region Growing) algorithm in image processing, this paper proposes a intellective and rapid image segmentation by imitating the process of the virus infection in nature, and then implement it on vc++6 platform. On one hand , the algorithm can detecting automatically detect the seeds in image region and can be adapt for uneven-light image by adjusting the parameters based on the brightness of the background; On the other hand, only by one of the image scanning, it can segment and mark the objects from the background. The experimental results show that compared with the traditional SRG algorithm, this algorithm can improve the segmentation speed in different background with higher accuracy.