Papers by Author: Zhen Yu Han

Abstract: Automatic tape laying is a widely-used fabricating process for fiber-reinforced composite materials in aerospace and aviation industry. To fulfill the tape laying process, it is necessary to cut the prepreg tape into designated shape accurately and promptly. In this paper, a scheme of ultrasonic cutting bench is put forward to investigate the parameters of ultrasonic cutting process. The functional requirements are analyzed and the key components of ultrasonic cutting bench, such as transverse feed mechanism of cutter, revolving gear of cutter, and mechanism for precision positioning of cutting depth, are presented in detail, which lays a solid foundation for future experimental research.

Abstract: Automated fiber placement (AFP) is a recent development of composite manufacturing technology and is widely used in the field of aerospace. The post processing of AFP has an important influence to the stability of machine movement and the manufacturing accuracy. This paper presents a post processing algorithm of a kind of 7-DOF gantry-type automated fiber placement equipment. The linking coordinates are set up according to the structure of the machine. To solve the redundant degree problem, pose separation method is adopted to calculate the inverse kinematics of the spindle rotation DOF and the other six movement DOFs of the manipulator respectively. Finally, reasonable parameters of each motion of the machine are obtained by the proposed post-processing method.

Abstract: A review of methods used for fault recognition of the rolling elements in gearbox, namely gear and bearing, is presented in this paper. The procedure of the fault recognition can be classified into three phases, which are data acquisition, data processing or important features extraction, and the fault mode detection. Many different methods have been developed in dealing with each phase, so that the arrangement of the entire process has different strategies. This paper summarizes some general used and recently popular developed methods of each phase, and makes comparison between them. This work also aims at giving a perspective in such area in the future, based on the known researches.

Abstract: This paper outlines a conceptual framework of STEP-NC manufacturing system, which integrates the entire manufacturing process including CAD, CAPP, CAM and CNC, to make full use of the advantages of the new generation of data model. The STEP-NC manufacturing system consists of five parts and the STEP-NC standard is used to transport the complete product information. The intelligent CNC in this system can parse STEP-NC program directly so that no translation is needed and the part programs are reusable. Networked manufacturing can be realized by implementing this new framework of STEP-NC manufacturing system.

Abstract: Micro-end-milling tools are suitable for machining miniature parts which have complex shape. As the diameters of tools are too small, cannot directly obtain the frequency response functions (FRFs) through impact hammer test at tool tip. This paper employs Receptance Coupling method (RC), couple the tool tip’s FRFs with machine-toolholder system’s FRF, and then get the micro-end-milling tool’s FRF. Establish the coupling model, then finite element and hammer test of the blank gauge tools are used to obtain the coupling transfer functions (TFs). Then analyze the tool tip model by finite element, couple with the machine-toolholder system hammer test result and coupling transfer functions, finally the micro-end-milling tool’s FRFs are obtained. Through the hammer test of blank gauge tool, the effectiveness and feasibility of RC method are verified. The result shows that the RC method is accurate at micro-end-milling tool in steady state milling.

Abstract: Currently machine tools and strategies researched in micro-milling field universally cannot be applied to 3D meso-scale parts machining directly, so great importance should be attached to the research on 5-axis machine tools and the suitable strategies for 3D meso-scale machining. This paper introduced a self-made 5-axis machine tool and several micro-milling strategies which were applicable to 3D meso-scale parts machining. Using these strategies, a mini impeller was successfully machined on the 5-axis machine tool developed independently. The experiment result showed the machine tool and the strategies were suitable for machining meso-scale 3D parts.

Abstract: The numerical control (NC) program files need re-generating if there is any tool dimension change or tool wear for multi-axis machining. If the tool is replaced to adapt this change there will be increased cost. To solute this problem, 3D cutter radius compensation method for 5-axis computer numerical control (CNC) machining is deeply researched. Taking five axes linkage machine tools of X, Y, Z, B, C form with rotary tables B and C as an example, coordinate transformation matrix (CTM) and the cutter compensation vector for 3D cutter radius compensation are derived. The discrimination methods for path joint pattern (PJP) are given. A controller with 3D cutter radius compensation function for 5-axis linkage CNC machine tools is developed based on this method. The controller is allocated to a 5-axis milling machine tool and experiments are done. The proposed algorithm is demonstrated using a practical example.

Abstract: For the application of STEP-NC in NC system, an STEP-NC code translator is exploited. Firstly, summarizes the limitation of conventional standard ISO6983 and the superiority of STEP-NC. After an analysis on two different generating methods of STEP-NC program, introduces the exploited STEP-NC code translator based on ISO14649. According to inner logical relation, the code translator is composed by six functional modules, an operating principle chart is presented, function and realizing method of every module is disserted on. At last, exampled with a program which includes planar face, pocket, slot, Bezier surface and replicate feature of round hole, planning the whole toolpath of the program using extracted information about workingstep, feature and operation by the exploited STEP-NC code translator. A cutting simulation is made to the toolpath and the workpiece model. The result proves the feasibility of the STEP-NC code translator.

Abstract: The theory of composite material patch winding is proposed to determine the winding trajectory by a meshed data model. The bridge condition on the concave surface is considered in this work. This paper puts forward the judgmental principles and corresponsive solutions by applying differential geometry theory and space geometry theory. To validate the feasibility of the patch winding method, the winding control code is programmed. Furthermore, the airplane inlet winding experiments are carried out.