On the Design of the Open/Close Blow-Station Cam Mechanism of A Rotary Type Blow-Molding Machine

• Main Authors: Guo-Bin Wang, 王國賓
• Other Authors: Hong-Sen Yan
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/45888316451960418008

碩士 === 國立成功大學 === 機械工程學系碩博士班 === 94 === The manufacture efficiency and stability of rotary type PET bottle blow-molding machines are determined by the blow-station device. This device consists of blow-stations, cams, and blow-station linkage mechanisms, in which, the combination of the blow-station, the blow-station linkage mechanism, and the open/close blow-station cam mechanism is called the blow-station cam-linkage mechanism. When the blow-forming process of the blow-station device is progressing, the cam-linkage mechanism drives the blow-station to generate open/close motion. The design of motion curve of the cam for open/close blow-station cam affects the kinematic characteristics of the blow-station and the efficiency of the blow-forming process. Hence, in order to improve the performance of the rotary type blow-molding machine, this work targets on the design of the open/close blow-station cam mechanism for a rotary type blow-molding machine provided by a local industry. First, the vector loop method and Newton’s laws of motion are used to develop the mathematical models for the kinematic analysis and kinetostatic analysis of the inverse blow-station cam-linkage mechanism. Based on the design requirements and constraints of motion of the blow-station, by applying basic cam motion curves (MS, MT, MCV) to design the motion of the blow-station, the kinematic and kinetostatic characteristics of the blow-station linkage mechanism and the input force of the cam mechanism are derived. Then, by using the Bezier curve integrated with ALM optimum design approach, the feasible cam motion curve used to design the motion of the blow-station is obtained. And the kinematic and kinetostatic characteristics of the blow-station linkage mechanism and the input force of the cam mechanism are improved. Finally, according to the theory of envelope and the definition of pressure angle, the profile of the cam mechanism is synthesized and the pressure angle of the cam mechanism is analyzed. The motion curve of the cam designed by Bezier curve integrated with optimization design approach improves the kinematic discontinuous of the blow-station during the blow-forming process. The impulse force at the interface between the open/close phases of the blow-station is also eliminated. As the result, the joint forces from the blow-station linkage mechanism to the frame, the input force of the open/close blow-station cam mechanism, and the pressure angle are decreased. Furthermore, a Time Sequence Design Program is developed under the Visual Basic 6.0 software and is used to design the time sequence of the cams of the blow-station device. The Visual Basic software integrated with OpenGL simulation environment is applied to develop the OpenGL Motion Simulation Program. This program simulates the relative motion between the blow-station cam-linkage mechanism, the infeed preform cam-linkage mechanism, and the outlet bottle cam-linkage mechanism. This program is used to verify the motion of the proposed design. In summary, the motion curve designed by Bezier curve integrated with optimum design approach improves the kinematic and kinetostatic characteristics of the blow-station of the blow-molding machine, eliminates the impulse force at the interface between the open/close phases, and decreases the pressure angle and input force of the open/close blow-station cam mechanism. And, the result of this work successfully decreases the vibration and noise of the blow-molding machine and increases the productivity of the blow-molding machine form 8000 bottle/hour to 11000 bottle/hour, i. e., an improvement of 37.5%.