| In order to solve the packaging machine shortage problem in the fresh food packaging areas,a kind of negative pressure type fresh food packaging machine were proposed,including the packaging process analysis and whole structure scheme design,with reference to the study of the fresh food packaging technology and machinery at home and abroad.The key equipment of conveying device,cutting mechanism and negative pressure transverse sealing device was analyzed theoretically and experimentally to determine structural forms and optimization parameter.The negative pressure type fresh food packaging machine realized high speed and high quality packaging for fresh food.The main research contents and conclusions were as follows:(1)According to the present situation of fresh food packaging machine in China,this paper put forward the design requirements and technical parameters of fresh food packaging machine,and analyzed the packaging process.And the structure characteristics and working principle of fresh food packaging machine were determined.Based on the requirements of the the fresh food packaging machine,the drive system and the key parameters of each mechanism were designed and calculated.(2)The conveying device of packaging machine were studied by simulation and experiment.Through compression test of PET packaging boxes and the finite element simulation,the process and mechanism of the compression deformation of the packaging boxes were analyzed.Then the easy damage position of the packaging boxes and the reason were determined.According to the orthogonal test analysis of the influence factors,the optimal parameter combination was found out.Under the condition of optimal parameter,there were no compressed damage on packaging boxes and fresh food.Meanwhile,a good transport synchronization was occurred between PET packaging boxes and conveying device.(3)A cutting mechanism of packaging machine based on the linkages and the cam mechanism was proposed.Firstly,by using the virtual prototype of ADAMS,the parametric model was established.And the influence of the main parameters on the motion of the mechanism was obtained.Depending on the analysis method of SQP algorithm,the optimal aggregative index was obtained.In this situation,the kinematic simulation analysis shows that the maximum value of acceleration of the lower cutter was 7971 mm/s2,and the cutting distance was 20.4 mm.Finally,based on the above parameter,the cutting rate of test prototype was above 98%for the PVC film with thickness of 11,12,13 um.(4)A negative pressure transverse sealing device was designed.The device adopts the negative pressure sucking and capturing film to realize the transverse sealing operation,which consists of front air suction box,rear air suction box and conveyor.The operation mechanism of the negative pressure transverse sealing device was studied.And the structure and working parameters of the device were determined.The quadratic orthogonal rotation combination experiment of three factors were carried out.Meanwhile,depending on the analysis of MATLAB,the optimal aggregative index was obtained,and the maximum value of the transverse sealing rate was 99.5%.The regression equation can be used to analyze and predict the performance of the sealing device.(5)The trial-produce and experiment of negative pressure type fresh food packaging machine were completed.The prototype test showed that:the packaging speed was 49.4 pack/min,the packaging rate was 99.4%,and the swell rate was 5%.The fresh food packaging machine with negative pressure type has met the design requirement and anticipated goal. |
