Safety Analysisl Of Rapid Die Change System Of Skin Stretch-forming Machine

Stretch forming is the basic method for aircraft sheet metal,and the skin stretch-forming machine is the main equipment for aircraft skinning production.Due to the wide variety of aircraft skins and small production batches,it's necessary to change the mold frequently during the process of production.At present,the domestic mold replacement is still a traditional method that the mold changing time is long and the process of changing is cumbersome,which seriously affects the utilization rate of the machine.In addition,the research on solving the problem on the changing mold of skin stretch-forming machine is not sufficient in domestic.Therefore,the research on the process of changing the mold of this machine has practical engineering significance.For a domestic aircraft manufacturing company,our research group proposed a rapid mold change system for the FET-1200 skin stretch-forming machin,which can solve the problems existing in the current mold change process.In this paper,the safety of the mold change system is verified by the finite element method,and use the safety analysis method to analyze the safety of the system from the entire system.At first,this paper introduces the production status of the skin stretch-forming machine.Then,the fast mold change system of this machine with the rapid mold change technology as the core is introduced in detail,and the operation characteristics of this system are analyzed.By using this mold change system,the mold change time can be shortened from the first 20-40 minutes to 5 minutes.In order to ensure the structural reliability of the structure in the rapid mold change system and the structural reliability during the skinning process,this paper establishes a finite element simulation model of the mobile-workbench and the sliding-platform in ABAQUS,and then check the strength according to the relevant working conditions.Considering this problem that the discontinuity in the track during the switching between the preparation area and the work area for the mobile-workbench,this paper uses ABAQUS to simulate the motion process.And then according to the relevant rail vehiclesafety assessment criteria,study the effect of different degrees of partial load on its operational safety to the mobile-workbench.The analysis results show that the larger the partial load of the mobile-workbench,the greater the wheel load shedding rate,but always lower than the limit value of 0.6.The larger the partial load of the mobile-workbench,the smaller the anti-overturn coefficient,but always within the safety limits,and the larger side carrying is more prone to tipping.The analysis results show that the mobile-workbench is safe to operate during the discontinuous orbital process.Finally,the article analyzes the security of the fast mold change system from the perspective of system security.According to the failure mechanism of this mold change system for the skin stretch-forming machine,the fault tree analysis method can be used to analyze the possible failure factors in the system.And then briefly put forward the possible problems in the system and propose the corresponding solutions.