Design And Experiment Of Automatic Lid Closing Machine For Cherry Tomato Packing Box

As people become more health-conscious,they are increasingly drawn to fresh fruits and vegetables that can be eaten directly,such as cherry tomatoes.However,getting these tomatoes from the field to the table involves multiple steps,which can lead to losses.To combat this,specific packaging boxes are often used to transport and sell cherry tomatoes.Currently,there is a lack of packing machinery specifically designed for cherry tomato boxes in the domestic packing machinery industry.As a result,the packing process is primarily done manually,which can lead to increased labor intensity and mental fatigue of workers.Moreover,this traditional method of packing is not in line with the current trend of using digital and intelligent packing solutions.In order to address the aforementioned issues,a kind of automatic lid closing machine specially used for cherry tomato packing box is designed in this paper.The primary focus of this research is outlined below,along with the resulting conclusions:(1)Overall scheme design of automatic lid closing machine.Through practical research,the models of the cherry tomato fruit packing boxes with the largest consumption and the widest demand in the current market are determined to be 500 M and 300 M respectively.With the above two models of packing boxes as the closing lid object of this design,the functional requirements and performance requirements of the automatic closing machine are proposed respectively.The working principle of the automatic closing machine is developed and six closing processes are determined: packing box conveying,uniform spacing,box lid leveling,box lid closing,lid clamping,finished product output.Considering the cooperative requirements of each actuator when the automatic lid closing machine works,the overall scheme of the automatic lid closing machine control system is designed.Based on the process flow and working principle,the design requirements of the automatic lid closing machine control system are proposed.Through comparative analysis,the micro-control unit,ultrasonic sensor and temperature and humidity sensor types of the control system are selected.Finally,the control system is determined to take the application layer,the operating system layer,the driver layer and the hardware layer as the system structure.(2)Design of actuator of automatic lid closing machine.In order to realize the requirements in the overall scheme of automatic lid closing machine,the automatic lid closing machine executive mechanism is determined to be composed of five key devices: the device of conveying packing box,the device of adjusting box lid posture,the device of closing the box lid,the device of clamping the box lid,and the device of conveyor chain.The electrical equipment in the actuator is mainly included in the device of conveying packing box,the device of closing the box lid and the device of conveyor chain.Considering the cost of the whole machine,the compatibility of the control system and the design difficulty,the selection of the governor,the frequency transformer,the electric putter and the DC power in these three devices is carried out respectively.In order to ensure the stability of the transmission process of the device of conveyor chain,the related selection and safety check of the transmission chain are carried out.The five devices in the actuator were modeled and the complete structure of automatic lid closing machine was assembled.(3)Hardware design of automatic lid closing machine control system.Based on STM32F103ZET6 chip,the hardware design of the control system is completed according to the function to be realized by the executive mechanism of automatic closing machine.The components of the minimum system circuit of STM32 controller are determined and the circuit design is carried out,including chip circuit,crystal oscillator circuit,reset circuit and power conversion circuit.According to the working principle and communication method of each electrical equipment and sensor in the actuator,the components of the peripheral circuit are determined and the principle analysis and circuit design are carried out,including ultrasonic sensor module circuit,DHT temperature and humidity sensor module circuit,OLED display module circuit,RS485 module circuit,PWM module circuit,electric relay module circuit.According to the minimum system circuit and peripheral drive circuit,the PCB design drawing and proofing are completed,and related electronic components are soldered on the PCB.(4)Software design of automatic closing machine control system.According to the function of hardware layer driver of automatic closing machine,based on Free RTOS real-time operating system multi-task management,complete the design and development of the control system software.The main process and the software implementation process of ultrasonic ranging program,temperature and humidity collection program,OLED display program,RS485 communication program,PWM driver program and relay driver program are expounded in the form of flow chart.Relevant codes are written for the development environment.(5)Trial production and verification test of automatic lid closing machine prototype.In order to verify the working performance of the automatic lid closing machine,according to the overall scheme of the automatic lid closing machine,the actuator and the software and hardware design,the prototype of the automatic lid closing machine is trial-produced and debuggable,and the verification test is carried out.The results show that: for the 500 M and300M model cherry tomato packing boxes,the automatic lid closing machine can successfully complete six processes;the closing success rate is 86% and 92%;the closing efficiency is 172 boxes /h and 184 boxes /h.The closing success rate is good and the efficiency is high,and the prototype is stable and reliable.