Research On Mechanism And Key Technologies Of The Ultrasonic Feeder

The traditional electromagnetic vibration feeder is restricted to the production occasions of high cleaning and low noise due to unfavorable factors, such as serious magnetic interference, severe work noisy and so on. One of the most effective solutions to reduce the noise is to adopt the drive mode except sonic vibrations; while the most radical solution to solve the magnetic interference problem is a non-magnetic drive mode. And the piezoelectric actuation is precisely meeting the above requirements.The ultrasonic vibration feeder developed in this paper is under the support of Chinese Natural Science Foundation program"The driving mechanisim and study of ultrasonic vibration feeder", and national 863 program"The research and development of vertical-driven-piezoelectric feeder". Because of ultrasonic actuation traditionally applied to the electrical and acoustic fields, its mechanical drive capability was known only in recent years. Ultrasonic motor is a successful example of ultrasound-driven applications, and current study of ultrasonic actuation is focused on motor direction yet. So ultrasonic vibration to the feed can be seen as further development and application of ultrasound-driven capability, which through reasonable structure form ultrasonic vibration to drive the system, so that the surface of feed plate's movements are superimposed or combined and finally form elliptical motion, enabling it to promote the materials contacting with them continuous movement, it is active exploration of ultrasonic actuation technology in handling material direction.1. The research purpose of ultrasonic feederAs an indispensable part of production line, automatic feeding device determines the pros and cons of automated production processes to a large extent and thus we call high requirements on its structure, noise, working principle, delivery precision. Because of vibration is vibration feeders'intrinsic properties during its work, the only way to reduce noise is to adopt the drive mode except sonic vibrations, and the use of ultrasonic vibration may be the best choice to solve this problem. Ultrasonic Piezoelectric vibration feeder is more quiet, lower altitude ,smooth delivery, lower electro-magnetic interference, better array performance, lower prices, faster response speed than the traditional electro-magnetic and low frequency Piezoelectric vibration feeder, it's what the current vibration feeder can not match.2. Design of piezoelectric transducerUltrasonic transducer has many different types according to vibration mode, the direction of stretching vibration and piezoelectric conversion mode, depending on the different applications, we choose a different structure of piezoelectric vibrator, and they have their own features respectively. This article discusses the basic technical theory of the vibration mode of ultrasonic transducer, and in accordance with relevant analysis and calculation, we select the piezoelectric ultrasonic transducer of bolt-type fastening of the vertical vibration mode; design and calculate its structural parameters; analyze the transducer vibration mode by ANSYS software; test the resonant frequency and impedance of the designed transducer by precision impedance analyzer and measured the end amplitude of the transducer by experiments. The results of principle analysis and experimental verification tells us that the ultrasonic piezoelectric transducer can meet the design requirements of ultrasonic feeders in the regard of the operating frequency, electromechanical conversion efficiency, transmission power, the output amplitude and so on.3. The modeling and simulation of kinetics, kinematics of ultrasonic feederIn this paper, we present a new type of ultrasonic vibration feeder prototype and determine the vibration of the basic structure of the feed device; based on the analysis of the structure of ultrasonic vibration to the feeding mode to enhance the driving capacity, we focuses on the effects of the materials and the structure of the major components to ultrasonic feeder. Through the establishment of ultrasonic feeder's mechanical model and the analysis of the system's dynamic part, we obtain the mathematical relationship between the natural frequency and vibration frequency of the system. We established ultrasonic vibrating feeding system's dynamics model, analyzed the relationship between the natural frequency and vibration frequency by ANSYS software and carry out the kinetic analysis to guide the structural design of the various components, manufacture and the assembly of the ultrasound feeder prototype. Through the establishment of differential equations of motion of materials, the analysis of the conditions how material can slip and jump in feed tray, the scope of the working abilities of the feeder can be determined. Through the establishment of kinematics mathematical model of material conveyor, the analysis of the formation mechanism of elliptical motion, the analysis of the trajectories of the feed tray particle using ANSYS software, we verified the works of ultrasonic vibration feeder. Through the analyses and experiments of drag reduction mechanism of ultrasonic suspension, the establishment of the relevant motion equations, we analyzed the affect of drag-reducing on the ultrasonic suspension feeder's drives capacity.4. The structural design and specificity analysis of ultrasonic feederOn the basis of the above mathematical analysis and FEM simulation, the design of base, feed tray, support parts and flexible connecting piece were optimized. The performance parameters of the various parts of the ultrasonic feeder were determined and the ultrasonic feeder's structure was further optimized on the basis of the assembly, approach and cross-experiment. Through the establishment of equivalent circuit of the system, the resonant characteristics of the system were analyzed and calculated. On the basis of the test of the relationship between ultrasonic feeder's resonant frequency and impedance characteristics by various methods, we obtained ultrasonic vibration feeder's impedance phase characteristic values under the state of resonance, further more the new method of using direct phase method to track the resonant frequency ultrasound was proposed. Through the establishment of mathematical model of ultrasonic feeder, the impedance matching meaning, matching methods and performance were studied and based on comparing several matching methods, the impedance matching program was determined.5. The design of ultrasonic piezoelectric digital controllerBy the works of ultrasonic feeders, only under the resonant state, ultrasonic feeders performs good transmission capacity. Since factors like material quality in feed tray changes, the resonant frequency of ultrasonic feeders is shifted. Therefore, the drive power of ultrasonic feeder needs to have the ability to track its resonant frequency. Based on the above analysis of the feeder, a dedicated digital drive power was designed for the ultrasonic feeder, which uses DSP as control core, uses inverter topology and uses transformer-isolated output. We have modeled and analyzed the topology structure of the main circuit, designed the circuit of resonant frequency tracking and control and the control software, conducted a test and performance analysis on the drive power.6. The research on the performance of the ultrasonic feederA prototype of a new ultrasonic feeder has been made, and has done some experiments. The results showed that ultrasonic feeder has the ability to make feed tray promote materials continuous moving by the longitudinal vibration of ultrasonic transducer, and under the resonant state can get the best transmission capacity. Experiments show that when working frequency is 15.3 kHz, spring thickness is 5mm, the conveyor speed of metal sheets of diameter of 3mm can get up to 6mm per second, at the same time, as the piezoelectric ultrasonic-based driven mode, the possibility of electromagnetic interference and noise was eliminated theoretically. It has been proved that, the ultrasonic feeder is able to form elliptical motion of elastic surface body, thus obtains capabilities to promote material movement with a well-designed structure which synthesizes one or more ultrasonic vibrations on an elastomer to make them vibrate in accordance with a plan mode. And frequency-tracking experiment proved that, under the changing conditions, ultrasonic feeder could work stably in the vicinity of the resonant frequency with the drive power automatically tracking the changing resonant frequency.