Xiaoyang Jiao

Nozzle and needle during high viscosity adhesive jetting based on piezoelectric jet dispensing

A piezoelectric impinging jet valve is used as a study object to investigate the effect of the ball needle in the existing impinging jet and nozzle structure of the valve on the performance of the jet. First, FLUENT software is used under different ball needle and nozzle structural parameters to simulate the pressure distribution that the ball needle and nozzle in the pressure cavity form when the ball needle hits the nozzle, by arranging the structure model of the ball needle and impact valve nozzle. The piezoelectric impact injection valve and the experiment test system are then designed. Test results show that the ball needle and nozzle structural parameters are closely related to the injection performance of the impact valve. Under certain conditions, a greater needle radius corresponds to a smaller nozzle aperture and taper. Moreover, high-viscosity liquid jetting is easily achieved. By using a ball needle with a radius of 1.5 mm, a taper angle of 60°, and a nozzle diameter of 0.1 mm, we can realize the industrial viscosity of 58 000 cps in glue spray, and the injection plastic fluid volume is 0.62 μl.

Performance study of standing wave levitation with emitting and reflecting surface of concave sphere structure

In order to improve levitation capability and stability of ultrasonic standing wave, a novel levitation device was presented, which adopted concave spherical surface on the emitter and the reflector. Using ANSYS software, the acoustic field generated by the concave spherical emitting surface was analyzed and the formation of ultrasonic standing wave was simulated. Based on the simulation result, the distribution and maximum acoustic pressure under different radius of concave spherical surface on the emitter and the reflector were ascertained. Through the MATLAB simulation, the optimal structural parameter and levitation position were predicted. Based on the optimization result, the prototype of standing wave levitation device was designed and manufactured. In the laboratory, the radiation force was tested and levitation experiments were also carried out and the actual levitation position was in accordance with the simulation results. When the distance between the emitter and the reflector equaled to about 34.9 mm, three steel balls of 3 mm diameter could be levitated at the same time in three disparate nodes position, the levitation capability and stability were demonstrated to be enhanced largely.

Design and Experiment of a Solder Paste Jetting System Driven by a Piezoelectric Stack

To compensate for the insufficiency and instability of solder paste dispensing and printing that are used in the SMT (Surface Mount Technology) production process, a noncontact solder paste jetting system driven by a piezoelectric stack based on the principle of the nozzle-needle-system is introduced in this paper, in which a miniscule gap exists between the nozzle and needle during the jetting process. Here, the critical jet ejection velocity is discussed through theoretical analysis. The relations between ejection velocity and needle structure, needle velocity, and nozzle diameter were obtained by FLUENT software. Then, the prototype of the solder paste jetting system was fabricated, and the performance was verified by experiments. The effects of the gap between nozzle and needle, the driving voltage, and the nozzle diameter on the jetting performance and droplet diameter were obtained. Solder paste droplets 0.85 mm in diameter were produced when the gap between the nozzle and needle was adjusted to 10 μm, the driving voltage to 80 V, the nozzle diameter to 0.1 mm, and the variation of the droplet diameter was within ±3%.

Simulation analysis and experimental study of the temperature characteristics of electromagnetic levitation

This paper aims to realize the electromagnetic levitation of experimental samples with low conductivity and high density at relatively low temperatures. The relationships among the temperature characteristics of an electromagnetic levitation device and the structural size of the induction coil, the size of the experimental sample, the levitation position, respectively, which were studied using Maxwell and ANSYS through simulation analysis. Simulation results show that the maximum temperature produced by the induction coil decreases with an increase in winding turns of a stable coil and increases in the half-taper angles of levitation and stable coils; increases with the levitation position, that is, the temperature of the levitation device is higher at the bottom than in other areas; and increases initially and then decreases with an increase in the radius of the levitation sample. Other parameters, such as the first winding radius of the levitation coil, the planar space between the levitation and stable coils, the winding spacing of coils, and the winding turns of the levitation coil, slightly influence the maximum temperature that the induction coil can provide. Furthermore, constructing an experimental platform allowed for the discovery of the relationships between the parameters of the induction coil and its temperature characteristics; these relationships are consistent with the simulation results. The spherical levitation sample with a radius of 5.1 mm reaches its maximum temperature of 853 °C after 55.65 s, thereby achieving the objective of melting when the first winding radius of the levitation coil is 17 mm, the planar space between the levitation and stable coils is 16 mm, the winding spacing of coils is 8 mm, the winding turns of the levitation coil are 3, the winding turns of the stable coil are 2, the half-taper angles of the levitation and stable coils are 15°, and the levitation position is 17 mm.This paper aims to realize the electromagnetic levitation of experimental samples with low conductivity and high density at relatively low temperatures. The relationships among the temperature characteristics of an electromagnetic levitation device and the structural size of the induction coil, the size of the experimental sample, the levitation position, respectively, which were studied using Maxwell and ANSYS through simulation analysis. Simulation results show that the maximum temperature produced by the induction coil decreases with an increase in winding turns of a stable coil and increases in the half-taper angles of levitation and stable coils; increases with the levitation position, that is, the temperature of the levitation device is higher at the bottom than in other areas; and increases initially and then decreases with an increase in the radius of the levitation sample. Other parameters, such as the first winding radius of the levitation coil, the planar space between the levitation and stable...

Analysis and experimental study on the effect of a resonant tube on the performance of acoustic levitation devices

The influence of a resonant tube on the performance of acoustic standing wave-based levitation device (acoustic levitation device hereinafter) is studied by analyzing the acoustic pressure and levitation force of four types of acoustic levitation devices without a resonance tube and with resonance tubes of different radii R using ANSYS and MATLAB. Introducing a resonance tube either enhances or weakens the levitation strength of acoustic levitation device, depending on the resonance tube radii. Specifically, the levitation force is improved to a maximum degree when the resonance tube radius is slightly larger than the size of the reflector end face. Furthermore, the stability of acoustic levitation device is improved to a maximum degree by introducing a resonance tube of R=1.023λ. The experimental platform and levitation force measurement system of the acoustic levitation device with concave-end-face-type emitter and reflector are developed, and the test of suspended matters and liquid drops is conducted. Results show that the Φ6.5-mm steel ball is suspended easily when the resonance tube radius is 1.023λ, and the Φ5.5-mm steel ball cannot be suspended when the resonance tube radius is 1.251λ. The levitation capability of the original acoustic levitation device without a resonance tube is weakened when a resonance tube of R=1.251λ is applied. These results are consistent with the ANSYS simulation results. The levitation time of the liquid droplet with a resonance tube of R=1.023λ is longer than without a resonance tube. This result is also supported by the MATLAB simulation results. Therefore, the performance of acoustic levitation device can be improved by introducing a resonant tube with an appropriate radius.

Non-contact transportation of heavy load objects using ultrasonic suspension and aerostatic suspension

In order to realize non-contact transportation of a heavy load object that is more than 3N at a stable speed, a new hybrid suspension transportation utilizing both ultrasonic and aerostatic suspension is put forward. The resonant frequency of the hybrid suspension system, the fixed position of transducer and the matching impedance are analyzed using ANSYS software, Eular–Bernouli beam theory and equivalent circuit principle of transducer, respectively. Several physical parameters that influence the driving ability of traveling wave are also analyzed. Based on the optimal results obtained, the prototype of hybrid suspension is designed and manufactured in the experiment. The experimental system result shows that the hybrid suspension utilizing both ultrasonic and aerostatic suspension can realize non-contact transportation of heavy load objects at the stable speed and experimental results coincide well with the theoretical analysis results. The test result shows that the transport speed of suspended objects under hybrid suspension is larger than that only under ultrasonic suspension. A 75 × 60 mm object of 432 g, with surface density of 96 kg/m2, is transported at the stable speed of 4.2 cm/s when excitation voltage is 300 V and inlet pressure is 0.15 MPa.