Peng Zhai

Kinetics of Cavitation Bubble in Ultrasonic Degassing of Casting Aluminium Alloy

Severe regassing was detected by previous experiment on degassing method for aluminium-silicon alloy by injecting argon with rotation. In order to further degas, ultrasonic degassing was adopted. To describe the cavitation bubbles’ movement, traditional Rayleigh-Plesset equation was modified. Classic Rayleigh-Plesset equation is strongly restricted by the applicable condition that the centre of the bubble is fixed. In this paper, a position-related Rayleigh-Plesset equation is proposed to describe the cavitation bubbles floating movement in aluminium-silicon alloy of 750°C with the coefficient of viscosity of 0.0012. As the calculation results, a bubble stimulated by high-low-frequency vibration can float up faster with violent vibration.

Theory research of seam recognition and welding torch pose control based on machine vision

At present, the automation requirement of the welding become higher, so a method of the welding information extraction by vision sensor is proposed in this paper, and the simulation with the MATLAB has been conducted. Besides, in order to improve the quality of robot automatic welding, an information retrieval method for welding torch pose control by visual sensor is attempted. Considering the demands of welding technology and engineering habits, the relative coordinate systems and variables are strictly defined, and established the mathematical model of the welding pose, and verified its feasibility by using the MATLAB simulation in the paper, these works lay a foundation for the development of welding off-line programming system with high precision and quality.

Algorithm of Transition Curve of Shaped Piston Cylindrical Cross Section

Piston is one of important parts of engine. It is meaningful to modify piston machining. The motion characteristics of shaped-piston cylindrical surface and profile were analyzed. A fitting transition curve method for the piston skirt cylindrical profile was proposed, which could satisfy requirements of smooth and non-impact, especially at the starting point and the ending point. And the machining profile data were generated by interpolating in Matlab. This result provides references for the piston design.

Identification Methods of Modified Prandtl-Ishlinskii Model for Giant Magnetostrictive Actuator

Modified Prandtl-Ishlinskii model is a phenomenological model widely used to characterize and compensate the hysteresis nonlinearity of piezoelectric material or magnetostrictive material. In addition, the identification method is the key section to determine the accuracy of the model. In this paper, mathematical principles of 3 identification methods are appealed and compared, then effects of the model are examined under 10Hz excitation frequency.

Design and Implementation of Measurement Instrument for Non-Cylinder Pinhole of Piston

For simplifying the cockamamie measurement process, in this paper, special equipment for measuring non-cylinder pinhole of piston is designed and implemented. First of all, the measuring principle, the hardware structure and the software system are illustrated. In addition, the measurement error is analyzed in detail. Finally, it is proved that the precision of the instrument is as high as that of the foreign advanced instrument.

Design of a Detecting System for the Welding Surface of Forging Steel Structure Piston Based on Ultrasonic

A new type of forging steel structure piston was introduced. Due to its features of structure and detection requirements, a detecting system used for the detection of its welding surface was designed, which is based on ultrasonic flaw detection technology. The probes posited under the end plane of the piston, facing accurately to the welding faces which contains of the inside ring and the outside ring. Using the longitudinal wave method after being water coupling, the detections can be detected. The detection theory, the hardware composition of the system, the software functions and the detection result were described in detail. The hardware structure of this system is simple and reliable; the software module is clear and stable and has very high flexibility, easy to modify and extend. The system has been applied to the actual production process, the performance has been verified. A nondestructive testing equipment of good performance for the forging steel structure piston’s quality control was provided.

Modified Prandtl-Ishlinskii Model for GMA of High-Load Pinhole Boring System

High-load pinhole is the key to improve the loading ability of power units. In this paper, a feedforward compensation method by modified Prandtl-Ishlinskii (P-I) model is proposed to characterize the hysteresis of Giant Magnetostictive Actuator (GMA) used on pinhole boring system, and the validation of model is examined by comparing the input-output relations of model and experimental data under 20Hz. Finally, a feedforward controller of inverse P-I model is designed to compensate the hysteresis. The experiments show hysteresis nonlinearity of GMA is reduced effectively under a wide frequency band from 21% to 2.3%.

An Improvement Design Research on the Structure of Precision Grinder

To increase the lower order natural frequency of MM7140 grinder’s support parts is an effective measure to improve structural rigidity, avoid resonance and reduce amplitude. The finite element models of MM7140s lathe bed and column, were established by 3-D software UG, and led into ANSYS for modal analysis. Then, found the column was the weak link based on the modal analysis results, and brought out the more effective improvement program. This paper offers a reliable basis for the design and renovation of MM7140 grinder.

Design of Ultrasonic Measurement System for BRRPO

Bonding rate of ring and pistons ontology (BRRPO) is used to describe the bonding quality of inserted ring and pistons ontology. According to the basic principle of ultrasonic flaw detection, shape of inserted ring and nature of material, penetration method is utilized to detect the bonding quality. An ultrasonic measurement system is designed. The design consists of hardware and software. Controlling process of hardware has been designed legally and made the detection precise. The design of software, based on VC++, consists of accomplishment of basic functions, such as data collection and data processed, and some special functions, such as automatic detection.

Study on Hi-Power Precision Driving Power of Giant Magnetostrictive Actuator Based on Power Amplifiers

According to the driving characteristics of giant magnetostrictive material and the principle of constant current source analysis, the continuously adjustable driving power was developed by adopting the principle of constant current, selecting power operational amplifier, and using parallel flow technology to expand its output current, which had a large current, large output power, high efficiency and low power consumption. And through the actual test, the driving power of giant magnetostictive actuator reveals a good performance.