Xiao Diao Huang

Research on Damping and Vibration Characteristic of the Large and Precision NC Rotary Table

According to the current situation of acicular chip and high-frequency chattering of the NC rotary table while gear milling, rigidity and damping performances of the table were analyzed and the damping program of Coulomb friction was bring up. Online test of the gear milling cutting force can be used to establish dynamic model of circumferential vibration of the table with Coulomb friction. Then mechanism of restraining gear cutting chatter by damping of Coulomb friction and acicular chip generating mechanism were exposed. Furthermore, relationship between backlash and rotary rigidity of the table was also analyzed. A kind of floating apparatus with friction damping was designed to optimize circumferential damping of the table by adjusting Coulomb friction force, which reduces the influence of high-frequency chattering on gear milling. As a result, efficiency of gear milling was increased 1.5 times and the noise was reduced from 105dB to 91dB.

Research on Process Parameter Optimization of the High-Neck Flange Closed Rolling Based on the Orthogonal Experimental Design

This paper simulates the process of the high-neck flange closed rolling on DEFORM-3D and optimizes the rolling process parameter by analyzing the results based on the orthogonal experimental design. For the high-neck flange, the results show that the effects on ellipticity are in the order of the mandrel feed speed, the main roll rotational speed and initial blank temperature. The former two factors show the significance while the initial blank temperature does not show that.

Power Skiving Process for Cylindrical Gears Manufacturing

Latest research clearly demonstrates the excellent capability of the gear power skiving technology. For further improvement of the skiving process and enhancement of the process reliability the fundamental research on the cutting mechanism of cylindrical gear power skiving was conducted. First the kinematic model of power skiving and mathematical equations of cutter were established according to the engagement principle of crossed helical gears. Then, based on the proposed model, we investigated the simulation process, chip deformation mechanism and the cutter top relief angle. The results support the skiving cutter design and process optimization and are an important basis for the implementation of the advanced gear process.

An Inspection Method of SMD Component Type Based on Moment Features and BP Neural Network

The type inspection of surface mounted devices (SMD) components is an important part of the numerical control (NC) placement machine’s vision system. In order to improve the detection speed, accuracy rate and versatility, a detection method based on moment features and neural network is proposed. Firstly, component images are preprocessed in order to eliminate the influence of non-uniform illumination and simplify the calculation, so component lead images can be obtained, and then seven invariant moments and a zero-order Zernike moment of the lead images are extracted. Next, the moment features are corrected and normalized. Finally, back propagation (BP) neural network based on the Levenberg-Marquardt algorithm is taken as a classifier for training and testing the 8-dimensional mixed moment feature vectors, 0 and 1 are used to represent the degree of belonging of each image. The experimental results show that this method doesn’t need complex lighting system and has good versatility, and the correct rate can be up to 100%.

A Novel Denoising Method Based on Ensemble Empirical Mode Decomposition – Principle Component Analysis

Equipment performance degradation model is a key component in its diagnosis and prognosis models. As to slewing bearing, vibration signals are usually non-stationary and with strong white noise, which makes it very difficult to extract useful information from the signals. Therefore, an Ensemble Empirical Mode Decomposition – Principle Component Analysis (EEMD - PCA) based method was proposed to denoise the vibration signals and performance degradation model was established by PCA. To verify the proposed method, an experiment was conducted and the life cycle vibration signals were acquired. After denoising, performance degradation model was established to explain the denoising performance. Results show that the proposed method acquired a better denoising performance than EEMD-MSPCA, which provides a potential for further research.

Structure Fatigue Life Analysis of a 1.5MW Smart Yaw Slewing Bearing

As an important rolling connection of the wind turbine, yaw slewing bearing plays a critical role in the structure reliability. Therefore, effective health monitoring of a slewing bearing to execute timely maintenance or replacement have attracted significant interest. In order to monitor working conditions on line, various sensors have been used. This paper discussed the installation approaches of various sensors in a yaw slewing bearing, and analyzed the effect of local structure change on the fatigue life of a 1.5MW slewing bearing by MSC.FATIGUE, and thus providing an effective reference for structural design of a smart slewing bearing.

BP Neural Network in Prediction of the Constant-Current Hydrostatic Bearing Static Stiffness

SKZT3500 NC rotary table adopts constant-current hydrostatic bearing and unloading guide two sets of hydraulic system. Aiming at the characteristics of two sets of hydraulic system, this paper deduces the constant-current hydrostatic bearing static stiffness formula. Then, the theory and algorithm of BP neural network were applied to predict the constant-current hydrostatic bearing static stiffness, based on experimental measurements in a physical prototype and neural network toolbox of MATLAB. Testing results show that BP neural network can accurately forecast the constant-current hydrostatic bearing of the static stiffness.

Influence of Friction on the Vibratory Response of Structure

Friction is a phenomenon caused by relative motion, which can be used to absorb vibrational energy. The influence of friction on vibration responses of structures is complex due to the complicacy and nonlinear of the friction itself. In this paper, a 3-DOF spring-damper model with/without friction force was studied to expose how the friction governed the vibratory responses. Several popular friction models were reviewed and LuGre Model was used in this paper. The vibration properties under sine excitation and random were simulated by the Matlab Simulink Software. The results showed that friction absorbed vibration well and vibration damping was rapid. The characteristics of friction influence resulted from comprehensive functions of all factors, such as types of excitation, excitation amplitude and frequency and the location of friction.

Study on Indexable Inserts for Gear Gasher

This document explains and demonstrates the gear gasher and the mechanism of the process. It is wildly applied, since the manufacturing precision can reach grade 9 to grade 8. The gear gasher composes indexable inserts, gasher body and bolts. Then the dimensions and the installation between the body and the inserts are specified and optimized, based on the cutting profile and cutting condition. The calculated model’s allowance is more even and total area allowance is smaller than the present’s. It can be used for the gasher fabrication.

Analysis of Dynamic Characteristic of Numerical Remanufacture Machine's Feeding System

In this paper,the ball screw feeding system’s dynamic characteristics of a numerical remanufacture grinding machine is analyzed using the FEM. Discusses the modeling method of ball screw system into the finite element model and established the combination of finite element model. Through the modal analysis and the harmonious response analysis, the nature frequency and vibration mode of the feeding system and typical operating conditions of excitation in the harmonic responsehave have been gotten,thus the dependable basis for the construction’s optimization and dynamic function’s increasing of the feeding system is provided, ensure the numerical remanufacture will be success.