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1 – 10 of 12
Article
Publication date: 16 August 2013

Qinglong An, Dapeng Dong, Xiaohu Zheng, Ming Chen and Xibin Wang

The objective of this study is to develop an automated tool condition monitoring scheme for PCB drilling.

Abstract

Purpose

The objective of this study is to develop an automated tool condition monitoring scheme for PCB drilling.

Design/methodology/approach

Vibration signals are used to distinguish micro drill wear stages with proper features extraction and classifier design. Then a tool condition monitoring system is built up through a back propagation neural network (BPNN).

Findings

Experimental results show that BPNN is a practical method of modeling tool wear, and with this method a tool condition monitoring system is built up using energy ratio, root mean square (RMS) and kurtosis coefficient that transformed by vibration signals.

Research limitations/implications

In the further investigation, more signal samples should be computed as monitoring features for BPNN modeling. In addition, in order to build the best monitoring model, it is necessary to evaluate the performance of the BPNN model in advance, and optimize the process.

Originality/value

The paper provides a method and a system for PCB drill wear monitoring. The method and system can achieve on‐line monitoring of PCB drill condition.

Article
Publication date: 18 November 2013

Xiaohu Zheng, Dapeng Dong, Lixin Huang, Xibin Wang and Ming Chen

– The paper aims to investigate tool wear mechanism and tool geometry optimization of drilling PCB fixture hole.

Abstract

Purpose

The paper aims to investigate tool wear mechanism and tool geometry optimization of drilling PCB fixture hole.

Design/methodology/approach

An experimental study was carried out to investigate the chip formation and tool wear mechanism of drilling PCB fixture holes. Two types of drill with different types of chip-split groove were used in this study. The performances of these two types of drill bots were evaluated by tool wear and the shapes of chips.

Findings

The chips of drilling fixture holes contain aluminum chips from the cover board, copper chips from the copper foil, discontinuous glass fiber and resin from the CFRP. Feed rate and drilling speed have a great influence on the chip morphology. Abrasive wear of the drill lip is the main reason of the fixture drill bit in drilling PCB, and micro-chipping is observed on the tool nose and chisel edge. The influence of distance between the chip-split groove and drill point center on the axial force and torque is not obvious.

Research limitations/implications

In this paper, hole wall roughness and drilling temperature were not analyzed in the optimization of drilling parameters. The future research work should consider them.

Originality/value

This paper investigated the mechanism of burr formation and tool wear in drilling of PCB fixture holes. Tool geometry was optimized by adding chip-split grooves.

Details

Circuit World, vol. 39 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Content available
Article
Publication date: 18 November 2013

Martin Goosey

211

Abstract

Details

Circuit World, vol. 39 no. 4
Type: Research Article
ISSN: 0305-6120

Article
Publication date: 6 December 2018

Zhen Yan, Dong Jiang, Xiaoming Gao, Can Zhang, Ming Hu, Dapeng Feng, Jiayi Sun, Lijun Weng and Chao Wang

This paper aims to study the tribological behavior of the WS2/oil-impregnated porous polyimide (PPI) solid/liquid composite system, in which both PFPE (perfluoropolyether) and…

Abstract

Purpose

This paper aims to study the tribological behavior of the WS2/oil-impregnated porous polyimide (PPI) solid/liquid composite system, in which both PFPE (perfluoropolyether) and SiCH (silahydrocarbons) oils with different hydrocarbon chains were used, respectively. Lubricating mechanism of the composite system was also explored.

Design/methodology/approach

The tribological behaviors of the WS2 films against the PPI cylindrical pins before and after immersing oil were evaluated under different loads by a reciprocating-type ball-on-disc tribometer.

Findings

The composite system exhibited the low and stable friction coefficient after the running-in stage, and the lubricant oil played a positive effect. It was found that the WS2/PFPE composite system exhibited more excellent lubricating property, although sole SiCH far exceeds PFPE in lubrication. The abnormal phenomenon mainly resulted from the influence of the oil amount. XRD results on the wear track surfaces indicated that PFPE and SiCH oils with different hydrocarbon chains were likely to preferentially adsorb to the edge plane and basal plane of the WS2 crystals, respectively.

Originality/value

In previous studies, liquid lubricants were directly dripped or spin-coated on the solid lubricant surface. Based on its potential advantage in application, the tribological behavior and mechanism of the solid lubricating film/oil-impregnated PPI composite system were investigated in this study.

Details

Industrial Lubrication and Tribology, vol. 71 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 4 August 2021

Chenglong Yu, Zhiqi Li, Dapeng Yang, Hong Liu and Alan F. Lynch

This study aims to propose a novel method based on model learning with sparsity inducing norms for estimating dynamic gravity terms of the serial manipulators. This method is…

188

Abstract

Purpose

This study aims to propose a novel method based on model learning with sparsity inducing norms for estimating dynamic gravity terms of the serial manipulators. This method is realized by operating the robot, acquiring data and filtering the features in signal acquisition to adapt to the dynamic gravity parameters.

Design/methodology/approach

The core principle of the method is to analyze the dictionary composition of the basis function of the model based on the dynamic equation and the Jacobian matrix of an arm. According to the structure of the basis function and the sparsity of the features, combined with joint-angle and driving-torque data acquisition, the effective features of dynamic gravity parameters are screened out using L1-norm optimization and learning algorithms.

Findings

The theoretical analysis revealed that training data obtained based on joint angles and driving torques could rapidly update dynamic gravity parameters. The simulation experiment was carried out by using the publicly available robot model and compared with the previous disassembly method to evaluate the feasibility and performance. The real 7-degree of freedom (DOF) industrial manipulator was used to further discuss the effects of the feature selection. The results show that this estimation method can be fully operational and efficient in industrial applications.

Research limitations/implications

This approach is applicable to most serial robots with multi-DOF and the dynamic gravity parameters of the robot are estimated through learning and optimization. The method does not require prior knowledge of the robot arm structure and only requires joint-angle and driving-torque data acquisition under low-speed motion. Furthermore, as it is a data-driven-based method, it can be applied to gravity parameters updating.

Originality/value

Different from previous general robot dynamic modelling methods, the sparsity of the analytical form of dynamic equations was exploited and model learning was formulated as a convex optimization problem to achieve effective gravity parameters screening. The novelty of this estimation approach is that the method does not only require any prior knowledge but also does not require a specifically designed trajectory. Thus, this method can avoid the laborious work of parameter calibration and the induced modelling errors. By using a data-driven learning approach, the new parameter updating process can be completed conveniently when the robot carries additional mass or the end-effector changes for different tasks.

Details

Industrial Robot: the international journal of robotics research and application, vol. 48 no. 6
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 19 April 2013

Dong Jiang, Litian Hu and Dapeng Feng

The purpose of this paper is to design the crown‐type phosphate ionic liquid additive which can dissolve in poly(ethylene glycol) (shortened to PEG) completely, and evaluate the…

Abstract

Purpose

The purpose of this paper is to design the crown‐type phosphate ionic liquid additive which can dissolve in poly(ethylene glycol) (shortened to PEG) completely, and evaluate the tribological properties as additive in PEG for steel/steel contacts.

Design/methodology/approach

To improve the solubility and the tribological performance of ionic liquid additive in PEG, the crown‐type phosphate ionic liquid additive was prepared. The tribological properties of the crown‐type phosphate ionic liquid additive in PEG were evaluated at different concentrations and rubbing frequencies on an Optimol SRV oscillating friction and wear tester. The morphology and chemical compounds of the wear scars were analyzed by scanning electron microscope (SEM) and X‐ray photoelectron spectroscopy (XPS).

Findings

The experimental results show that the crown‐type phosphate ionic liquid additive applied in based oil exhibits better tribological properties for steel/steel contacts at different loads, concentrations and rubbing frequencies. It could improve the anti‐wear ability and reduce the friction coefficients as the increased concentration. By the SEM and XPS analysis, it is found that there were the effective boundary lubricant films in the worn surface. The boundary films were composed of various tribochemical products, ferric oxide, ferric phosphate and pyrophosphate, together with the absorbed films.

Originality/value

Compared with the poor miscibility of some ionic liquid in PEG, the crown‐type phosphate ionic liquid additive can dissolve in PEG perfectly. It can improve the anti‐wear ability and reduce the friction coefficient of PEG at different concentrations and rubbing frequencies.

Details

Industrial Lubrication and Tribology, vol. 65 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 14 June 2013

Dong Jiang, Litian Hu and Dapeng Feng

The purpose of this paper is to synthesize a novel kind of crown‐type phosphate ionic liquids with better tribological properties for steel/Al system. The anions of crown‐type…

Abstract

Purpose

The purpose of this paper is to synthesize a novel kind of crown‐type phosphate ionic liquids with better tribological properties for steel/Al system. The anions of crown‐type phosphate ionic liquids contain no F element, which are non‐corrosive to metal.

Design/methodology/approach

To improve the tribological properties of ionic liquid lubricants for the extremely difficult system of the steel‐against‐aluminum metal couple, novel crown‐type phosphate ionic liquids were prepared. The tribological properties of the crown‐type phosphate ionic liquids were evaluated at different loads and frequencies on an Optical SRV oscillating friction and wear tester. The morphology and chemical compounds of the wear scars were investigated by scanning electron microscope (SEM) and X‐ray photoelectron spectroscopy (XPS).

Findings

Compared with conventional ionic liquids, the novel crown‐type phosphate ionic liquids prepared in the present work exhibit a more excellent anti‐wear ability for steel/Al2024 contact at different loads and frequencies. By the morphological analysis with SEM, less debris was observed in the worn surface lubricated with crown‐type phosphate ionic liquids, though more debris was observed when lubricated with LB106 and LP106. By the XPS analysis, boundary lubrication film composed of aluminum (III) oxide, organometallic compounds, and silicon aluminum phosphate were found in the worn surface. Namely, the tribological behaviors of the crown‐type phosphate ionic liquids could be attributed to their stronger adsorption and tribochemical interactions with the Al alloys.

Research limitations/implications

Because of the higher mean friction coefficients of crown‐type phosphate ionic liquids in the research, researchers are encouraged to modify their structure for better tribological properties.

Practical implications

The crown‐type phosphate ionic liquid exhibited better anti‐wear performance for steel/aluminum contact than the conventional ionic liquids containing F element. This will expand the application of high strength aluminum alloys.

Originality/value

The phosphate ionic liquid is a non‐corrosive liquid and would not cause metal corrosion. Also, the tribological properties of crown‐type phosphate ionic liquid with steel/aluminum contact are better than that of conventional ionic liquids. By the designing of molecular structure, new phosphate ionic liquids will exhibit excellent tribological properties: lower wear volume and lower friction coefficient.

Details

Industrial Lubrication and Tribology, vol. 65 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 24 September 2019

Xianggang Zhang, Dapeng Deng and Jianhui Yang

The purpose of this paper is to establish the horizontal displacement angle limit values under different performance level, use damage as the quantitative index of performance…

Abstract

Purpose

The purpose of this paper is to establish the horizontal displacement angle limit values under different performance level, use damage as the quantitative index of performance level and determine the design principle of the RACFST column for performance-based seismic fortification target based on the damage.

Design/methodology/approach

The paper is based on the seismic performance test of the RACFST column.

Findings

First, three-level seismic are introduced into the performance design foundation of the RACFST column. Second, the performance level of the RACFST column is divided into five grades: normal use, temporary use, use after repair, life safety and prevention of collapse. Third, the seismic performance targets of RACFST columns are divided into four categories: unacceptable situation, basic performance target, important performance target and special performance target.

Originality/value

The initial damage of the recycled aggregate occurs in the process of crushing and screening, and the damage evolution and development of the RACFST column occur under cyclic load. This is one of the problems that should not be avoided in the design of the seismic performance of the RACFST column. New levels are introduced in the performance design foundation of the RACFST column.

Details

International Journal of Structural Integrity, vol. 11 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 7 June 2021

Dapeng Zhang, Xinbo Sun, Feng Tian and Shunyi Zhou

The internet-based transition is the major trend for Chinese organizations with increasing demands imposed on their organization and management. As the organizational structures…

Abstract

Purpose

The internet-based transition is the major trend for Chinese organizations with increasing demands imposed on their organization and management. As the organizational structures gradually improve flexibility, employees desire respect and development to a greater degree, which has given rise to a new leadership model-integrative leadership. This paper aims to investigate the impact of integrative leadership on employee’s innovation performance through a multilevel analysis.

Design/methodology/approach

This paper proposes the two situational factors employee psychological empowerment and human resource flexibility as the mediating factors impact the relationship between integrative leadership and employee innovation performance. Valid questionnaires were collected from 619 employees from 135 leader groups of High-tech companies in China.

Findings

The results show that integrative leadership has positive impact on employees’ innovation performance through its multilevel impacts on two mediation factors include psychological empowerment of employees and human resource flexibility.

Research limitations/implications

This research used cross-sectional studies due to constraints of research conditions. The measurements of all variables are done simultaneously, whereas the effects of integrative leadership on the development of corporations should be presented in a dynamic process. Therefore, in the future research, vertical research design should be adopted to deeply explore the effectiveness mechanism of integrative leadership in the context of corporate internet-based transition.

Practical implications

In the internet era, leaders cannot blindly pursue organizational performance. They must establish a flexible organizational structure and institutions to provide a platform for employee development, and integrative leaders need to pay attention to inspire the potential of employees and stimulate the enthusiasm of employees.

Originality/value

This study investigates a new leadership-integrative leadership and the relationship between integrative leadership and innovation performance in the context of Internet-based transitional Chinese organizations, thereby making important theoretical contributions as well as offering practical suggestions for improving leadership efficiency and innovation performance.

Article
Publication date: 14 September 2010

Wang Haisu and Fang Zhongxiu

The paper aims to examine the similarities of fast‐growth private enterprises (PEs) in China with particular focus on enterprises listed on growth enterprises market in order to…

505

Abstract

Purpose

The paper aims to examine the similarities of fast‐growth private enterprises (PEs) in China with particular focus on enterprises listed on growth enterprises market in order to draw managerial implications for other PEs.

Design/methodology/approach

The paper looks at the release effects of intangible assets in PEs. It examines the excavation effects of preferential policy on PEs and goes on to discuss the agglomeration effects of the inherent advantages of these.

Findings

The paper argues that the fast growth of PEs in our sample was attributable to three main factors, i.e. benefits of intangible assets marketisation, shrewd use of government preferential policies and technological and managerial capabilities.

Practical implications

This research calls for the Chinese Government to adjust relevant policies to create a fair and competitive environment for enterprises with different ownerships and different scales.

Originality/value

The paper highlights the fact that the social and economic conditions of China in the post‐transition period have changed greatly and that the Chinese Government needs to clarify and define the existing characteristics and functions of enterprises and improve their service‐oriented functions.

Details

Journal of Chinese Entrepreneurship, vol. 2 no. 3
Type: Research Article
ISSN: 1756-1396

Keywords

1 – 10 of 12