Automatic press-fit assembly of small precision interference fitting parts: armature of electro-hydraulic servo valve

2019 ◽  
Vol 39 (5) ◽  
pp. 986-998
Author(s):  
Xingyuan Wang ◽  
Zhifeng Lou ◽  
Xiaodong Wang ◽  
Yue Wang ◽  
Xiupeng Hao ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Quality Assessment ◽  
Calibration Method ◽  
Technical Problems ◽  
Content Type ◽  
Press Fit ◽  
Automatic Press ◽  
Assembly Accuracy ◽  
The Press ◽  
Methodological Guidelines

Purpose The purpose of this paper is to design an automatic press-fit instrument to realize precision assembly and connection quality assessment of a small interference fitting parts, armature. Design/methodology/approach In this paper, an automatic press-fit instrument was developed for the technical problems of reliable clamping and positioning of the armature, automatic measurement and adjustment of the attitude and evaluation of the connection quality. To compensate for the installation error of the equipment, corresponding calibration method was proposed for each module of the instrument. Assembly strategies of axial displacement and perpendicularity were also proposed to ensure the assembly accuracy. A theoretical model was built to calculate the resistant force generated by the non-contact regions and then combined with the thick-walled cylinder theory to predict the press-fit curve. Findings The calibration method and assembly strategy proposed in this paper enable the press-fit instrument to achieve good alignment and assembly accuracy. A reasonable range of press-fit curve obtained from theoretical model can achieve the connection quality assessment. Practical implications This instrument has been used in an armature assembly project. The practical results show that this instrument can assemble the armature components with complex structures automatically, accurately, in high-efficiency and in high quality. Originality/value This paper provides a technical method to improve the assembly quality of small precision interference fitting parts and provides certain methodological guidelines for precision peg-in-hole assembly.

An improved vision calibration method for coaxial alignment microassembly

2014 ◽  
Vol 34 (3) ◽  
pp. 237-243 ◽  
Author(s):  
Xin Ye ◽  
Jun Gao ◽  
Zhijing Zhang ◽  
Chao Shao ◽  
Guangyuan Shao
Keyword(s):  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Vision System ◽  
Image Plane ◽  
Calibration Method ◽  
Corner Detection ◽  
Objective Lens ◽  
Content Type ◽  
Assembly Accuracy ◽  
Methodological Guidelines

Purpose – The purpose of this paper is to propose a sub-pixel calibration method for a microassembly system with coaxial alignment function (MSCA) because traditional sub-pixel calibration approaches cannot be used in this system. Design/methodology/approach – The in-house microassembly system comprises a six degrees of freedom (6-DOF) large motion serial robot with microgrippers, a hexapod 6-DOF precision alignment worktable and a vision system whose optical axis of the microscope is parallel with the horizontal plane. A prism with special coating is fixed in front of the objective lens; thus, two parts’ Figures, namely the images of target and base part, can be acquired simultaneously. The relative discrepancy between the two parts can be calculated from image plane coordinate instead of calculating space transformation matrix. Therefore, the traditional calibration method cannot be applied in this microassembly system. An improved calibration method including the check corner detection solves the distortion coefficient conversely. This new way can detect the corner at sub-pixel accuracy. The experiment proves that the assembly accuracy of the coaxial microassembly system which has been calibrated by the new method can reach micrometer level. Findings – The calibration results indicate that solving the distortion conversely could improve the assembly accuracy of MSCA. Originality/value – The paper provides certain calibration methodological guidelines for devices with 2 dimensions or 2.5 dimensions, such as microelectromechanical systems devices, using MSCA.

Micro-assembly precise coaxial alignment methodology based on surface roughness and reflectiveness matching

2014 ◽  
Vol 34 (2) ◽  
pp. 141-150 ◽  
Author(s):  
Yong-long Tang ◽  
Zhi-jing Zhang ◽  
Xin Ye ◽  
Xiao-feng Zhang
Keyword(s):  
Surface Roughness ◽  
Micro Electro Mechanical System ◽  
Alignment Error ◽  
Mems Devices ◽  
Content Type ◽  
Micro Assembly ◽  
Assembly Accuracy ◽  
Optical Alignment ◽  
Micro Structures ◽  
Methodological Guidelines

Purpose – The purpose of this paper is to propose a novel method of coaxial optical precision alignment based on surface roughness and reflectiveness matching. Design/methodology/approach – The micro-assembly experiment system set-up was constructed according to the principle of the coaxial optical alignment. The coaxial optical alignment error is theoretically analyzed and calculated. When the prism orthogonal alignment mechanism produces the error of 0.001°, the theoretical deviation was less than 0.87 μm and the actual experimental micro-assembly platform assembly accuracy exceeded 3 μm. A peg-in-hole precise assembly of punching pin micro-assembly experiment was done in order to validate feasibility of this method. Findings – The results indicate that coaxial optical precision alignment could be used for the assembly of complex micro-heterogeneous system which is integrated by similar devices, such as 3D complex micro-structures, silicon micro-electro-mechanical system (MEMS) devices and non-silicon MEMS devices with flat structure. Originality/value – The paper provides certain methodological guidelines for MEMS for high precision automatic assembly of complex 3D micro-structures.

Farm wages and public works

2015 ◽  
Vol 8 (1) ◽  
pp. 19-72 ◽  
Author(s):  
Kanika Mahajan
Keyword(s):  
Theoretical Model ◽  
Wage Rate ◽  
Fixed Effects ◽  
Positive Impact ◽  
Wage Growth ◽  
State Level ◽  
Random Allocation ◽  
Farm Sector ◽  
Content Type ◽  
The Impact

Purpose – The purpose of this paper is to examine the impact of National Rural Employment Guarantee Scheme (NREGS) on farm sector wage rate. This identification strategy rests on the assumption that all districts across India would have had similar wage trends in the absence of the program. The author argues that this assumption may not be true due to non-random allocation of districts to the program’s three phases across states and different economic growth paths of the states post the implementation of NREGS. Design/methodology/approach – To control for overall macroeconomic trends, the author allows for state-level time fixed effects to capture the differences in growth trajectories across districts due to changing economic landscape in the parent-state over time. The author also estimates the expected farm sector wage growth due to the increased public work employment provision using a theoretical model. Findings – The results, contrary to the existing studies, do not find support for a significantly positive impact of NREGS treatment on private cultivation wage rate. The theoretical model also shows that an increase in public employment work days explains very little of the total growth in cultivation wage post 2004. Originality/value – This paper looks specifically at farm sector wage growth and the possible impact of NREGS on it, accounting for state specific factors in shaping farm wages. Theoretical estimates are presented to overcome econometric limitations.

Intention to adopt mobile payment in physical stores

2019 ◽  
Vol 33 (2) ◽  
pp. 285-308 ◽  
Author(s):  
Yonathan Dri Handarkho ◽  
Yulius Harjoseputro
Keyword(s):  
Theoretical Model ◽  
Technology Acceptance ◽  
Switching Behavior ◽  
Mobile Payment ◽  
Herd Behavior ◽  
User Intention ◽  
Consumer Innovativeness ◽  
Content Type ◽  
Use Of Technology ◽  
Acceptance Model

Purpose The purpose of this paper is to develop a theoretical model based on Push–Pull–Mooring (PPM) framework consisting of direct, indirect and moderating effects, derived from technology acceptance model, unified theory of acceptance and use of technology and other extended theory, to address the main factor influencing an individual in adopting mobile payment (MP) in physical stores. The research, therefore, utilized individual switching behavior as an underpinning to explain MP adoption in an offline context. Design/methodology/approach The theoretical model was tested by collecting data from 459 respondents in Indonesia through online self-administered questionnaires. Findings The finding indicated consumer innovativeness has the most influential direct effect on MP adoption, followed by deal proneness, perceived convenience and perceived herd behavior. Meanwhile, perceived enjoyment and subjective norms were found to have an indirect effect on the adaptation of MP through mediator convenience. Furthermore, age, gender, occupation and income did not have any moderating effect for all the direct influence of MP adoption. Originality/value Previous literature only focused on direct intention. However, this study observed the adoption of MP in a physical store by involving the switching behavior. It specifically puts concern and objective as the factors that influence user intention to switch from their old payment system to the MP system in bricks and mortar store using PPM framework.

Does the hiring of chief risk officers align with the COSO/ISO enterprise risk management frameworks?

2017 ◽  
Vol 25 (3) ◽  
pp. 274-295 ◽  
Author(s):  
Erastus Karanja
Keyword(s):  
Risk Management ◽  
Enterprise Risk Management ◽  
Clear Understanding ◽  
Press Releases ◽  
Apparent Lack ◽  
Content Type ◽  
Business Operations ◽  
Enterprise Risk ◽  
The Press ◽  
Iso 31000

Purpose There are two main industry-sanctioned enterprise risk management (ERM) models, that is, COSO 2004 and ISO 31000:2009, that firms refer to when implementing ERM programs. Taken together, the two ERM models specify that firms should implement ERM programs to meet a strategic need, improve operations and reporting or to comply with government regulations or industry best practices. In addition, the focus of ERM implementation should be either the subsidiary, business unit, division, firm/entity or global level. The purpose of this study is to investigate whether firms are aligning their ERM implementations with these tenets: strategy, operations, reporting, compliance and the level of implementation. Design/methodology/approach The proxy for ERM implementation is the hiring of a Chief Risk Officer (CRO). The research data come from a sample of 122 US firms that issued a press release following the hiring of a CRO between 2010 and 2014. The press releases were retrieved and aggregated through content analysis in LexisNexis Academic. Findings The results reveal that many ERM implementations are occurring at the firm/entity level, and with the exception of reporting, firms consider ERM to be a strategic firm resource capable of improving business operations and compliance initiatives. Originality/value There is a dearth of research studies specifically investigating whether ERM programs adopted by firms are aligned with the specification of COSO 2004 and ISO 31000:2009 frameworks. The apparent lack of a clear understanding of the alignment between the firm ERM programs and the industry’s ERM frameworks may limit the development and implementation of ERM and the eventual realization of the benefits associated with a successful ERM implementation.

Deflation of metrizamide-filled balloon used to occlude a carotid-cavernous fistula

1983 ◽  
Vol 59 (3) ◽  
pp. 524-528 ◽  
Author(s):  
Thomas J. Leipzig ◽  
Sean F. Mullan
Keyword(s):  
Contrast Agent ◽  
Vascular Wall ◽  
Carotid Cavernous Fistula ◽  
Technical Problems ◽  
Content Type ◽  
Cavernous Fistula ◽  
Short Summary ◽  
Carotid Cavernous Fistulas ◽  
Fine Print

✓ A carotid-cavernous fistula was occluded by a detachable latex balloon. Because of technical problems, the contrast-filled balloon was left in a precarious position in the ostium of the fistula. Premature deflation of the balloon would have resulted in intra-arterial migration of the device. Approximately 1 week is required for the balloon to become secured in place by fibrous attachment to the vascular wall. For success, if the ligature is adequate, a detachable Debrun balloon should remain inflated for this period of time. The deflation process was monitored radiographically in this patient. The balloon remained inflated for at least 2 weeks. A short summary of the experience with deflation of various contrast-containing balloon devices in the treatment of carotid-cavernous fistulas is given. Metrizamide may be the best contrast agent for use in these devices.

Privacy helplessness on social media: its constituents, antecedents and consequences

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hichang Cho
Keyword(s):  
Theoretical Model ◽  
Structural Equation ◽  
Factor Model ◽  
Measurement Model ◽  
Equation Modeling ◽  
Confirmatory Factor Analyses ◽  
Content Type ◽  
Internet Users ◽  
The Usa ◽  
Antecedents And Consequences

PurposeMany internet users exhibit signs of privacy helplessness and entirely give up online privacy management. However, we know little about what privacy helplessness is, when users are likely to experience it and its implications for privacy behavior. The objectives of this study were twofold: (a) the conceptual explication of privacy helplessness as a novel construct in privacy research and (b) the development of a theoretical model that specifies the antecedents and consequences of privacy helplessness.Design/methodology/approachA research model of privacy helplessness that contains three subcomponents of privacy helplessness, five antecedents and one outcome was developed. The model was empirically examined based on survey data collected from 589 Facebook users in the USA.FindingsThe results of exploratory and confirmatory factor analyses showed that privacy helplessness is adequately assessed by a three-factor model with affective, cognitive and motivational components. The results of structural equation modeling indicated that these three aspects of privacy helplessness are uniquely predicted by five theoretical factors: (a) prior experience of privacy risks, (b) personal mastery, (c) perceived costs of adaptive privacy actions, (d) perceived rewards of privacy inactions and (e) perceived vulnerability. Furthermore, it was found that helplessness as motivational deficits (and cognitive helplessness via this) impedes adaptive privacy actions, while cognitive helplessness promotes adaptive privacy actions when they do not result in motivational deficits.Originality/valueThis study pioneers investigation in understanding key constituents, attributes and processes underlying privacy helplessness. First, the present study developed the first theory-derived, successively validated measurement model of privacy helplessness. Second, this research proposed a theoretical model of privacy helplessness, specifying antecedents and consequences of privacy helplessness.

Auszugverhalten von Schaftfräsern*/Pull-out behavior of end mills – Experimental study on different clamping devices with various clamping mechanisms

2018 ◽  
Vol 108 (05) ◽  
pp. 353-358
Author(s):  
E. Abele ◽  
F. Ali ◽  
M. Berger
Keyword(s):  
Experimental Study ◽  
Test Bench ◽  
Mechanical Load ◽  
Mechanisms Of Action ◽  
Heavy Duty ◽  
Press Fit ◽  
Pull Out ◽  
The Press ◽  
End Mills ◽  
Tool Position

Aus Schwerzerspanung und Turbinenschaufelfertigung ist bekannt, dass Werkzeuge aus dem Spannfutter ausgezogen werden. Die veränderte Werkzeugposition führt zur Abweichung von den vorgegebenen Toleranzen und einer geringeren Fertigungsqualität oder Beschädigung des Werkstücks. Der Artikel untersucht das Auszugsverhalten verschiedener Spannfutter. Mit einem Prüfstand können die Einflüsse der mechanischen Belastung und der Klemmlänge auf die Haltekraft im Pressverband betrachtet und die Wirkmechanismen beim Auszug des Werkzeuges aus dem Spannfutter sensorisch ermittelt werden.   From heavy-duty cutting and turbine blade manufacturing it is known that tools pull out from chucks. A change in tool position leads to deviations from tolerance and decreases manufacturing quality or damages the workpiece. This article explores the extension behavior of different chucks on a specifically designed test bench. This allows determining how mechanical load and clamping length influence the holding force in the press fit and what mechanisms of action affect the extraction of the tool from the chuck.

Consumer perception vs sensory assessment of the quality of clothes of selected brands available on the Polish market

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Renata Salerno-Kochan ◽  
Paweł Turek
Keyword(s):  
Quality Assessment ◽  
Sensory Quality ◽  
Brand Names ◽  
Survey Method ◽  
Quality Level ◽  
Sensory Assessment ◽  
Content Type ◽  
Significant Difference ◽  
Consumer Assessment

PurposeThe aim of the study reported in this article was to establish whether the quality of clothes of a given brand is perceived and assessed by consumers at the same level. An additional purpose was to identify the features that characterize the quality of popular, among Polish young female consumers, clothing brands and to classify them according to their quality level (perceived and assessed).Design/methodology/approachThe article presents two approaches to consumer assessment of the quality of clothes: the survey method, in which the product quality was determined by 320 Polish female young respondents (19–25) based on their own previous experiences and impressions related to a particular clothing brand, and a direct assessment of shirts of selected brands using a sensory quality assessment method, a five-point hedonic scale with the verbal anchor (115 evaluators).FindingsThe research has revealed a significant difference between the perception of selected quality features of brands and the consumer assessment of the products. The perception maps developed based on the PROFIT analysis (PROperty FITting) as well as on cluster analysis provided interesting information about the situation of selected brands and their features in comparison with others and allowed to identify strong and weak features characterizing a given category.Research limitations/implicationsThis study has several limitations. First and foremost, the research results cannot be generalized to all consumers because they encompass the results from one national context and one population of respondents (young females). It should also be noted that the conducted research comprises only the most popular clothing brands available on the Polish market, in particular, the fast fashion segment brands. Furthermore, it would be advisable to carry out a sensory assessment of the quality of other clothing items offered under the brand names investigated.Practical implicationsThis research could be a valuable source of information for clothing company managers, thanks to which they could better manage their brand and its position on the market. When undertaking marketing activities consisting of building positive perceptions about the product, it is important to make sure that the product offers an attractive sensory experience. When real quality deviates from consumer perceptions about the quality, managers should take corrective actions to restore and even improve the brand image in the eyes of the consumer, as well as to ensure the brand and the products offered under it a stable position on the market.Originality/valueBy comparing two approaches to consumer quality assessment, discrepancies between declared and real (sensory) quality of clothes have been identified and the distinctive features that differentiate selected brands regarding their quality level have been indicated.

Experimental study on the relationship between the friction coefficient and interference in locomotive axle press-fitting

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ting Wang ◽  
Hanfei Guo ◽  
Jianjun Qiao ◽  
Xiaoxue Liu ◽  
Zhixin Fan
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Friction Pair ◽  
Rolling Stock ◽  
Content Type ◽  
Press Fitting ◽  
The Press ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Locomotive Wheels

PurposeTo address the lack of data in this field and determine the relationship between the coefficient of friction and the interference between locomotive wheels and axles, this study evaluates the theoretical relationship between the coefficient of friction and the interference under elastic deformation.Design/methodology/approachWhen using numerical analyses to study the mechanical state of the contacting components of the wheels and axle, the interference between the axle parts and the coefficient of friction between the axle parts are two important influencing factors. Currently, as the range of the coefficient of friction between the wheel and axle in interference remains unknown, it is generally considered that the coefficient of friction is only related to the materials of the friction pair; the relationship between the interference and the coefficient of friction is often neglected.FindingsA total of 520 press-fitting experiments were conducted for 130 sets of wheels and axles of the HXD2 locomotive with 4 types of interferences, in order to obtain the relationship between the coefficient of friction between the locomotive wheel and axle and the amount of interference. These results are expected to serve as a reference for selecting the coefficient of friction when designing axle structures with the rolling stock, research on the press-fitting process and evaluations of the fatigue life.Originality/valueThe study provides a basis for the selection of friction coefficient and interference amount in the design of locomotive wheels and axles.

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