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Article
Publication date: 21 September 2012

R. Usubamatov, S.A. Adam and A. Harun

The purpose of this paper is to investigate the process of jamming of the hollow parts on the shaft and to derive a mathematical model for jamming in an assembly process.

Abstract

Purpose

The purpose of this paper is to investigate the process of jamming of the hollow parts on the shaft and to derive a mathematical model for jamming in an assembly process.

Design/methodology/approach

The mathematical model for jamming of parts on the shaft in an assembly process is based on the sizes, geometry, angular declination of part and shaft axes, and the frictional factor.

Findings

The equation for angular positional tolerance of coaxial parts and shafts, based on their geometry and sizes and leading to jamming, was derived.

Research limitations/implications

A mathematical model of parts jamming on the shaft is developed for assembly mechanisms. This research does not consider flexible deformations of components in assembly mechanisms, which results in the axis concentricity of part and shaft in the assembly process.

Practical implications

The results presented in the form of angular positional tolerance for coaxial parts and shafts based on their geometry and sizes make it possible to avoid the jamming of the parts. The results allow for formulating the angular positional tolerance of the assembly mechanisms that clamp the parts.

Originality/value

The proposed method for calculating the angular positional tolerance of coaxial parts and shafts for the assembly process should allow for increasing the reliability of the assembly process in the manufacturing industry.

Details

Assembly Automation, vol. 32 no. 4
Type: Research Article
ISSN: 0144-5154

Keywords

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Article
Publication date: 27 September 2011

Ryspek Usubamatov and K.W. Leong

The purpose of this paper is to investigate theoretically the process of jamming in the peg‐hole type parts and to derive a mathematical model of jamming.

Abstract

Purpose

The purpose of this paper is to investigate theoretically the process of jamming in the peg‐hole type parts and to derive a mathematical model of jamming.

Design/methodology/approach

The mathematical model of the jamming of the peg‐hole type parts in assembly process was performed and its boundary conditions, which lead to jamming, defined.

Findings

The equation of the critical angles of declination for the peg, which leads to the peg‐hole jam, was derived. The boundary condition of the angles of declination and the depth of the peg insertion into the hole were defined.

Research limitations/implications

A mathematical model is developed for rigid parts with a hole and for the peg clamped in the rigid assembly mechanisms. The research has not considered flexible deformations and stiffness of the assembly mechanisms, which result in the peg's declination in the assembly process.

Practical implications

The results are represented in the form of the peg's critical angles of declination and critical depth of insertion into the hole, which leads to jamming of the peg‐hole type parts to be assembled. On the basis of the obtained results, it is possible to formulate the tolerances of the declination angles for the assembly mechanisms, which clamp the peg‐type parts.

Originality/value

The proposed method calculating the critical angles of the peg's declination and critical depth of the peg's insertion into the hole for assembly of the peg‐hole type parts, enables one to increase the reliability of the assembly process in the manufacturing industry.

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Article
Publication date: 1 December 2005

S.R. Hillman, S.H. Mannan, R. Durairaj, A. Seman, N.N. Ekere, M. Dusek and C. Hunt

To investigate how jamming of particles in a solder paste varies as a function of the gap through which the particles flow, and to correlate this with skipping defects…

Abstract

Purpose

To investigate how jamming of particles in a solder paste varies as a function of the gap through which the particles flow, and to correlate this with skipping defects during the printing process.

Design/methodology/approach

Solder pastes with particle sizes of types 2, 3, 4 and 5 were sheared between the parallel plates of a rheometer. Jamming events that cause the solder particles to be forced against each other were detected by monitoring the electrical current flowing between the plates under a bias of 1.0 V or less. Solder paste printing trials were conducted with the same pastes, and solder paste skipping monitored.

Findings

Jamming was detected when the ratio of plate gap to largest particle diameter is reduced to a value between 3.8 and 5.0. Decreasing the gap further results in increased jamming. A strong correlation between levels of skipping and jamming was found.

Research limitations/implications

More extensive printing trials are required before rheometric jamming detection can be used to predict printing performance.

Practical implications

The common rule of thumb used in solder paste printing that the aperture width should be no smaller than 4‐5 particle diameters is justified.

Originality/value

This paper presents a new technique for detecting jamming events which are too brief to be detected using normal rheometric techniques, but which have long been thought to be responsible for stochastic skipping defects during printing. Evidence supporting the link between jamming and this type of defect is presented.

Details

Soldering & Surface Mount Technology, vol. 17 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 12 April 2011

R. Usubamatov, A. Usubamatova and M.Z.A. Muin

The purpose of this paper is to present an analysis and practical study of part jamming in the feeder of an automatic machine.

Abstract

Purpose

The purpose of this paper is to present an analysis and practical study of part jamming in the feeder of an automatic machine.

Design/methodology/approach

The reliability of the feeder is derived by the probability and reliability theories that consider jamming of the part in a system feeder machine.

Findings

The part jamming in the feeder depends on the deviations of the part and the feeder sizes and the part turn in the feeder, on velocity of part motion, and length of motion.

Practical implications

Derived the methodology for calculating reliability of feeders.

Originality/value

Originality is application of the probability and reliability theories for calculation of feeder's failing and connection with the machines work time.

Details

Assembly Automation, vol. 31 no. 2
Type: Research Article
ISSN: 0144-5154

Keywords

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Article
Publication date: 6 July 2015

Xinlong Wang and Shuai Song

– The purpose of this paper is to improve the tracking performance of the tracking loops under high dynamic and severe jamming conditions.

Abstract

Purpose

The purpose of this paper is to improve the tracking performance of the tracking loops under high dynamic and severe jamming conditions.

Design/methodology/approach

First, as the two dominant measurement error sources of the tracking loops, the thermal noise jitter and the dynamic stress error are thoroughly analyzed. Second, a scheme of adaptive tracking loops, which could adaptively adjust the order and the bandwidth of tracking loops, is proposed. Third, real-time detections of the vehicle dynamics and the carrier-to-noise density ratio, and the adaptive bandwidth of the carrier loop are presented, respectively. Finally, simulations are operated to validate the excellent tracking performance of the adaptive tracking loops.

Findings

Based on the principle of minimizing the measurement errors, the loop order and bandwidth are adaptively adjusted in the proposed scheme. Thus, the anti-jamming capability and dynamic tracking performance of the tracking loops could be effectively enhanced.

Practical implications

This paper provides further study on the method of improving the tracking capability under complexly applied conditions of high dynamics and severe jamming.

Originality/value

The detections of carrier-to-noise density ratio and vehicle dynamics are used to adaptively adjusting the loop order and bandwidth, which could not only improve the measurement accuracy but also ensure the stable operation of tracking loops.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 87 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

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Article
Publication date: 1 February 1989

G. Stylios and D.W. Lloyd

In garment manufacture, causes of sewability problems have to be identified so that remedial actions can be applied. In the case of seam pucker, establishing the cause of…

Abstract

In garment manufacture, causes of sewability problems have to be identified so that remedial actions can be applied. In the case of seam pucker, establishing the cause of the problem is not easy because many different variables can produce the same fault. Existing methods of identifying seam pucker due to structural jamming are tedious, time consuming and inefficient. A technique of producing structural jamming pucker in test seams and eliminating other causes of pucker has been established. This technique involves the attachment of a simple device onto the L and M sewability tester or in principle to any sewing action simulator. The device has proved to be a simple and cheap method of producing specimens for the assessment of structural jamming pucker.

Details

International Journal of Clothing Science and Technology, vol. 1 no. 2
Type: Research Article
ISSN: 0955-6222

Keywords

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Article
Publication date: 2 August 2011

Sigitas Kilikevicius and Bronius Baksys

The paper aims to investigate theoretically and experimentally the process of compliantly supported peg insertion into a bush for high‐speed assembly, when vibrations are…

Abstract

Purpose

The paper aims to investigate theoretically and experimentally the process of compliantly supported peg insertion into a bush for high‐speed assembly, when vibrations are provided to the bush in the axial direction, and to analyse the influence of the parameters of the dynamic system and excitation on the assembly process.

Design/methodology/approach

The mathematical model of parts vibratory insertion process is formed and the simulation is performed using a numerical computing software environment. The model includes inertia, compliance, dry friction, insertion speed and vibratory excitation. The three‐dimensional simulation of peg‐in‐hole insertion is accomplished using motion analysis software to test the influence of vibratory excitation on assembly failures, such as jamming and wedging. The experimental setup for the robotic vibratory assembly and the investigation methodology were presented. The experimental analysis of the vibratory insertion process of cylindrical parts with clearance is performed when the compliantly supported peg is inserted by the robot into the bush, which is excited in the axial direction.

Findings

The vibratory excitation allows preventing the balance between the insertion force and frictional forces and so to avoid jamming and wedging. It is advantageous to select such the frequency of vibrations under which the resonance state of the compliantly supported peg does not occur. The parameters of vibratory excitation and initial assembly state are defined which have the principal influence on the insertion duration and the success of the process. The experimental results show the applicability of the mathematical approach.

Research limitations/implications

The assumption is made that the chamferless rigid peg moves in a plane in respect of the rigid bush with a chamfer. Also, it is considered that there is no impact during the peg and bush contact. The dynamic and static friction coefficient between the parts is equivalent and the insertion speed is constant.

Practical implications

The results can be useful aiming to design the reliable high‐performance vibratory assembly equipment for peg‐hole type parts, which does not require sensors, feedback systems and control algorithms.

Originality/value

The proposed method of applying the vibratory excitation during the peg‐in‐hole insertion process allows to avoid jamming and wedging, and to minimize the duration of the process.

Details

Assembly Automation, vol. 31 no. 3
Type: Research Article
ISSN: 0144-5154

Keywords

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Article
Publication date: 1 June 2002

Ron Postle

The importance of fabric biaxial extension, in‐plane compression, shear and bending properties, have been widely recognised by textile scientists and engineers for the…

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Abstract

The importance of fabric biaxial extension, in‐plane compression, shear and bending properties, have been widely recognised by textile scientists and engineers for the evaluation of the three‐dimensional formability and drape of textile materials in apparel products and three‐dimensional preforms. In contrast to woven fabrics where bending and shear properties determine the fabric formability, knitted fabrics have very high formability as a direct result of their easy biaxial extension properties. This ability to form three‐dimensional shapes using the biaxial extensibility of knitted structures enables these knitted textile materials to be utilised for a wide variety of close fitting apparel garments and shaped composite preforms. Some representative biaxial extension curves for the plain knitted structure are described in this paper. These curves illustrate an unusual shape for the load‐extension curve of a textile material arising from the pre‐tension or pre‐stress. The pre‐stress yields an initial high tensile modulus for the structure in contrast to the very low initial modulus characteristic of apparel textiles. Accordingly, for knitted textile materials, it is shown how biaxial extension of the fabric introduces a fabric pre‐stress to maximise the three‐dimensional fabric formability especially when subjected to transverse compression by the resin or matrix in a composite material. Typical uniaxial and biaxial tensile stress–strain curves for knitted fabrics are compared.

Details

International Journal of Clothing Science and Technology, vol. 14 no. 3/4
Type: Research Article
ISSN: 0955-6222

Keywords

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Article
Publication date: 26 January 2010

Yu Jie, Wang Xinlong and Ji Jiaxing

The purpose of this paper is to improve the tracking performance of the carrier phase lock loop (PLL) in the strapdown inertial navigation system/global positioning system…

Abstract

Purpose

The purpose of this paper is to improve the tracking performance of the carrier phase lock loop (PLL) in the strapdown inertial navigation system/global positioning system (SINS/GPS) integrated system with an innovative scheme of ultra‐tight integration.

Design/methodology/approach

First, providing the Doppler frequency for PLL using SINS velocity could enlarge the loop equivalent bandwidth and reduce the dynamic effect on the carrier loop. Meanwhile, lowering the filter bandwidth could increase the immunity to noise. Second, the relationships between the PLL and SINS errors have been analyzed, and then the PLL error model is established to eliminate the correlation between the pseudo‐range‐rate error and SINS velocity error. Third, the carrier frequency is regulated to improve the tracking accuracy, according to the error estimations of Kalman filter.

Findings

The innovative ultra‐tightly integrated system could not only enhance the anti‐jamming capability and the dynamic tracking performance of the tracking loops, but also improve the pseudo‐range‐rate measurements accuracy for the integrated filter.

Originality/value

This paper provides further study on the method of enhancing the carrier‐tracking performance and improving the integration mode in the ultra‐tightly integrated system based on the software‐defined GPS receiver.

Details

Aircraft Engineering and Aerospace Technology, vol. 82 no. 1
Type: Research Article
ISSN: 0002-2667

Keywords

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Article
Publication date: 1 January 1989

G. Stylios and D.W. Lloyd

The present work has shown that the cause of seam pucker in structurally jammed fabrics is mainly due to the sewing tensions of the sewing threads and that the fabric…

Abstract

The present work has shown that the cause of seam pucker in structurally jammed fabrics is mainly due to the sewing tensions of the sewing threads and that the fabric instead of trying to take up a more jammed configuration, as believed so far, tries to resist jamming and in doing so, buckles out of the fabric plane. The proposed mechanism of seam pucker is based on quantitative and qualitative studies of fabric and thread properties in relation to sewing. The stitch can be regarded as an Euler column consisting of three springs representing a lockstitch seam; a compressed spring in the middle representing the fabric, and two stretched springs either side of it representing the needle and bobbin threads. If the bending and compressional loads are high compared to the bending and compressive stiffness of the fabric, buckling will occur. If the column is stiff by comparison with these loads, then the critical load for the column will not be exceeded and buckling will not occur.

Details

International Journal of Clothing Science and Technology, vol. 1 no. 1
Type: Research Article
ISSN: 0955-6222

Keywords

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