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Article

Emel Ceyhun Sabir and Erdem Koç

The main purpose of the study is to develop a theoretical model being capable of analysing the sealing and hydrodynamic‐hydrostatic lubrication mechanisms occuring between…

Abstract

Purpose

The main purpose of the study is to develop a theoretical model being capable of analysing the sealing and hydrodynamic‐hydrostatic lubrication mechanisms occuring between the mating surfaces of mechanical face seals.

Design/methodology/approach

The theoretical model developed is based on solving the governing basic lubrication equation (Reynolds differential equation) by employing a finite difference method. The main lubrication machanism is assumed to be converging‐diverging wedge which is formed by the relative tilt of the sealing surfaces. The non‐dimensional Reynolds equation was solved to give the pressure distribution and consequently the load and moment acting on the movable seal ring. The aim of the model is to predict the non‐dimensional hydrodynamic and hydrostatic load carrying capacity of the system.

Findings

Theoretical model developed is capable of estimating the hydrodynamic and hydrostatic behaviour of mechanical radial face seals. It is shown that a converging‐diverging wedge mechanism produces hydrodynamic pressure which in turn maintains the seperation of the surfaces. The tilt appears to be caused mainly by bearing misalignment. It has been shown that hydrostatic load or pressure centre is an important parameter for load balance of moving seal ring. It is easy and useful to calculate the dimensional parameters defined taking into account the different geometrical and operating parameters.

Originality/value

This paper offers a quick and easy opportunity to examine the hydrodynamic behaviour of movable seal ring of a mechanical face seal and provides a considerable contribution to the lubrication and sealing research area. With the general theoretical model developed, the behaviour of the seal ring can be modelled and estimated.

Details

Industrial Lubrication and Tribology, vol. 59 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

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Article

Fazıl Canbulut, Cem Sinanoğlu, Şahin Yıldırım and Erdem Koç

A neural network is employed to analyze axial piston pump of hydrostatic circular recessed bearing. Owing to complexity of the system, the neural network is used to…

Abstract

A neural network is employed to analyze axial piston pump of hydrostatic circular recessed bearing. Owing to complexity of the system, the neural network is used to predict the bearing parameters of the experimental system. The system mainly consists of cylinder block, piston, slipper, ball‐joint and swash plate. The neural model of the system has three layers, which are input layer with one neuron, hidden layer with ten neurons and output layer with three neurons. It can be outlined from the results for both approaches neural network could be modeled bearing systems in real time applications.

Details

Industrial Lubrication and Tribology, vol. 56 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

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Article

Fazil Canbulut, Cem Sinanoğlu and Erdem Koç

The purpose of this paper is to investigate experimentally slippers, which have an important role on power dissipation in the swash plate axial piston pumps. Since…

Abstract

Purpose

The purpose of this paper is to investigate experimentally slippers, which have an important role on power dissipation in the swash plate axial piston pumps. Since slippers affect the performance of the system considerably, the effects of surface roughness on lubrication have been studied in slippers with varying hydrostatic bearing areas and surface roughness.

Design/methodology/approach

An experimental set‐up was designed to determine the performance of slippers, which are capable of increasing the efficiency of axial piston pumps, in different conditions.

Findings

The findings suggest that the frictional power loss has been caused by surface roughness, capillary tube diameter, and the size of the hydrostatic bearing area, supply pressure and the relative velocity. In the case of the 0.7 and 9.5 μm surface roughness more power is needed to overcome the friction force between slippers and slipper plates, but less power loss occurs with the slippers with surface roughness of 1.5 μm. The slippers with surface roughness of 1.5 μm are considered, because of the optimum power loss. Moreover, the power loss decreases with increasing capillary tube diameter and supply pressure.

Originality/value

In order to investigate slipper behaviour under different operating conditions, with different capillary tube size and supply pressure an experimental work was carried out for finding exact design parameters of the real time system.

Details

Industrial Lubrication and Tribology, vol. 61 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

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Article

Fazil Canbulut, Erdem Koç and Cem Sinanoğlu

The purpose of this paper is to experimentally and theoretically investigate slippers, which have an important role on power dissipation in the swash plate axial piston pumps.

Abstract

Purpose

The purpose of this paper is to experimentally and theoretically investigate slippers, which have an important role on power dissipation in the swash plate axial piston pumps.

Design/methodology/approach

The slipper geometry and working conditions affected on the slipper performance have been analyzed experimentally. The model of the slipper system has been established by original neural network (NN) method.

Findings

First, the effects of the slipper geometry with smooth and conical sliding surfaces on the slipper performance were experimentally analyzed. Smooth sliding surface slippers showed a better performance then the conical surface ones. According to the results, the neural predictor would be used as a predictor for possible experimental applications on modeling this type of system.

Originality/value

This paper discusses a new modeling scheme known as artificial NNs an experimental and a NN approach have been employed for analyzing axial piston pumps. The simulation results suggest that the neural predictor would be used as a predictor for possible experimental applications on modeling bearing system.

Details

Industrial Lubrication and Tribology, vol. 61 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

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Article

Erdem Koç and Emel Ceyhun Sabir

The main purpose of the research work carried out is to investigate the hydraulic balance conditions of the sealing ring of a mechanical radial face seal in terms of the…

Abstract

Purpose

The main purpose of the research work carried out is to investigate the hydraulic balance conditions of the sealing ring of a mechanical radial face seal in terms of the residual load acting on the ring by employing the theoretical model developed mentioned in the first part of the investigation.

Design/methodology/approach

The end load balance conditions for the movable seal ring have been examined by considering the residual load acting on the ring under all running conditions. The main lubrication and sealing mechanism is assumed to be due to the existence of the relative tilt between the mating surfaces, which is formed by the bearing misalignment. The aim of the theoretical model developed is to predict the necessary minimum film thickness between the relatively moving surfaces by considering the non‐dimensional running (operating) conditions and the geometrical parameters defined. The theoretical model is based on the main differential equation (Reynolds' equation) which is achieved by adopting the standard finite difference form.

Findings

Under the combination of the hydrostatic clamping forces and hydrodynamic restoring forces, an equilibrium position is reached with the seal ring displaced from its central position. At a particular non‐dimensional pressure, the seal ring comes into contact with the stationary plate and this limits the upper value of pressure that can be resisted by the mechanical seal type examined without metal‐metal contact. With the theoretical model developed, it was found that the minimum film thickness between the realtively moving surfaces could be predicted.

Originality/value

This paper provides a considerable scientific contribution to the field of lubrication and sealing aspect of the mechanical radial face seals. The results presented in the first part of the investigation and the remarks outlined in this paper would be considered as a design tool for the seal designers with special reference to ring behaviour under hydrodynamic and hydrostatic conditions.

Details

Industrial Lubrication and Tribology, vol. 59 no. 4
Type: Research Article
ISSN: 0036-8792

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Article

Erdem Koç and Oğuz Demiryürek

The purpose of this paper is to investigate the hydrodynamic performance of a single‐screw extruder with special reference to metering region.

Abstract

Purpose

The purpose of this paper is to investigate the hydrodynamic performance of a single‐screw extruder with special reference to metering region.

Design/methodology/approach

The hydrodynamic analysis of a single screw extruder is carried out by dimensional and non‐dimensional parameters defining the polymer flow behaviour. The flow types formed in the extruder channel are defined and the relationship between the flow with the extruder geometry is examined.

Findings

The theoretical model developed is capable of estimating the hydrodynamic behaviour of extruder metering region. With the model developed, extruder geometry and polymer flow rate under different operating conditions can be predicted.

Originality/value

This paper offers a quick and easy opportunity to examine the hydrodynamic behaviour of extruder metering region. With the theoretical model developed, the behaviour of the flow in extruder can be modelled and estimated.

Details

Industrial Lubrication and Tribology, vol. 61 no. 4
Type: Research Article
ISSN: 0036-8792

Keywords

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Article

Oğuz Demiryürek and Erdem Koç

The purpose of this paper is to investigate the design dimensions in pressure or metering region of a single‐screw extruder by determining viscous power loss. The paper is…

Abstract

Purpose

The purpose of this paper is to investigate the design dimensions in pressure or metering region of a single‐screw extruder by determining viscous power loss. The paper is the second part of a series.

Design/methodology/approach

Viscous power loss formed in the extruder screw channel and the radial clearance is determined and evaluated in terms of non‐dimensional parameters in order to obtain a theoretical model.

Findings

The theoretical model developed is capable of estimating the viscous power loss in the extruder metering region. With the model developed, extruder geometry and viscous power loss under different operating conditions can be predicted.

Originality/value

This paper offers a quick and easy opportunity to examine the viscous power loss in the extruder.

Details

Industrial Lubrication and Tribology, vol. 61 no. 4
Type: Research Article
ISSN: 0036-8792

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Article

Fabián Castaño and Nubia Velasco

To solve the problem, a mathematical model is proposed; it relies on a directed acyclic graph (DAG), in which arcs are used to indicate whether a pair of appointments can…

Abstract

Purpose

To solve the problem, a mathematical model is proposed; it relies on a directed acyclic graph (DAG), in which arcs are used to indicate whether a pair of appointments can be assigned to the same route or not (and so to the same care worker). The proposed model aims at minimizing the personnel required to meet daily demand and balancing workloads among the workers while considering the varying traffic patterns derived from traffic congestion.

Design/methodology/approach

This paper aims at providing solution approaches for addressing the problem of assigning care workers to deliver home health-care (HHC) services, demanding different skills each. First, a capacity planning problem is considered, where it is necessary to define the number of workers required to satisfy patients' requests and then, patients are assigned to the care workers along with the sequence followed to visit them, thus solving a scheduling problem. The benefits obtained by permitting patients to propose multiple time slots where they can be served are also explored.

Findings

The results indicate that the problem can be efficiently solved for medium-sized instances, that is, up to 100 daily patient requests. It is also indicated that asking patients to propose several moments when they can receive services helps to minimize the need for care workers through more efficient route allocations without affecting significantly the balance of the workloads.

Originality/value

This article provides a new framework for modeling and solving a HHC routing problem with multiskilled personnel. The proposed model can be used to identify efficient daily plans and can handle realistic characteristics such as time-dependent travel times or be extended to other real-life applications such as maintenance scheduling problems.

Details

The International Journal of Logistics Management , vol. 32 no. 1
Type: Research Article
ISSN: 0957-4093

Keywords

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Abstract

Details

Marketing Management in Turkey
Type: Book
ISBN: 978-1-78714-558-0

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Article

Shaikh Asad Ali Dilawary, Amir Motallebzadeh, Muhammad Afzal, Erdem Atar and Huseyin Cimenoglu

The purpose of the study is to examine the sliding wear performance of plasma transfer arc (PTA) deposited and laser surface melted (LSM) Mo modified Stellite 12…

Abstract

Purpose

The purpose of the study is to examine the sliding wear performance of plasma transfer arc (PTA) deposited and laser surface melted (LSM) Mo modified Stellite 12 hardfacings under high contact stresses (i.e. >20 GPa).

Design/methodology/approach

For this purpose, after structural characterization, sliding wear tests have been conducted using sphero-conical diamond indenter as the counterface with different normal loads. The wear tracks formed on the hardfacings were examined by atomic force microscopy and scanning electron microscopy.

Findings

Both hardfacings showed severe wear (at high contact stress levels ranging from 24 to 41 GPa), which progressed by plastic deformation, although the wear resistance of LSMed hardfacings was better than the PTA hardfacings by a factor of two due to its near surface microstructure characterized as carbide-rich zone.

Originality/value

Sliding wear characterization of a promising 10 Wt.% Mo modified version of commercial Stellite 12 hardfacings (as reported previously by authors) was done in as PTA and LSMed states using nanomechanical test system. To the best of authors’ knowledge, no report is available in the open literature on such hardfacings under these testing conditions.

Details

Industrial Lubrication and Tribology, vol. 72 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

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