Types Of Sliders Research Articles

Investigation of Effects of Slider Structure on the Reversing Performance of Four-Way Reversing Valve

Unsmooth reversing is one of the most common faults in the four-way reversing valve of the air conditioning system, and the airflow in the valve chamber and the shape of the slider of the reversing valve are the main factors in unsmooth reversing. In order to study the influence of the airflow in the chamber and the slider shape on the reversing process, the fluid flow in the valve chamber of a four-way reversing valve is obtained using computational fluid dynamics (CFD) simulations, and the influence of the slider structure on slider thrust and resistance of the four-way reversing valve is analyzed. Four-way reversing valves with no-cutting, straight-cutting and arc-cutting sliders are employed to evaluate the reversing characteristics. A pressure measuring device for a four-way reversing valve chamber is designed, which is performed to test the chamber pressure of three different types of sliders of four-way reversing valves. The maximum error of experimental tests and simulations is within 5% of engineering tolerance, so as to verify the reliability of numerical simulation. The resistance-to-thrust ratio of the slider is raised to evaluate the performance of the reversing, which can guide the design of the valve and slider. The results indicate that the chamber pressure and resistance-thrust ratio with the cutting slider are reduced, which is beneficial to the reversing of the four-way reversing valve. Compared with the straight-cutting structure, the arc-cutting slider four-way reversing valve has a more stable reversing process and better comprehensive reversing performance. Results demonstrate that both the straight-cutting structure and arc-cutting structure of the slider can improve the process performance but the arc-cutting slider is better.

Seismic behavior of LRB and FPS type isolators considering torsional effects

This study aims to investigate seismic behavior of lead-core rubber elastomeric bearing (LRB) and curved surface friction pendulum slider (FPS) base isolated models considering torsional irregularity for typical reinforced concrete buildings. Nonlinear behavior of structural members was considered in analysis models. Total of 1408 different nonlinear time history analyses of 3-dimensional 3, 5, 7 and 9-story models were performed considering 11 spectrum compatible ground motion record pairs. The results indicate that when the rigidity center of base isolator system is not coincided with mass center of superstructure, highest torsional irregularity coefficients were calculated. Lead-core rubber elastomeric bearing type isolators are more sensitive to torsional effects compared to curved surface friction pendulum slider type isolators. Torsional irregularity coefficient values of lead-core rubber elastomeric bearing models with 20% eccentricity are 47% higher than models without eccentricity in terms of averages. The obtained results indicate that significant scatter exists in displacement values of individual ground motion records for all models. Using limited number of ground motion records may lead to inaccurate predictions of seismic demands.

Friction and wear properties of nanostripe-inducing structures in vacuum environment

We examined the friction and wear properties of nanostripe-inducing structures (NISs), namely, a multilayer film consisting of layers of a soft metal (Ag) and a hard metal (Cr) applied on a periodic slope array on a Si substrate. The friction coefficients of the different samples of the Cr-Ag NISs were measured by rubbing four different types of sliders against the samples using a reciprocating friction tester under dry conditions. The wear depths were examined using a confocal microscope. It was found that, when the rubbing was done under vacuum conditions of 2 × 10−4 Pa, the friction coefficient decreased with increasing number of oscillations, and its values ranged between 0.2 and 0.3 at the end of the test. In addition, the wear resistances of the different NIS samples were observed to be one order of magnitude higher than that of a single Cr layer on a periodic slope array.

Interactive Smart Fashion Using User-Oriented Visible Light Communication: The Case of Modular Strapped Cuffs and Zipper Slider Types

Because LEDs offer flexible expressions such as brightness, color control, and various patterns, they are popularly used in multidevice interactions. Moreover, LEDs have excellent physical characteristics. However, existing LED light-based wearable interactions are designed for interest and attention. So, LED can be used in fashion as it can give new look to our style and at the same time also as an interaction device. Therefore, in this paper, we present the design guideline for regulating the technical implementation, design strategies, and directions of interactive LED devices. The technology and design concepts are demonstrated through a case study (analysis) of an existing LED light-based wearable interaction. We also design a scenario-based iterative collaborative design process model. Finally, we develop a smart fashion of modular strapped cuffs and zipper slider types that can be attached and detached according to the user’s preference as the interactive smart fashion using user-oriented visible light communication, ultimately pursuing a visual-MIMO (Multiple-Input Multiple-Output) product through stepwise strategy.

Repeatable and Non-repeatable FH Modulation Study Near Head Contact

The lower head–media spacing (HMS) is always expected for achieving better recoding performance at high linear density. Besides the efforts to reduce the overcoat thickness of head and media, the low flying height (FH) and smaller FH modulation (FHM) are necessary to ensure the low HMS and good interface reliability. In the current HDD, the FH change is measured from the readback signal by the Wallace spacing loss equation. The real-time dynamic FH signals consist of repeatable and non-repeatable FH changes, or FHM. The repeatable FHM (RFHM) correlates with the disk morphology variations. It usually has the variation of transition parameter $a$ inside. Because the change of $a$ is the noise of the RFHM, it has to be very careful for the compensation of the RFHM by thermal FH control. Otherwise, it may cause unexpected head–disk contact. The non-RFHM (NRFHM) measurement is able to remove the media-related noise, which has a good testing accuracy of around 1 A. This paper studies both RFHM and NRFHM characteristics of four types of sliders with different air-bearing surface designs.

Die wear in stamping of advanced high strength steels – Investigations on the effects of substrate material and hard-coatings

This study intended to investigate the wear performance of different coatings (two different PVD, a CVD, and a TD coating) applied onto variety of substrate materials (DC 53, SKD 11, DRM 3, DRM 51) against AHSS sheet blanks. A non-reciprocating, CNC-based, slider type of tester was employed in wear tests. In effect of coating study, it was found that TD coated samples performed slightly better than the other samples. The substrate material effect study, on the other hand, revealed that the TD coated DRM 3 and DRM 51 die samples attained the lowest specific wear rate.

水平スライド式舶用動揺安定システムの開発 －制御システムと応用

水平スライド式舶用動揺安定システムの開発 －制御システムと応用

Pseudo-Nine-Point Finite Difference Method for Numerical Analysis of Lubrication

Contours of surface texture of contact faces are not always parallel to the directions of the axis in solving Reynolds equations with finite difference method, and this often induces significant pressure saw-tooth effect, which results in an unignored analysis error. In this paper, pseudo-nine-point finite difference, as a new finite difference method, is introduced to solve the lubrication numerical problem of pressure saw-tooth. Also, application is carried out in gas lubrication of hard disk systems to verify the validity of the new method. In analysis, pressure distributions and gas floating forces are calculated for two different types of sliders, and the astringency and efficiency of the new method is discussed. Numerical results show that the pseudo-nine-point finite difference method can restrain pressure saw-tooth evidently, and presents better astringency and efficiency than the traditional five-point finite difference method. With the increase in mesh density, pressure distribution and gas floating force trend to steady. Also, numerical values of the floating force agree well with the experimental ones.

Wear performance assessment of alternative stamping die materials utilizing a novel test system

Stamping of Ultra/Advanced High Strength Steel (U/AHSS) sheets leads to high contact stresses and non-uniform strains. These, in turn, cause high wear rates and springback. In order to prevent the excessive wear effect in stamping dies, various countermeasures have been proposed such as alternative coatings, modified surface enhancements in addition to the use of newer die materials including cast, cold work tool, and powder metallurgical tool steels. A new slider type of test system was developed to replicate the actual stamping conditions including the contact pressure state, sliding velocity level and continuous and fresh contact pairs (blank-die surfaces). A vertical machining centre, with vertical and normal force sensors mounted on its spindle, was employed to generate the contact pressure and controlled movement of die samples on sheet blank. Several alternative die materials in coated or uncoated conditions were tested against different AHSS and stainless steel blanks under certain load, sliding velocity, lubrication circumstances. This paper briefly describes the test system and experimental methodology, and presents the results for wear resistance performance of an air-hardening cold-work tool steel sample with different coatings tested against DP 600 AHSS grade sheet blanks.

Fluorine-ion-implanted air-bearing surface for low-friction head–disk interface

With the aim of reducing the lubricant–slider interaction by reducing slider surface energy, we fabricated several types of sliders with fluorine-ion-implanted (FII) air-bearing surfaces by using different levels of acceleration voltage for FII. With a low acceleration voltage, the fluorine-ions tended to be concentrated at shallower depths from the slider surface, and the contact angle of the water droplets was greater. The FII-treated slider showed lower touch-down height, which implies an improvement of slider stability at near-contact regime. The polar force component of the surface energy of FII-treated slider surface showed a good correlation with a thermally flying-height control heater power at touch-down. It is estimated that FII-treatment can reduce the polar force component of the surface energy and reduce the slider-lubricant interaction, resulting in a reduction of slider touch-down height.

水平スライド式舶用動揺安定システムの開発-水平スライド式動揺安定システムの運動解析と性能分析

水平スライド式舶用動揺安定システムの開発-水平スライド式動揺安定システムの運動解析と性能分析

Active Vibration Control of a Micro-Actuator for Hard Disk Drives using Self-Sensing Actuator

In this article, active vibration control of a micro-actuator for hard disk drives using self-sensing actuation is presented. The micro-actuators used in this article are a slider type and a suspension type. The self-sensing performance of the installing position is compared and evaluated. An assembly including these micro-actuators may not be able to sense some vibration of suspension modes. Feedback control results of direct velocity feedback and positive position feedback are presented. The feasibility of these self-sensing approaches as a vibration suppression control on the micro-actuator was verified. Using the slider type micro-actuator, the sway mode spike signal in power spectrum density was suppressed by 76% using the direct velocity feedback control, and by 60% using the positive position feedback control. Using the suspension type micro-actuator, the suspension second bending mode spike signal in power spectrum density was reduced by 74% using the direct velocity feedback control, and by 96% using the positive position feedback control. The control scheme using self-sensing signals can partially dampen the suspension modes.

Minimizing errors during in vitro testing of multisegmental spine specimens: Considerations for component selection and kinematic measurement

Apparatus-induced artifacts may invalidate standard spine testing protocols. Kinematic measurements may be compromised by the configuration of motion capture equipment. This study has determined: (1) the influence of machine design (component friction) on in vitro spinal kinetics; (2) the sensitivity of kinematic measurements to variations in the placement of motion capture markers. A spinal loading simulator has been developed to dynamically apply pure bending moments (three axes) with or without a simultaneous compressive preload. Two linear slider types with different friction coefficients, one with caged ball bearings and one with high-precision roller bearings on rails, were mounted and specimen response compared in sequential tests. Three different optoelectronic marker cluster configurations were mounted on the specimen and motion data was captured simultaneously from all clusters during testing. A polymer tube with a uniform bending stiffness approximately equivalent to a polysegmental lumbar spine specimen was selected to allow reproducible behavior over multiple tests. The selection of sliders for linear degrees of freedom had a marked influence on parasitic shear forces. Higher shear forces were recorded with the caged-bearing design than with the high-precision rollers and consequently a higher moment was required to achieve a given rotation. Kinematic accuracy varied with each marker configuration, but in general higher accuracy was achieved with larger marker spacings and situations where markers moved predominantly parallel to the camera's imaging plane. Relatively common alternatives in the mechanical components used in an apparatus for in vitro spine testing can have a significant influence on the measured kinematic and kinetics. Low-magnitude parasitic shear forces due to friction in sliders induces a linearly increasing moment along the length of the specimen, precluding the ideal of pure moment application. This effect is compounded in polysegmental specimens. Kinematic measurements are highly sensitive to marker design and placement, despite equivalent absolute precision of individual marker measurements, however marker configurations can be designed to minimize errors related to spatial distribution and system bias.

Design of swing arm type actuator and suspension for micro optical disk drive

One of the trends on information storage device is focused on the development of micro-optical devices with optical flying head (OFH). Many different types of sliders for OFH and optical component systems have been introduced in the literature. However, the important issues on the mechanical system, which consists of suspension, swing arm and voice coil motor (VCM) part has not been discussed up to date. In this research, a swing arm type actuator with suspension for micro optical disk drive is designed and developed, basically focused on the mechanical issues, which should be solved for real application.

An adaptive finite element strategy for analysis of air lubrication in the headdisk interface of a hard disk drive

In this paper a finite element solution of the modified Reynolds equation using isoparametric, bilinear quadrilateral elements with an adaptive meshing strategy is presented. The modified hydrodynamic stiffness method (Smith, 1995) was used to obtain a coupled solution of the air bearing equation with the slider equilibrium equations. The vertex label based adaptive meshing algorithm of Cheng et al. (1999) was also implemented. The problem is initially solved with a regular quadrilateral FE mesh. The mesh adaptation (hrefinement) is based on the relative pressure gradients in the initial solution, and on the geometry of the slider. The refinement is implemented on an existing element, if preset criteria on the pressure gradient and/or slider geometry are exceeded. The method is described in detail. Examples are presented. Two types of sliders have been used, namely the 50% taper flat slider, and the negative air bearing slider.

Slider design for sub-3-nm flying height head–disk systems

It is important to further push slider's gap flying height from the current value of 7–8nm in mass production to 2.5–3nm, in order to increase the areal density of magnetic data storage technology from the current 60–80Gb/in2 in mass production to 1Tb/in2. Furthermore, perpendicular magnetic recording will be the only choice for area densities beyond 300Gb/in2, though it might be more sensitive to the fluctuation of the flying height and needs higher flying height stability. This paper reports the authors’ efforts in both reducing slider's gap flying height and increasing the stability of the flying height. Analysis suggests that heat energy generation in both reading and writing operations affects the stability of the flying height, in addition to the intermolecular forces and the flying height modulations caused by disk waviness. An important design strategy is to have high air pressure and pressure gradient around the read/write element. Results suggest that introducing a sub-shallow step in slider's trailing part is an effective approach of achieving high air pressure and pressure gradient. A new type of slider is designed accordingly. Aerodynamic performance analysis indicates that the proposed slider can fly stably at a flying height below 3nm.

Investigation of disk damage caused during load/unload using a surface reflectance analyzer

Wear of the carbon layer of a magnetic recording disk is investigated during load/unload using a surface reflectance analyzer (SRA). Wear is determined as a function of the number of the load/unload (L/UL) cycles, the vertical head speed, the disk rotational speed, and the air bearing design. Two types of subambient pressure sliders are used in the experiments, the difference between the two designs being related to the size and position of the subambient pressure region. The load/unload behavior of the two slider types is determined numerically using a finite element air bearing simulator.

Design and Analysis of a Suspension for OFH In Small Form Factor ODD

One of the trends on information storage device is focused on the development of small form factor optical disk drives with Optical Flying Head (OFH). Many different types of sliders for OFH and optical component systems have been introduced in the literature. However, the research about the actuating system is not much in the literature. In order for a slider with OFH to be successfully implemented in the system, a suspension is needed to be properly designed. Generally, a suspension supports slider performance, and tracking servo capacity in HDD. As the suspension supported the OFH slider which has larger mass and objective lens, it is required to satisfy shock performances for the mobility, and it also should meet the optical characteristics. In this study, the suspension for small form factor ODD is designed with sensitivity analysis. The dynamic characteristics of the suspension with OFH are analyzed finite element method and experiment, and the flying height and its variation of the OFH slider is measured by laser doppler vibrometer.

Effects of Air Bearing Stiffness on a Hard Disk Drive Subject to Shock and Vibration

A finite element model of a hard disk drive (HDD) is developed to investigate the transient response of an operational HDD subject to shock and vibration. The air bearing stiffness of the head disk interface is determined from a finite element solution of the Reynolds equation and approximated with linear springs. The structural response is analyzed for several types of sliders with a wide range of air bearing stiffness. Results show the response of the head-disk interface subject to shock and the modes excited by vertical and lateral vibrations of the HDD.

Analysis of Tracking Characteristics and Optimum Design of Tri-Pad Slider to Micro-Waviness

This paper describes optimum air-bearing design of a tri-pad slider in terms of tracking ability to micro-waviness based on theoretical analysis of the two-degree-of-freedom slider model and the distributed and concentrated air-bearing stiffness model. Although a short tri-pad type slider was introduced through the load/unload technique, we point out that this type of slider is superior to the traditional rail type slider in terms of tracking ability to micro-waviness. More importantly, the distance between head-gap position and the rear air-bearing center should be made as small as possible. The spacing variation due to lower mode resonance can be eliminated if the positions of front and rear air-bearing centers are located at the center of percussion. The resonance amplitude of the higher order mode in spacing variation can be reduced if the length of the rear air-bearing pad is designed to be 1.2∼1.3 times the wavelength of the higher mode resonance frequency. Since the momental stiffness of the front air-bearing prevents the head-gap from tracking micro-waviness, the front air-bearing length should be made short or the ratio of rear to front air-bearing stiffness should be made large. If the resonance amplitude of the lower mode must be decreased, the front air-bearing length should be designed to be 1.2∼1.3 times the wavelength of the lower mode resonance frequency.