Plunger Motion Research Articles

Impact on force decrease at the end of actuator plunger motion

Impact on force decrease at the end of actuator plunger motion It is shown that decrease and damping of the traction force at the end of the plunger move is possible not only due to application of a special keeper design, but also due to change of the plunger shank geometric form. The computer modeling with the use of finite element method is used to analyze the influence of system geometry on force distribution along plunger movement. The damping effect is confirmed when special shape plunger shanks are used.

Numerical Simulation and analysis of molten flow in the shot sleeve of die casting process

AbstractThis work presents a numerical study of the flow of molten metal in the shot sleeve of horizontal high‐pressure die casting machine during the injection process. The analysis of the wave of the molten metal created by plunger motion can be of help in reducing porosity in manufactured parts caused by air entrapment. The used numerical model, which considers the problem as two‐dimensional, is based on the conservation equations of mass and momentum. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Rapid Transport of Water via a Carbon Nanotube Syringe

The controlled flow of water molecules at the nanoscale is an initial step to many fluidic processes in nanotechnology. Here we show how thin films of water can be drawn through a nanosyringe built from a carbon nanotube membrane and a “plunger”. By increasing the speed of withdrawal of the plunger, we can obtain molecular transport through the membrane at flux rates exceeding 1025 molecules cm−2 s−1. Above a threshold speed around 0.25 nm/ns (25 cm/s), molecules cannot fill the chamber created by the plunger motion as fast as the chamber expands, and the resulting flux rate drops. By considering hydrophobic or hydrophilic plungers, we unexpectedly find that the nature of the water-plunger interactions does not affect the flux rate or the threshold plunger speed. While the water structure near the plunger surface differs significantly for different plunger interactions, the failure of the film away from the plunger surface is responsible for loss of transport. As a result, the surface interactions play a limited role in controlling the flux.

Combdrive Configuration for an Electromagnetic Reluctance Actuator

This paper presents a novel combdrive configuration of a linear magnetic microactuator. We discuss in detail the influence of the air-gap geometry on the plunger motion and give design rules to avoid pull-in behavior. This analysis results in a new configuration, which is, so far, only known for electrostatic actuators. The magnetic flux is guided over several interdigitating comb structures with moderate large gap width of 25 mum instead of one single plunger, as reported for earlier designs. This results in larger forces, scaling with the number of comb fingers, until the material reaches saturation. The new configuration linearizes the characteristics and saves driving power without sacrificing fabrication stability, which would arise from small air-gap widths. Several combdrive actuators featuring one, two, and eight comb fingers were fabricated in LIGA technology, simulated, and tested. For a driving current of 40 mA, the achievable stroke is measured to increase by 800% for eight comb fingers in comparison to one finger. Alternatively, for a given stroke, a reduction of the driving current of more than 50% is measured.

Optimization of an electromagnetic comb drive actuator

We present the first electromagnetic comb drive actuator which allows for over 100 μm of linear actuator motion at large air gap widths of 25 μm at 300 coil windings, a structural height of 400 μm and for an applied current of 8 mA. Previously reported designs require very narrow air gaps of 3 μm at structural heights of up to 1 mm [K. Fischer, H. Guckel, Long throw linear magnetic actuators stackable to one millimeter of structural height, Microsyst. Technol., 4 (1998) 180–183] which makes them sensitive to operate, and challenging to fabricate. The new design reduces the reluctance by a parallel connection and cascading of several pole shoes as is well known for electrostatic actuators. This reduces the current consumption and linearizes the current–displacement characteristic. The cascaded design further enhances the displacement range at the cost of a slightly increased current consumption at the onset of the stroke. To analyze the influence of the number of air gaps on the plunger motion the total cross-sectional area of the magnetic core is kept constant while the number of air gaps is varied. Magnetic and mechanical material properties are measured for an accurate simulation of the system behavior. Experimental results confirm the theoretical predictions.

A simple method for automotive switching-type solenoid valve stuck fault detection

This paper proposes a method for the diagnosis of faults in switching-type solenoid valves widely used in automotives, specifically the case in which the valve plunger is sticking during operations. This kind of fault is frequently encountered in electro-hydraulic systems of in-use vehicles and is difficult to detect because the solenoid valves are generally inside the system. A Kalman filter-based fault detection algorithm is derived. Experimental results showed that, using only the measured voltage across and current through the coil of the solenoid, the designed algorithm predicted the plunger motion and diagnosed the stuck fault accurately.

Flavor Release of Diacetyl and 2-Heptanone from Skimmed and Full Fat Milk under Mouth Conditions

To gain insight into the process of retronasal olfaction, flavor release from skimmed milk and full fat milk (containing 3.75% fat) was investigated using a model mouth system with a screw plunger. Large differences were determined in the quantity of flavor released using two different methods : with screw plunger movement, which represents “retronasal” flavor release, and without the screw plunger, which represents “orthonasal” flavor release. The screw plunger motion accelerated the release of diacetyl and 2-heptanone in both skimmed and full fat milk. The amount of diacetyl released was not influenced by the fat content of the milk in either case (with or without screw plunger operation), while the amount of 2-heptanone released was lower in full fat milk both with and without screw plunger motion. The influence of fat content on the amount of flavor released was explained by the lipophilicity of the flavor components, and mass transfer also contributed to release of the hydrophilic flavor compound.

On the Critical Plunger Speed and Three-Dimensional Effects in High-Pressure Die Casting Injection Chambers

During the initial slow stage of the injection process in high-pressure die casting machines with horizontal cold chamber, a plunger pushes the molten metal which partially fills the injection chamber, causing the formation of a gravity wave. The evolution of the wave surface profile, which depends on the plunger acceleration law, may trap air in the molten metal, causing porosity when the metal solidifies. In this work, a one-dimensional shallow-water model, which is solved numerically using the method of characteristics, and a three-dimensional numerical model, based on a finite element formulation and the volume of fluid (VOF) method for treating the free surface, are used to analyze the flow of molten metal in an injection chamber of circular cross section. The results for the evolution of the free surface obtained from both models for different plunger motion laws and initial filling fractions of the injection chamber were in good agreement for broad ranges of operating conditions. The existence of a critical plunger speed, above which the reflection of the wave of molten metal against the chamber ceiling might appreciably increase air entrapment effects, is investigated. The results for the wave profiles in chambers of circular cross section are compared with those obtained in an equivalent two-dimensional configuration of the injection chamber, for which the shallow-water model is solved analytically. It is shown how the results obtained by applying the one-dimensional model to a two-dimensional chamber configuration can be used to reproduce, with an acceptable degree of accuracy, the salient characteristics of the flow of molten metal in a real injection chamber of circular cross section.

Analysis of the Flow in a High-Pressure Die Casting Injection Chamber

The flow in the injection chamber of pressure die casting machines is analyzed using a model based on the shallow-water approximation which takes into account the effects of wave reflection against the end wall of the chamber. The governing equations are solved numerically using the method of characteristics and a finite difference grid based on the inverse marching method. The results of the model for wave profiles, volume of air remaining in the injection chamber at the instant at which the molten metal reaches the gate to the die cavity, and optimum values of the parameters characterizing the law of plunger motion, are compared with the numerical results obtained from a finite element code, which solves the two-dimensional momentum and mass conservation equations, taking into account nonhydrostatic and viscous effects. We found that, although the shallow-water model does not provide a very accurate estimation of the mass of entrapped air in the injection chamber for certain ranges of working conditions, it does describe reasonably well the influence of the acceleration parameters and the initial filling fraction on the entrapped air mass, and can be of help in selecting operating conditions that reduce air entrapment while keeping the injection chamber filling time as low as possible.

Features of solid-phase extrusion of polymers. Polypropylene

Features of the solid phase extrusion of amorphous-crystalline polymers have been investigated for polypropylene and polytetrafluoroethylene. Extrusion without defects is feasible only within a certain area of change in the extrusion temperature and in the rate of plunger motion; here the extrusion pressure, which is one of the major characteristics of the process, remains constant. A mathematical model is proposed whereby extrusion pressures may be predicted within a wide range of temperature and rates of plunger motion based on uniaxial drawing experiments. The character of the experimental curves is accounted for in terms of the proposed model.

Computer-Aided Design of a Punch Assembly

In the high-speed page printing systems used as peripherals to computers, the paper moves at a speed of around 30 in./s. The printing and punching of the paper has to be done when the paper is in motion. If the punching is not finished in a short enough time, the paper would get torn up by the punchette. In a typical punch assembly as used in modern page printing systems, a plunger is driven forward by the force of a solenoid. Plunger impacts the punchette which in turn punches a hole in the paper which is in motion. To minimize the flight time of the punchette with the object of increasing paper speed, the design parameters of the punch assembly must be carefully selected. In this paper, a model for the punch assembly is developed. The necessary equations for plunger and punchette motion are derived. The design parameters, such as the masses of the plunger and punchette, constants for springs used in the assembly, force generated by the solenoid, and the gap between the plunger and punchette, are varied using a Rosenbrock algorithm to minimize the flight time of the punchette. The results obtained indicate that by the use of a Computer-Aided Design approach optimal values of design parameters can be found before the development of prototypes and experiments.

A Dynamic and Static Analysis of a Solenoid Actuated Stepping Motor

When the law of conservation of energy is applied to a solenoid actuated stepping motor, it becomes possible to derive an expression for the maximum stepping rate and to explain the phenomenon of skipping. If a sinusoidal electric input and a simple harmonic motion for the plunger are assumed as a mathematical model, the phenomenon of overspin can be explained as a consequence of resonance between the electric input and the plunger motion.

A New Selsyn Interlock Selection System<!--<xref ref-type="other" rid="fn1-10.5594_J12748">*</xref>-->

This paper describes a new type of Selsyn interlock selector switch wherein six-pole, five-position rotary switches utilize a combination operating motion. Position selection is obtained by rotary motion and contacting by plunger motion.

An Investigation of Experimental Methods of Determining Sucker-rod Loads

The problem of determining the most desirable operating conditions of anoil-well pumping unit, the selection of the proper material and size of suckerrods, and the design of the pumping unit, requires that the sucker-rod loads beknown with a reasonable degree of accuracy. In production practice, it is alsodesirable to know the effects of operating speeds and strokes on a plungermotion, as well as on the rod loads. For a particular well, data on rod loads can be obtained by measuring the loadin sucker rods with a dynamometer. This method is not satisfactory because itdoes not permit the various factors to be investigated independently. It isalso impossible to measure the plunger motion simultaneously with rod motionunder operating conditions. The mathematical solution is impractical because ofthe simplifications that have to be made to get a solution and the tremendousamount of numerical work that is necessary after such a simplified solution hasbeen attained. This paper shows how analogies and models can be applied to thesolution of these problems. The loads set up in a sucker-rod string during the ordinary pumping cycle aremade up of the weight of the rods, force required to accelerate the rods, weight of the oil and force required to accelerate the oil on the upstroke, rodfriction, stuffing-box friction, plunger friction, friction of the oil in thetubing and rods, and friction loss through the valves. The problem ofdetermining the sucker-rod load is further complicated by the fact that thelong oil column and the sucker-rod column act as springs, which affect thetransmission of the polished-rod motion. A further complication is the factthat the motion cannot be transmitted at a speed greater than that of thevelocity of sound in the material, and this means that there will be a time lagin the transmission in the motion, as well as a modification of its magnitudeand a phase displacement.