Feed Path Research Articles

Outwards and inwards crimping of tube ends by single-point incremental forming

Abstract Tube end forming is a frequently used approach in the production of tubular parts. Traditional tube end forming is conducted on press with dedicated punch and die. The current study examined a new method for crimping open tube ends based on the single-point incremental sheet forming technology. Al 6061 tubes with outer diameter of 38 mm and thickness of 1.0 mm were employed in the study. The results proved that outwards/inwards crimping of open tube ends can be accomplished utilizing this flexible method. Tube wall deformations are dominated by the combination of processing parameters, especially the feeding path and tool geometry. Compared with the integer formation of press working, though incremental tube end crimping has smaller axial load during forming, instability phenomena of the wall are prone to take place due to the localized and asymmetrical action of the tool, and the absence of die constraint as well.

A Fundamental Investigation of Modulated Tool Path Turning Mechanics

This paper describes an experimental machining platform that provides metrology during tube turning (orthogonal cutting) for force, global temperature, feed motion, tool wear, and chip formation during continuous feed and modulated tool path, or MTP, turning. MTP is a technique which produces discontinuous chips by superimposing tool oscillations in the tool feed direction on the nominal feed rate to repeatedly interrupt the cutting process. AISI 1026 cold-drawn steel machining experiments are performed and data is presented for: 1) feed motion and modeling; 2) force measurement and modeling; 3) temperature measurement; and 4) chip formation for constant and MTP tool paths. Shear-localized chip formation that begins and ends during a single MTP chip is demonstrated.

A Healer Reinforcement Approach to Self-Healing in Smart Grid by PHEVs Parking Lot Allocation

Self-healing is one of the essential properties of smart grid. Improving the self-healing capability of the smart grid is referred to as healer reinforcement. In this paper, a new healer reinforcement approach is introduced, contributing PHEVs, through optimal parking lot (PL) placement and sizing, under contingencies, by considering the available control and protective devices. Moreover, the PL placement and sizing problem formulation is extended by considering PHEVs participation as both backup and storage units in the self-healing process. PHEVs contribution as backup units could provide electricity for faulted zone customers. Furthermore, demand variations during the restoration might lead to congestion occurrence in the backup feeder. Hence, the PHEVs contribution as storage units could prevent congestion occurrence and enable execution of the best restoration strategy, through charging in light load and injecting power to the backup feeding path in the peak load of repair time. In addition, the stochastic nature of PHEV owners' behavior is modeled in service restoration and the possibility of reactive power injection by PLs is considered in the service restoration process. The proposed formulation is applied to a standard test system (RBTS-4) to minimize a combined effect of the customer-based (SAIDI) and cost-based (TCR) reliability indices. The simulation is conducted to investigate the effects of physical limitations on candidate locations as well as PHEVs participation as both backup and storage units. Two sensitivity analyses are conducted on the objective function weighting coefficient and the total number of required charging stations to evaluate the effect of optimization parameters on final PL locations and sizes.

Shocks and angular momentum flips: a different path to feeding the nuclear regions of merging galaxies

We study the dynamics of galaxy mergers, with emphasis on the gas feeding of nuclear regions, using a suite of hydrodynamical simulations of galaxy encounters. The high spatial and temporal resolution of the simulations allows us to not only recover the standard picture of tidal-torque induced inflows, but also to detail another, important feeding path produced by ram pressure. The induced shocks effectively decouple the dynamics of the gas from that of the stars, greatly enhancing the loss of gas angular momentum and leading to increased central inflows. The ram-pressure shocks also cause, in many cases, the entire galactic gas disc of the smaller galaxy to abruptly change its direction of rotation, causing a complete "flip" and, several $10^8$ yr later, a subsequent "counter-flip". This phenomenon results in the existence of long-lived decoupled gas-stellar and stellar-stellar discs, which could hint at a new explanation for the origin of some of the observed kinematically decoupled cores/counter-rotating discs. Lastly, we speculate, in the case of non-coplanar mergers, on the possible existence of a new class of remnant systems similar to some of the observed X-shaped radio galaxies.

Feed paths and hot spots computation based on a time gradient method in casting

The aim of the present work is to calculate feed paths and hot spots by the time gradient method, which is based on the fact that the fastest solidification direction is the direction of temperature gradient. The energy conservation equation was solved coupling with N-S equation. The temperature field calculated under the circumstance of taking fluid flow into consideration has been compared with the experiment results in a step casting. Feed path is computed by tracking the direction of the time gradient in each calculation during the solidification process. Effects of the liquid metal flow on the calculation results of feed paths and hot spots have been discussed in detail in a “T” shape casting. An experiment has been done to validate the accuracy of the proposed model. The originating points of the feed paths indicate hot spots that manifest as shrinkage defects. And the numerical as well as experimental validations demonstrate the effectiveness of time gradient method for feed-path calculation.

Blasting Erosion Arc Machining of Turbine Blisk Flow Channel with Laminated Electrode

This paper presents a new process for machining the flow channels of wide gap shrouded blisk. It utilizes the blasting erosion arc machining (BEAM) process with laminated electrode which contains a number of curved flushing holes. The laminated electrode is an integration of several layers (slices) of electrode plates. As a strong inner flushing in the gap is the prerequisite for the hydrodynamic arc breaking mechanism for BEAM, curved flow slots are machined on each electrode plate surface to enable the working fluid to flow through and perform a strong inner flushing. Machining experiment with laminated electrode was carried out to demonstrate the feasibility of this novel machining technology. By optimizing the contour profile of the laminated electrode, the geometry of the inner slots as well as the feeding path, a stable and continuous electro-arcing process of BEAM was achieved and a blisk channel was machined efficiently.

Exponential and sigmoid-interpolated machining trajectories

In single-point metal turning and boring processes, a chip nest can often be created that is a hazard to part and operators alike. In order to mitigate this, a process called modulated tool path (MTP) machining was developed that superimposes a sinusoidal motion tangent to the feed direction onto the tool feed path to break chips. The sinusoidal motions are created under CNC control in the part program. In the current implementation, the sinusoidal motion is approximated as a series of short linear moves. Linear interpolation is currently used to create position and velocity commands to the axis servomotors at each control loop closure. Linear interpolation is a computationally heavy and dated method that is not well tailored to a sinusoidal trajectory. In this paper a new method called the sigmoidal interpolator is introduced that honors all physical constraints of a machining system while offering better tracking performance and lower accelerations than the linear interpolator, all while reducing the number of possible state transitions of the implemented software from approximately 17 to 4.

Movement patterns and feeding behavior of juvenile salmon (Oncorhynchus spp.) along armored and unarmored estuarine shorelines

Estuarine nearshore environments are impor- tant habitats for many organisms, including juveniles of several Pacific salmon species (Oncorhynchus spp.). These habitats provide shallow water and high prey productivity, but are increasingly modified by anthropo- genic activity including shoreline armoring, which dis- rupts connectivitybetween aquatic and terrestrial realms and artificially steepens the shore. Such effects may have adverse consequences for juvenile salmon, partic- ularly Chinook (O. tshawytscha) and chum (O. nerka), which are known to rely on shallow, productive near- shore habitats for foraging and refuge from predators during their outmigration from natal streams to the sea. We developed snorkel methods to quantify feeding rates, movement rates, and path complexity of juvenile salmon along armored and unarmored shorelines in Puget Sound, WA, USA. We found that juvenile salmon had relatively high feeding rates along all shoreline types, but that path straightness and movement rates showed some variation between armored and unar- mored sites. Feeding fish swam in more complex paths and were observed in larger schools than non-feeding fish, and path straightness and movement rate were negatively correlated with proportion of time feeding. Feeding behavior, school size, and movement rates also showed variation byspecies. Shorelinetype(armoredor unarmored)influencedjuvenilesalmondistribution,and unarmored shorelines appear to accommodate a greater diversity ofmovementpatterns thanarmoredshorelines. Our results show that juvenile salmon feed at high rates along armored and unarmored estuarine shorelines, thus decreased prey availability or altered prey resources are likely the most detrimental foraging effects of armoring in estuarine nearshore ecosystems.

Feasible pressure and axial feed path determination for fuel filler tube hydroforming by genetic algorithm

Successful fuel filler tube hydroforming largely depends on proper loading paths, that is, application of internal pressure and axial feeding during the forming time duration. Generally, two part quality criteria are considered in selecting the feasible loading paths: (a) minimum part wall thinning and (b) part wrinkle free. Due to the highly nonlinear nature of the tube hydroforming process, iterative finite element analyses with adjustments based on forming experience are typically conducted to design the loading paths. In this research, genetic algorithm was integrated into the finite element analysis–based optimization, resulting in enhanced determination of the feasible loading paths. Genetic algorithm is a heuristic search based on mechanics of natural selection. A pair of pressure and axial feeding profiles was represented by connecting genes making up to be a chromosome. In each search, mutation and crossover operations generated a new generation of chromosomes. Fitness functions were formulated to assess performance of the chromosomes reflecting the part quality. Generations after generations, the optimal chromosomes are found only when the evaluated fitness function value falls within a user-defined tolerance. Unlike the typical iterative finite element analysis approach, it was shown that the iterative finite element analysis augmented with genetic algorithm was able to determine feasible pressure and axial feeding paths autonomously. The current approach still requires a lot of simulation runs, which must be offset by high-performance computing resources.

Curvature effects on circular feed end-milling, part 1: modelling and simulation

Situations needing end milling along a polar feed path normally arise. This is the crux of the matter here. Investigation of such a milling operation led to a non-periodic delay differential equation for its regenerative vibration. To the authors' knowledge this equation is considered to be first of its kind. As a pointer to its validity, the equation is demonstrated to converge to the periodic delay differential equation of linearly fed milling process when the feed path radius approaches infinity. A cutting parameter called angular feed speed which is the ratio of prescribed feed speed to feed path radius is identified and demonstrated to contribute positively to stability of circular milling processes though relative to an equal feed linearly fed end-milling process it plays a progressive destabilising role when on increase. Analysis also led to the conclusion that there is more possibility of tool and machine structural fatigue in circular milling than in a rectilinear milling with equal feed. The subsequent parts of this work are proposed to be focused on the stability analysis and experimental validation of the presented model.

Mechanics and Dynamics of Helical Milling Operations

This paper presents analytical models dealing with time domain cutting forces and the time and frequency domain dynamics of helical milling operations. The cutting forces both on the side-cutting edges and on the end-cutting edges along the helical feed path are modelled by considering the tangential and the axial motions of the tool. The dual periodicity, which is caused by the spindle rotation, as well as the period of the helical feed of the cutting tool has been included. The models of the machining process dynamics and of the chatter stability problems are decomposed into two parts: the critical axial depth of cut, and the critical radial depth of cut, both of which are solved. The dynamics model allows the selection of processing parameters, including axial cutting depth, radial cutting depth, and spindle rotation velocity in the chatter-free zone and the prediction of chatter vibrations during helical milling. Experiments have also been performed for real machining observations in order to verify the chatter-free zone obtained from the analytical model.

Design of Screw Tooth Profile Based on Backlash and Design Method of Forming Cutter

Screw pump product often exhibits low volumetric efficiency and low service life due to the complicated screw rotor design, manufacturing and the non-uniform clearance. On the basis of analyzing the formation mechanism of screw clearance, a new design method of screw tooth profile based on the given clearance is proposed by using the analytic geometry theory in three dimensions. The transformation equations related to the feed path, screw tooth profile and the clearance in screw manufacturing process are then established. In combination with the isometric surface configuration of differential geometry, the screw cross tooth profile with the predetermined clearance is obtained. Furthermore, after investigating the spatial enveloping characteristics and geometry characteristics between screw and cutter in manufacturing process, as well as the shape and spatial position parameters of contact lines resulting from the movement for three combinations of machine tool, screw and cutter, a novel design method of forming cutter—shaped-position method is proposed, which is based on the discrete points for tooth profiles of screw manufacturing forming cutter. The method simplifies the solving model by virtue of converting the abstract spatial envelop into plane analytic geometry. It is shown to solve the problem that traditional meshing theory for cutter designing can not accurately calculate the cusp of tooth profile curves, and it therefore improves the tooth profile accuracy of forming cutter.

The Effect of Tension on a Fabric During its Liquid Treatment in a Roller-Equipped Machine with a Longer Feed

This article examines results from a study of the changes in tension and impulse along the elongated feed path of a fabric during its liquid treatment in a roller-equipped washing machine. It shows the effect of the impulse of the tensile force on the residual deformation of the fabric and presents an analysis of the results.

Electrode feed path planning for multi-axis EDM of integral shrouded impeller

Multi-axis electrical discharge machining is an effective approach for machining integral shrouded blade components. The key is to plan an interference-free and optimized tool electrode feed path while keeping the size of the electrode as large as possible. In this paper, a new electrode feed path planning method called tangent tracking was proposed. The electrode feed path planning can be formulated as a dynamic programming problem which consists of N discrete steps. In each step, the electrode posture optimization can be divided into pre-optimization and re-optimization. By using such a planning method, the electrode can have a smoother feed path and a larger size as compared with traditional methods. The machining tests for an integral shrouded impeller show that the tangent tracking method not only improves the machining efficiency, but also reduces the number of electrodes used.

Electrode Feeding Path Searching for 5-Axis EDM of Integral Shrouded Blisks

With a closed shroud on the top of their blades, the so-called integral shrouded blisks gained more and more applications in turbine engines. 5-axis electrical discharge machining (EDM) is regarded as the most effective approach for integral shrouded blisks machining. The tool electrode is shaped and reduced according to the profile of the flow channels to get enough space for electrode feeding. The key of EDM of integral shrouded blisks is to search an interference-free and optimized electrode feeding path. In this paper, a new electrode feeding path searching method called tangent tracking was proposed. Based on the dynamic programming methodology, the electrode feeding path searching process is decomposed into a number of electrode attitude optimization subproblems. Each subproblem can be further divided into two phases: pre-optimization and re-optimization. The purpose of electrode attitude pre-optimization is to make the tangent vector of the electrode centre curve coincide with that of the flow channel centre curve at the flow channels outlet section. If the electrode interferes with the blisk in the pre-optimization, the re-optimization needs to be conducted in order to find an interference-free attitude in the vicinity of the pre-optimized result. The tangent tracking method is validated by an integral shrouded blisk machining experiment.

Study on Optimal Reinjection Strategy of Geothermal Field: A Case Study from Tianjin, North China

Based on general characteristics of the Wumishan reservoir, the hydrogeology model is founded. And the problem of no more space for adding reinjection wells, the mathematical descriptions and influent of hydrothermal transportation, thermal break-through and the flow feed path with the different fracture zone were emphasied. According to simulat ion of the different models, a new ideal strategy about the reinjection wells was put forward, which can be set in the periphery of geothermal zone. And more heat can be extracted from the reservoir rocks through the reinjection activities. The pressure and temperature field of the reservoir will be controlled even though the injected cool water moves forward to the product zone, the water level and temperature field can be more stable with the reinjection models.

Modelling, simulation and experimental investigation of cutting forces during helical milling operations

The kinematics of helical milling on a three-axis machine tool is first analysed. An analytical model dealing with time domain cutting forces is proposed in this paper. The cutting force model is established in order to accurately predict the cutting forces and torque during helical milling operations as a function of helical feed, spindle velocity, axial and radial cutting depth and milling tool geometry. The forces both on the side cutting edges and on the end cutting edges along the helical feed path are described by considering the tangential and the axial motion of the tool. The dual periodicity which is caused by the spindle rotation, as well as the period of the helical feed of the cutting tool, has been included. Both simulation and experiments have been performed in order to compare the results obtained from modelling with experiments.

The Reliable Design and Implementation of an Automatic Glass Furnace Feeding Robot for the SME Glass Industry

This paper is a technical report which discusses a selfdeveloped automatic robot (machine) for glass furnace feeding. It was designed for use in a small-scale glass industry, in which most factories are still feeding small, old fashioned furnaces manually. The huge robot discussed in this paper is intended to substitute for exhausted workers. It was designed with four degrees of freedom and a planar manipulator structure, including X-axis and Y-axis translations, Z-axis rotation, and a belt scrolling motion for feeding the granular glass material into the furnace. The development and implementation of the mechanical and control systems are analyzed, including design considerations, motion using the teaching playback method, and feeding path planning. To ensure system safety and reliability, the necessity and the design of a redundant control systemare presented. Finally, the feeding quantity and quality control are discussed. Unlike other feeding machines, the robot fully utilizes robotic control components and technologies, which is considered another approach to real robotics application.

Yarn Feeding Change Analysis for Needle Bar Transverse Shifting of Carpet Tufting Machine

The needle bar transverse shifting would likely form the stop mark on the tufted carpet. Focus on this problem, through analysis the change in yarn feeding path and loop pile forming, construct the mathematical model of length change of yarn feeding in path and usage of loop pile forming while needle bar shifting. Base on the mathematical model analysis key influence for yarn feeding path change. The analyze result is useful for yarn feed compensation solution

Yarn Feeding Change Analysis for Needle Bar Transverse Shifting of Carpet Tufting Machine

The needle bar transverse shifting would likely form the stop mark on the tufted carpet. Focus on this problem, through analysis the change in yarn feeding path and loop pile forming, construct the mathematical model of length change of yarn feeding in path and usage of loop pile forming while needle bar shifting. Base on the mathematical model analysis key influence for yarn feeding path change. The analyze result is useful for yarn feed compensation solution