Study on the clogging mechanism of punching screen in sand control by the punching structure parameters

As an independent sand control unit or a common protective shell of a high-quality screen,the punching screen is the outermost sand retaining unit of the sand control pipe which is used in geothermal well or oil and gas well.However,most screens only consider the influence of the internal sand retaining medium parameters in the sand control performance design while ignoring the influence of the plugging of the punching screen on the overall sand retaining performance of the screen.To explore the clogging mechanism of the punching screen,this paper established the clogging mechanism calculation model of a single punching screen sand control unit by using the computational fluid mechanics-discrete element method(CFD-DEM)combined method.According to the combined motion of particles and fluids,the influence of the internal flow state on particle motion and accumulation was analyzed.The results showed that(1)the clogging process of the punching sand control unit is divided into three stages:initial clogging,aggravation of clogging and stability of clogging.In the initial stage of blockage,coarse particles form a loose bridge structure,and blockage often occurs preferentially at the streamline gathering place below chamfering inside the sand control unit.In the stage of blockage intensification,the particle mass develops into a relatively complete sand bridge,which develops from both ends of the opening to the center of the opening.In the stable plugging stage,the sand deposits show a“fan shape”and form a“V-shaped”gully inside the punching slot element.(2)Under a certain reservoir particle-size distribution,The slit length and opening height have a large influence on the permeability and blockage rate,while the slit width size has little influence on the permeability and blockage rate.The microscopic clogging mechanism and its law of the punching screen prevention unit are proposed in this study,which has some field guidance significance for the design of punching screen and sand prevention selection.

Microstructure,mechanical,and corrosion properties of surface of CuNi alloy produced by punching and annealing treatment

The influence of annealing on the formation of nanocrystalline of CuNi alloy surface was investigated by evaluating the microstructure, mechanical properties, and corrosion behavior of asprocessed condition （using severe plastic deformation by punching process） and its annealed condition. It was observed that the microstructure changed after annealing of punched sample using an atomic force microscope. Mechanical resistance and corrosion resis tance were also characterized using nanoindentation test, electrochemical test, electron work function, and micro tribometer test. It was found that the punched and sub sequent annealed samples have increasing hardness, elastic behavior 07）, and corrosion resistance. Therefore, anneal ing can lead to the final formation of nanocrystalline and corresponding stability of grain boundary, which are responsible for the increasing mechanical properties and corrosion resistance.

Simulation-Based Construction of Three-Dimensional Process Model for Punching Cartridge Cases

A method of constructing three-dimensional process model for the punching cartridge cases is presented based on DEFORM simulation analysis. Using DEFORM software,the finite element simulation models for the punching and forming process of cartridge cases are established,and the corresponding simulation result model of each intermediate procedure is obtained by continuously performing the forming process simulation. The simulation model cannot annotate size and process information due to poor interface between DEFORM software and CAD software. Thus,a 3D annotation module is developed with secondary development technology of UG NX software. Consequently,the final process model with dimension and process information is obtained. Then,with the current 3D process management system,the 3D punching and forming process design of cartridge cases can be completed further. An example is also provided to illustrate that the relative error between the simulation process model and the physical model is less than 2%,which proves the validity and reliability of the proposed method in this study.

Design of Automatic Feeding-and-Unloading Rotary Manipulator of Punching Machine

In recent years, punching technology of our country is developing fast. The proportion of hand feeding punching processing has gradually been replaced by automatic feeding and unloading mechanism, due to the low efficiency, poor security. In this paper, we design an automatic feeding and unloading system of the punching sheets of motor. The rotary manipulator consists of the transmission device, the mechanical arm device, the material suction device, the raw material automatic lifting device and so on. Adopting the rodless cylinder as the main actuator, the system realizes these beat movements of continuous lifting up, centering, conveying, unloading. According to the working principle and mechanical structure of the components in the system, the function and application of each component in the whole feeding-and-unloading system are analyzed in this paper.

Research of the Plastic Status Parameter and Instantaneous Clearance of a Punching Without Urr

The article mainly talks about the characteristic of common and fine punching and the quality of shearing edge. Although the common punching has been widely applied, the quality of shearing edge is very poor. The fine punching work-piece is better in quality. But it isn’t still been widely applied, because the structure of die is complicated and the manufacture of die and using pressure machine are expensive. A new fine punching processing without burr is put forward by discussing the plastic status and press stress status of the material which influence the quality of the punching work-piece in the deformation zone, it provides the plastic status of material to determine the parameter in the new processing and presents the maximum value of plastic deformation specific energy when the material reaches the plastic status. The author has analyzed the initializing clearance and instantaneous clearance of the ordinary punching. The instantaneous clearance of the ordinary punching process is instable. By studying the author brings forward a kind of punching process which initializing clearance and instantaneous clearance are stable, that is the negative clearance fine punching process. Because of using the negative clearance fine punching process, the material of sheared distorting section comes into the plastic state. The surface quality of the punching sheared edge is advanced 1.5 times than that of the ordinary punching. The recommended value of depth of the negative clearance punching has been given in this article.

Microstructure and texture evolution of nonoriented silicon steel during the punching process

The iron core of a motor is mainly manufactured from rolled nonoriented silicon steel using a punching process that leads to deformation and texture evolution at the cutting edge.According to this process,circular samples of nonoriented silicon steel were prepared by punching using blunt punch tools.In this work,two positions along the rolling and transverse directions at the cutting edge were analyzed.The main mechanisms of deformation for both positions are dislocation slip and formation of shear bands.These two mechanisms lead to similar texture evolutions for both positions.The dislocation slip leads to the formation of the{221}<uvw>component in the unbending area(200μm away from the cutting edge)and intermediate continuum-bent area.Additionally,the evolution of the texture from the{111}γfiber to the{110}fiber was observed at the extremity of the cutting edge with the formation of shear bands.

Study on Anisotropy and Punching Yield Strength of Knitted Fabrics

In terms of the structural characteristics, knitted fabrics are described as plane orthotropic body with two symmetric axes, and the stress in different direction is approximately linear with strain before the yield point.The punching yield strength can be predicted theoretically by developing a mathematical equation from anisotropic effect of knitted fabrics. The experimental results demonstrate the applicability of theoretical formula. Analyses also reveal that the factors influencing three-dimensional deforming performance can be divided into two categories: fiber-yarn-fabric structural features and deforming condition.

NEW PUNCHING MACHINE DRIVEN BY LINEAR INDUCTION MOTOR

The research and application of the punching machine driven by a linear induction motor(LIM)are introduced.The fundamental principle, construction, performance and application are described. Comparing this new model machine with its traditional form, the LIM driven punching machine has many great advantages, such as, simple construction, small size and mass, low production cost, short production time, easy to control, low noise and considerable energy saving.

Punching Shear Behavior of RC Slab-Column Connections with Nonrectangular Columns

This paper present an experimental study on the RC slab-column connections with nonrectangular columns, namely cross-shaped column, T-shaped column and L-shaped column. The punching shear deformation and strength characteristics of slab-column connections with nonrectangular columns under punching shear load are investigated. Nine specimens with the three kinds of nonrectangular columns and two reference specimens with square columns are tested. The tested ultimate loads, deformations, and failure modes of specimens are presented and discussed. Test results reveal that the punching shear strength and ductility of the connections with nonrectangular columns are higher than those of the corresponding connections with square columns, and also prove that the application of nonrectangular columns to flat-plate structure was feasible. Based on the test results, one method of calculating punching shear strength of connections with nonrectangular columns is proposed, which conforms with the current design practice of China. The test results on the punching shear strength are compared with the predictions of the formulas proposed by codes of several different countrie; and the predictions given by ACI code and China code are found to be conservative as the reinforcement ratio is increased.

Analysis on Micro Complex Shape Via Hole Punching on Low Temperature Co-Fired Ceramics

The quality of a via hole on a multilayer stack of Low Temperature Co-fired Ceramic (LTCC) tape is of utmost importance to its functionality. This paper investigates a substitute for the commonly used circular shape hole to a more complex one and its implications when different parameters such as sheet thickness, punch speed, travel distance and tool clearance are?changed. Fabrication of the punch tools and the punching process is carried out at the same machine, ensuring alignment. Two types of non-circular shape are chosen to carry out the experiment. Pre-sintered complex shape hole measurements show that while punch conditions such as speed and tool gap have?little effect on the size, sheet thickness and travel depth play a vital role in the overall dimension. Albeit having only a slight effect on the size, those parameters are significant in other aspects of hole quality. Post-sintering investigation is also observed and discussed.

The Development of Hi-Speed Punching System Using A Couple of Rotating Bodies

Punched steel sheets (metal sheets or foils) as thi n as 0.1mm are quite useful in the field of filters and various precision instrume nts. Thus, we have to develop more accurate and speedy techniques for punching t hin sheets. The traditional punching method uses an up-down pressing motion of a punch or a die on a strip of metal. The efficiency of this method is determine d by the speed of the motion. In the case of punching a sequence of tiny holes w ith a few millimeters’ interval, the speed of feeding a strip of metal to the p unching machine cannot exceed only a couple of meters per minute. We have de veloped a new technique for punching tiny holes with a pair of rotating bodies i n order to increase the feeding speed up to 100 meters per minute. Our proposed technique is shown in Fig.1 where the female tool has a round blade and the male tool has an M-shape boss. In addition, the setting of two tools i s alternating. The interference between them cannot occur because the clearance between the front and the back edge of the male tool and the female tool in the rotating direction becomes infinite in this configuration. An appropriate cleara nce is given for the thickness of the sheet between the side edge of the male to ol and the female tool. The punching itself is done by shearing. The side edge o f the male tool does contact with the female tool, but they cannot be interferin g. Our technique has another advantage to the traditional up-down pressing mach ine where the stamped out chips are hard to be discharged. It is quite easy in o ur proposed technique. Fig.2, 3 show a sample of punched material [TPP116A,+39mm88mm,Y,PZ#]Fig.1 The configuration of the punching parts using the sequential punching system.[TPP116B,+43mm155mm,X,BP#]Fig.2 A sample of punched material using the continuous punch ing lineFig.3 A exterior picture of a piece of punched steel foil(coi l) using the continuous punching For our developed high speed punching system, it is shown for (1) the configurat ion of punching tool and the punching mechanism, (2) the influence of male shape on punched hole quality, (3) the outline of continuous punching system, (4) the relation between punching speed and accuracy of hole pitch and hole dimensi on, (5) the mechanical property of punched metal sheet and (6) capability of hig her punching.

Effect of the Shear Reinforcement Type on the Punching Resistance of Concrete Slabs

Punching shear failure of flat concrete slabs is a complex phenomenon with brittle failure mode, meaning sudden structural failure and rapid decrease of load carrying capacity. Due to these reasons, the application of appropriate punching shear reinforcement in the slabs could be essential. To obtain the required structural strength and performance in slab-column junctions, the effect of the shear reinforcement type on the punching resistance must be known. For this purpose, numerous nonlinear finite element simulations were carried out to determine the behavior and punching shear strength of flat concrete slabs with different punching shear reinforcement types. The efficiency of different reinforcement types was also determined and compared. Accuracy of the numerical simulations was verified by experimental results. Based on the comparison of numerical results,?the partial factor for the design formula used in Eurocode 2 was calculated and was found to be higher than the actual one.

Punching and Local Damages of Fiber and FRP Reinforced Concrete under Low-Velocity Impact Load

In recent years, the development and application of high performance fiber reinforced concrete or cementitious composites are increasing due to their high ductility and energy absorption characteristics. However, it is difficult to obtain the required properties of the FRCC by simply adding fiber to the concrete matrix. Many researchers are paying attention to fiber reinforced polymers (FRP) for the reinforcement of construction structures because of their significant advantages over high strain rates. However, the actual FRP products are skill-dependent, and the quality may not be uniform. Therefore, in this study, two-way punching tests were carried out to evaluate the performances of FRP strengthened and steel and polyvinyl alcohol (PVA) fiber reinforced concrete specimens for impact and static loads. The FRP reinforced normal concrete (NC), steel fiber reinforced concrete (SFRC), and PVA FRCC specimens showed twice the amount of enhanced dissipated energy (total energy) under impact loadings than the non-retrofitted specimens. In the low-velocity impact test of the two-way NC specimens strengthened by FRPs, the total dissipated energy increased by 4 to 5 times greater than the plain NC series. For the two-way specimens, the total energy increased by 217% between the non-retrofitted SFRC and NC specimens. The total dissipated energy of the CFRP retrofitted SFRC was twice greater than that of the plain SFRC series. The PVA FRCC specimens showed 4 times greater dissipated energy than for the energy of the plain NC specimens. For the penetration of two-way specimens with fibers, the Hughes formula considering the tensile strength of concrete was a better predictor than other empirical formulae.

Effect of Needle Punching Process on a Chopped Strand Mat Composite with an Open Hole

The easiest and most reliable joining method is the mechanical joint with a bolt and nut or rivet. However, in the case of composite laminates, mechanical joint properties decrease because of lower interlaminar properties compared to in-plane properties around hole.?This study investigated needle punching process with the aim of improving the mechanical properties in the thickness direction of fiber-reinforced plastic composite laminates with an open hole. Needle punching process was applied to glass fiber chopped strand matused as the reinforcement for the composite laminates. Open-hole tensile tests and observations of end cross-sections after the tests were performed. The tensile properties and fracture mechanism of the specimens subjected to needle punching process were investigated. In addition, characteristic distance (a parameter for evaluating resistance to fracture in open-hole tensile test specimens) was also calculated to examine the effects of needle punching process conditions on fracture toughness. Tensile strength was improved by more than 15% by needle punching process. However, when a certain needle punching density was exceeded, the mechanical properties worsened. In addition, characteristic distance increased with increasing needle punching density. Thus, these results suggest that there is an optimal needle punching density with respect to strength and characteristic distance.

Theoretical analysis and development of a mechanism with punching device for transplanting potted vegetable seedlings

Several studies have indicated that potted vegetable seedling transplanting technology can greatly improve the ability of vegetable seedlings to resist cold,flood,drought,saline-alkali and pests.The existing transplanting equipment mostly adopts mechanical,electrical and hydraulic integration technologies with a complex structure and a high cost.To address the problems of the complex structure and low efficiency of existing transplanting equipment,a rotary transplanting mechanism for potted vegetable seedlings was developed through configuration analysis and optimization design.Through kinematic analysis of the transplanting mechanism,optimization design software was developed,and the parameters were optimized.A mechanism was developed for picking,transporting,hole punching and transplanting potted vegetable seedlings.The virtual simulation results showed that the maximum error of attitudes of the transplanting arm is less than 1.19°and that of the hole punching shovel is less than 1.7°.In this study,perforation,seedling harvesting and transplanting experiments were conducted through a bench test.The results showed that the specific trajectory and attitude of the potted vegetable seedlings transplanting mechanism conformed to the requirements of potted vegetable seedling transplantation and the success rate of seedling picking was 92.4%,which verified the correctness and feasibility of the rotary potted vegetable seedling transplanting mechanism.

面向P2P通信的UDP Hole Punching技术研究与实现

NAT(Network Address Translation),即网络地址转换,一定程度上解决了IPv4网络地址匮乏的问题,但也给面向P2P通信的应用程序以及协议造成通信方面的障碍。本文介绍了网络地址转换的基本原理以及其对P2P通信方式造成的冲击,简单概括目前主要的NAT穿透(NAT Traversal)技术,着重分析了UDP Hole Punching的穿透过程,最后给出一个轻量级的实现。

Punching shear behavior of recycled aggregate concrete slabs with and without steel fibres

A study on the punching shear behavior of 8 slabs with recycled aggregate concrete(RAC)was carried out.The two main factors considered were the recycled coarse aggregate(RCA)replacement percentage and the steel fibre volumetric ratio.The failure pattern,load-displacement curves,energy consumption,and the punching shear capacity of the slabs were intensively investigated.It was concluded that the punching shear capacity,ductility and energy consumption decreased with the increase of RCA replacement percentage.Research findings indicated that the incorporation of steel fibres could not only improve the energy dissipation capacity and the punching shear capacity of the slab,but also effectively improve the integrity of the slab tension surface and thereby changing the trend from typical punching failure pattern to bending-punching failure pattern.On the basis of the test,the punching shear capacity formula of RAC slabs with and without steel fibres was proposed and discussed.

Nonlinear numerical simulation of punching shear behavior of reinforced concrete flat slabs with shear-heads

This paper examines the structural response of reinforced concrete flat slabs,provided with flillyembedded shear-heads,through detailed three-dimensional nonlinear numerical simulations and parametric assessments using concrete damage plasticity models.Validations of the adopted nonlinear finite element procedures are carried out against experimental results from three test series.After gaining confidence in the ability of the numerical models to predict closely the full inelastic response and failure modes,numerical investigations are carried out in order to examine the influence of key material and geometric parameters.The results of these numerical assessments enable the identification of three modes of failure as a function of the interaction between the shear-head and surrounding concrete.Based on the findings,coupled with results from previous studies,analytical models are proposed for predicting the rotational response as well as the ultimate strength of such slab systems.Practical recommendations are also provided for the design of shear-heads in RC slabs,including the embedment length and section size.The analytical expressions proposed in this paper,based on a wide-ranging parametric assessment,are shown to offer a more reliable design approach in comparison with existing methods for all types of shear-heads,and are suitable for direct practical application.

基于实际预压载作业的自升式平台环境载荷图谱绘制新思路

The environmental load chart is an important technical support required for the jack-up drilling platform to facilitate its adaptation to different operating waters and ensure the safety of operation.This chart is a crucial part of the platform operation manual.The chart data are closely related to external factors such as water depth,wind,wave,and current conditions of the working water,as well as to the structural characteristics of the platform itself and the number of variable loads.This study examines the platform state under extreme wind,wave,and current conditions during preloading.In addition,this study focuses on the difference between the ultimate reaction force of the pile leg during preloading and the reaction force of the pile leg without considering any environmental load before preloading.Furthermore,the relationship between the difference and the new reaction force of the pile leg caused by the combination of different environmental conditions is established to facilitate the construction of a new form of environmental load chart.The newly formed chart is flexible and simple;thus,it can be used to evaluate the environmental adaptability of the platform in the target well location and provides the preloading target demand or variable load limit according to the given environmental constraints.Moreover,the platform can perform personalized preloading operations,thereby improving its capability to cope with complex geological conditions,such as reducing punch-through risks.This condition reduces the load on jacking system devices and increases its service life.

Corrosion resistance behavior of gradient microstructure induced by punching deformation and recovery treatment on cupronickel alloy surface

In this study, the gradient grain induced by punching deformation and recovery treatment on a cupronickel alloy surface sample were investigated, and their effects on corrosion resistance were measured by atom force microscopy(AFM), X-ray diffraction(XRD),electrochemical measurement, electron work function(EWF), and contact electrical resistance(CER). The cupronickel alloy surface experienced punching deformation for 60 min and recovery at 300 ℃ for 1 h to produce gradient surface. The grain size measured by XRD is bigger than that measured by AFM, due to X-ray intensity of95 % produced at the depth of 12-20 μm for the crystal planes of(111),(200), and(220). The gradient grain surface, compared to the original surface, shows a 13.7-fold decrease in passivation current density(i), and corrosion potential(Ec) increases by approximately 9.8 %. These results are attributable to the increase in EWF and formation of passivation film with better adhesion and compactness after treatment.