ISSN:0032-3888    

DOI:10.1002/pen.760240902

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760240903

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractIn the most commonly used scale‐up method of plasticating extruder screws, the screw channel depth is increased by the square root of the diameter ratio while the screw RPM is decreased by the square root of the diameter ratio such that the output rate increases proportionally to the square of the diameter ratio. This scale‐up method, largely based on the pumping function of the screw, often leads to a higher melt temperature, a higher screw horsepower consumption per unit output rate and an inferior melt quality from the larger diameter screw. Analysis of the common scale‐up method reveals that, although the shear rate in the melt is kept constant, the average residence time and the peripheral screw speed are increased for the larger diameter screw. Our recent study on the melting mechanism also reveals that the melting capacity increases less than the pumping capacity. A detailed examination of the common scale‐up method in this paper shows that the pumping capacity and the solid conveying capacity increase more than necessary while the melting capacity increases insuffi

ISSN:0032-3888    

DOI:10.1002/pen.760240904

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe two main materials used for insulating wire are plastic and pulp. With the introduction of digital transmission techniques, there has been an increasing demand for improved cable quality, thereby stimulating an investigation of the insulating process in order to improve quality. The increasing availability of digital computers enabled mathematical models of the insulating process to be constructed, which together with experimental work, provided a basis for the installation of computerized control systems. This paper reviews three such models which were developed and are being used. These comprise a model for screw extrusion, a model for melt flow in the wire coating die, and a model for the subsequent cooling of the insulated wire (or cable). Relatively little work was done in the area of dynamic simulation of the insulating process and we found computer control systems could be relatively easily installed in production provided high level software process modules with interfaces to a high level programming language were available on the system. It was found that simplified control schemes were usually the most effective in production. Two computer control installations to illustrate this viewpoint are described—a multiline central computerized control system, and a single‐line microprocessor‐based s

ISSN:0032-3888    

DOI:10.1002/pen.760240905

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe residence time distribution (RTD) in a fully intermeshing, corotating twin screw extruder was determined with a stimulus‐response technique. In addition to varying three process parameters (i.e. throughput, screw rotational speed, and barrel temperature), two screw configurations were also studied: one containing four kneading block mixing sections, and the other consisting only of regular screw bushings. Although screw configuration was an important variable, it was found that for both configurations the throughput had the largest effect on RTD. The screw rotational speed was second in importance, and the barrel temperature change produced no effect.A fluid mechanical model based on the fluid flow in a partially‐filled rectangular channel was used to explain the experimentally observed dependence of RTD on the process parameters. Reaction engineering approaches were adopted to compare the RTD results of two screw configurations with two idealized fl

ISSN:0032-3888    

DOI:10.1002/pen.760240906

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractA combination of shear and extension is encountered in the squashing flows of heated polymer particles. Extensional rate affects the non‐Newtonian viscosity in determining the flow field in the squashing of cylindrical particles, but both the extensional and shear rates are equally important for disc‐like particles.A viscous‐type constitutive equation is used for simplicity. The solution of the momentum equations satisfying no‐slip boundary conditions leads to a particle flattening equation that can predict flattening ratios of nonisothermal particles in terms of rheological parameters and dimensionless groups of process variables. Application of this analysis to roll fusing of toner particles in copiers is described in a companion article in thi

ISSN:0032-3888    

DOI:10.1002/pen.760240907

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper deals with squashing of toner particles in a variety of paper topographies in the roll fusing of toner images in xerographic machines. The model developed can be used for predicting the mean spreading ratio of toner particles related to fix level with given rheological properties and fusing temperature and pressure.The deformation of toner particles is solved with respect to the asperity pressure encountered in the contact between the roll and the paper surfaces. Various contact situations are considered, among them: toners on smooth papers, on tops of paper asperities, and at valleys of a paper surface. In addition to rheological properties and fusing conditions, toner spreadings also depend on toner size, paper roughness, and the rubber modulus of the fuser roll.Based on an integration algorithm, statistical averages of toner spreadings can be computed in terms of distribution functions of toner and paper asperity height. Comparisons of theoretical predictions with measurements show good agreement over a broad range of data.

ISSN:0032-3888    

DOI:10.1002/pen.760240908

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe hierarchy of mathematical models of injection molding is reviewed. Compatibility of the models of the hierarchy, usefulness of simultaneous applications of models formulated on several different levels of the hierarchy and compatability between physical approximations leading to the formulation of a model, and mathematical approximations used to solve numerically the governing equations of the model are discussed. This review is intended to facilitate the search for a model that is best suited to a given need and to indicate future research.

ISSN:0032-3888    

DOI:10.1002/pen.760240909

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractSome aspects of injection‐molding dynamics were studied using a laboratory injection‐molding machine operated under the control of a microprocessor‐based servocontrol system. Two types of experiments were performed: deterministic tests which introduced step changes in the servovalve opening and stochastic tests using pseudo‐random binary sequence (PRBS) perturbations of the servovalve. Deterministic models were written for the hydraulic and nozzle pressures which were in good agreement with the experimental data. A stochastic transfer function‐noise model was obtained for the nozzle pressure, but an adequate model was not found for the hydraulic pressure. The agreement between the nozzle pressure stochastic model and the corresponding step test model was sat

ISSN:0032-3888    

DOI:10.1002/pen.760240910

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractA model is proposed for the treatment of heat transfer with crystallization during plastics processing in general, and injection molding in particular. The model incorporates experimentally determined crystallization kinetics parameters. It permits the calculation of the distribution of both temperature and crystallinity in the molding. Theoretical predictions are in good agreement with experimental measurements in both injection molding and a prototype apparatus.

ISSN:0032-3888    

DOI:10.1002/pen.760240911

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY