Showing papers on "Material flow published in 1977"

Predicting the Strain Rate in the Zone of Intense Shear in which the Chip is Formed in Machining from the Dynamic Flow Stress Properties of the Work Material and the Cutting Conditions

Abstract: In previous applications of an approximate machining theory in which account is taken of the strain rate and temperature dependence of the work material flow stress properties it has been found necessary to use an empirical relation to determine the maximum value of the maximum shear strain rate in the chip formation zone. In this paper the machining theory is further developed so that this strain rate can be obtained as part of the solution. Predicted values found in this way are shown to be in excellent agreement with the rather limited number of experimental strain rate results which are available. The paper ends by showing that if the work material is allowed to approach the ideal constant flow stress material usually assumed in slip-line field theory then the predicted strain rates become extremely large. However, it is still found necessary in calculating the corresponding hydrostatic stresses to use the stress equilibrium equations for a variable flow stress material as the variable flow stress terms do not diminish as rapidly as might have been expected.

A Model of a Closed-Loop Conveyor with Random Material Flow

Abstract: A closed-loop conveyor with one loading station and one unloading station is considered. The material arriving at the unloading station is modeled as a stationary stochastic process. An analytical solution for the probability distribution of the material flow leaving the unloading station is presented. It is shown that the storage feature of the closed loop can be utilized to smooth the random fluctuations present in the input flow. This smoothing is quantified by the variance reduction factor, which is the ratio of the variances of output flow and input flow. The variance reduction factor is related to the conveyor capacity and a linear decision rule for unloading.

Method and a device for adding material in an air stream to a nozzle

Abstract: Spraying of materials, which prior to the spraying operation have been mixed from two airborn material flows in a spray nozzle, results in a high wastage rate. It has now been found that this wastage can be highly reduced, if in an appropriate apparatus one of the material flows is restricted, whereas the other material flow is allowed to expand when introduced axially into and mainly in the center of the first restricted flow of material, the second expanding flow of material thereby further being used to create by ejector effect a suction acting upon the restricted flow of material.

Free-running material e.g. pulverised coal charging system - with flow rate controlled gate setting and carrier gas admission

Abstract: Free-running bulk material, e.g. pulverised coal, can be charged into a pressure vessel, e.g. a gasification reactor, by passing it through a flow rate metre. Its actual readings are compared with a desired value and the cross-section of the passage is controlled by the difference. The material flow also receives a gaseous transport medium as a function of the flow rate before it enters the admission line to the reactor. The result is a uniform charging rate of a reactor even if several admission lines are used. Any overflow or clogging of the conveying lines is eliminated.

Material handling system for wide range of materials and flow rates

Abstract: Continuous flow at various material flow rates through a pneumatic transport system of a wide variety of granular and hygroscopic materials over a wide range of moistures, sizes and weights is achieved by gravity feed through a dispensing hopper having a portion of the side wall surface shaped as an irregular hyperbola. Thus, shipboard mounted or other portable transport system may be used to load or unload ship holds with grain, cement, seed, sand, sugar and other such materials at high flow rates through input and output hoses conveying materials from one location to another. The same system may be used at lower material flow rates achieved by lower density of materials in the pneumatic stream, thereby to sandblast and paint the ship hulls for example. Special flow rates may be chosen to adapt to given material characteristics or transport needs. Separation of input and output air transport paths is achieved by a centripetal air flow chamber filling the dispensing hopper with a store of the materials from which they continuously flow into a pneumatic conveyor tubing at controllable rates.

Method of producing an optical fiber

Abstract: A method of and a device for a simultaneous extrusion of multi-component co-axial rods with very uniform, centered cores. A block of cladding material has core material co-axially contained in the geometric relationship desired for the ultimate product, and extrusion is by pressure opposite to the direction of material flow.

Dynamic Scattering and Material Flow in a Nematic Liquid Crystal

Abstract: Results are presented which show how defects in a nematic liquid crystal can be used to investigate material flow when external electric fields are applied. These results include measurements of the size of flow cells, which were created between the electrodes by an electric field. The electrodes, which were made of transparent conductive coated glass, were placed in a vertical position so that flow cells could be observed from the top while dynamic scattering was observed when viewing normal to the electrodes.

Continuous flow expander for expanding particulate material

Abstract: A continuous flow expander for expanding particulate material, more specifically for grain or cattle fodder, is provided whereby material to be expanded is transported in a substantially continuous manner through a pressurized region wherein it is heated, steamed and pressurized by a counterflow of dry steam created from available city water by a recirculating steam boiler. The material is then ejected by another flow of dry steam created from available water into a lower pressure region for expansion. Enthalpy in the ejection region is automatically maintained within a predetermined range, for grain or cattle fodder from 450 to 750 BTU per pound of moisture being ejected, regardless of the moisture content of the material, by varying steam boiler output and, if necessary, material flow rate. An expanded product requiring no further drying prior to use or storage is thereby provided with minimum energy use.