Showing papers on "Material flow published in 2000"

Self-organizing manufacturing control: an industrial application of agent technology

Abstract: We present an auction-based approach to manufacturing control. Workpieces auction off their current task, while machines bid for tasks. When awarding a machine, a workpiece takes into account not only the machine's current work in process, but also the outgoing flow of materials. If a machine's outgoing stream is blocked, eventually the machine will not accept a new workpiece, thus blocking its input stream as well. As a result a capacity bottleneck is automatically propagated in the opposite direction of the material flow. A unique feature of this mechanism is that it does not pre-suppose any specific material flow; the current capacity bottleneck is always propagated in the opposite direction of the actual flow, no matter what this flow looks like. This paper includes a detailed analysis of the mechanism, including a formal proof of its freedom of deadlocks. DaimlerChrysler evaluated the new control approach as a bypass to an existing manufacturing line. A suite of performance tests demonstrated the industrial feasibility and the benefits of the approach.

Analysis of the paper and wood flow in The Netherlands

Abstract: Current production structures require large amounts of primary materials and are not likely to be sustained without large implications for the environment. A good understanding of societal metabolism is likely to contribute to more sustainable production and consumption. Material flow analysis (MFA) intends to support this understanding by providing insight in material flows. In this article a new method for analyzing materials flows, called STREAMS, is tested. The method is applied to analyze the paper and wood flow through the economic system of The Netherlands. The method is based on data available from the so-called supply and use tables; these tables are made available by Statistics Netherlands and describe the economy of a country in terms of annual supply and use of goods and services by industries and consumers. The method proves to be very useful in analyzing the paper and wood flow in The Netherlands. The method provides detailed information about the final consumption of paper and wood, even for packaging materials and product parts made out of paper and wood. Trends are visible that statistical offices collect less physical data about material flows. This will make the construction of material flow analyses like this one more difficult in the future.

Sheet metal stamping die design for warm forming

Abstract: In metal stamping dies, by taking advantage of improved material flow by selectively warming the die, flat sections of the die can contribute to the flow of material throughout the workpiece. Local surface heating can be accomplished by placing a heating block in the die. Distribution of heating at the flat lower train central regions outside of the bend region allows a softer flow at a lower stress to enable material flow into the thinner, higher strain areas at the bend/s. The heating block is inserted into the die and is powered by a power supply.

Apparatus for converting a continuously supplied material flow into a single layer

Abstract: There is provided an apparatus which can simplify, expedite and enhance the segregation of undesirable particles from desirable particles in a multiple-layer flow wherein the desirable and undesirable particles are randomly intermixed with each other. This is accomplished by a stepwise reduction of the thickness of the flow to thus locate all or nearly all undesirable particles at or close to the exposed sides of the resulting relatively thin flow so that the undesirable particles can be readily detected and segregated from the thin flow. The stepwise reduction of thickness of the original flow is effected by a cascade of successive accelerating conveyors including a first conveyor which receives successive increments of the original flow from a vibratory trough, and a faster second conveyor which receives successive increments of the accelerated flow from the first conveyor and cooperates with an overhead conveyor to define a channel for advancement of the repeatedly accelerated original flow into the range of instrumentalities for detection and segregation of undesirable particles.

Material flow analysis of Chinese economic-environmental system

Abstract: The material flow theory and methodology have been applied to analyze quantitative characteristics of the total material requirement(TMR),the material intensity and the material productivity in the Chinese economic system during 1989 and 1996.The aim of the study is to estimate resource and environmental costs of the eco nomic development and to evaluate the sustainability of the economic environmental system.The conclusions are shown as follows:(a)The TMR of China is 1.6 times as much as that of the USA in 1994,which indicates that the resource and environmental costs of the economic development in China are enormous.(b)Even though the material requirement per capita in China is much smaller than those in the developed countries,the domestic material requirement per capita in China in 1994 is yet 1.1 and 1.5 times as much as those in the Netherlands and Japan,respectively.This result implies that the Chinese national economy is mainly depended on the consumption of domestic natural resources.(c)The ratio of GNP to TMR in China in 1994 accounted for only 2%～6% of the ratios in the developed countries,which shows that the efficiency of the resource utilization in China is very low.In terms of the composition of the TMR,the largest contributor is the excavation for infrastructure,secondly is the input and its ecological rucksack of fossil fuels,thirdly is the input and its ecological rucksack of construction materials and fourthly is the soil erosion.If the exploitation volume of water resources would be brought into the material input of the economic system,the tap water supply would account for more than 50% of the TMR.In the present stage of Chinese economic development,coal,construction materials,iron,crops and fresh water are the most important material requirements; the excavation of water conservancy projects is the strongest disturbing force to the environmental system and the soil erosion is the most significant indicator of the ecological degradation.Taking the present material productivity of China as the start point,we propose a mid and long term strategic goal in connection with the four fold and the ten fold increase in resource efficiency for 2025 and 2050,respectively.This kind of national goal will meet the overall target of the resource consumption towards the global sustainable development.

Hopper, or bin, screw feeder construction controlling discharge velocity profile

Abstract: A bin or hopper, preferably with one-dimensional convergence, has a slot outlet at its bottom for discharging bulk solid particulate material (such as coal, wood chips, sugar, plastic pellets, etc.) to a screw in a trough. The screw has varying flight diameter, shaft diameter, and average pitch along its length to a discharge so as to provide substantially uniform material flow velocity distribution along the slot outlet. One or more flow rate adjusters may regulate flow of material being transported by the screw. Each flow adjuster may be a vertical plate with a substantially straight-across bottom curved about a substantially horizontal axis, or with a bottom two-dimensional curvature.

Comparison of methods for calculating the influence of asymmetry in strip and plate rolling

Abstract: The effect of different work roll diameters, different circumferential speeds of work rolls, and different friction for top and bottom side on roll parameters, especially on curvature of outgoing material, is investigated. Three methods, which are all based on the theorem of the upper bound of total power, are discussed. Their results are compared with experimental data of Juretzek. They differ in the kind of velocity field for the material flow in the roll gap. The first makes use of a polynomial global velocity field. The second employs bilinear quadrilateral finite elements, which are fixed to space, while the stationary rigid plastic material flow goes through (stationary FEM). The third field consists of rigid triangles which can slide along their contact lines. The last method produces a formation of shear lines, which is in good coincidence with that of the zones of high strain rate, given by stationary FEM. Results of parameter studies using stationary FEM are shown as relationship between dimensionless characteristic numbers. At last a comparative analysis of the effectiveness of the different methods is given.

The optimization of material flow in production

Abstract: Market demands are different: they tend to require individual, customized products of high reliability and high quality and also produced in right time. Material flow optimization is an indispensable step to be taken. The proposed optimization method is material flow analysis, which is giving an insight of the production organization of a company and its evaluation at different organizational levels. The analysis is based on a technological database and on the organization of individual departments of a company. It enables a material and information flow analysis as well as an analysis of the department and machines layout respectively. The result of the analysis is material flow rationalization, thus minimizing production costs.

Application of the finite element method in cold forging processes

Abstract: The demand for more efficient manufacturing processes has been increasing in the last few years. The cold forging process is presented as a possible solution, because it allows the production of parts with a good surface finish and with good mechanical properties. Nevertheless, the cold forming sequence design is very empirical and it is based on the designer experience. The computational modeling of each forming process stage by the finite element method can make the sequence design faster and more efficient, decreasing the use of conventional "trial and error" methods. In this study, the application of a commercial general finite element software - ANSYS - has been applied to model a forming operation. Models have been developed to simulate the ring compression test and to simulate a basic forming operation (upsetting) that is applied in most of the cold forging parts sequences. The simulated upsetting operation is one stage of the automotive starter parts manufacturing process. Experiments have been done to obtain the stress-strain material curve, the material flow during the simulated stage, and the required forming force. These experiments provided results used as numerical model input data and as validation of model results. The comparison between experiments and numerical results confirms the developed methodology potential on die filling prediction.

Determination of economic order quantities (EOQ) in an integrated material flow system

Abstract: The material flow system is the backbone of a manufacturing system as it provides both physical and operational structure. Each component (material handling, until load size, storage space, layout, etc) is a difficult problem to address on its own; however, it is imperative that components be addressed concurrently due to their interactions. This paper explores the relationships between the components in the material flow system with respect to determining the economic order quantity. This is in contrast to the traditional EOQ model, which considers only order cost, inventory cost, and demand, ignoring other material flow system issues. A multi-item economic order quantity (EOQ) model under a storage space limit is considered with respect to material handling equipment selection and requirements, unit load size, and flow path selection. The integrated material flow system problem is mathematically formulated as a large scale, nonlinear integer programming model and a heuristic solution procedure is develo...

Bookbinding cover producing device has material flow of boards and covers rising towards horizontal resting surface of machine

Abstract: The cover producing device has the material flow of the boards (4, 5) and of the book covers (2) rising as far as the output guide device (50) to the horizontal resting surface (7) of the machine. The extra height compensates for the loss of height in the board magazine and in other components of the flow system.

An integrated material flow system approach for determining the economic production quantity (EPQ)

Abstract: Traditionally, the analysis of material flow systems has focused on each of the individual components of the system separately (i.e. material handling, production lot size, unit load size, flow pat...

Rolling of annular workpieces takes place at least in two stages, with predominantly axial and tangential material flows of the blank produced respectively at the first and second stages

Abstract: The rolling process takes place at least in two stages. Firstly a predominantly axial material flow of an annular blank (5) is produced using the profile roll (1) and at least two further outer rolls (6). Secondly a predominantly tangential material flow is produced by using the mandrel roll and the profile roll until the required profile depth and outside diameter of the workpiece are attained.

Applying heat and mass balance theory to determine the flow rate for the measurement of benthic material flux in a flow-through system

Abstract: Movement of water overlying the sediments has not been taken into consideration in most of the experiments conducted to estimate the dissolved material flux from the sediment. Even in recent experiments that incorporated the stirring motion, interpretation of the data is difficult, because the mixing rate used may be different from actual mixing rate in the field. We propose a method to estimate the in situ mixing rate that should be used to set the flow rate in a flow-through core incubation system. The flow rate is calculated from the vertical mixing rate of the water that is deduced from the heat diffusivity. Release rates of NO3+NO2–N obtained from our flow-through incubation system were higher by 1–3 orders of magnitude than those from the conventional diffusion calculation method that estimates the flux from the gradient of nutrient concentration across the sediment-water interface. Increase in NO3+NO2–N flux is considered to be due to intensification of the nitrification process as a result of an increase in dissolved oxygen (DO) supply with the motion of water. DO supply is also considered to be an important factor controlling macrofaunal abundance and consequently their excretory contributions to the fluxes of dissolved organic nitrogen as well as NH4–N. From this point of view, we strongly recommend the application of heat and mass balance theory to estimate nitrogen flux using a flow-through experimental system.

Study on the method for calculating influence of mass flow on energy consumption in steel manufacturing process

Abstract: Based on the concept of fundamental mass flow chart, all possible situation of ferric material flow in steel manufacturing process have been analyzed. The influence expressions of mass flow of deviated from fundamental mass flow chart on energy consumption were put forward.

Coating material supply system

Abstract: PROBLEM TO BE SOLVED: To provide a coating material supply system, whereby the precipitation of aggregate in a coating material transporting hose in the case the coating is not carried out is effectively prevented. SOLUTION: The coating material supply system possesses a syringe 4 provided with a discharge part 401, a piston 5, a coating material flow passage 6 formed in the piston 5, a coating material supply means 7, a 1st valve 8, a coating material transporting means 3 one end of which is connected to the discharge part 401 of the syringe 4, a spray gun 2, a circulation means 15 connected to the spray gun 2 and a 2nd valve 16. The spray gun 2 is provided with a circulation flow passage 201 one end of which is connected to the coating material transporting means 3 and another end of which is connected to the circulation means 15, a coating material ejecting part 202 connected to the circulation flow passage 201, and an opening and closing means 203 for the coating material ejecting part 202.

Method of drain water feed through pressure pipe circuit

Abstract: The method of feeding drainage water through a network with pumping stations involves separating the water flow into a large-solids carrying coarse material flow and an adjacent coarse material free fine-solid flow. The fine solids flow is hydraulically fed through the network and the coarse solid flow is fed pneumatically through it.

Material spreader for timber material panel manufacture has rotating rollers with interlocking elastic spring parts to dissolve material flow particles when passing between rollers

Abstract: The device has two opposite rotating rollers with interlocking parts to dissolve clumps contained in a material flow. The parts (15) are elastic and/or mounted elastically and/or turnable on the rollers (6,6'), and aligned in centrifugal force direction. The particles of the material flow when passing between the rollers is charged impulse-like and dependent upon their specific gravity. The parts are curved die-cast or flat steel or spiral spring elements (17) with profiling. There is also a shaft to receive foreign matter with high specific gravity.

On Optimization of Unreliable Material Flow Systems

Abstract: The paper suggests an approach for optimizing a material flow system consisting of two work-stations and an intermediate buffer. The material flow system may be a production system, a distribution system or a pollutant-deposit/removal system. The important characteristics are that one of the work-stations is unreliable (random breakdown and repair times), and that the performance function is formulated in average terms. The performance function includes random production gains and losses as well as deterministic investment and maintenance costs. Although, on average, the performance function is smooth with respect to parameters, the sample performance function is discontinuous. The performance function is evaluated analytically under general assumptions on cost function and distributions. Gradients and stochastic estimates of the gradients were calculated using Analytical Perturbation Analysis. Optimization calculations are carried out for an example system.