In the drastically changing business environments and high-paced evolution of information technologies, requirements for production become more complex and diversified around the world. Flexibility evaluation methods using life-cycle cost analysis have been developed for typical production volume fluctuations. In this paper, as a next step, the more general evaluation method is demonstrated taking a hint from the frequency characteristics of control systems; by using dynamic programming techniques the flexibility parameters are adjusted to quantitative fluctuation in order to maintain the efficiency in production system. The effect of the method is verified from the application in the production systems developed at DENSO CORPORATION.
Under the volatile economic situation in recent years, manufacturers need to have a high level of flexibility to manage a wide variety of products in varying quantities within a short delivery lead time. But in dynamically changing manufacturing environment, it is quite difficult to optimize interdivisional scheduling which reduces total manufacturing cost of all divisions such as raw material procurement, machining, assembling and shipping following fluctuations in demand. To solve this problem, we propose a new interdivisional scheduling method which decomposes the whole problem into process-dependent problems using inter-process lead time and cooperates between processes by applying Lagrangian decomposition coordination method. Additionally we designed the method which can adjust inter-process lead time automatically in order to respond to the changing demand of each item. Then we examine the effectiveness of this method by numerical experiments.
Recent semiconductor manufacturing feature is high-product-mix and small-lot-size production, and the productivity becomes much worse owing to the short life cycle of production goods and the frequent change in the specification and demand within a short time period. Therefore, a solution method to optimize the efficiency, cost, and TAT (Turn Around Time) in a comprehensive way is indispensable. In this paper we applied the Lagrangian Decomposition and Coordination Method, which is the well-known cooperative scheduling methods, into an abstracted model of the actual Semiconductor production line, which has a feature of a re-entrant flow model, and studied the characteristic concerning the utilization of the model.
This research proposes a new model representing multi-layered dynamic supply chains and a new negotiation process among components. The proposed model consists of three components named clients, manufacturers, and suppliers. The manufacturers generate and send both the orders of the parts to the suppliers and the offers of the products to the clients. The manufacturers continue to modify their production schedules after sending their orders of the parts to the suppliers, in order to improve their schedules to manufacture the ordered products. Therefore, the manufacturers are able to satisfy the requirements on the delivery time of the ordered products, even if the possible delivery time from suppliers does not satisfy the required delivery time from the manufacturers. The effectiveness of the proposed model and negotiation processes is verified through some computational experiments from the viewpoint of profits.
This paper discusses the vehicle routing problem with time windows and stochastic demands. All customers have the penalty functions of the time to arrive at them, respectively (the penalty for time windows). The customers' demands are characterized by a known probability distribution and a customer's actual demand is only revealed when the vehicle reaches the customer location. When the total demands of customers on a route exceed the capacity of the vehicle, extra path to depot for replenishment must occur. This problem can be described as the problem of designing least travel cost routes from one depot to a set of customers. We express the travel cost by the sum of the planned distance, the expected distance of extra path to the depot and the expected penalty for time windows. The planned distance and the expected distance of extra path to the depot can be obtained immediately when a route is given. However the expected penalty for time windows cannot be obtained even if a route is given. Because we must determine the time to arrive at each customer in order to obtain the expected penalty for time windows, that is, we must consider the problem of determining the time to arrive at each customer in a given route so that the expected penalty for time windows is minimized. Therefore we propose the method for solving the problem of determining the time to arrive at each customer. Then we formulate the vehicle routing problem as a set covering problem and we propose the solution method using column generation approach.
Considering the environmental load of material and energy consumption, many approaches to product design and manufacturing have been discussed from an ecological viewpoint. In this paper, we propose the architecture that promotes module level reuse in order to reduce the environmental load in product manufacturing and use. The system architecture stands on an agent-based sensor network and a modular reusable desige. In this paper, an information system called eco-agent systems to promote reuse and recycling processes of product modules is proposed. This system uses a sensor system for diagnosing each product module and managing reuse plan. Since the system can always grasp conditions of modules, it can start reuse planning while users use the products and reduces the lead time to remanufacturing. As a simple realization model of the proposed architecture, a system for a motor-assisted bicycle is developed by using wireless small sensor network and network agent systems. The system monitors product conditions and searches the next owner of each module for promoting reuse and avoiding product waste as much as possible. Case studies show some practical use and merits of this architecture.
In this report, an interoperable collaboration using standardized technologies for manufacturing systems is proposed. Today, many software products such as BOM, production schedulers, MES and controllers are available in the market. Integrating these products into a whole manufacturing system is difficult and expensive because of differences between architectures adopted. IEC 62264-1 had been published as a referencing architecture for a guideline of integration of manufacturing systems. The collaboration protocol between products or packages based on the IEC 62264-1 has been proposed from MESX joint project. The MESX protocol provides integration method using XML technologies. A demonstration system using the protocol had been developed by MESX joint project. We propose the knowledge representation of MESX, and describe collaboration between products of level 3 and 4 of IEC 62264-1 in the demonstration system.
In this paper, we propose and implement a 3D measurement system by using defocus images obtained from a single camera. Depth from Defocus (DFD) is one of methods to estimate depth information from a pair of two defocus images. In former researches, target object to be measured must be inside between the two images. We propose an algorithm to overcome the limitation, and have implemented the system by a high-speed camera and telecentric lens. We verified the efficiency of the proposed system by some experiments.
Air arc plasma cutting, which does not requires special orifice gas, is applicable to a wide range of small-to-medium-sized manufacturing industries because it is simple and economical. However, one of its limitations is that angular precision of the bevel produced by this method is inferior to other cutting methods, thereby preventing its widespread use by industries that require high cutting precision. The author investigated the specifications of a general-purpose arc plasma cutting machine of the swirling-flow type currently available in Japan, focusing on the plasma the parameters that can provide higher quality cutting and match the performance of oxygen arc plasma cutting. The investigation was performed under operating conditions that differ from those recommended by the manufacturer.
In recent years, the demand for five-axis control machining centers is getting higher and higher to achieve process integration and high accuracy. On the other hand, it is generally difficult for five-axis control machining centers to realize the same motion accuracy as or higher motion accuracy than three-axis control ones due to the increase in two rotary feed axes in addition to three linear feed axes. Various five-axis control machining centers with suitable constructions have been developed for their effective purposes. At that time, it has been considered that Trunnion type five-axis control machining centers can realize the high motion accuracy relatively easily, based on actual evaluation data and experience. To make sure this fact, a five-axis control machining center which has Table-on-Table type construction, different from Trunnion type, was planned in terms of good operability. Its motion accuracy was measured and compared with the Trunnion type one by use of DBB 5 method. As a result, it is confirmed that Table-on-Table type five-axis control machining center has higher motion accuracy than Trunnion type one as well as good operability.
Optimally designed surgical drills are necessary to avoid thermal damage to osseous tissues and to ensure rapid and accurate drilling during bone fracture surgery. Bony necrosis is believed to occur at temperatures of 50℃ or more and is strongly related to the length of exposure to high temperatures. A drill with a low thrust force that suppresses heat generation is thus necessary to avoid bone necrosis. This study quantitatively examined the effects of surgical drill geometry on heat generation and thrust force using experimental design, analysis of variances and statistical technique. The helix angle, web thickness, and point angle of the fundamental drill elements were evaluated to determine the optimal drill geometry at various cutting and feed speeds. Thrust force and drilling temperature were measured while drilling porcine femoral bone to examine the influence of drill geometry on these factors. A 40° helix angle, 23% web thickness, and 90° point angle were found to be the optimal choices for suppressing heat generation.
A new framework of identifying the crack position in a structural member in terms of numerical simulation is presented. In this methodology, the extended finite element method (XFEM) is used to analyze the vibration problem of the structure which has a straight crack on its surface. To identify the position of a crack, the gradient of a evaluation function is used, and that function is calculated by using the eigen frequencies of the structural members both with real crack position and with estimated crack position. In the numerical examples, two dimensional cantilever beam members are used, and the identification of crack position has conducted. In some cases the evaluation function has several residual points, or has very flat distribution around the real crack tip. To identify the crack position certainly, setting up several starting points becomes reasonable approach.
Quasi-Modal technique is used for rotor-blade coupled torsional vibration analysis, because of its unique characteristics to provide a visual reduced model. In this paper we propose the hybrid method to calculate rotor-blade coupled torsional vibration of the model rotor of two disks with continuously coupled blades using FEM based quasi-modal parameters of blade-disk system. The result of hybrid method is compared with the full FEM analysis of the model rotor. The hybrid method shows the good accord with the full FEM analysis. This hybrid method has the advantage for faster design calculation repetition. The rotation test of model rotor is executed and measured results are compared with the calculated results to show the good accordance. The calibration procedure of modal parameters based on the measured blade-disk frequencies is also presented in order to show that the quasi-modal modeling is practicable method to feed back test results to analytical model for better accuracy.
The magnetic gradient levitation is also called as a mixed-μ levitation and composed of at least three materials with different magnetic permeability, namely iron, air and superconductor. This levitation method enables to levitate the iron rotor keeping no contact with any parts. Utilization to flywheel is expected considering of the reduction of rotational loss and cost-down of rotor. We constructed the levitation experimental device which arranged the circular superconducting coils, the cylindrical magnetic shielding plate made of NbTi superconductor, and the cylindrical iron rotor farther inside in series. We tried the rotational tests of the iron rotor. As a result, the non-contact levitation keeping rotation was realized, but the unstable whirling phenomena appeared at the high rotational speed over 2100min^<-1>. We analyzed this behavior by the aid of finite element magnetic analysis and revealed the mechanism of this instability.
Transfer Path Analysis (TPA) is a useful tool for the reduction of automotive noise and vibration. TPA offers the information about the contribution of the transfer paths and analysts would take effective measures with this information. However it could not seem easy to apply to the automotive body structure itself. One of the reasons is complexity of the vibration transmission in the body structure that is assembled by many members and that should be analyzed by manifold vibration transfer paths. This means there are a lot of transmitted forces an transfer functions defined in the assembled structure. This paper presents two proposals in TPA using finite element model: 1) technique in contribution analysis to the structure with manifold and continuous transfer paths, 2) visualization technique of the influence degree for the reduction of the response of the structure. In the contribution analysis, the transmitted force at every node is accurately calculated with the proposed element force calculation, and the element plays a part of a transfer path. The influence degree is newly defined by the result of the contribution analysis and assists analysts to obtain measures more efficiently. These two techniques let the analysts easy to understand the vibration transfer characteristics by the visualization. The application to an automotive body structure validates the effectiveness and usefulness of the proposed approach.
A multi-axis force/moment sensor, which can measure force and moment, is useful for robotic force control. However, the smallest multi-axis force/moment sensor has excess height, which restricts postures in tasks by a robot hand. In this paper, we aim to develop the thin-type four-axis force/moment sensor that can measure the twisting moment on the finger cushion of a robot hand and improve performance of this sensor by structural optimization, including strain gauge. As a result of applying structural optimization techniques using response surface method and desirability function on the four-axis force/moment sensor by finite element analysis, we obtained optimum design variables and validated the effectiveness of the proposed techniques. Finally, we made the production model of this sensor and performed characteristics test by applying optimum design variables. We obtained sufficient sensitivities concerning each axial load component by sensitivity evaluation of experimental results and showed the effectiveness of the developed sensor.
In order to utilize the vibration intensity (VI or structure intensity), it is necessary to clarify characteristics and usability of VI under conditions close to practical situations. The superposition of standing wave and traveling wave often occurs in actual structures. In the vibration field with a standing wave and a traveling wave, it has been reported that a curved energy flow is detected by VI unlike the case without the standing wave. It has not been validated whether the energy flow detected by VI in the case with standing wave is equal to the real energy flow. VI detects the transmission component of vibration energy. However, the standing wave is non transmission component. The influence of the standing wave on VI is still unclear. In this study, a thin plate model with a standing wave and a traveling wave was employed, and we investigated the influence of superposition of these waves on VI using finite element method (FEM) analysis. The usability of VI under this condition was evaluated. Main findings are as follows: The extra terms appear in the VI formula when the superposition of multiple waves occurs. The difference between VI with standing wave and that without it is generated by these terms. VI approximately detects real energy flows when amplitude ratio of traveling wave to standing wave is greater than five.
Vibration test is a method to verify the design of space hardware, which will endure the flight vibration environment. The problem of vibration test is over testing in comparison to the flight environment due to the mounting impedance differences in flight versus test. Force limited vibration test is the one of the popular approach to prevent the unnecessary over testing of space hardware. In this study, we propose a method to estimate the maximum interface force, which is the limit value of vibration test, of flight configuration based on the measurement FRF (Frequency Response Function) of the test hardware by simple experiment, such as impact hammer excitation. The theoretical background is described as well as discussion of experimental process, deviation sources depending on excitation location, are stated in this report.