Mitsugu Motomura

Computer-aided die design for axis-symmetric cold forging products by feature elimination

Abstract The authors consider forging to be a procedure for adding features to a raw material, and process planning to be the inverse procedure. Each step of the forging process is thought of as a combination of feature eliminating processes. Depending on the above, the authors have developed a CAD system to design forging sequences and die profiles. The system designs the forging sequences and die profiles from the product to its raw material by eliminating features, which is the inverse of forging processes. First, the system detects features from a product’s shape. A shape is represented by its cross-section including the axis with free curves. Its outline is described as successive finite vectors. The system extracts features by using the change of the vector direction. Second, the system searches a database of “manufacturing cases” using features such as search keys to find a candidate case in which the manufacturing process can be applied to the product. A manufacturing case is a data set having three kinds of data; search key, validity checking procedure of itself, and eliminating the procedure to get a partial preform after the elimination of the feature. Search key is the name of the feature to which a case can be applied. If the system finds a matched case by using the search key, it applies a validity checking procedure described in the matched case data. Please note that, by only eliminating features it is not possible to obtained a process plan. Each case must represent an actual forging method by which the feature can be manufactured. The validity checking procedure ensures that the eliminating process is actually to be realized as the inverse of forging. The system checks if the case can be applied on the feature or not by the validity checking procedure. If it passes, it eliminates the feature by the eliminating procedure described in the case. The procedures in each case are independent, but they exchange information about the cases and dimensions by using a working memory like a blackboard. Using the working memory, the system combines eliminating procedures automatically to get an actual manufacturing process. Thus, the system designs one forging process and preform, and after then, it also does the internal profiles of dies and exports them as point line into general purpose CAD systems. Repeating the above procedures, the system generates process plans and die profile design from the product’s shape to its raw materials. Multiple plans and profiles are designed by repeating the procedure recursively.

Expert system of cold forging defects using risk analysis tree network with fuzzy language

Abstract The authors have developed an expert system for detecting the risk of forging defects and their causes in cold processes. The system employs risk analysis for a computer-aided process planning system. In addition, the authors investigated topics that affect typical forging defects. Based on the investigation, the authors developed risk analysis tree networks to evaluate the risk potential and describe the risk potential by fuzzy language [G. J. Schmucker, Translated to Japanese by T. Onizawa, Fuzzy Set, Natural Language and Risk Analysis, Keigaku-Shuppan (in Japanese)]. The risk analysis tree networks are developed for each kind of typical defect and the location on the forging part at which they occur. The risk analysis network is a hierarchic network, and its nodes represent the topics that affect forging defects. The value of the node represents the “risk” (e.g., the “certainty the topic comes true”). First, the computer-aided process planning system uses rules in its knowledge base and the result of FE analysis for the estimation. Second, the risk rate of the upper node is determined by the average rates of its daughter nodes with weight values. Thus, the risk that a certain defect occurs at a certain location is estimated through executing the above procedure from the bottom to the top. Finally, the expert system displays the nodes that have higher risk values. They are considered the main causes of defects. The system can rapidly indicate rough but appropriate causes and the location of forging defects.

Tool life prediction for cup shaped cold forgings with fuzzy language risk analysis and fuzzy inference

Abstract A method of Die-life prediction is suggested for cup shaped forgings.Authors theorize that forge specialists can make die-life prediction by comparing a “target” forging process” with other standard processor whose actual life are known. The authors make comparison by calculation of risk (that which shortens die-life span). Risk is estimated by using a risk tree network, based on information compiled from a survey of forge experts. The risk rate of an “end node” is estimated by a computer-aided forging process planning system. Comparing dimensions of the target and standard forging processes has effect on the risk rate. Once risk is determined, it is used to predict dielife span using Fuzzy inference. The Fuzzy inference rule is estimated based on data received from the interview of experts.

Production Magnesium Alloy Strip with Boss and Rib Section by Melt Drag Process and Experimental Conditions

This study aims to produce magnesium alloy strip with boss and rib directly from molten metal. Magnesium alloy is the lightest structural material, so it is expected to widely use for small electronic device and etc. We studied about melt drag process. Melt drag process is one of single roll strip casting process. We use model melt drag experimental device to produce rapid solidified magnesium strip with boss and rib. Substrate is used on model experimental device instead of roll to easily research shape of substrate. Diameter of boss is 5 mm, 7.5 mm and 10 mm. Height of boss is 6 mm. We revealed on this study that the experimental conditions to get good shape boss and rib, improvement substrate shape for good boss and rib, microstructure and etc.

Producing Aluminum Foam Sandwich Panel by Melt Drag Process

Aluminum foam is porous material and it is superior property which is light weight , absorption sound, heat insulation and energy absorption than other materials. In present the panel of aluminum foam sandwich panel to use as structural materials is adhered with adhesive or wax for adhesion. The aim of this study is to clarify producing conditions to make sandwich panel by melt drag process. Melt drag process is single roll strip casting process. Producing aluminum alloy strip and adhering foam are at a time.

Improvement of Surface Roughness of Al-Si Alloy Cast Strip by Vertical Melt Drag Process

Strip casting process is possible to shorten for producing strip. Strip is produced from molten metal continuously and directly by strip casting process. Melt drag process is one of the single roll strip casting process. Melt drag process is simpler than general twin roll strip casting process. One of defect of cast strip is surface conditions, for example surface roughness. Cast strip surface roughness is larger than hot rolled strip. Large strip surface roughness is negative effect for cold rolling after strip casting or hot rolling. The aim of this study is improvement of cast strip surface roughness by melt drag process. We suggested vertical melt drag process. And investigations were operated such us producing conditions of Al-Si alloy strip, surface roughness of cast strip and microstructures.

Computer-aided blanking sequence design of extruded aluminum materials

Abstract Extruded aluminum alloys are presently used for building materials. We developed an expert system for blanking process planning for these three-dimensional materials using feature elimination. We consider that blanking adds features to a raw material and process planning eliminates features from a product. We attempted to implement a feature elimination procedure on computers. The shape model of the product consists of two parts, the basic material model and features. The basic material model represents the shape of a raw extruded material. It is a plain surface model made of polygonal faces. Feature models are also surface models. However, they describe a negative volume that represents the blanked parts of the product. The system chooses one face of the basic material model at the beginning of process planning, and collects the features’ faces on it. It searches a database, which we call the “processing case-base”, for each feature and finds the blanking procedure that can eliminate or create it. Repeating the above from the product to its raw material, the system develops process plans for blanking of the product.

A NEW PROCESS FOR MAKING EQUILATERAL TRIANGULAR SHAPED PRODUCTS BY LATERAL EXTRUSION

Lateral extrusion is a method for making “disc” shaped products. The extrusion press includes a billet chamber, a ram adapted to drive a billet through the billet chamber and a mandrel for making an axial flow of metal change to radial direction. This research is about new unique extrusion process, which is based on lateral extrusion. The equilateral triangular shaped products is deformed from cylindrical billet by using this new lateral extrusion method. In lateral extrusion, a billet is extruded radially by a mandrel. As the extrusion progresses, the diameter of produced disc increases. But, when the extrusion has progressed further, the produced disc breaks at its circumference because of a tensile force. In the new method, the disc is forced to break before maximum diameter by the grooves on the mandrel. To break the disc, the grooves patterned on the mandrel, which look like veins of leaf, are used. The grooves is designed to make the metal flow easily toward corners and to force the flow to side wards. Using this method, it is attempted to produce the triangular shaped products through a process of only one step.

Effects of forming factors on production of wide clad aluminum alloy foils by single roll rapid solidification.

Production of rapidly solidified aluminum alloy clad foils with 160mm width were attempted by use of a single roll apparatus with tandem nozzles, controlling some forming factors, ie. roll speed, thickness and width of the base foil and overlying foil, order of ejection of molten alloys from two nozzles, distance between nozzles, combination of alloys for base and overlying foils. When roll speed is low or distance between nozzles is not suitable, there are cracks and disturbed layer at interface between base and overlying foils. Sound clad foil is achieved by decreasing width and thickness of overlying foils less than those of base foils. Materials and surface condition of base foils affect the surface condition of overlying foils. Combinations of alloys for base and overlying foils affect formation of crinkles of clad foil.

Deformation and forging load in axisymmetric free shape hot forging of 1100 aluminum.

A free shape forging process is proposed to make products in different shapes and dimensions by one set of dies and its deformation and load characteristics are investigated in case of applying this process to an axisymmetric hot forging of aluminum. The distinctive feature of this process is that the die configuration is composed of punches applying loads to a specimen individually. In this experiment, the lower die had a rectangular shape in the cross section and the upper die set was composed of three punches of the shapes of two concentric rings and one cylinder, each of which could independently apply a quasi-static load to a specimen. Dimensions of specimen and load were measured during forging, and the maximum load was compared with that of a conventional process. This process of one set of dies has been shown to be able to forge various shapes, and the effect of control procedures of the punches on the deformation pattern is discussed. The maximum load of this process is smaller than that of the compared process. This free shape forging process has been demonstrated to be suitable for making products in various shapes in small quantities.