Kenji Shirai

An experimental study on ejection forces of injection molding

In injection molding, the ejection forces decrease when the surface roughness of mold decreases. However, the ejection forces increase contrary in the area of surface roughness is less than 0.2 μmRa. Several kinds of PVD films are coated on the mold cores to prevent the increasing of ejection forces. Some of these PVD films showed effective prevention of increasing of ejection forces.

A CAD System for Progressive Dies

A compact and practical progressive die design system is described. Progressive die design has been thought to be a matter of empirical engineering and therefore difficult to computerize. However, from an investigation of the progressive die design process and the average time required, it is found that highly empirical processes are utilized only in designing the strip layout and die layout, and that their combined times constitute at most 10 percent of the total design time.

Development of a CAD/CAM System for Progressive Dies

Summary In response to the increasing demand for press tools, a compact and practical CAD/CAM system for progressive dies, one of the most complicated types of press tools, has been developed. The features of this system are: (1) designing can be easily accomplished just by inputting the geometrical data of the strip and die layouts, and (2) CAM information can be directly extracted from the CAD information. In developing this system, a new model for die construction has been determined by studying the design process. An algorithm and data file needed for automatic tool selection and calculation of machining conditions and tool paths have been completed from the data obtained by using this model. To analyze the usefulness, many practical studies have been performed, and it has been found that the total period for design and manufacturing is reduced to about 1/5 the time previously required. This method can also be applied to many other types of press tools, such as compound dies, single dies, and transfer dies.

Manhattan-World Assumption for As-Built Modeling Industrial Plant

As industrial plants such as chemical and power plants continue to age, their CAD models are increasingly required for model-based planning and simulation. However, in the case of old plants, the original CAD models rarely exist, and hand-drawings do not precisely match the present states of the plants due to repeated remodeling. It is therefore becoming a common approach to reconstruct CAD models from the point cloud of such plants captured by terrestrial laser scanning and use these models for the above purposes. Such a reconstruction process is usually called “as-built modeling”. However, existing methods for as-built modeling come with such problems as the need for many human operations and computational cost. In this paper, we propose an automatic and efficient method for as-built modeling industrial plants using Manhattan-world assumption which states that there exist three dominant axes orthogonal to each other in artificial buildings and the internal parts are arranged so that they are parallel or orthogonal to one of them. In the case of industrial plants, it is reasonable to consider that long pipes and shaped steels are arranged so that they follow this assumption. In addition, plant parts are supposed to be designed as long linear sweep surfaces on CAD system or hand drawings. Our method can automatically recognize such sweep parts and their cross sectional shape which follow the assumption, as well as efficiently recognize them even from a large point cloud which may contain as many as one hundred million points in a few minutes. We demonstrate the effectiveness of our proposed method from various experiments on real scanned data.

Quantitative damage assessment of concrete structures based on 3D laser scanning

Recently scaling damages of concrete structures have become apparent and it is now investigated to develop a method for quantitatively assessing the damages. In this paper, we propose a beneficial method for this purpose based on long-distance 3D laser scanning. In our proposed method, original shapes of the concrete structures before to be damaged are estimated on their laser scanned data by region growing, the distances to the estimated shapes are computed at each scanned point, and then their surface concavity and convexity are quantitatively evaluated based on the computed distance. We demonstrate the effectiveness of our proposed method from various experiments on real scanned data of concrete structures with scaling damages.

Parts identification and motion estimation on CT scanned assembly meshes

Along with the recent improvements of the industrial X-ray CT scanning systems, it is now possible to non-destructively acquire the entire meshes of mechanical assemblies. This technology has the potential to realize an advanced inspection of assemblies, such as examining assembling errors or dynamic behaviors in motion using the meshes reflecting really-assembled situations. However, to realize such advance inspections, it is required to identify each part and to estimate their motions in the meshes.

Proposal of Method Estimating Deformation of Printed Characters Utilizing GA

A method is proposed for estimating deformation of printed characters. In this method, displacement, rotation, dilation/erosion, and magnification are taken to be character-deformation parameters, and character deformation is estimated by measuring changes in these deformation parameters with respect to a standard character. To measure the deformation from a standard character, the target character is deformed using a genetic algorithm, the deformed character is matched up with a standard character, and deformation parameters are determined for the best match between two characters. An experiment performed on several characters demonstrated that these deformations as well as missing and excess sections could be measured.

Rotational micromachining tool controlled by optical radiation pressure

This paper describes a new approach for micromachining using optical radiation pressure, which can not only trap and manipulate, but also rotate a dielectric particle with micrometer size. In order to verify the feasibility of our proposed micromachining, we fabricated a shuttlecock optical rotator as a rotational micromachining tool from a silica particle (5μm in diameter) by focused ion beam (FIB). Fundamental experiments were performed about the influence of focus point and laser power on the rotational properties of the machining tool. Furthermore, by traversing the rotating tool over the silicon wafer surface, it was found that the micro groove with several nm in depth could be generated.