In order to increase the shearing strength and reduce the protrusion height of the clinched joint, a two-step clinching process was designed and investigated in the study. A clinching machine produced by Express Company and extensible dies were used to produce the clinched joint, while a flat die and a bumped die were used to produce the two-step clinched joint. A 2D model in the software DEFORM-2D was applied to analyze the material flow and effective stress distribution of the two-step clinched joint. To validate the numerical model, experimental tests were carried out to get the main geometrical parameters of the two-step clinched joint. The two-step clinching method could increase the neck thickness with the decrease of the protrusion height. Shearing tests were carried out to obtain the shearing strengths of the two-step clinched joints. The results showed that the shearing strength and energy absorption of the joint could be increased by the two-step clinching process because of the increased neck thickness. The two-step clinching method was proved to be effective for increasing the shearing strength and energy absorption of the clinched joint.
The 3D pen is a tool that can output a melted resin from a pen tip to form a 3D object. In order to shape an object using a 3D pen, it is necessary to practice it and understand how to use it, and many beginners find it difficult to handle. Most of the difficulty is caused by users not understanding the appropriate moving speed. On the other hand, it is necessary to have interactivity in the learning system. In 3D object drawing learning, a learning system using VR/AR capable of displaying three dimensions is desired. In this research, we aim to support learning in 3D object drawing, and proposed and developed a 3D object drawing learning support system with interactivity. Furthermore, the influence of the proposed system and a video learning system on 3D object drawing skill by 3D pen is examined. As the results of the experiments, it was necessary to practice 3D drawing with 3D pen, and it was deduced that interactive learning may be more effective than non-interactive learning after practicing 3D pen. In addition, it was suggested that interactive learning is more likely to make feel that learners improved with respect to speed and drawing related to pen. In 3D pen drawing learning, it was suggested that those who are not good at 3D drawing are more likely to feel that interactive learning has improved their drawing techniques.
In order to machine complicated workpiece shapes, it is essential for operators to avoid detrimental collisions between machine structures and workpieces. Therefore, a machine simulator based on 3D models is usually utilized prior to machining operations to ensure this problem is avoided. On the other hand, a multifunctional machine tool with both machining and additive manufacturing (AM) functions is recently developed to realize high flexibility and productivity. However, it is difficult to predict and control workpiece shapes created by AM. Such shapes are generally different from the 3D model prepared in advance. The differences may happen unexpected collisions on a multifunctional machine tool. Additionally, machining productivity may decrease when a NC program is generated with an original 3D model that is different from the actual workpiece shape. Thus, this study aims to realize highly efficient machining of complicated workpiece shapes corresponding to actual workpiece shapes as created by AM. In order to eliminate differences between the 3D model and the actual workpiece shape, a 3D model is firstly created by measuring the shape and position of the workpiece on a multi-functional machine tool. Then, appropriate position and orientation of the target shape is decided to minimize tool path distance. From results of a case study, it is appeared that the proposed machining procedure can improve machining efficiency of complicated workpieces as created by AM.
In steel continuous casting system, tundish upper nozzle has an important role on the flow rate control of the molten steel and the elimination of the inclusions and etc. Based on the basic principle of hydrodynamics, the optimal nozzle bore profile was determined with aiming to suppress the turbulence with high kinetic energy generated in the flow of the molten steel. A simulation by flow analysis and a water model experiment were performed and clarified that the turbulence with high kinetic energy could be minimized in the nozzle with newly devised inner bore profile. The actual nozzle devised was manufactured and tested in the steel works with satisfying results. It can contribute to not only improve the durability of the refractories as materials of the nozzle but also stabilize the casting operation by preventing from clogging of the nozzle.
A new geometrical design of the port in the flow line direction to minimize the maximum port velocity (MPV) has been proposed through the analysis using computational fluid dynamics (CFD) and water model experiments to keep uniform velocity distribution of the molten steel flow throughout the outlet of ports for submerged entry nozzle (SEN) in the continuous casting system. The adhesion of the alumina inclusions to the port part of the SEN is reduced by lowering the turbulent kinetic energy since the energy loss is minimized at the part. Both stability in the operation and quality of the steels have been brought by the present development.
We discuss an approach to represent product functions mathematically and derive functional equations as a means to improve product design efficiency. Product design proceeds in a set order: clarification of task and target, concept design, entity design, and detailed design. Concept design belongs to the upstream stage of product design, and consists of procedures to develop the functional structure of the product and create design solutions to realize that functional structure. Many of today’s products are complicated, large-scale systems that combine subsystems from different technology fields. The functional structures of these products are typically developed and design solutions created in concept design. Subsystem engineers then iteratively adjust subsystem design parameters in entity design and detailed design. Finally, efforts are made to realize the function and performance of the product. In the process, the design can change significantly in entity design and detailed design, and there is often a remand in concept design. By formulating product functions mathematically and evaluating the stability and the degree to which the target is achieved, we can predict product optimality in the upstream stage of product design. In this way, the likelihood of redesign in the midstream and downstream stage of product design or of returning to the upstream stage of product design will be reduced. In the design and manufacturing field, the concept of product function has a number of variations. After examining the various alternatives, we focus on generic function of quality engineering as most suitable for formulating product functions and use it to develop our approach, applying it to a combined system composed of different technical fields. We then confirm that the approach is effective in improving product design efficiency.
Defects may occur when manufacturing plastic products by injection molding if the injection conditions are not appropriate. Thus, it is extremely difficult to produce products with high-dimensional accuracy and low defects. In addition, injection conditions are determined by experience including trial and error which may involve significant time and costs. This is because the relationship between each injection condition and forming defect is not clear. Injection conditions are interdependent; thus, it is difficult to obtain a quantitative correlation with respect to the forming defects. This study proposes a method to automatically recognize forming defects and determine injection conditions to mold non-defective products, thereby creating a basic system. Focusing on shape defects such as burrs, short shots, uneven color, weld lines, and transfer defects, the system photographs the formed product with a camera, recognizes the forming defects by image data processing, and digitizes the forming state. Then, it determines the appropriate injection conditions based on digitized forming states using a neural network. The usefulness of the proposed method is confirmed through experiments conducted under the injection conditions determined by the proposed method, and optimum injection conditions were determined.
A novel design of an animal bed, which is termed “head positioner”, for fixing a rat is newly proposed in this research. The head positioner is used for a basic medical study to analyze brain activities for small animals with MRI (Magnetic resonance imaging). Various requests and specifications for it is described by investigations and our preliminary experiments in advance. A rat’s head positioner is designed by a 3D CAD (Computer Aided Design) and also created by a 3D printer with using PLA (polylactic acid) resin. An MRI experiment is performed by the new head positioner and a lot of sharp images can be taken by reducing a rat’s head motions. The images of the rat’s brain data can be also taken with the same angle as a brain Atlas which combine geometric positions with brain functions in a form of geography. It enables us to analyze the rat’s reaction from the viewpoints of the brain functions. A feasibility of the new design of rat’s head positioner is demonstrated in this paper.