The purpose of this study is to observe TBAB hydrate crystals growing on a cooling surface, and to reveal the effect of initial aqueous solution concentration and degree of supercooling on crystal shape and growth rate．From the observation, we confirmed that the crystal shape of TBAB hydrate differed depending on the initial aqueous solution concentration and the degree of supercooling. Additionally, we confirmed that the growth rate did not change significantly with the initial aqueous solution concentration and was almost proportional to the power of the degree of supercooling.
When electromagnetic motors are used as actuators for robots, the reduction gear is an essential component in most cases. The mechanical design choices increase if we can fabricate the custom-made reduction gear. The performance of the robot also increases because of the optimized reduction ratio. Moreover, the rapid progress of the 3D printing technology allows us to develop the reduction gear at a low cost agilely. However, most of the previous development remains at the proof-of-concept level, and quantitative evaluation of the 3D printed reduction gear is insufficient. In this paper, we fabricated a quasi-direct-drive actuator with a 3D-printed planetary gear reducer. The planetary gear reducer consists of resin molded parts by Fused Filament fabrication. We quantitatively measured its performances such as 1) transmission efficiency of static torque, 2) joint stiffness, 3) the effect of temperature on stiffness, 4) the influence of the 3D printing parameters on stiffness and strength, and 5) durability against a continuous operation. The prototype actuator unit demonstrated a sinusoidal joint movement for 46 hours, where its maximum output torque and frequency were 19.6 Nm and 0.1 Hz, respectively.
Today, the demand for industrial robots continues to grow. In order for industrial robots to make further progress, they need to reduce costs. One way to achieve this is to adapt new materials to robots in order to reduce power consumption by reducing weight. In order to realize the use of resin materials for FDM 3D printers as these new materials, we evaluate the characteristics of these materials when used. In this paper, we describe the contents and results of the evaluation of a planetary gear mechanism made with parts formed by an FDM 3D printer for the drive unit.
In this study, we investigate the applicability of the plastic parts made by FDM 3D printer to a trocoid gear reducer, which is expected to reduce the weight. A trochoidal gear reducer with a reduction ratio of 30 was developed. The part was developed using a resin material with excellent mechanical strength, nylon resin reinforced with carbon short fibers and potassium titanate, respectively, and compared with Extra Super Duralumin (A7075). The gear reducer’s outer diameter is 58 mm, height is 50 mm, and a maximum torque is about 5 Nm, mass is 205 g, 204 g, and 309 g, respectively. It is found that the efficiency of the reduction gear decreased under operating conditions due to the slipperiness of the material and the molding accuracy of the contact surface between the teeth, and that the maximum torque could be increased to more than 5 Nm by applying grease.
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