Bearing-shaft systems are essential components in various automated manufacturing processes, primarily designed for the efficient rotation of a main shaft by a motor. Accurate fault detection is critical for operating manufacturing processes, yet challenges remain in sensor selection and optimization regarding types, locations, and positioning. Sound signals present a viable solution for fault detection, as microphones can capture mechanical sounds from remote locations and have been traditionally employed for monitoring machine health. However, recordings in real industrial environments always contain non-negligible ambient noise, which hampers effective fault detection. Utilizing a high-performance microphone for noise cancellation can be cost-prohibitive and impractical in actual manufacturing sites, therefore to address these challenges, we proposed a convolution neural network-based methodology for fault detection that analyzes the mechanical sounds generated from the bearing-shaft system in the form of Log-mel spectrograms. To mitigate the impact of environmental noise in recordings made with commercial microphones, we also developed a denoising autoencoder that operates without requiring any expert knowledge of the system. The proposed DAE-CNN model demonstrates high performance in fault detection regardless of whether environmental noise is included(98.1%) or not(100%). It indicates that the proposed methodology effectively preserves significant signal features while overcoming the negative influence of ambient noise present in the collected datasets in both fault detection and fault type classification.

To efficiently develop an automatic assembly system that can enhance the quality and assembly productivity of the shaft assembly in EV relays, a DMU model was utilized. After modeling each component of the assembly system using the CAD software CATIA, a DMU model of the assembly cells and the entire assembly system was created using the assembly model. Additionally, the DMU Kinematics Workbench was employed to verify and validate the design of the automatic assembly system for the shaft assembly, a key component of the EV relay, before actual construction. This approach helped reduce time and costs by minimizing trial and error.

The intermediate shaft of sliding type is assembled with coated shaft joint and tube joint. Since the intermediate shaft plays a role of absorbing displacement change due to vibration, the intermediate shaft must have a sliding force value in an appropriate range. In this study, an intermediate shaft assembly system for post-processing of defective intermediate shafts was developed. The intermediate shaft assembly system consists of a wear count prediction model and an automatic wear system. A wear count prediction model was created with the initial assembly sliding force, quality, and set values. As a result of applying the intermediate shaft assembly device, the sliding force of the intermediate shaft was induced within the set value range. And it was prevented from the intermediate shaft defect and eliminated manual work.

본 논문에서는 1차원 오일러 보 요소(Euler-Bernoulli Beam Element)를 이용한 회전익기 축계에 대한 중량 최적설계를 수행하였다. 회전 축계의 특성을 고려해 비틀림(Torsion)과 베어링과 같은 축지지 강성 및 플랜지(Flange) 질량을 모두 고려하였고, 동적 안전성 확 보를 위해 고유치 해석을 수행하여 임계속도(Critical Speed)와 기어박스로부터 오는 치 변형 가진을 회피할 수 있도록 하였다. 축의 길 이는 고정된 상태에서 두께와 반경을 조절하여 중량 최적화를 수행하였으며, 최적화 과정은 2단계로 나누어 진행하였다. 1단계에서 는 비틀림 강도를 제약조건으로 하여 중량을 최적화한 후 2단계에서는 축계 안정성 확보 기준(Headquarters, U.S. Army Material Command, 1974)에 따라 축의 비틀림 강도에 대한 제약조건을 만족시키며, 축의 1차 모드가 임계속도를 회피할 수 있도록 축 1차모드 와 임계속도의 차이가 최대가 되도록 최적화를 진행하였다. 주어진 1차원 보 요소를 이용하여 최적설계를 한 결과를 3차원 유한요소 모델과 실제 제작된 축게의 시험결과와 비교하여 제안된 방법을 검증하였다.

This paper has been carried out the forming analysis, die stress analysis, and relevant tests for the straightness improvement of hollow shafts with blocktooth. Hollow forward extrusion is a process that a material in a die is pressed with a punch and the material is formed into the same direction through the gap of a mandrel and a bottom die. For an asymmetric shaped product, due to the difference of reduction ratios of the cross sections in its extruding, a phenomenon that the product bends from the difference of the flow speed comes to occur. As applying the key to the mandrel has a uniform flow speed, bending problem was solved. These were processed using Deform-3D as a finite-element analysis program. Analysis was compared with the experiment. Keyway height of the mandrel has been confirmed that the straightness best when it comes 0.1mm. These study are expected to be available as fundamental data in die design necessary for the manufacture of asymmetric goods in the future.

회전축계가 거동시 지진하중을 받을때의 응답 거동을 조사하였다. 지진과 기동으로 인하여 회전축계가 불안정하다면, 과다한 진동이 발생할 뿐만 이니라 회정지계의 회전자가 고정자와 부딪혀 기계 성능을 발휘하지 못하게 할 것이다. 그래서 면진장치를 갖춘 기초에 지진동이 작용할 때에, 회전축계의 응답을 모사하였다. 거동시 회전축계의 과도 응답을 얻기 위하여 우선 회전축계의 운동방정식을 유도 하였다. 유도한 운동방정식은 비선형이어서 Runge-Kutta 수치해석법을 이용하여 응답을 계산하였으며, 기동 운전모드에 따른 거동뿐만 아니라 면진스프링의 강성을 매개변수로 취하여 회전축계의 응답거동을 고찰하였다.

공동구용 수직구 접속부는 부등침하 발생, 지하수위 저감, 지진 등 동하중에 의한 상대변위 발생 등의 문제점이 야기되고 있다. 현재 국내에서는 수직구 접속부 시공 시 지반안정화를 위한 각종 공법을 적용하고 있으나, 접속부에 대해 직접적인 보강/차수 기술 적용은 전무한 실정이다. 따라서 본 연구에서는 공동구용 수직구 접속부에서 야기되고 있는 문제점을 상쇄할 수 있는 공동구용 수직구 접속부 보강/차수 장치 시제품을 개발하였다.

Shield tunnel-shaft joint has caused problems in use which has different soil condition and boundary condition according to structure type. For solving this problems we developed joint reinforcing and inflow water cut-off system which can ensure stability of shield tunnel-shaft and reduce costs of maintenance.