首页期刊导航|International Journal of Precision Engineering and Manufacturing
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International Journal of Precision Engineering and Manufacturing
Springer Verlag
International Journal of Precision Engineering and Manufacturing

Springer Verlag

2234-7593

International Journal of Precision Engineering and Manufacturing/Journal International Journal of Precision Engineering and ManufacturingEIISTPSCI
正式出版
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    Kerosene Supply Effect on Performance of Aluminum Nitride Micro-Electrical Discharge Machining

    Kim, DaenyoungKim, Yoo-SeokSong, Ki YoungAhn, Sung Hoon...
    11页
    查看更多>>摘要：As interest in aluminum nitride (AlN), a high-performance ceramic, has been rapidly increasing, many researchers studied the possibilities of machining it. Since AlN is classified as a difficult-to-cut material, the electrical discharge machining (EDM) process using an assisting electrode is emerging as an effective machining method. Kerosene, as a dielectric fluid, plays an important role in forming a successive conductive carbon layer on the surface of the workpiece to induce and maintain discharge. Most previous methods used tubular electrodes to stably feed the dielectric fluids through their center hole. However, in the case of micro-EDM, the extremely small electrode diameter makes it difficult to fabricate a through-hole in the electrode, and a very narrow gap prevents the flow of dielectric fluid. In order to overcome dielectric fluid flow problems in micro-EDM, in this study, two kinds of flow-promoting methods are introduced: one is to use a D-shaped solid electrode to obtain a wider asymmetric flow channel, and the other is to use an O-shaped solid electrode with graphite-powder-mixed kerosene (GPMK) under a relatively wider discharge gap. Flow simulation results show that both methods promote kerosene flow, and the experimental results show similar results as well. When using the D-shaped section, the material removal rate increased, but increased tool wear was observed. In the case of GPMK, the metal removal rate increased 64%, and relative wear ratio decreased 73% compared to conventional methods. Through voltage scheduling, the problem of precision degradation that occurs during deep-hole drilling with the O-shaped solid electrode GPMK configuration was solved without sacrificing machinability.
      原文链接:
    • NSTL
    • Korean Soc Precision Eng

    A Numerical Approach for Predicting the Springback of Intersecting High-Stiffened Integral Panel in Spherical Die Forming

    He, QiyuanLi, WeidongWan, MinLi, Cailing...
    16页
    查看更多>>摘要：Taking advantage of the high specific strength, structural efficiency, and rigidity of spherical multi-intersecting high-stiffened integral panels, they have been used on a manned space station as the main load-bearing structure. Due to their large size and complex structure, a new incremental die forming approach was proposed, where the panel is pressed by a relatively small die at devised positions multiple times in proper order. However, the springback behavior of the panel after each depression is extremely complicated due to the interactions between multi-intersecting ribs. In this paper, a numerical approach of springback prediction for a typical intersecting stiffened panel in spherical die forming was proposed and the corresponding algorithm was developed. The approach quantifies the influence between multi-intersecting ribs by a novel definition of a bending neutral layer on the panel: the 3-D springback of whole panel is equivalent to the 2-D springback of the ribs. The strain component led by skin deformation and its elastic release are considered. A plasticity model with a nonlinear strain hardening of material was adopted. The approach was employed to predict the springback of panels with different forming radii, different rib sizes, and local large-rigidity structures. A rapid springback compensation based on the approach was achieved. The calculated results are in strong agreement with the results of FEM simulations based on ABAQUS software and experiments, accurately predicting profiles error within 2 mm.
      原文链接:
    • NSTL
    • Korean Soc Precision Eng

    Identifying Abnormal CFRP Holes Using Both Unsupervised and Supervised Learning Techniques on In-Process Force, Current, and Vibration Signals

    Kim, DaveShin, KangwooKim, Hyo-YoungLee, Seok-Woo...
    17页
    查看更多>>摘要：This study aims to conduct abnormality detection by applying machine learning algorithms when drilling a carbon fiber reinforced plastic laminate. In-process signals including current, thrust force, and vibration were captured during the dry drilling experiments using a 6 mm physical vapor deposit diamond-coated drill at the consistent spindle speed of 6500 RPM and 0.05 mm/rev. Across measurements from out-of-process variables, including hole diameter, roundness, surface roughness, entry/exit delamination, and entry/exit uncut fiber area, in-process measurements were most able to find outliers with respect to diameter. Both Principal Component Analysis, an unsupervised dimensionality reduction technique, and Linear Discriminant Analysis, a supervised dimensionality reduction technique, could separate oversize or undersize holes from average-sized holes when using fast Fourier transformation data of in-process vibration. Predictive performance with k-Nearest Neighbors shows that our machine learning pipeline can predict oversized vs. non-oversized holes with over 85% accuracy in this dataset. Peak prediction performance is obtained when in-process measurement data is viewed from the frequency domain, and predictions are weighted based on the relative distances of the nearest neighbors.
      原文链接:
    • NSTL
    • Korean Soc Precision Eng

    Error Compensation Through Analysis of Force and Deformation in Non-circular Grinding

    Jang, JoonChoi, Woo Chun
    12页
    查看更多>>摘要：With industrial advancement, the demand for precision parts is increasing. A crankshaft is the main part of an engine, which determines the life and quality of the engine, and is one of the precision parts whose demand is growing. Non-circular grinding is the grinding method used for crankshafts, and it is different from conventional grinding methods. In this study, the grinding force, considering the characteristics of the non-circular grinding, was obtained, and the bending and torsional deformation of the crankshaft caused by the grinding force was predicted. By applying the deformation to the grinding force, a real depth of the cut prediction model that can calculate the grinding force and predict the real depth of cut was proposed. A compensation model that can estimate the set depth of cut was proposed to obtain the desired real depth of cut. Various grinding characteristics related to force and deformation in non-circular grinding were analyzed. It was observed that the grinding force has different values at all grinding points, even if one pin is ground because the change in the workpiece velocity depends on the grinding point. Unlike in general grinding, the tangential force affects the depth of cut. The real depth of cut obtained through the prediction model proposed in this study differed from the set depth of cut by up to 45%. Comparing the compensation model of this study to the conventional method, the former showed approximately 20% improved compensation performance.
      原文链接:
    • NSTL
    • Korean Soc Precision Eng

    Optimization for Whole Body Reaching Motion Without Singularity

    Jeong, HyobinLee, Inho
    13页
    查看更多>>摘要：This paper presents an algorithm optimizing the whole-body reaching motion of the humanoid robot. After the humanoid robot reaching to the target object, the robot will perform a task such as lifting up the object, opening the door, closing the valve, etc. In order to perform such tasks, the arm configuration space of the robot should not be in the singular configuration that the robot loses its ability to move the end-effector in some direction no matter how it moves its joints. Hence, the robot should generate reaching motion without singularity for a given target point. To yield a solution for this issue, we divided singular cases into two cases through the Jacobian analysis for the 7 DOF arm of our humanoid robot which of the wrist joint has a spherical joint structure that three joint axes intersect one point. By means of self-motion of the redundant arm, one is able to escape is defined as 'escapable singularity' and the contrary is defined as 'inescapable singularity'. The escapable singularity is addressed by the proposed low computing singularity avoidance control. Since the inescapable singularity cannot be avoided by self-motion, the proposed approach used pelvis motion to control shoulder position itself which is the base frame of the arm. To optimize the pelvis motion, we formulate a minimization problem for a simple kinematic model representing pelvis motion with newly defined a geometric constraint. The geometric constraint is selected by the result of the Monte Carlo method for four upper joints because the inescapable singularity is occurred by the four upper joints space only. To demonstrate the feasibility of the proposed optimization, the randomly stacked debris is put in front of the humanoid robot, and the robot would reach the debris.
      原文链接:
    • NSTL
    • Korean Soc Precision Eng

    User Intention Based Intuitive Mobile Platform Control: Application to a Patient Transfer Robot

    Park, JaewooAn, BohyunKwon, OhwonYi, Hak...
    14页
    查看更多>>摘要：This study proposes a user's intuitive intention-based control system for mobile robot platforms. As an application of the control scheme, we focused on a robot that transports patients in medical facilities. However, since most of the people who operate the patient transfer robot (PTR) are not robotics experts, an intuitive control method is needed to enable easy operation of the robot system. Also minimizing the discomfort experienced by the patient in the process of transferring the patient through the patient transfer robot is another important issue to consider. Therefore, the main contributions of this are developing an intuitive user interface and proposing a sway reduction control scheme. To accomplish the first issue, the intuitive control is implemented by proposing a robot control interface, where four force-sensing resistor (FSR) sensors are installed on a robot's handle (where a user holds a robot). Through this, the robot can be easily moved with only a simple and intuitive operation of the user. Therefore forward, backward, left movement, right movement, left turn, and right turn operation can be controlled through the intuitive movement of the user input through the developed user interface. Additionally, in order to satisfy the second requirement, the patient's sway reduction strategy is suggested by applying fuzzy logic-based control command generation method to the user intention. Through this method, the sway that occurs during the movement of the robot is reduced. In this study, the mecanum wheel was applied to the driving platform of the patient transfer robot to enable omnidirectional movement. The performance of the proposed control method is verified through simulations and experiments. Simulation and experimental results confirm that the proposed method reduced the acceleration and jerk root mean square values of the robot compared to a comparison method.
      原文链接:
    • NSTL
    • Korean Soc Precision Eng

    A Study on Tool Breakage Detection During Milling Process Using LSTM-Autoencoder and Gaussian Mixture Model

    Nam, Jun SikKwon, Won Tae
    9页
    查看更多>>摘要：In the milling process, a rotating cutting tool is used to cut the raw material into the desired shape. Since tool breakage adversely affects productivity, real-time tool breakage detection is required. In this study, a tool breakage monitoring system using AE signals and a deep learning model was investigated. First, LSTM-Autoencoder was constructed and trained using the AE signal, cutting speed, spindle speed, and depth of cut as input data. In order to distinguish between tool normality and anomalies, the largest value among the normal cutting data set was determined as the threshold to determine if the tool was broken. As the result of the experiment, we obtained the accuracy of 82.1% during normal cutting, but the accuracy was significantly reduced to 63.1% and 63.6% at the time of entry/exit. This is because the AE value that occurs during normal entry/exit is so large that it is mistaken for breakage. To overcome this problem, a combined model that uses both LSTM-Autoencoder and Gaussian Mixture Model was developed. First LSTM-Autoencoder was used to determine the breakage, and then Gaussian Mixture Model was used to determine the authenticity of the breakage. As a result of the experiment using the developed model, 52 out of 57 cuttings including entry/exit cutting were detected as failures, showing a high reliability of 91.2%, proving the superiority of the combined model.
      原文链接:
    • NSTL
    • Korean Soc Precision Eng

    Contact Load and Stiffness of Four-Point Contact Ball Bearings Under Loading

    Rivera, GilbertVan-Canh TongHong, Seong-Wook
    11页
    查看更多>>摘要：Four-point contact ball bearings (X-ACBBs) are highly effective in applications requiring support for shafts that feature a high ratio of diameter to unsupported axial length and axial loading in two directions. In an effort to predict and understand problems that have been reported in X-ACCB usage, new modeling and analysis of the contact load and stiffness of X-ACBBs has been presented. The new model features a quasi-static model for X-ACBBs subjected to five degrees-of-freedom loading and displacement. The model was validated against numerical ball contact loads available in the literature. A numerical investigation was then performed to study the effects on ball contact loads and stiffness of rotational speed, external loads, and various geometric parameters of bearings such as arching dimension and unloaded contact angle. Under pure axial load, increasing the rotational speed causes an abrupt change in X-ACBB stiffness when the ball contact changes from two-point to three-point contact. Gyroscopic moment reduces the speed at which transition from two-point to three-point contact occurs. The dependence of X-ACBB stiffness on arching dimension and unloaded contact angle reveals that those parameters are critical for the design of X-ACBBs.
      原文链接:
    • NSTL
    • Korean Soc Precision Eng

    Influence of Thermal Processing Conditions on Mechanical and Material Properties of 3D Printed Thin-Structures Using PEEK Material

    Li, GuiweiQu, HanZhang, WeiWu, Wenzheng...
    11页
    查看更多>>摘要：Poly-ether-ether-ketone (PEEK) was one of the most promising engineering plastics, which had been widely employed in the aerospace, biomedical and automotive industry and manufacturing. The design of various 3D printing (3DP) parameters had a significant impact on its mechanical and thermal properties. This study aimed to investigate the thermodynamic properties of thin-structure PEEK samples by printing them under various conditions, including varying substrate and ambient temperature parameters, under a control- method. Numerous critical properties such as interlayer bonding force, tensile and bending properties, dynamic mechanical properties, and crystallization had been investigated in this work. The results indicated that the maximum relative interlayer bonding force was 989.91 N, while comparing to the lowest initial ambient and substrate temperature 60 degrees C and 90 degrees C, the optimal tensile and bending strengths both increased by 28.46% and 13.86% to 86.62 MPa and 113.21 MPa under ambient and substrate temperature 90 degrees C and 160 degrees C, respectively. Concurrently, the crystallinity increased by 6.67% to 31.56%. Mechanical and thermal properties had been significantly improved when appropriate substrate temperature parameters were used during the printing process, demonstrating the enormous potential in printing PEEK material. Thermal processing was another critical factor in achieving higher performance of 3D printing PEEK components.
      原文链接:
    • NSTL
    • Korean Soc Precision Eng

    A Dual Difference Method for Identification of the Inherent Spindle Axis Parallelism Errors of Machine Tools

    Yang, Seung-HanLee, Kwang-Il
    10页
    查看更多>>摘要：It is essential to identify spindle axis parallelism errors because such errors trigger volumetric errors when tools of different lengths are used. However, only a few works have addressed this issue. Thus, we identified the inherent spindle axis parallelism errors of machine tools relative to the end-point reference straight line of the Z-axis (according to ISO 230-1) using a dual difference method. Here, "inherent" refers to parallelism errors of the spindle axis that are not affected by the geometric errors of other axes controlled during the measurements, and "dual difference" refers to the difference in the differences of measuring data. The dual difference method uses two pairs of circular tests performed with the aid of a double ball-bar (DBB); the tool lengths differ during each test and the DBB set-up is shared by the pairs. Parallelism errors are then identified based on the dual differences within and between the two pairs. Experimentally, the maximum peak-to-valley (PV) values were 54.5 and 48.7 mu m for differences in radial deviations within the two pairs when the parallelism errors were not compensated. After tool-center-point compensation by the identified errors, the PV values improved to 8.0 and 9.2 mu m, respectively, showing that compensation was successful. In addition, the concentricity of two holes machined using tools of different lengths improved from 31.2 mu m without compensation to 15.9 mu m with compensation, further demonstrating the effectiveness of the method.
      原文链接:
    • NSTL
    • Korean Soc Precision Eng