A Novel High Speed/High Precision Ball Screw

Zhe-Zhu Xu,류성기,Xiaojing Liu,최종훈 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

As a tried and tested technology, ball screw drive systems are still used in a majority of machine tools which can meet the demands of higher productivity and tight part tolerances due to their low cost and high degree of stiffness. High speed ball screw drive system generates more heat and it results in greater positioning error, adversely affecting the accuracy of high precision machined parts. In this paper, a novel/well designed high speed/high precision nut air cooling ball screw system was developed to avoid thermal errors which affect the positioning accuracy and the temperature rise of ball screw. In order to discuss the effectiveness of the developed high speed/high precision nut air cooling ball screw system, a series of tests was done. As the results, it shows that the positioning accuracy will significantly improve with the use of the nut air cooling ball screw drive system shown in this paper.

Study on Simulation and Calculation Method of Thermal Error Compensation System for a Ball Screw Feed Drive

Zhe Zhu Xu(허철수),Chang Choi(최창),Lae-Sung Kim(김래성),Kwon-In Baek(백권인),Sung-ki Lyu(류성기) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.2

Due to the requirement of the development of the precision manufacturing industry, the accuracy of machine tools has become a key issue in this field. A critical factor that affects the accuracy of machine tools is the feed system, which is generally driven by a ball screw. Basically, to improve the performance of the feed drive system, which will be thermally extended lengthwise by continuous usage, a thermal error compensation system that is highly dependent on the feedback temperature or positioning data is employed in the machine tool system. Due to the overdependence on measuring technology, the cost of the compensation system and low productivity level are inevitable problems in the machine tool industry. This paper presents a novel feed drive thermal error compensation system method that could compensate for thermal error without positioning or temperature feedback. Regarding this thermal error compensation system, the heat generation of components, principal of compensation, thermal model, mathematic model, and calculation method are discussed. As a result, the test data confirm the correctness of the developed feed drive thermal error compensation system very well.

Study on Thermal Behavior Analysis of Nut/Shaft Air Cooling Ball Screw for High-Precision Feed Drive

Zhe-Zhu Xu,류성기,Xiaojing Liu 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.1

In a machine tool, continuous usage causes heat generation at the moving elements and this heat causes expansion of the various structural elements of the machine tool. The main direction of current research about machine tool thermal error is that named thermal error compensation. This paper presents a new approach in thermal error control instead of thermal error compensation and applied on a ball screw feed drive system. Ball screw is the key contributor to the thermal error of a machine tool which leading to dimensional error of machined work-piece. A novel/well designed high speed/high precision nut/screw air cooling ball screw system was developed to control thermal errors on a machine tool feed drive system. In order to discuss the effectiveness of the developed high speed/high precision nut/screw air cooling ball screw system, a series of tests was done. In this paper, experimental thermal behavior of nut/screw air cooling ball screw system for high-precision feed was discussed. As the results, relatively big temperature rising presented through the whole test process in no cooling condition and “Learning curve” phenomenon presented in the cooling cases. And the dominated temperature rising area covered the nut moving range completely.

Study on Modular Modeling and Performance Evaluation of a Conical Gear for Marine Transmission System

Zhe-Zhu Xu,Jun-seong Kim,김래성,Dong-Yang Li,류성기 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

Conical involute gears, which are also known as beveloid gears, are the involute gears with cone-shape gear body rather than cylindrical gear body. Generally, conical gears are used in anti-backlash transmission systems and marine transmission systems. In marine transmission system, in order to obtain optimal propulsive force, 7-14 degree inclination angle was needed. In this paper, a 7 degree cone angle conical gear used in 375 kW class marine power transmission system was selected as research objective. And in order to establish the design theory of conical gear, a design system named conical gear modular modeling system was developed. The prototype conical gear was developed by the above design system to be used to simulate in a certain condition. The simulated and optimized prototype conical gear was manufactured which is as a specimen to complete a series of performance tests which contains gear tooth profile test and contact rate test. As the results, the developed conical gear can well meet the performance requirements of the 375 kW class marine power transmission system.

Metabolism of an Insecticide Fenitrothion by <i>Cunninghamella elegans</i> ATCC36112

Zhu, Yong-Zhe,Fu, Min,Jeong, In-Hong,Kim, Jeong-Han,Zhang, Chuan-Jie American Chemical Society 2017 Journal of agricultural and food chemistry Vol.65 No.49

<P>In this study, the detailed metabolic pathways of fenitrothion (FNT), an organophosphorus insecticide by <I>Cunninghamella elegans</I>, were investigated. Approximately 81% of FNT was degraded within 5 days after treatment with concomitant accumulation of four metabolites (M1–M4). The four metabolites were separated by high-performance liquid chromatography, and their structures were identified by mass spectroscopy and/or nuclear magnetic resonance. M3 is confirmed to be an initial precursor of others and identified as fenitrothion-oxon. On the basis of their metabolic profiling, the possible metabolic pathways involved in phase I and II metabolism of FNT by <I>C. elegans</I> was proposed. We also found that <I>C. elegans</I> was able to efficiently and rapidly degrade other organophosphorus pesticides (OPs). Thus, these results will provide insight into understanding of the fungal degradation of FNT and the potential application for bioremediation of OPs. Furthermore, the ability of <I>C. elegans</I> to mimic mammalian metabolism would help us elucidate the metabolic fates of organic compounds occurring in mammalian liver cells and evaluate their toxicity and potential adverse effects.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jafcau/2017/jafcau.2017.65.issue-49/acs.jafc.7b04273/production/images/medium/jf-2017-04273g_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jf7b04273'>ACS Electronic Supporting Info</A></P>

The effect of annealing temperature on the morphology and piezoelectric characteristics of BaTiO3 nanofibers and domain switching under different temperatures

Zhe Zhu,Weiming Zhu 한국물리학회 2018 Current Applied Physics Vol.18 No.8

Effects of annealing temperature (600–750 °C) on crystalline structure, the morphology and piezoresponse hysteresis loops of BaTiO3 nanofibers prepared by electrospinning are characterized by X-ray diffraction, scanning electronic microscopy, transmission electron microscope and piezoresponse force microscope. When the annealing temperature is 700 °C, the nanofibers become smoother and have a diameter of 100–300 nm. Meanwhile the typical butterfly-shaped amplitude loop and 180°phase change represents the best ferroelectric and piezoelectric properties at 700 °C. So the 700 °C was found to be optimum for good piezoelectric characteristics at annealing temperature of 600 °C–750 °C. In order to give more clear evolution of domain states at different external fields, the three dimensional topographic and phase images of the nanofiber at different temperatures are observed by piezoresponse force microscope. The 90° domain switching is observed during heating from room temperature to 125 °C and the domain switching tends to be stable when the temperature exceeds a critical value. The thermal stress due to the high temperatures is responsible for switching mechanism from the perspective of equilibrium state free energy. This work suggests that the temperature variation should be considered while designing the ferroelectric devices based on one dimensional material.

Study on a Novel Thermal Error Compensation System for High-Precision Ball Screw Feed Drive (1st Report: Model, Calculation and Simulation)

Zhe-Zhu Xu,최창,Long-jun Liang,Dong-Yang Li,류성기 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.9

In general, in order to compensate the thermal error or the positioning error of a ball screw feed drive system, the actual temperature or positioning data feedback was needed. The traditional thermal error compensation system of ball screw feed drive is highly dependent on the feedback temperature or positioning data. Because of the overdependence to measuring technique, increasing of compensation system cost and decreasing of productivity level will be an inevitable trend in a machine tool. This paper presents a new approach in ball screw thermal error compensation system which can work without any temperature or positioning feedback. As the parts of the thermal error compensation system, component heat generation, compensation method, thermal model, mathematic model and calculation method were studied respectively. In order to verify correctness and generality of the developed thermal model and the thermal error compensation system, a series of simulations was carried out in several kinds of working condition. Through the series of simulations with the thermal model, calculation method and simulation conditions, deformation characteristics and thermal behavior of the prototype ball screw system have been obtained.

A Study on Improvement of Ball Screw System Positioning Error with Liquid-Cooling

Zhe-Zhu Xu,류성기,Xiaojing Liu,최종훈 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

The demand for higher productivity and tight part tolerances requires machine tools to have faster and more accurate feed drive systems. As tried and tested technology, ball screw drive systems are still used in a majority of machine tools due to their low cost and high degree of stiffness. A high-speed ball screw drive system generates more heat and results in greater positioning error,adversely affecting the accuracy of machined parts. In this paper, we discuss the placement of a liquid-cooling system using water,coolant oil, light oil and cutting oil as coolants in a ball screw shaft to avoid thermal errors and achieve temperature equilibrium faster. In order to estimate the positioning error and thermal distribution of the ball system and effectiveness of the liquid-cooling system, all possible heat gain-loss sources were analyzed and considered calculation factors. The following paper also presents degree of positioning error improvement when a circulation liquid-cooling system and forced liquid-cooling system were employed. When comparing the predictions and the experimental results, we can see very significant cooling performance and a high degree of consistency between prediction and reality.

MicroRNA-100 Resensitizes Resistant Chondrosarcoma Cells to Cisplatin through Direct Targeting of mTOR

Zhu, Zhe,Wang, Cun-Ping,Zhang, Yin-Feng,Nie, Lin Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.2

Chondrosarcomas are malignant cartilage-forming tumors of bone which exhibit resistance to both chemotherapy and radiation treatment. miRNAs have been well demonstrated to regulate gene expression and play essential roles in a variety of biological processes, including proliferation, differentiation, migration, cell cycling and apoptosis. In this study, we obtained evidence that miR-100 acts as a tumor suppressor in human chondrosarcomas. Interestingly, cisplatin resistant chondrosarcoma cells exhibit decreased expression of miR-100 compared with parental cells. In addition, we identified mTOR as a direct target of miR-100. Overexpression of miR-100 complementary pairs to the 3' untranslated region (UTR) of mTOR, resulted in sensitization of cisplatin resistant cells to cisplatin. Moreover, recovery of the mTOR pathway by overexpression of S6K desensitized the chondrosarcoma cells to cisplatin, suggesting the miR-100-mediated sensitization to cisplatin dependent on inhibition of mTOR. In summary, the present studies highlight miR-100 as a tumor suppressor in chondrosarcoma contributing to anti-chemoresistance. Overexpression of miR-100 might be exploited as a therapeutic strategy along with cisplatin-based combined chemotherapy for the treatment of clinical chondrosarcoma patients.

Metrological determination of a (6 9 17) facet on vicinalSi(5512)using STM

Zhu, Yong-Zhe,Kim, Hidong,Seo, Jae M. American Physical Society 2006 Physical review. B, Condensed matter and materials Vol.73 No.24