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Cui H.-Z.,Shandong University of Science and Technology | Li Y.-F.,Shandong University of Science and Technology | Sun J.-Q.,Shandong University of Science and Technology | Li B.-M.,Shandong Best Precision Co Ltd | And 2 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2013

Induction quenching for GCr15 steel ball screw with magnetic flux leakage controlling by coating magnetizer was investigated. Microstructure, hardness, depth and wear resistance of surface induction-hardened layer were analyzed, respectively. The results indicate that the quenched layer microstructure consists of martensite and retained austenite. By coating magnetizer, the density of magnetic lines on the surface of ball screw and the temperature of induction heating are increased. And also the depth of hardening layer is increased and the gradient of hardness curve is decreased. Therefore, the wear resistance of the samples with magnetizer is improved significantly, and is increased by 2.5 to 4 times comparing with that of the unquenched sample. Abrasive wear and stripping layer wear are the main wear mechanisms for the induction-hardened sample. The abrasive debrises are thick and with rough fracture surface for the samples by conventional induction quenching, however, by coating magnetizer, the abrasive debrises of the samples are thin and with smooth fracture surface, which indicates good abrasive resistance.


Wang W.,Shandong University of Science and Technology | Cui H.-Z.,Shandong University of Science and Technology | Wang Z.-N.,Shandong University of Science and Technology | Sun J.-Q.,Shandong University of Science and Technology | Li B.-M.,Shandong Best Precision Co Ltd
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2015

The surface of 50CrMo4 (German) steel ball screw was induction quenched, and then tempered at low temperature. The phase constitution, microstructure, microhardness, residual austenite content in quenched layer of the steel were analyzed. Moreover, the wear characteristics of quenched layer under dry friction condition and different loads were investigated. Results reveal that the microhardness of the quenched layer increases from 250 HV to 700 HV and the microstructure is mainly composed of fine tempered martensite. The fracture morphology from the surface to matrix is intergranular fracture, dimple and transgranular fracture, and dimple fracture respectively. Furthermore, the friction coefficient decreases with increasing friction load. At the low load the grooves are observed in the wear surface and the wear mechanism is abrasive wear. With the increasing of friction load some pits begin to appear on the wear surface, and the number of it is increasing. However, at the high load, deep grooves and large flakes are observed, the wear mechanism is the mixture of serious abrasion and delamination. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.


Jiang H.-K.,Shandong Jianzhu University | Song X.-C.,Shandong Jianzhu University | Li B.-M.,Shandong Best Precision Co. | Tang W.-C.,Shandong Jianzhu University | And 2 more authors.
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2012

The contact-impacts between balls and a ball-returner in running process causes noise of a ball screw mechanism, and it leads to decrease in the service life of the ball screw mechanism. In order to solve this problem, the contact-impact dynamic model between ball and a returner was proposed, and a new evaluation index for recirculation fluency of ball-chain in a ball returner was introduced. Based on the analysis, a new double-arc passage profile of ball was presented, and the optimal geometric parameters were obtained based on genetic algorithm. The results proved that the optimal solution can not only decrease the contact-impact force between balls and a returner but also make the recirculation of ball-chain smoother. The double-arc passage profile of a ball returner and the optimal method could be applied to design of other types of ball returner.


Wang Q.,Shandong University | Tian J.,Shandong University | Ding X.,Shandong University | Li B.,Shandong Best Precision Company Ltd | And 2 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2013

The over distortion of 45 steel mainshaft quenched as well as quenched and tempered was analyzed through microstructure and hardness test. It is found that the microstructure is uneven with ferrite network due to the non-uniform cooling in different positions of the mainshaft during heat treatment process. Accordingly, the countermeasures such as eliminating ferrite network by normalizing and adopting subcritical hardening were proposed.


Gai Y.H.,Shandong University | Yan Y.,Shandong University | Li C.N.,Shandong University | Li B.M.,Shandong Best Precision Co. | And 2 more authors.
Applied Mechanics and Materials | Year: 2014

Failure analysis on the GCr15 bearing steel and the 20CrMo carburized steel nuts was performed after two sets of fatigue tests of GD8020×1100 ball screw pair. By means of scanning electron microscopy observation, energy dispersive analysis and microhardness testing, it is found that there is an obvious indentation, slight pitting and microcracks on the raceway of the GCr15 bearing steel nut and shows the characteristics of contact fatigue failure. The nonuniformity of microstructure and the lower carbon and chromium content in the indentation, leading to local lower hardness, account for the nut failure. While the raceway of the 20CrMo carburized steel nut is more rough with scratches caused by the damaged steel balls so as to show the characteristics of wear failure. Therefore there are different failure ways for the different nuts made by different steels and heat treatments under the same fatigue testing condition. © (2014) Trans Tech Publications, Switzerland.


Wang Q.,Shandong University | Li M.,Shandong University | Ding X.,Shandong University | Li B.,Shandong Best Precision Company Ltd | Dong Q.,Shandong Best Precision Company Ltd
Advanced Materials Research | Year: 2013

This paper dealt with the fracture failure of a GCr15 steel ball screw nut. Through testing and analysis of hardness, microstructure, scanning electron microscopy and energy dispersive spectrum meter, it was found that there are local carbide network, few oversized carbide particles and metallic inclusions. The analysis showed that carbide network was failed to be eliminated through spheroidizing annealing treatment, while the presence of non-uniform carbide particles and metallic inclusions easily induced the crack and consequently led to the fracture of the nut. © (2013) Trans Tech Publications, Switzerland.


Ding X.,Shandong University | Yan Y.,Shandong University | Wang Q.,Shandong University | Li B.,Shandong Best Precision Co. | Li M.,Shandong University
Advanced Materials Research | Year: 2013

The band microstructure has an adverse effect on the comprehensive mechanics performance of Cr-Mo steel used for ball screw. This paper dealt with the different annealing processes combined with the forming mechanism of the banded structure. It shows that the annealing with long time can basically eliminate the band microstructure. © (2013) Trans Tech Publications, Switzerland.


Ding X.,Shandong University | Wang Q.,Shandong University | Li B.,Shandong Best Precision Co. | Dong Q.,Shandong Best Precision Co. | And 2 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2012

There is local difficult processing in 45 steel parts after normalizing or quenching and tempering treatment, and it was tested and analyzed by hardness, chemical composition, microstructure, scanning electron microscopy and electronic spectroscopy etc. The results show that the microstructure of the 45 steel bars is uneven, and there is ferrite network, banded segregation, local troostite and some metallic or non-metallic inclusion. The original tissue defects can be improved by recrystallization annealing to meet the machining performance requirements of 45 steel parts.


Yang J.,Huazhong University of Science and Technology | Wei Z.,Huazhong University of Science and Technology | Zhu J.,Shandong BEST Precision Co. | Du W.,Shandong BEST Precision Co.
Huazhong Keji Daxue Xuebao (Ziran Kexue Ban)/Journal of Huazhong University of Science and Technology (Natural Science Edition) | Year: 2011

According to the Hertz theory of elastic contact, taking the roller as the object, the three types of the deformations were analyzed and calculated theoretically, including roller screw and the point contact between the thread groove of the Hertz deformation; roller screw and nut in contact with axial deformation; screw and nut, respectively, with the roller contacts deformation when thread. A mathematical model and analysis of the load distribution law and axial static rigidity for the planetary roller screw were put forwarded and programmed by the Matlab software, and the rigidity curve of the planetary roller screw was obtained. Compared with the test data, the accuracy of the calculation method and results were verified.


Yan Y.,Shandong University | Li C.N.,Shandong University | Gai Y.H.,Shandong University | Li B.M.,Shandong University | And 2 more authors.
Applied Mechanics and Materials | Year: 2014

By means of chemical composition testing, scanning electron microscopy observation, metallographic observation and hardness gradient detection etc, analysis of the typical failure samples from a well-known brand GD8020×1100 ball screw unit in the fatigue test was carried on. Results show that there is no obvious surface wear of the ball screw, showing the normal contact fatigue failure. But severe surface wear happens on the raceway of nut A with obvious flaking and many local cracks; which is the main reason leading to the failure of ball screw unit. So effective measures to avoid earlier failure of the ball screw unit can be put forward by controlling the steel quality strictly and improving the hardness and depth of the hardened layer on the raceway of nut A. © (2014) Trans Tech Publications, Switzerland.

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