NSK Precision Co.

Maebashi-shi, Japan

NSK Precision Co.

Maebashi-shi, Japan

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Ohta H.,Nagaoka University of Technology | Matsuura K.,Nagaoka University of Technology | Kato S.,NSK Precision Co. | Igarashi Y.,NSK Precision Co.
Journal of Tribology | Year: 2010

This paper deals with vibrations and acoustic emissions (AEs) of linear-guideway type recirculating ball bearings with a millimeter-sized artificial defect in the carriage. The vibration and AE of one normal bearing without a defect (Type N), and six defective bearings (Types D1-D6) were measured using a linear velocity of 1 m/s. The defects in the bearings range from 1.87 mm to 6.77 mm in length, 2.45 mm to 3.80 mm in width, and 23.3 μm to 68.0 μm in depth. The experimental results show that the pulse amplitudes of the vibrations and AE (both the peak-to-peak and RMS values) of the defective bearings have a tendency to be greater than those of the normal bearing. Both the measured vibration and AE components over 30 kHz increased in the carriages with defects. To explain these increases in the defective bearings, a collision model with balls and one defect in the carriage is presented. That collision model shows that the increases in both the vibrations and AE of the defective bearings are caused by increases in the defect angle. A reasonable correlation exists between the presented collision model and the measured vibrations or AE of the defective bearings. © 2010 by ASME.


Ohta H.,Nagaoka University of Technology | Hayashi S.,Nagaoka University of Technology | Kato S.,NSK Precision Co. | Igarashi Y.,NSK Precision Co.
American Society of Mechanical Engineers, Tribology Division, TRIB | Year: 2010

In this paper, vibrations and acoustic emissions (AEs) of defective linear-guideway type recirculating ball bearings under grease lubrication were measured. The experimental results show that the vibration and AE amplitudes (the pulse amplitudes, the RMS values) of both the normal and defective bearings have a tendency to be reduced when a grease with higher base oil viscosity is used. Under the same type of grease, the RMS values of the vibrations and AE of the defective bearings increase as the defect angle increases. However, the increases of the RMS values due to increased defect angle are reduced when a grease with higher base oil viscosity is used. Copyright © 2010 by ASME.

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