Gdansk University of Technology Faculty of Mechanical Engineering Machine Design and Maintance Department. PG-II 1L Test rig for journal bearings

Transcription

1 Gdansk University of Technology Faculty of Mechanical Engineering Machine Design and Maintance Department PG-II 1L Test rig for journal bearings

2 1. INTRODUCTION The stand PG II-1 L is one of the many test machines which are installed in the research laboratory of the Faculty of Mechanical Engineering, Machine Design and Maintenance Department. It was built in 1970-ies and since then has been modified many times. It is used for different kinds of research both scientific and industrial. 2. DESCRIPTION Test rig PG II 1Ł is used for testing static characteristics of journal sliding bearings. General view of the rig is shown below. The stand is fully computer controlled with internal feedback loop for input parameters adjustment and has a computerised data acquisition (high repeatability of test conditions and immunity to interference). Radial force and rotational speed can be changed according to a pre programmed function. Bearings can be tested both with oil, water or innym lubrication (important for ceramic and composite bearings). The stand is equipped with an accurate friction force sensor. Fig. 1 General view of the test rig PG II 1Ł The stand consists of four main units: housing for tested bearings, driving unit, hydraulic units for generating radial force and lubrication of support bearings, automatic control and data acquisition computer system lubricating unit for tested bearings PG II 1L - test rig for journal bearings 2/6

3 Specifications: Radial load: up to N Tilting torque: 5000 Nm Rotational speed: rpm Journal diameter of tested bearings: mm Separated unit of lubrication of the tested bearing (water, oil etc.) Measured quantities: Friction force Radial force Temperature (of sliding elements, of inlet lubrication) Rotational speed Tilting torque Fig. 2 Schematic view of the test rig PG II 1L. Explanation of elements: 1. Test bearing, 2. shaft, 3. support bearing housing, 4. hydraulic cylinder, 5. hydrostatic support, 6. AC motor, 7. friction force pick up, 8. rotational speed transducer, 9. pressure sensor, 10. temperature sensor, 11. friction force sensor, 12. hydraulic fluid supply, 13. temperature panel, 14. PC computer, 15. transducer, 6. Advantech PCL card PG II 1L - test rig for journal bearings 3/6

4 2.1 Housing The tested bearing is fixed in a rigid housing which is supported in hydrostatic bearings. The design of the housing with hydrostatic bearings and piston is shown below. Z housing X Y hydrostatic bearing hydraulic piston Cylinder Fig. 3 Housing for test bearings Friction torque The principles of operation of measuring friction torque is presented in Fig.4 R Q Radial force P Friction force sensor Fig. 4 Friction torque measurement PG II 1L - test rig for journal bearings 4/6

5 2.1.2 Lubrication of tested bearing Fig.5 Schematic view of lubrication of the tested bearing The tested bearing is lubricated by outer independent lubricating unit. It is possible to lubricate the bearing with water, oil with contaminations or other fluids. Lubrication fluid can be initially warmed (oil tank is equipped with the heating and cooling system). 2.2 Driving unit Rotational speed is controlled by a vector type frequency inverter, which allows to test fully loaded bearings in start-up and stop conditions. The engine is fully computer controlled with internal feedback loop. Rotational speed can be changed according to a pre programmed function and it does not depend on value of friction torque generated in tested bearing. It allows to get the value of nominal torque of the electric engine even at motionless shaft. 2.3 Hydraulic units The aims of the hydraulic units are: to generate radial force applied on tested bearing to lubricate supporting bearings It consists of two independent hydraulic systems. PG II 1L - test rig for journal bearings 5/6

6 Fig. 6. Schematic view of hydraulic units 2.4 Automatic control and data acquisition The stand is fully computer controlled with internal feedback loop for input parameters adjustment and has a computerised data acquisition. Radial force and rotational speed can be changed according to a pre-programmed function. It guarantees the repeatability of the tests. The each and every test parameters (the function of load change and function of rotational speed change) are saved as computer file. A special computer program for automatic control and data acquisition is used. The computer system controls following parameters: radial load and the tilting torque of the tested bearing, rotational speed of journal shaft, limit values of signals (for emergency stop). temperature of lubricating oil PG II 1L - test rig for journal bearings 6/6