Design Of Bearing Test Bed And Study On Characteristics Of Water Lubricated Rubber Bearings

In propeller propulsion system,friction between water lubricated rubber bearing and spindle can cause vibration of the spindle,and even self-excited vibration of the rotating shaft.In order to reduce the vibration and noise from submarine propeller shafting,friction characteristics of water lubricated rubber bearings should be determined firstly.In this paper,a bearing test bed was designed to test friction characteristics of water lubricated rubber bearings at different speeds.Relationship between friction coefficient of water lubricated rubber bearings and bearing specific pressure,movement velocity and whirling vibration load was obtained;Determination of water film stiffness of water lubricated rubber bearings was also done by this test bed.At last,influence of bearing size on friction behaviour of rubber bearings was studied experimentally.In this paper,following work has been done:Chapter 1 introduces background and significance of relevant studies,and international and domestic research status about water lubricated rubber bearings.Chapter 2 introduces design requirements and function principle of the bearing test bed,and then introduces each part of the test bed,such as the servo motor,rotor bearing system and test loading device,the lubricating means and the sensor system.In chapter 3: Bearing stiffness when bearing load varies from no-load to full load and when bearing load changes in the vicinity of the quiescent operating point has been tested by the test bed.Results show that rotational speed has little effect on bearing water film stiffness,water film stiffness is much higher than series stiffness of main shaft and rubber bearing.Chapter 4 introduces relationship between friction coefficient of water lubricated rubber bearings and bearing specific pressure,movement speed and cyclotron vibration load.Without eccentric mass disposed around counterweight-plate,experiments have been designed to test friction coefficient of water lubricated rubber bearings at different stages,spindle speeds,and bearing pressures.Numerical fitting and mathematical modeling of the test data is established.Results show that friction coefficient of water lubricated rubber bearing decreases with increase of spindle speeds while bearing pressure remains constant.Change distribution of copper alloy and plastic counter weights in counterweight-plate,then counterweight-plate would produce centrifugal load on spindle.Experiments have been designed to test friction characteristics of water lubricated rubber bearings under centrifugal loading.Results show that unbalanced load is equivalent to the effect of increasing bearing loads,and the impact is mainly manifested in the middle period,because at low speeds,centrifugal force is too small,while at high speeds,dynamic lubrication is formed,change of friction characteristics of the two cases is not easy.In chapter 5: With the same material and structure,two kinds of concave type bearings with diameter 150 mm and 100 mm are respectively arranged on 150 mm bearing test bed and 100 mm bearing test bed for test,test results show that friction characteristics of small size bearings can not directly replace friction characteristics of large size bearings.However,after friction characteristics of two bearings are modeled and compared,it is found that there is a similarity between friction characteristics of the two bearings.