Toshio Teshima

Rolling Friction Lubricated with Solid Lubricants

Recently, the high temperature lubrication of rolling bearings using powder solid lubricants have been investigated, and we have studied and reported it. For the purpose of obtaining the fundamental data about the high temperature lubrication of rolling bearings lubricated with solid lubricants, rolling friction is measured using a simple rolling friction apparatus in which two balls are rolled between the two flat surfaces under load. The experimental results obtained are as follows : Taking the rolling resistance F, load on ball W, diameter of ball D, Brinell hardness number of flat surface PH, F is proportional to W1.5, D-1.7 and PH-2.0 respectively. There exist the most suitable quantities of lubricants, and the rolling resistance increases rapidly when the quantities of lubricants exceed the most suitable quantities. Allowable load capacity of contact point between ball and flat surface is increased owing to the lubrication with solid lubricant. We are able to comfirm the lubrication performances of solid lubricants by means of microscopic observation of grooved track.

On the Graphite-Air Mist Lubrication of the Ball Bearing at High Temperature

The need is becoming more and more urgent for bearings operating at very high temperatures. But present-day liquid lubricants are temperature-limited owing to their characteristics, but graphite is chemically more stable and capable of being used as a lubricant. So in pursuit of information concerning the performances of the angular contact type ball bearing operating in an electric furnace under the graphite-air mist lubrication at high temperature, the frictional moment and temperature of bearing have been measured. The conclusion reached on the experimental results is as follows. The bearing can be run at surrounding temperatures up to 800°C without appreciable damage. The smaller the particles of graphite, the less frictional moments are obtained, but at very high temperatures the grading and consumption of graphite have little influence on the frictional moment. Small change in frictional moment occurs in accordance with variation of surrounding temperature. The moisture content of graphite has little influence on the frictional moment. The cooling effect of air is somewhat remarkable.

Crush-Dressing of Grinding Wheel

In this paper the life of crushing roll, the wear of formed grinding wheel and the accuracy of the ground workpiece in the practice of crush-dressed form-grinding are investigated. The experimental results are as follows : -(1) The smaller the grain and the lower the peripheral speed of wheel and in-feed speed of crushing roll, shorter the life of crushing roll. But at higher speeds both peripheral and in-feed, the grinding wheel becomes apt to be cracked.(2) The wear of crush-dressed wheel in the grinding practice is not so much. However, the loading of wheel seems to occur owing to the increased length of contact arc in the contour-grinding.(3) The dimensional accuracy of ground workpiece may be kept in more or less 10.

The Oil Bath Lubrication of Ball and Roller Bearings at High Speed

In pursuit of information concerning the performances of the high speed rolling bearings operating under oil bath 1ubrication and light load, measurements of bearing temperature rise and friction coefficient have been made using radial ball and roller bearings of 40mm bore with pressed cages. As the lubricant, spindle oil or turbine oil is applied and the level of oil bath is always kept in somewhat lower than the centre of rolling element which is placed at the lowest position in the bearing. The experimental results of bearings, operated at a rotating speed up to 24, 000 rpm for the ball bearing and 16, 000 rpm for the roller bearing, indicate that the bearing temperature rise and friction coefficient increase proportionally to the rotating speed of bearing. From the fact that bearings had been operated securely under such high speed, it may be convinced that, under light load, the oil bath lubrication can be applied for a speed far higher than the speed which is adopted customarily under the limitation of dn-value of 250, 000. Furthermore, at such a high speed, the friction coefficients of bearings under oil bath lubrication take the values nearly twice as the values lubricated with minimum oil, and such differences depend on the hydrodynamic friction losses owing to churning oil.