The RCF 2 Rolling Contact Fatigue Machine is a cut-down version of the TE 92HS Microprocessor Controlled Rotary Tribometer, the key change being the removal of the friction torque measuring arrangement and the clutch assembly used for low speed sliding four ball tests. The RCF 2 machine is used only in the high speed configuration with rolling contact test adapters.
Various well established test adapters are available, including the standard rolling four ball test adapter, typically used for generating surface propagated micro-pitting failures, a cone on angular contact bearing adapter and a thrust ball bearing on disc adapter, which produces rolling with contact spin. All these rely on the high speed test spindle bearings to react the applied axial load. In addition to these, modifications have been made to the spindle and housing to allow back-to-back testing of angular contact bearings. This arrangement results in no axial load on the test spindle, allowing loads up to 40 kN to be applied to the test samples.
The RCF 2 has servo controlled low inertia pneumatic loading with force transducer feedback and vector speed controlled motor speed with encoder feedback. The machine is floor-standing.
Motor and Test Spindle
The test spindle projects downwards and runs in a housing with precision greased for life bearings. The drive motor is connected directly to the drive spindle via a smooth drive belt and pulley. The motor is mounted on a sliding plate with a jacking screw to tension the drive belt. The drive ratio is 6.67:1. This means that for a motor speed of 1,500 rpm the test spindle is rotating at 10,000 rpm. Vector control of the motor with encoder feedback provides a variable speed turn-down ratio of 100:1.
Location for holders for the rotating specimens is provided by a tapered hole in the end of the test spindle and the accurately machined outer diameter and end face of the spindle. The test adapters are mounted directly onto the machine loading beam, which runs on linear bearings.
Thermocouples are located in the adapters to measure the temperature of the test sample (either material or lubricant) and this measurement is used as the feedback for control. The temperature is maintained by software PID controllers.
Rolling contact fatigue tests require the machine to be shut down by detecting the onset of pitting. A piezo-electric sensor is mounted on the machine frame to detect vibration levels. The sensitivity of the detection circuit is adjustable by the operator. A sudden rise in the level of vibration, caused by the pitting damage in the test adapter, will trip the circuit and stop the motor rotating.
Control and Data Acquisition
Control and data acquisition are implemented via host PC running COMPEND 2020 Windows compatible software, in conjunction with a Phoenix Tribology USB micro-controller interface.
Automatic control is implemented via user programmable test sequences. Manual control is implemented using on screen toggles. Data is stored to hard disc in either .csv or .tsv file formats.
RCF 2/10 Standard Load Actuator Assembly
10 kN 1,840 rpm 5 kN 3,000 rpm 3 kN 10,000 rpm
RCF 2/40 High Load Actuator Assembly
RCF 2/1 Rolling Four Ball Adapter
RCF 2/2 Cone on Angular Contact Bearing Adapter
RCF 2/3Thrust Ball Bearing on Disc Adapter
RCF 2/4 Back-to-back Bearing Adapter
RCF 2/5 Roller Thrust Bearing on Disc Adapter
This adapter is essentially similar to RCF 2/3, but uses one half of a standard size 81208 TN roller thrust bearing, loaded against a flat lower disc sample, of chosen material. The standard bearing cage is used to locate the rollers, with the cage centred by a spindle mounted deep groove ball bearing.
RCF 2/LS Lubricant Service Module
A lubricant service module is required for all types of test adapter except the standard rolling four ball adapter. The module has a sump tank with immersion heater, delivery and scavenge pumps and oil to water heat exchanger, for cooling.
Contact Configurations: Rolling Four Ball Adapter Cone on Angular Contact Bearing Adapter (Bearing 7206) Thrust Ball Bearing on Disc Adapter (Bearing 51208) Roller Thrust Bearing on Disc Adapter (Bearing 81208 TN) Back-to-back Bearing Adapter (Bearing 7209 x 2) Rotational Speed: 100 to 10,000 rpm Standard Load Range: 10,000 N Back-to-back Load Range: 40,000 N Spindle Bearing Load: 10,000 N @ 3,000 rpm 4,000 N @ 10,000 rpm Motor: 2.2 kW ac @ 1500 rpm 50% overload available for 30 seconds Heated Block Power: 550 W Temperature Sensor: k-type thermocouple Vibration Sensor: piezo-electric type with adjustable threshold sensitivity and cut-off time Interface: Phoenix Tribology USB micro-controller interface Software: COMPEND 2020 Controlled Parameters Rotational Speed Temperature Load Test Duration Recorded Parameters Rotational Speed Temperatures Number of Revolutions Test Duration Vibration Sensor Output Services Electricity: 220/240 V, single phase, 50/60 Hz, 3 kW Clean, dry air: 4 cfm at 8 bar (120 psi) Installation Floor-standing machine: 900 x 600 x 2000 mm high, 250 kg Bench-mounting cabinet: 530 x 420 x 300 mm high, 20 kg Packing Specifications: 2.2 m3, GW 600 kg, NW 450 kg
hertzian contact pitting rolling bearing materials rolling contact rolling contact fatigue rolling element bearing taper roller bearing
SKF Holland KITECH Korea
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