Abstract:
A test apparatus provides an applied load to a monoball through a trolley which moves along a loading axis. While applying the load to the monoball, the torque meter is in communication with the spherical monoball, and a load cell senses the application of applied force to the monoball. Meanwhile, a rotary actuary imports rotary oscillating motion to the monoball which is sensed by a position sensor and a torque meter. Accordingly, a processor can determine the coefficient of friction in substantially real time along with a cycles per second rate.

Description:
ORIGIN OF THE INVENTION 
   This invention was made by an employee of the United States Government together with government support under contract awarded by the National Aeronautics and Space Administration and may be manufactured and used by or for the Government for governmental purposes without the payment of any royalties thereon or thereof. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to an apparatus for testing single ball bearings lubricants and/or materials in an oscillating rotary motion, and more particularly to such a test apparatus capable of providing environmental conditions including specific temperature, humidity, vacuum, atomic oxygen and other space simulated environmental conditions while monitoring the applied load, resisting torque, angle of rotation and/or coefficient of friction in real time. 
   2. Prior Art 
   A variety of lubricant and material test apparatuses have been produced. Falex Corporation maintains a web presence at www.falex.com and displays a number of test apparatuses they currently market and sell. None of these apparatuses are believed to test the performance of lubricants or materials relating to a single ball bearing subjected to oscillating rotary motion. 
   U.S. Pat. No. 6,324,899 shows a bearing sensor integration for a lubrication analysis system which allows various parameters of lubrication fluid to be sensed while the bearing is in  use. The sensor integration described and shown in the &#39;899 patent does not provide a testing apparatus for testing a monoball and the materials and/or lubricants utilized on a monoball in an oscillating early motion. Additionally, U.S. Pat. No. 6,196,057 shows an integrated multi-element lubrication sensor and lubricant health assessment which includes at least two sensors collecting data relating to a particular parameter of a fluid. This technology shown and described in this apparatus appears to be very similar to that taught in U.S. Pat. No. 6,324,899 also owned by Reliance Electric Technologies, LLC. 
   U.S. Pat. No. 6,009,764 shows a frequency discrimination type torque tester for use in determining bearing quality. This frequency discrimination type torque tester apparently breaks down a torque acting between an outer and an inner racing of a bearing into a spiky change component and an undulated change component. U.S. Pat. No. 6,003,229 shows an apparatus and method of precisely preloading a bearing onto a shaft. Neither of these devices are believed to be used as test apparatus for oscillatory rotary motion of spherical monoballs, lubricants and materials subjected to a measured applied loading and torque. 
   U.S. Pat. No. 5,959,189 shows a test apparatus of lubricating system with performance of rolling bearings. Specifically, the apparatus analyzes performance of a test bearing under different axial loads, rotating speed and lubrication conditions. This apparatus is not configured to evaluate spherical bearings under high loads, only roller type bearings and the condition of the lubricating system. 
   U.S. Pat. No. 5,633,809 shows a multi-function fluid flow monitoring apparatus with a velocity sensor capability. This device is a fluid phase monitoring apparatus which does not test bearings.  
   U.S. Pat. No. 5,275,258 shows an apparatus for detecting bearing-seize conditions in a reciprocating machine. This apparatus evaluates a condition of a liquid lubricant in a journal bearing and does not test solid film lubricants or greases in a slow oscillating motion under high loads. 
   U.S. Pat. No. 5,226,308 shows a system for testing bearings which utilizes a pair of spaced bearings and a bearing holder with an annular collar for holding the bearing to be tested. The bearing holder may be utilized to assist in applying a radial load to the bearing. This test apparatus is utilized with roller bearings under radial loads. It cannot be configured to test spherical bearings in a slow oscillating motion under high loads. 
   While numerous efforts have been made to test lubricants and materials with various bearings, there still exists a need to test a spherical bearing, lubricants and materials subjected to an oscillating rotary motion, particularly when under high load conditions in a controlled environment. 
   SUMMARY OF THE INVENTION 
   A need exists for an improved test apparatus for testing spherical ball bearings, lubricants and/or materials in oscillating rotary motion. 
   Another need exists for an improved oscillating rotary motion test apparatus for testing monoball bearings, lubricants, and/or materials under at least one of predetermined environmental conditions, torque conditions, oscillating rotation up to 280 degrees and/or cyclical rates from up to six cycles per second. 
   Another need exists for an oscillating rotary motion test apparatus capable of providing at least one environmental condition selected from a predetermined temperature, a  predetermined humidity, a vacuum condition, an atomic oxygen concentration, and/or other simulated space environment. 
   Accordingly, a test apparatus applies a load to a monoball through a trolley which preferably configured to move only in the direction of the loading force. While applying a load to the monoball, oscillating rotary motion may be provided by a rotary actuator so that the monoball specimen, lubricant and/or material may be tested and sensed with sensors during testing. A load cell is useful to measure the applied load through the trolley to the specimen. The rotary actuary is equipped with a torque meter to measure resisting torque and a coupling may be utilized to account for misalignment, wear or compression of the monoball test specimen. A position sensor is connected to the shaft to measure angle of rotation of the shaft. 
   Finally, a data acquisition and control system is provided to receive data from the position sensor mounted on the shaft, the torque meter, and a compression load cell configured to measure the load imparted by the trolley on the monoball specimen so that a number of cycles and coefficient of friction may be calculated in real time and stored for post processing. Accordingly, control signals may be sent to the hydraulic cylinder and/or rotary actuator by the system. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The particular features and advantages of the invention as well as other objects will become apparent from the following description taken in connection with the accompanying drawings in which: 
       FIG. 1  is a side view of the test apparatus preferred by the present invention; 
       FIG. 2  is a top view of the test assembly shown in  FIG. 1 ; and  
       FIG. 3  is a schematic drawing of the data acquisition and control system utilized in conjunction with the test apparatus shown in  FIGS. 1 and 2 .  
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Accordingly,  FIGS. 1 and 2  show a test apparatus  10  from a side and top view, respectively. The test apparatus  10  is comprised of a load applicator in the form of a hydraulic cylinder  12  which has an extendable piston  14  which contacts trolley  16 . The hydraulic cylinder  12  of the load applicator is preferably configured to apply a load ranging from about 100 pounds to about 50,000 pounds of force or more. At the upper range of these loadings, the hydraulic cylinder  12  has been found to be a preferable load applicator. Other load applicators may be utilized in other embodiments. 
   The trolley  16  is preferably configured to travel along load axis  18 . In fact, as shown in  FIGS. 1 and 2 , load axis  18  is linear and the trolley  16  is restricted to motion solely to travel along the load axis  18 . Cam rollers  20 , 22 , 24 , 26  connected to trolley  16  are restrained from lateral motion by lateral supports  28 , 20 , 32 , 34 . Accordingly, the trolley  16  is unable to travel in lateral motion by the lateral supports  28 , 30 , 32 , 34 . However, the rollers  20 , 22 , 24 , 26  are moveable longitudinally, i.e., parallel to the load axis  18  so that the trolley  16  is moved toward and away from a specimen  36  with the extension and a withdrawal piston  14 . 
   Once the piston  14  contacts load cell  38  and the contact face  40  contacts the specimen  36  up against receiver face  42 , additional pressure from the hydraulic cylinder  12  applies a load which is measured by load cell  38 . Depending on the amount of load applied, the load cell  38  records different loads applied through the trolley  16  on opposing sides of the contact face  40  and receiver face  42  which contact the specimen  36 . Accordingly, a predetermined load may be applied and maintained by the hydraulic cylinder  12  through the trolley  16  to the faces  40 , 42  of opposing specimen  36 . The contact face  40  and receiver face  42  for mating surfaces which  oppose the specimen  36 . The specimen  36  includes one or more monoball bearings (i.e., a single spherical bearing) and the applied lubricant and/or materials, if any. 
   Angle plate  44  is useful to support the receiver face  42  and provide a stable platform for receiving the force applied through the hydraulic cylinder  12  along the load axis  18 . The angle plate  44  is preferably secured to table top  46  as illustrated in  FIGS. 1 and 2 . Additionally, the lateral supports  28 , 30 , 32 , 34  are also similarly secured to the tabletop  46 . Finally the hydraulic cylinder  12  is also preferably secured to the table top  46 . The trolley  16  is preferably restrained to travel along the load axis  18  but is not restrained to the table top  46 . Additional cam rollers (obscured from view) are located below the trolley to support the weight of the trolley on the tabletop  46 . These rollers which are obscured from view allow the trolley  16  to roll along the load axis while supporting the trolley  16  on the tabletop  46 . 
   The test apparatus  10  is configured of test materials, lubricants and spherical bearings in oscillating rotary motion. In order to impart oscillating rotary motion to the bearing illustrated as specimen  36 , the specimen  36  is connected to shaft  48  such as by being keyed onto the shaft  48  or otherwise connected to the shaft  48 . The shaft  48  may be a Schmidt coupling  50  or be a series of connected shafts to allow for misalignment, wear and/or compression of the test specimen  36 . 
   The Schmidt coupling  50  is also helpful to ensure equal loading on the contact face  40  and receiver face  42  relative to the specimen  36 . Rotary actuator  52  imparts oscillating rotary motion about rotation axis  54  to specimen  36 . It is preferable that the specimen  36  be rotatable through a range of oscillating rotation of up to 280 degrees in the preferred embodiment. Furthermore, the cyclical rate of rotation may vary intermediate anywhere from 0 to 6 cycles per  second, depending upon the test to be run. A torque meter  56  is useful to measure resisting torque of the specimen  36  as it is oscillating under load applied by the hydraulic cylinder  12  through the trolley  16 . Position sensor  58  is useful to sense the angle of rotation of the shaft  48  and thus the angle of rotation of the oscillating specimen  36 . 
   The tabletop  46  is preferably supported by legs  60  so that the test apparatus  10  may be placed in a contained environment  62 . The contained environment allows a predetermined temperature such as a temperature ranging from possible −320 degree Fahrenheit to 1000 degrees Fahrenheit to be applied during the testing conditions. Additionally, another environmental conditions, namely humidity, may be imposed in the environment  62  ranging from 0% to 100% relative. Additionally, the environment  62  may be made to be a vacuum such as a high vacuum or otherwise. The environment  62  may also be made to have a specific atomic oxygen content. Finally, the environment  62  may be made to simulate other space environmental conditions. 
   While  FIGS. 1 and 2  show the mechanical structure of the test apparatus  10 ,  FIG. 3  is useful to understand the data acquisition and control system  64 . Of course, portions of the mechanical system shown in  FIGS. 1 and 2  also comprised portions of the data acquisition control system  64 . After locating the test specimen or specimens  36  on the shaft  48  as shown in Figure, particular lubricants and/or materials such as the material of the bearing or other materials may be applied to the contact face  40 , or receiver face  42 , or to the bearing directly. Accordingly, these lubricants, materials or bearings which form the specimen  36  may be tested by the test apparatus  10 . The heart of the data acquisition and control system  64  is a processor  66  illustrated as an IBM PS2 Model 80. However, many other suitable processors such as a PC Lap Notebook, a desktop computer or even a portable data assistant (PDA) could be utilized. The  processor  66  receives an input from one or more analog to digital (A/D) converters  68  which receives inputs from the compression load cell block  70 , the torque meter block  72  and the position sensor block  74 . The load cell block  70  receives data from the load cell  38  shown in  FIGS. 1 and 2 . The position sensor block  74  receives data from the position sensor  58  and the torque meter block  72  receives data from the torque meter  56  appropriately. The physical connectors from the position sensor  58 , the torque meter  56  and the load cell  38  are not illustrated but are known to those skilled in the art. 
   The data received from the analog digital converter  68  is converted to digital and provided to the processor  66  for processing. The analog to digital converter  68  is preferably a Metrabyte (™) or equivalent fast analog to digital (A/D) input controller card or other appropriate analog to digital controller device. Based upon the data received from the torque meter block  72 , position sensor block  74  and compression load cell block  70 , the processor  66  can calculate the number of cycles and the coefficient of friction substantially in real time. The data may also be stored in the processor  66  for post-processing. In the preferred embodiment, the operator does not need to perform any task once the test apparatus has been started. 
   In order to perform processes, the processor  66  provides command signals preferably to a controller  76  such as a Fluke Helios II, an equivalent micro processor, or other appropriate controller. Of course, the processor  66  and controller  76  may be the same unit in some embodiments. Instructions and/or commands are then provided from the controller  76  to servo controllers  78 , 80  which effectively control the rotary actuator  82  and hydraulic cylinder  84  through servo valves  86  and  88  respectively. Feedback loops  90 , 92  are useful to provide input from the position sensor block  74  back to the servo controller  78  for the rotary actuator  82  and as  well as from the compression load cell  70  to the servo controller  80  for controlling the hydraulic cylinder  84 . Accordingly, the processor  66  and/or controller  76  can provide the necessary commands to specify the loads provided or imposed upon the specimen  36  by the hydraulic cylinder  84  through the load cell  38  as well as the action of the rotary actuator  52  to provide a desired oscillating rotary position as sensed by the position sensor  74  on the specimens  66  so that the applied torque may be measured by the torque meter  72 . 
   The servo controllers  78 , 80  are particularly useful in controlling servo valves of hydraulic systems so that the rotary actuator and hydraulic cylinders  82 , 84  may be hydraulically operated. The hydraulic servo valve  86 , 88  vary the hydraulic pressure and/or flow to the hydraulic cylinder  84  and rotary actuator  82  respectively. Return data may be provided to the processor  66  from the controller  76  depending upon the capabilities of the particular controller  76  selected. If hydraulics are not utilized, the servo controllers  78 , 80  and servo valves  86 , 88  maybe replaced with appropriate devices to control the applied load and position of the specimen  36 . 
   Numerous alternations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to the preferred embodiment of the invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.