Device for Evaluation of the Working Surface Fretting Wear Characteristics

Abstract

A device for evaluating working surface fretting wear characteristics comprises a bottom holder with a sample secured thereto, springs displacing in the X and Y direction, multilayer piezo elements moving in the X, Y, and Z directions, a housing, a top plate/holder, a linear air bearing housing, a spherical upper sample, a linear air bearing shaft, a three-way force sensor, a moving support of the flat air bearing and the flat air bearing housing, a high frequency generator, an amplifier, a controller, an electrical filter, a computer, a force sensor signal amplifier, and a flat air bearing. Instead of springs, it can comprise additional multilayer piezo elements moving in the X and Y directions. The device performs testing surface wear under conditions nearer to actual fretting wear conditions, continuously observing friction pair condition changes during testing and evaluating wear characteristics of the tested material more accurately.

Claims

1. (canceled)

2. The device according to claim 8, wherein four piezoelectric elements work in horizontal X and Y directions in pairs, and one piezoelectric element operates in vertical Z direction.

3. The device according to claim 7, wherein each of said two piezoelectric elements operates in pair with a spring of said two springs in horizontal X and Y directions and one piezoelectric element operates in vertical Z direction.

4. The device according to claim 7, wherein said piezoelectric elements of said piezoelectric drive operating in X, Y, Z directions are multilayer.

5. The device according to claim 7, wherein said the force sensor is acoustic.

6. The device according to claim 1, wherein said controller is made modular and comprises two independently controlled modules, synchronizing work of said piezoelectric elements pairs in X and Y directions.

7. A device for the assessment of working surface fretting wear characteristics, said device comprising an upper plate holder mounted in a housing with an upper sample fixed thereto, a bottom plate holder with a flat bottom sample fixed thereto, a computer controlling a measurement and control unit, a measurement system of said unit comprising a three-way force sensor, and a signal amplifier, which has its output connected to said computer, a control system of said unit comprising a signal amplifier connected to a controller connected with a high frequency signal generator and said computer, said signal amplifier controlling a piezoelectric drive, wherein said upper plate holder is attached to said housing via a linear air bearing, said force sensor is installed between said linear air bearing and said upper plate holder, said bottom plate holder has said piezoelectric drive mounted thereto and operating in horizontal X, Y and vertical Z directions, said piezoelectric drive comprising three piezoelectric elements attached to said bottom plate holder directly and attached to said housing via flat air bearings and two springs which are fixed to said housing directly, and said three-way force sensor of said measuring system is connected to said signal amplifier through a signal filter.

8. A device for the assessment of working surface fretting wear characteristics, said device comprising an upper plate holder, mounted in a housing, with an upper sample fixed thereto, a bottom plate holder with a flat bottom sample fixed thereto, a computer controlling a measurement and control unit, a measurement system of said unit comprising a three-way force sensor, and a signal amplifier, which has its output connected to said computer, a control system of said unit comprising a signal amplifier connected to a controller connected with a high frequency signal generator and said computer, said signal amplifier controlling a piezoelectric drive, wherein said upper plate holder is attached to said housing via a linear air bearing, said force sensor is installed between said linear air bearing and said upper plate holder, said bottom plate holder has said piezoelectric drive mounted thereto and operating in horizontal X, Y and vertical Z directions, said piezoelectric drive comprising five piezoelectric elements attached to said bottom plate holder directly and attached to said housing via flat air bearings, and said three-way force sensor of said measuring system is connected to said signal amplifier through a signal filter.

9. The device according to claim 8, wherein said piezoelectric elements of said piezoelectric drive operating in X, Y, Z directions are multilayer.

10. The device according to claim 7, wherein said force sensor is piezoelectric.

11. The device according to claim 8, wherein said force sensor is acoustic.

12. The device according to claim 8, wherein said force sensor is piezoelectric.

13. The device according to claim 8, wherein said controller is made modular and comprises two independently controlled modules, synchronizing work of the piezoelectric elements in X and Y directions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a schematic diagram of a side view of the device where the bottom holder moving system comprises three piezo elements and two springs.

[0013] FIG. 2 is a schematic diagram of a top view of the device where the bottom holder moving system comprises three piezo elements and two springs.

[0014] FIG. 3 is a schematic diagram of a side view of the device where the bottom holder moving system comprises five piezo elements.

[0015] FIG. 4 is a principle schematic diagram of a top view of the device where the bottom holder moving system comprises five piezo elements.

[0016] FIG. 5 is a schematic representation of possible movement trajectories of a contact point C of the bottom and upper samples (workpieces).

DETAILED DESCRIPTION OF THE EMBODIMENT

[0017] The device comprises a bottom holder 1 with a flat lower sample (workpiece) 2 secured thereto, a spring 3 displacing in the Y-direction, a multilayer piezo element 4 moving in the Y-direction, a housing 5, a multilayer piezo element 6 moving in the X-direction, a multilayer piezo element 7 moving in the Z-direction, a spring 8 displacing in the X-direction, an upper holder 9, a linear air bearing housing 10, a spherical upper sample (workpiece) 11, a linear air bearing shaft 12, a three-way force sensor 13, a moving support of the flat air bearing 14, a flat air bearing housing 15, a high frequency generator 16, an amplifier 17, a modular controller 18, an electric signal filter 19, a computer 20, a force sensor signal amplifier 21, a multilayer piezo element 22 moving in the X-direction (can be used instead of the spring 8), a multilayer piezo element 23 moving in the Y-direction (can be used instead of the spring 3) and a flat air bearings 24.

[0018] The device operates as follows:

[0019] The spherical upper sample (workpiece) 11 is secured to the upper holder 9, and the bottom sample (workpiece) 2 is secured to the bottom holder 1. When the workload F is applied on the upper workpiece 11 via the linear bearing shaft 12, the upper workpiece presses the bottom workpiece 2 immobilized in the bottom holder 1. Therefore, the load is applied on the friction pair. The load can be static or alternate. The desirable movement schemes are programmed using software program, installed in the computer 20. Multilayer piezoelectric elements 4, 6, 7, 22 and 23 are controlled via the modular controller 18 and the amplifier 17. When the modular controller 18, using high frequency generator 16 and the amplifier 17, actuates the multilayer piezo element 4, it deforms through the inverse piezoelectric effect (it consequently lengthens or shortens), thereby causing the bottom holder 1 and simultaneously the workpiece 2 to move in the Y-direction (see FIG. 5, h). The multilayer piezo element 6 is actuated in the same way; it deforms and simultaneously causes the bottom holder 1 and workpiece 2 to move in the X-direction (see FIG. 5, j). The modular controller 18 actuates each multilayer piezoelectric element separately. One end of each of the piezo elements 4 and 6 is fastened to the sides of the bottom holder 1 and their other ends are supported in the housing 5 via the flat air bearing 24. The piezo element 7 is actuated by the same principle as the piezo elements 4 and 6, causing the bottom holder 1 and simultaneously the workpiece 2 therewith to move in the Z-direction (see FIG. 5, 1). When the piezo element 7 is actuated, the alternate load acts on the bottom workpiece 2, causing it to move in the Z-direction, and the load at the other end of the multilayer piezo element 7 acts on the flat air bearing housing 15 via the moving support 14 of the flat air bearing. In order to provide 2D or 3D movement to the bottom holder 1 and also to the bottom workpiece 2 (see FIG. 5 a, b, c, d, e, f, g, k), the multilayer piezo elements 4, 6, 7 are actuated simultaneously. Springs 3, 8 stabilize the holder 1 in the X-Y plane. Mechanical and tribological processes occurring in the friction pair (contact area C of the bottom and the upper workpiece) are reflected in the three-way sensor 13, the signal thereof (acoustic or piezoelectric) demonstrating the change of the condition in the friction pair in the course of testing. The signal from the sensor 13 is transferred to the sensor signal amplifier 21 through the electrical signal filter 19, and further to the computer 20. If the multilayer piezo elements 22, 23 are used instead of the springs 3, 8 (see FIG. 4), the construction of the fretting abrasion mechanism is more rigid in the X-Y plane, therefore it is possible to perform tests under bigger loads F on ef the friction pair and create higher amplitude of movement in X and Y directions.

[0020] Due to the new totality of the structural elements and the fact that the multilayer piezo element moving in the Z-direction provides the bottom workpiece with the chosen load and the movement which is perpendicular to the holder, and, treated by the bottom holder moving system, the contact point C of the samples performs a complicated 2D or 3D movement within the wide range of amplitudes in the X, Y and Z-directions, the described device, unlike the prior art, is capable of performing testing of the surface wear under conditions that are more proximate to the actual fretting wear conditions, and of continuously observing changes of the condition of the friction pair during the course of testing, relying on indications of the acoustic or piezoelectric sensor 13, and of evaluating simultaneously wear characteristics of the tested material more accurately.