SK412017A3 - Rotary microtribometer for evaluation of tribological properties of surfaces and coatings of construction materials - Google Patents

Abstract

The three-point frictional contact element rotary micrometer with flexible head and thrust head for the evaluation of the tribological properties of surfaces and coatings of construction materials as a test facility allows microscopic and submicroscopic examination of friction and wear processes. The design consists of a flexible rotating head (1) consisting of three concentric circular rings. The outer ring (5) forms the frame and the central ring (6) and the inner ring (7) are rotatable relative to the X and Y axes. The axes of the joints (8) of one ring are perpendicular to the axis of the joints of the second ring. A sample (3) of the material to be tested is attached to the inner ring (7). The frame as an outer ring (5) is rotatable about the Z-axis and its rotational movement is performed by the drive unit (4). The contact pressure is provided by the pressure head (2), which forms the second member of the tribological pair and allows to place either three balls or three pins to form a three-point contact. An array of upper weights (12) and lower weights (13) of varying masses in conjunction with Earth's gravity provides the required normal force value Fn in the three-point contact of the friction bodies (11). The sample (3) of the material under test is subjected to forces, namely the vertical normal force Fy from the set of upper weights (12) and the lower weights (13) and the horizontal frictional force Ff, which is generated by the rotational movement in contact between the friction bodies (11) and sample (3) from the test material. The rotary movement of the pressure head (2) is captured by a force-sensitive force transducer (20) having one end tangled in the retainer clips (21) and the other free end of the blade engaging the notches in the upper weight system (12) and bottom weights (13) . The three-point contact solution and the flexibly attached sample (3) of the material to be tested make it possible to achieve a continuous and continuous supply of energy to the point of contact throughout the test.

Description

The invention relates to the design of a laboratory test apparatus, a rotating meter with a flexible head and a pressure head with a three-point arrangement of friction contact members as an apparatus for assessing the tribological properties of surfaces and coatings of samples of structural materials. The invention generally belongs to the field of mechanical engineering.

BACKGROUND OF THE INVENTION

Methods for investigating the tribological process are known in the art, and devices for carrying out them are also known. The real tribological system is investigated on a tribological model which shows, from a tribological point of view, a similarity to the real or ideal friction node that allows for a mutual description. The tribological process is characterized by the material interactions of the friction bodies, the intermediates and the environment, which take place in space and time. It is always about creating a sliding pair - a tribological node in the environment (atmosphere, water, dust, etc.), with the possibility to model the processes of friction and wear, and simultaneously to measure and record parameters of these processes.

A number of different configurations of laboratory experimental test facilities are currently used in the research of friction and wear processes, which are categorized according to the prevailing wear anism mechanism, the nature of the energy impulses, the type of friction and the nature of the contact surfaces. The difference in the design of the test equipment is mainly due to: the geometric shape of the friction node elements

- triboelements, the nature of the tangential contact of the surfaces in the actual mode of operation of the samples under examination, the nature of the load, the type and manner of inference of the relative movement of the tribological pair (samples from the material under investigation and the acting body). Some manufacturers of tribological laboratory test equipment also take into account the energy aspect in the allocation. Depending on the method of supplying energy to the point of contact, the devices divide into: continuous energy devices, minimized energy devices, and cyclic energy devices. The category of devices with continuous energy supply includes testing devices that can be characterized as thermal self-regulating with continuous energy pulses.

The most widespread devices have a simple design and work on the principle of pin - on -

- disc) or ball - on - disc. Devices of this type have only two degrees of freedom (other degrees of freedom are blocked), namely the sliding movement of the pin (balls) in the Z direction and the rotation of the disc around the Z axis. The drive unit rotates a constant sliding speed in one direction a pair around the Z axis (disk). The point of contact is stationary with respect to one of the samples. Their principal advantage is that the instruments can operate in modes with a large load range and speeds and with a wide range of monitored parameters. This type of equipment is used primarily in basic studies of material wear, namely metals, plastics, composite materials, alloys, ceramic materials, coatings and coatings, in non-lubricated and solid-lubricated conditions. In this test method, contact occurs between the ball and the ball respectively. pin and disc. A pin or ball (the ball does not roll, is firmly attached to the contact friction member), slides along a circular path on the disc. The movement is relative, one of the members of the tribological node performing a rotational movement about the Z axis passing through the center of the disk, the disk or the pivot can rotate. Movement is provided by the drive unit eg. electric motor via appropriate mechanical gears. The disadvantages of these solutions are the high demands placed on the preparation of the surface of the friction surfaces of the friction elements, namely the geometric accuracy of the shape of the flatness of the contact surface of the disc surface, respectively. the pin and the front surface throw of the disc surface. Another disadvantage of such a solution is the fact that at low loads e.g. in micro-metric friction tests, the slip may occur at the point of contact during the test, thereby interrupting the continuous and continuous supply of energy to the point of contact. Since the contact plane of the disc cannot be ideally planar, even though it has slight recesses and ridges, there may be dynamic effects in contact with the movement of the ball over the uneven surface of the disc, and thus an uneven contact force. The pressing force is then not constant, which in some cases may affect the results of the experiments. Since the work (heat) generated in the contact is the product of the frictional force and the relative speed, the frictional force is the product of the contact (normal) force and the friction factor (coefficient) in contact, the applied energy is a function of the contact force and circumferential speed.

These shortcomings evoked the design of a different solution system with a flexible disk mounting head.

As a result of this effort, the construction of a test apparatus, a rotary microtnometer for evaluating tribocorrosive properties of surfaces and coatings of construction materials in the present invention is described.

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SUMMARY OF THE INVENTION

These requirements are fulfilled by a test device such as a rotary meter for evaluating the biological properties of the surfaces and coatings of the construction materials of the present invention. Its essence is the optimal spatial arrangement of suitably designed mechanical and electrical elements that create a controlled and measurable tribological node with two members of the tribological pair.

The first member of the tribological pair in disk function is a rotating flexible head with a precisely defined rotational movement on which a sample of the test material is mounted. The rotary motion of the head is generated from the electric motor through the respective mechanical gears with the possibility of speed control. The essence of the design lies in the fact that the flexible head is composed of three concentric ring rings. The outer ring forms a frame and is rotatable about a vertical Z-axis and its rotational movement is discharged from the drive unit. The two inner rings are connected to each other by means of two joints and the central ring is connected to the outer frame respectively. outer ring also using two joints. The joint axes of one ring are perpendicular to the joint axes of the other ring, and the joints are located in the X and Z axes directions. The bearings are housed in the body of the second ring and allow partial pivotal movement over the pins of the second ring. A sample is attached to the inner ring. The result of such a configuration is that the inner rings that are partially rotatable about each other about the X and Y axes and always allow / secure the position of the sample so that the plane of the sample surface coincides with the plane defined by the three touches of the press head.

The second member of the tribological pair is a pressure head with a three-point arrangement of friction contact members - friction bodies (pins or balls). The pressure head is designed to accommodate the friction bodies, either three balls or three pins, so as to establish a three-point contact with the first member of the tribological pair (disc - sample). The bodies are arranged on a pitch circle rotated by 120 °. The radius of the circle is the radius of rotation of the friction bodies. The design of the press head allows it to move in the Z-axis direction and at the same time to rotate (not rotate) about the Z-axis. The rotation of the press head is generated by frictional forces generated in the contacts. The adjustment of the appropriate normal (load) force Fn in contact is performed in conjunction with the gravity of the press head and the controlled relief of the head by means of mechanical adjustment by the cable, spring and pulley system. The load measurement (unloading) is determined by a load cell which consists of two flexible foils, the value of the normal force Fn being determined by measuring the linear deformation of the upper foil. The interaction between the friction members located on the pressing head and the rotating sample mounted on the flexible head is the formation of friction, namely the friction force Ft. The frictional force Ft creates a friction moment M h (Mt = Ft.R) at the contact point, where R is the radius. The intermediate friction moment Mt is absorbed by a strain gauge force sensor, which is in the form of a foil and which deforms linearly due to the applied force. Because of the dynamic contact, the design of the rotary tribometer should have sufficient mechanical stiffness to prevent undesirable vibrations, which may affect the accuracy and stability of the friction process as well as the measurement of the friction force Ft and the like. The solution with three-point contact and flexibly mounted rotating sample allows to achieve uniform contact force, normal force Fn even at not ideal sample flatness and continuous power supply to the point of contact throughout the test. The flexible head solution ensures a uniform distribution of the vertical normal force Fn over each of the three contacts.

The advantages of the design of a laboratory test apparatus, a rotary head caliper with a flexible head and a thrust head with a three-point configuration of friction contact members as an apparatus for assessing the surface properties and coatings of the construction material samples according to the invention are apparent from its external effects. The effects are that the inner rings of the rotary flexible head with a precisely defined rotational movement, which are partially rotatable about each other about the X and Y axes, always allow / secure the position of the specimen so that the plane of the specimen surface coincides with the plane defined by three touches. The pressure head with a three-point arrangement of the friction contact members (pins or balls) with a flexibly attached sample allows to eliminate the geometric unevenness of the specimen surface, thus achieving a constant contact pressure and a continuous supply of energy to the point of contact throughout the test. It also enables microscopic and submicroscopic examination of friction and wear processes.

BRIEF DESCRIPTION OF THE DRAWINGS

A laboratory test apparatus, rotary meter with a flexible head and a pressure head with a three-point arrangement of friction contact members, as an instrument for assessing the biological properties of surfaces and coatings of samples of structural materials constructed according to the invention will be further explained in the drawings. In FIG. 1 is a schematic representation of the pm-on-disc method and the pb-based method. ball-on-disc with continuous power supply at the point of contact.

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In FIG. 2 shows a schematic diagram of a technical solution of a rotating flexible head of a test apparatus. In FIG. 3 shows a rotating flexible head model of the tester. In FIG. 4 shows a model of the press head of the device with a three-touch friction pad arrangement. In FIG. 5 is a cross-sectional view of components of the apparatus in a rotary flexible head, sample, and press head configuration.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that particular embodiments of the invention are presented by way of illustration and not as limitations of technical solutions. Those skilled in the art will find or be able to ascertain using no more than routine experimentation many equivalents to specific embodiments of the invention. Such equivalents will also fall within the scope of the claims.

It is not possible for the person skilled in the art to optimally design the structure, so these features have not been solved in detail.

The requirements listed in the previous chapters are provided by a rotating microtribometer to assess the tribological properties of surfaces and coatings of structural materials, i. j. a test device according to the invention. In terms of construction, the movable part and the static part of the device shown in FIG. 2 to 4. FIG. 5 is their complex arrangement. The movable part of the device is a system with a rotating flexible head 1, whose rotational movement is generated from the electric motor as the driving unit 4 through the respective mechanical gears up to the sample 3 of the test material. The static portion is a set of elements including a pressure head 2, a ball-shaped friction body 11 and also other related non-moving elements. FIG. 2, 3 and 5, it is evident that the rotating flexible head 1 consists of three rings, the outer ring 5 forming a frame and the central ring 6 and the inner ring 7 rotatable relative to each other about the X and Y axes. test material. Frame, t. j. the outer ring 5 is rotatable about the Z-axis and its rotary movement is provided from the drive unit 4 through the respective mechanical gears and connecting flange 15. The central ring 6 and the inner ring 7 are connected to each other by two hinges 8 and the central ring 6 is connected to the outer ring 5, also by means of two joints 8. The axes of the joints 8 are perpendicular to each other and the joints 8 are located in the X and Y axes. The joint 8 consists of a precision bearing 9, a pin 10, and a spacer ring h6. secures by matrix ľ7. One joint of the joints 8 is as follows. The two pins 10 of the hinges 8 are fixed at one end in the central ring 6 and the other ends of the pins 10 are rotatably mounted in the precision bearings 9 of the outer ring 5, thereby fixing the position of the pin 10 firmly. the inner ring 7 and the second ends of the pins 10 are rotatably mounted in the precision bearings 9 of the central ring 6, thereby firmly fixing the position of the pin 10. The outer ring 5 has two technological recesses over the two pins 10 of the hinges 8 connecting the inner ring 7 and the central ring 6. The hinge arrangement allows a partial rotational movement of the central ring 6 about the X-axis and the inner ring 7 about the Y-axis, thereby providing a flexible adjustment of the position of the clamped sample 3 of the test material at the bottom of the inner ring 7.

FIG. 4 shows the structure of the press head 2, which comprises three ball-shaped friction bodies 11 which are glued at the end of the pins 14. The other end of the pin 14 is inserted into the holes in the body of the press head 2, the axial position of the pins 14 being secured by a pair of screws (not shown). By means of a pair of ball bearings 19, a sleeve 18 is rotatably mounted on the shank of the press head 2, which allows both rotational and sliding movement of the press head 2 (only turning because rotation prevents the torque measurement system generated by frictional forces). The system of upper weights 12 and lower weights 13 of different mass, in cooperation with the earth gravity, provides the required value of normal force Fn in the three-point contact of friction bodies 11. Forces 3 of the tested material are subjected to forces (normal) force Fn from the system and the lower weights 13 and the horizontal frictional force Ft which is generated by the rotational movement in contact between the friction bodies 11 and the sample 3 of the test material. The rotational movement of the press head 2 is captured by a foil-shaped force sensor 20 having one end fixed (tethered) in the clips on a separate holder 21 and the other free end of the foil fit into the notches in the upper and lower weights 12. the forces Fn, the frictional force Ft and the frictional moment M are shown in FIG. First

Industrial usability

Rotary microtabineter for evaluation of tribological properties of coatings and coatings of construction materials according to the invention is used in research of surfaces of construction materials, coatings under friction conditions in passive environment (atmosphere, water, dust, etc.), with the possibility to model friction and wear processes also at extremely low loads, measure and record the parameters of these processes.

Claims (6)

Rotary microtribometer for assessing the biological properties of surfaces and coatings of structural materials with two members of a tribological pair, characterized in that it consists of a rotating flexible head (1) with a precisely defined rotational movement which constitutes the first member of the tribological pair on which it is mounted a sample (3) of the test material; the rotary flexible head (1) consists of an outer ring (5) which forms a frame and has a central ring (6) rotatable about the X axis and has an inner ring (7) rotatable about the Y axis; a sample (3) of test material is mounted on the inner ring (7); the outer ring (5) is pivotable about the Z axis and is connected to the drive unit (4) via a connecting flange (15); the central ring (6) and the inner ring (7) being connected to each other by two hinges (8), the central ring (6) being connected to the outer ring (5) equally by two hinges (8); the joint axes (8) are perpendicular to each other and the joints (8) are located in the X and Y axes directions; the joint (8) consists of a precision bearing (9) and a pin (10); and further comprising a pressing head (2) which forms a second member of the tribological pair on which three ball-shaped friction bodies (11) are attached in the pin (14); in this case, the foil-shaped force sensor (20) is mounted on a separate bracket (21) and fits with its free ends into the notches in the upper weights (12) and / or in the lower weights (13) which are mounted on the press head (2). A rotary microtribometer for evaluating the structural properties of surfaces and coatings of structural materials according to claim 1, characterized in that the two pins (10) of the hinges (8) are firmly fixed in one end in the central ring (6) and the other ends of the pins. (10) are rotatably mounted in bearings (9) of the outer ring (5). A rotary microtiter for evaluating the structural properties of surfaces and coatings of structural materials according to claim 1, characterized in that the two pins (10) of the hinges (8) are firmly attached with one end in the inner ring (7) and the other ends of the pins (10). are rotatably mounted in bearings (9) of the central ring (6). Rotary microscope for evaluating the biological properties of surfaces and coatings of structural materials according to claims 1 to 3, characterized in that the outer ring (5) has two technological recesses compared to the two pins (10) of the joints (8) connecting the inner a ring (7) and a central ring (6). ... A rotary microscope for evaluating the biological properties of surfaces and coatings of construction materials according to claims 1 to 4, characterized in that the three friction bodies (11) are ball-shaped. A rotary microtimeter for assessing the biological properties of surfaces and coatings of structural materials according to claims 1 to 4, characterized in that the three friction bodies (11) are pin-shaped.