RU2455631C1 - Device for determining molecular component of coefficient of friction - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: device for determining molecular component of coefficient of friction has a base and a loading mechanism. The device also has, opposite each other with possibility of converging, sample holders with parallel supporting planes, one of which interacts with the loading mechanism, an arbour between the holders, on which a spherical indenter is mounted, a mechanism for turning the indenter about its axis and an apparatus for measuring torque applied to the indenter. The mechanism for turning the indenter is in form of a rigidly mounted arbour, which can turn in a plane perpendicular to the supporting plane of the samples. The device is fitted with a magnetic conductor on which there is an electromagnetic coil which forms, together with the plate, sample holders, samples and spherical indenter, a magnetic loop with an adjusted air gap, and a current source connected by current conductors to the samples. The mechanism for turning the indenter is in form of an arbour, one of the ends of which is connected through a reducer to a motor, and on the other end, in the bearing of an upright post, there is a cam which is in contact with spring-loaded rollers. Samples which are held in the holders through electrical insulation with possibility of movement, are supported by springs resting in stoppers mounted on the plate through electrically insulating spacers. The sample holders have an alternating movement mechanism in form of an electric motor and two gears, one of which is in contact with the lower holder through an insulating spacer. On the stoppers there are mechanisms for lateral feeding of medium in the direction of rotation of the indenter, which affects the coefficient of friction.

EFFECT: high accuracy of measuring the molecular component of coefficient of friction in the presence of external factors such as feeding intermediate medium acting on the coefficient of friction.

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Description

The invention relates to the field of testing equipment, in particular to devices for determining friction coefficients and their components.

A known device for determining the molecular component of the coefficient of friction [1].

For this, the device is equipped with a magnetic circuit with an electromagnetic coil located on it, which together with the sample holders, samples and a spherical indenter forms a common magnetic circuit, and a current source connected by conductive wires to the samples.

The disadvantage of the described device is the inability to take into account the molecular component of the coefficient of friction from the intermediate medium acting on the coefficient of friction, and only when sliding.

The closest technical solution, selected as a prototype, is a device for determining the molecular component of the coefficient of friction [2].

The device contains a base, a loading mechanism, sample holders mounted parallel to each other with parallel supporting planes, one of which interacts with the loading mechanism, a mandrel located between the holders with a spherical indenter fixed in it, equipped with an indenter rotation mechanism around its axis and a device for measuring the torque applied to the indenter, and the indenter rotation mechanism is made in the form of a rigidly fixed mandrel having rotation in a plane perpendicular to the supporting surfaces of the samples, one end of which is connected to the motor through the gearbox, and a cam in contact with the spring-loaded rollers is mounted on its other end, and the sample holders have a mechanism for creating a reverse-rotational movement in the form of an electric motor and two gears, to increase the accuracy of measurement when exposed to an external environment, which is supplied with electric current, magnetic flux, the impact of the pulsating component of the torque at the same time m combined with rolling sliding and spinning. Samples are mounted in holders through electrical insulation.

The disadvantage of the described technical solution adopted for the prototype is the impossibility of determining the molecular component of the coefficient of friction, taking into account the influence of the intermediate medium affecting the coefficient of friction.

The aim of the invention is to improve the accuracy of measuring the molecular component of the coefficient of friction in the presence of external factors, such as the supply of an intermediate medium acting on the coefficient of friction.

Figure 1 shows a schematic diagram of the proposed device; figure 2 is a section along aa in figure 1.

The device contains a lower base 1 with a mechanism for creating a reciprocating movement of the holders 2 and 8 of samples 7 (Fig. 1), which consists of gears 3 and 4 mounted in bearings 5 and driven by an electric motor 6. Between samples 7 with flat and parallel spherical indenter 10 is installed between the surfaces under study, installed in the lower 2 and upper 8 sample holders with the ability to move through the electrical insulation 9. The indenter 10 is rotationally moved in a plane perpendicular to the plane cam 7, a mandrel 11, one end of which is connected through the gearbox 12 to the engine 13. At its other end, mounted in the bearing 14 of the vertical strut 15, there is a cam 16 in contact with the spring-loaded rollers 17. There is a mechanism for loading the specimens 7 with axial force 18 mounted on uprights 19.

Samples 7 are supported by springs abutting against the stops 21 mounted on the plate 22 through electrically insulating gaskets 23 (Fig. 2). To create external influences in the contact zone, the device is equipped with a magnetic circuit 24 with an electromagnetic coil (not shown) located on it, as well as a current source (not shown) connected to the test samples 7 by means of lead wires. In order to create a magnetic flux, mainly passing through the contact zone, the lower holder 2 is isolated from the gear 4 by an insulating gasket 25. The magnetic circuit 24 is in close contact with the lower holder 2 through the magnetic conductor 26, and with the upper 8 through an adjustable air gap Δ, forming a common circuit for the passage of magnetic flux through the samples 7.

The limiters 21 are equipped with mechanisms for supplying the intermediate medium 27 along the rotation of the indenter 10 into the contact zone of the indenter 10 and samples 7. The moment is measured by a measuring device (not shown).

The device operates as follows. Two plane-parallel samples 7 are fixed in holders 2 and 8. A mandrel with an indenter is installed between them. 10. Using the loading mechanism 18, a compressive load N is applied to the samples. The exposure time of the samples under load must be sufficient to complete plastic deformation in the contact zone of the indenter with the samples and correspond to the standard Brinell test. An alternating or constant voltage is applied to the electromagnetic coil of the magnetic circuit 24, thereby creating a magnetic flux. To enhance magnetic flux, samples 7 and indenter 10 are isolated from gear 4 by spacer 25. A current source is turned on (not shown in FIGS. 1 and 2) and current is supplied to samples 7. Thus, external disturbances act in the contact zone of indenter 10 with samples 7 - magnetic flux and electric current.

The electric motor 6 is turned on and through the mechanism, which consists of gears 3 and 4 installed in the bearings 5, the reciprocating movement of the holders 2 and 8 of the samples 7 is created. In this case, the friction pattern of the rotation of the samples 7 relative to the indenter 10 is realized.

The indenter 10 is applied with a torque M _cr necessary for its rotation in a plane perpendicular to the support planes of the holders, i.e. in the plane compressing the load samples N, realizing a rolling friction scheme with sliding of the samples 7 at the indenter 10. The torque is created by the engine 13 and transmitted through the gearbox 12 along the mandrel 11. At the other end of the mandrel 11 there is a cam 16, which under the action of the spring-loaded rollers 17 ( shown one) creates a pulsating component of the moment on the mandrel. Since the samples 7 are spring-loaded by the springs 20, they, moving in a plane perpendicular to the compressive load N, implement a rolling friction scheme with the sliding of the samples 7 on the indenter 10 during compression and tension of the corresponding springs 20, if there is a pulsating moment component in the contact zone.

By changing the magnitude of the torque of the engine 13, it is possible to realize a different amount of slippage in the contact zone of the samples 7 and the indenter 10. To change the magnetic flux between the samples 7 and the indenter 10, the air gap in the magnetic circuit Δ is regulated. Measure the moment M with a special device (not shown).

From the measured values of the moment M and load N determine the molecular component of the coefficient of friction.

During the operation of the friction unit using the supply mechanisms of the intermediate medium 27 along the rotation of the indenter 10, an intermediate medium, for example, oil, rainwater, water suspension, sand, etc., is fed into the contact zone of the indenter 10 and samples 7.

Thus, in the described device, the accuracy of measuring the molecular component of the friction coefficient is increased in the presence of an external factor, such as an intermediate medium, for example, oil, rainwater, water suspension, sand, etc.

Information sources

1. RF patent No. 2279664, M. K. G01N 19/02, publ. 07/10/06, bull. No. 19.

2. RF patent No. 2315283, M. K. G01N 19/02, publ. 01/20/2008, bull. No. 2.

Claims (1)

A device for determining the molecular component of the coefficient of friction, containing a base, a loading mechanism, sample holders mounted against each other with parallel support planes, one of which interacts with the loading mechanism, a mandrel located between the holders with a spherical indenter fixed in it, indenter rotation mechanism around its axis and a device for measuring the torque applied to the indenter, and the indenter rotation mechanism is made in the idea of a rigidly fixed mandrel that can be rotated in a plane perpendicular to the supporting surfaces of the samples, the device is equipped with a magnetic circuit with an electromagnetic coil located on it, which forms, together with the plate, sample holders, samples and a spherical indenter, a magnetic circuit with an adjustable air gap and a source current connected by conductive wires to the samples, the indenter turning mechanism in the form of a mandrel, one of the ends of which is connected to the motor through a gearbox lem, and on its other end, mounted in the bearing of the upright, there is a cam in contact with the spring-loaded rollers, samples installed in the holders through electrically insulated with the ability to move, supported by springs abutting against the stops installed on the plate through insulating gaskets, and sample holders have a mechanism of reciprocating movement in the form of an electric motor and two gears, one of which is in contact with the lower holder through an insulating gasket, characterized the fact that the limiters are equipped with mechanisms for supplying a third-party medium along the rotation of the indenter, which affects the coefficient of friction.

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