RU2488094C1 - Instrument to determine coefficient of static friction force - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: instrument comprises a platform hingedly fixed on a stand, a scale and a traction device. On the platform there is a plate fixed from the investigated material with longitudinal slots of semicircular shape with radius (R), which is larger than the maximum size (r_max) of curvature of the cross section contour of particles of the investigated loose material, but with smaller diameter (2R) of their length (1).

EFFECT: reduced labour intensity of measurements.

3 dwg

Description

The invention relates to measuring devices.

A known device for determining the coefficient of rest friction force, including a platform with an inclined plane articulated on it and a measuring scale (Strelkov L.P. Mechanics. - M .: Nauka, 1975, p. 144).

The proposed device cannot be used to determine the coefficient of rest force of bulk materials, for example, grain, particles of which roll on an inclined plane until the moment of their sliding. The scope of the proposed device is limited to determining the coefficient of rest friction force or uniform motion between flat bodies.

A known device (selected as a prototype) for determining the coefficient of rest friction force, including a platform pivotally mounted on a bed, a measuring scale, a box without a bottom, moved around the platform and filled with viscoplastic material, a traction device (RF Patent No. 2247360, IPC ⁷ G01N 19 / 02, March 31, 2003).

The proposed device does not ensure the efficiency of measurements, since a viscoplastic material requires heating before fixing the particles of the test bulk material in it and subsequent cooling, and for the measurement of the coefficient of rest friction of particles of another bulk material, a laborious operation is required to remove the previous particles from the viscoplastic material.

The purpose of the invention is to reduce the complexity of the measurements.

This goal is achieved by the fact that in the device for determining the coefficient of rest friction force, including a platform pivotally mounted on a bed, a scale and a traction device, according to the invention, a plate of the material to be studied is fixed on the platform with longitudinal semicircular grooves with a radius (R) of large maximum size (r _max ) the curvature of the cross-sectional contour of the particles of bulk material, but with a smaller diameter (2R) of their length (l).

The device is illustrated by drawings, where in Fig.1 shows a General view, in Fig. 2 is a view A in FIG. 1, in FIG. 3 - section BB in figure 1.

The device for determining the coefficient of rest friction force comprises a platform 1 pivotally mounted on a bed 2, a scale 3, a plate 4 with longitudinal grooves 5, in which particles 6 of the test bulk material are placed, a traction device 7.

, по которой рассчитывают коэффициент силы трения покоя по формуле $$f=tg\overline{\alpha }$$

. При повторной серии опытов платформу 1 с закрепленной на ней пластиной 4 опускают вниз с помощью тягового устройства 7, после чего повторяют все операции в указанной последовательности.A device for determining the coefficient of force of rest friction works as follows. In the longitudinal grooves 5 of the plate 4, mounted on a platform 1 previously lowered to the lower position, particles 6 of the test bulk material (for example, grains) are laid. Then, the traction device 7 slowly lifts the platform 1 with the plate 4 fixed on it until the particles 6 begin to slide along the longitudinal grooves 5. In this case, the angles (α) of the particles 6 start to register according to scale 3. According to the recorded values of the angles of the particles begin to slip (α) 6 determine the average value $$\overline{\alpha }$$

according to which the coefficient of rest friction force is calculated by the formula $$f=tg\overline{\alpha }$$

. In a repeated series of experiments, the platform 1 with the plate 4 fixed on it is lowered down with the help of the traction device 7, after which all operations are repeated in the indicated sequence.

The condition r _max <R eliminates the jamming of particles 6 in the longitudinal channels 5. The condition 2R <l eliminates the rolling of particles 6 on the studied surface of the particle 4. The exclusion of time for auxiliary operations in comparison with the prototype (heating and cooling of a visco-plastic material) allows to reduce the complexity of measurements.

Claims (1)

A device for determining the coefficient of rest friction force, including a platform pivotally mounted on a bed, a scale and a traction device, characterized in that a plate of the test material with longitudinal semicircular grooves of radius (R) larger than the maximum size (r _max ) of curvature is fixed to the platform the contour of the cross section of the particles of the investigated bulk material, but with a smaller diameter (2R) of their length (l).

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