Method for determining friction coefficient

FIELD: agricultural mechanical engineering, research of friction coefficients of materials.

SUBSTANCE: researched material is positioned on surface made in form of cylinder, rotation frequency of which is determined from formula where n - cylinder rotation frequency, s-1; g - free fall acceleration, m/s2; r - internal radius of cylinder, meters. Researched material is positioned on internal surface of cylinder, while friction coefficient is determined from formula where α - angle of tow of researched material by cylinder, grad.

EFFECT: possible determining of friction coefficient of both solid and free-flowing materials without their advance fastening in special sample.

1 dwg

 

The invention relates to the field of agricultural engineering, namely to research methods of coefficients of friction materials.

There is a method of determining the coefficient of friction, based on the placement of the studied material on an inclined plane. The angle of inclination of the plane to the horizon increases until, until you start moving the investigated material. This is the desired angle and the friction angle, respectively, the tangent of this angle is equal to the coefficient of friction /1/.

The disadvantage of this method is that so impossible to conduct a study of the coefficient of friction of granular materials without the prior locking them in a special pattern.

The closest technical solution of the present invention is a method of determining the coefficient of friction, including the friction of the studied material on the rotating surface, made in the form of a flat disk, under the action of centrifugal force and the friction force is the deviation of the sample, which is then recorded on the chart. Finally the coefficient of friction is found by comparison of the obtained table and calibration schedule /2/.

The disadvantage of this method is the inability to conduct a study of the coefficient of friction of granular materials without the prior locking them in specially enom sample.

The present invention is the determination of the coefficient of friction of solid and granular materials without the prior locking them in a special pattern.

This object is achieved in that the surface on which is placed the material made in the form of a cylinder, the speed of which is determined by the formula

where n is the rotational speed of the cylinder, with-1;

g - free fall acceleration, m/s2;

r is the inner radius of the cylinder, m,

moreover, the studied material is placed on the inner surface of the cylinder, while the coefficient of friction is determined by the formula

where α - angle zataskivanija investigated material cylinder, grad.

The drawing shows the setup diagram for determining the coefficient of friction.

The device includes a cylinder 1 mounted on the shaft, the bearings and the drive mechanism 2. Inside the cylinder is analyzed material 3. The device includes a graduated angular scale 4 located in the lower part of the unit, and the index angle 5. The installation consists of a set of cylinders 1, made of different materials.

The device operates as follows.

The cylinder 1, due to the drive mechanism 2, performs rotational motion is at a constant rate n, certain of the expression

where g is the acceleration of gravity, m/s2; r is the internal radius of the cylinder, m If the speed is greater, it is possible seizure of material due to centrifugal force and its involvement in a circular motion together with the cylinder /3/. Reducing the speed will adversely affect the accuracy of the research. Due to the friction force of the investigated material 3 will zataskivatj the inner surface of the cylinder 1 at a certain angle α relative to the lower point of the inner surface of the cylinder 1. This angle is determined using the angular scale 4 and moved manually pointer angle 5. The coefficient of friction is determined by the formula

/3/.

Literature

1. Klenin N Agriculture and melioration machines. / Nighlty., Vascon. - M.: Kolos, 1994, p.18-21.

2. Salikov M.V. Agricultural machinery. Part II. / MVision. - M.: Kolos, 1968, p.6-8.

3. The engineering. The encyclopedia. Ed. Tip: Frolov (pre), etc. M.: engineering. Agricultural machinery and equipment. T IV - 16 / Ifacename, Geparinov, Nan and others; Ed. by Ipersonalize. 1998. - Pp.272.

The method for determining the coefficient of friction, including the friction of the studied material on the rotating surface, characterized in, Thu the surface, hosting study material, made in the form of a cylinder, the speed of which is determined by the formula

where n is the rotational speed of the cylinder, with-1;

g - free fall acceleration, m/s2;

r is the inner radius of the cylinder, m,

moreover, the studied material is placed on the inner surface of the cylinder, while the coefficient of friction is determined by the formula

where α - angle zataskivanija investigated material cylinder, grad.



 

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