# Method of determining friction coefficient

FIELD: test engineering.

SUBSTANCE: method comprises moving the specimen over the horizontal surface to be tested by means of a weight suspended on thread that passes over the block, determining time that is required for the specimen to cover 1-m distance, and determining the friction coefficient form the formula presented.

EFFECT: enhanced precision.

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 by measuring direct dynamometrical friction of the sample on the sample surface and dividing it by the normal pressure of roaming sample /1/.

The disadvantage of this method is the low accuracy.

The closest solution to the proposed method of determining the coefficient of friction is a method consisting in the movement of the sample under investigation horizontal surface by means of cargo, suspended by a thread and thrown through the block, the coefficient of friction is defined as the ratio moves the sample strength to normal pressure, and the weight of cargo should be selected such that the sample is moved evenly /2/.

The disadvantage of this method is low accuracy and complexity.

The present invention is the determination of the friction coefficient with greater accuracy and less time.

This object is achieved by moving the sample under investigation horizontal surface by means of cargo, suspended by a thread and thrown through the block, is fixed at the same time move the sample on the meter section, and the greater the friction is determined by the formula

where M is the mass of the cargo, kg;

m is the mass of sample, kg;

S - the path traversed by the sample, m S=1 m);

t - time move the sample in the path S, s;

g - free fall acceleration, m/s2,

the weight of the cargo M greater than the mass of the sample m 10-20%.

The drawing shows a diagram of the device for implementing the method of determining the coefficient of friction.

The investigational device includes a horizontal surface 1 with on her sample 2. Sample 2 is connected to the load 3 thread 4, which is thrown through the block 5. The structure of the device is also included elektroskandia 6, which through electrical wiring associated with the switching sensor 7 and the sensor off 8 installed respectively at the beginning and at the end of the metre plot's horizontal surface 1. In addition, before switching sensor 7 elektroskandia 6 has a clamp 9 sample 2, and the sensor off 8 elektroskandia 6 and before the block 5 is the stop 10.

Proposed method is as follows.

Initially, the sample 2 is installed on the investigated horizontal surface 1 in the latch 9. Then the latch 9 is released, and the sample 2 slides on the analyzed horizontal surface 1 under the force of gravity acting on the load 3. The weight of the load 3 more sample mass 2 by 10-20%, which is about especial steady movement of the sample 2 on the analyzed horizontal surface 1. Moving the sample 2 consistently acts on the sensor on 7 elektroskandia 6 and the sensor off 8 elektroskandia 6 installed to simplify further calculations on a one-meter distance from each other. However elektroskandia 6 starts and then turns off, fixing the time of moving the sample under meter station S. after Passing the sensor off 8 elektroskandia 6, sample 2 stops at stop 10. The coefficient of friction is determined from the expression

where M is the mass of the cargo, kg;

m is the mass of sample, kg;

S - the path traversed by the sample, m S=1 m);

t - time move the sample in the path S, s;

g - free fall acceleration, m/s2.

Literature used

1. Salikov M.V. Agricultural machinery. P.II. / MVision. - M.: Kolos, 1968, p.7.

2. Salikov M.V. Agricultural machinery. P.II. / MVision. - M.: Kolos, 1968, p.7 - prototype.

The method for determining the coefficient of friction, which consists in moving the sample under investigation horizontal surfaces with load, suspended by a thread and thrown through the block, wherein the fixed time of moving the sample on the meter section, and the coefficient of friction is determined by the formula

where M is the mass of the cargo, kg;

m is the mass of sample, kg;

S - the path traversed by the sample, m S=1 m);

t - time move the sample in the path S, s;

g - free fall acceleration, m/s2,

the weight of the cargo M greater than the mass of the sample m 10-20%.

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