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%.



 

Same patents:

FIELD: measuring technique.

SUBSTANCE: method comprises determining the force of dynamic braking down of the measuring wheel when its rotation energy is converted into the electric energy as a heat energy at the active load.

EFFECT: enhanced precision.

3 dwg

FIELD: tool-making industry.

SUBSTANCE: device for measuring adhesion qualities of road cover contains supporting frame, imitator of tire with standard protector samples and their tightening weights, triggering mechanism. Supporting frame is made of telescopic sections entering one another with one central and two jointed swiveling side posts with possible fastening in T-like position. Posts contains extendible pins, holding the frame on the surface of road cover during measurements. Tire imitator and a set of flat tightening weights are combined in common body with water reservoir and dispensing mechanism for sprinkling it onto road cover. Spring engine for moving tire imitator is made with possible cocking thereof by manual drive through a reducer, is also equipped with controller of spring pre-tightness and variable-speed gear for movement speed and traction force of moving branch of pulley block. End of chain of moving branch of pulley block is held in variable-speed gear in accordance to required movement speed of tire imitator on road cover, determined by means of stopwatch with automatic enabling/disabling, performed simultaneously with start-stop of rotation of replaceable circular diagram of automatic recorder with dynamometer, built into immobile branch of pulley block and measuring the value of traction force.

EFFECT: possible measurement of forces of sliding friction and friction of rest in longitudinal and transverse directions of motorway road cover in tire contact zone.

2 dwg

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

FIELD: agriculture.

SUBSTANCE: method comprises modeling the process of interaction of water flow with a rough surface by changing the working member of the sloping chute for a precision member with the smooth surface, measuring the height of the water flow in the entrance and exit sections of the chute by means of micrometer with measuring needle, determining the flow rate, and measuring the width of the chute. The smooth member is changed for the working member provided with a rough surface, and the height of the water in the exit section of the chute is measured.

EFFECT: simplified method.

4 dwg

FIELD: engineering of equipment for friction tests.

SUBSTANCE: as sample holder a shaft is used, which is connected by means of connecting rod mechanism to swinging movement drive, made with possible setting of shaft rotation angle and its rotation speed during rotation for given angle. On top of sample a counter-sample is mounted with its own holder. Sample loading unit abuts by rollers on counter-sample holder. Measuring system includes forces indicator, connected to counter-sample holder, sample movement indicator, connected to its holder, indicator of load output, connected to samples loading unit, optical-mechanical indicators, each one of which is made in form of disk with slits pinned onto axis of arrow of appropriate indicator between emitter and photo-detector, and is connected to computer through mouse port.

EFFECT: increased trustworthiness and precision of tribological characteristics of round and spherical bodies during rotation thereof.

6 cl, 3 dwg

FIELD: test equipment.

SUBSTANCE: machine can be used for testing materials and lubricant matters for complicated trajectories relatively movement of interacting friction pairs. Two-coordinate friction machine has base, sample's holder, two-coordinate drive, counter-body's holder, loading mechanism interacting counter-body, two-component force detector connected with counter-body's holder, program control system and friction force main vector instant value automated estimation system. Two-coordinate drive is made in form of two independent movable carriages which move at mutual-perpendicular directions. Holder of flat sample is disposed onto one carriage and counter-body's holder, loading mechanism interacting with holder and two-component force detector connected with holder of counter-body are disposed on the other carriage. Program control system is made in form of control computer connected with independent control modules and with electric engines through matching unit. Electric engines drive two-coordinated drive into motion to provide movement of indicator which interacts with working surface of sample along continuous nonlinear two-dimensional trajectory.

EFFECT: widened functional abilities; improved precision; better truth of result.

4 cl, 1 dwg

FIELD: investigating or analyzing materials by mechanical methods.

SUBSTANCE: device comprises base, holder for specimen mounted on the base, carriage with holder for counter-body, loading unit, meter of friction force, drive for moving one of the holders, guide secured to the carriage perpendicular to the surface of the specimen, rod that can be set in translational motion in the guide, loading unit mounted at one of the ends of the rod, pivot mounted at the other end of the rod, holder made of a rod whose one end is secured to the axle of the pivot and the other end is provided with counter-body, spring, meter of friction force mounted on the carriage oppositely from both sides of the holder of counter-body and parallel to the plane of the specimen at the same distance from the axis of the pivot to the working surface of the specimen. The spring locks the holder of counter-body perpendicular to the working plane of the specimen. The axis of rocking of the pivot is parallel to the surface of the specimen and perpendicular to the direction of movement of the specimen and counter-body.

EFFECT: expanded functional capabilities.

1 cl, 1 dwg

FIELD: measurement technology; test equipment.

SUBSTANCE: method intends for inspection of rolling bearings, plain bearings and bearing units in instrument engineering, mechanical instrument engineering and electric machine engineering. One ring of bearing is loaded with permanent radial force and the other one is brought into oscillatory motion with specified frequency and amplitude by means of electro-mechanical system made of sync electric motor provided with active rotor and with two windings on stator. One winding is connected with dc source and the other one is connected with ac source. Alternative current is measured in second winding. Angular speed of oscillations of rotor is measured additionally and equivalent dissipative factor is calculated as product of constitutive factor of electric motor and relation of average meaning of current value product during period by speed to average square speed within the period.

EFFECT: improved precision of measurement.

1 dwg

FIELD: investigating or analyzing materials.

SUBSTANCE: method comprises measuring parameters of the pavement and calculating the grip coefficient. First, the ordinate of the micro-profile of pavement is measured, and then the dependence y = f(x), which describes the micro-profile in a given section, is determined. The dependence is used for determining the length of the curve of micro-profile, and parameters Ki of the pavement roughness are determined from the formulae proposed.

EFFECT: simplified method and reduced cost of determining.

2 dwg

FIELD: investigating or analyzing materials.

SUBSTANCE: device comprises housing, mechanism for loading, specimen holders that are provided with parallel bearing planes and mounted one opposite to the other. One of the holders cooperates with the loading mechanism. The mandrel provided with the spherical indenter is interposed between the specimen holders. The device has the mechanism for rotation of the indenter around its axis and unit for measuring the applied moment. The mechanism for rotation of the indenter is made of the lever secured to the mandrel, segment secured to the lever, and flexible link that embraces the segment and undergoes the load.

EFFECT: expanded functional capabilities.

1 dwg

FIELD: tribometry.

SUBSTANCE: device has the platform which is provided with an article and set on rollers, drive for reciprocating, unit for loading articles, and pickups for recording forces and displacements .

EFFECT: enhanced accuracy of testing.

1 cl, 3 dwg

FIELD: measuring engineering.

SUBSTANCE: instrument has platform pivotally connected with the base, box without bottom filled with plastic material, tie-rod device, bearing member which can be adjusted in height with spacers and guides mounted on the plate. The layer of material comprises particles. The box is connected with the platform through a damping link provided with arresting carrier.

EFFECT: enhanced accuracy of measurements.

2 dwg

FIELD: plastic metal working.

SUBSTANCE: method comprises calculating the stress-strain condition of the tool and blank with regard for their materials and geometry, plotting a diagram "deformation force - friction coefficient" of the process of plastic deformation, determining experimentally the deformation force, which corresponds to the actual condition of the surfaces of tool, blank, and lubricant, and determining friction coefficient from the diagram.

EFFECT: enhanced accuracy and reduced labor consumption for determining.

3 dwg

FIELD: investigating or analysis of material.

SUBSTANCE: method comprises determining the limit value of the stress by measuring the angle of inclination of the surface which is provided with the initial material. The device comprises changeable coating with projections and locking member made of a frame having thin baffles or thin film made of an adhesive agent.

EFFECT: improved method.

2 cl, 3 dwg

FIELD: investigating or analyzing materials.

SUBSTANCE: device comprises housing, mechanism for loading, specimen holders that are provided with parallel bearing planes and mounted one opposite to the other. One of the holders cooperates with the loading mechanism. The mandrel provided with the spherical indenter is interposed between the specimen holders. The device has the mechanism for rotation of the indenter around its axis and unit for measuring the applied moment. The mechanism for rotation of the indenter is made of the lever secured to the mandrel, segment secured to the lever, and flexible link that embraces the segment and undergoes the load.

EFFECT: expanded functional capabilities.

1 dwg

FIELD: investigating or analyzing materials.

SUBSTANCE: method comprises measuring parameters of the pavement and calculating the grip coefficient. First, the ordinate of the micro-profile of pavement is measured, and then the dependence y = f(x), which describes the micro-profile in a given section, is determined. The dependence is used for determining the length of the curve of micro-profile, and parameters Ki of the pavement roughness are determined from the formulae proposed.

EFFECT: simplified method and reduced cost of determining.

2 dwg

FIELD: measurement technology; test equipment.

SUBSTANCE: method intends for inspection of rolling bearings, plain bearings and bearing units in instrument engineering, mechanical instrument engineering and electric machine engineering. One ring of bearing is loaded with permanent radial force and the other one is brought into oscillatory motion with specified frequency and amplitude by means of electro-mechanical system made of sync electric motor provided with active rotor and with two windings on stator. One winding is connected with dc source and the other one is connected with ac source. Alternative current is measured in second winding. Angular speed of oscillations of rotor is measured additionally and equivalent dissipative factor is calculated as product of constitutive factor of electric motor and relation of average meaning of current value product during period by speed to average square speed within the period.

EFFECT: improved precision of measurement.

1 dwg

FIELD: investigating or analyzing materials by mechanical methods.

SUBSTANCE: device comprises base, holder for specimen mounted on the base, carriage with holder for counter-body, loading unit, meter of friction force, drive for moving one of the holders, guide secured to the carriage perpendicular to the surface of the specimen, rod that can be set in translational motion in the guide, loading unit mounted at one of the ends of the rod, pivot mounted at the other end of the rod, holder made of a rod whose one end is secured to the axle of the pivot and the other end is provided with counter-body, spring, meter of friction force mounted on the carriage oppositely from both sides of the holder of counter-body and parallel to the plane of the specimen at the same distance from the axis of the pivot to the working surface of the specimen. The spring locks the holder of counter-body perpendicular to the working plane of the specimen. The axis of rocking of the pivot is parallel to the surface of the specimen and perpendicular to the direction of movement of the specimen and counter-body.

EFFECT: expanded functional capabilities.

1 cl, 1 dwg

FIELD: test equipment.

SUBSTANCE: machine can be used for testing materials and lubricant matters for complicated trajectories relatively movement of interacting friction pairs. Two-coordinate friction machine has base, sample's holder, two-coordinate drive, counter-body's holder, loading mechanism interacting counter-body, two-component force detector connected with counter-body's holder, program control system and friction force main vector instant value automated estimation system. Two-coordinate drive is made in form of two independent movable carriages which move at mutual-perpendicular directions. Holder of flat sample is disposed onto one carriage and counter-body's holder, loading mechanism interacting with holder and two-component force detector connected with holder of counter-body are disposed on the other carriage. Program control system is made in form of control computer connected with independent control modules and with electric engines through matching unit. Electric engines drive two-coordinated drive into motion to provide movement of indicator which interacts with working surface of sample along continuous nonlinear two-dimensional trajectory.

EFFECT: widened functional abilities; improved precision; better truth of result.

4 cl, 1 dwg

FIELD: engineering of equipment for friction tests.

SUBSTANCE: as sample holder a shaft is used, which is connected by means of connecting rod mechanism to swinging movement drive, made with possible setting of shaft rotation angle and its rotation speed during rotation for given angle. On top of sample a counter-sample is mounted with its own holder. Sample loading unit abuts by rollers on counter-sample holder. Measuring system includes forces indicator, connected to counter-sample holder, sample movement indicator, connected to its holder, indicator of load output, connected to samples loading unit, optical-mechanical indicators, each one of which is made in form of disk with slits pinned onto axis of arrow of appropriate indicator between emitter and photo-detector, and is connected to computer through mouse port.

EFFECT: increased trustworthiness and precision of tribological characteristics of round and spherical bodies during rotation thereof.

6 cl, 3 dwg

Up!