RU2390000C1 - Installation for tensile testing plastic materials - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: installation for tensile testing plastic materials has a temperature control container, a specimen loading mechanism with specimen holding elements, a breaking force measurement device and a temperature measurement device. The device also has a load distribution mechanism inside the temperature control container, which is made in form of drums placed between the sample holding elements, where the drums have n turns (where n≥1) of the specimen mainly of plastic threadlike material. The surface of the drum is made from material whose elasticity is equal to or less than that of the material under test.

EFFECT: shorter time for testing threads, increased testing efficiency and increased testing sensitivity when manually loading the threadlike materials, possibility of rapid testing threadlike materials.

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Description

The invention relates to the field of testing equipment intended for tensile testing of plastic materials.

A known installation for testing sheet materials in tension [1], used for testing thin sheet plastic materials (sheet thickness of at least 1 mm), in the clamps of which a sample is fixed with marks applied to it to measure elongation, is held (conditioned) for at least 16 hours at a temperature of 23 ± 2 ° C and a relative humidity of 50 + 5%, and then tear at a speed of 100 to 500 mm / min, while measuring the yield strength and tensile strength using a tensile strength meter.

The disadvantages are the impossibility of testing filamentary samples thinner than 1 mm and the inability to take temperature curves of fluidity and strength of the samples (their cooling is not provided).

Also known installation for testing sheet materials in tension - "Tiratest 2300" [2], which contains a thermostatic tank in the form of a sealed tempering chamber connected to a Dewar vessel with a cooling liquid, such as liquid nitrogen. The sample is placed inside the chamber in an upright position with clamps.

The disadvantages are: fixing the sample in an upright position, causing a large volume and tightness of the chamber, significant consumption of liquid nitrogen, which is most often used as coolant, a long time for one measurement, the high cost of testing thin samples with a sheet thickness of 0.1-0 5 mm.

The closest of the analogues - the prototype is an installation for testing plastic materials in tension, which is designed to test sheet materials [3] or [4] and contains a mechanism for loading the sample with fastening elements of the sample in the form of clamps, a thermostatic container with coolant, a tensile strength meter and a temperature meter, moreover, the thermostatic container is made in the form of a cuvette made of a material with low thermal conductivity and low heat capacity, the clamps of the sample are placed horizontally as the cuvette, and the loading mechanism of the sample is made in the form of a winch, the cable of which is attached to one of the clamps of the sample to ensure its movement relative to the second clamp through the tear force meter, made in the form of a dynamometer with a clamp of breaking forces.

The disadvantages of the prototype is the inability to test samples of plastic filamentary materials, since when using a clamp to secure the sample used in the prototype, the gap occurs close to the clamp, which makes it impossible to measure the moment of the yield point and the tensile strength.

The objective of the invention is to provide an installation for tensile testing of plastic materials from thin 0.1-0.5 mm thick filamentary plastics (fibers) in a wide temperature range during cooling from all sides.

The technical result with the receipt of the specified technical data is achieved by the fact that in the installation for testing tensile materials of plastic materials containing a thermostatic tank, a sample loading mechanism with sample attachment elements, a tensile strength meter and a temperature meter, in contrast to the prototype, a load distribution mechanism is installed a thermostatic container made in the form of drums placed between the fasteners of the sample with n turns wound on them (where n≥1) of the sample, the advantage a plastic filamentary material (fiber), while the surface of the drum is made of a material whose elasticity is not greater than the elasticity of the test material. Using the load balancing mechanism in the form of drums avoids the occurrence of stress concentration at the points of attachment of the test sample, and for preliminary (rough) determination of tensile forces, it is possible to limit winding 1-2 turns. With an increase in the number of turns of fiber winding onto the drums, the transverse and bending forces acting on the fiber and distorting the results of measurements of tensile forces, i.e. the optimal number of turns of winding on the drums 3 or more. The material of the surface of the drum is selected in accordance with the characteristics of the possible test samples. When testing at the time of loading the test sample, it must slide on the surface of the drum so that friction does not affect the reliability of the tests, so the elasticity of the surface of the drum should not be greater than the elasticity of the test material.

The essence of the proposed solution is illustrated in figures 1-3, which show:

figure 1 - view of the installation for testing plastic materials tensile side;

figure 2 - view of the installation for testing plastic materials in tension from above;

figure 3 is a view along section aa.

The claimed installation for testing plastic materials in tension consists of a thermostatic tank in the form of a cuvette 1 filled with coolant, made of a material with low thermal conductivity and low heat capacity, a temperature meter 2 of the coolant. The cuvette 1 is rigidly attached to the base 3 and provided with a cap 4. If an intensively evaporating cooling liquid such as liquid nitrogen is used, a cap may be provided in the cap 4 with risks applied to it to monitor the behavior of the test sample 5 at the moment when the yield strength reaches . In another part of the cover 4, a slot 6 is made for moving an eye 7 attached to the carriage 8, which is mounted to move along the guides 9, for this, hollow cylinders 10 are inserted from the bottom of the carriage, inserted into the guides 9, which are attached to the wall of the cell 1.

To measure the breaking forces of the test sample 5, a spring dynamometer 11 is used, connected by a cable 12 to the loading mechanism of the sample in the form of a winch 13. The dynamometer 11 is equipped with a moving arrow 14 with a breaking force clamp in the form of a slider 15. The dynamometer 11 is hooked to the eye 7. protruding above the cuvette. the carriage 8 has a rigidly installed first eye for securing the sample 16 and a freely rotating first drum 17 for winding the test sample 5. A second eye for securing the sample 18 and the second drum 19 (also freely rotating located around its axis) are located on a stationary carriage 20, which is rigidly attached to the wall of the cell 1. The first eye 16 and the second eye 18 for securing the sample are offset relative to the center of the carriage 8 and the center of the stationary carriage 20, respectively, in order to make the test sample 5 in the studied part was perpendicularly stretched relative to the first drum 17 and the second drum 19. The displacement is determined by the number of turns and the thickness of the test sample 5.

The test is carried out as follows: the test sample 5 of plastic fibers (filaments) with a thickness of 0.1-0.5 mm of arbitrary cross section is wound on the first drum 17 and the second drum 19, forming n turns (where n≥1), and fixed respectively in the first eye 16 and a second eye 18 for securing the sample. The thermostatic tank, made in the form of a cuvette 1, is filled with coolant, the temperature of which is measured by a thermometer 2.

To measure the breaking forces, a spring dynamometer 11 is used, connected by a cable 12 to a winch 13, which is rotationally driven manually or mechanically. To accurately record the force at break of the test sample 5, a slider 15 is used, moved by the arrow 14 of the dynamometer, while the slider 15 does not slide due to its horizontal position and remains in place after breaking the sample 5 and returning the arrow 14 to the zero position. The level of coolant is slightly 5-10 mm higher than the level of arrangement of sample 5. The test sample 5 is held for 2-3 minutes, then they begin to load with a tensile force - rotation of the winch 13; under the influence of the tension of the cable 12 through the dynamometer 11, hooked to the eye 7 on the carriage 8, providing movement of the first eye to secure the test sample 16 and the first drum 17, the force is transmitted to the test sample 5, and it stretches. The arrow 14 of the dynamometer moves, fixing the magnitude of the force when the yield strength and tensile strength are reached and acting on the slider 15, which at the moment of breaking remains at the mark corresponding to the tensile strength of the sample 5, and is recorded visually or using a recording device, while arrow 14 returns to zero.

Using the inventive installation makes it possible to reduce the time of testing the threads by 10-15 times, increase the efficiency of the tests and increase the sensitivity of the tests at the time of manual loading of the filamentary materials, and most importantly the ability to conduct express tests of filamentary materials.

Information sources

1. GOST 11150-84. “Metals. Tensile tests at low temperatures "

2. RU 2089873 C1, G01N 3/08, 10.09 1997.

3. GOST 11262-80. Plastics. Tensile test method.

4. A device for testing the strength. Tiraster 2300. Thuringer Industrialverk, Rauenstein, East Germany, 1989 - prototype.

Claims (1)

Installation for testing plastic materials in tension, containing a thermostatic container, a mechanism for loading a sample with fastening elements of a sample, a tensile strength meter and a temperature meter, characterized in that a load balancing mechanism is inserted in it, placed in a thermostatic tank, made in the form placed between the fastening elements a sample of drums with n turns wound on them (where n≥1) of a sample, mainly plastic filamentary material, while the surface of the drum is made of material whose elasticity is equal to or less than the elasticity of the test material.

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