Testing apparatus for compression and tension samples

Abstract

This utility model relates to mechanical engineering and can be used for testing dissimilar metal pairs under compression and tension, studying friction and contact phenomena, and assessing hardness. The technical result of implementing the claimed utility model is the expansion of the loading device's functionality by automating the loading process with complete electrical and thermal insulation of the working elements.The apparatus for testing samples for compression and tension contains a housing rigidly connected to a thrust crossbar, coupled by means of hinges with four actuators through their rods, connected by hinges of the lower support with a fastening plate, which through a mica electrothermal insulating gasket by means of bolts with ceramic bushings is connected to the upper part of the clamp with a punch rigidly installed in it, coaxially coupled with a matrix rigidly installed in the lower part of the clamp, wherein the actuators are electrically connected to a control unit with the possibility of axial and angular movement of their rods according to specified parameters.

Description

[0001] The utility model relates to the field of mechanical engineering and can be used to conduct compression and tension tests on dissimilar pairs of metals, study frictional and contact phenomena, and assess hardness.

[0002] A loading device is known (patent No. 2700351 IPC G01M13 / 02, published on September 16, 2019). This device comprises a drive, a housing with a cover made with a hollow shaft, a gear reducer installed in the cover, a small gear of which is mounted on the drive shaft, and a large gear on the hollow shaft of the cover, a screw gear installed in the hollow shaft of the cover, a wave reducer, the rigid wheel of which is fastened to the housing, and a flexible wheel is with the screw of the screw gear, and a deformation wave generator connected to the large gear of the gear reducer, wherein the nut of the screw gear in the form of a quill is connected to the cover by means of a keyway, and the flange of the screw is mounted between the housing and the second cover with the possibility of rotation. The screw of the screw transmission is made hollow, connected by an internal thread to a rod installed in it with the possibility of axial movement and provided with a groove with a key placed in it, fixed in the second cover of the housing.

[0003] The disadvantages of the above loading device are the large number of threaded and splined connections, which leads to a decrease in rigidity and accuracy, high cost and increased requirements for the accuracy of manufacturing structural units.

[0004] A known installation for testing samples under compression for long-term and short-term loads (patent No. 127921, IPC G01N 3 / 00 (2006.01), published 10.05.2013), containing upper and lower crossbars fixed on rods, as well as an intermediate crossbar with a support ball installed between them, having the ability to move, nuts located on the rods, a loading system including a source of medium pressure, a piston for loading samples located in a cylindrical cavity of the lower crossbar, a sealed chamber installed under the piston and communicated with the pressure source, a limiting ring for the piston fixed on the lower crossbar, additionally provided with thrust bearings located on the rods between the upper crossbar and the nuts, and the sealed chamber is made in the form of a metal bellows.

[0005] The disadvantages of the analogue are the need to use a compressor to create a compressive force, manual clamping of samples, and relatively low structural rigidity.

[0006] The main task that the claimed utility model is aimed at solving is the creation of an electrically and thermally insulated loading device with the ability to flexibly adjust the force parameter and the angle of force application.

[0007] The technical result of implementing the claimed utility model is the expansion of the functional capabilities of the loading device by ensuring the automation of the loading process with complete electrical and temperature insulation of the working parts.

[0008] The stated problem is solved, and the technical result is achieved by an installation for testing samples for compression and tension, containing a housing rigidly connected to a thrust crosshead, coupled by means of hinges with four actuators through their rods, connected by hinges of the lower support with a fastening plate, which, through a mica electrical heat-insulating gasket, is connected by means of bolts with ceramic bushings to the upper part of the clamp with a punch rigidly installed in it, coaxially mated with a matrix rigidly installed in the lower part of the clamp, wherein the actuators are electrically connected to a control unit with the possibility of axial and angular movement of their rods according to specified parameters.

[0009] The technical result is achieved through the implementation of four actuators, whose duty cycle is monitored in real time by a control unit. Electrical and thermal insulation is achieved by installing a mica gasket and ceramic bushings between the upper part of the clamp and the loading elements.

[0010] The essence of the utility model is explained by a basic diagram, where Fig. 1 shows an installation for testing samples for compression and tension; Fig. 2 is a basic diagram of creating a load at an angle; Fig. 3 is an operating algorithm of the control unit.

[0011] The apparatus for testing specimens for compression and tension comprises four actuators 1, the upper support of which is in the form of hinges 2, fixed in a thrust crossbar 3, rigidly connected to the body 4. The rods 5 of the actuators are connected by hinges of the lower support 6 with a fastening plate 7. The upper part of the clamp 8 with the installed first specimen, which is a punch 9 in the form of a single-sided rod with a spherical end, is rigidly connected to the fastening plate 7 through a mica electrical and thermal insulation gasket 10 by bolts with ceramic bushings 11 without the possibility of axial movement. The matrix 12, made in the form of a solid cylinder and representing the second test specimen, is located coaxially with the punch 9 and is fixed in the lower part of the clamp 8 without the possibility of axial movement. The control unit 13 is connected by an electrical circuit with the actuators 1 connected in parallel.

[0012] When compressive or tensile force needs to be applied at an angle, for example, when studying the frictional properties of samples, the device is started in the "Load at Angle" mode and the desired angle is then entered. The device allows the load application angle α to be varied within a range of ±30° relative to the normal with a positioning error of ±30°. The load application angle can be adjusted through precise control of the actuators 1 and their hinged connection to the mounting plate 7. At the device's zero point, i.e., with the mounting plate 7 in a horizontal position and the extensions of the piston rods 5 equal, the control unit 13 assigns a value of 0° in its own angular coordinate system, in which clockwise rotation produces positive angle values, and counterclockwise rotation produces negative ones.When the operator enters the desired load application angle, the control unit rotates the mounting plate by extending the corresponding actuator rod (right for positive angles, left for negative angles) by a distance equal to the leg of the corresponding right triangle, the hypotenuse of which is equal to the center-to-center distance of the actuator lower support hinges, and the acute angle opposite the aforementioned leg is equal to the specified angle. The control unit calculates using a sine function.

[0013] Control unit 13 is a programmable logic controller (PLC) with a pre-loaded operating program that allows minimizing operator interaction with the plant control process (Fig. 3).

[0014] The setup is turned on by the operator pressing the START button. The required force for the experiment is set on the built-in display. If necessary, the load application angle α can be selected within a range of ±30° relative to the axis. After receiving the load and force application angle data, the control unit checks the position of the rod using a limit switch and, if any misalignment occurs, triggers a return to the zero point command.

[0015] The control unit dynamically checks the actual force on the piston rod against the value specified via feedback channels. Upon receiving a signal indicating the end of the experiment, the obtained data on the actual load is output to a third-party computer.

[0016] The control unit structure provides automatic protection of electrical circuit elements from short circuits (SC) and an operator-controlled emergency shutdown button.

[0017] The proposed installation operates as follows: when the required compressive (uncompressive) force is specified in the control unit 13, the supply current is supplied to the actuators 1, in the housings of which DC electric drives are located, coupled with worm gearboxes, as a result of which pushing forces are generated, moving the rods 5 along their own axes. The rods 5 move the fastening plate 7 along the axis until the punch 9, rigidly fixed in the upper part of the clamp 8, contacts the die 12, rigidly fixed in the lower part of the clamp 8. At the moment of contact between the punch 9 and the die 12, reactive forces appear and, consequently, the load of the actuator drives 1 increases, which is recorded by the control unit 13. To overcome the resistance forces and create a compressive (uncompressive) force, the control unit 13 increases the supply currents of the actuators, which leads to an increase in the pushing forces F on the rods 5.The thrust crosshead 3, installed in the housing 4, absorbs reactive forces and prevents axial displacement of the actuators 1. The mica gasket 10 and ceramic bushings 11 provide complete electrical and thermal insulation of the working elements from the clamp 8 with the punch 9, enabling heating (including by electrical contact) of samples for studying contact (adhesion, diffusion) processes.

[0018] Thus, the proposed technical solution expands the functionality of the loading device by providing automation of the loading process with complete electrical and thermal insulation of the working parts.

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