CN211717954U

CN211717954U - Automatic centering device for material tensile test

Info

Publication number: CN211717954U
Application number: CN201921942828.3U
Authority: CN
Inventors: 刘津强; 赵万忠; 王春燕; 黄云丰; 张自宇; 刘畅; 汪桉旭
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2019-11-12
Filing date: 2019-11-12
Publication date: 2020-10-20
Anticipated expiration: 2029-11-12

Abstract

The utility model discloses an automatic centering device for material tensile test, which consists of a clamping section and a functional section; the clamping section is used for clamping a clamp of the tensile testing machine, and a concave space is arranged in the cuboid main body of the functional section and used for assembling with a test piece. The axis of the concave space is coincident with the longitudinal axis of the cuboid, and the diameter of the upper bottom surface circle of the concave space is larger than that of the lower bottom surface circle. The tensile force is transmitted to the test piece through the two curved surfaces of the concave space, so that the resultant force of the force applied to the test piece in the transverse section of the test piece is zero, the centering property in the transverse section of the test piece is achieved, and the accuracy of the tensile test result is improved.

Description

Automatic centering device for material tensile test

Technical Field

The utility model belongs to the technical field of material tensile test apparatus, concretely relates to material tensile test automatic centering device.

Background

In the field of materials, researchers widely adopt a material tensile test to obtain mechanical parameters such as tensile strength and yield strength of the material. Wherein, the alignment of the clamp of the tensile testing machine directly influences the accuracy of the test result. Therefore, it is necessary to take measures so that the tensile force direction is along the axial direction of the test piece during the material stretching process.

In general, during the design process of the tensile testing machine, the design side takes the centering of the clamp into consideration. However, due to long-term use and aging of the equipment, the centering precision is reduced, and the accuracy of the tensile test result is seriously influenced. In the existing centering scheme, a centering platform installed at the bottom of a clamp of a testing machine is adopted in the Chinese patent application No. CN201410603803.6, and the centering platform is not suitable for the testing machine of which the bottom of the clamp cannot be assembled and disassembled to adjust the platform. A device with a centering function is designed in Chinese patent application No. CN201810783164.4, but the device can only realize centering in one direction and has certain limitation. Based on this, the utility model provides a material tensile test automatic centering device can realize the centering of two vertical direction in the test piece transverse cutting, then in tensile test, the direction of the tensile force that the test piece received is along its axis direction.

Disclosure of Invention

The utility model aims at the not enough of above-mentioned prior art, the utility model aims to provide a material tensile test automatic centering device to solve current tensile test machine and use the back for a long time, equipment is ageing, and the centering precision descends, influences the problem of tensile test result accuracy.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

the utility model discloses a material tensile test automatic centering device, it comprises centre gripping section and functional section, the two integrated into one piece.

Further, the device is of a left-right symmetrical structure.

Further, the clamping section is a symmetrical trapezoid body connected with a cuboid, and the clamping section and the symmetrical trapezoid body are integrally formed.

Further, the length of the cuboid in the clamping section is 40mm, the width is 30mm, the thickness is 14mm, the length of the lower bottom of the trapezoid cross section of the symmetrical trapezoid body is 50mm, the length of the upper bottom is 40mm, the height is 15mm, and the thickness of the symmetrical trapezoid body is 14 mm.

Further, the main body of the functional section is in the shape of a cuboid.

Further, the length of the cuboid in the functional section is 50mm, the height of the cuboid is 40mm, and the thickness of the cuboid is 14 mm; a concave space is arranged in the cuboid, the left wall surface and the right wall surface in the concave space are two curved surfaces, and the axis of the concave space is superposed with the longitudinal axis of the cuboid; the diameter of the upper bottom surface circle of the concave space is 30mm, the diameter of the lower bottom surface circle is 20mm, and the height of the concave space is 20 mm.

The utility model has the advantages that:

the utility model discloses a centering device structural design is reasonable, uses easy operation, can realize the centering nature in the better test piece transverse cut for the test piece tensile force has avoided the influence of the centering nature of clamp to the test result along test piece axis direction all the time. The utility model discloses a researcher who needs to carry out material tensile test provides a fine centering scheme.

Drawings

Fig. 1 is a perspective view of the automatic centering device of the present invention.

Fig. 2 is a front view of the automatic centering device of the present invention.

Fig. 3 is a top view of the automatic centering device of the present invention.

Fig. 4 is a mechanical analysis diagram of the present invention.

Figure 5 the utility model discloses the test piece structure chart.

Detailed Description

In order to facilitate understanding of those skilled in the art, the present invention will be further described with reference to the following examples and drawings, which are not intended to limit the present invention.

Referring to fig. 1-3, the automatic centering device of the present invention is divided into a clamping section 1 and a functional section 2, which are integrally formed;

the clamping section is a flat entity, so that the clamping of the tensile testing machine clamp is facilitated. The clamping section 1 is a cuboid connected with a symmetrical trapezoid body, and the two are integrally formed; the length of the cuboid is 40mm, the width is 30mm, and the thickness is 14mm, the length of the lower bottom of the section trapezoid of the symmetrical trapezoid body is 50mm, the length of the upper bottom is 40mm, the height is 15mm, and the thickness of the symmetrical trapezoid body is 14 mm; the bottom surface of the clamping section is a face 11.

The main body of the functional section 2 is in the shape of a cuboid, the length of the cuboid is 50mm, the height of the cuboid is 40mm, the thickness of the cuboid is 14mm, the upper bottom surface of the cuboid is a surface 21, and the surface 21 is connected with the surface 11 of the clamping section; a concave space is arranged in the cuboid, and the left wall surface and the right wall surface in the concave space are two curved surfaces, namely a surface 23 and a surface 24; the axis of the concave space is superposed with the longitudinal axis of the cuboid; the diameter of the upper bottom surface circle of the concave space is 30mm, the diameter of the lower bottom surface circle is 20mm, the height of the concave space is 20mm, and the upper bottom surface of the concave space is the middle surface 22 in the figure 1; the

faces

23, 24 are symmetrical to the central axis.

The clamping section is clamped by a clamp, and the functional section is assembled with the test piece. The shapes of the two ends of the test piece are concave-convex complementary with the shape of the functional section (namely, concave space), and the two ends of the test piece are also provided with two curved surfaces, namely a curved surface 32 and a curved surface 33; the curved surfaces 32 and 33 are identical to the

curved surfaces

23 and 24 of the functional segments having the concave shapes. The interlude of test piece is the cuboid, connects through the long changeover portion of 30mm between the curved surface 32 at cuboid and test piece both ends, the curved surface 33. After the functional section and the test piece are assembled, the two pairs of curved surfaces of the functional section and the test piece are attached to each other.

When carrying out tensile test, tensile testing machine passes through anchor clamps and applies the tensile force for the utility model provides a centering device, centering device pass through curved surface 23, curved surface 24 and transmit the power for the testpieces, the power perpendicular to curved surface 32, the curved surface 33 that the testpieces received. Fig. 5 is a structure diagram of the test piece of the present invention, in which a surface 32 is engaged with the surface 23 in fig. 1, and a surface 33 is engaged with the surface 24 in fig. 1. Since the side surfaces of the concave space are symmetrical relative to the axis center, the curved surface 32 and the curved surface 33 of the end part of the test piece are also symmetrical relative to the axis center, the shape of any longitudinal section of the end part of the test piece is a trapezoid, and the stress schematic diagram is shown in fig. 4.

The pressure at each point on the curved surface is σ, and the direction is perpendicular to the curved surface, then the force can be decomposed as:

σ_x＝σsinα,σ_y＝σcosα

σ'_x＝σ'sinα,σ'_y＝σ'cosα

because σ is σ', σ_x＝σ'_x. Since the curved surface 32 and the curved surface 33 are symmetrical with respect to the center of the axis, the component forces of the pressure on the transverse section of the test piece can all cancel each other, and the resultant force direction of the test piece is along the axial direction. When the clamp alignment of the tensile testing machine has a problem, namely the central connecting line of the upper clamp and the lower clamp is not coincident with the axis of the test piece, the analysis shows that the resultant force direction of the test piece is still along the axis direction, so that no shearing force exists in the stretching process, and the misalignment of the clamp is corrected.

The utility model discloses the concrete application way is many, and the above-mentioned only is the preferred embodiment of the utility model, should point out, to ordinary skilled person in this technical field, under the prerequisite that does not deviate from the utility model discloses the principle, can also make a plurality of improvements, and these improvements also should be regarded as the utility model discloses a protection scope.

Claims

1. An automatic centering device for a material tensile test is characterized by comprising a clamping section and a functional section which are integrally formed; the clamping section is a cuboid connected with a symmetrical trapezoid body, and the clamping section and the symmetrical trapezoid body are integrally formed; the main body of the functional section is in a cuboid shape.

2. The material tensile test automatic centering device of claim 1, wherein the device is a left-right symmetrical structure.

3. The material tensile test automatic centering device of claim 1, wherein the length of the cuboid in the clamping section is 40mm, the width is 30mm, and the thickness is 14mm, the length of the lower bottom of the cross-section trapezoid of the symmetrical trapezoid body is 50mm, the length of the upper bottom is 40mm, the height is 15mm, and the thickness of the symmetrical trapezoid body is 14 mm.

4. The material tensile test automatic centering device of claim 3, wherein the cuboid in the functional section has a length of 50mm, a height of 40mm and a thickness of 14 mm; a concave space is arranged in the cuboid, the left wall surface and the right wall surface in the concave space are two curved surfaces, and the axis of the concave space is superposed with the longitudinal axis of the cuboid; the diameter of the upper bottom surface circle of the concave space is 30mm, the diameter of the lower bottom surface circle is 20mm, and the height of the concave space is 20 mm.