Sample preparation device and sample preparation method for shear force test

Abstract

The invention relates to a sample preparation device and a sample preparation method for shear force test, the sample preparation device comprises a first cover plate, a second cover plate, a sample preparation device and a sample preparation method, the first cover plate is provided with a first groove; a second groove is formed in the second cover plate, and the depth of the second groove is larger than that of the first groove; during sample preparation, the second cover plate and the first cover plate are mutually covered, the surface where the first groove is located is opposite to the surface where the second groove is located, the first groove and the second groove are mutually staggered, and part of the first groove and part of the second groove are overlapped in the thickness direction to form a communication part. The first groove and the second groove are communicated with each other through a communication part; and the size of the communication part is consistent with that of a standard required shearing area. The method disclosed by the invention is easier to operate and simple in steps, the sample preparation time can be saved, the sample preparation efficiency can be greatly improved, and the test sample required by the shear force test can be prepared without an extruder, so that the material cost, the starting cost and the labor cost are saved.

Description

Technical Field

[0001] The invention relates to the technical field of cable shear force testing, in particular to a sample preparation device and a sample preparation method for shear force testing. Background Art

[0002] At present, with the continuous expansion and upgrading of infrastructure construction such as energy and transportation, the market prospects of smooth aluminum sheathed high-voltage power cables are very broad. The basic structure of smooth aluminum sheathed high-voltage power cables is as follows: Figure 1 As shown, from the inside out, it includes a water-blocking conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, a wrapping, a smooth aluminum sheath, a hot melt adhesive, a HDPE sheath, and a graphite layer. As a result, the demand for smooth aluminum has also increased accordingly. In various tests of smooth aluminum cables, the shear force between the non-metallic outer sheath layer and the aluminum sheath is one of the important factors affecting product quality. Therefore, in the production process of power cables, corresponding shear force tests are required. Specifically, the shear force test refers to the adhesive tensile shear strength test, which is to apply a tensile force parallel to the bonding surface and in the direction of the main axis of the specimen to measure the shear stress at the lap joint of the rigid material.

[0003] In the existing shear force test process, according to the GB / T7124-2008 Determination of tensile shear strength of adhesives (rigid material to rigid material) test standard, the test specimens need to be sampled from the finished cable. In the existing method, the aluminum strip needs to be formed and welded by the aluminum strip forming equipment - the extruder co-extrudes the plastic and hot melt adhesive in two layers to complete the preparation of the specimen.

[0004] The disadvantage of the existing sample preparation method is that the existing sample preparation process is time-consuming and labor-intensive, requiring a large amount of equipment and molds, and at least 2 days of preparation time. At the same time, after the sample is made, other auxiliary work such as machine cleaning is required, which takes at least another day. Therefore, the preparation method of double-layer co-extrusion of hot melt adhesive is very cumbersome and inefficient. Summary of the invention

[0005] To this end, the technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a sample preparation device and a sample preparation method for shear force testing. The sample preparation method of the present invention is easier to operate, has simple steps, can save sample preparation time, greatly improves sample preparation efficiency, and does not require an extruder to prepare the test sample required for the shear force test, thereby saving material costs, startup costs and labor costs.

[0006] In order to solve the above technical problems, the present invention provides a sample preparation device for shear force test, which is used to prepare test samples for shear force test of high-voltage power cables. The sample preparation device comprises: A first cover plate having a first groove thereon; A second cover plate is provided with a second groove, the depth of the second groove is greater than the depth of the first groove; when preparing a sample, the second cover plate covers the first cover plate, the surface where the first groove is located is opposite to the surface where the second groove is located, the first groove and the second groove are staggered with each other, and part of the first groove and part of the second groove overlap in the thickness direction to form a connecting portion, and the first groove and the second groove are connected to each other through the connecting portion; the size of the connecting portion is consistent with the size of the shearing area required by the standard; A positioning member is arranged on the first cover plate or the second cover plate, and the other of the first cover plate or the second cover plate is provided with a positioning hole matching the positioning member, and the positioning member cooperates with the positioning hole to position the first cover plate and the second cover plate relative to each other.

[0007] In one embodiment of the present invention, the first groove is arranged along the length direction of the first cover plate and is close to one end of the first cover plate along the length direction; the second groove is arranged along the length direction of the second cover plate and is close to the other end of the second cover plate along the length direction; the projection of the second groove along the thickness direction of the second cover plate is consistent with the projection of the first groove along the thickness direction of the first groove.

[0008] In one embodiment of the present invention, the projection shapes of the first cover plate and the second cover plate along the thickness direction are consistent.

[0009] In one embodiment of the present invention, the positioning member includes four positioning pins arranged at both ends of the diagonal of the first cover plate, and the positioning hole is arranged at a position opposite to the positioning pin on the second cover plate. The positioning pin can be inserted into the positioning hole to position the first cover plate and the second cover plate relative to each other.

[0010] In one embodiment of the present invention, the projection length of the connecting portion along the thickness direction of the sample preparation device is 25 mm, and the width is 12.5 mm.

[0011] The present invention also provides a sample preparation method for shear force testing, using the sample preparation device for shear force testing as described above to prepare samples required for shear force testing of smooth aluminum sheathed high-voltage power cables, the sample preparation method comprising: Step S1, obtaining a plurality of aluminum strips of the same size, wherein the thickness of the aluminum strips is the same as the depth of the first groove of the sample preparation device; Step S2, taking two of the aluminum strips, namely the first aluminum strip and the second aluminum strip, and preheating the first aluminum strip, the second aluminum strip and the sample preparation device to raise the temperature of the first aluminum strip, the second aluminum strip and the sample preparation device to 190-220°; Step S3, placing the preheated first aluminum strip in the first groove of the sample preparation device, and placing the preheated second aluminum strip in the second groove of the sample preparation device; Step S4, placing glue on the surface of one end of the first aluminum strip close to the connecting portion, and after the glue melts, buckling the first cover plate and the second cover plate together, and fixing the first cover plate and the second cover plate to each other through a positioning member; Step S5, pressurizing the first cover plate and the second cover plate after being fastened together, forming a sample that meets the shear force test requirements after pressurizing for a specified time, opening the first cover plate and the second cover plate, and taking out the sample that meets the shear force test requirements.

[0012] In one embodiment of the present invention, in the step S1, the aluminum strip is obtained by cutting, and the cross-sectional dimension of the aluminum strip is the same as the cross-sectional dimension of the first groove.

[0013] In one embodiment of the present invention, in the step S2, the aluminum strip and the sample preparation device are heated by a flat-plate vulcanizer.

[0014] In one embodiment of the present invention, in the step S5, the first cover plate and the second cover plate are pressurized by a flat-plate vulcanizing machine.

[0015] In one embodiment of the present invention, in step S5, after taking out the sample, the glue overflowing from the sample is removed.

[0016] The above technical solution of the present invention has the following advantages compared with the prior art: The sample preparation device for shear force test of the present invention is provided with a first cover plate, a second cover plate and a positioning member, the first cover plate is provided with a first groove, the second cover plate is provided with a second groove, the first groove and the second groove are arranged alternately, so that when the first cover plate and the second cover plate are covered, a connecting portion can be formed between the first groove and the second groove, the size of the connecting portion is consistent with the size of the sample required for the test, and the positioning member is used to position and fix the first cover plate and the second cover plate to ensure the stability during the sample preparation process. Compared with the prior art, the sample preparation device of the present invention can prepare the test sample required for the shear force test without an extruder, thereby saving material costs, startup costs and labor costs, and the method for sample preparation by the sample preparation device is simple and easy to operate, which can greatly save the sample preparation time, thereby improving the sample preparation efficiency. Further, the effective sample prepared by the sample preparation device simulates the shear strength between the non-metallic sheath and the smooth aluminum sheath, which can truly and effectively reflect the bonding force between the hot melt adhesive and the smooth aluminum sheath; and thus it can also facilitate the rapid selection of hot melt adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0018] Figure 1 It is a structural schematic diagram of the cross section of a smooth aluminum sheathed high-voltage power cable in the prior art.

[0019] Figure 2 It is a schematic structural diagram of the first cover plate of a preferred embodiment of the present invention.

[0020] Figure 3 It is a schematic structural diagram of the second cover plate of a preferred embodiment of the present invention.

[0021] Figure 4 It is a schematic diagram of the overall structure of a sample preparation device according to a preferred embodiment of the present invention.

[0022] Figure 5 It is a schematic cross-sectional structure diagram of the sample preparation device according to the preferred embodiment of the present invention in a fastened state.

[0023] Figure 6 yes Figure 5 Schematic diagram of the front view of the structure in the preferred embodiment with specific dimensions.

[0024] Figure 7 yes Figure 5 Schematic side view of the structure in the preferred embodiment with specific dimensions.

[0025] Explanation of the reference numerals in the specification: 1. first cover plate; 10. first groove; 2. second cover plate; 20. second groove; 3. connecting portion; 40. positioning member; 41. positioning hole. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention. Embodiment 1

[0027] Reference Figure 2-Figure 7 As shown, a sample preparation device for shear force test of the present invention is used to prepare a test sample for a high-voltage power cable for shear force test, and the sample preparation device comprises a first cover plate 1, a first groove 10 is provided on the first cover plate 1, and the first groove 10 is located on the first surface of the first cover plate 1; The sample preparation device for the shear force test further comprises a second cover plate 2 , on which a second groove 20 is provided. The second groove 20 is located on a second surface of the second cover plate 2 .

[0028] Specifically, the depth of the second groove 20 is greater than the depth of the first groove 10; When preparing the sample, it is necessary to place the aluminum strip of the specified specification in the first groove 10 and the second groove 20, and then cover the second cover plate 2 with the first cover plate 1. During the covering process, the first surface is opposite to the second surface. At this time, the first groove 10 and the second groove 20 are staggered with each other, and the projections of part of the first groove 10 and part of the second groove 20 in the thickness direction overlap with each other to form a connecting portion 3. Figure 4 As shown, the first groove 10 and the second groove 20 are connected to each other through the connecting portion 3; It should be noted that the size of the connecting portion 3 is consistent with the size of the shear area required by the standard. The shear area required by the standard refers to the area of ​​the sample that meets the test standard of GB / T7124-2008 Determination of tensile shear strength of adhesives (rigid material to rigid material), so that the connecting portion 3 is used to form a sample that meets the test standard.

[0029] In detail, the sample preparation device for the shear force test also includes a positioning member 40, and the positioning member 40 is arranged on the first cover plate 1 or the second cover plate 2. The other of the first cover plate 1 or the second cover plate 2 is provided with a positioning hole 41 matching the positioning member 40. In this way, the first cover plate 1 and the second cover plate 2 can be positioned relative to each other through the mutual cooperation between the positioning member 40 and the positioning hole 41.

[0030] It can be known from this that the sample preparation device for shear force test to be protected by the present invention is provided with a first cover plate, a second cover plate and a positioning member, the first cover plate is provided with a first groove, the second cover plate is provided with a second groove, the first groove and the second groove are arranged alternately, so that when the first cover plate and the second cover plate are covered, a connecting portion can be formed between the first groove and the second groove, and the size of the connecting portion is consistent with the size of the sample required for the test, and the positioning member is used to position and fix the first cover plate and the second cover plate to ensure the stability during the sample preparation process. Compared with the prior art, the sample preparation device of the present invention can prepare the test sample required for the shear force test without an extruder, thereby saving material costs, startup costs and labor costs, and the method for sample preparation by the sample preparation device is simple and easy to operate, which can greatly save the sample preparation time, thereby improving the sample preparation efficiency. Further, the effective sample prepared by the sample preparation device simulates the shear strength between the non-metallic sheath and the smooth aluminum sheath, which can truly and effectively reflect the bonding effect of the hot melt adhesive between the two; and thus it can also facilitate the rapid selection of hot melt adhesive.

[0031] As a preferred embodiment, the first groove 10 is arranged along the length direction of the first cover plate 1, and the first groove 10 is close to the first end of the first cover plate 1 along the length direction; the second groove 20 is arranged along the length direction of the second cover plate 2, and is close to the other end of the second cover plate along the length direction.

[0032] In detail, a projection of the second groove 20 along the thickness direction of the second cover plate 2 is consistent with a projection of the first groove 10 along the thickness direction of the first groove 1 .

[0033] In this embodiment, the size of the first groove 10 is 100*25*2.0 mm, the size of the second groove 20 is 100*25*2.3 mm, and the depth of the second groove 20 is greater than the depth of the first groove 10, with a difference of 0.3 mm.

[0034] As a preferred embodiment, in order to facilitate operation and ensure that the first cover plate 1 and the second cover plate 2 are subjected to uniform pressing force, the projection shapes of the first cover plate 1 and the second cover plate 2 along the thickness direction are consistent. The length of the first cover plate is 197.5 mm and the width is 45 mm.

[0035] As a preferred embodiment, the positioning member 40 includes four positioning pins disposed at both ends of the diagonal of the first cover plate 1, and the second cover plate 2 is provided with positioning holes 41 at positions opposite to the positioning pins. There are four positioning holes 41, which are respectively located at both ends of the diagonal of the second cover plate 2. In this way, the positioning pins can be inserted into the positioning holes to position the first cover plate 1 and the second cover plate 2 relative to each other.

[0036] As a preferred embodiment, according to Figure 5 As shown, the length of the projection of the connecting portion 3 along the thickness direction of the sample preparation device is 25 mm, the width is 12.5 mm, and the total thickness of the connecting portion 3 is 4.3 mm, which meets the sample size of the test standard of GB / T7124-2008 for the determination of tensile shear strength of adhesives (rigid material to rigid material). During the sample preparation process, the connecting portion 3 will be filled with 2.0 mm thick aluminum strip, 0.3 mm thick hot melt adhesive, and 2.0 mm thick aluminum strip, thereby forming a layer structure of aluminum strip + hot melt adhesive + aluminum strip, which is the prepared sample.

[0037] Of course, in the tests of different types of adhesives, the size of the connecting portion 3 can be adjusted according to actual requirements to adapt to different test requirements.

[0038] From the perspective of actual production, the present invention solves the difficulty of sample preparation when introducing new hot melt adhesive to a certain extent, thereby better promoting users to choose high-quality suppliers of hot melt adhesive for smooth aluminum. Embodiment 2

[0039] The present invention also discloses a sample preparation method for shear force testing, combining Figure 2-Figure 7 As shown, the sample preparation method uses a sample preparation device for shear force test as described in Example 1 to prepare samples required for shear force test of smooth aluminum sheathed high-voltage power cables. The sample preparation method includes: Step S1, obtaining a plurality of aluminum strips of the same size for standby use, wherein the thickness of the aluminum strips is the same as the depth of the first groove 10 of the sample preparation device; Step S2, taking two of the aluminum strips, namely the first aluminum strip and the second aluminum strip, and preheating the first aluminum strip, the second aluminum strip and the sample preparation device to raise the temperature of the first aluminum strip, the second aluminum strip and the sample preparation device to 190-220°; Step S3, placing the preheated first aluminum strip in the first groove 10 of the sample preparation device, and placing the preheated second aluminum strip in the second groove 20 of the sample preparation device; Step S4, placing glue on the surface of one end of the first aluminum strip close to the connecting portion, and after the glue melts, buckling the first cover plate and the second cover plate together, and fixing the first cover plate 1 and the second cover plate 2 to each other through the positioning member 40; Step S5, pressurizing the first cover plate 1 and the second cover plate 2 after being fastened together, and forming a sample that meets the shear force test requirements after pressurizing for a specified period of time, then opening the first cover plate 1 and the second cover plate 2 to take out the sample that meets the shear force test requirements.

[0040] From this, it can be seen that the sample preparation method for shear force test to be protected by the present invention can prepare the test sample required for shear force test without the need for an extruder through mutual cooperation with the preparation device, thereby effectively saving material costs, startup costs and labor costs, and the method steps for sample preparation by the sample preparation device are simple and easy to operate, which can greatly save sample preparation time, thereby improving sample preparation efficiency, and is conducive to the promotion and implementation of subsequent shear force tests.

[0041] As a preferred embodiment, in step S2, the first aluminum strip, the second aluminum strip and the sample preparation device are heated to 200°. Experience from multiple experiments shows that a better preparation effect can be achieved at this temperature.

[0042] As a preferred embodiment, in the step S1, the aluminum strip is obtained by cutting, and the cross-sectional size of the aluminum strip is the same as the cross-sectional size of the first groove 10. Therefore, the aluminum strip can be well embedded in the first groove 10 and the second groove 20 during the sample preparation process, and has high stability.

[0043] In detail, in the step S2, the aluminum strip and the sample preparation device are heated by a flat vulcanizer.

[0044] Furthermore, in the step S5, the first cover plate 1 and the second cover plate 2 are pressurized by a flat-plate vulcanizing machine.

[0045] Furthermore, in the step S5, after taking out the sample, the hot melt glue overflowing from the sample is removed. Embodiment 3

[0046] The present invention also discloses a shear force testing method. First, a sample required for the shear force test is prepared by the sample preparation method described in Example 2; then, a shear force test is performed on the sample to obtain shear force test data of the sample.

[0047] Specifically, the shear force test steps include: Step 1: Clamp the sample symmetrically on the test fixture, with the distance from the clamp to the nearest bonding end being 50 mm ± 1 mm. A gasket can be used in the fixture to ensure that the force is within the bonding surface.

[0048] Step 2: The tensile testing machine is tested at a constant test speed so that the general failure time is between 65s±20s; If the tensile testing machine can load at a constant rate, set the shear force change rate between 8.3MPa and 9.8MPa per minute.

[0049] Step 3: Record the maximum load of shear failure of the specimen as the failure load.

[0050] Result record: The test results are expressed as the arithmetic mean of the breaking load (N) or tensile shear strength (MPa) of the effective specimens. The tensile shear strength (MPa) is calculated by dividing the breaking load (N) by the shear area (mm²).

[0051] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0052] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0053] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0054] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0055] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A sample preparation device for shear force test, used for preparing test samples for shear force test of high voltage power cable, characterized in that: The sample preparation device comprises: A first cover plate having a first groove thereon; A second cover plate is provided with a second groove, the depth of the second groove is greater than the depth of the first groove; when preparing a sample, the second cover plate covers the first cover plate, the surface where the first groove is located is opposite to the surface where the second groove is located, the first groove and the second groove are staggered with each other, and part of the first groove and part of the second groove overlap in the thickness direction to form a connecting portion, and the first groove and the second groove are connected to each other through the connecting portion; the size of the connecting portion is consistent with the size of the shearing area required by the standard; A positioning member is arranged on the first cover plate or the second cover plate, and the other of the first cover plate or the second cover plate is provided with a positioning hole matching the positioning member, and the positioning member cooperates with the positioning hole to position the first cover plate and the second cover plate relative to each other.

2. A sample preparation device for shear force testing according to claim 1, characterized in that: The first groove is arranged along the length direction of the first cover plate and is close to one end of the first cover plate along the length direction; the second groove is arranged along the length direction of the second cover plate and is close to the other end of the second cover plate along the length direction; the projection of the second groove along the thickness direction of the second cover plate is consistent with the projection of the first groove along the thickness direction of the first groove.

3. A sample preparation device for shear force testing according to claim 1, characterized in that: The projection shapes of the first cover plate and the second cover plate along the thickness direction are consistent.

4. A sample preparation device for shear force testing according to claim 1, characterized in that: The positioning member includes four positioning pins arranged at both ends of the diagonal of the first cover plate, and the positioning holes are arranged on the second cover plate at positions opposite to the positioning pins. The positioning pins can be inserted into the positioning holes to position the first cover plate and the second cover plate relative to each other.

5. The sample preparation device for shear force test according to claim 1, characterized in that: The projection length of the connecting portion along the thickness direction of the sample preparation device is 25 mm, and the width is 12.5 mm.

6. A sample preparation method for shear force test, characterized in that: A sample preparation device for shear force testing according to any one of claims 1 to 5 is used to prepare a sample required for shear force testing of a smooth aluminum sheathed high-voltage power cable, and the sample preparation method comprises: Step S1, obtaining a plurality of aluminum strips of the same size, wherein the thickness of the aluminum strips is the same as the depth of the first groove of the sample preparation device; Step S2, taking two of the aluminum strips, namely the first aluminum strip and the second aluminum strip, and preheating the first aluminum strip, the second aluminum strip and the sample preparation device to raise the temperature of the first aluminum strip, the second aluminum strip and the sample preparation device to 190-220°; Step S3, placing the preheated first aluminum strip in the first groove of the sample preparation device, and placing the preheated second aluminum strip in the second groove of the sample preparation device; Step S4, placing glue on the surface of one end of the first aluminum strip close to the connecting portion, and after the glue melts, buckling the first cover plate and the second cover plate together, and fixing the first cover plate and the second cover plate to each other through a positioning member; Step S5, pressurizing the first cover plate and the second cover plate after being fastened together, forming a sample that meets the shear force test requirements after pressurizing for a specified time, opening the first cover plate and the second cover plate, and taking out the sample that meets the shear force test requirements.

7. A sample preparation method for shear force test according to claim 6, characterized in that: In the step S1, the aluminum strip is obtained by cutting, and the cross-sectional dimension of the aluminum strip is the same as the cross-sectional dimension of the first groove.

8. A sample preparation method for shear force test according to claim 6, characterized in that: In the step S2, the aluminum strip and the sample preparation device are heated by a flat-plate vulcanizing machine.

9. A sample preparation method for shear force test according to claim 6, characterized in that: In the step S5, the first cover plate and the second cover plate are pressurized by a flat-plate vulcanizing machine.

10. A sample preparation method for shear force test according to claim 6, characterized in that: In the step S5, after taking out the sample, the glue overflowing from the sample is removed.

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