A method for testing the impact and extrusion resistance of mining cables

Abstract

The present invention discloses a method for testing the impact resistance and extrusion of mining cables, which sets 5 test points on a cable sample according to the twisted pitch of the inner core of the cable, wherein the first test point is set at the middle position of the cable sample in the axial direction, the second test point and the third test point are symmetrically distributed on both sides of the first test point, and are respectively separated from the first test point by a twisted pitch of the inner core of the cable, and the second test point, the third test point and the first test point differ by 120° in the circumferential direction of the cable sample; the fourth test point and the fifth test point are symmetrically distributed on both sides of the first test point, and the fourth test point, the fifth test point and the first test point differ by 0° in the circumferential direction of the cable sample. The method has accurate measurement results and can effectively overcome the problems existing in the prior art.

Description

Technical Field

[0001] The invention relates to a cable testing technology, in particular to an impact resistance and extrusion testing technology for mining cables. Background Art

[0002] The relevant performance tests for mining cables mainly involve two aspects: impact resistance and extrusion tests of mining cables.

[0003] (1) Mechanical shock resistance test

[0004] The mechanical impact test of mining cables is carried out on a free-fall impact test machine. The hammer mass and stroke are selected according to the requirements in Table 1.

[0005] Table 1 Hammer mass and stroke

[0006]

[0007] like Figure 1 As shown, during the specific test, a sample 2 of about 2m in length is cut from the finished cable, installed on the testing machine, and placed on the bearing plate 3 of the testing machine. At the same time, a three-phase AC rated voltage is applied between the power cores of the sample 2 (a voltage of 0.66 / 1.14kV is applied to cables with a rated voltage of 0.66 / 1.14kV or above), and a leakage detection relay is connected.

[0008] Based on this setting, start the testing machine, and the hammer 1 falls freely from the specified height to impact the cable sample 2; the same sample should be tested at 5 locations respectively, and the distance between two adjacent locations is about 100mm.

[0009] (2) Anti-extrusion test

[0010] The test should be carried out on a hydraulic press or a Figure 2 The test was carried out on a test device composed of an extrusion die shown in FIG. The extrusion die consists of a steel rail 4 (width a=70 mm) and an iron upper pressing plate 5.

[0011] Cut a section of sample 2 about 2 m long from the finished cable and install it in the extrusion die. Figure 2 shown.

[0012] On this basis, apply three-phase AC rated voltage (rated voltage 0.66 / 1.14kV or above, applied voltage 0.66 / 1.14kV) between each power line core of the sample, and connect the leakage detection relay. Start the pressure plate, slowly increase the pressure to the specified value, and maintain it for 1 second. According to the test requirements, the same sample should be tested at 5 locations, with the distance between two adjacent locations being about 100mm. The press machine must have the function of setting the pressure value, and the pressure value error shall not exceed ±1% of the specified value.

[0013] When testing the relevant performance of mining cables based on the above-mentioned existing mining cable impact and extrusion test scheme, the same sample should be tested at 5 locations, and the distance between two adjacent locations is about 100mm. In actual operation, this test method cannot meet the reliability requirements of the impact and extrusion performance of the tested wire core. Summary of the invention

[0014] In view of the problem that the existing cable impact and extrusion test scheme cannot meet the reliability of the wire core measurement results, the purpose of the present invention is to provide a mining cable impact and extrusion test method, which can effectively improve the accuracy of the wire core impact and extrusion performance test measurement results.

[0015] In order to achieve the above-mentioned purpose, the present invention provides a method for testing the impact and extrusion resistance of mining cables. The method sets 5 test points on the cable sample according to the twisted pitch of the inner core of the cable, wherein the first test point is set at the middle position of the cable sample in the axial direction, the second test point and the third test point are symmetrically distributed on both sides of the first test point, and are respectively separated from the first test point by a twisted pitch of the inner core of the cable, and the second test point, the third test point and the first test point are each 120° apart in the circumferential direction of the cable sample;

[0016] The fourth test point and the fifth test point are symmetrically distributed on both sides of the first test point, and the fourth test point, the fifth test point and the first test point differ by 0° in the circumferential direction of the cable sample.

[0017] Further, in the test method, if the cabling pitch of the tested mining cable is greater than 200 mm, the fourth test point and the fifth test point are respectively distributed between the second test point and the first test point, and between the third test point and the first test point;

[0018] If the cabling pitch of the tested mining cable is less than 200 mm, the fourth test point and the fifth test point are respectively distributed outside the second test point and the third test point.

[0019] Furthermore, the test method first performs test measurement on a first test point on the cable sample; after completing the measurement of the first test point, then performs test measurement on a second test point or a third test point; and finally performs test measurement on a fourth test point or a fifth test point.

[0020] Furthermore, the test method uses a rotatable clamp to fix both ends of the cable sample, and can drive the cable sample to rotate along its axial direction.

[0021] The impact resistance and extrusion test method for mining cables provided by the present invention respectively tests the same sample at 5 test points based on different cable twisting pitches, and conducts tests at different angles, effectively realizing the state of the wire core in the 360° direction of the entire cross-section of the cable after being impacted and extruded by external forces, thereby effectively improving the accuracy of the measurement results of the impact resistance and extrusion resistance test of the wire core.

[0022] When the impact and extrusion test method for mining cables provided by the present invention is implemented, the same sample needs to be rotated three times, each rotation is 120°. At the same time, the corresponding impact extrusion device itself has a certain width. During the extrusion impact test, the contact surface width is greater than the circumference of the cable in the 120° direction of the cable. As a result, the wire cores in 360 directions can be impacted and extruded, thereby meeting the accuracy of the wire core measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0024] Figure 1 This is an example diagram of the mechanical impact resistance test of existing mining cables;

[0025] Figure 2 This is an example diagram of the existing mining cable anti-extrusion test;

[0026] Figure 3 This is an example diagram of measuring the twist pitch of the inner core of a cable in an example of the present invention;

[0027] Figure 4 This is an example diagram of a mining cable extrusion test platform in an example of the present invention;

[0028] Figure 5 This is an example diagram of a mining cable impact test platform in an example of the present invention;

[0029] Figure 6 This is an example diagram of the distribution of the test points along the circumference of the cable sample in the example of the present invention;

[0030] Figure 7 This is an example diagram of the distribution of the test points along the axial direction of the cable sample when the cabling pitch (h) is greater than 200 mm in an example of the present invention;

[0031] Figure 8 This is an example diagram of the distribution of test points along the circumference of the cable sample when the cabling pitch (h) is less than 200 mm in an example of the present invention. DETAILED DESCRIPTION

[0032] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below with reference to specific diagrams.

[0033] In this example, when conducting impact and extrusion tests on mining cables, the twist pitch of the inner core of the cable is innovatively measured, and the test points are set based on the twist pitch of the inner core of the cable, thereby improving the accuracy of the measurement results.

[0034] See also Figure 3 In this example, the cable twist pitch is first measured before the impact extrusion test to prepare for subsequent tests. As shown in the figure, the cable core twist pitch h here is specifically the distance that a single wire moves forward along the stranded wire axis when it rotates one circle.

[0035] Since the insulated core inside the cable is twisted, the twisting pitch of different cables is different; moreover, the cross-sectional structure of the cable at the same twisting pitch h is exactly the same.

[0036] Thus, the solution of the present application innovatively sets the distribution of relevant test points based on the "twisting pitch h". In this way, through the rotation test, the starting point on the axial direction is the same, that is, the test is carried out after rotating 120° from the same point. This can fully ensure that 360° directions will be detected during the test. Compared with the existing impact extrusion test method, this solution can fully take every position into consideration.

[0037] This example also needs to further build corresponding cable impact test platform and cable extrusion test platform to test the impact resistance and extrusion resistance of mining cables.

[0038] See also Figure 4 , which shows an example of a cable extrusion test platform constructed in this example.

[0039] As can be seen from the figure, the cable extrusion test platform 10 is mainly composed of a cable clamp 11, a pressing plate 12, and a steel rail 13.

[0040] The cable clamp 11 is used to fix the cable sample 30 and can drive the cable sample 30 to rotate along its axial direction.

[0041] Specifically, the cable clamp 11 here is mainly composed of a corresponding rotatable fixed clamp and a corresponding rotatable device. The rotatable fixed clamp is fixedly arranged at both ends of the cable sample 30 to fix the cable sample 30, and the rotatable device can simultaneously drive the rotatable fixed clamps arranged at both ends of the cable sample 30 to rotate synchronously, thereby driving the cable sample 30 to rotate along its axial direction, so as to adjust different test positions on the cable sample 30 to cooperate with the pressure plate 12 and the rail 13 for corresponding tests.

[0042] The specific configuration of the rotatable fixed chuck and the rotatable device is not limited here and can be determined according to actual needs.

[0043] Furthermore, the pressing plate 12 in the cable extrusion test platform 10 cooperates with the steel rail 13 to simulate the extrusion test environment. Specifically, the pressing plate 12 is an iron pressing plate and is placed above the steel rail 13, so that an extrusion test area is formed between the two, and the cable sample 30 can be placed therein to simulate the extrusion test environment.

[0044] Furthermore, the cable extrusion test platform 10 is also equipped with corresponding test voltage and leakage detection relay to measure the cable sample 30 in the test state.

[0045] The test voltage here adopts the three-phase AC rated voltage, such as applying 0.66 / 1.14kV voltage to the cable with rated voltage above 0.66 / 1.14kV. In this way, after the cable sample 30 is installed on the test bench, the three-phase AC rated voltage is applied between the power cores of the sample, and the leakage detection relay is connected to measure the cable sample 30 in the test state.

[0046] See also Figure 5 , which shows an example of the cable impact test platform constructed in this example.

[0047] As can be seen from the figure, the cable extrusion test platform 20 is mainly composed of a cable clamp 21, a hammer 22, and a support plate 23.

[0048] The cable clamp 21 is used to fix the cable sample 30 and can drive the cable sample 30 to rotate along its axial direction.

[0049] Specifically, the cable clamp 21 here is mainly composed of a corresponding rotatable fixed chuck and a corresponding rotatable device. The rotatable fixed chuck is fixedly arranged at both ends of the cable sample 30 to fix the cable sample 30, and the rotatable device can simultaneously drive the rotatable fixed chucks arranged at both ends of the cable sample 30 to rotate synchronously, thereby driving the cable sample 30 to rotate along its axial direction, so as to adjust different test positions on the cable sample 30 to cooperate with the hammer 22 and the support plate 23 to perform corresponding tests.

[0050] The specific configuration of the rotatable fixed chuck and the rotatable device is not limited here and can be determined according to actual needs.

[0051] Furthermore, the hammer 22 in the cable extrusion test platform 10 cooperates with the support plate 23 to simulate the impact test environment. Specifically, the hammer 22 is determined according to the test requirements, R=25, L>1.5d. The support plate 23 is an iron pressure plate and is placed under the hammer 22, so that a stamping test area is formed between the two, and the cable sample 30 can be placed therein to simulate the stamping test environment.

[0052] Furthermore, the cable extrusion test platform 20 is also equipped with corresponding test voltage and leakage detection relay to measure the cable sample 30 in the test state.

[0053] The test voltage here adopts the three-phase AC rated voltage, such as applying 0.66 / 1.14kV voltage to the cable with rated voltage above 0.66 / 1.14kV. In this way, after the cable sample 30 is installed on the test bench, the three-phase AC rated voltage is applied between the power cores of the sample, and the leakage detection relay is connected to measure the cable sample 30 in the test state.

[0054] Based on the aforementioned cable inner core twist pitch measurement and the related cable impact test platform and cable extrusion test platform, the implementation process of the impact and extrusion test on the mining cable in this example is as follows.

[0055] First, a sample of about 2m in length is cut from the finished cable. The preparation of the sample terminal should ensure that no flashover along the surface and internal breakdown will occur under the specified voltage.

[0056] Next, the test points of the obtained cable samples are marked.

[0057] In order to fully and accurately reflect the performance of the cable, it is preferred to mark 5 groups of test points on the cable sample for impact and extrusion tests.

[0058] In this example, the test points are marked based on the measured twist pitch of the cable core.

[0059] Specifically, in this example, whether the twist pitch of the cable core is greater than 200mm is used as the basis for adjusting the test point marking. In this way, the determined test points can fully and effectively reflect the state of the cable core in the 360° direction of the entire section after being impacted and squeezed by external forces, thereby ensuring the accuracy of the test results.

[0060] See also Figure 7 When the cabling pitch (h) is greater than 200mm, the first test point 1 is set in the middle position of the cable sample 30 in the axial direction, the second test point 2 and the third test point 3 are symmetrically distributed on both sides of the first test point 1, and the distance between the second test point 2 and the first test point 1 is the twisted pitch h of the cable inner core, and the distance between the third test point 3 and the first test point 1 is the twisted pitch h of the cable inner core.

[0061] See also Figure 8 At the same time, the second test point 2, the third test point 3 and the first test point 1 are equally spaced in the circumferential direction of the cable specimen, and the difference between the three is 120°.

[0062] The fourth test point 4 and the fifth test point 5 are symmetrically distributed on both sides of the first test point 1, and the fourth test point 4 is 100 mm away from the first test point 1, and the fifth test point 5 is 100 mm away from the first test point 1. At the same time, the fourth test point 4, the fifth test point 5 and the first test point 1 differ by 0° in the circumferential direction of the cable sample 30, that is, the fourth test point 4, the fifth test point 5 and the first test point 1 are distributed along a straight line in the axial direction of the cable sample 30.

[0063] When the twisted pitch is greater than 200mm, the above test point distribution test plan is adopted. The second test point 1 is used in conjunction with the second test point 2 and the third test point 3 to fully ensure that the wire cores in the entire cable section are detected; on this basis, the fourth test point 4 and the fifth test point 5 are used to implement the test on the inner side of the pitch, which can further increase the comprehensiveness and severity of the test. Through 5 short-distance impact tests, the performance of the cable can be fully and accurately detected.

[0064] See also Figure 6 When the cabling pitch (h) is less than 200mm, the first test point 1 is set in the middle position of the cable sample 30 in the axial direction, the second test point 2 and the third test point 3 are symmetrically distributed on both sides of the first test point 1, and the distance between the second test point 2 and the first test point 1 is the twisted pitch h of the cable inner core, and the distance between the third test point 3 and the first test point 1 is the twisted pitch h of the cable inner core.

[0065] See also Figure 8 At the same time, the second test point 2, the third test point 3 and the first test point 1 are equally spaced in the circumferential direction of the cable specimen, and the difference between the three is 120°.

[0066] The fourth test point 4 and the fifth test point 5 are symmetrically distributed on both sides of the first test point 1. Specifically, the fourth test point 4 is distributed on the outside of the second test point 2 (i.e., the side away from the first test point 1), and the fifth test point 5 is distributed on the outside of the third test point 3 (i.e., the side away from the first test point 1); and the fourth test point 4 is 100 mm away from the second test point 2, and the fifth test point 5 is 100 mm away from the third test point 3. At the same time, the fourth test point 4, the fifth test point 5 and the first test point 1 differ by 0° in the circumferential direction of the cable sample 30, that is, the fourth test point 4, the fifth test point 5 and the first test point 1 are distributed along a straight line in the axial direction of the cable sample 30.

[0067] When the twist pitch is less than 200mm, the above test point distribution test plan is adopted to achieve comprehensive and accurate detection of cable performance.

[0068] Next, for the cable samples with the test points marked, the cables are placed in the cable impact test platform and the cable extrusion test platform respectively, and the cable impact test platform and the cable extrusion test platform respectively perform impact and extrusion tests on five different test points on the cable samples.

[0069] For each test in this step, the same cable sample should be tested at 5 locations.

[0070] Specifically, when the impact test is performed on the cable sample, the cable sample with the test point marked is placed in the cable impact test platform, and the three-phase AC rated voltage is applied between the power cores of the sample, and the leakage detection relay is connected to measure the cable sample in the test state (such as Figure 5 shown).

[0071] At that time, the first test point 1 on the cable sample is facing the hammer 22 in the cable impact test platform, and the hammer 22 is released through the platform, so that the hammer 22 hits the first test point 1 on the cable sample based on its own gravity. In this process, the change state of the current and voltage in the cable sample when it is hit by the hammer 22 is synchronously detected, and the data is recorded, thereby completing the test measurement for the first test point 1;

[0072] After completing the test measurement of the first test point 1, the hammer 22 is raised, and the cable sample is driven to rotate 120° along its axial direction through the rotatable fixture, so that the second test point 2 faces the hammer 22 in the cable impact test platform, and then the hammer 22 is released through the platform, so that the hammer 22 hits the second test point 2 on the cable sample based on its own gravity. In this process, the change state of the current and voltage in the cable sample when it is hit by the hammer 22 is synchronously detected, and the data is recorded, thereby completing the test measurement for the second test point 2;

[0073] Based on the same steps, the test measurements of the third test point 3, the fourth test point 4, and the fifth test point 5 are completed in sequence.

[0074] It should be noted here that during the test process, the test order of the second test point 2 and the third test point 3 can be swapped; and the test order between the fourth test point 4 and the fifth test point 5 can be swapped; but the tests of the second test point 2 and the third test point 3 need to be completed first.

[0075] In this way, the impact resistance test of mining cables is completed and accurate measurement results are obtained, which can accurately detect the impact resistance performance of mining cables.

[0076] When the cable sample is subjected to the extrusion test, the cable sample with the test point marked is placed in the cable impact test platform. At the same time, the three-phase AC rated voltage is applied between the power cores of the sample, and the leakage detection relay is connected to measure the cable sample in the test state (such as Figure 4 shown).

[0077] At that time, the first test point 1 on the cable sample is facing the pressure plate 12 in the cable impact test platform. At that time, the pressure plate 12 is activated through the platform, so that the pressure plate 12 abuts against the first test point 1 on the cable sample, and after abutting against the first test point 1 on the cable sample, the pressure is slowly increased to the specified value and maintained for 1 second. In this process, the change state of the current and voltage in the cable sample when it is squeezed by the pressure plate 12 is synchronously detected, and the data is recorded, thereby completing the squeeze test measurement for the first test point 1;

[0078] After completing the test measurement of the first test point 1, lift the pressure plate 12, and drive the cable sample to rotate 120° along its axis through the rotatable clamp, so that the second test point 2 faces the pressure plate 12 in the cable impact test platform. Then start the pressure plate 12 through the platform, so that the pressure plate 12 abuts the second test point 2 on the cable sample, and after abutting the second test point 2 on the cable sample, slowly increase the pressure to the specified value and maintain it for 1 second. In this process, the current and voltage changes in the cable sample when it is squeezed by the pressure plate 12 are synchronously detected, and data is recorded, thereby completing the squeeze test measurement for the second test point 2;

[0079] Based on the same steps, the extrusion test measurements of the third test point 3, the fourth test point 4, and the fifth test point 5 are completed in sequence.

[0080] It should be noted here that during the test process, the test order of the second test point 2 and the third test point 3 can be swapped; and the test order between the fourth test point 4 and the fifth test point 5 can be swapped; but the tests of the second test point 2 and the third test point 3 need to be completed first.

[0081] In this way, the anti-extrusion test of mining cables is completed and accurate measurement results are obtained, which can be used for mining cables.

[0082] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. The impact and extrusion test method for mining cables is characterized by: The test method sets 5 test points on the cable sample according to the twisted pitch of the inner core of the cable, wherein the first test point is set at the middle position of the cable sample in the axial direction, the second test point and the third test point are symmetrically distributed on both sides of the first test point, and are respectively separated from the first test point by a twisted pitch of the inner core of the cable, and the second test point, the third test point and the first test point are 120° apart in the circumferential direction of the cable sample; The fourth test point and the fifth test point are symmetrically distributed on both sides of the first test point, and the fourth test point, the fifth test point and the first test point differ by 0° in the circumferential direction of the cable sample; In the test method, if the cabling pitch of the tested mining cable is greater than 200 mm, the fourth test point and the fifth test point are respectively distributed between the second test point and the first test point, and between the third test point and the first test point; If the cabling pitch of the tested mining cable is less than 200 mm, the fourth test point and the fifth test point are respectively distributed outside the second test point and the third test point.

2. The impact and extrusion test method for mining cables according to claim 1, characterized in that: The test method first performs test measurement on the first test point on the cable sample; after completing the measurement of the first test point, then performs test measurement on the second test point or the third test point; finally, performs test measurement on the fourth test point or the fifth test point.

3. The impact and extrusion test method for mining cables according to claim 1, characterized in that: The test method adopts a rotatable clamp to fix both ends of the cable sample and can drive the cable sample to rotate along its axial direction.

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