Cable tensile strength testing device

Abstract

The invention belongs to the technical field of electrics, and particularly relates to a cable tensile strength testing device which comprises a testing platform; the cable testing device comprises a testing platform, two groups of inner side clamping mechanisms are symmetrically distributed above the testing platform and used for clamping and fixing a cable from the inner side of the cable, each inner side clamping mechanism comprises a supporting disc, the center position of each supporting disc is rotatably connected with a first lead screw, and each first lead screw is in threaded connection with a movable sleeve. The detection reliability is improved through internal and external cooperative clamping, the inner side clamping mechanism drives multiple sets of clamping plates to synchronously contract centripetally through a first lead screw, the outer side clamping mechanism adjusts the clamping force through the magnetic field intensity by means of the rheological characteristic of magnetorheological fluid, the outer side clamping mechanism flexibly wraps the outer wall of a cable, the clamping force is guaranteed, skin damage is avoided, and the detection efficiency is improved. The stress of the cable in the stretching process is more uniform, and the detection data is closer to the real tensile strength.

Description

Technical Field

[0001] The invention belongs to the field of electrical technology, and in particular relates to a cable tensile strength testing device. Background Art

[0002] A cable is a conductor consisting of one or more mutually insulated conductors covered by a protective layer (such as a sheath, shielding layer, and insulation layer). It is primarily used to transmit electrical energy, electrical signals, or convert electromagnetic energy. During cable installation (such as overhead, underground pipeline traction, and underwater installation), it is subject to tensile forces. For example, overhead cables must withstand their own weight, wind loads, ice, and snow loads. If their tensile strength is insufficient, they may break due to excessive stretching during installation or use. Therefore, after cable production, they must undergo tensile strength testing.

[0003] However, the existing testing devices still have the following technical problems when testing the tensile strength of cables:

[0004] 1. Single clamping method and insufficient test accuracy: Traditional cable tensile strength testers often use a single external clamping structure, such as a mechanical clamp or hydraulic clamp. This method can easily lead to uneven stress on the cable, especially for cables with complex internal twisting structures. Clamping can cause localized stress concentration, causing the tensile strength test data to deviate from the actual value.

[0005] 2. Lack of pre-flattening function: Existing devices often lack an automated mechanism for flattening the cable before tensile testing. Cables are prone to bending and wrinkling during storage or transportation. If tested directly, the irregular initial shape will lead to uneven tensile force transmission, affecting the accurate measurement of breaking strength.

[0006] 3. Inconvenient clamping force adjustment and poor adaptability: Although some devices have clamping force adjustment functions, they often use mechanical knobs or fixed gears, making it difficult to accurately match cables of different diameters and materials (such as high-voltage cables and flexible cables). When testing cables of different specifications, the fixture needs to be frequently changed, which is cumbersome and inefficient. Summary of the Invention

[0007] The purpose of the present invention is to address the problems raised in the above background technology and provide a cable tensile strength testing device that improves detection reliability through internal and external collaborative clamping, makes the cable more evenly stressed during the stretching process, and makes the detection data closer to the actual tensile strength.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A cable tensile strength testing device, comprising:

[0010] test platform;

[0011] An inner clamping mechanism, wherein the inner clamping mechanism is provided with two groups and symmetrically distributed above the test platform, and is used to clamp and fix the cable from the inner side thereof, and the inner clamping mechanism comprises a supporting disc, a first screw rod is rotatably connected to the center position of the supporting disc, a movable sleeve is threadedly connected to the first screw rod, a plurality of first hinge seats distributed in a circumferential array are provided on the movable sleeve, a plurality of clamping plates distributed in a circumferential array are linearly slidably connected to the supporting disc, a second hinge seat is provided on each clamping plate, a connecting rod is hinged between the first hinge seat and the second hinge seat at the corresponding position, and a first motor for driving the connecting rod is fixedly connected to the side of the supporting disc away from the first screw rod;

[0012] An outer clamping mechanism is used to clamp and fix the cable from the outside;

[0013] The flattening mechanism is used to flatten the cable before stretching it, so as to accurately detect the tensile strength of the cable.

[0014] Preferably, a limiting rod is fixedly connected to a side wall of the support disc close to the movable sleeve, and the movable sleeve moves linearly along the limiting rod.

[0015] Preferably, the outer clamping mechanism includes a fixed ring fixedly connected to the side wall of the support disc, a tightening elastomer fixedly connected to the inner wall of the fixed ring, a liquid storage tank fixedly connected to the outer wall of the fixed ring, a piston plate sealingly and slidingly connected to the inside of the liquid storage tank, a return spring is provided between the piston plate and the inside of the liquid storage tank, a first electromagnet is fixedly connected to the inner wall of the liquid storage tank away from the return spring, a magnetic sheet is provided on the side of the piston plate close to the first electromagnet, and when the first electromagnet is energized, it repels the same pole of the magnetic sheet, and the magnetic repulsion force is greater than the elastic force of the return spring.

[0016] Preferably, a connecting groove connected to the liquid storage tank and the tightening elastic body is provided on the fixing ring, and a liquid storage space is formed between the space on one side of the liquid storage tank close to the tightening elastic body, the connecting groove and the inside of the tightening elastic body, and the liquid storage space is filled with magnetorheological fluid.

[0017] Preferably, an excitation coil for controlling the magnetic field strength around the magnetorheological fluid is provided in the tightening elastic body.

[0018] Preferably, the paving mechanism includes a supporting platform fixedly connected to the upper end of the test platform, two symmetrically arranged moving blocks are linearly slidably connected to the supporting platform, the upper end of the moving block is fixedly connected to a control track, a stretching block is provided in the control track, and the stretching block is fixedly connected to the supporting disc at the corresponding position, and two fixed blocks are fixedly connected to the supporting platform, and a second screw rod is rotatably connected between the two fixed blocks, and threads with opposite spiral directions are provided on both sides of the rod body of the second screw rod, and the threads on both sides of the second screw rod are respectively threadedly connected to the two moving blocks, and a second motor for driving the second screw rod is fixedly connected to one of the fixed blocks.

[0019] Preferably, a limiting groove is provided on the control track, and the stretching block is slidably connected to the inner wall of the limiting groove.

[0020] Preferably, a compression spring is provided between the stretching block and the side wall of the corresponding control track, and a second electromagnet is provided on the side wall of the stretching block and the control track away from the compression spring. When the two second electromagnets are energized, opposite poles attract each other, and the magnetic attraction force is greater than the elastic force of the compression spring.

[0021] Compared with existing technologies, the advantages of this cable tensile strength test device are:

[0022] 1. The present invention improves detection reliability through internal and external coordinated clamping. Specifically, the inner clamping mechanism drives multiple groups of clamping plates to contract synchronously and centripetally through the first screw, achieving uniform clamping from the inner wall of the cable and avoiding the eccentricity problem of traditional outer clamping. The outer clamping mechanism utilizes the rheological properties of magnetorheological fluid to adjust the clamping force through the magnetic field strength, flexibly wrapping the outer wall of the cable, ensuring the clamping force while avoiding damage to the epidermis, so that the cable is subjected to more uniform force during the stretching process, and the detection data is closer to the actual tensile strength.

[0023] 2. The present invention eliminates the initial shape error by setting a flattening mechanism, and drives the supporting discs on both sides to stretch the cable horizontally through the second screw and the two-way thread design. The composite structure of the compression spring and the second electromagnet is used to achieve the graded flattening of "buffered pre-stretching-strong shaping", ensuring that the cable is in a straight state before testing, eliminating the interference of bending and wrinkles on the transmission of tensile force, and improving the detection accuracy by more than 30%.

[0024] 3. This invention utilizes dynamic magnetorheological fluid adjustment to accommodate a wide range of cable sizes. The outer clamping mechanism, through coordinated control of the excitation coil and the first electromagnet, adjusts the viscosity of the magnetorheological fluid in real time, thereby providing stepless adjustment of the clamping force. Whether it's a thin cable with a diameter of 5mm or a high-voltage cable of 100mm, precise clamping can be achieved through magnetic field parameter settings, eliminating the need for fixture replacement and improving adaptability by 80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the three-dimensional structure of a cable tensile strength testing device provided by the present invention;

[0026] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0027] Figure 3 This is a partial structural diagram of a cable tensile strength testing device provided by the present invention;

[0028] Figure 4 yes Figure 3 Enlarged view of point B in the middle;

[0029] Figure 5 It is a partial cross-sectional view of a liquid storage tank in a cable tensile strength testing device provided by the present invention;

[0030] Figure 6 yes Figure 5 Enlarged view of point C in the middle.

[0031] In the figure: 1. test platform; 2. inner clamping mechanism; 21. support disc; 22. first screw rod; 23. movable sleeve; 24. first hinge seat; 25. clamping plate; 26. second hinge seat; 27. connecting rod; 28. first motor; 3. outer clamping mechanism; 31. fixing ring; 32. tightening elastomer; 33. liquid storage tank; 34. piston plate; 35. return spring; 36. first electromagnet; 4. leveling mechanism; 41. support platform; 42. moving block; 43. control track; 44. stretching block; 45. fixed block; 46. second screw rod; 47. second motor; 5. limit rod; 6. limit groove; 7. compression spring; 8. second electromagnet. DETAILED DESCRIPTION

[0032] The following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0033] Example: Refer to Figures 1 to 6 , a cable tensile strength testing device, comprising:

[0034] Test platform 1;

[0035] The inner clamping mechanism 2 is provided with two groups and symmetrically distributed above the test platform 1, which is used to clamp and fix the cable from the inside. The inner clamping mechanism 2 includes a support disc 21. The center position of the support disc 21 is rotatably connected to a first screw rod 22. A movable sleeve 23 is threadedly connected to the first screw rod 22. The movable sleeve 23 is provided with a plurality of first hinge seats 24 distributed in a circumferential array. A plurality of clamping plates 25 distributed in a circumferential array are linearly slidably connected to the support disc 21. Each clamping plate 25 is provided with a second hinge seat 26. A connecting rod 27 is hinged between the first hinge seat 24 and the second hinge seat 26 at the corresponding position. A first motor 28 for driving the connecting rod 27 is fixedly connected to the side of the support disc 21 away from the first screw rod 22;

[0036] Specifically, a limiting rod 5 is fixedly connected to a side wall of the support disc 21 close to the movable sleeve 23, and the movable sleeve 23 moves linearly along the limiting rod 5, ensuring that the movable sleeve 23 only moves axially, avoiding circumferential rotation of the sleeve due to the rotation of the screw, and ensuring that the clamping plate 25 opens and closes synchronously and stably.

[0037] When the first motor 28 is started, it drives the first screw rod 22 to rotate. Since the movable sleeve 23 is threadedly connected to the first screw rod 22 and the limit rod 5 limits its rotation (only linear movement is allowed), the movable sleeve 23 will move along the limit rod 5. When the movable sleeve 23 moves, the connecting rod 27 is driven to swing through the first hinge seat 24. The second hinge seat 26 at the other end of the connecting rod 27 pushes the clamping plate 25 to slide linearly on the support disc 21. The multiple clamping plates 25 are distributed in a circular array. Therefore, when the movable sleeve 23 moves, the clamping plates 25 gather toward the center and clamp from the inside of the cable; when it moves in the opposite direction, it is released.

[0038] The outer clamping mechanism 3 is used to clamp and fix the cable from the outside. The outer clamping mechanism 3 includes a fixing ring 31 fixedly connected to the side wall of the support disc 21, and a tightening elastomer 32 is fixedly connected to the inner wall of the fixing ring 31. A liquid storage tank 33 is fixedly connected to the outer wall of the fixing ring 31. A piston plate 34 is sealingly and slidingly connected to the inside of the liquid storage tank 33. A return spring 35 is provided between the piston plate 34 and the inside of the liquid storage tank 33. A first electromagnet 36 is fixedly connected to the inner wall of the liquid storage tank 33 away from the return spring 35. A magnetic sheet is provided on the side of the piston plate 34 close to the first electromagnet 36. When the first electromagnet 36 is energized, it repels the same pole of the magnetic sheet, and the magnetic repulsion force is greater than the elastic force of the return spring 35.

[0039] Specifically, a connecting groove connected to the liquid storage tank 33 and the tightening elastic body 32 is opened on the fixing ring 31. A liquid storage space is formed between the space on one side of the liquid storage tank 33 close to the tightening elastic body 32, the connecting groove and the inside of the tightening elastic body 32, and the liquid storage space is filled with magnetorheological fluid.

[0040] Specifically, an excitation coil for controlling the magnetic field strength around the magnetorheological fluid is provided in the tightening elastic body 32 .

[0041] The liquid storage space (composed of the liquid storage tank 33, the connecting groove and the interior of the tightening elastic body 32) is filled with magnetorheological fluid, the viscosity of which can be adjusted by the strength of the magnetic field. When the first electromagnet 36 is energized, it repels the magnetic sheet on the piston plate 34 with the same pole. The magnetic repulsion overcomes the elastic force of the return spring 35, pushing the piston plate 34 toward the inside of the liquid storage tank 33, squeezing the magnetorheological fluid through the connecting groove into the tightening elastic body 32. After the magnetorheological fluid is pressurized, the tightening elastic body 32 expands and contracts inward, applying a clamping force from the outside of the cable; at the same time, the excitation coil in the tightening elastic body can adjust the magnetic field strength and change the viscosity of the magnetorheological fluid, thereby accurately controlling the magnitude of the clamping force. When the power is off, the return spring 35 pushes the piston plate 34 to reset, the magnetorheological fluid flows back, the tightening elastic body 32 returns to its original state, and the cable is released.

[0042] The flattening mechanism 4 is used to flatten the cable before stretching it so as to accurately detect the tensile strength of the cable. The flattening mechanism 4 includes a support platform 41 fixedly connected to the upper end of the test platform 1. Two symmetrically arranged moving blocks 42 are linearly slidably connected to the support platform 41. The upper end of the moving block 42 is fixedly connected to a control track 43. A stretching block 44 is provided in the control track 43. The stretching block 44 is fixedly connected to the support disc 21 at the corresponding position. Two fixed blocks 45 are fixedly connected to the support platform 41. A second screw rod 46 is rotatably connected between the two fixed blocks 45. Threads with opposite spiral directions are provided on both sides of the rod body of the second screw rod 46. The threads on both sides of the second screw rod 46 are respectively threadedly connected to the two moving blocks 42. A second motor 47 for driving the second screw rod 46 is fixedly connected to one of the fixed blocks 45.

[0043] A second motor 47 rotates a second screw 46. Because the threads on the two sides of the screw rotate in opposite directions, the two moving blocks 42 move toward or away from each other along the support platform 41, driving the control rail 43 to move synchronously. The stretching block 44 is fixedly connected to the support disc 21 and slides within the limit slot 6 of the control rail 43. When the moving block 42 moves, the control rail 43 pulls the support discs 21 on both sides through the stretching block 44, stretching the cable horizontally on the test platform 1, eliminating bends or wrinkles and achieving a flat surface.

[0044] Specifically, a limiting groove 6 is provided on the control track 43 , and the stretching block 44 is slidably connected to the inner wall of the limiting groove 6 .

[0045] A compression spring 7 is provided between the stretching block 44 and the side wall of the corresponding control track 43. A second electromagnet 8 is provided on the side wall of the stretching block 44 and the control track 43 away from the compression spring 7. When the two second electromagnets 8 are energized, the opposite poles attract each other, and the magnetic attraction force is greater than the elastic force of the compression spring 7.

[0046] The synergistic effect of the compression spring 7 and the second electromagnet 8:

[0047] When no power is applied, the compression spring 7 pushes the stretching block 44 to the initial position in the limiting groove 6, allowing the cable to have a buffer space in the initial stage of stretching to avoid damage caused by sudden force.

[0048] After power is turned on, the second electromagnet 8 attracts each other with opposite poles, and the magnetic attraction force overcomes the spring force, causing the stretching block 44 to move in the limit groove 6, ensuring that the cable is continuously stretched during the test. When the working power of the second electromagnet 8 is greater, the magnetic attraction force is greater, and the distance between the two stretching blocks 44 is farther away from each other, thereby applying different stretching forces to the cable and realizing the tensile strength test of the cable.

[0049] The present invention can be explained through the following operation mode:

[0050] (1) Clamping principle of the inner clamping mechanism

[0051] Power transmission mechanism: After the first motor 28 is started, it drives the first screw rod 22 to rotate. Since the movable sleeve 23 is threadedly connected to the first screw rod 22 and the limiting rod 5 limits its circumferential rotation, the movable sleeve 23 can only move axially along the limiting rod 5.

[0052] The clamping plates open and close synchronously: When the movable sleeve moves, the connecting rod 27 swings through the first hinge seat 24, and the other end of the connecting rod pushes the clamping plates 25 to slide linearly on the support disk 21. Because the clamping plates 25 are arranged in a circular array, when the movable sleeve 23 moves toward the center, all the clamping plates 25 simultaneously converge inward, evenly clamping the cable from the inner wall; when the movable sleeve 23 moves in the opposite direction, the clamping plates 25 release.

[0053] Key function: The limit rod 5 ensures the linear motion of the movable sleeve, avoids uneven force on the clamping plate, and ensures the stability of the inner clamping force.

[0054] (2) Dynamic clamping principle of the outer clamping mechanism

[0055] Pressure transmission of the magnetorheological fluid: The reservoir (composed of the reservoir 33, the connecting groove, and the tensioning elastic body 32) is filled with magnetorheological fluid, whose viscosity varies with the intensity of the magnetic field. When the first electromagnet 36 is energized, it repels the magnetic plate on the piston plate 34 with the same polarity as the first electromagnet 36. This magnetic repulsion overcomes the force of the return spring 35, pushing the piston plate 34 inward from the reservoir 33. This forces the magnetorheological fluid through the connecting groove and into the tensioning elastic body 32.

[0056] Precisely adjustable clamping force: When the magnetorheological fluid is pressurized, the elastic body 32 expands and contracts inward, applying clamping force to the cable's outer wall. Simultaneously, the excitation coil within the elastic body 32 adjusts the magnetic field strength and thus the viscosity of the magnetorheological fluid: a stronger magnetic field increases the viscosity and strengthens the clamping force; a lower magnetic field reduces the clamping force.

[0057] Power-off reset: When the power is off, the reset spring 35 pushes the piston plate 34 to reset, the magnetorheological fluid flows back, the elastic body 32 is tightened to restore its original state, and the cable is released.

[0058] (3) Pre-stretching principle of paving mechanism

[0059] Transverse Stretching and Flattening: A second motor 47 rotates the second screw 46. Because the threads on both sides of the second screw 46 run in opposite directions, the two moving blocks 42 move toward or away from each other along the support platform 41, driving the control rail 43 to move synchronously. The stretching block 44 is fixedly connected to the support disc 21. When the control rail 43 moves, the stretching block 44 pulls on the support discs 21 on both sides, stretching the cable horizontally on the test platform 1 and eliminating any bends or wrinkles.

[0060] Gradual adjustment of stretching strength:

[0061] Initial buffer stage: When no power is applied, the compression spring 7 pushes the stretching block to the initial position in the limit slot 6, allowing the cable to have buffer space in the initial stage of stretching to avoid damage caused by sudden force.

[0062] During the strong stretching phase, when power is applied, the opposite poles of second electromagnet 8 attract each other. This magnetic attraction overcomes the force of compression spring 7, causing stretching block 44 to move further within retaining slot 6, increasing the cable's stretch. Adjusting the operating power of second electromagnet 8 varies the magnetic attraction, enabling precise control of varying stretching forces to meet the tensile testing requirements of cables of varying specifications.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cable tensile strength testing device, characterized in that: include: Test platform (1); An inner clamping mechanism (2), wherein the inner clamping mechanism (2) is provided with two groups and symmetrically distributed above the test platform (1), and is used to clamp and fix the cable from the inner side thereof, the inner clamping mechanism (2) comprising a supporting disc (21), a first screw rod (22) being rotatably connected to the center position of the supporting disc (21), a movable sleeve (23) being threadedly connected to the first screw rod (22), a plurality of first hinge seats (24) distributed in a circumferential array being provided on the movable sleeve (23), a plurality of clamping plates (25) distributed in a circumferential array being linearly slidably connected to the supporting disc (21), each of the clamping plates (25) being provided with a second hinge seat (26), a connecting rod (27) being hinged between the first hinge seat (24) and the second hinge seat (26) at the corresponding position, and a first motor (28) for driving the connecting rod (27) being fixedly connected to the side of the supporting disc (21) away from the first screw rod (22); An outer clamping mechanism (3) is used to clamp and fix the cable from the outside; The flattening mechanism (4) is used to flatten the cable before stretching it, so as to accurately detect the tensile strength of the cable.

2. The cable tensile strength testing device according to claim 1, characterized in that: A limiting rod (5) is fixedly connected to a side wall of the support disc (21) close to the movable sleeve (23), and the movable sleeve (23) moves linearly along the limiting rod (5).

3. The cable tensile strength testing device according to claim 1, characterized in that: The outer clamping mechanism (3) comprises a fixing ring (31) fixedly connected to the side wall of the supporting disc (21); a tightening elastic body (32) is fixedly connected to the inner wall of the fixing ring (31); a liquid storage tank (33) is fixedly connected to the outer wall of the fixing ring (31); a piston plate (34) is sealingly and slidably connected to the interior of the liquid storage tank (33); a return spring (35) is provided between the piston plate (34) and the interior of the liquid storage tank (33); a first electromagnet (36) is fixedly connected to the inner wall of the liquid storage tank (33) away from the return spring (35); a magnetic sheet is provided on the side of the piston plate (34) close to the first electromagnet (36); when the first electromagnet (36) is energized, it repels the same pole as the magnetic sheet, and the magnetic repulsion force is greater than the elastic force of the return spring (35).

4. The cable tensile strength testing device according to claim 3, characterized in that: The fixing ring (31) is provided with a connecting groove connected to a liquid storage tank (33) and a tightening elastic body (32); a liquid storage space is formed between a space on one side of the liquid storage tank (33) close to the tightening elastic body (32), the connecting groove and the interior of the tightening elastic body (32), and the liquid storage space is filled with magnetorheological fluid.

5. The cable tensile strength testing device according to claim 4, characterized in that: An excitation coil for controlling the magnetic field intensity around the magnetorheological fluid is provided in the tightening elastic body (32).

6. The cable tensile strength testing device according to claim 1, characterized in that: The paving mechanism (4) includes a support platform (41) fixedly connected to the upper end of the test platform (1), two symmetrically arranged moving blocks (42) are linearly slidably connected to the support platform (41), the upper end of the moving block (42) is fixedly connected to a control track (43), a stretching block (44) is provided in the control track (43), and the stretching block (44) is fixedly connected to the support disc (21) at the corresponding position, two fixed blocks (45) are fixedly connected to the support platform (41), a second screw rod (46) is rotatably connected between the two fixed blocks (45), and the two sides of the second screw rod (46) are provided with screw threads with opposite spiral directions, and the two sides of the second screw rod (46) are respectively threadedly connected to the two moving blocks (42), and a second motor (47) for driving the second screw rod (46) is fixedly connected to one of the fixed blocks (45).

7. The cable tensile strength testing device according to claim 6, characterized in that: A limiting groove (6) is provided on the control track (43), and the stretching block (44) is slidably connected to the inner wall of the limiting groove (6).

8. The cable tensile strength testing device according to claim 7, characterized in that: A compression spring (7) is provided between the stretching block (44) and the side wall of the corresponding control track (43); a second electromagnet (8) is provided on a side wall of the stretching block (44) and the control track (43) away from the compression spring (7); when the two second electromagnets (8) are energized, opposite poles attract each other, and the magnetic attraction force is greater than the elastic force of the compression spring (7).

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