A tensile testing device for polyethylene silicon core tubes

Abstract

The application discloses a kind of tensile testing devices for polyethylene silicon core pipe.The upper clamp and the lower clamp are arranged on the testing machine body in a lifting manner;one side of the clamp seat is provided with a first motor, the output shaft of the first motor is connected with a first screw rod, the first screw rod is a left-right screw rod, the left-hand thread section and the right-hand thread section of the first screw rod are respectively in transmission connection with the first clamping block and the second clamping block;the first clamping block is provided with a concave jaw, the second clamping block is provided with a convex jaw, and the concave jaw and the convex jaw are respectively attached to the outer surface of the polyethylene layer outside the polyethylene silicon core pipe sample and the outer surface of the silicon core layer inside the polyethylene silicon core pipe sample.The tensile testing device for polyethylene silicon core pipe provided by the application realizes the automatic adjustment of the distance between the upper and lower clamps, the automatic clamping and the automatic tensile testing during the tensile testing process of the polyethylene silicon core pipe sample.

Description

Technical Field

[0001] This invention relates to the field of tensile testing technology, and more particularly to a tensile testing device for polyethylene silicon core tubes. Background Technology

[0002] Polyethylene silicon core pipe is a composite pipe made of high-density polyethylene (HDPE) as the outer substrate and a low-friction silicon core layer formed by co-extrusion of the inner wall. It is widely used in fiber optic communication, power communication, broadcasting networks, and integrated utility tunnels. Due to its combination of the excellent mechanical properties of polyethylene and the low-friction characteristics of the silicon core layer, it can significantly reduce the resistance of optical cable laying, increase cable blowing distance, and improve construction efficiency. Tensile properties are an important indicator for evaluating the mechanical properties of polyethylene silicon core pipe. The test results not only directly reflect the pipe's tensile strength and elongation at break, but also serve as an important basis for assessing the stability of the co-extrusion molding process, the quality of interlayer bonding, and the reliability of the product in service.

[0003] Currently, the tensile properties of polyethylene-silicone core tubes are typically tested using an electronic universal testing machine in conjunction with mechanical clamps. According to testing standards, specimens can be prepared as dumbbell-shaped samples for tensile testing, or, for specific research purposes, uncirculated tube specimens can be used. However, existing testing devices are primarily designed for homogeneous plastic specimens, and their clamping structures often employ flat-mouthed, serrated, or wedge-shaped clamps. The specimen is fixed by applying radial pressure to the clamping surfaces to generate friction. This approach has limitations in its applicability to composite structures with an outer polyethylene layer and an inner silicon core layer.

[0004] The silicon core layer on the inner wall of the polyethylene silicon core tube has a low surface friction coefficient. Traditional clamps mainly rely on external surface friction to hold the specimen. When the clamping force is insufficient, the specimen is prone to axial slippage during tensile testing. If the clamping force is increased to improve clamping stability, it can easily cause local indentation, plastic deformation, or even premature failure of the clamping end in the polyethylene layer, causing the fracture location to deviate from the gauge length region, affecting the authenticity and repeatability of the test results. Especially for dumbbell-shaped specimens, due to the significant difference in cross-sectional dimensions between the clamping end and the gauge length, local stress concentration is more likely to form in the clamping area, placing higher demands on the clamping method.

[0005] In existing tensile testing equipment, the adjustment and clamping of the upper and lower clamps are generally performed manually. Operators must manually adjust the clamp spacing, tighten the clamping blocks, or control independent drive mechanisms to complete the clamping, with the degree of clamping mainly based on experience. Due to the lack of effective synchronous control and status feedback mechanisms, the upper and lower clamps are prone to asynchronous movements, inconsistent clamping amounts, or clamping center offsets during the clamping process. This can lead to eccentric force on the specimen and uneven initial preload, thus affecting the accuracy and consistency of tensile test data.

[0006] Existing testing devices typically lack real-time monitoring capabilities for clamping status, fixture position, and drive mechanism operation. When the fixture is not properly clamped, the drive mechanism is out of sync, or a drive component malfunctions, the equipment often fails to identify the issue promptly and take interlocking protection measures, potentially continuing to execute subsequent tensile procedures, leading to test failure or even equipment damage. This is detrimental to the automated control and operational safety of the testing process.

[0007] During sample installation, existing equipment generally lacks a rapid positioning structure for polyethylene silicon core tube samples. For dumbbell-shaped samples, manual support is required for centering; for samples of different specifications or shapes, it is usually necessary to change the corresponding clamps or repeatedly adjust the clamping position, which not only reduces the testing efficiency but also increases the complexity of operation, making it difficult to meet the needs of batch and standardized testing of polyethylene silicon core tubes.

[0008] Chinese Patent CN118258687A discloses a universal testing machine, relating to the field of testing equipment. It includes a frame, a drive unit, and two clamps. Each clamp includes a gripper, two hydraulic cylinders, a first piston, and a clamping block. The clamping block has suction holes on its sidewalls, and a suction mechanism is installed inside the first piston. The suction mechanism evacuates air from the suction holes, causing the clamping block to adsorb sheet-like materials. The clamping block has receiving grooves on its sidewalls, where columnar materials are located. This application utilizes the receiving grooves and suction holes. When the test material is columnar, the two clamping blocks clamp the columnar material through the two receiving grooves, increasing the contact area between the columnar material and the clamping blocks, resulting in better clamping and fixing. When the test material is sheet-like, the two clamping blocks clamp the sheet material, which blocks the suction holes. The suction mechanism inside the first piston evacuates air from the suction holes, causing the clamping blocks to adsorb the sheet material, thus improving the clamping effect.

[0009] Chinese Patent Publication No. CN119688451A discloses a universal testing machine for engineering materials; comprising: a base; a mounting platform mounted on the base; a lifting mechanism disposed between the mounting platform and the base; a lifting platform mounted on the output end of the lifting mechanism; and a first clamping sleeve mounted on the lifting platform; wherein the first clamping sleeve includes a housing with a circular opening at the bottom of the housing, and a clamping component disposed inside the housing, the clamping component including two moving plates and a driving mechanism for driving the two moving plates to move closer or further apart; a central clamping block is mounted on each moving plate, the two central clamping blocks are disposed opposite each other, and the two central clamping blocks are elastically slidably mounted on the moving plates along the linear direction of movement of the moving plates, and a first clamping block is disposed on both sides of the moving plates; and a second clamping sleeve disposed directly below the first clamping sleeve and having the same structure as it, the second clamping sleeve being fixedly mounted on the base.

[0010] The two inventions described above have the following problems in practice: The adjustment and clamping processes of the upper and lower clamps of the two universal testing machines generally rely on manual operation. The operator must first visually lower the upper clamp to the estimated position and raise the lower clamp to the estimated position, then repeatedly adjust the clamp spacing according to the sample size, and finally complete the sample clamping by tightening the clamping blocks or controlling the independent drive mechanism. The entire clamping process is cumbersome, time-consuming, highly dependent on the operator's experience, has low testing efficiency, and high labor costs. Furthermore, the two universal testing machines lack real-time detection and feedback control of the clamping position and clamping status; the degree of clamping mainly relies on manual judgment, making it difficult to ensure consistency in each clamping. When there are differences in the clamping forces of the upper and lower clamps or when the clamping actions are asynchronous, it can easily lead to uneven force on both ends of the sample, inconsistent initial preload, or sample axis misalignment, causing eccentric force on the sample during tensile testing, thus affecting the accuracy and repeatability of test data such as tensile strength and elongation at break. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above and to provide a tensile testing device for polyethylene silicon core tubes.

[0012] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: A tensile testing device for polyethylene silicon core tubes includes a testing body, an upper clamp, and a lower clamp. Each of the upper and lower clamps includes a first clamping block and a second clamping block, which are slidably mounted on a clamping seat. The clamping seat is mounted on an adjusting seat, which is vertically adjustable on the testing body. A first motor is mounted on one side of the clamping seat, and the output shaft of the first motor is connected to a first lead screw. The first lead screw is a left-hand and right-hand lead screw with left-hand and right-hand threads respectively machined at both ends. The left-hand and right-hand threaded sections of the first lead screw are respectively connected to the first clamping block and the second clamping block for transmission. The clamping block has concave jaws, and the second clamping block has convex jaws. The outer peripheral wall of the convex jaws has several spikes, each of which is embedded in the silicon core layer of the polyethylene silicon core tube sample. The clamping seat has a mounting groove near the end face of the polyethylene silicon core tube sample. One of the spikes extends into the mounting groove and has an integrally formed trigger section at one end near the mounting groove. The trigger section extends into the mounting groove, and a limit switch is provided in the mounting groove. When the concave jaws and convex jaws are respectively clamped against the outer surface of the polyethylene layer on the outside and the outer surface of the silicon core layer on the inside of the polyethylene silicon core tube sample, the trigger section contacts the roller arm of the limit switch.

[0013] In one embodiment, the output shaft of the first motor is detachably connected to the first lead screw; the side ends of the first clamping block and the second clamping block are respectively detachably equipped with a first connecting block and a second connecting block, and the left-hand threaded section and the right-hand threaded section of the first lead screw are respectively threadedly connected to the first connecting block and the second connecting block.

[0014] In one embodiment, the fixture base is provided with a sliding groove, and the first clamping block and the second clamping block are provided with sliders, which are slidably disposed in the sliding groove; the sliding groove is in communication with the mounting groove, and the depth of the mounting groove is greater than the depth of the sliding groove.

[0015] In one embodiment, the convex jaws are arc-shaped convex jaws, and the concave jaws have several anti-slip grooves on the end face that contacts the polyethylene layer of the polyethylene silicon core tube sample.

[0016] In one embodiment, a sliding rod is provided on the first clamping block and the second clamping block along the sliding direction of the two clamping blocks, and a tension spring is provided on the outer sleeve of the sliding rod; when the concave jaws and convex jaws are respectively attached to and clamped on the outer surface of the polyethylene layer on the outside and the outer surface of the silicon core layer on the inside of the polyethylene silicon core tube sample, the tension spring is in a compressed state.

[0017] In one embodiment, a first outer positioning block is fixedly provided on the outer side of the first connecting block of the upper clamp. The first outer positioning block is U-shaped. A first inner positioning block is fixedly provided on the outer side of the first connecting block of the lower clamp. The first inner positioning block is located inside the first outer positioning block. Metal plates are embedded on both sides of the first inner positioning block. A first proximity switch is embedded on both sides of the first outer positioning block. The first proximity switch extends into the interior of the first outer positioning block. The metal plate on the first inner positioning block on the same side is arranged opposite to the sensing end face of the first proximity switch.

[0018] In one embodiment, the polyethylene silicon core tube sample is a dumbbell-shaped sample, which includes clamping ends at both ends and a gauge length section in the middle, with the width of the clamping ends being greater than the width of the gauge length section. A first reinforcing rib is fixedly provided on the end face of the first clamping block of the upper or lower clamp near the gauge length section of the dumbbell-shaped sample, and a slide rail is provided on the first reinforcing rib. A second reinforcing rib is fixedly provided on the end face of the second clamping block of the upper or lower clamp near the gauge length section of the dumbbell-shaped sample, and the second reinforcing rib is slidably disposed within the slide rail of the first reinforcing rib. The first reinforcing rib and the second reinforcing rib are respectively disposed in the area where the clamping ends of the dumbbell-shaped sample are wider than the gauge length section.

[0019] In one embodiment, a connecting rod is fixedly provided on the testing machine body, and a sample positioning sleeve is provided on the connecting rod. A dumbbell-shaped sample is placed inside the sample positioning sleeve. The width of the clamping end of the dumbbell-shaped sample is greater than the outer diameter of the sample positioning sleeve, and the width of the gauge length section of the dumbbell-shaped sample is less than the inner diameter of the sample positioning sleeve.

[0020] In one embodiment, the upper and lower ends of the connecting rod are each provided with a first external fixing rod. The clamping seat at the upper end and the clamping seat at the lower end are respectively fixed with a first internal fixing rod on their sides near the first external fixing rod. A metal plate is embedded inside each of the first internal fixing rods. A second proximity switch is fixed through each of the first external fixing rods. The metal plate on the first internal fixing rod is disposed opposite to the sensing end face of the second proximity switch. The distance between the metal plate on the first internal fixing rod and the sensing end face of the second proximity switch is less than the rated sensing distance of the second proximity switch.

[0021] In one embodiment, a first guide rod and a second guide rod are respectively provided on both sides of the testing body. The first guide rod and the second guide rod are fixedly connected to the output shaft of a second motor, and the second motor is fixedly mounted on the testing body. The rod body of the first guide rod and the second guide rod includes an upper section and a lower section. The upper section of the first guide rod is a threaded section and the lower section is a smooth section. The upper section of the second guide rod is a smooth section and the lower section is a threaded section. One side of the upper adjustment seat is threadedly connected to the threaded section of the first guide rod, and the other side is slidably sleeved on the smooth section of the second guide rod. The other side of the lower adjustment seat is threadedly connected to the threaded section of the second guide rod, and the other side is slidably sleeved on the smooth section of the first guide rod. The test machine is equipped with a controller and a power module. The output terminals of the limit switch, the first proximity switch, and the second proximity switch are electrically connected to the input terminal of the controller, and the output terminal of the controller is electrically connected to the input terminals of the first motor and the second motor, respectively. The power module supplies power to the controller, the limit switch, the first proximity switch, the second proximity switch, the first motor, and the second motor.

[0022] Compared with existing technologies, the beneficial effects of this invention are: (1) In view of the composite structure of the polyethylene layer on the outside and the silicon core layer on the inside of the polyethylene silicon core tube sample, the present invention clamps the sample by using concave jaws and convex jaws, and sets spikes on the convex jaws that can be embedded in the silicon core layer to improve the limiting ability of the low friction silicon core layer; the present invention realizes clamping position detection and automatic shutdown control by using the combination of trigger segment and limit switch.

[0023] (2) The present invention is provided with a clamping synchronization monitoring mechanism consisting of a first outer positioning block, a first inner positioning block, a metal plate and a first proximity switch to realize real-time detection of the operating status of the first motors corresponding to the upper and lower clamps; when the speeds of the two first motors are not synchronized or one of the first motors fails, the controller can issue a stop command in time, thereby ensuring that the upper and lower clamps complete clamping synchronously and at the same speed, avoiding the sample being subjected to uneven load, and improving the accuracy and repeatability of tensile test results.

[0024] (3) The present invention is provided with a clamping position detection mechanism consisting of a first outer fixing rod, a first inner fixing rod, a metal plate and a second proximity switch, so as to realize automatic monitoring and feedback control of whether the upper clamp and the lower clamp have reached the preset clamping position, thereby realizing automatic clamping distance adjustment and precise positioning, reducing manual adjustment error, improving sample clamping efficiency and testing automation.

[0025] (4) The present invention provides a first reinforcing rib and a second reinforcing rib that cooperate with each other on the first clamping block and the second clamping block, which not only improves the overall structural strength and deformation resistance of the clamping block, but also forms an auxiliary limit on the clamping end of the dumbbell-shaped specimen when slippage occurs during the specimen clamping process, preventing the specimen from falling out of the clamp and improving the reliability and safety of the tensile test process. Attached Figure Description

[0026] Figure 1 A perspective view of a tensile testing device for polyethylene silicon core tubes provided in an embodiment of the present invention; Figure 2 for Figure 1 Another structural diagram; Figure 3 A front view of a tensile testing apparatus for polyethylene silicon core tubes provided in an embodiment of the present invention; Figure 4 This is a perspective view of the upper and lower clamps holding a dumbbell-shaped sample according to an embodiment of the present invention. Figure 5 A perspective view of the connecting rod, sample positioning sleeve, and first external fixing rod provided in an embodiment of the present invention; Figure 6 A perspective view of the upper clamp in the clamping state provided in an embodiment of the present invention; Figure 7 for Figure 6 Another structural diagram; Figure 8 A top view of the upper clamp in the clamping state provided in an embodiment of the present invention; Figure 9 A perspective view of the upper clamp in an unclamped state provided in an embodiment of the present invention; Figure 10 This is a top view of the upper clamp in an unclamped state according to an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached drawings: 1. Test body; 2. First clamping block; 3. Second clamping block; 4. Fixture base; 5. Adjustment base; 6. First motor; 7. First lead screw; 8. Concave jaws; 9. Convex jaws; 10. Spike; 101. Trigger section; 11. Mounting slot; 12. Limit switch; 13. First connecting block; 14. Second connecting block; 15. Slide groove; 16. Slider; 17. Anti-slip groove; 18. Slide rod; 19. Tension spring; 20. First external fixing... 21. Positioning block; 22. First inner positioning block; 23. Metal plate; 24. First proximity switch; 25. Dumbbell-shaped specimen; 26. First reinforcing rib; 27. Second reinforcing rib; 28. Connecting rod; 29. ​​Specimen positioning sleeve; 30. First outer fixing rod; 31. First inner fixing rod; 32. Second proximity switch; 33. First guide rod; 34. Second guide rod; 35. Second motor; 36. Silicon core layer; 37. Controller; 38. Power module; 39. Polyethylene layer. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0029] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Example like Figure 1-10As shown, a tensile testing device for polyethylene silicon core tubes includes a testing body 1, an upper clamp, and a lower clamp. Both the upper and lower clamps include a first clamping block 2 and a second clamping block 3, which are slidably mounted on a clamping seat 4. The clamping seat 4 is mounted on an adjusting seat 5, which is vertically adjustable on the testing body 1. A first motor 6 is mounted on one side of the clamping seat 4, and the output shaft of the first motor 6 is detachably connected to a first lead screw 7. The first lead screw 7 is a left-handed lead screw with left-hand and right-handed threads machined at both ends. The left-handed and right-handed threaded sections of the first lead screw 7 are respectively connected to the first clamping block 2 and the second clamping block 3. A first connecting block 13 and a second connecting block 14 are detachably mounted on the side ends of the first clamping block 2 and the second clamping block 3, respectively. The left-handed and right-handed threaded sections of the first lead screw 7 are threadedly connected to the first connecting block 13 and the second connecting block 14, respectively. The first motor 6 drives the first lead screw 7 to rotate, thereby causing the first clamping block 2 and the second clamping block 3 to move synchronously towards or away from each other, realizing the clamping or releasing action.

[0032] The first clamping block 2 has concave jaws 8, and the second clamping block 3 has convex jaws 9, which are arc-shaped. Several anti-slip grooves 17 are formed on the end face of the concave jaw 8 that contacts the polyethylene layer 38 of the polyethylene silicon core tube sample to increase friction and prevent slippage. Several spikes 10 are provided on the outer peripheral wall of the convex jaw 9. Each spike 10 is embedded in the silicon core layer 35 of the polyethylene silicon core tube sample to penetrate the silicon core layer 35 and enhance clamping stability.

[0033] The clamp base 4 has a mounting groove 11 on the end face near the polyethylene silicon core tube sample. One of the spikes 10 extends from the end near the mounting groove 11 and is integrally formed with a trigger section 101. The trigger section 101 extends into the mounting groove 11, and a limit switch 12 is provided in the mounting groove 11. When the concave jaws 8 and convex jaws 9 are respectively attached to the outer surface of the polyethylene layer 38 on the outside and the outer surface of the silicon core layer 35 on the inside of the polyethylene silicon core tube sample, the trigger section 101 contacts the roller arm of the limit switch 12. The limit switch 12 is used to detect whether the clamping is in place and send a signal to control the first motor 6 to stop.

[0034] A sliding groove 15 is provided on the fixture base 4. A slider 16 is provided on the first clamping block 2 and the second clamping block 3, and the slider 16 is slidably disposed in the sliding groove 15. The sliding groove 15 is interconnected with the mounting groove 11, and the depth of the mounting groove 11 is greater than the depth of the sliding groove 15. A sliding rod 18 is provided on the first clamping block 2 and the second clamping block 3 along the sliding direction of the two clamping blocks, and a tension spring 19 is sleeved on the sliding rod 18. When the concave jaws 8 and the convex jaws 9 are respectively attached to and clamped on the outer surface of the polyethylene layer 38 on the outside and the inner surface of the silicon core layer 35 on the inside of the polyethylene silicon core tube sample, the tension spring 19 is in a compressed state, and the tension spring 19 is used to reset the first clamping block 2 and the second clamping block 3.

[0035] A first outer positioning block 20, which is U-shaped, is fixedly mounted on the outer side of the first connecting block 13 of the upper clamp. A first inner positioning block 21, located inside the first outer positioning block 20, is fixedly mounted on the outer side of the first connecting block 13 of the lower clamp. Metal plates 22 are embedded on both sides of the first inner positioning block 21, and first proximity switches 23 are embedded on both sides of the first outer positioning block 20, extending into the interior of the first outer positioning block 20. The metal plates 22 on the first inner positioning block 21 located on the same side are positioned opposite to the sensing end faces of the first proximity switches 23.

[0036] The first proximity switch 23 is used to detect whether the two first motors 6 at the upper and lower ends rotate synchronously and at the same speed. If the rotation speeds of the two first motors 6 at the upper and lower ends are inconsistent, the distance between the metal plate 22 and the first proximity switch 23 will change. When the metal plate 22 moves into the rated sensing distance of the first proximity switch 23, the first proximity switch 23 sends a signal to the controller 36. The controller 36 controls the two first motors 6 to stop working in order to readjust the two first motors 6 to ensure that the two first motors 6 rotate synchronously and at the same speed, and to ensure that the first clamping block 2 and the second clamping block 3 at the upper and lower ends clamp the polyethylene silicon core tube sample at the same time. If one of the first motors 6 at the upper or lower end is damaged and cannot work, the distance between the metal plate 22 and the first proximity switch 23 will also change. The metal plate 22 will also move into the rated sensing distance of the first proximity switch 23. The first proximity switch 23 will send a signal to the controller 36. The controller 36 will control the two first motors 6 to stop working in order to replace the damaged first motor 6, ensuring that the two first motors 6 rotate synchronously and at the same speed, and ensuring that the first clamping block 2 and the second clamping block 3 at the upper and lower ends clamp the polyethylene silicon core tube sample at the same time.

[0037] The polyethylene silicon core tube specimen is a dumbbell-shaped specimen 24, which includes clamping ends at both ends and a gauge length section in the middle. The width of the clamping ends is greater than the width of the gauge length section. A first reinforcing rib 25 is fixedly provided on the end face of the first clamping block 2 of the upper or lower clamp near the gauge length section of the dumbbell-shaped specimen 24, and a sliding track is provided on the first reinforcing rib 25. A second reinforcing rib 26 is fixedly provided on the end face of the second clamping block 3 of the upper or lower clamp near the gauge length section of the dumbbell-shaped specimen 24, and the second reinforcing rib 26 is slidably disposed within the sliding track of the first reinforcing rib 25. The first reinforcing rib 25 and the second reinforcing rib 26 are respectively disposed in the area of ​​the clamping ends of the dumbbell-shaped specimen 24 that is wider than the gauge length section. The first reinforcing rib 25 and the second reinforcing rib 26 are used to strengthen the structural strength of the first clamping block 2 and the second clamping block 3, and at the same time, they can lock the clamping ends of the dumbbell-shaped specimen 24 to prevent the specimen from falling off when slippage occurs.

[0038] A connecting rod 27 is fixedly mounted on the testing body 1. A sample positioning sleeve 28 is mounted on the connecting rod 27, and a dumbbell-shaped sample 24 is placed inside the sample positioning sleeve 28. The width of the clamping end of the dumbbell-shaped sample 24 is greater than the outer diameter of the sample positioning sleeve 28, and the width of the gauge length section of the dumbbell-shaped sample 24 is smaller than the inner diameter of the sample positioning sleeve 28. The sample positioning sleeve 28 is used for pre-positioning the sample to facilitate accurate clamping by the fixture.

[0039] Both the upper and lower ends of the connecting rod 27 are provided with first outer fixing rods 29. First inner fixing rods 30 are fixedly installed on the sides of the upper and lower clamping seats 4 near the first outer fixing rods 29, respectively. A metal plate 22 is embedded inside each first inner fixing rod 30, and a second proximity switch 31 is fixedly installed on each first outer fixing rod 29. The metal plate 22 on the first inner fixing rod 30 is positioned opposite to the sensing end face of the second proximity switch 31, and the distance between the metal plate 22 on the first inner fixing rod 30 and the sensing end face of the second proximity switch 31 is less than the rated sensing distance of the second proximity switch 31. The second proximity switch 31 is used to detect whether the upper and lower clamping seats 4 have reached the set clamping position, thereby automating the lifting and adjusting distance.

[0040] The testing machine body 1 has a first guide rod 32 and a second guide rod 33 on each side. The first guide rod 32 and the second guide rod 33 are fixedly connected to the output shaft of the second motor 34, which is fixedly mounted on the testing machine body 1. The rods of the first guide rod 32 and the second guide rod 33 include an upper section and a lower section. The upper section of the first guide rod 32 is a threaded section, and the lower section is a smooth section. The upper section of the second guide rod 33 is a smooth section, and the lower section is a threaded section. One side of the upper adjusting seat 5 is threadedly connected to the threaded section of the first guide rod 32, and the other side is slidably sleeved on the smooth section of the second guide rod 33. The other side of the lower adjusting seat 5 is threadedly connected to the threaded section of the second guide rod 33, and the other side is slidably sleeved on the smooth section of the first guide rod 32. The second motor 34 is used to drive the upper and lower adjusting seats 5 to move towards or away from each other to achieve tensile testing.

[0041] The testing unit 1 is equipped with a controller 36 and a power module 37. The output terminals of limit switches 12, the first proximity switch 23, and the second proximity switch 31 are electrically connected to the input terminals of the controller 36, and the output terminals of the controller 36 are electrically connected to the input terminals of the first motor 6 and the second motor 34, respectively. The power module 37 supplies power to the controller 36, limit switches 12, the first proximity switch 23, the second proximity switch 31, the first motor 6, and the second motor 34. The controller 36 is used to receive signals from each sensor and control the motor actions to achieve automated control of clamping, lifting, and stretching.

[0042] If the polyethylene silicon core tube sample is a round tube for tensile testing (not cut into dumbbell-shaped samples), the second clamping block 3 can be replaced with the same clamping block structure as the first clamping block 2, that is, two concave jaws 8 are used to clamp it relative to each other.

[0043] The working principle of this invention is as follows: The polyethylene silicon core tube sample is placed inside the sample positioning sleeve 28. The lowering and raising buttons on the testing machine body 1 are pressed, and the controller 36 controls the two second motors 34 to start working. Driven by the second motors 34, the upper adjusting seat 5 drives the upper clamp seat 4 downwards, and the lower adjusting seat 5 drives the lower clamp seat 4 upwards. When the metal plate 22 on the first inner fixing rod 30 descends into the rated sensing distance of the second proximity switch 31, the second proximity switch 31 sends a signal to the controller 36, and the controller 36 controls the second motor 34 driving the upper adjusting seat 5 to stop working. When the metal plate 22 on the first inner fixing rod 30 descends into the rated sensing distance of the second proximity switch 31, the second proximity switch 31 sends a signal to the controller 36, and the controller 36 controls the second motor 34 driving the lower adjusting seat 5 to stop working. At this time, both the upper clamp seat 4 and the lower clamp seat 4 have reached the set clamping position.

[0044] The controller 36 controls the two first motors 6 to start working synchronously. The upper first motor 6 drives the first lead screw 7 to rotate, and the first lead screw 7 drives the first clamping block 2 and the second clamping block 3 to move synchronously toward the dumbbell-shaped sample 24 until the concave jaws 8 and convex jaws 9 at the upper end are respectively attached to the outer surface of the polyethylene layer 38 on the outside and the outer surface of the silicon core layer 35 on the inside of the polyethylene silicon core tube sample. The concave jaws 8 and convex jaws 9 at the lower end are respectively attached to the outer surface of the polyethylene layer 38 on the outside and the outer surface of the silicon core layer 35 on the inside of the polyethylene silicon core tube sample, and each spike 10 is embedded in the silicon core layer 35 of the polyethylene silicon core tube sample. When the upper or lower trigger segment 101 contacts the roller arm of the limit switch 12, the roller arm of the limit switch 12 is moved, and the limit switch 12 sends a signal to the controller 36. The controller 36 controls the two first motors 6 to stop working, thereby achieving a stable fixation of the upper and lower clamping ends of the dumbbell-shaped sample 24.

[0045] After the two clamping ends of the dumbbell-shaped specimen 24 are securely fixed, the controller 36 controls the second motor 34, which drives the upper adjusting seat 5, to restart operation. Driven by the second motor 34, the upper adjusting seat 5 moves the upper clamp seat 4 upward, and the lower adjusting seat 5 moves the lower clamp seat 4 downward, until the dumbbell-shaped specimen 24 is broken. The gauge length of the dumbbell-shaped specimen 24 is provided with two parallel gauge lines. The area between the two gauge lines is the gauge length zone. When the tensile fracture point of the specimen is located within the gauge length zone, the tensile test result is valid.

[0046] This invention automates the vertical spacing adjustment, clamping, and tensile testing of polyethylene silicon core tube samples.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A tensile testing device for polyethylene silicon core tubes, comprising a testing body, an upper clamp, and a lower clamp, wherein the upper clamp and the lower clamp each include a first clamping block and a second clamping block, the first clamping block and the second clamping block being slidably disposed on a clamp seat, the clamp seat being disposed on an adjusting seat, and the testing body being provided with an adjusting seat that can be raised and lowered; characterized in that: A first motor is provided on one side of the clamping base. The output shaft of the first motor is connected to a first lead screw. The first lead screw is a left-handed lead screw with left-handed and right-handed threads machined at both ends respectively. The left-handed and right-handed threaded sections of the first lead screw are respectively connected to the first clamping block and the second clamping block. The first clamping block has concave jaws, and the second clamping block has convex jaws. The outer peripheral wall of the convex jaws has several spikes, each of which is embedded in the silicon core layer of the polyethylene silicon core tube sample. The clamping base has an installation groove on the end face near the polyethylene silicon core tube sample. One of the spikes extends into a trigger section at one end near the installation groove. The trigger section extends into the installation groove, and a limit switch is provided in the installation groove. When the concave jaws and convex jaws are respectively clamped against the outer surface of the polyethylene layer on the outside and the outer surface of the silicon core layer on the inside of the polyethylene silicon core tube sample, the trigger section contacts the roller arm of the limit switch.

2. The tensile testing device for polyethylene silicon core tubes according to claim 1, characterized in that: The output shaft of the first motor is detachably connected to the first lead screw; the first clamping block and the second clamping block are respectively detachably assembled with a first connecting block and a second connecting block at their side ends, and the left-hand threaded section and the right-hand threaded section of the first lead screw are respectively threadedly connected to the first connecting block and the second connecting block.

3. The tensile testing device for polyethylene silicon core tubes according to claim 1, characterized in that: The fixture base is provided with a sliding groove, and the first clamping block and the second clamping block are provided with sliders, which are slidably disposed in the sliding groove; the sliding groove is connected to the mounting groove, and the depth of the mounting groove is greater than the depth of the sliding groove.

4. The tensile testing device for polyethylene silicon core tubes according to claim 1, characterized in that: The convex jaws are arc-shaped convex jaws, and the concave jaws have several anti-slip grooves on the end face that is in contact with the polyethylene layer of the polyethylene silicon core tube sample.

5. The tensile testing device for polyethylene silicon core tubes according to claim 1, characterized in that: The first clamping block and the second clamping block are provided with a sliding rod along the sliding direction of the two clamping blocks, and the sliding rod is fitted with a tension spring; when the concave jaws and convex jaws are respectively attached to the outer surface of the polyethylene layer on the outside and the outer surface of the silicon core layer on the inside of the polyethylene silicon core tube sample, the tension spring is in a compressed state.

6. The tensile testing device for polyethylene silicon core tube according to claim 2, characterized in that: A first outer positioning block is fixedly provided on the outer side of the first connecting block of the upper clamp. The first outer positioning block is U-shaped. A first inner positioning block is fixedly provided on the outer side of the first connecting block of the lower clamp. The first inner positioning block is located inside the first outer positioning block. Metal plates are embedded on both sides of the first inner positioning block. A first proximity switch is embedded on both sides of the first outer positioning block. The first proximity switch extends into the interior of the first outer positioning block. The metal plate on the first inner positioning block on the same side is arranged opposite to the sensing end face of the first proximity switch.

7. A tensile testing device for polyethylene silicon core tubes according to claim 6, characterized in that: The polyethylene silicon core tube sample is a dumbbell-shaped sample, which includes clamping ends at both ends and a gauge length section in the middle. The width of the clamping ends is greater than the width of the gauge length section. A first reinforcing rib is fixedly provided on the end face of the first clamping block of the upper or lower clamp near the gauge length section of the dumbbell-shaped sample. A sliding track is provided on the first reinforcing rib. A second reinforcing rib is fixedly provided on the end face of the second clamping block of the upper or lower clamp near the gauge length section of the dumbbell-shaped sample. The second reinforcing rib is slidably disposed within the sliding track of the first reinforcing rib. The first reinforcing rib and the second reinforcing rib are respectively disposed in the area where the clamping ends of the dumbbell-shaped sample are wider than the gauge length section.

8. A tensile testing device for polyethylene silicon core tubes according to claim 7, characterized in that: A connecting rod is fixedly installed on the testing machine body. A sample positioning sleeve is installed on the connecting rod. A dumbbell-shaped sample is placed inside the sample positioning sleeve. The width of the clamping end of the dumbbell-shaped sample is greater than the outer diameter of the sample positioning sleeve, and the width of the gauge length section of the dumbbell-shaped sample is less than the inner diameter of the sample positioning sleeve.

9. A tensile testing device for polyethylene silicon core tubes according to claim 8, characterized in that: The connecting rod is provided with a first external fixing rod at both the upper and lower ends. The clamping seat at the upper end and the clamping seat at the lower end are respectively fixed with a first internal fixing rod at their sides near the first external fixing rod. A metal plate is embedded inside each of the first internal fixing rods. A second proximity switch is fixed through each of the first external fixing rods. The metal plate on the first internal fixing rod is arranged opposite to the sensing end face of the second proximity switch. The distance between the metal plate on the first internal fixing rod and the sensing end face of the second proximity switch is less than the rated sensing distance of the second proximity switch.

10. A tensile testing device for polyethylene silicon core tubes according to claim 9, characterized in that: The testing machine body is provided with a first guide rod and a second guide rod on both sides. The first guide rod and the second guide rod are fixedly connected to the output shaft of the second motor, which is fixedly mounted on the testing machine body. The rod body of the first guide rod and the second guide rod includes an upper section and a lower section. The upper section of the first guide rod is a threaded section and the lower section is a smooth section. The upper section of the second guide rod is a smooth section and the lower section is a threaded section. One side of the upper adjustment seat is threadedly connected to the threaded section of the first guide rod, and the other side is slidably sleeved on the smooth section of the second guide rod. The other side of the lower adjustment seat is threadedly connected to the threaded section of the second guide rod, and the other side is slidably sleeved on the smooth section of the first guide rod. The test machine is equipped with a controller and a power module. The output terminals of the limit switch, the first proximity switch, and the second proximity switch are electrically connected to the input terminal of the controller, and the output terminal of the controller is electrically connected to the input terminals of the first motor and the second motor, respectively. The power module supplies power to the controller, the limit switch, the first proximity switch, the second proximity switch, the first motor, and the second motor.

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