A device and method for testing the heat distortion of a flame-retardant polyethylene material for cable optical cables

Abstract

The application provides a cable optical cable flame-retardant polyethylene material heat deformation test device and method, which comprises a test device and a water platform, an oven and an automatic clamping device for operating the test device are slidably installed above the water platform; the test device comprises a sample support frame, the sample support frame is slidably connected with two positioning bolts of an existing test device, a group of tension spring supports are arranged above the sample support frame at left and right sides of the existing test device, the tension spring supports comprise upper and lower support plates which are hingedly connected, the upper support plate is located below a clamp plate of the existing test device, and a tension spring is arranged between the two support plates. The device can improve the test quality and efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of flame retardant product quality testing devices and methods, and specifically relates to a heat deformation testing device and method for flame retardant polyethylene materials used in cables and optical fibers. Background Technology

[0002] Industry standard YDT 3832-2021 specifies that the heat distortion test specimen for flame-retardant polyethylene material used in communication cables and optical fibers should be a circular piece with a diameter of 12mm or a square piece with a side length of 12mm and a thickness of (1.25±0.15)mm. The actual thickness must be measured before the test. The specimen, under no stress, is placed in an oven along with the testing equipment. The oven temperature is (90±2)℃, and the temperature is maintained for 1 hour. Afterward, the specimen is placed... Figure 1 The test fixture shown is supported by two equal-height blocks on the horizontal support VII. The horizontal support supports the clamping plate I through two positioning bolts II. A cylindrical pressure bar V is connected to the center of the clamping plate I. The lower end of the cylindrical pressure bar V in the test fixture is placed in the center of the sample. The lower end of the cylindrical pressure bar V is a plane with a diameter of (3.15±0.03) mm. The total pressure of the pressure bar, the cylindrical weight IV and the connecting parts acting perpendicularly on the lower end of the pressure bar is (3.50±0.02) N. After being kept at a constant temperature of (90±2)℃ for 1 hour, the entire test fixture is taken out of the oven. After cooling at room temperature for 1 hour, the sample is taken out and the thickness of the deformed part of the sample is measured and compared with the thickness of the sample before thermal deformation to see if its thermal deformation rate is within 30%.

[0003] The existing technology has the following problems when conducting the above-mentioned experiments: After the sample and fixture are heated for 1 hour, the inspector places the sample on a horizontal plate and then places the lower end of the pressure bar in the center of the sample. During this process, due to the oven temperature of 90℃ and the limited height inside the oven, the inspector can only place the pressure bar by visual inspection at an angle, making it difficult to place the flat surface with a diameter of (3.15±0.03) mm at the lower end of the pressure bar in the center of the sample.

[0004] The total mass of the pressure bar, cylindrical weight, and connecting parts is (3.50±0.02) N. The lower end of the pressure bar is flat. Since human hands often tremble, it is difficult to slowly and steadily press the lower end of the pressure bar onto the center of the sample under this environment. Since the sample has been baked at 90℃ for 1 hour, if the total mass (3.50±0.02) N cannot be slowly and steadily pressed onto the sample, the flat surface of the lower end of the pressure bar will impact the sample and cause the end face to swing and press, thus leading to inaccurate test results.

[0005] After being subjected to 90℃ for 1 hour, the entire test apparatus was removed from the oven. Due to the manual operation, the hammer wobbled during the removal, causing the lower end of the pressure bar to swing and hold the sample. Since the sample had undergone total mass holding and baking at 90℃ for 1 hour, the swing of the lower end of the pressure bar caused the most serious damage to the sample.

[0006] Manual operation is time-consuming and has low testing quality and efficiency. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a heat deformation testing device and method for flame-retardant polyethylene materials used in cables and optical fibers, thereby improving testing quality and efficiency.

[0008] A heat deformation testing device for flame-retardant polyethylene material used in cables and optical fibers includes a testing fixture and a horizontal platform. An oven and an automatic clamping device for operating the testing fixture are slidably installed above the horizontal platform. The test apparatus includes a sample support frame, which is slidably connected to two positioning bolts of the existing test device. A set of tension spring brackets is set on the left and right sides of the existing test device above the sample support frame. The tension spring brackets include an upper support plate and a lower support plate that are hinged to each other. The upper support plate is located below the clamping plate of the existing test device, and a tension spring is set between the two support plates.

[0009] Preferably, the sample support frame includes a sample support plate, and support rods are symmetrically arranged on the left and right sides below the sample support plate.

[0010] Preferably, the sample support plate is provided with a through hole, and the positioning bolt is slidably connected to the through hole.

[0011] Preferably, a positioning groove is provided on the outside of each through hole at the bottom of the sample support plate.

[0012] Preferably, the bottom of the support rod is connected to a foot.

[0013] Preferably, the lower support plate has an L-shaped structure, and the upper support plate has an inverted L-shaped structure.

[0014] Preferably, the automatic clamping device includes an electric cylinder, the output end of which is connected to a horizontal rod, a camera is mounted on the horizontal rod, and a U-shaped plate is connected to the end of the horizontal rod.

[0015] Preferably, the oven is slidably connected to the horizontal platform via a first slide rail slider mechanism, and the electric cylinder is slidably connected to the horizontal platform via a second slide rail slider mechanism.

[0016] Preferably, each set of slide rail slider mechanisms is driven by a corresponding servo motor, and the oven, electric cylinder, camera and servo motor are all communicatively connected to a PLC controller.

[0017] This invention also discloses a method for conducting heat distortion tests on flame-retardant polyethylene materials for cables and optical fibers using the above-mentioned apparatus, specifically including the following steps: Step 1: Hang the test fixture on the U-shaped plate, place the tension spring bracket between the sample support plate and the clamping plate of the existing test device, place the sample in the center of the sample support plate, and ensure that there is a gap distance A between the upper surface of the sample and the lower surface of the cylindrical pressure bar, while the lower end face of the cylindrical pressure bar is located in the center above the sample. Step 2: The PLC controller controls the oven controller to keep the temperature inside the oven at (90±2)℃. Step 3: The PLC controller controls the servo motor and electric cylinder to work, and the U-shaped plate is inserted into the positioning slot below the horizontal plate to move the test fixture into the oven. Step 4: The PLC controller stabilizes the temperature inside the oven at (90±2)℃ and starts timing for 1 hour; Step 5: The PLC controller controls the servo motor and electric cylinder to move. The U-shaped plate is inserted below the upper support plate and lifts the upper support plate. The lower support plate rotates around the hinge under the action of the tension spring. When the image transmitted by the monitoring camera to the PLC controller confirms that the lower support plate is separated from the horizontal plate, the U-shaped plate drives the tension spring bracket to move out of the oven. The cylindrical pressure bar, the weight and the connecting bolt in the original experimental device move down and the cylindrical pressure bar presses on the sample. Step 6: When the temperature inside the oven stabilizes at (90±2)℃, the controller starts timing for 1 hour. The automatic clamping device removes the test fixture from the oven. After the PLC controller starts timing for 1 hour, it issues a prompt sound. The tester removes the heat-deformed sample and measures the thickness of the deformed part to compare with the thickness of the sample before heat deformation, verifying whether its heat deformation rate is within 30%.

[0018] Beneficial effects This invention, without altering the original testing principle and equipment, replaces the water plate for placing the sample with a double-hole horizontal plate, without affecting the sample's pressure and load-bearing capacity. It also adds positioning slots, support rods and feet, tension spring brackets, and automatic sample holding, testing equipment, and oven movement parts to replace manual operation. The operation and control are automatically completed through programming with a camera and display PLC controller. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a structural diagram of an existing experimental device in the background art; Figure 2 This is a diagram showing the usage status of the double-hole horizontal support in the testing equipment; Figure 3 yes Figure 1 Top view; Figure 4 yes Figure 1 Side view; Figure 5 yes Figure 2 AA section view; Figure 6 This is a diagram showing the usage status of the spring bracket support; Figure 7 yes Figure 6 Side view; Figure 8 This is a diagram showing the state of the spring bracket for the horizontal bar moving upwards; Figure 9 This is a schematic diagram showing the state in which the lower end face of the pressure bar holds the sample as the horizontal bar moves downward. Figure 10 The diagram shows how the horizontal bar moving downwards creates a gap between the upper right angle and the upper connecting plate. Figure 11 This is a diagram showing the placement of the test apparatus on the moving device using a spring support. Figure 12 This is a diagram showing the mobile device placing the test fixture into the oven. Figure 13 This is a diagram showing the mobile device returning to its original startup state. Figure 14 yes Figure 13 Top view; Figure 15 This is a diagram showing the state of the mobile device removing the spring bracket; Figure 16 yes Figure 15 Enlarged view of C; Figure 17 This is a diagram showing the status of the mobile device removing the test equipment; Figure 18 yes Figure 17 BB cross-sectional view; Figure 19 It is a control principle diagram; In the diagram: Ⅰ, clamping plate; Ⅱ, positioning bolt; Ⅲ, supporting bolt; Ⅳ, counterweight; Ⅴ, cylindrical pressure bar; Ⅵ, sample; Ⅶ, horizontal support.

[0021] 1. Horizontal platform, 2. Legs, 3. Support rod, 4. Cylindrical counterweight, 5. Suspended counterweight bolt, 6. Lower connecting plate, 7. Connecting bolt, 8. Double-hole horizontal plate, 9. Heat deformation sample, 10. Upper connecting plate, 11. Cylindrical pressure bar, 12. Hole, 13. Gap distance A, 14. Upper right-angle plate, 15. Tension spring, 16. Hinge, 17. Lower right-angle plate, 18. Arc, 19. Horizontal insert rod, 20. Gap distance B, 21. Gap distance C, 22. Slide rail base A, 23. Servo motor A, 24. Slide rail base A, 25. Horizontal plate base A, 26. Horizontal plate base A, 27. Horizontal plate base A, 28. Horizontal plate base A, 29. Horizontal plate base A, 20. Gap distance B, 21. Gap distance C, 22. Slide rail base A, 23. Servo motor A, 24. Horizontal plate base A, 25. Horizontal plate base A, 26. Horizontal plate base A, 27. Horizontal plate base A, 28. Horizontal plate base A, 29. Horizontal plate base A, 20. Horizontal plate base A, 20. Horizontal plate base A, 21. Horizontal plate base A, 22. Horizontal plate base A, 23. Horizontal plate base A, 24. Horizontal plate base A, 25. Horizontal plate base A, 26. Horizontal plate base A, 27. Horizontal plate base A, 28. Horizontal plate base A, 29. Horizontal plate base A, 20. Horizontal plate base A, 20. Horizontal plate base A, 20. Horizontal Plate A, 25 Oven, 26 Door, 27 Horizontal U-shaped plate, 28 Surveillance camera, 29 Horizontal bar, 30 Reinforcing rib plate, 31 Column, 32 Flange, 33 Telescopic end, 34 Electric cylinder, 35 Servo motor C, 36 Slide plate B, 37 Slide rail seat B, 38 Servo motor B, 39 Display PLC controller, 40 Lead screw shaft A, 41 Lead screw shaft B, 42 Door handle, 43 Oven controller, 44 Nut A, 45 Positioning groove, 46 Door switch, 47 Clearance distance D. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0023] refer to Figures 2 to 18 The specific improvements made to the original experimental setup are as follows: the original horizontal plate for placing the sample is replaced with a double-hole horizontal plate 8. Specifically, two mirror-symmetrical vertical holes 12 are provided on either side of the center along the length of the original horizontal plate. Connecting bolts 7 can be inserted vertically into the vertical holes 12 with gaps. The tops of the two connecting bolts 7 are secured to an upper connecting plate 10 with nuts. A cylindrical pressure bar 11 is secured to the center of the upper connecting plate 10 with nuts. The lower ends of the two connecting bolts 7 are secured to a lower connecting plate 6 with nuts. A suspended weight bolt 5 is secured to the lower end of the lower connecting plate 6 with nuts. A cylindrical weight 4 is secured to the lower end of the suspended weight bolt 5 with nuts. The purpose of adding the vertical holes 12 is to reduce the sway of the cylindrical weight 4. Mirror-symmetrical positioning grooves 45 are provided on both sides of the lower surface of the double-hole horizontal plate 8. Support rods 3 are added to the lower surfaces of both ends of the double-hole horizontal plate 8, with feet 2 at the lower ends of the support rods 3. The structure of the experimental setup after adding the double holes 12, positioning grooves 45, support rods 3, and feet 2 is shown in the appendix. Figures 1-4 .

[0024] A tension spring bracket is added. The tension spring bracket consists of an upper right-angle plate 14, a lower right-angle plate 17, a hinge 16, and a tension spring 15. The hinge 16 connects the two right-angled sides of the upper right-angle plate 14 and the lower right-angle plate 17. The tension spring 15 connects the other right-angled side of the upper right-angle plate 14 and the lower right-angle plate 17. The initial tension of the tension spring 15 is half the mass of the lower right-angle plate 17, so the tension value is not large. An arc 18 is provided at the outer right angle of the lower right-angle plate 17. The arc 18 allows the lower end of the lower right-angle plate 17 to slowly and smoothly disengage from the upper surface of the double-hole horizontal plate 8. The tension spring bracket is placed between the double-hole horizontal plate 8 and the upper connecting plate 10 (see attached diagram). Figure 5 and attached Figure 6 .

[0025] The operation and testing equipment, including the moving parts of the oven and the cylindrical pressure bar 11 for pressing the heat deformation specimen 9, are added to replace manual placement. Two electric horizontal moving platforms are placed on the horizontal platform surface 1 of the workbench, with their axes aligned in a straight line. The moving platform on the left, where the oven 25 is mounted, is wider than the moving platform on the right, where the electric cylinder 34 is mounted, but the transmission principle of both electric horizontal moving platforms is the same. The left slide rail A22 is bolted to the horizontal platform surface 1 of the workbench. The servo motor A23 is bolted to the left end face of the slide rail A22. The shaft of the servo motor A23 is a lead screw shaft A40, with a nut A44 screwed onto it. The nut A44 is bolted to the lower surface of the slide plate A24. The other end of the lead screw shaft A40 is inserted into the right end face of the slide rail A22. (See attached diagram). Figure 16 and attached Figure 17 The slide rail seat B37 on the right is fixed to the horizontal platform surface 1 of the worktable by bolts. The servo motor B38 is fixed to the right end face of the slide rail seat B37 by bolts. The shaft of the servo motor B37 is a lead screw shaft B41. A lead screw nut is screwed on the lead screw shaft B41. The lead screw nut is fixed to the lower surface of the slide plate B36 by bolts. The other end of the lead screw shaft B41 is inserted into the left end face of the slide rail seat B37. An electric cylinder 34 is vertically fixed to the upper surface of the slide plate B36 by bolts. A servo motor C35 provides power to the electric cylinder 34. A flange 32 is mounted on the top of the telescopic end 33 of the electric cylinder 34. A cylinder 31 is welded to the top of the flange 32. A horizontal rod 29 is welded to the side of the cylinder 31. A reinforcing rib plate 30 is welded to the upper surface of the horizontal rod 29 and the outer surface of the cylinder 31. The horizontal axis centerline of the horizontal rod 29 is in the same vertical plane as the vertical axis centerline of the electric cylinder 34 and the axis centerline of the servo motor B38. A monitoring camera 28 is fixed to the upper surface of the horizontal rod 29 by bolts. A horizontal U-shaped plate 27 is welded to the end of the horizontal rod 29. Two horizontal insert rods 19 are provided at the front end of the horizontal U-shaped plate 27. The distance between the two horizontal insert rods 19 is the same as the distance between the two positioning grooves 45 on the lower surface of the double-hole horizontal plate 8, and the end face dimension of the horizontal insert rods 19 is smaller than the groove width of the positioning grooves 45. (See attached figure) Figure 5 .

[0026] A display PLC controller 39 is installed on the horizontal surface 1 of the workbench. The electrical control wires of the monitoring camera 28, servo motors A23, B28, C35, oven controller 43, and door switch 46 are all connected to the display PLC controller 39. The test control program and image analysis software are input into the PLC controller 39.

[0027] How to use: Hang the test fixture on the two horizontal insert rods 19, that is, insert the two positioning slots 45 on the lower surface of the double-hole horizontal plate 8 into the two horizontal insert rods 19. Place the tension spring bracket between the double-hole horizontal plate 8 and the upper connecting plate 10 (see attached). Figure 5 and attached Figure 6 The adjusted heat deformation specimen 9 is placed at the center of the double-hole horizontal plate 8. The center of the double-hole horizontal plate 8 is marked with multiple concentric circles of different diameters and rectangular frames of different side lengths. These lines ensure that the heat deformation specimen 9 is placed in the center. There is a gap distance A13 between the upper surface of the heat deformation specimen 9 and the lower surface of the cylindrical pressure bar 11. Simultaneously, the lower end face of the cylindrical pressure bar 11 is located at the center above the heat deformation specimen 9. (See attached diagram) Figure 5 and attached Figure 11 .

[0028] Pressing the test start button in the PLC controller 39 activates all electrical control components. The PLC controller 39 controls the oven controller 43 to maintain the temperature inside the oven 25 at (90±2)℃. The PLC controller 39 controls the door switch 46 to open the door 26. The PLC controller 39 determines whether the location of the test equipment meets the programming requirements based on the image data provided by the monitoring camera 28. If requirements such as the oven 25 being free of debris, capable of accommodating test equipment, and having a flat bottom surface are met, the PLC controller 39 controls the extension / retraction end 33 of the servo motor C35 to extend or retract to ensure the test equipment can enter the oven 25 through the doorway. The PLC controller 39 then starts the servo motor B38. According to the programming, the servo motor B38 starts with a very small rotation angle and slowly increases speed to a constant speed. The lead screw 41 drives the slide plate B36 through the lead screw nut, and all components on it move horizontally and linearly in sync. When the test equipment enters the oven 25, the servo motor B38 slowly decelerates according to the programming until the test equipment can be placed in a suitable position, at which point the servo motor B38 stops working. (See Appendix) Figure 12 The PLC controller 39 controls the servo motor C35 to cause the telescopic end 33 of the electric cylinder 34 to descend at an extremely slow speed. The test fixture mounted on the two horizontal rods 19 also moves down slowly in sync. When the support legs 2 in the test fixture slowly contact the bottom surface of the oven 25, a gap distance D47 is generated between the upper surface of the two horizontal rods 19 and the lower surface of the double-hole horizontal plate 8 (see Appendix). Figure 7The PLC controller 39 can calculate the gap distance D47 based on the rotation angle of the servo motor C35, or it can detect the gap distance D47 based on the image from the monitoring camera 28. When the gap distance D47 is detected, the PLC controller 39 controls the servo motor C35 to stop working and controls the servo motor B38 to rotate rapidly in the opposite direction, causing the slide plate B36 to return to its original starting position. (See attached image) Figure 13 The PLC controller 39 controls the door switch 46 to close the door 26. When the temperature inside the oven 25, transmitted from the oven controller 43 to the PLC controller 39, stabilizes at (90±2)℃, the PLC controller 39 starts timing. After 1 hour, the PLC controller 39 controls the door switch 46 to open the door 26. The PLC controller 39 controls the servo motor B38 to rotate rapidly, causing the fixed parts on the slide plate B36 to move quickly closer to the oven 25. When the two horizontal insertion rods 19 are about to approach the test fixture, the PLC controller 39 controls the servo motor B38 to decelerate. The PLC controller 39 controls the servo motor C35 to raise the telescopic end 33 a certain distance so that the two horizontal insertion rods 19 can be inserted below the upper right-angle plate 14. After rod 19 is inserted below right-angle plate 14, PLC controller 39 controls servo motor B38 to stop working, and PLC controller 39 controls servo motor C35 to work at an extremely slow speed to slowly raise telescopic end 33. The two horizontal rods 19 slowly raise the upper right-angle plate 14, and the lower right-angle plate 17 rotates around the hinge 16 under the action of tension spring 15. The lower right-angle plate 17 has an arc 18 at the outer right angle, and the tension of tension spring 15 is only 1 / 2 of the mass of the lower right-angle plate 17, so the slow rotation of the lower right-angle plate 17 will not cause vibration to the double-hole horizontal plate 8. At this time, there is a gap distance B20 between the upper surface of the heat deformation sample 9 and the lower surface of the cylindrical pressure bar 11. The gap distance B20 is greater than the gap distance A13. (See Appendix) Figure 7 and attached Figure 8 .

[0029] When the image transmitted from the monitoring camera 28 to the PLC controller 39 confirms that the right-angle plate 17 has completed its rotation under the action of the tension spring 15, the PLC controller 39 then controls the servo motor C35 to work in the reverse direction at an extremely slow speed, causing the telescopic end 33 to slowly move downwards. At the same time, the two horizontal insert rods 19 drive the upper connecting plate 10, the cylindrical pressure bar 11 connected to the upper connecting plate 10, the cylindrical hammer 4, and the connecting bolts to move downwards simultaneously and slowly. Finally, the lower end of the cylindrical pressure bar 11 slowly presses against the center of the heat deformation sample 9. (See attached image) Figure 9 When a gap C21 appears between the upper surface of the right-angle plate 14 and the lower surface of the double-hole horizontal plate 8 (see attached diagram),... Figure 10 At this time, PLC controller 39 controls servo motor C35 to stop working and controls servo motor B38 to work in reverse from slow to fast, so that slide plate B36 and all components on slide plate B36, including the "tension spring brackets" hanging on the two horizontal plug rods 19, return to the original starting position. See Appendix. Figure 15 At this time, the PLC controller 39 issued a prompt sound, and the testing personnel removed the "tension spring bracket" from the horizontal plug rod 19.

[0030] When the temperature inside the oven 25, transmitted from the oven controller 43 to the PLC controller 39, stabilizes at (90±2)℃, the PLC controller 39 starts timing. After 1 hour, the PLC controller 39 controls the door switch 46 to open the door 26. The PLC controller 39 then controls the servo motor B38 to rotate rapidly, causing the slide plate B36 and its fixed components to move quickly closer to the oven 25. When the two horizontal rods 19 are about to approach the test fixture, the PLC controller 39 controls the servo motor B38 to decelerate. The PLC controller 39 also controls the servo motor C35 to move its telescopic end 33 downward a certain distance, allowing the two horizontal rods 19 to be inserted into the positioning slot 45 (see attached diagram). Figure 1 After the two horizontal insertion rods 19 are inserted into the positioning slots 45, the PLC controller 39 controls the servo motor B38 to stop working. The PLC controller 39 then controls the servo motor C35 to work at an extremely slow speed, causing the telescopic end 33 to slowly rise until the lower end of the support leg 2 is higher than the lower edge of the oven door 25, at which point the servo motor C35 stops working. The PLC controller 39 then controls the servo motor A23 to rotate the lead screw shaft A40, and the lead screw nut A44 pushes the slide plate A24 to move horizontally to the left. The oven 25, which is fixed on the slide plate A24, also moves to the left synchronously (see attached diagram). Figure 16 When the oven 25 no longer contains the test fixture, the PLC controller 39 starts timing. After 1 hour, the PLC controller 39 issues a prompt sound. The tester removes the heat-deformed sample 9 and measures the thickness of the deformed part to compare with the thickness of the sample before heat deformation, to see if the heat deformation rate is within 30%.

[0031] This experimental apparatus and method, by adding holes 12 to the double-hole horizontal plate 8 to prevent the cylindrical weight 4 from swinging excessively, and by adding positioning grooves, support rods and feet, and tension spring brackets and moving parts, achieves the replacement of manual operation in holding the heat-deformed specimen 9. The tension spring bracket cleverly completes the support function and the action of removing and taking out the tension spring bracket. In particular, after the heat-deformed specimen 9 is held under the pressure of the cylindrical pressure bar 11, the cylindrical weight 4 and the connecting parts with a total mass of (3.50±0.02) N and baked at 90℃ for 1 hour, it only moved a short vertical distance without horizontal movement, while the oven 25 moved horizontally. This plays a key role in ensuring the quality of the test. By eliminating manual operation and preventing damage to the heat-deformed specimen 9, the quality and efficiency of the test are improved.

[0032] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A heat distortion testing device for flame-retardant polyethylene material used in cables and optical fibers, characterized in that, It includes a test fixture and a horizontal platform, with an oven and an automatic clamping device for operating the test fixture slidably mounted on the horizontal platform. The test apparatus includes a sample support frame, which is slidably connected to two positioning bolts of the existing test device. A set of tension spring brackets is set on the left and right sides of the existing test device above the sample support frame. The tension spring brackets include an upper support plate and a lower support plate that are hinged to each other. The lower support plate has an L-shaped structure, and the upper support plate has an inverted L-shaped structure. The upper support plate is located below the clamping plate of the existing test device, and a tension spring is provided between the two support plates; The sample support frame includes a sample support plate, and support rods are symmetrically arranged on the left and right sides below the sample support plate. The sample support plate is provided with through holes, and the positioning bolts are slidably connected to the through holes; a positioning groove is provided on the outside of each through hole on the lower part of the sample support plate. The automatic clamping device includes an electric cylinder, the output end of which is connected to a horizontal rod, a camera is mounted on the horizontal rod, a U-shaped plate is connected to the end of the horizontal rod, and two horizontal insert rods are provided at the front end of the horizontal U-shaped plate. In the initial state, the horizontal insert rod is inserted into the positioning slot, and the tension spring bracket lifts the weight shaft and cylindrical pressure bar upward in the assembled state, leaving a gap between the cylindrical pressure bar and the sample below; the automatic clamping device drives the entire test fixture into the oven. After the oven is heated to the set test temperature and stabilized, the horizontal insert rod raises the upper support plate, causing the lower support plate to rotate hingedly. The weight shaft and cylindrical pressure bar lose support and fall to press the sample. Then the entire tension spring bracket is moved out of the oven.

2. The heat distortion testing device for flame-retardant polyethylene material for cables and optical fibers according to claim 1, characterized in that, The bottom of the support rod is connected to a support foot.

3. The heat distortion testing device for flame-retardant polyethylene material for cables and optical fibers according to claim 1, characterized in that, The oven is slidably connected to the horizontal platform via a first slide rail slider mechanism, and the electric cylinder is slidably connected to the horizontal platform via a second slide rail slider mechanism.

4. The heat distortion testing device for flame-retardant polyethylene material for cables and optical fibers according to claim 3, characterized in that, Each set of slide rail slider mechanisms is driven by a corresponding servo motor, and the oven, electric cylinder, camera and servo motor are all communicatively connected to a PLC controller.

5. A test method for conducting heat distortion tests on flame-retardant polyethylene materials for cables and optical fibers using the apparatus described in claim 4, specifically comprising the following steps: Step 1: Hang the test fixture on the U-shaped plate, place the tension spring bracket between the sample support plate and the clamping plate of the existing test device, place the sample in the center of the sample support plate, and ensure that there is a gap distance A between the upper surface of the sample and the lower surface of the cylindrical pressure bar, while the lower end face of the cylindrical pressure bar is located in the center above the sample. Step 2: The PLC controller controls the oven controller to keep the temperature inside the oven at (90±2)℃. Step 3: The PLC controller controls the servo motor and electric cylinder to work, and the U-shaped plate is inserted into the positioning slot below the horizontal plate to move the test fixture into the oven. Step 4: The PLC controller stabilizes the temperature inside the oven at (90±2)℃ and starts timing for 1 hour; Step 5: The PLC controller controls the servo motor and electric cylinder to move. The U-shaped plate is inserted below the upper support plate and lifts the upper support plate. The lower support plate rotates around the hinge under the action of the tension spring. When the image transmitted by the monitoring camera to the PLC controller confirms that the lower support plate is separated from the horizontal plate, the U-shaped plate drives the tension spring bracket to move out of the oven. The cylindrical pressure bar, the weight and the connecting bolt in the original experimental device move down and the cylindrical pressure bar presses on the sample. Step 6: When the temperature inside the oven stabilizes at (90±2)℃, the controller starts timing for 1 hour. The automatic clamping device removes the test fixture from the oven. After the PLC controller starts timing for 1 hour, it issues a prompt sound. The tester removes the heat-deformed sample and measures the thickness of the deformed part to compare with the thickness of the sample before heat deformation, verifying whether its heat deformation rate is within 30%.

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