Polyurethane material heat resistance detection device and method

Abstract

The application belongs to the technical field of polymer material heat resistance detection equipment, and particularly relates to a polyurethane material heat resistance detection device and method, wherein the polyurethane material heat resistance detection device comprises a hot air box, a heat insulation door is arranged on the hot air box, an expansion bin is fixedly connected to one side of the hot air box, a base is arranged in the hot air box, a supporting assembly is arranged above the base, a lever is arranged above the supporting assembly, a pressure head is fixedly connected to the lower part of the lever, a leveling mechanism is arranged at one end of the lever, a loading assembly is arranged at the other end of the lever, a lifting mechanism is arranged below the loading assembly, and a leveling module for leveling a polyurethane sample is arranged below the base. The above technical scheme can make the hanging basket descend at a very low constant speed, stably transfer the weight of the weight to the load end of the lever, effectively prevent the polyurethane sample from instantaneously collapsing due to sudden stress, and ensure that the measured softening temperature truly reflects the heat resistance of the material.

Description

Technical Field

[0001] This invention belongs to the technical field of heat resistance testing equipment for polymer materials, and particularly relates to a heat resistance testing device and method for polyurethane materials. Background Technology

[0002] Polyurethane, short for polyurethane, is a new type of organic polymer material that is widely used in many sectors of the national economy due to its excellent performance. The heat distortion temperature of polyurethane is an important indicator of its heat resistance. The test principle usually involves placing a sample of specified size on a simply supported beam three-point bending support, heating it at a uniform rate under a constant standard bending stress, and measuring the temperature at which the bending deformation at the center of the sample reaches the specified value. The standard stress is usually applied by lever loading, that is, by suspending a standard weight, which is amplified by the lever and then applied to the upper surface of the sample by the indenter.

[0003] However, polyurethane materials soften easily during heating, and their modulus drops sharply. They are extremely sensitive to minor disturbances and impacts during loading. Existing weight loading mechanisms often use manual direct mounting or a simple lifting platform for quick release in actual use. Such methods cannot avoid the impact load at the moment the weight contacts the lever. For polyurethane samples that have reached the softening temperature, even a small dynamic impact can cause the sample to deform excessively or even crush instantly, resulting in a severely low measured softening temperature and extremely poor data repeatability. Summary of the Invention

[0004] This invention discloses a heat resistance testing device and method for polyurethane materials, aiming to solve the technical problem that existing heat resistance testing devices for polyurethane materials lack measures to achieve stable weight loading without impact.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A heat resistance testing device for polyurethane materials includes a hot air box with an insulation door. An expansion chamber is fixedly connected to one side of the hot air box. A base is installed inside the hot air box. A support assembly for placing a polyurethane sample is installed above the base. A lever is installed above the support assembly and is rotatably connected to the hot air box. A pressure head is fixedly connected to the lower part of the lever via a connecting rod. The end of the lever near the expansion chamber extends into the expansion chamber and is equipped with a leveling mechanism for leveling the lever. A loading assembly is installed at the end of the lever away from the expansion chamber. A lifting mechanism is installed below the loading assembly. A leveling module for leveling the polyurethane sample is installed below the base.

[0006] The following are further optimizations of the above technical solution by the present invention: The leveling mechanism includes a sliding block, which is fixedly connected to the bottom of the lever. A counterweight is slidably connected inside the sliding block. A winding roller is rotatably connected above the lever. A pulling rope is wound on the winding roller. One end of the pulling rope is fixedly connected to the winding roller, and the other end of the pulling rope passes around the guide roller installed on the lever and is fixedly connected to the counterweight.

[0007] Further optimization: A first spring is fixedly connected to the end of the counterweight away from the pulling rope, and the other end of the first spring is fixedly connected to the sliding block. A drive motor is fixedly installed on the lever, and the output end of the drive motor is connected to the winding roller drive.

[0008] Further optimization: The loading component includes a hook, the upper end of which is rotatably connected to the lever, the lower end of which is fixedly connected to a fitting block, a hanging basket is set below the hook, a cantilever rod is fixedly connected above the hanging basket, a centering groove is set at the middle position of the cantilever rod, the centering groove is set correspondingly to the fitting block, a center rod is fixedly connected at the center position of the hanging basket, and a weight is sleeved on the center rod.

[0009] Further optimization: The lifting mechanism includes a lifting fork, an isolation cover is fixedly attached to the inner wall of the hot air box, the lifting fork is slidably connected to the isolation cover via two guide rails, a sleeve is fixedly attached to the lower end of the lifting fork, a lead screw is fitted inside the sleeve, the lead screw is rotatably connected to the hot air box via a connecting block, a nut is threaded onto the lead screw, the nut is fixedly connected to the sleeve, a stepper motor is fixedly installed inside the isolation cover, and the output end of the stepper motor is connected to the lead screw drive.

[0010] Further optimization: Silicone pads are attached to all four claws of the lifting fork.

[0011] Further optimization: The leveling module includes a ball seat and a ball head rod. The ball seat is fixedly connected to the base, and the ball head rod is fixedly connected to the hot air box. The ball head of the ball head rod is located in the hemispherical mounting groove of the ball seat. A fixed plate is fixedly connected inside the hot air box. Multiple leveling components are set on the fixed plate. The multiple leveling components are arranged in a ring around the axis of the ball head rod.

[0012] Further optimization: The leveling component includes a receiving cylinder, which is fixedly connected to a fixed plate. A knob is rotatably connected to the upper end of the receiving cylinder via a bearing. A threaded rod is connected to the inner thread of the knob. A contact head is fixedly connected to the upper end of the threaded rod and is in close contact with the bottom surface of the base. A connecting ring is slidably sleeved on the receiving cylinder. An external toothed ring is fixedly connected to the upper end of the connecting ring. An internal toothed ring is fixedly connected to the lower end of the knob. The external toothed ring and the internal toothed ring are correspondingly arranged. A second spring is sleeved on the receiving cylinder. The two ends of the second spring are fixedly connected to the fixed plate and the connecting ring, respectively.

[0013] Further optimization: A heat insulation ring is fixed to the top of the fixed plate via a receiving frame. A rotating frame is rotatably connected to the outside of the heat insulation ring. Multiple operating ports are opened on the rotating frame, and the operating ports are set to correspond with the leveling components. Multiple heat insulation plates are set between the receiving frame and the rotating frame, and the heat insulation plates are set close to the rotating frame.

[0014] This invention also discloses a method for testing the heat resistance of polyurethane materials. Based on the aforementioned heat resistance testing device for polyurethane materials, the testing method includes the following steps: S1. Start the stepper motor to drive the lifting fork to move upward, and the lifting fork lifts the basket so that the loading lever is in an unloaded state. S2. Start the drive motor. The drive motor drives the winding roller to rotate, so that the winding roller overcomes the tension of the first spring to wind or release the pull rope, so that the counterweight can slide in the slide block and change the position of the counterweight on the lever, so that the lever can be finely adjusted for counterweight until the tilt sensor detects that the lever is in a horizontal state. S3. Open the insulation door, place the polyurethane sample on the support assembly, and rotate the rotating frame to rotate the operating port to the position of the leveling assembly. S4. Press down the connecting ring to release the outer toothed ring from locking the inner toothed ring. Turn the knob to control the threaded rod to move up and down in the receiving cylinder, so that the contact head contacts the bottom of the base and pushes the bottom of the base, so that the ball seat swings at a certain angle on the ball head rod. By adjusting the three threaded rods, the levelness of the base is adjusted. S5. After the adjustment is completed, loosen the connecting ring. Under the elastic force of the second spring, the outer toothed ring moves up and engages with the inner toothed ring, locking the threaded rod and preventing it from rotating. S6. Close the insulation door, heat up the inner cavity of the hot air box, and stabilize the inner cavity temperature at the set temperature required for polyurethane sample testing. S7. Start the stepper motor. The stepper motor drives the lead screw to rotate at a low speed, which causes the nut to drive the lifting fork to descend at an extremely low speed. The cantilever rod on the hanging basket gradually contacts the hook until the centering groove on the cantilever rod aligns and engages with the fitting block on the hook. At this time, the hanging basket is completely hooked by the hook, and the silicone pad on the lifting fork begins to detach from the bottom of the hanging basket. The gravity of the weights on the hanging basket is quasi-statically transmitted to the pressure head through the connecting rod on the lever and applied to the polyurethane sample, realizing accurate detection of the polyurethane sample.

[0015] The present invention employs the above-mentioned technical solution, which is ingeniously conceived and rationally structured. It enables the hanging basket to descend at an extremely low and constant speed, allowing the weight of the weight to be smoothly transferred to the load-bearing end of the lever. During this process, the force of the weight increases gradually from zero to full load, completely eliminating the kinetic energy impact on the polyurethane sample at the moment of contact. This effectively prevents the polyurethane sample from collapsing instantly due to sudden force, ensuring that the measured softening temperature truly reflects the heat resistance of the material. It greatly improves the repeatability of data from the same batch of samples, thereby improving the accuracy of the test and the validity of the data.

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of the internal structure of an embodiment of the present invention; Figure 3 This is a schematic diagram of the automatic loading module in an embodiment of the present invention; Figure 4 This is an exploded structural diagram of the leveling mechanism in an embodiment of the present invention; Figure 5 This is an exploded view of the loading component and the lifting mechanism in an embodiment of the present invention; Figure 6 This is a schematic diagram of the leveling module in an embodiment of the present invention; Figure 7 This is an exploded view of the leveling component in an embodiment of the present invention.

[0018] In the diagram: 1-Hot air box; 2-Insulation door; 3-Expansion compartment; 4-Air outlet; 5-Base; 6-Support; 7-Pressure head; 8-Automatic loading module; 801-Fixed seat; 802-Lever; 803-Tilt sensor; 804-Shaft; 805-Ball bearing; 806-Winding roller; 807-Drive motor; 808-Pull rope; 809-Guide roller; 810-Slide block; 811-Counterweight block; 812-First spring; 813-Hook; 814-Matching block; 815-Cantilever rod; 816-Center groove; 817-Hanging basket; 818-Center rod; 819-Weight; 820-Lifting fork; 821-Silicone pad; 822-Sleeve; 823-Isolation cover; 824-Guide rail; 825-Stepper motor; 826-Lead screw; 827-Nut; 828-Connecting block; 9-Leveling module; 901-Ball seat; 902-Ball head rod; 903-Fixing plate; 904-Rotating frame; 905-Heat insulation plate; 906-Operating port; 907-Heat insulation ring; 908-Receiving cylinder; 909-Threaded rod; 910-Contact head; 911-Knob; 912-Internal toothed ring; 913-Connecting ring; 914-Second spring; 915-External toothed ring; 916-Receiving frame; 10-Polyurethane sample; 11-Connecting rod. Detailed Implementation

[0019] like Figure 1-7 As shown, a heat resistance testing device for polyurethane materials includes a hot air box 1, an insulated door 2 on the hot air box 1, an expansion chamber 3 fixedly connected to one side of the hot air box 1, a base 5 inside the hot air box 1, a support assembly for placing a polyurethane sample 10 on the top of the base 5, a lever 802 above the support assembly, the lever 802 being rotatably connected to the hot air box 1 via a connecting assembly, a pressure head 7 fixedly connected to the bottom of the lever 802 via a connecting rod 11, the pressure head 7 being positioned directly above the support assembly, one end of the lever 802 near the expansion chamber 3 extending into the expansion chamber 3 and equipped with a leveling mechanism for leveling the lever 802, a loading assembly at the end of the lever 802 away from the expansion chamber 3, a lifting mechanism below the loading assembly, and a leveling module 9 for leveling the polyurethane sample 10 below the base 5.

[0020] This design, through the coordination of the lifting mechanism and the loading component, enables the loading component to descend stably at extremely high speed, allowing the weight of the loading component to smoothly transition to the bearing end of the lever 802. This completely eliminates the kinetic energy impact at the moment of contact between the pressure head 7 and the polyurethane sample 10, effectively protecting the polyurethane sample 10 that has reached its softening temperature. It effectively prevents the polyurethane sample 10 from collapsing instantly due to sudden force, ensuring that the measured softening temperature truly reflects the heat resistance of the material. This greatly improves the repeatability of data from the same batch of samples, thereby enhancing the accuracy of the test and the validity of the data.

[0021] The lever 802, leveling mechanism, loading component and lifting mechanism constitute the automatic loading module 8, which is suitable for the automatic loading process of the device.

[0022] The support assembly includes two supports 6 arranged symmetrically, and the supports 6 are fixedly connected to the base 5.

[0023] Both supports 6 have support rollers rotatably connected to their upper ends.

[0024] The connecting assembly includes two fixed seats 801, which are respectively located on both sides of the lever 802 and fixedly connected to the hot air box 1. A shaft 804 is rotatably connected between the two fixed seats 801, and the shaft 804 is fixedly connected to the lever 802.

[0025] The shaft 804 is rotatably connected to the fixed seat 801 via a ball bearing 805.

[0026] The ball bearing 805 preferably uses a ceramic ball bearing, which has the advantages of oil-free self-lubrication, low coefficient of thermal expansion, and resistance to electromagnetic interference, thus ensuring the accurate detection of polyurethane sample 10 by this device.

[0027] In this embodiment, the shaft 804 is fixed between two fixed seats 801 and rotatably connected to the lever 802.

[0028] The leveling mechanism includes a slide block 810, which is fixedly connected to the bottom of the lever 802, and a counterweight block 811 is slidably connected inside the slide block 810.

[0029] A mounting base is fixedly connected above the lever 802. A winding roller 806 is rotatably connected to the mounting base. A pulling rope 808 is wound around the winding roller 806. One end of the pulling rope 808 is fixedly connected to the winding roller 806, and the other end of the pulling rope 808 passes around the guide roller 809 and is fixedly connected to the counterweight 811.

[0030] The 808 steel wire rope is the preferred choice for the traction rope.

[0031] The guide roller 809 is rotatably connected to the end of the lever 802 away from the loading assembly.

[0032] A drive motor 807 is fixedly mounted on the lever 802. The output end of the drive motor 807 is connected to the winding roller 806 for transmission. The drive motor 807 is electrically connected to the control system of the device.

[0033] The counterweight 811 has a first spring 812 fixedly connected to one end away from the pulling rope 808. The first spring 812 is located inside the slide block 810, and the other end of the first spring 812 is fixedly connected to the slide block 810.

[0034] An inclination sensor 803 is installed on the lever 802 near the connecting component, and the inclination sensor 803 is electrically connected to the control system of the device.

[0035] This design, through the closed-loop control of the tilt sensor 803 to precisely displace the counterweight 811, achieves automatic and precise zeroing of the lever 802's initial balance, eliminating system errors caused by operations such as changing the pressure head 7.

[0036] The loading component includes a hook 813, the upper end of which is rotatably connected to a lever 802, and the lower end of which is fixedly connected to a fitting block 814.

[0037] A hanging basket 817 is provided below the hook 813. A cantilever rod 815 is fixed above the hanging basket 817 by two connecting plates. A centering groove 816 is provided in the middle of the cantilever rod 815, and the centering groove 816 is correspondingly set with the fitting block 814.

[0038] A center rod 818 is fixed at the center of the hanging basket 817, and a weight 819 is fitted on the center rod 818.

[0039] The lifting mechanism includes a lifting fork 820. An isolation cover 823 is fixedly connected to the inner wall of the hot air box 1. The lifting fork 820 is slidably connected to the isolation cover 823 via two guide rails 824. A sleeve 822 is fixedly connected to the lower end of the lifting fork 820. A lead screw 826 is sleeved inside the sleeve 822. The lead screw 826 is rotatably connected to the hot air box 1 via a connecting block 828. A nut 827 is threaded onto the lead screw 826. The nut 827 is fixedly connected to the sleeve 822.

[0040] A stepper motor 825 is fixedly installed inside the isolation cover 823. The output end of the stepper motor 825 is connected to the lead screw 826 for transmission. The stepper motor 825 is electrically connected to the control system of the device.

[0041] Silicone pads 821 are attached to all four claws of the lifting fork 820.

[0042] This design, via a stepper motor 825 driving a lead screw 826 to rotate, allows the lifting fork 820 to descend smoothly at an extremely low speed. This causes the cantilever rod 815 on the weight basket 817 to slowly contact and accurately engage with the hook 813, ultimately detaching gently via a silicone pad 821. This process quasi-statically transfers the gravity of the weight 819 to the pressure head 7, eliminating the dynamic impact on the softened polyurethane sample 10 caused by traditional hanging methods, preventing the sample from being crushed instantly, and thus ensuring the authenticity and repeatability of the softening temperature measurement.

[0043] The leveling module 9 includes a ball seat 901 and a ball head rod 902. The ball seat 901 is fixedly connected to the base 5, and the ball head rod 902 is fixedly connected to the hot air box 1. The ball head of the ball head rod 902 is located in the hemispherical mounting groove of the ball seat 901.

[0044] A fixed plate 903 is fixedly connected inside the hot air box 1. Three leveling components are provided on the fixed plate 903. The three leveling components are arranged in a ring around the axis of the ball head rod 902.

[0045] The leveling assembly includes a receiving cylinder 908, which is fixedly connected to a fixed plate 903. The upper end of the receiving cylinder 908 is rotatably connected to a knob 911 via a bearing. The knob 911 is internally threaded to a threaded rod 909. The upper end of the threaded rod 909 is fixedly connected to a contact head 910, which is in close contact with the bottom surface of the base 5.

[0046] A connecting ring 913 is slidably sleeved on the receiving cylinder 908. An external toothed ring 915 is fixedly connected to the upper end of the connecting ring 913, and an internal toothed ring 912 is fixedly connected to the lower end of the knob 911. The external toothed ring 915 and the internal toothed ring 912 are arranged correspondingly.

[0047] A second spring 914 is fitted on the receiving cylinder 908, and the two ends of the second spring 914 are fixedly connected to the fixed plate 903 and the connecting ring 913, respectively.

[0048] A heat insulation ring 907 is fixedly connected to the top of the fixed plate 903 via a receiving frame 916. A rotating frame 904 is rotatably connected to the outside of the heat insulation ring 907. Three operating ports 906 are provided on the rotating frame 904, and the three operating ports 906 are correspondingly set with three leveling components.

[0049] Three heat insulation plates 905 are provided between the receiving frame 916 and the rotating frame 904. The three heat insulation plates 905 are arranged alternately with the three leveling components, and the heat insulation plates 905 are set close to the rotating frame 904.

[0050] The leveling module 9 is applicable to the leveling process of the base 5, support components and polyurethane sample 10.

[0051] This design allows the rotating frame 904 to be moved to the leveling component position in conjunction with the operation port 906, enabling convenient operation of the leveling component. After adjustment, the operation port 906 can be sealed by the heat insulation plate 905, which protects the internal leveling component from high-temperature radiation and dust, while also ensuring the overall heat insulation performance of the machine.

[0052] The three-point independent adjustment mechanism based on the ball joint 902 and ball seat 901 as an intermediate support and the leveling component can accurately compensate for the unevenness between the base 5 and the ground, ensuring that the support component remains absolutely level. This is crucial for the easily deformable polyurethane sample 10 under high-sensitivity loading, and can effectively avoid the indenter 7 being overloaded and the measurement data being distorted due to the initial tilt of the polyurethane sample 10.

[0053] The reset locking structure of the external gear ring 915 and the internal gear ring 912 enables instant mechanical locking after adjustment, resists micro-vibrations during the test, prevents the threaded rod 909 from loosening, and ensures the long-term stability of horizontal accuracy.

[0054] In addition to this embodiment, the number of leveling components, operation ports 906, and heat insulation plates 905 can be more than three.

[0055] The hot air box 1 is equipped with a heating device for raising the temperature of the polyurethane sample 10.

[0056] An air outlet 4 is provided on the side wall of the hot air box 1.

[0057] This invention also discloses a method for testing the heat resistance of polyurethane materials, based on the aforementioned heat resistance testing device for polyurethane materials, comprising the following steps: S1. Start the stepper motor 825 to drive the lifting fork 820 to move upward. The lifting fork 820 lifts the hanging basket 817 so that the loading lever 802 is in an unloaded state. S2. Start the drive motor 807. The drive motor 807 drives the winding roller 806 to rotate, so that the winding roller 806 overcomes the tension of the first spring 812 to wind or release the pull rope 808, so that the counterweight block 811 can slide in the slide block 810 and change the position of the counterweight block 811 on the lever 802, so that the lever 802 can be finely adjusted until the tilt sensor 803 detects that the lever 802 is in a horizontal state. S3. Open the insulation door 2, place the polyurethane sample 10 on the support assembly, rotate the rotating frame 904 so that the operating port 906 rotates to the position of the leveling assembly, and the operating port 906 is disengaged from the heat insulation plate 905. S4. Press down the connecting ring 913 to release the locking of the internal gear ring 912 by the external gear ring 915 connected to the connecting ring 913. Rotate the knob 911 to control the threaded rod 909 to move up and down in the receiving cylinder 908, so that the contact head 910 contacts the bottom of the base 5 and pushes the bottom of the base 5, so that the ball seat 901 swings at a certain angle on the ball head rod 902. Through the coordination and adjustment of the three threaded rods 909, the levelness of the base 5 is adjusted. S5. After the adjustment is completed, loosen the connecting ring 913. Under the elastic force of the second spring 914, the outer toothed ring 915 moves up and engages with the inner toothed ring 912, locking the threaded rod 909 so that the threaded rod 909 no longer rotates. S6. Close the door 2, heat the inner cavity of the hot air box 1, and stabilize the inner cavity temperature at the set temperature required for the testing of polyurethane sample 10. S7. Start the stepper motor 825. The stepper motor 825 drives the lead screw 826 to rotate at a low speed, so that the nut 827 drives the lifting fork 820 constrained by the guide rail 824 to descend at an extremely low speed. The cantilever rod 815 on the hanging basket 817 gradually contacts the hook 813 until the centering groove 816 on the cantilever rod 815 aligns and engages with the fitting block 814 on the hook 813. At this time, the hanging basket 817 is completely hooked by the hook 813. The silicone pad 821 on the lifting fork 820 begins to detach from the bottom of the hanging basket 817. The weight 819 on the hanging basket 817 is quasi-statically transmitted to the pressure head 7 through the connecting rod 11 on the lever 802 and applied to the polyurethane sample 10 to achieve accurate detection of the polyurethane sample 10.

[0058] For those skilled in the art, any changes, modifications, substitutions, and variations made to the embodiments without departing from the principles and spirit of the present invention, based on the teachings of the present invention, still fall within the protection scope of the present invention.

Claims

1. A heat resistance testing device for polyurethane materials, comprising a hot air box (1), characterized in that: The hot air box (1) is provided with an insulated door (2), an expansion chamber (3) is fixedly connected to one side of the hot air box (1), a base (5) is provided inside the hot air box (1), a support assembly for placing polyurethane sample (10) is provided above the base (5), a lever (802) is provided above the support assembly, the lever (802) is rotatably connected to the hot air box (1), a pressure head (7) is fixedly connected below the lever (802) through a connecting rod (11), the end of the lever (802) near the expansion chamber (3) extends into the expansion chamber (3) and is provided with a leveling mechanism for leveling the lever (802), a loading assembly is provided at the end of the lever (802) away from the expansion chamber (3), a lifting mechanism is provided below the loading assembly, and a leveling module (9) for leveling polyurethane sample (10) is provided below the base (5).

2. The heat resistance testing device for polyurethane materials according to claim 1, characterized in that: The leveling mechanism includes a sliding block (810), which is fixedly connected to the lower part of the lever (802). A counterweight (811) is slidably connected inside the sliding block (810). A winding roller (806) is rotatably connected above the lever (802). A pulling rope (808) is wound on the winding roller (806). One end of the pulling rope (808) is fixedly connected to the winding roller (806), and the other end of the pulling rope (808) passes around the guide roller (809) installed on the lever (802) and is fixedly connected to the counterweight (811).

3. The heat resistance testing device for polyurethane materials according to claim 2, characterized in that: The counterweight (811) is fixedly connected to a first spring (812) at one end away from the pulling rope (808), and the other end of the first spring (812) is fixedly connected to the slide block (810). A drive motor (807) is fixedly installed on the lever (802), and the output end of the drive motor (807) is connected to the winding roller (806) for transmission.

4. The heat resistance testing device for polyurethane materials according to claim 3, characterized in that: The loading component includes a hook (813), the upper end of which is rotatably connected to a lever (802), the lower end of which is fixedly connected to a fitting block (814), a hanging basket (817) is provided below the hook (813), a cantilever rod (815) is fixedly connected above the hanging basket (817), a centering groove (816) is provided at the middle position of the cantilever rod (815), the centering groove (816) is correspondingly set to the fitting block (814), a center rod (818) is fixedly connected at the center position of the hanging basket (817), and a weight (819) is sleeved on the center rod (818).

5. The heat resistance testing device for polyurethane materials according to claim 4, characterized in that: The lifting mechanism includes a lifting fork (820), an isolation cover (823) is fixedly connected to the inner wall of the hot air box (1), the lifting fork (820) is slidably connected to the isolation cover (823) through two guide rails (824), a sleeve (822) is fixedly connected to the lower end of the lifting fork (820), a lead screw (826) is sleeved inside the sleeve (822), the lead screw (826) is rotatably connected to the hot air box (1) through a connecting block (828), a nut (827) is threaded on the lead screw (826), the nut (827) is fixedly connected to the sleeve (822), and a stepper motor (825) is fixedly installed inside the isolation cover (823), the output end of the stepper motor (825) is connected to the lead screw (826) for transmission.

6. The heat resistance testing device for polyurethane materials according to claim 5, characterized in that: Silicone pads (821) are attached to the four claws of the lifting fork (820).

7. The heat resistance testing device for polyurethane materials according to claim 6, characterized in that: The leveling module (9) includes a ball seat (901) and a ball head rod (902). The ball seat (901) is fixedly connected to the base (5), and the ball head rod (902) is fixedly connected to the hot air box (1). The ball head of the ball head rod (902) is located in the hemispherical mounting groove of the ball seat (901). A fixed plate (903) is fixedly connected inside the hot air box (1). Multiple leveling components are provided on the fixed plate (903). The multiple leveling components are arranged in a ring around the axis of the ball head rod (902).

8. The heat resistance testing device for polyurethane materials according to claim 7, characterized in that: The leveling assembly includes a receiving cylinder (908), which is fixedly connected to a fixed plate (903). The upper end of the receiving cylinder (908) is rotatably connected to a knob (911) via a bearing. The knob (911) is internally threaded to a threaded rod (909). The upper end of the threaded rod (909) is fixedly connected to a contact head (910), which is in close contact with the bottom surface of the base (5). A connecting ring (913) is slidably sleeved on the receiving cylinder (908). An external toothed ring (915) is fixedly connected to the upper end of the connecting ring (913), and an internal toothed ring (912) is fixedly connected to the lower end of the knob (911). The external toothed ring (915) and the internal toothed ring (912) are correspondingly arranged. A second spring (914) is sleeved on the receiving cylinder (908), and the two ends of the second spring (914) are fixedly connected to the fixed plate (903) and the connecting ring (913) respectively.

9. A heat resistance testing device for polyurethane materials according to claim 8, characterized in that: A heat insulation ring (907) is fixedly connected to the top of the fixed plate (903) via a receiving frame (916). A rotating frame (904) is rotatably connected to the outside of the heat insulation ring (907). Multiple operating ports (906) are provided on the rotating frame (904). The operating ports (906) are correspondingly set with the leveling components. Multiple heat insulation plates (905) are set between the receiving frame (916) and the rotating frame (904). The heat insulation plates (905) are set close to the rotating frame (904).

10. A method for testing the heat resistance of polyurethane materials, based on the heat resistance testing device for polyurethane materials according to claim 9, characterized in that: Includes the following steps: S1. Start the stepper motor (825) to drive the lifting fork (820) to move upward. The lifting fork (820) lifts the hanging basket (817) so that the loading lever (802) is in an unloaded state. S2. Start the drive motor (807). The drive motor (807) drives the winding roller (806) to rotate, so that the winding roller (806) overcomes the tension of the first spring (812) to wind or release the pull rope (808), so that the counterweight (811) can slide in the slide block (810) and change the position of the counterweight (811) on the lever (802), so that the lever (802) can be finely adjusted until the tilt sensor (803) detects that the lever (802) is in a horizontal state. S3. Open the insulation door (2), place the polyurethane sample (10) on the support assembly, and rotate the rotating frame (904) to rotate the operating port (906) to the position of the leveling assembly; S4. Press down the connecting ring (913) to release the lock of the external gear ring (915) on the internal gear ring (912). Turn the knob (911) to control the threaded rod (909) to move up and down in the receiving cylinder (908) so that the contact head (910) contacts the bottom of the base (5) and pushes the bottom of the base (5) so that the ball seat (901) swings at a certain angle on the ball head rod (902). Through the coordination and adjustment of the three threaded rods (909), the level of the base (5) is adjusted. S5. After the adjustment is completed, loosen the connecting ring (913). Under the elastic force of the second spring (914), the outer toothed ring (915) moves up and engages with the inner toothed ring (912), locking the threaded rod (909) so that the threaded rod (909) no longer rotates. S6. Close the insulation door (2), heat the inner cavity of the hot air box (1), and stabilize the inner cavity temperature at the set temperature required for the polyurethane sample (10) test. S7. Start the stepper motor (825). The stepper motor (825) drives the lead screw (826) to rotate at a low speed, so that the nut (827) drives the lifting fork (820) to descend at a very low speed. The cantilever rod (815) on the hanging basket (817) gradually contacts the hook (813) until the centering groove (816) on the cantilever rod (815) aligns and engages with the fitting block (814) on the hook (813). At this time, the hanging basket (817) is completely hooked by the hook (813). The silicone pad (821) on the lifting fork (820) begins to detach from the bottom of the hanging basket (817). The weight (819) on the hanging basket (817) is quasi-statically transmitted to the pressure head (7) through the connecting rod (11) on the lever (802) and applied to the polyurethane sample (10) to achieve accurate detection of the polyurethane sample (10).

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