A load holding test device for nuts

Abstract

The present invention relates to the technical field of load test equipment, and specifically provides a load holding test equipment for nuts, including a frame, on which an upper tooling and a lower tooling are arranged, the upper tooling and the lower tooling provide a pulling force to pull a threaded rod and a nut to be tested away from each other, an upper top plate and a lower top plate are respectively arranged on the upper and lower end surfaces of the nut to be tested, the lower top plate is provided with an internal thread whose diameter gradually increases from top to bottom along the axial direction, and only the top of the internal thread is completely matched with the external thread on the outer periphery of the threaded rod, before the nut to be tested is matched with the external thread, the internal thread on the lower top plate can scrape off the debris remaining on the surface of the external thread of the threaded rod, and the scraped debris will be discharged through the gap between the external thread and the internal thread, thereby avoiding the nut to be tested from being affected by metal debris during the load holding test, thereby ensuring the accuracy of the test results.

Description

Technical Field

[0001] The invention relates to the technical field of load test equipment, in particular to a load holding test equipment for nuts. Background Art

[0002] Nut load holding test equipment is usually used to test the performance of nuts under specified loads, including their tensile strength, fatigue strength and locking performance. Among them, the equipment for detecting tensile strength is mainly used to test the performance of nuts under specific tensile forces to verify whether they meet the design requirements. Such equipment usually takes high precision and stability as core requirements. For example, Chinese patent CN211061318U discloses a high-strength nut load holding test fixture, which makes the installation of nuts more convenient by flexibly adjusting the spacing between fixed mounting parts and movable mounting parts. It is also suitable for nuts of different shapes, and can complete load holding tests for nuts of different specifications.

[0003] However, in the above scheme, when performing multiple nut load holding tests, the surface threads of the screw connected to the nut are easily worn and damaged, and require irregular maintenance or replacement. Therefore, the later maintenance costs are high, and when the screw is used many times, there will be some test nut debris on the threads of the screw, which can easily make the threads more easily damaged and cause inaccurate test results. In severe cases, the nut may burst out, endangering the safety of equipment and personnel. Summary of the invention

[0004] Based on this, it is necessary to provide a load-keeping test equipment for nuts to address the wear problem of the internal threads of the current test nuts.

[0005] The above purpose is achieved through the following technical solutions:

[0006] A load holding test device for nuts, comprising:

[0007] A frame, wherein an upper tooling and a lower tooling are provided on the frame, and a threaded rod and a nut to be tested are detachably mounted on the upper tooling and the lower tooling, respectively, and the upper tooling and the lower tooling are separated from each other to apply tension to the threaded rod and the nut to be tested;

[0008] The outer circumference of the threaded rod is provided with an external thread along the axial direction, and the lower part of the external thread is a smooth part;

[0009] A fixture seat, the fixture seat comprises an upper top plate and a lower top plate which can move axially relative to each other, the upper top plate and the lower top plate wrap the nut to be tested to connect the lower fixture, the upper top plate is slidably connected to the threaded rod, the lower top plate has an internal thread, the diameter of the internal thread gradually increases from top to bottom along the axial direction of the threaded rod, and the top diameter of the internal thread is the same as the diameter of the internal thread of the nut to be tested;

[0010] When the nut to be tested is not connected to the threaded rod, the upper top plate and the lower top plate respectively abut against the upper and lower ends of the nut to be tested;

[0011] During the process of connecting the nut to be tested to the threaded rod, the lower top plate firstly screws through the external thread and then separates from the lower end surface of the nut to be tested and is located at the smooth part, and the nut to be tested is then screwed to the threaded rod.

[0012] Furthermore, the outer circumference of the threaded rod is provided with a plurality of sections of external threads along the axial direction, and the outer circumference diameter of the threaded rod where each section of external threads is located gradually increases from top to bottom along the axial direction, and the smooth portion is located between adjacent external threads.

[0013] Furthermore, the interior of the threaded rod is hollow and is spirally connected with a fixing rod, and the fixing rod can connect the threaded rod to the upper tooling.

[0014] Furthermore, a plurality of groups of connecting threads are arranged on the outer periphery of the fixing rod, and the diameter of the fixing rod where each group of connecting threads is located gradually decreases from top to bottom along the axial direction, and the rotation direction of each group of connecting threads is the same as the rotation direction of the external threads on the outer periphery of the threaded tube. The interior of the threaded rod is divided into a plurality of cavities with gradually decreasing diameters from top to bottom along the axial direction, and the plurality of cavities are threadedly matched with the plurality of groups of connecting threads.

[0015] Furthermore, a first hexagonal plate frame and a second hexagonal plate frame are fixedly arranged on the end surfaces of the upper top plate and the lower top plate that are close to each other, respectively. The inner periphery of the first hexagonal plate is in vertical sliding contact with the outer periphery of the second hexagonal plate frame, and the inner periphery of the second hexagonal plate is in vertical sliding contact with the outer periphery of the nut to be tested.

[0016] Furthermore, a spiral channel is provided on the side wall of the threaded rod, an inlet and an outlet of the spiral channel are both located near the bottom of the threaded rod, and the spiral channel can be filled with liquid nitrogen.

[0017] Furthermore, a hexagonal prism is fixedly connected to the bottom of the threaded rod, and the axis of the hexagonal prism coincides with the axis of the threaded rod.

[0018] Furthermore, a tensile testing machine is arranged on the frame, and the tensile testing machine is connected to the upper tooling and the lower tooling.

[0019] Furthermore, the tensile testing machine is provided with a control module, and the control module can regulate the tensile force of the tensile testing machine on the upper tooling and the lower tooling.

[0020] Furthermore, both the upper tooling and the lower tooling are provided with mounting grooves, and the length of the mounting groove of the lower tooling is greater than the length of the mounting groove of the upper tooling.

[0021] The beneficial effects of the present invention are:

[0022] The present invention arranges a lower top plate on the nut to be tested, and the lower top plate is provided with an internal thread whose diameter gradually increases from top to bottom along the axial direction, and only the top of the internal thread is completely matched with the external thread on the outer periphery of the threaded rod. Before the nut to be tested is matched with the external thread, the internal thread on the lower top plate can scrape off the debris remaining on the surface of the external thread of the threaded rod, and the scraped debris will be discharged through the gap between the external thread and the internal thread, so as to avoid the debris from wearing the internal thread of the nut to be tested and affecting the load holding test, thereby ensuring the accuracy of the test results.

[0023] The present invention arranges multiple sections of external threads with different diameters on the outer circumference of the threaded rod, so that the threaded rod can adapt to nuts to be tested of various specifications, thereby improving the practicality of the threaded rod. At the same time, the diameters of the multiple sections of external threads gradually increase from top to bottom, and smooth parts and bosses are provided between adjacent external threads. If the nut to be tested is unqualified and causes the nut to be tested to detach from the external threads, the nut to be tested will be abutted by the lower top plate, thereby preventing the nut to be tested from splashing out and detaching from the threaded rod, thereby avoiding safety accidents.

[0024] The present invention arranges a fixed rod to connect the threaded rod, and the multiple groups of connecting threads on the outer periphery of the fixed rod have the same rotation direction as the multiple sections of external threads on the outer periphery of the threaded rod, which can facilitate the installation of the threaded rod, the fixed rod and the nut to be tested, improve the installation efficiency, and prevent the fixed rod and the threaded rod from rotating relative to each other and loosening when the nut to be tested is subjected to a load holding test, thereby improving the accuracy of the experiment.

[0025] The present invention provides a spiral channel on the side wall of the threaded rod. When the nut to be tested is unqualified and difficult to remove from the threaded rod, liquid nitrogen is introduced into the inlet of the spiral channel to reduce the overall size of the threaded rod, thereby reducing the difficulty of removing the nut to be tested. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic structural diagram of a load holding test device for nuts provided in one embodiment of the present invention;

[0027] Figure 2 A schematic structural diagram of an upper tooling and a lower tooling of a load-keeping test device for nuts provided in one embodiment of the present invention;

[0028] Figure 3 for Figure 2 A front view of the upper fixture and the lower fixture structure of the load holding test equipment for nuts provided in one embodiment;

[0029] Figure 4 A schematic diagram of a fixing rod structure of a load-keeping test device for nuts provided in one embodiment of the present invention;

[0030] Figure 5 A schematic cross-sectional view of a threaded rod of a load-keeping test device for nuts provided in one embodiment of the present invention;

[0031] Figure 6 A cross-sectional view of a fixture seat and a nut to be tested of a load-keeping test device for nuts provided in one embodiment of the present invention;

[0032] Figure 7 A schematic diagram of a first installation state of a load holding test device for nuts provided in one embodiment of the present invention;

[0033] Figure 8 A schematic diagram of a second installation state of a load holding test device for nuts provided in one embodiment of the present invention;

[0034] Fig. 9 A schematic diagram of a third installation state of a load holding test device for nuts provided in one embodiment of the present invention;

[0035] Fig.10 A schematic diagram of a fourth installation state of a load holding test device for nuts provided in one embodiment of the present invention.

[0036] in:

[0037] 100, frame; 110, upper tooling; 111, first mounting slot; 120, lower tooling; 121, second mounting slot; 130, tensile machine; 140, control module;

[0038] 200, threaded rod; 210, external thread; 220, smooth portion; 230, boss; 240, cavity; 250, spiral channel; 251, inlet; 252, outlet; 260, hexagonal prism; 270, fixing rod; 280, connecting thread;

[0039] 300, fixture seat; 310, upper top plate; 311, round hole; 312, first hexagonal plate frame; 320, lower top plate; 321, through groove; 322, second hexagonal plate frame;

[0040] 400. Nut to be tested. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in the present invention, unless otherwise specified, include direct and indirect connections (couplings). In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0043] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0044] Refer to the following Figure 1-Figure 10 To describe a load holding test device for nuts provided by the present invention.

[0045] A load holding test device for nuts is suitable for load holding tests of nuts, comprising a frame 100, on which an upper tooling 110 and a lower tooling 120 are arranged, on which a threaded rod 200 and a nut 400 to be tested are detachably mounted, respectively. The load holding test of the nut 400 to be tested is to apply tension to the threaded rod 200 and the nut 400 to be tested that are threadedly connected together by the upper tooling 110 and the lower tooling 120, the tension gradually increases to a test tension value and lasts for a certain period of time, and after the test is completed, the nut 400 to be tested is taken out and the state of its internal threads is observed. If the state is abnormal, it means that the tension that the nut 400 to be tested can withstand is lower than the test tension, and the nut 400 to be tested is unqualified. If the state of the internal threads is normal, it means that the tension that the nut 400 to be tested can withstand is equal to or higher than the test tension, so the nut 400 to be tested is qualified.

[0046] When carrying out load holding tests on the nuts 400 to be tested for multiple times, the same threaded rod 200 is usually used to test multiple nuts 400 to be tested. Generally, multiple nuts produced in the same batch are selected for multiple tests. An external thread 210 is axially arranged on the outer periphery of the threaded rod 200. The strength of the external thread 210 of the threaded rod 200 used in the test is much greater than the strength of the internal thread of the nut 400 to be tested, so that the same threaded rod 200 can be used for a long time. Therefore, there may be some debris of the nuts 400 to be tested on the external thread 210 of the threaded rod 200, which can easily make the internal thread of the nut 400 to be tested more easily damaged and cause inaccurate test results.

[0047] The present invention solves the above problem by setting a fixture seat 300, which includes an upper top plate 310 and a lower top plate 320. The upper top plate 310 and the lower top plate 320 wrap the nut 400 to be tested so that it can be connected to the lower tooling 120, that is, the upper top plate 310 is located on the upper end surface of the nut 400 to be tested, and the lower top plate 320 is located on the lower end surface of the nut 400 to be tested. The upper top plate 310 is provided with a circular hole 311, and the lower top plate 320 is provided with a circular hole 312. A through groove 321 is provided on the top, and an internal thread is provided on the inner wall of the through groove 321. The diameter of the internal thread of the lower top plate 320 gradually increases from top to bottom along the axial direction, and the diameter of the top end of the internal thread of the lower top plate 320 is the same as the diameter of the internal thread of the nut 400 to be tested. The circular hole 311 of the upper top plate 310, the nut 400 to be tested and the through groove 321 of the lower top plate 320 are all coaxial, and the lower end of the external thread 210 of the threaded rod 200 has a smooth portion 220.

[0048] When performing a load holding test on the nut 400 to be tested, the nut 400 to be tested needs to be placed between the upper top plate 310 and the lower top plate 320, with the upper top plate 310 abutting against the upper end surface of the nut 400 to be tested, and the lower top plate 320 abutting against the lower end surface of the nut 400 to be tested. In the process of installing the nut 400 to be tested onto the external thread 210 of the threaded rod 200, as shown in FIG. Figure 8 and Fig. 9As shown in the figure, the internal thread of the lower top plate 320 will first contact the external thread 210 on the threaded rod 200. Since the lower top plate 320 and the nut 400 to be tested move from top to bottom relative to the threaded rod 200, and the internal thread diameter of the lower top plate 320 gradually increases from top to bottom, when the internal thread of the lower top plate 320 is matched with the external thread 210 of the threaded rod 200, a gap will be generated between the internal thread of the lower top plate 320 and the external thread 210, but the top of the internal thread of the lower top plate 320 is completely matched with the external thread 210. As the lower top plate 320 moves from top to bottom relative to the threaded rod 200 and the two rotate relative to each other, the internal thread on the lower top plate 320 can scrape off the debris remaining on the surface of the external thread 210 of the threaded rod 200, and the scraped debris will be discharged through the gap between the external thread 210 of the threaded rod 200 and the internal thread of the lower top plate 320, thereby preventing the internal thread of the nut 400 to be tested from being worn by the debris, reducing the influence of the metal debris on the nut 400 to be tested during the load holding test, and thus ensuring the accuracy of the test results.

[0049] It should be noted that, after the lower top plate 320 cleans the external thread 210 of the threaded rod 200, the lower top plate 320 will be located at the smooth portion 220 below the external thread 210, such as Fig.10 As shown, at this time, the lower top plate 320 is separated from the lower end surface of the nut 400 to be tested, and the nut 400 to be tested has been completely spirally connected to the external thread 210, and the upper tooling 110 and the lower tooling 120 are separated from each other so as to perform a load holding test on the threaded rod 200 and the nut 400 to be tested. Separating the lower top plate 320 from the lower end surface of the nut 400 to be tested can avoid the influence of the lower top plate 320 on the experimental results. If the lower top plate 320 is not separated from the lower end surface of the nut 400 to be tested during the experiment, the lower top plate 320 will share part of the tensile force on the nut 400 to be tested, thereby causing inaccurate experimental results, that is, the originally unqualified nut 400 to be tested is detected as qualified.

[0050] In a further embodiment, a plurality of sections of external threads 210 are axially arranged on the outer periphery of the threaded rod 200, and the diameter of the threaded rod 200 where each section of the external thread 210 is located gradually increases from top to bottom, and the smooth portion 220 is located between adjacent external threads 210, and a boss 230 is provided between each section of the external thread 210 and the upper smooth portion 220, so that when the lower top plate 320 is located on the smooth portion 220, it can abut against the boss 230 with a larger diameter below. If the nut 400 to be tested is unqualified and causes the nut 400 to be tested to detach from the external thread 210, the nut 400 to be tested will be abutted by the lower top plate 320, thereby preventing the nut 400 to be tested from splashing out of the threaded rod 200 and avoiding safety accidents.

[0051] It should be noted that by setting multiple sections of external threads 210, it is possible to adapt to a variety of different specifications of nuts 400 to be tested, for example, commonly used specifications include M8, M10, M12, M14, M16, M20, M24 and M36, etc. When installing nuts 400 to be tested of different specifications, the upper top plate 310 and the lower top plate 320 also need to be replaced, so as to ensure that the nut 400 to be tested can be correctly installed on the lower tooling 120, and ensure that the lower top plate 320 can clean the external threads 210 of the corresponding specifications, and also ensure that the circular hole 311 of the upper top plate 310 can pass the threaded rod 200 of the corresponding diameter.

[0052] In a further embodiment, the interior of the threaded rod 200 is hollow and is spirally connected to a fixing rod 270 , one end of the fixing rod 270 can be installed in the upper tooling 110 , and the other end of the fixing rod 270 is spirally connected to the interior of the threaded rod 200 , thereby connecting the threaded rod 200 to the upper tooling 110 .

[0053] Specifically, multiple groups of connecting threads 280 are axially arranged on the outer periphery of the fixing rod 270, and the diameter of the fixing rod 270 where each group of connecting threads 280 is located gradually decreases from top to bottom along the axial direction. The diameter change of the fixing rod 270 is opposite to the diameter change of the threaded rod 200, and the interior of the threaded rod 200 is hollow, and the interior is divided into multiple cavities 240 with gradually decreasing diameters from top to bottom along the axial direction. The multiple cavities 240 are adapted to the multiple groups of connecting threads 280 on the outer periphery of the fixing rod 270, that is, the inner walls of the multiple cavities 240 are provided with internal threads that cooperate with the multiple groups of connecting threads 280 on the outer periphery of the fixing rod 270. When the fixing rod 270 is inserted into the threaded rod 200, the bottom of each group of connecting threads 280 on the fixing rod 270 contacts the upper end of the internal threads of the corresponding cavity 240. At this time, the fixing rod 270 can be matched with the threaded rod 200 by rotating the threaded rod 200. It can be understood that when the threaded rod 200 rotates, the internal threads on the inner sides of the multiple cavities 240 are threadedly connected to the corresponding connecting threads 280 at the same time. That is to say, the multiple sets of connecting threads 280 on the fixed rod 270 can be spirally connected to the inside of the threaded rod 200 at the same time, so that the longer fixed rod 270 and the threaded rod 200 can be connected into place with fewer turns.

[0054] It should be noted that the plurality of connecting threads 280 on the outer periphery of the fixing rod 270 and the outer threads 210 on the outer periphery of the threaded rod 200 have the same rotation direction, and such a setting has the following effects:

[0055] First, it is convenient to install the threaded rod 200, the fixing rod 270 and the nut to be tested 400, thereby improving the installation efficiency.

[0056] When installing the threaded rod 200, the fixing rod 270 and the nut 400 to be tested, the upper end of the fixing rod 270 is first installed on the upper fixture 110, so that the fixing rod 270 and the upper fixture 110 are relatively stationary, and then the upper top plate 310 and the lower top plate 320 are both abutted against the upper and lower ends of the nut 400 to be tested, and the upper top plate 310, the nut 400 to be tested and the lower top plate 320 are connected to the lower fixture 120, so that the nut 400 to be tested and the lower fixture 120 are relatively stationary. The state at this time is as shown in FIG. Figure 7 Then, the threaded rod 200 is moved from bottom to top through the upper top plate 310, the nut 400 to be tested and the lower top plate 320, and the fixing rod 270 is inserted into the threaded rod 200. At this time, the outer thread 210 on the outer periphery of the threaded rod 200 does not correspond to the inner thread of the nut 400 to be tested, and the connecting thread 280 on the outer periphery of the fixing rod 270 corresponds to the inner thread of the cavity 240 inside the threaded rod 200. Finally, the threaded rod 200 is rotated, as shown in FIG. Figure 8 and Fig. 9 As shown, the threaded rod 200 only needs to be rotated in one direction to move the threaded rod 200 upward relative to the fixed rod 270, and the threaded rod 200 also moves upward relative to the nut 400 to be tested, so that the threaded rod 200, the fixed rod 270 and the nut 400 to be tested can be installed by rotating the threaded rod 200 a few times, saving time.

[0057] Secondly, it can prevent the fixed rod 270 and the threaded rod 200 from rotating relative to each other and becoming loose when the nut 400 to be tested is subjected to a load holding test, thereby improving the accuracy of the test.

[0058] Since the nut 400 to be tested is connected to the lower fixture 120 through the upper top plate 310 and the lower top plate 320, specifically, the upper end surface of the upper top plate 310 abuts against the lower fixture 120, when the upper fixture 110 and the lower fixture 120 pull the nut 400 to be tested and the fixing rod 270, the threaded rod 200 has a tendency to move away from the nut 400 to be tested, that is, the threaded rod 200 has a tendency to move upward relative to the nut 400 to be tested. At this time, the nut 400 to be tested is connected to the lower fixture 120 through the upper top plate 310, so the nut 400 to be tested and the lower fixture 120 are relatively stationary, so that the threaded rod 200 has a tendency to continue to rotate relative to the nut 400 to be tested (the rotation direction is the nut relative to the threaded rod 20 0 when the threaded rod 200 moves downward) and since the rotation direction of the connecting thread 280 on the periphery of the fixing rod 270 is the same as the rotation direction of the external thread 210 on the periphery of the threaded rod 200, and the fixing rod 270 is stationary relative to the upper tooling 110, the tendency of the threaded rod 200 to continue to rotate can make the threaded rod 200 have a tendency to move upward relative to the fixing rod 270, so that the threaded rod 200, the fixing rod 270 and the threaded rod 200 are closer to each other and will not move away from each other, thereby making the connection between the two tighter. Therefore, if the connecting thread 280 on the periphery of the fixing rod 270 is the same as the external thread 210 on the periphery of the threaded rod 200, it can prevent the fixing rod 270 and the threaded rod 200 from loosening during the experiment.

[0059] For example, refer to Fig. 9 , set the threaded rod 200 counterclockwise ( Fig. 9 The rotation of the threaded rod 200 (counterclockwise when viewed from top to bottom) can make the threaded rod 200 move upward relative to the fixed rod 270, and the threaded rod 200 move upward relative to the nut 400 to be tested. When the nut 400 to be tested is subjected to a load holding test, the lower tooling 120 pulls the nut 400 to be tested so that the threaded rod 200 has a tendency to move upward relative to the nut 400 to be tested. At this time, the threaded rod 200 has a tendency to continue to rotate counterclockwise, and the counterclockwise rotation of the threaded rod 200 will make the screw continue to move upward relative to the fixed rod 270. Therefore, the connection strength between the two will not be weakened, thereby avoiding the loosening of the fixed rod 270 and the threaded rod 200.

[0060] Specifically, in an embodiment of the present invention, in order to facilitate the upper top plate 310 and the lower top plate 320 to connect the nut 400 to be tested to the lower tooling 120, a first hexagonal plate frame 312 and a second hexagonal plate frame 322 are fixedly arranged on the end surfaces of the upper top plate 310 and the lower top plate 320 that are close to each other, respectively. The inner periphery of the first hexagonal plate frame 312 is slidably connected to the outer periphery of the second hexagonal plate frame 322 up and down, and the inner periphery of the second hexagonal plate frame is slidably connected to the outer periphery of the nut 400 to be tested up and down. The outer periphery of the nut 400 to be tested is also hexagonal. By installing the first hexagonal plate frame 312 on the upper top plate 310 on the lower tooling 120, the nut 400 to be tested can be connected to the lower tooling 120 and the nut 400 to be tested can be made stationary relative to the lower tooling 120.

[0061] In a further embodiment, Figure 5 As shown, a spiral channel 250 is opened on the side wall of the threaded rod 200, and the spiral channel 250 surrounds the side wall of the threaded rod 200. The inlet 251 and the outlet 252 of the spiral channel 250 are both arranged on the side wall near the bottom of the threaded rod 200. The spiral channel 250 is used to fill with liquid nitrogen. When the threaded rod 200 is working normally, liquid nitrogen is not introduced into the spiral channel 250. Only when the nut 400 to be tested is unqualified and it is difficult to remove it from the threaded rod 200, liquid nitrogen is introduced into the inlet 251 of the spiral channel 250. The liquid nitrogen (liquid nitrogen temperature is -196°C) passes through the spiral channel 250 to rapidly cool the side wall of the threaded rod 200. As the temperature of the threaded rod 200 made of metal decreases, the thermal expansion coefficient of the metal decreases, and the molecular distance of the metal decreases, resulting in a reduction in the overall size of the threaded rod 200, thereby reducing the difficulty of removing the nut 400 to be tested. After the nut 400 to be tested is removed, the liquid nitrogen is extracted from the outlet 252.

[0062] Specifically, a hexagonal prism 260 is fixedly provided at the bottom of the threaded rod 200 of the embodiment of the present invention. The hexagonal prism 260 is coaxially and fixedly connected to the threaded rod 200. The hexagonal prism 260 can be clamped by a wrench, and then the wrench is turned to drive the threaded rod 200 to rotate, which facilitates the installation of the threaded rod 200.

[0063] More specifically, a tensile testing machine 130 is provided on the frame 100, and the tensile testing machine 130 is connected to the upper tooling 110 and the lower tooling 120. When the tensile testing machine 130 is started, it can drive the upper tooling 110 and the lower tooling 120 to move away from or closer to each other. After the fixing rod 270, the threaded rod 200 and the nut 400 to be tested are installed, the upper tooling 110 and the lower tooling 120 are driven away from each other to start the load holding test of the nut 400 to be tested. A control module 140 is provided on the tensile testing machine 130. The control module 140 can adjust the tension of the tensile testing machine 130. The control module 140 is specifically a computer program that can adjust different tensions. The control module 140 can also detect and record experimental data, and determine whether the nut 400 to be tested is qualified according to the set program.

[0064] In a further embodiment, in order to facilitate the installation of the fixed rod 270, the threaded rod 200 and the nut to be tested 400, installation grooves are provided on the upper tooling 110 and the lower tooling 120. For the convenience of description, the installation groove of the upper tooling 110 is named as the first installation groove 111, and the installation groove of the lower tooling 120 is named as the second installation groove 121. The length of the second installation groove 121 is greater than the length of the first installation groove 111. This is because the threaded rod 200 needs to pass through the nut to be tested 400 from bottom to top, and the length of the threaded rod 200 is relatively long. Increasing the length of the second installation groove 121 facilitates the installation of the threaded rod 200.

[0065] The specific working process of a load holding test device for nuts provided by the present invention is described in combination with the above embodiments:

[0066] Install:

[0067] After adjusting the distance between the upper fixture 110 and the lower fixture 120, one end of the fixing rod 270 is clamped in the first mounting groove 111 of the upper fixture 110. Other components can be used to make the fixing rod 270 relatively stationary relative to the upper fixture 110. Then, the nut 400 to be tested is installed on the inner periphery of the second hexagonal plate frame 322 of the lower top plate 320, and the first hexagonal plate frame 312 of the upper top plate 310 is installed on the outer periphery of the second hexagonal plate frame 322. The installed upper top plate 310, the nut 400 to be tested and the lower top plate 320 are clamped in the second mounting groove 121 of the lower fixture 120. Other components can be used to make the upper top plate 310, the nut 400 to be tested and the lower top plate 320 stationary relative to the lower fixture 120. The specific state is as follows: Figure 7 Finally, the threaded rod 200 is passed through the lower top plate 320, the nut 400 to be tested, the upper top plate 310 and the fixing rod 270 from bottom to top in the second mounting groove 121. When the outer thread 210 on the outer periphery of the threaded rod 200 contacts the inner thread of the lower top plate 320, a wrench is clamped on the surface of the hexagonal prism 260 at the bottom of the threaded rod 200, and the operator drives the threaded rod 200 to rotate using the wrench.

[0068] Specific status such as Figure 8As shown, when the threaded rod 200 rotates, it moves upward, and the internal thread of the lower top plate 320 contacts the external thread 210 corresponding to the threaded rod 200, so that the lower top plate 320 moves downward relative to the threaded rod 200. Since the diameter of the internal thread of the lower top plate 320 gradually increases from top to bottom along the axial direction, only the internal thread at the top of the lower top plate 320 is fully matched with the corresponding external thread 210 of the threaded rod 200. Therefore, when the lower top plate 320 moves downward relative to the threaded rod 200, it can scrape the debris on the surface of the external thread 210 corresponding to the outer periphery of the threaded rod 200, and the scraped debris is discharged through the gap between the internal thread of the lower top plate 320 with a gradually increasing diameter and the external thread 210 of the threaded rod 200. At the same time, the cavity 240 on the inner periphery of the threaded rod 200 is spirally connected to the connecting thread 280 on the outer periphery of the fixing rod 270. After the lower top plate 320 is cleaned, as shown in FIG. Fig.10 As shown, the internal thread of the lower top plate 320 moves to below the external thread 210 corresponding to the outer periphery of the threaded rod 200, where there is a smooth portion 220, and the lower top plate 320 is out of contact with the lower end surface of the nut 400 to be tested.

[0069] The threaded rod 200 is fully matched with the corresponding external thread 210 of the nut 400 to be tested, that is, the internal threads of the nut 400 to be tested are all connected to the corresponding external threads 210 of the threaded rod 200. At this time, the multiple cavities 240 inside the threaded rod 200 also happen to be fully matched with the multiple groups of connecting threads 280 on the periphery of the fixed rod 270, and the installation is completed.

[0070] Start the experiment:

[0071] After setting the tension, the tensile testing machine 130 pulls the upper tooling 110 and the lower tooling 120 away from each other, thereby pulling the fixed rod 270 and the nut 400 to be tested away from each other, the fixed rod 270 is connected to the threaded rod 200, the threaded rod 200 is connected to the nut 400 to be tested, the tension gradually increases, and maintains for a period of time after reaching the set tension, and then gradually decreases after the time is up. The tensile testing machine 130 pushes the upper tooling 110 and the lower tooling 120 closer to each other, thereby facilitating the removal of the fixed rod 270, the threaded rod 200 and the nut 400 to be tested, and detects the state of the internal thread of the nut 400 to be tested. If there is no obvious change in the internal thread of the nut 400 to be tested, it means it is qualified, and if there is an obvious change, it means it is unqualified.

[0072] If the nut 400 to be tested is unqualified and difficult to remove, liquid nitrogen is introduced into the inlet 251 of the threaded rod 200. The liquid nitrogen rapidly cools the side wall of the threaded rod 200 through the spiral channel 250, making the overall size of the threaded rod 200 smaller, thereby reducing the difficulty of removing the nut 400 to be tested.

[0073] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A load holding test equipment for nuts, characterized in that: include: A frame, wherein an upper tooling and a lower tooling are provided on the frame, and a threaded rod and a nut to be tested are detachably mounted on the upper tooling and the lower tooling, respectively, and the upper tooling and the lower tooling are separated from each other to apply tension to the threaded rod and the nut to be tested; The outer circumference of the threaded rod is provided with an external thread along the axial direction, and the lower part of the external thread is a smooth part; A fixture seat, the fixture seat comprises an upper top plate and a lower top plate which can move axially relative to each other, the upper top plate and the lower top plate wrap the nut to be tested to connect the lower fixture, the upper top plate is slidably connected to the threaded rod, the lower top plate has an internal thread, the diameter of the internal thread gradually increases from top to bottom along the axial direction of the threaded rod, and the top diameter of the internal thread is the same as the internal thread diameter of the nut to be tested, and a gap is generated between the external thread of the threaded rod and the internal thread of the lower top plate; When the nut to be tested is not connected to the threaded rod, the upper top plate and the lower top plate respectively abut against the upper and lower ends of the nut to be tested; During the process of connecting the nut to be tested to the threaded rod, the lower top plate firstly passes through the external thread and then separates from the lower end surface of the nut to be tested and is located at the smooth part, and the nut to be tested is then screwed to the threaded rod; When the nut to be tested is installed on the threaded rod, the internal thread on the lower top plate can scrape the debris remaining on the surface of the external thread of the threaded rod, and the debris is discharged through the gap between the external thread of the threaded rod and the internal thread of the lower top plate.

2. The load holding test equipment for nuts according to claim 1, characterized in that: The outer circumference of the threaded rod is axially provided with a plurality of sections of external threads, and the outer circumference diameter of the threaded rod where each section of external threads is located gradually increases from top to bottom along the axial direction, and the smooth portion is located between adjacent external threads.

3. The load holding test equipment for nuts according to claim 1, characterized in that: The threaded rod is hollow inside and is spirally connected with a fixing rod, and the fixing rod can connect the threaded rod to the upper tooling.

4. The load holding test equipment for nuts according to claim 3, characterized in that: The outer circumference of the fixing rod is provided with multiple groups of connecting threads, and the diameter of the fixing rod where each group of connecting threads is located gradually decreases from top to bottom along the axial direction. The rotation direction of each group of connecting threads is the same as the rotation direction of the external threads on the outer circumference of the threaded rod. The interior of the threaded rod is divided into multiple cavities with gradually decreasing diameters from top to bottom along the axial direction, and the multiple cavities are threadedly matched with the multiple groups of connecting threads.

5. The load holding test equipment for nuts according to claim 1, characterized in that: A first hexagonal plate frame and a second hexagonal plate frame are fixedly arranged on the end surfaces of the upper top plate and the lower top plate that are close to each other, respectively. The inner periphery of the first hexagonal plate is in vertical sliding contact with the outer periphery of the second hexagonal plate frame, and the inner periphery of the second hexagonal plate is in vertical sliding contact with the outer periphery of the nut to be tested.

6. The load holding test equipment for nuts according to claim 1, characterized in that: A spiral channel is provided on the side wall of the threaded rod, an inlet and an outlet of the spiral channel are both located near the bottom of the threaded rod, and the spiral channel can be filled with liquid nitrogen.

7. The load holding test equipment for nuts according to claim 1, characterized in that: A hexagonal prism is fixedly connected to the bottom of the threaded rod, and the axis of the hexagonal prism coincides with the axis of the threaded rod.

8. The load holding test equipment for nuts according to claim 1, characterized in that: A tensile machine is arranged on the frame, and the tensile machine is connected to the upper tooling and the lower tooling.

9. The load holding test equipment for nuts according to claim 8, characterized in that: The tensile testing machine is provided with a control module, and the control module can regulate the tensile force of the tensile testing machine on the upper tooling and the lower tooling.

10. The load holding test equipment for nuts according to claim 1, characterized in that: The upper tooling and the lower tooling are both provided with mounting grooves, and the mounting groove of the lower tooling is longer than that of the upper tooling.

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