Self-locking anti-loosening universal hydraulic nut

Abstract

The self-locking anti-loosening universal hydraulic nut comprises a hydraulic cylinder, a piston and a locking nut, the hydraulic cylinder is connected with an external pump station, the piston is located in an oil cavity of the hydraulic cylinder and slidably connected with the hydraulic cylinder, the piston is connected with a bolt through an internal thread of the piston, and the piston is connected with the locking nut through an external thread of the piston. External threads of the piston are sawtooth threads, a self-locking bolt is arranged on the piston, a base is arranged below the hydraulic cylinder, the upper end face of the base is matched with the lower end face of the hydraulic cylinder, the hydraulic cylinder is movably arranged on the base, and the diameter of a through hole in the base is larger than that of the bolt. According to the hydraulic nut, the piston above the notch can be pressed downwards through the self-locking bolt, the locking precision is improved, looseness is prevented, the service life is prolonged, the screw hole is formed in the perpendicular bisector of the notch, the piston is stressed in a balanced mode, meanwhile, the hydraulic cylinder can move on the base, it is ensured that the bolt is stressed evenly and locked reliably, and the thermal cycle test is not influenced. And it is ensured that the hydraulic nut can be used in nuclear power engineering.

Description

Technical Field

[0001] The invention relates to the field of hydraulic nuts, in particular to a self-locking and anti-loosening universal hydraulic nut. Background Art

[0002] Hydraulic nuts are used for bolts that need to be frequently disassembled and assembled; pre-tightening of oversized bolts; locking of large workpieces, etc. For example: nuclear power projects. The principle is to use ultra-high pressure oil to generate a thrust on the shaft and a tension on the sleeve, so that the shaft and sleeve are evenly connected.

[0003] Due to the compact working conditions and limited space of nuclear power projects, if mechanical nuts are used, it will be difficult to pre-tighten them because the nuts need a large space to be removed and installed, so hydraulic nuts are more suitable. Nuclear power projects work in high temperature environments and generate vibrations during work, so the nuts used for connection are prone to loosening. Based on the particularity of nuclear power projects, radiation often exists. Therefore, nuclear power projects cannot be frequently overhauled, which will affect the health of the staff. Therefore, hydraulic nuts are required to have good thermal stability and good sealing to ensure that the hydraulic nuts can work for 50 years.

[0004] The hydraulic nut is mainly composed of three parts, including the hydraulic cylinder, the piston, and the locking nut. The piston is located in the hydraulic cylinder and is slidably connected to the hydraulic cylinder. The piston is provided with internal threads and external threads. It is connected to the bolt through the internal threads and connected to the locking nut through the external threads. The operation steps of the hydraulic nut are as follows: Step 1: Use ultra-high pressure oil to push the piston in the hydraulic cylinder to directly apply external force to the bolt, so that the bolt to which the force is applied is stretched in its elastic deformation zone; Step 2: After the bolt is stretched, tighten the locking nut so that the bolt will be locked in the stretched position by the locking nut. Then the hydraulic cylinder will be depressurized and the hydraulic oil will flow back to the pump station.

[0005] During the actual use of the hydraulic nut, there is a certain gap between the threaded connection parts of the locking nut and the piston.

[0006] In the above step 1, the bolt will be stretched to a length that just meets the preload force. When the hydraulic cylinder is depressurized, the stretched bolt will retract due to the negative pressure state of the hydraulic cylinder and the gap between the locking nut and the piston. This causes the actual preload force to be less than the preset preload force, reduces the locking accuracy, and makes the locking unreliable.

[0007] At the same time, the hydraulic nut will be placed on the plane of the fastener to be fastened during use. The bottom surface of the hydraulic nut is parallel to the plane of the fastener, and the bolt hole in the hydraulic nut is perpendicular to the plane. However, the bolt used for connection cannot reach an absolutely perpendicular state to the plane. In actual use, there may be uneven locking force between the hydraulic nut and the bolt, which not only affects the locking effect, but may also damage the threads on the hydraulic nut and the bolt. Summary of the invention

[0008] The purpose of the present invention is to construct a self-locking and anti-loosening universal hydraulic nut based on the existing hydraulic nut and the need to improve the locking accuracy of the hydraulic nut assembly bolts and to make the hydraulic nut and the bolts evenly stressed after being locked.

[0009] A self-locking and anti-loosening universal hydraulic nut, comprising a hydraulic cylinder, a piston and a locking nut, wherein the oil chamber of the hydraulic cylinder is connected to an external pump station through a flow channel, the piston is located in the oil chamber of the hydraulic cylinder and is slidably connected to the hydraulic cylinder, the piston is an annular structure and is provided with an internal thread and an external thread, the piston is connected to a bolt through an internal thread, and the piston is connected to a locking nut through an external thread, characterized in that a notch is provided at a position slightly above the piston, the notch is arched, the midpoint of the notch passes through the midpoint of the cross section of the piston at that location, a screw hole is also provided on the piston, the screw hole is vertically arranged and passes through the notch, the screw hole is arranged on the midpoint of the notch, and a self-locking bolt is arranged in the screw hole; The self-locking bolt presses down the piston above the notch, causing the outer thread of the piston at the pressed position to deform, thereby reducing the gap between the piston and the locking nut, reducing the retraction of the piston when the hydraulic cylinder is depressurized, thereby improving the locking accuracy, and further reducing the loosening of the hydraulic nut during use, thereby increasing the service life of the hydraulic nut.

[0010] The screw hole is arranged on the midline of the notch, so that the part of the piston used for self-locking is subjected to balanced force on both sides of the midline.

[0011] A base is provided below the hydraulic cylinder, the upper end surface of the base is set as an inwardly concave spherical surface, the lower end surface of the hydraulic cylinder is set as an outwardly convex spherical surface, the upper end surface of the base and the lower end surface of the hydraulic cylinder cooperate with each other, and the hydraulic cylinder is movably arranged on the base; There is an eccentric load of ±1° between the hydraulic cylinder and the base to ensure that the compressive load is perpendicular to the working axis.

[0012] The hydraulic cylinder and the piston can move on the base in accordance with the angle of the bolt, so that the hydraulic nut and the axis of the bolt coincide with each other, ensuring that the bolt is evenly stressed.

[0013] The base is provided with a through hole, and the diameter of the through hole is larger than the diameter of the bolt.

[0014] The thread used to connect the locking nut and the piston is a sawtooth thread. When the sawtooth thread rotates, the sawtooth shape can generate friction with the surface of the mating part, thereby increasing the firmness and sealing of the thread. In addition, the sawtooth thread can prevent loosening or falling off, thereby increasing the service life and stability of the thread.

[0015] Relatively commonly, pipe threads are often used for connection in hydraulic nuts. The threads of pipe threads are more easily deformed than those of serrated threads, and the gap between the internal and external threads after meshing is also larger. Therefore, when the hydraulic nut is depressurized, the use of serrated threads has a better anti-retreat effect and a good pre-tightening effect.

[0016] Furthermore, the bow shape includes a chord and an arc, the midpoint a of the chord and the midpoint b of the arc are taken as the straight line x connecting the two points a and b, the wall thickness of one side of the piston is taken as h, and the radius of the cross section of the piston is taken as r, h<r<x<2r-h.

[0017] The piston used in the self-locking part will not have a poor anti-loosening effect due to a too small locking area, nor will it cause the piston to break due to an overly large notch.

[0018] Furthermore, the notch is arranged horizontally.

[0019] Furthermore, the rotation center line of the self-locking bolt is parallel to the rotation center line of the piston, and the rotation center line of the self-locking bolt is perpendicular to the horizontal plane of the notch.

[0020] Furthermore, the hydraulic cylinder is provided with an oil chamber and a linkage chamber, the oil chamber is communicated with the linkage chamber, the oil chamber is located above the linkage chamber, and the diameter of the oil chamber is larger than the diameter of the linkage chamber.

[0021] Further, the piston comprises an upper part and a lower part, the diameter of the upper part is larger than the diameter of the lower part, a sliding member is provided on the outer side of the upper part of the piston, the sliding member is slidably connected with the inner wall of the oil chamber, the external thread of the piston is provided on the outer side of the upper part of the piston, the external thread of the piston is located above the sliding member, and the lower part of the piston is slidably connected with the linkage chamber, The middle part of the piston is provided with a connecting hole which penetrates from top to bottom, the internal thread is arranged on the hole wall of the connecting hole, and the diameter of the connecting hole is equal to the diameter of the bolt. The piston is provided with a groove, and the groove is communicated with the flow channel.

[0022] Furthermore, a sealing member is provided below the sliding member, and the sealing member is a V-shaped spring energy storage ring. Compared with the common O-shaped sealing ring, the V-shaped spring energy storage ring has a better sealing effect and a longer service life, which can guarantee a service life of 50 years.

[0023] Furthermore, the locking nut is provided with a plurality of connection holes for connecting a twisting tool.

[0024] Hydraulic nuts are often used to lock large workpieces, such as nuclear power projects. Since nuclear power projects have compact working conditions and limited space, if mechanical nuts are used, the equipment needs to be disassembled for maintenance, which is difficult. Therefore, hydraulic nuts are more suitable. Only a hydraulic pump needs to be connected to detect whether the nuts are loose. However, nuclear power projects have higher performance requirements for hydraulic nuts, so they need to be tested.

[0025] The above hydraulic nut is now subjected to a thermal cycle test, and the specific scheme is as follows: Step 1: Apply oil pressure to the hydraulic nut step by step through the hydraulic pump, and record the axial force value obtained in each test when the oil pressure increases from 0 to 100 MPa with an increase of 10 MPa. Reversely calculate the oil pressure value through the conversion formula between the axial force and the oil pressure value, and simultaneously check whether there is oil leakage at the connection part of the hydraulic hose and whether the hydraulic nut exceeds the stroke requirement; Step 2: After reaching the maximum pressure state of 100 MPa, self-lock the hydraulic nut and tighten the self-locking bolt, respectively record the axial force values ​​before and after the hydraulic oil pump is removed in the stopped state, and reversely calculate the oil pressure value through the conversion formula of the axial force and the oil pressure value; Step 3, put the hydraulic nut and the supporting test equipment into an oven (hot air circulation oven), use the oven to heat the hydraulic nut, make the hydraulic nut temperature rise at a rate of 2℃ / min, when the temperature of the hydraulic nut reaches 100℃, keep it warm for 1 hour, measure the axial force, and reversely calculate the oil pressure value through the conversion formula of axial force and oil pressure value, wait for the temperature to cool to room temperature, keep it for 2 hours, measure the axial force, and reversely calculate the oil pressure value through the conversion formula of axial force and oil pressure value, repeat the heating and cooling process for multiple cycles; Step 4: Analyze the test data, check the thermal stability of the hydraulic nut, and ensure that the mechanical properties of the hydraulic nut are stable in a complex temperature environment; The conversion formula between axial force and oil pressure is: Oil pressure value (MPa) = [axial force (kN) / 9.8 + 2] / 0.04 × 0.098.

[0026] Furthermore, the hydraulic nut is made of non-magnetic material, which can ensure the mechanical properties of the hydraulic nut.

[0027] The beneficial effects of the present invention are as follows: the self-locking and anti-loosening universal hydraulic nut disclosed in the present application can press down the piston above the notch through the self-locking bolt, so that the outer thread of the piston at the pressing position is deformed, and the outer thread of the piston adopts a sawtooth thread, thereby reducing the gap between the piston and the locking nut, reducing the retraction of the piston when the hydraulic cylinder is depressurized, thereby improving the locking accuracy, preventing the hydraulic nut from loosening during use, and increasing the service life of the hydraulic nut, and the screw hole is arranged on the mid-vertical line of the notch, so that the force of the piston at the pressing position is balanced, and at the same time, the hydraulic cylinder and the piston can move on the base in accordance with the angle of the bolt, so that the axis of the hydraulic nut coincides with the bolt, ensuring that the bolt is evenly stressed, further ensuring reliable locking, and preventing the thread damage of the bolt and the hydraulic nut. The thermal cycle test of the hydraulic nut can directly understand the mechanical properties of the hydraulic nut and ensure that the hydraulic nut can be used in nuclear power projects.

[0028] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. Figure 1 It is a schematic diagram of the overall structure of a specific example of the hydraulic nut of the present invention; Figure 2 yes Figure 1 A schematic cross-sectional structure diagram of ; Figure 3 It is a structural schematic diagram of a hydraulic cylinder in a specific example of a hydraulic nut of the present invention; Figure 4 It is a structural schematic diagram of a piston in a specific example of a hydraulic nut of the present invention; Figure 5 yes Figure 2 A magnified view of the structure at center; Figure 6 It is a structural schematic diagram of a locking nut in a specific example of a hydraulic nut of the present invention; Figure 7 It is a schematic diagram of the cross-sectional structure of a base in a specific example of the hydraulic nut of the present invention; Figure 8 is a schematic diagram of the cross-sectional structure of a piston at a notch in a specific example of a hydraulic nut of the present invention; Fig. 9 is a test data table of a specific example of the hydraulic nut of the present invention; Fig.10 is a test data table of a specific example of the hydraulic nut of the present invention; In the figure: 101, base; 102, hydraulic cylinder; 103, interface; 104, piston; 105, locking nut; 106, connecting hole; 107, through hole; 109, linkage chamber; 110, flow channel; 111, oil chamber; 112, self-locking bolt; 113, screw hole; 114, notch; 115, sliding part; 117, connecting hole; 120, annular groove; 121, V-shaped spring energy storage ring. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. 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.

[0031] A self-locking and anti-loosening universal hydraulic nut of the present invention is further described in conjunction with the accompanying drawings.

[0032] like Figure 1 and Figure 2 As shown, the hydraulic nut described in this embodiment is made of non-magnetic material, and the hydraulic nut includes a base 101, a hydraulic cylinder 102, a piston 104 and a locking nut 105. The hydraulic cylinder 102 is arranged above the base 101, and a hydraulic oil interface 103 is connected to the hydraulic cylinder 102. The hydraulic cylinder 102 is connected to an external pump station through the interface 103. The piston 104 is arranged in the hydraulic cylinder 102, and the piston 104 is slidably connected to the hydraulic cylinder 102. The piston 104 is connected to the locking nut 105 through a thread, and a self-locking bolt 112 is provided on the piston 104.

[0033] like Figure 2 and Figure 3 As shown, the hydraulic cylinder 102 is provided with an oil chamber 111 and a linkage chamber 109, the oil chamber 111 and the linkage chamber 109 are connected, the diameter of the oil chamber 111 is larger than the diameter of the linkage chamber 109, the oil chamber 111 is located above the linkage chamber 109, a flow channel 110 is provided in the hydraulic cylinder 102, the flow channel 110 includes a horizontal section and a vertical section, the horizontal section of the flow channel 110 is connected to the interface 103, the vertical section of the flow channel 110 is connected to the oil chamber 111, and the horizontal section of the flow channel 110 is connected to the vertical section of the flow channel 110. The lower end surface of the hydraulic cylinder 102 is a spherical surface convex downward.

[0034] like Figure 2 and Figure 7As shown, the upper end surface of the base 101 is set to a downwardly concave spherical surface, the lower end surface of the hydraulic cylinder 102 corresponds to and cooperates with the shape of the upper end surface of the base 101, the hydraulic cylinder 102 is movably arranged on the base 101, and a through hole 107 is provided in the middle of the base 101 that passes through from top to bottom. The diameter of the through hole 107 is larger than the diameter of the bolt, and the through hole 107 is connected to the linkage chamber 109.

[0035] like Figure 2 and Figure 4 As shown, the piston 104 includes an upper part and a lower part, the diameter of the upper part is larger than the diameter of the lower part, and a connecting hole 106 is provided in the middle of the piston 104, which passes through the upper and lower parts, and an internal thread is provided on the hole wall of the connecting hole 106, which is used to connect with a bolt, and the diameter of the connecting hole 106 is equal to the diameter of the bolt. An external thread is provided on the outer side of the upper part of the piston 104, and the external thread is used to connect with a locking nut 105.

[0036] The thread used to connect the locking nut 105 and the piston 104 is a sawtooth thread, and the teeth of the sawtooth thread include a first thread surface and a second thread surface. The first thread surface forms an angle of 3° with the rotation axis (the rotation axis is the straight line where the rotation axis center line of the locking nut is located), and the second thread surface forms an angle of 30° with the rotation axis.

[0037] The lower portion of the piston 104 is slidably connected to the linkage chamber 109 .

[0038] A notch 114 is provided at an upper position of the piston 104 , and the notch 114 is arranged horizontally. The piston 104 is also provided with a screw hole 113 , and the screw hole 113 is arranged vertically and passes through the notch 114 . The self-locking bolt 112 is arranged at the screw hole 113 .

[0039] like Figure 2 and Figure 5 As shown, a sliding member 115 is provided on the outside of the piston 104, and the sliding member 115 is slidably connected to the inner wall of the oil chamber 111. The external thread arranged on the piston 104 is located above the sliding member 115, and a V-shaped spring energy storage ring 121 is provided below the sliding member 115.

[0040] An annular groove 120 is formed on the lower end surface of the upper portion of the piston 104 , and the annular groove 120 is communicated with the flow channel 110 .

[0041] like Figure 2 and Figure 8 As shown, the slot 114 is in the shape of an arch, and the arch includes a chord and an arc, with the midpoint a of the chord and the midpoint b of the arc, and the straight line obtained by connecting the two points a and b is x, and the straight line where the straight line x is located is the perpendicular bisector of the arch, that is, the straight line where the straight line x is located is the perpendicular bisector of the slot 114, and the perpendicular bisector passes through the midpoint O of the cross section of the piston 104, and the above-mentioned screw hole 113 is arranged on the perpendicular bisector.

[0042] Assume that the thickness of the single side wall of the piston 104 is h, the radius of the cross section of the piston 104 is r, and h<r<x<2r-h.

[0043] like Figure 6 As shown, the locking nut 105 is provided with six connection holes 117 for connecting a screwing tool.

[0044] When using hydraulic nuts to install bolts, a. Connect the hydraulic nut to the bolt through the internal thread on the piston 104, and use the ultra-high pressure oil to push the piston 104 in the hydraulic cylinder 102, so that the bolt to which the force is applied is stretched in its elastic deformation zone; b. Tighten the locking nut 105 to lock the bolt in the stretched position; c. The self-locking bolt 112 is turned to press the piston 104 above the notch 114 downward, and the external thread at the downward pressure position is displaced and deformed, so that the gap between the external thread and the internal thread of the locking nut 105 is reduced. After the hydraulic cylinder 102 is depressurized, the retraction of the piston 104 is also reduced.

[0045] If the axis of the installed bolt is not perpendicular to the lower end surface of the hydraulic nut, the hydraulic cylinder 102 will move on the base 101 so that the axis of the piston 104 coincides with the axis of the bolt.

[0046] A thermal cycle test is now performed on the hydraulic nut in the embodiment.

[0047] The conversion formula between axial force and oil pressure is: Oil pressure value (MPa) = [axial force (kN) / 9.8 + 2] / 0.04 × 0.098.

[0048] The measured axial force is automatically converted into oil pressure value through the above formula algorithm. Fig. 9 and Fig.10 In order to facilitate data comparison, the converted oil pressure value is marked as Axial force.

[0049] (1) Apply oil pressure to the hydraulic nut step by step through the hydraulic pump, and record the axial force value obtained in each test when the oil pressure increases from 0 to 100 MPa with an increase of 10 MPa. When the oil pressure is 0 MPa, the axial force value is 2.9 MPa; When the oil pressure is 10 MPa, the axial force value is 10.4 MPa; When the oil pressure is 20 MPa, the axial force value is 19.7 MPa; When the oil pressure is 30 MPa, the axial force value is 29.4 MPa; When the oil pressure is 40 MPa, the axial force value is 39.1 MPa; When the oil pressure is 50 MPa, the axial force value is 48.3 MPa; When the oil pressure is 60 MPa, the axial force value is 58.5 MPa; When the oil pressure is 70 MPa, the axial force value is 67.4 MPa; When the oil pressure is 80 MPa, the axial force value is 76.6 MPa; When the oil pressure is 90 MPa, the axial force value is 86.4 MPa; When the oil pressure is 100 MPa, the axial force value is 96.6 MPa.

[0050] (2) When the oil pressure is at the highest pressure state of 100 MPa, the self-locking hydraulic nut is tightened and the self-locking bolt 112 is tightened. The axial force value before the hydraulic oil pump is removed is measured to be 97.2 MPa, and the axial force value after the hydraulic oil pump is removed is 63.5 MPa.

[0051] (3) Place the hydraulic nut and the supporting test equipment into the oven. Test 1: The axial force value before heating was measured to be 56.3MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 58.7MPa. The oil pressure value was calculated by reverse calculation. When the temperature cooled to room temperature and maintained for 2 hours, the axial force value after cooling was measured to be 55.2MPa.

[0052] Test 2: The axial force value before heating was measured to be 55.7MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 58.3MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 55.6MPa.

[0053] Test 3: The axial force value before heating was measured to be 56.0MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 58.1MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 55.7MPa.

[0054] Test 4: The axial force value before heating was measured to be 55.7MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 58.3MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 55.7MPa.

[0055] Test 5: The axial force value before heating was measured to be 55.8MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 57.6MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 55.4MPa.

[0056] Test 6: The axial force value before heating was measured to be 55.6MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 57.4MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 55.4MPa.

[0057] Test 7: The axial force value before heating was measured to be 55.5MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 57.3MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 55.1MPa.

[0058] Test 8: The axial force value before heating was measured to be 55.2MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 57.3MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 55.0MPa.

[0059] Test 9: The axial force value before heating was measured to be 55.2MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 57.3MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.9MPa.

[0060] Test 10: The axial force value before heating was measured to be 55.0MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 57.2MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.8MPa.

[0061] Test 11: The axial force value before heating was measured to be 55.0MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 57.0MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.7MPa.

[0062] Test 12: The axial force value before heating was measured to be 54.9MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 57.0MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.7MPa.

[0063] Test 13: The axial force value before heating was measured to be 54.9MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.8MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.7MPa.

[0064] Test 14: The axial force value before heating was measured to be 54.8MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 57.0MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.7MPa.

[0065] Test 15: The axial force value before heating was measured to be 54.8MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.9MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.7MPa.

[0066] Test 16: The axial force value before heating was measured to be 54.7MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.4MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.6MPa.

[0067] Test 17: The axial force value before heating was measured to be 54.7MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.8MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.6MPa.

[0068] Test 18: The axial force value before heating was measured to be 54.6MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.9MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.4MPa.

[0069] Test 19: The axial force value before heating was measured to be 54.6MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.7MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.4MPa.

[0070] Test 20: The axial force value before heating was measured to be 54.5MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.6MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.3MPa.

[0071] Test 21: The axial force value before heating was measured to be 54.5MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.4MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.4MPa.

[0072] Test 22: The axial force value before heating was measured to be 54.4MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.3MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.1MPa.

[0073] Test 23: The axial force value before heating was measured to be 54.3MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.2MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.1MPa.

[0074] Test 24: The axial force value before heating was measured to be 54.2MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.6MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.0MPa.

[0075] Test 25: The axial force value before heating was measured to be 54.2MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.4MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.1MPa.

[0076] Test 26: The axial force value before heating was measured to be 54.2MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.7MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.0MPa.

[0077] Test 27: The axial force value before heating was measured to be 54.1MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.5MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.0MPa.

[0078] Test 28: The axial force value before heating was measured to be 54.2MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.5MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.0MPa.

[0079] Test 29: The axial force value before heating was measured to be 54.2MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.6MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 54.0MPa.

[0080] Test 30: The axial force value before heating was measured to be 54.1MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.5MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.9MPa.

[0081] Test 31: The axial force value before heating was measured to be 54.1MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.5MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.9MPa.

[0082] Test 32: The axial force value before heating was measured to be 54.0MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.4MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.9MPa.

[0083] Test 33: The axial force value before heating was measured to be 54.0MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.5MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0084] Test 34: The axial force value before heating was measured to be 54.1MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.5MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.9MPa.

[0085] Test 35: The axial force value before heating was measured to be 54.0MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.4MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0086] Test 36: The axial force value before heating was measured to be 54.0MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.5MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0087] Test 37: The axial force value before heating was measured to be 54.0MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.5MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0088] Test 38: The axial force value before heating was measured to be 54.0MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.3MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0089] Test 39: The axial force value before heating was measured to be 53.9MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.4MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0090] Test 40: The axial force value before heating was measured to be 54.0MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.4MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0091] Test 41: The axial force value before heating was measured to be 53.9MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.3MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.7MPa.

[0092] Test 42: The axial force value before heating was measured to be 53.9MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.4MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0093] Test 43: The axial force value before heating was measured to be 54.0MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 55.7MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0094] Test 44: The axial force value before heating was measured to be 53.8MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.0MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0095] Test 45: The axial force value before heating was measured to be 53.9 MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 55.8 MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8 MPa.

[0096] Test 46: The axial force value before heating was measured to be 53.8MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 55.8MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.7MPa.

[0097] Test 47: The axial force value before heating was measured to be 53.9MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.0MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0098] Test 48: The axial force value before heating was measured to be 53.8MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 55.8MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.8MPa.

[0099] Test 49: The axial force value before heating was measured to be 53.8MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 55.4MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.7MPa.

[0100] Test 50: The axial force value before heating was measured to be 53.7MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 55.8MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.6MPa.

[0101] Test 51: The axial force value before heating was measured to be 53.8MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 55.7MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.6MPa.

[0102] Test 52: The axial force value before heating was measured to be 53.7MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 55.9MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.6MPa.

[0103] Test 53: The axial force value before heating was measured to be 53.7MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 55.9MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.5MPa.

[0104] Test 54: The axial force value before heating was measured to be 53.7MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 55.9MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.5MPa.

[0105] Test 55: The axial force value before heating was measured to be 53.7MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 55.9MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.5MPa.

[0106] Test 56: The axial force value before heating was measured to be 53.6MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.0MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.5MPa.

[0107] Test 57: The axial force value before heating was measured to be 53.7MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.1MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.5MPa.

[0108] Test 58: The axial force value before heating was measured to be 53.7MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.1MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.6MPa.

[0109] Test 59: The axial force value before heating was measured to be 53.6MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.0MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.5MPa.

[0110] Test 60: The axial force value before heating was measured to be 53.6MPa. The hydraulic nut was then heated in an oven. When the temperature of the hydraulic nut reached 100°C, it was kept warm for 1 hour. The axial force value after heating was measured to be 56.1MPa. After the temperature was cooled to room temperature and kept for 2 hours, the axial force value after cooling was measured to be 53.5MPa.

[0111] (4) If Fig. 9 and Fig.10As shown, the axial force value before heating measured in the initial test 1 is 56.3MPa as the standard value Z. In tests 1 to 60, the maximum axial force value MAX measured is 58.7MPa, and the minimum axial force value MIN measured is 53.5MPa. The absolute value of the difference between the maximum axial force value MAX or the minimum axial force value MIN and the standard value Z is taken, and the percentage of the absolute value in the standard value Z is taken. The final value is the change rate S of the axial force value. The formula is as follows: or ; The change rate S of the maximum axial force value MAX compared to the standard value Z MAX =4.26%, the change rate S of the minimum axial force value MIN compared to the standard value Z MIN =4.97%, S MAX and S MIN The hydraulic nut has good thermal stability and its mechanical properties are stable in a complex temperature environment.

[0112] The axial force values ​​in (1) to (4) above are the oil pressure values ​​obtained by converting the measured axial force.

[0113] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A self-locking and anti-loosening universal hydraulic nut, comprising a hydraulic cylinder, a piston and a locking nut, wherein the oil chamber of the hydraulic cylinder is connected to an external pump station through a flow channel, the piston is located in the oil chamber of the hydraulic cylinder and is slidably connected to the hydraulic cylinder, the piston is an annular structure and is provided with an internal thread and an external thread, the piston is connected to a bolt through an internal thread, and the piston is connected to a locking nut through an external thread, characterized in that: A notch is provided at the upper part of the piston, the notch is in an arcuate shape, the perpendicular midline of the notch passes through the midpoint of the cross section of the piston at that position, a screw hole is also provided on the piston, the screw hole is vertically arranged and passes through the notch, the screw hole is arranged on the perpendicular midline of the notch, and a self-locking bolt is arranged in the screw hole, A base is provided below the hydraulic cylinder, the upper end surface of the base is set as a concave spherical surface, the lower end surface of the hydraulic cylinder is set as a convex spherical surface, the upper end surface of the base and the lower end surface of the hydraulic cylinder cooperate with each other, and the hydraulic cylinder is movably arranged on the base. The base is provided with a through hole, and the diameter of the through hole is larger than the diameter of the bolt; The thread used to connect the locking nut and the piston is a buttress thread.

2. A self-locking and anti-loosening universal hydraulic nut according to claim 1, characterized in that: The bow shape includes a chord and an arc. The midpoint a of the chord and the midpoint b of the arc are taken as the straight line x connecting the two points a and b. The wall thickness of one side of the piston is taken as h, and the radius of the cross section of the piston is taken as r. h<r<x<2r-h.

3. The self-locking and anti-loosening universal hydraulic nut according to claim 1, characterized in that: The notch is arranged horizontally.

4. The self-locking and anti-loosening universal hydraulic nut according to claim 1, characterized in that: The rotation center line of the self-locking bolt is parallel to the rotation center line of the piston, and the rotation center line of the self-locking bolt is perpendicular to the horizontal plane of the notch.

5. The self-locking and anti-loosening universal hydraulic nut according to claim 1, characterized in that: The hydraulic cylinder is provided with an oil chamber and a linkage chamber, the oil chamber is communicated with the linkage chamber, the oil chamber is located above the linkage chamber, and the diameter of the oil chamber is greater than the diameter of the linkage chamber.

6. A self-locking and anti-loosening universal hydraulic nut according to claim 5, characterized in that: The piston comprises an upper part and a lower part, wherein the diameter of the upper part is larger than the diameter of the lower part, a sliding part is arranged on the outer side of the upper part of the piston, and the sliding part is slidably connected with the inner wall of the oil chamber, the outer thread of the piston is arranged on the outer side of the upper part of the piston, the outer thread of the piston is located above the sliding part, and the lower part of the piston is slidably connected with the linkage chamber, The middle part of the piston is provided with a connecting hole which penetrates from top to bottom, the internal thread is arranged on the hole wall of the connecting hole, and the diameter of the connecting hole is equal to the diameter of the bolt. The piston is provided with a groove, and the groove is communicated with the flow channel.

7. A self-locking and anti-loosening universal hydraulic nut according to claim 6, characterized in that: A sealing member is provided below the sliding member, and the sealing member is a V-shaped spring energy storage ring.

8. The self-locking and anti-loosening universal hydraulic nut according to claim 1, characterized in that: The locking nut is provided with a plurality of connection holes for connecting a screwing tool.

9. The self-locking and anti-loosening universal hydraulic nut according to claim 1, characterized in that: The hydraulic nut is made of non-magnetic material.

10. A self-locking and anti-loosening universal hydraulic nut according to any one of claims 1 to 9, characterized in that: The thermal cycle test of hydraulic nuts is carried out as follows: Step 1: Apply oil pressure to the hydraulic nut step by step through the hydraulic pump, and record the axial force value obtained in each test when the oil pressure increases from 0 to 100 MPa with an increase of 10 MPa. Reversely calculate the oil pressure value through the conversion formula between the axial force and the oil pressure value, and simultaneously check whether there is oil leakage at the connection part of the hydraulic hose and whether the hydraulic nut exceeds the stroke requirement; Step 2: After reaching the maximum pressure state of 100 MPa, self-lock the hydraulic nut and tighten the self-locking bolt, respectively record the axial force values ​​before and after the hydraulic oil pump is removed in the stopped state, and reversely calculate the oil pressure value through the conversion formula of the axial force and the oil pressure value; Step 3, put the hydraulic nut and the supporting test equipment into the oven, use the oven to heat the hydraulic nut, make the hydraulic nut temperature rise at a rate of 2 ° C / min, when the temperature of the hydraulic nut reaches 100 ° C, keep it warm for 1 hour, measure the axial force, and reversely calculate the oil pressure value through the conversion formula of the axial force and the oil pressure value, wait for the temperature to cool to room temperature, keep it for 2 hours, measure the axial force, and reversely calculate the oil pressure value through the conversion formula of the axial force and the oil pressure value, and repeat the heating and cooling process for multiple cycles; Step 4: Analyze the test data, check the thermal stability of the hydraulic nut, and ensure that the mechanical properties of the hydraulic nut are stable in a complex temperature environment; The conversion formula between axial force and oil pressure is: Oil pressure value = [axial force / 9.8+2] / 0.04×0.098.

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