Hydraulic lock nut and method of use

Abstract

The present application relates to the technical field of bar continuous rolling mill, and particularly relates to a hydraulic locking nut and a use method. The hydraulic locking nut comprises a pull rod, a pressing block assembly, a screw cap, a force releasing bolt and a piston. One end of the pull rod is provided with a pin hole. The pressing block assembly is coaxially sleeved on the outer side of the pull rod and can slide along the axial direction of the pull rod. The piston is located in the interior of the pressing block assembly and is fixedly sleeved on the outer side of the pull rod. The pull rod is provided with a convex surface. The upper surface of the pull rod is lower than the convex surface. The side surface of the piston is dynamically sealed with the inner wall of the pressing block assembly. The pressing block assembly is dynamically sealed with the pull rod. The sealing performance of the oil cavity of the hydraulic locking nut can be improved. Even if a problem occurs, the screw cap can be smoothly loosened under the condition of complete locking. The pull rod does not need to be damaged by oxygen cutting, so that the production cost is saved, the disassembly efficiency is improved, and the disassembly difficulty is reduced.

Description

Technical Field

[0001] This invention relates to the field of bar continuous rolling mill technology, specifically to a hydraulic locking nut and its usage method. Background Technology

[0002] The short stress line mill is used to produce precision metal bars. The mill core and core base are positioned using locating pins and keys, and secured and connected as a whole by four sets of hydraulic locking nuts. During roll changes and tooling maintenance, the hydraulic nuts are loosened to separate the mill core and core base.

[0003] After the mill core is installed on the core base, four hydraulic locking nuts are placed into the core slots and erected. Then, the cap is manually tightened to eliminate the gap between the pin hole of the tie rod and the pin shaft of the core base. After the cap can no longer be tightened, a manual or electric high-pressure pump is used to pressurize the hydraulic nuts. During this process, the cylinder moves downward to pressurize the core. When the pressure gauge reaches the set value, the pressurization is stopped. The pin shaft deforms slightly and the tie rod is stretched, creating a gap between the cylinder and the cap. At this point, the cap is tightened again to eliminate the gap between the cylinder and the cap. Finally, the high-pressure pump is used to release the oil pressure in the cylinder to 0 MPa and the cylinder oil port is sealed, and the hydraulic nuts are in a fully locked state.

[0004] Because the cylinder and piston seals of the hydraulic locking nut operate in an ultra-high pressure environment, unstable sealing quality or aging failure frequently occurs. In the fully locked state, the powerful force generated by the pull rod acts on the cap through the cylinder. If a sealing problem occurs, the pressure inside the cylinder will never reach the required level when the high-pressure pump pressurizes. The powerful force generated by the pull rod will then continuously act on the cap through the cylinder, making it difficult to loosen the cap and disassemble the mechanism. This necessitates frequent destructive disassembly, increasing production costs and reducing disassembly efficiency. Summary of the Invention

[0005] (I) The problem to be solved by the present invention is that when the hydraulic locking nut is fully locked, the sealing quality is unstable or it fails due to aging, which makes it difficult to loosen the cap and disassemble the mechanism. In this case, it can only be removed by destructive means, which increases production costs and reduces disassembly efficiency.

[0006] (II) Technical Solution

[0007] A hydraulic locking nut, comprising:

[0008] The assembly includes a pull rod, a pressure block assembly, a screw cap, a relief bolt, and a piston; one end of the pull rod is provided with a pin hole.

[0009] The pressure block assembly is coaxially sleeved on the outside of the pull rod and can slide relative to the pull rod along the axial direction. The piston is located inside the pressure block assembly and is fixedly sleeved on the outside of the pull rod. The pull rod has a protruding surface, and the upper surface of the pull rod is lower than the protruding surface. The side of the piston is dynamically sealed to the inner wall of the pressure block assembly, and the pressure block assembly is dynamically sealed to the pull rod.

[0010] The pressure block assembly and the piston cooperate to form an oil cavity located on the side of the piston facing the pin hole and distributed circumferentially around the pull rod. The pressure block assembly has an oil port that is connected to the oil cavity.

[0011] The cap is located on the side of the pressure block assembly away from the pin hole and is threaded with the pull rod. An annular cavity is formed between the inner wall of the cap and the outer side of the pull rod.

[0012] The pressure block assembly extends into the annular cavity from the end face near the cap, and the inner wall of the cap dynamically seals with the side of the pressure block assembly.

[0013] Multiple unloading bolts are evenly screwed onto the cap around the axis of the cap, and one end of each unloading bolt facing the pressure block assembly extends into the annular cavity;

[0014] In the locked state, the unloading bolt is used to push the pressure block assembly toward the pin hole; in the unlocked state, the portion of the unloading bolt that extends into the annular cavity retracts into the cap to provide space for the pressure block assembly to retract.

[0015] According to one embodiment of the present invention, the pressing block assembly includes a cylinder body and a pressing ring, the pressing ring being coaxially disposed with the cylinder body, and the pressing ring being fixed to the end face of the cylinder body facing the screw cap;

[0016] The cylinder body and the side of the pull rod are dynamically sealed, and the inner wall of the cylinder body and the side of the piston are dynamically sealed;

[0017] The oil chamber is formed between the inside of the cylinder and the piston, and the oil port is opened on the cylinder;

[0018] The pressure ring extends into the annular cavity of the cap from the end face facing the cap, and forms a dynamic seal with the inner wall of the cap.

[0019] According to one embodiment of the present invention, the pull rod includes a rod body and a threaded sleeve, the inner wall of the threaded sleeve is provided with an internal thread and the outer surface is provided with an external thread, and the threaded sleeve and the rod body are engaged by the internal thread.

[0020] The threaded sleeve is located on the side of the piston away from the pin hole, and the screw cap is threadedly installed on the threaded sleeve, with one end of the threaded sleeve abutting against the end face of the piston facing the screw cap.

[0021] According to one embodiment of the present invention, the hydraulic locking nut includes a washer, the washer being sleeved on the threaded sleeve and slidable relative to the threaded sleeve along its axial direction, the outer side of the washer dynamically sealing the inner wall of the cap, and the washer being located between the pressure ring and the unloading bolt.

[0022] According to one embodiment of the present invention, at least one inner piston sealing ring is provided between the inner surface of the piston and the side of the pull rod, at least one outer piston sealing ring is provided between the outer surface of the piston and the inner wall of the cylinder, and at least one axial sealing ring is provided between the cylinder and the pull rod.

[0023] According to one embodiment of the present invention, the inner diameter of the pressure ring is larger than the outer diameter of the threaded sleeve, and an annular cavity is formed between the inner surface of the pressure ring and the outer surface of the threaded sleeve. A spring is sleeved in the annular cavity. When the spring is in a compressed state, the two ends of the spring are in contact with the piston and the pressure ring, respectively.

[0024] According to one embodiment of the present invention, a dustproof ring and a guide strip are sequentially provided between the cylinder body and the side of the pull rod along the axial direction of the pull rod, and the axial sealing ring is located between the guide strip and the piston.

[0025] According to one embodiment of the present invention, the cylinder body has a threaded hole on the end face facing the pressure ring, and the pressure ring has a screw hole corresponding to the threaded hole on the end face, and the threaded hole and the screw hole are connected by a screw.

[0026] A method for using a hydraulic locking nut, the method comprising a locking method and a loosening method under depressurized oil chamber conditions;

[0027] The locking method includes the following steps:

[0028] The first step is to install the mill core on the core base, then raise the hydraulic locking nut, apply grease to the relief bolt and screw it into the cap, then screw the cap into the pull rod, and then screw the relief bolt into the annular cavity of the cap.

[0029] The second step is to use a tool to tighten the cap so that the pressure block assembly is firmly pressed onto the movement base;

[0030] Third, use a high-pressure pump to pressurize the oil port. The pressure in the oil chamber gradually increases, and the pressure block assembly is pressed down again under the pressure. A gap is created between the pressure block assembly and the unloading bolt. Then, use a tool to tighten the cap again to eliminate the gap between the pressure block assembly and the unloading bolt.

[0031] The fourth step is to use a high-pressure pump to relieve the pressure inside the oil chamber;

[0032] The release method under the depressurized oil chamber condition includes the following steps:

[0033] First, use a torque wrench or socket to turn the first unloading bolt in the opposite direction by a turns, and then turn the unloading bolt that is symmetrical to the previous unloading bolt about the axis of the cap in the opposite direction, so that the unloading bolt turns by a turns.

[0034] The second step is to loosen the unloading bolt adjacent to the first unloading bolt in the first step by turning the screw cap counterclockwise, so that the unloading bolt rotates a turns. Then, turn the unloading bolt opposite to the first unloading bolt so that the unloading bolt rotates a turns.

[0035] Third, loosen the remaining unloading bolts by turning them counterclockwise, turning each unloading bolt a turns.

[0036] Fourth, repeat steps one through three until all the unloading bolts are completely loosened;

[0037] Fifth step, use a tool to loosen the screw cap.

[0038] According to one embodiment of the present invention, in the third step of the locking method, the pressure applied by the high-pressure pump to the oil port is 45 MPa-50 MPa.

[0039] The beneficial effects of this invention are:

[0040] The present invention provides a hydraulic locking nut, comprising:

[0041] Tie rod, pressure block assembly, screw cap, unloading bolt, and piston; one end of the tie rod is provided with a pin hole;

[0042] The pressure block assembly is coaxially sleeved on the outside of the pull rod and can slide relative to the pull rod along the axial direction. The piston is located inside the pressure block assembly and is fixedly sleeved on the outside of the pull rod. The pull rod has a raised surface, and the upper surface of the pull rod is lower than the raised surface. The side of the piston is dynamically sealed with the inner wall of the pressure block assembly, and the pressure block assembly is dynamically sealed with the pull rod.

[0043] The pressure block assembly and the piston cooperate to form an oil chamber located on the side of the piston facing the pin hole and distributed around the tie rod circumferentially. The pressure block assembly has an oil port that is connected to the oil chamber.

[0044] The cap is located on the side of the pressure block assembly away from the pin hole and is threaded with the pull rod. An annular cavity is formed between the inner wall of the cap and the outer side of the pull rod.

[0045] The end face of the pressure block assembly near the cap extends into the annular cavity, and the inner wall of the cap dynamically seals with the side of the pressure block assembly.

[0046] Multiple stress relief bolts are evenly screwed onto the cap around the axis of the cap, and the end of each stress relief bolt facing the pressure block assembly extends into the annular cavity;

[0047] In the locked state, the unloading bolt is used to push the pressure block assembly toward the pin hole; in the unlocked state, the part of the unloading bolt that extends into the ring cavity retracts into the cap to reserve space for the pressure block assembly to retract.

[0048] If the seal within the oil chamber malfunctions, and the pressure inside the oil chamber cannot be increased using a high-pressure pump, multiple relief bolts can be loosened. The lower ends of the relief bolts retract into the inside of the cap, meaning the lower ends of the relief bolts are higher than the inner end face. This creates a gap between the upper surface of the pressure block assembly and the inner end face of the cap. The upward reaction force on the pressure block assembly drives it upward, gradually narrowing the gap between the upper surface of the pressure block assembly and the inner end face of the cap. Since the length of the pulled rod after stretching is typically only a few tenths of a millimeter, and the length of the relief bolt protruding from the inner end face is greater than the length of the stretched rod, the pressure block assembly will not touch the inner end face of the cap during the rod's recovery process. Thus, the cap itself is not under stress, and it can be easily unscrewed. In short, the relief bolts create space for the pull rod to recover its deformation, ensuring that the pull rod does not contact the cap during this process.

[0049] Even if the sealing performance of the hydraulic locking nut's oil chamber fails, the cap can still be easily loosened when fully locked. This avoids the problem of the cap being unable to be loosened, which would prevent the movement from being disassembled and necessitate destructive oxygen cutting of the pull rod. It can also be used as an emergency locking mechanism in case the pressure block assembly seal fails. This saves production costs, improves disassembly efficiency, and reduces disassembly difficulty. Attached Figure Description

[0050] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0051] Figure 1 This is a schematic diagram of the structure provided in Embodiment 1 of the present invention;

[0052] Figure 2 This is a cross-sectional view provided in Embodiment 1 of the present invention;

[0053] Figure 3 This is a first-view view of the pull rod, pressure block assembly, screw cap, and piston provided in Embodiment 1 of the present invention;

[0054] Figure 4 This is a second-view view of the pull rod, pressure block assembly, screw cap, and piston provided in Embodiment 1 of the present invention;

[0055] Figure 5 This is a top view of the screw cap provided in Embodiment 1 of the present invention;

[0056] Figure 6 This is a structural diagram of the piston provided in Embodiment 1 of the present invention;

[0057] Figure 7 This is a structural diagram of the pressure ring provided in Embodiment 1 of the present invention.

[0058] Icons: 1. Tie rod; 101. Pin hole; 2. Cylinder block; 201. Oil port; 3. Piston; 301. Outer groove; 302. Inner groove; 4. Pressure ring; 401. Screw hole; 402. Mounting groove; 5. Screw sleeve; 6. Spring; 7. Washer; 8. Cap; 801. Inner end face; 9. Unloading bolt; 10. Dust seal; 11. Guide band; 12. Axial seal; 13. Piston outer seal; 14. Piston inner seal; 15. Screw; 16. O-ring; 17. Oil chamber. Detailed Implementation

[0059] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] Example 1:

[0061] like Figures 1-7 As shown, Embodiment 1 of the present invention provides a hydraulic locking nut, comprising:

[0062] The assembly comprises a pull rod 1, a pressure block assembly, a cap 8, a relief bolt 9, and a piston 3. One end of the pull rod 1 has a pin hole 101. The pressure block assembly is coaxially sleeved on the outside of the pull rod 1 and can slide relative to the pull rod 1 along its axial direction. The piston 3 is located inside the pressure block assembly and is fixedly sleeved on the outside of the pull rod 1. The pull rod 1 has a raised surface, and the upper surface of the pull rod 1 is lower than the raised surface. The side of the piston 3 dynamically seals with the inner wall of the pressure block assembly, and the pressure block assembly dynamically seals with the pull rod 1. An oil cavity 17 is formed between the inside of the pressure block assembly and the piston 3, located on the side of the piston 3 facing the pin hole 101 and distributed circumferentially around the pull rod 1. An oil port 201 is provided on the pressure block assembly, and the oil port 201 connects with the oil cavity. 17 are connected; the cap 8 is located on the side of the pressure block assembly away from the pin hole 101 and is threaded with the pull rod 1. An annular cavity is formed between the inner wall of the cap 8 and the outer side of the pull rod 1; the end face of the pressure block assembly near the cap 8 extends into the annular cavity, and the inner wall of the cap 8 and the side of the pressure block assembly are dynamically sealed; multiple unloading bolts 9 are evenly screwed onto the cap 8 around the axis of the cap 8, and the end of each unloading bolt 9 facing the pressure block assembly extends into the annular cavity; in the locked state, the unloading bolts 9 are used to push the pressure block assembly to move toward the pin hole 101; in the unlocked state, the part of the unloading bolt 9 that extends into the annular cavity retracts into the cap 8 to reserve space for the pressure block assembly to retract.

[0063] It should be noted that this hydraulic locking nut is installed on the core base of the online rolling mill. Specifically, the pin hole 101 on the pull rod 1 is used to be installed on the core base with clearance fit to the pin. Notches for the pull rod 1 to be inserted are provided at the four corners of the rolling mill core. When installing the rolling mill core, first bend the pull rod 1 in the hydraulic locking nut. The pull rod 1 rotates around the pin at a certain angle to avoid the rolling mill core. Then place the rolling mill core on the core base. Then straighten the pull rod 1 and adjust it to a vertical position. At the same time as the pull rod 1 is straightened, it will be inserted into the notch of the rolling mill core. At this time, the pressure block assembly and the screw cap 8 are located directly above the notch.

[0064] Next, the cap 8 is manually tightened. The cap 8 is threaded with the pull rod 1 so that the cap 8 moves down. The end face of the pressure block assembly near the cap 8 extends into the annular cavity in the cap 8. As the cap 8 rotates, it pushes the pressure block assembly down together. As a result, the lower end face of the pressure block assembly presses tightly against the upper surface of the notch of the rolling mill core, so as to press the rolling mill core tightly onto the rolling mill base. Then, pressure is applied to the oil port 201 of the briquetting assembly to 50 MPa. The pressure in the oil chamber 17 acts on the piston 3. Since the piston 3 is blocked by the protruding surface on the tie rod 1, the piston 3 moves upward and acts on the protruding surface, thus giving the tie rod 1 a force towards the top, causing the tie rod 1 to be stretched. At the same time, the pressure in the oil chamber 17 acts on the briquetting assembly to drive the briquetting assembly to move downward again. The pressure exerted on the lower surface of the briquetting assembly on the mill core increases. At this time, a gap will be generated between the upper surface of the briquetting assembly and the cap 8. Then, the cap 8 is tightened again, and the cap 8 fits tightly against the upper surface of the briquetting assembly to eliminate the gap between the briquetting assembly and the cap 8. Finally, the pressure in the oil chamber 17 is released, and the oil port 201 is sealed to prevent water and dust from entering the oil chamber 17. As the pressure in the oil chamber 17 is released, the elastic force generated by the pull rod 1 in order to restore its original length points downwards. Driven by the elastic force of the pull rod 1, the pressure block assembly is pressed tightly against the mill core. The reaction force generated by the elastic force of the pull rod 1 between the pressure block assembly and the mill core acts directly on the pressure block assembly. The pressure block assembly is also tightly fitted with the cap 8, meaning that the reaction force will act on the cap 8. Since the cap 8 is threadedly engaged with the pull rod 1, when the cap 8 is subjected to a strong force along the axis of the pull rod 1, the cap 8 cannot be rotated.

[0065] If it is necessary to disassemble the rolling mill core for replacement or repair, the following two methods can be used. The first method requires ensuring the seal within the oil chamber 17 is intact. In this case, a high-pressure pump can be used to pressurize the oil chamber 17 to 50 MPa. Since the pressure block assembly is now firmly pressed against the rolling mill core, it cannot move further down. Therefore, the pressure within the oil chamber 17 will act on the piston 3. Because the piston 3 is limited by the pull rod 1, the pressure within the oil chamber 17 will also act on the pull rod 1. Thus, the force exerted by the oil chamber 17 on the pull rod 1 cancels out, or partially cancels out, the downward elastic force generated by the pull rod 1 itself. The pressure block assembly is no longer subjected to the reaction force generated by the elastic force. Alternatively, the reaction force generated by the elastic force on the pressure block assembly is greatly reduced, causing the cap 8 to be unloaded or the force on the cap 8 to be greatly reduced. At this point, the cap 8 can be easily unscrewed.

[0066] If the seal in the oil chamber 17 fails to meet the required pressure when pressurized by a high-pressure pump, then only the second method can be used for unlocking. Specifically, when locking, the lower end face of the unloading bolt 9 is lower than the inner end face 801 of the cap 8, meaning the bottom end of the unloading bolt 9 protrudes from the inner end face 801 of the cap 8. Therefore, the reaction force on the pressure block assembly acts on the lower end faces of multiple unloading bolts 9. At this time, by loosening multiple unloading bolts 9, the lower end face of the unloading bolt 9 retracts into the interior of the cap 8, meaning the lower end face of the unloading bolt 9 is higher than the inner end face 801. A gap is created between the upper surface of the pressure block assembly and the inner end face 801 of the cap 8. The upward reaction force on the pressure block assembly then drives the pressure block assembly to move upward, and the gap between the upper surface of the pressure block assembly and the inner end face 801 of the cap 8 gradually narrows. Since the length of the pull rod 1 that is stretched is generally only a few tenths of a millimeter, while the length of the portion of the unloading bolt 9 protruding from the inner end face 801 is greater than the length of the stretched pull rod 1, the pressure block assembly will not touch the inner end face 801 of the cap 8 even if it moves upward during the process of the pull rod 1 recovering its deformation. In this way, the cap 8 itself is not under stress, and the cap 8 can be easily unscrewed. That is, the unloading bolt 9 provides space for the pull rod 1 to recover its deformation, and the reserved space ensures that the pull rod 1 does not contact the cap 8 when recovering its deformation.

[0067] This ensures that even if the sealing performance of the hydraulic locking nut's oil chamber 17 fails, the cap 8 can still be easily loosened when fully locked. This avoids the problem of the cap 8 being unable to be loosened, which would prevent the movement from being disassembled and necessitate destructive oxygen cutting of the pull rod 1. This saves production costs, improves disassembly efficiency, and reduces disassembly difficulty.

[0068] Optionally, considering the strength of the cap 8 and the required mechanical locking force, 24 unloading bolts 9 are provided. See below. Figure 5 Drill holes at 15° intervals on the cap 8 to design 24 M16×1.5 bolt holes. The mechanical property grade of the M16×1.5 bolts is 10.9 or 12.9.

[0069] Optionally, to reduce friction and prevent rust, the 24 M16 high-strength bolts need to be lubricated before installation and then screwed into the cap 8. The clamping end of the unloading bolt 9 protrudes about 8mm-10mm from the inner end face 801 of the cap 8.

[0070] As a preferred embodiment Figure 4This is a schematic diagram showing the hydraulic locking nut in a vertical position. The pressure block assembly includes a cylinder body 2 and a pressure ring 4. The pressure ring 4 is coaxially arranged with the cylinder body 2 and fixed to the end face of the cylinder body 2 facing the cap 8. The cylinder body 2 has a shaft hole and a cylindrical cavity. The diameter of the shaft hole is smaller than the diameter of the cavity. The shaft hole of the cylinder body 2 is dynamically sealed to the side of the pull rod 1, and the shaft hole is located below the cavity. The piston 3 is sleeved on the pull rod 1 and is located inside the cavity of the cylinder body 2. An oil cavity 17 is formed between the lower surface of the piston 3 and the interior of the cylinder body 2. An oil inlet channel and an oil port 201 are provided on the cylinder body 2. One end of the oil inlet channel is connected to the oil cavity 17, and the other end is connected to the oil port 201. Furthermore, the diameter of the piston 3 is the same as the diameter of the cavity of the cylinder body 2, and the side of the piston 3 is dynamically sealed to the inner wall of the cavity. The lower surface of the pressure ring 4 is fixedly connected to the upper surface of the cylinder body 2, and the upper surface of the pressure ring 4 extends into the annular cavity of the cap 8 and dynamically seals with the inner wall of the cap 8.

[0071] Preferably, the pull rod 1 includes a rod body and a threaded sleeve 5. The inner wall of the threaded sleeve 5 is provided with an internal thread, and the outer surface is provided with an external thread. A threaded groove is provided on the rod body above the piston 3. The internal thread of the threaded sleeve 5 is screwed into the threaded groove on the rod body. An internal threaded hole is coaxially provided on the cap 8, and the internal threaded hole of the cap 8 is threadedly connected to the external thread on the outer surface of the threaded sleeve 5. It should be noted that the lower surface of the threaded sleeve 5 forms a raised surface. When the piston 3 moves upward, the lower end face of the threaded sleeve 5 will block the upper surface of the piston 3, thus limiting the piston 3.

[0072] It should be noted that the cap 8 has a cylindrical cavity that communicates with the internal threaded hole in the cap 8. The cavity and the internal threaded hole are coaxially arranged, and the cavity is lower than the internal threaded hole. Furthermore, the diameter of the cavity is larger than the diameter of the internal threaded hole, so that an inner end face 801 is formed on the cap 8. An annular cavity is formed between the outer surface of the threaded sleeve 5 and the inner wall of the cavity, and the upper surface of the pressure ring 4 extends into the annular cavity. A dynamic seal is formed between the inner wall of the cavity and the outer surface of the pressure ring 4 to improve the sealing performance.

[0073] Preferably, the inner diameter of the pressure ring 4 is larger than the outer diameter of the threaded sleeve 5, so that an annular cavity is formed between the inner surface of the pressure ring 4 and the outer surface of the threaded sleeve 5. Specifically, as shown... Figure 7 As shown, the pressure ring 4 has a bottom hole and a top hole sequentially arranged from low to high inside. The bottom hole and the top hole are coaxially arranged, with the diameter of the bottom hole being larger than the diameter of the top hole, and the depth of the bottom hole being greater than the depth of the top hole. Figure 3 and Figure 4 As shown, after the pressure ring 4 is assembled, the inner wall of the top hole of the pressure ring 4 contacts the outer surface of the threaded sleeve 5, while the inner wall of the bottom hole forms an annular cavity between the inner wall of the bottom hole and the outer surface of the threaded sleeve 5.

[0074] The purpose of setting up the annular cavity is to reserve installation space for the spring 6. The spring 6 is set in the annular cavity so that the bottom end of the spring 6 acts on the upper surface of the piston 3 and the top end of the spring 6 acts on the pressure ring 4.

[0075] When the cap 8 is tightened, the pressure ring 4 moves down and compresses the spring 6 from the top of the spring 6. When unlocking, the spring 6 returns to its original state and pushes the pressure ring 4 upward to speed up the unlocking process.

[0076] Preferred, such as Figure 3 and Figure 4 As shown, a dustproof ring 10, a guide belt 11, and an axial sealing ring 12 are sequentially arranged on the inner wall of the shaft hole of the cylinder body 2 along the axial direction of the cylinder body 2. The axial sealing ring 12 is closest to the oil cavity 17, while the dustproof ring 10 is installed at the lowest position. The dustproof ring 10 mainly serves to prevent dust from entering the oil cavity 17. The axial sealing ring 12 provides a sealing effect, preventing oil in the oil cavity 17 from leaking from the shaft hole.

[0077] Preferred, such as Figure 3 , Figure 4 and Figure 6 As shown, an outer groove 301 is formed on the outer surface of the piston 3, and an inner groove 302 is formed on the inner surface of the piston 3. Both the outer groove 301 and the inner groove 302 are annular grooves. An outer piston sealing ring 13 is provided in the outer groove 301, and an inner piston sealing ring 14 is provided in the inner groove 302. When the piston 3 is installed inside the cylinder 2, the outer piston sealing ring 13 in the outer groove 301 of the piston 3 is in sealing contact with the inner wall of the cylinder 2, while the inner piston sealing ring 14 in the inner groove 302 of the piston 3 is in sealing contact with the side of the pull rod 1. It should be noted that the outer piston sealing ring 13 and the inner piston sealing ring 14 play a sealing role to create a sealed environment in the oil chamber 17. It should be noted that the piston outer seal ring 13 and piston inner seal ring 14 are prone to aging. Once aging occurs, the piston outer seal ring 13 and piston inner seal ring 14 will have difficulty in achieving a good sealing effect. At this time, the sealing state of the oil chamber 17 is difficult to guarantee, so when the high-pressure pump pressurizes, the pressure in the oil chamber 17 is difficult to reach the preset value.

[0078] Preferably, a plurality of screw holes 401 are evenly provided on the pressure ring 4 around the axis of the pressure ring 4, and the screw holes 401 are countersunk holes, such as... Figure 4 As shown, the screw hole 401 is opened from the top of the pressure ring 4 towards the bottom. Further, as... Figure 4Multiple threaded holes, corresponding one-to-one with screw holes 401, are evenly distributed around the axis of cylinder 2 on the upper surface of cylinder 2. When assembling the pressure ring 4, the pressure ring 4 is placed on top of cylinder 2, and then rotated to adjust its angle so that the screw holes 401 of the pressure ring 4 are aligned with the threaded holes on cylinder 2. Then, screws 15 are inserted into the screw holes 401 on the pressure ring 4 and tightened. The bottom end of screw 15 is screwed into the threads of cylinder 2, while the top end of screw 15 enters the screw hole 401, thus fixing cylinder 2 and pressure ring 4 together. It should be noted that screw 15 is an internal hexagonal screw, and the top end of screw 15 is either below the upper surface of pressure ring 4 or flush with the upper surface of pressure ring 4. This ensures that the stress-relieving bolt 9 does not act on screw 15.

[0079] Preferred, such as Figure 3 and Figure 4 As shown, a washer 7 is fitted onto the threaded sleeve 5. The inner wall of the washer 7 contacts the threaded sleeve 5, and the outer surface of the washer 7 contacts the inner wall of the cap 8. The washer 7 is located between the upper surface of the pressure ring 4 and the inner end face 801 of the cap 8. The washer 7 is a metal plate, preferably a steel plate. It should be noted that if the stress relief bolt 9 acts directly on the upper surface of the pressure ring 4, the following problems will occur. First, the area on which the stress relief bolt 9 acts on the pressure ring 4 is small, while the hardness of the pressure ring 4 is 22HRC-32HRC, which is relatively low. Therefore, the stress relief bolt 9 will damage the pressure ring 4. Second, multiple screw holes 401 are provided on the upper surface of the pressure ring 4. Since there are multiple stress relief bolts 9, it is difficult for the stress relief bolt 9 to avoid the screw holes 401 on the pressure ring 4, which may cause the stress relief bolt 9 to act on the screw holes 401, resulting in uneven force on the stress relief bolt 9. The washer 7 has high hardness, so the unloading bolt 9 acts directly on the washer 7, instead of directly on the upper surface of the pressure ring 4. Furthermore, the contact area between the washer 7 and the upper surface of the pressure ring 4 is large, thus preventing damage to the upper surface of the pressure ring 4. In addition, the unloading bolt 9 acts on the upper surface of the washer 7, while the lower surface of the washer 7 acts on the upper surface of the pressure ring 4. This avoids the unloading bolt 9 directly acting on the screw hole 401 of the pressure ring 4, resulting in a more even distribution of force on the unloading bolt 9.

[0080] It should be noted that before placing the washer 7, calcium sulfonate grease should be evenly applied to both sides of the washer 7. One of the main functions of calcium sulfonate grease lubricant is lubrication and rust prevention.

[0081] Optionally, the thickness of washer 7 is 18mm, the surface hardness of washer 7 after quenching and tempering is 42HRC-45HRC, and the surface roughness Ra of the front and back is 0.4μm.

[0082] To improve the sealing performance between the cap 8 and the pressure ring 4, such as Figure 7As shown, a mounting groove 402 is provided on the side of the pressure ring 4. The mounting groove 402 is an annular groove, and an O-ring 16 is provided inside the mounting groove 402. (See image below.) Figure 3 When the hydraulic locking nut is assembled, the inner wall of the cap 8 contacts the side of the pressure ring 4, and the O-ring 16 contacts the inner wall of the cap 8, so that the O-ring 16 can provide a good sealing effect.

[0083] The specific working principle of this hydraulic locking nut is as follows:

[0084] When installing the mill core, first bend the pull rod 1 in the hydraulic locking nut. Rotate the pull rod 1 around the pin shaft at a certain angle to avoid the mill core. Then place the mill core on the core base. Then straighten the pull rod 1 and adjust it to a vertical position. As the pull rod 1 straightens, it will be inserted into the notch of the mill core.

[0085] Next, manually tighten the unloading bolt 9 so that the bottom end of the unloading bolt 9 is lower than the inner end face 801 of the cap 8 to leave space for the pull rod 1 to recover its deformation.

[0086] Then, manually tighten the cap 8. The cap 8 moves downward on the screw sleeve 5. The cap 8 pushes the washer 7 to act on the pressure ring 4, thereby pushing the cylinder 2 downward. The lower end face of the cylinder 2 will press tightly against the upper surface of the notch of the rolling mill core, so as to press the rolling mill core tightly onto the rolling mill base.

[0087] Then, pressure of 45 MPa-50 MPa, preferably 45 MPa, is applied into the oil port 201 of the pressure block assembly. The pressure in the oil chamber 17 acts on the piston 3. Since the upper surface of the piston 3 is held against the threaded sleeve 5 on the pull rod 1, a force is applied to the pull rod 1 upwards, causing it to be stretched. At the same time, the pressure in the oil chamber 17 acts on the cylinder 2, driving it to move downwards again. The downward movement of the cylinder 2 causes the pressure ring 4 to move downwards as well. Under the influence of gravity, the washer 7 moves downwards as well. At this time, a small gap is generated between the upper surface of the washer 7 and the inner end face 801 of the cap 8. Then, the cap 8 is tightened again, and the unloading bolt 9 on the cap 8 pushes the washer 7 to press tightly against the upper surface of the pressure ring 4.

[0088] Then, the pressure in the oil chamber 17 is released, and the oil port 201 is sealed to prevent water and dust from entering the oil chamber 17. Since the pressure in the oil chamber 17 is released, the elastic force generated by the pull rod 1 to restore its original length is downward. Driven by the elastic force of the pull rod 1, the cylinder body 2 is pressed tightly against the mill core. The reaction force generated by the elastic force of the pull rod 1 acts directly on the cylinder body 2. Since the washer 7 is in direct contact with the relief bolt 9 at this time, the reaction force will act on the relief bolt 9.

[0089] At this point, the mill core can be disassembled using the following two methods. The first method does not require consideration of the sealing performance of the oil chamber 17. Specifically, by loosening multiple relief bolts 9, the lower end face of the relief bolt 9 retracts into the interior of the cap 8, meaning the lower end face of the relief bolt 9 is higher than the inner end face 801. At this time, a gap is created between the upper surface of the washer 7 and the inner end face 801 of the cap 8. The cylinder body 2 is driven upward by the upward reaction force, which moves the pressure ring 4 and the washer 7 upward. The gap creates space for the pull rod 1 to recover its deformation. Therefore, during the recovery process of the pull rod 1, the washer 7 moves upward but does not contact the inner end face 801 of the cap 8. Thus, the cap 8 itself is not under stress, and the cap 8 can be easily unscrewed.

[0090] The second method requires ensuring the oil chamber 17 is properly sealed. Specifically, a high-pressure pump is used to repressurize the oil chamber 17 to 45-50 MPa. Since the cylinder 2 is now pressed tightly against the rolling mill mechanism, it cannot move further. Therefore, the pressure inside the oil chamber 17 acts on the piston 3. Because the piston 3 is blocked by the threaded sleeve 5 on the pull rod 1, the pressure inside the oil chamber 17 acts on the pull rod 1. Thus, the force acting on the pull rod 1 cancels out, or partially cancels out, the downward elastic force generated by the pull rod 1 itself, resulting in the cap 8 being unloaded or experiencing a significantly reduced force. At this point, the cap 8 can be easily unscrewed.

[0091] Example 2:

[0092] A method for using a hydraulic locking nut, the method including a locking method and a loosening method under the condition of air pressure relief in the oil chamber 17;

[0093] The locking method includes the following steps:

[0094] First, after the mill core is installed on the core base, the hydraulic locking nut is raised, and then the unloading bolt 9 is tightened so that the end of the unloading bolt 9 protrudes about 8mm-10mm from the inner end face 801 of the cap 8.

[0095] The second step is to manually tighten the cap 8 using tools. The cap 8 is moved down to press the cylinder 2 firmly onto the movement base until it can no longer be tightened manually.

[0096] The third step is to use a high-pressure pump to pressurize the oil port 201. The pressure in the oil chamber 17 gradually increases, and the cylinder 2 is pressed down again under the pressure. A gap is generated between the washer 7 and the lower surface of the relief bolt 9. Then, use a tool to tighten the cap 8 again. The cap 8 drives the relief bolt 9 to move down again until the lower surface of the relief bolt 9 is tightly pressed against the upper surface of the washer 7 to eliminate the gap between the washer 7 and the relief bolt 9.

[0097] The fourth step is to use a high-pressure pump to relieve the pressure in the oil chamber 17.

[0098] like Figure 5 As shown, there are 24 unloading bolts 9. For ease of description, we will refer to them as follows: Figure 5 The topmost unloading bolt 9 is named A, and then the remaining unloading bolts 9 are named B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, I, S, T, U, V, W and X in a counterclockwise direction.

[0099] The release method under the depressurized state of oil chamber 17 includes the following steps:

[0100] Manually tighten the cap 8, and use a torque wrench or socket to turn the first bolt A in the opposite direction by a turns, and then turn the bolt M, which is symmetrical to bolt A, in the opposite direction by a turns.

[0101] Loosen bolt B by turning it a times. Then loosen bolt N, which is symmetrical to bolt B, by turning it a times.

[0102] Then, loosen the remaining unloading bolts 9 by turning the cap 8 counterclockwise, turning each unloading bolt 9 by a turns. This completes the first loosening of the unloading bolts 9.

[0103] Next, repeat the above steps to loosen the unclog bolts 9 again, turning each bolt 9 by 'a' turns. Repeat this loosening process twice, until all the unclog bolts 9 are essentially moved to their designated positions.

[0104] Then manually loosen the cap 8, and then manually bend the pull rod 1 so that the pull rod 1 is tilted and disengages from the notch on the mill core.

[0105] When the lock nut seal is damaged and the pressure in oil chamber 17 is insufficient during the assembly of the movement, it is not necessary to replace the seal immediately. Temporary locking can be achieved by using the relief bolt 9. The specific steps are as follows:

[0106] The first step is to install the mill core on the core base and then raise the hydraulic locking nut.

[0107] The second step is to manually tighten the cap 8 using tools. The cap 8 is moved down to press the cylinder 2 firmly onto the movement base until it can no longer be tightened manually.

[0108] The third step is to tighten the unloading bolts 9 symmetrically and evenly. The lower surface of the unloading bolts 9 is pressed tightly against the upper surface of the washer 7 so that the washer 7 presses tightly against the pressure ring 4 and the cylinder 2, and the cylinder 2 is pressed tightly against the mechanism base.

[0109] In the description of this invention, it should be noted that the terms "upper" and "lower," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0110] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hydraulic locking nut, characterized in that, include: A pull rod (1), a pressure block assembly, a screw cap (8), a relief bolt (9), and a piston (3); one end of the pull rod (1) is provided with a pin hole (101); The pressure block assembly is coaxially sleeved on the outside of the pull rod (1) and can slide relative to the pull rod (1) along the axial direction. The piston (3) is located inside the pressure block assembly and is fixedly sleeved on the outside of the pull rod (1). The pull rod (1) has a protruding surface. The upper surface of the pull rod (1) is lower than the protruding surface. The side of the piston (3) is dynamically sealed to the inner wall of the pressure block assembly. The pressure block assembly is dynamically sealed to the pull rod (1). The pressure block assembly and the piston (3) cooperate to form an oil cavity located on the side of the piston facing the pin hole (101) and distributed circumferentially around the pull rod (1). The pressure block assembly is provided with an oil port (201) which is connected to the oil cavity. The cap (8) is located on the side of the pressure block assembly away from the pin hole (101) and is threadedly engaged with the pull rod (1). An annular cavity is formed between the inner wall of the cap (8) and the outer side of the pull rod (1). The end face of the pressure block assembly near the cap (8) extends into the annular cavity, and the inner wall of the cap (8) is dynamically sealed to the side of the pressure block assembly. Multiple unloading bolts (9) are evenly screwed onto the cap (8) around the axis of the cap (8), and one end of each unloading bolt (9) facing the pressure block assembly extends into the annular cavity; In the locked state, the unloading bolt (9) is used to push the pressure block assembly toward the pin hole (101); in the unlocked state, the portion of the unloading bolt (9) that extends into the annular cavity retracts into the cap (8) to reserve space for the pressure block assembly to retract.

2. A hydraulic locking nut according to claim 1, characterized in that, The pressing block assembly includes a cylinder (2) and a pressing ring (4), the pressing ring (4) being coaxially arranged with the cylinder (2), and the pressing ring (4) being fixed to the end face of the cylinder (2) facing the screw cap (8); The cylinder (2) is dynamically sealed to the side of the pull rod (1), and the inner wall of the cylinder (2) is dynamically sealed to the side of the piston (3); The oil chamber is formed between the inside of the cylinder (2) and the piston (3), and the oil port (201) is opened on the cylinder (2); The pressure ring (4) extends into the annular cavity of the cap (8) with its end face facing the cap (8), and dynamically seals with the inner wall of the cap (8).

3. A hydraulic locking nut according to claim 2, characterized in that, The pull rod (1) includes a rod body and a threaded sleeve (5). The inner wall of the threaded sleeve (5) is provided with an internal thread, and the outer surface is provided with an external thread. The threaded sleeve (5) and the rod body are engaged by the internal thread. The screw sleeve (5) is located on the side of the piston (3) away from the pin hole (101), and the screw cap (8) is threadedly installed on the screw sleeve (5). One end of the screw sleeve (5) abuts against the end face of the piston (3) facing the screw cap (8).

4. A hydraulic locking nut according to claim 3, characterized in that, The hydraulic locking nut includes a washer (7), which is sleeved on the threaded sleeve (5) and can slide relative to the threaded sleeve (5) along its axial direction. The outer side of the washer (7) dynamically seals with the inner wall of the cap (8), and the washer (7) is located between the pressure ring (4) and the unloading bolt (9).

5. A hydraulic locking nut according to claim 2, characterized in that, At least one piston inner sealing ring (14) is provided between the inner surface of the piston (3) and the side of the pull rod (1), at least one piston outer sealing ring (13) is provided between the outer surface of the piston (3) and the inner wall of the cylinder (2), and at least one axial sealing ring (12) is provided between the cylinder (2) and the pull rod (1).

6. A hydraulic locking nut according to claim 3, characterized in that, The inner diameter of the pressure ring (4) is larger than the outer diameter of the threaded sleeve (5). An annular cavity is formed between the inner surface of the pressure ring (4) and the outer surface of the threaded sleeve (5). A spring (6) is sleeved in the annular cavity. When the spring (6) is in a compressed state, the two ends of the spring (6) are in contact with the piston (3) and the pressure ring (4) respectively.

7. A hydraulic locking nut according to claim 5, characterized in that, Along the axial direction of the pull rod (1), a dustproof ring (10) and a guide strip (11) are sequentially provided between the cylinder body (2) and the side of the pull rod (1), and the axial sealing ring (12) is located between the guide strip (11) and the piston (3).

8. A hydraulic locking nut according to claim 2, characterized in that, The cylinder body (2) has a threaded hole on the end face facing the pressure ring (4), and the pressure ring (4) has a screw hole (401) corresponding to the threaded hole. The threaded hole and the screw hole (401) are connected by a screw.

9. A method for using a hydraulic locking nut, characterized in that, The method of use employs a hydraulic locking nut as described in any one of claims 1-8, and the method of use includes a locking method and a loosening method under the condition of depressurization of the oil chamber. The locking method includes the following steps: First, after the mill core is installed on the core base, the hydraulic locking nut is raised, the unloading bolt (9) is coated with grease and screwed into the cap (8), then the cap (8) is screwed into the pull rod (1), and then the unloading bolt (9) is screwed into the annular cavity of the cap (8). The second step is to use a tool to tighten the cap (8) so that the pressure block assembly is pressed tightly onto the movement base; The third step is to use a high-pressure pump to pressurize the oil port (201). The pressure in the oil chamber gradually increases, and the pressure block assembly is pressed down again under the pressure drive. A gap is generated between the pressure block assembly and the unloading bolt (9). Then, use a tool to tighten the cap (8) again to eliminate the gap between the pressure block assembly and the unloading bolt (9). The fourth step is to use a high-pressure pump to relieve the pressure inside the oil chamber; The release method under the vented state of the oil chamber includes the following steps: First, use a torque wrench or socket to turn the first unloading bolt (9) in the opposite direction by a turns, and then turn the unloading bolt (9) that is symmetrical to the previous unloading bolt (9) about the axis of the cap (8) in the opposite direction, so that the unloading bolt (9) rotates a turns. The second step is to loosen the unloading bolt (9) adjacent to the first unloading bolt (9) in the first step in the counterclockwise direction of the screw cap (8), so that the unloading bolt (9) rotates a turns. Then, tighten the unloading bolt (9) that is symmetrical to the unloading bolt (9), so that the unloading bolt (9) rotates a turns. Third step, loosen the remaining unloading bolts (9) in the counterclockwise direction of the screw cap (8), turning each unloading bolt (9) a turns; Fourth step, repeat steps one through three until all unloading bolts (9) are completely loosened; Fifth step, use a tool to loosen the screw cap (8).

10. A method of using a hydraulic locking nut according to claim 9, characterized in that, In the third step of the locking method, the pressure applied by the high-pressure pump to the oil port (201) is 45 MPa to 50 MPa.

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