Thread locking structure for hydraulic cylinder bottom
By employing a combined sealing structure of O-ring elastic seal and trapezoidal sealing section in the threaded locking structure at the bottom of the hydraulic cylinder, combined with epoxy sealing colloid and fine thread design, the problems of insufficient sealing performance and poor anti-loosening effect are solved, achieving stable connection and durability under high pressure and high frequency vibration conditions.
Patent Information
- Application Number
- CN202522177936.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-15
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-10-15
AI Technical Summary
The existing threaded locking structure at the bottom of the hydraulic cylinder has problems such as insufficient sealing performance, poor anti-loosening effect, insufficient assembly convenience and precision, and poor durability. In particular, under high pressure and high frequency vibration conditions, hydraulic oil leakage, loose connection and corrosion wear are prone to occur.
The system employs an O-ring elastic seal and a stepped sealing section, combined with epoxy sealant to form a multi-layer sealing structure. The fine thread design and oxidized thread section increase self-locking friction. Through the combination of the stepped sealing section and the sealant, multiple anti-loosening and sealing effects are achieved, and a wear-resistant and corrosion-resistant layer is formed on the thread surface.
It achieves sealing reliability and connection stability under high pressure and high frequency vibration conditions, reduces hydraulic oil leakage and corrosion wear, extends service life, and improves assembly accuracy and anti-loosening performance.
Smart Images
Figure CN224679823U_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of hydraulic cylinder technology, and in particular to a threaded locking structure for the bottom of a hydraulic cylinder. Background Technology
[0002] In the field of hydraulic cylinder technology, the threaded locking structure at the cylinder bottom is a core component for achieving a stable connection between the hydraulic cylinder and a fixed surface, such as an equipment frame, work base, or hydraulic system installation platform. Its performance directly determines the installation stability and operational reliability of the hydraulic cylinder during operation. This type of structure typically uses the base plate at the bottom of the hydraulic cylinder body as the connection foundation. Fixing components are assembled through pre-drilled mounting holes on the base plate, and locking bolts, through the threaded engagement of the mounting holes and fixing components, secure the entire hydraulic cylinder to the fixed surface. Simultaneously, sealing components must block hydraulic oil leakage channels, and anti-loosening designs must resist vibrations and axial forces generated during hydraulic system operation. This ensures that the hydraulic cylinder maintains a reliable connection with the fixed surface even under high pressure and high-frequency vibration conditions, preventing the normal operation of the hydraulic system from being affected by loose connections or seal failure.
[0003] However, existing threaded locking structures at the bottom of hydraulic cylinders still suffer from insufficient sealing performance in practical applications. Traditional structures often use a single sealing ring or thread sealant for sealing. The former is prone to misalignment and deformation due to assembly errors, while the latter is prone to creating sealing dead zones due to uneven filling of the thread gaps. Especially in high-pressure hydraulic environments, this can easily lead to hydraulic oil leakage or the intrusion of external dust and moisture into the fixed parts. Furthermore, the anti-loosening effect is poor. Existing structures generally rely on the self-locking property of the threads or simple gaskets for anti-loosening. When the hydraulic cylinder is under high-frequency vibration and impact conditions, relative slippage can easily occur between the threads, leading to loosening of the connection. This necessitates frequent shutdowns for maintenance, affecting equipment operation. The system suffers from several drawbacks. Firstly, it lacks efficiency, ease of assembly, and precision. The connection between the fasteners and the base plate primarily uses bolts rather than rigid welding, which easily leads to installation benchmark deviations. Furthermore, the tightening end design of the locking bolts lacks adaptability, causing slippage when the wrench is engaged, making it difficult to guarantee the assembly precision of the threaded fit. Secondly, its durability is poor. The threaded sections are mostly ordinary coarse threads without specific anti-corrosion and wear-resistant treatment. Long-term contact with hydraulic oil and humid environments easily leads to corrosion and wear, increasing the threaded fit clearance and further exacerbating sealing failure and loosening issues, thus shortening the overall structure's service life. Therefore, a threaded locking structure for the bottom of the hydraulic cylinder needs to be designed to address these problems. Utility Model Content
[0004] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a threaded locking structure for the bottom of a hydraulic cylinder.
[0005] The technical solution of the present invention to solve the above technical problems is as follows: it includes a hydraulic cylinder body, a base plate is fixedly provided at the bottom of the hydraulic cylinder body, mounting holes are provided at the four corners of the base plate, a fixing member is welded to the bottom of the mounting hole, and a locking bolt is provided inside the fixing member. The upper inner side of each fastener is provided with an injection groove, the middle of each injection groove is provided with a first fitting groove, the bottom inner side of each fastener is provided with a threaded groove, and the bottom of each fastener is provided with a second fitting groove. The locking bolt is provided with a tightening end, an inlet section and a threaded section from top to bottom, and a ladder seal section is provided on the outer side of the inlet section.
[0006] Furthermore, each of the first fitting grooves is fitted with a first sealing ring, which is an elastic ring with an O-shaped cross-section. The ladder sealing sections are symmetrically protruding from the outer circumferential surface of the inlet section. The outer diameter of the ladder sealing section is smaller than the diameter of the mounting hole, and the outer diameter of the ladder sealing section is larger than the inner diameter of the first sealing ring.
[0007] Furthermore, the interior of each of the injection grooves is provided with epoxy sealant. All tightening ends are regular hexagons, and the outer circumferential surface of each tightening end is provided with symmetrically distributed wrench locking planes.
[0008] Furthermore, each of the threaded segments is threadedly connected to the corresponding thread groove, and the length of the threaded segment is 1.5-2 times the length of the thread groove.
[0009] Furthermore, a second sealing ring is fitted inside each of the second fitting grooves, and the second sealing ring is an elastic ring with an O-shaped cross-section.
[0010] Furthermore, both the thread groove and the thread segment are fine threads with a pitch of 1.5-2 mm and a thread profile angle of 60°. The surface of the thread is oxidized to form a wear-resistant and corrosion-resistant layer.
[0011] The beneficial effects of this invention are as follows: 1. The O-ring elastic first sealing ring, which engages with the first fitting groove, forms an interference fit with the trapezoidal sealing section of the locking bolt. The outer diameter of the trapezoidal sealing section is larger than the inner diameter of the first sealing ring. When screwed in, the sealing ring is squeezed and elastically deformed, tightly fitting the inner wall of the fixing part and the outer circumference of the trapezoidal sealing section, forming the first mechanical seal. At the same time, the epoxy sealant in the injection groove fills the gap between the threaded section and the threaded groove. After curing, it forms a high-strength sealing layer, blocking the leakage channel of the threaded mating surface, forming the second colloidal seal. This effectively solves the problem of single sealing and easy leakage in traditional threaded connections, and can meet the sealing requirements of high-pressure liquids or gases in hydraulic systems.
[0012] 2. The O-ring elastic second sealing ring in the second fitting groove at the bottom of the fastener tightly fits the fastener and the external mating parts, forming a third protective seal. This not only prevents external dust, moisture, and other impurities from entering the fastener and contaminating the threaded mating surface, but also further intercepts hydraulic oil that may leak from the inside, achieving a comprehensive sealing effect that prevents internal leakage and external intrusion. The length of the thread section is designed to be 1.5-2 times that of the thread groove, extending the thread engagement length, increasing the number of contact teeth and friction between the threads, and reducing the relative slippage of the threads under vibration conditions. At the same time, the thread groove and thread section adopt fine-pitch threads with a pitch of 1.5-2mm. The tooth profile characteristics of fine-pitch threads can increase the self-locking friction, reduce the risk of loosening, and provide a basic guarantee for preventing loosening.
[0013] 3. After the epoxy sealant cures, it firmly bonds the locking bolt and the fastener into a whole through adhesive force, preventing relative rotation between the two. At the same time, the elastic rebound force generated by the compression of the first sealing ring by the ladder sealing section forms a radial locking limit on the locking bolt, further restricting the axial and circumferential displacement of the bolt. The multiple anti-loosening structures work together to ensure that the device can maintain a stable connection even under harsh working conditions such as high-frequency vibration and impact. The surface of the thread groove and thread section is oxidized to form a wear-resistant and anti-corrosion layer, which can reduce mechanical wear during thread mating, extend the service life of the thread, and resist the erosion of hydraulic oil, external acids and alkalis and other corrosive media, adapting to complex working environments such as humidity and oil. Attached Figure Description
[0014] Figure 1 A three-dimensional structural diagram of a threaded locking structure for the bottom of a hydraulic cylinder; Figure 2 A three-dimensional bottom view of a threaded locking structure for the bottom of a hydraulic cylinder; Figure 3 A front view of a threaded locking structure for the bottom of a hydraulic cylinder; Figure 4 An exploded three-dimensional structural diagram of a fastener and locking bolt for a threaded locking structure at the bottom of a hydraulic cylinder; Figure 5 A cross-sectional view of a fastener for a threaded locking structure at the bottom of a hydraulic cylinder; Figure 6 This is a front view of a locking bolt for a threaded locking structure at the bottom of a hydraulic cylinder.
[0015] In the diagram: 1. Hydraulic cylinder body; 2. Base plate; 201. Mounting hole; 3. Fixing component; 301. Glue injection groove; 302. Threaded groove; 303. First fitting groove; 304. Second fitting groove; 4. Locking bolt; 401. Tightening end; 402. Inlet section; 403. Threaded section; 404. Ladder sealing section; 5. First sealing ring; 6. Second sealing ring. Detailed Implementation
[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.
[0017] Please see Figures 1-6 The present invention provides a technical solution: a threaded locking structure for the bottom of a hydraulic cylinder, comprising a hydraulic cylinder body 1, characterized in that: a base plate 2 is fixedly provided at the bottom of the hydraulic cylinder body 1, mounting holes 201 are provided at the four corners of the base plate 2, a fixing member 3 is welded to the bottom of the mounting holes 201, and a locking bolt 4 is provided inside the fixing member 3. The upper inner side of the fastener 3 is provided with an injection groove 301, the middle part of the injection groove 301 is provided with a first fitting groove 303, the bottom inner side of the fastener 3 is provided with a threaded groove 302, and the bottom of the fastener 3 is provided with a second fitting groove 304. The locking bolt 4 is provided with a tightening end 401, an inlet section 402 and a threaded section 403 from top to bottom, and a ladder sealing section 404 is provided on the outer side of the inlet section 402.
[0018] The first fitting groove 303 is equipped with a first sealing ring 5. The first sealing ring 5 is an elastic ring with an O-shaped cross section. When the trapezoidal sealing section 404 is squeezed, it can undergo elastic deformation. Through its own elastic force, it fits tightly with the trapezoidal sealing section 404, achieving a preliminary seal between the trapezoidal sealing section 404 and the fixing member 3. At the same time, the rebound force generated by the elastic deformation forms a locking limit on the locking bolt 4, enhancing the anti-loosening effect of the mechanical connection. The trapezoidal sealing sections 404 are symmetrically protruding from the outer circumferential surface of the inlet section 402. The outer diameter of the trapezoidal sealing section 404 is smaller than the diameter of the mounting hole 201, and the outer diameter of the trapezoidal sealing section 404 is larger than the inner diameter of the first sealing ring 5. The outer diameter being smaller than the diameter of the mounting hole 201 ensures that the trapezoidal sealing section 404 can pass smoothly through the mounting hole 201, facilitating the overall assembly of the locking bolt 4. The outer diameter being larger than the inner diameter of the first sealing ring 5 allows the trapezoidal sealing section 404 to precisely compress the first sealing ring 5 during the tightening of the locking bolt 4, causing it to undergo effective elastic deformation. This balances ease of assembly with sealing reliability, achieving a synergistic effect of mechanical sealing and limiting.
[0019] The injection groove 301 is filled with epoxy sealant. The injection groove 301 can contain and guide the epoxy sealant, ensuring that the sealant is evenly distributed in the mating area between the locking bolt 4 and the fastener 3. After the sealant fills the gap between the threaded section 403 and the threaded groove 302, it cures to form a high-strength sealing layer, which can not only block the leakage channel of liquid or gas, but also firmly connect the locking bolt 4 and the fastener 3 through the adhesive force of the sealant, greatly improving the vibration resistance and anti-loosening performance. All tightening ends 401 are regular hexagons. The outer circumference of the tightening end 401 is provided with symmetrically distributed wrench locking planes. The regular hexagonal structure and the symmetrical wrench locking planes cooperate to make the wrench and the tightening end 401 stably engaged, avoiding slippage during tightening and ensuring accurate torque transmission. This facilitates the operator to efficiently complete the tightening and loosening of the locking bolt 4, while ensuring the fitting accuracy of the thread section 403 and the thread groove 302, laying the foundation for the subsequent sealing structure to play its role.
[0020] All threaded sections 403 are threadedly connected to the corresponding threaded grooves 302. The length of the threaded section 403 is 1.5-2 times that of the threaded groove 302. The extended threaded section 403 increases the number of meshing teeth and the contact area with the threaded groove 302, improves the load-bearing capacity and pull-out resistance of the threaded connection, and reduces the relative slippage between threads under vibration conditions. The excess length of the threaded section 403 can fully adhere to the epoxy sealant, ensuring that the sealant fills the thread fit gap, further enhancing the sealing and anti-loosening effect.
[0021] The second fitting groove 304 is equipped with a second sealing ring 6. The second sealing ring 6 is an elastic ring with an O-shaped cross section. The second fitting groove 304 positions the second sealing ring 6. The O-shaped elastic structure makes it fit tightly against the bottom of the fixing part 3 and the external mating parts. Together with the first sealing ring 5 and the epoxy sealant, it forms a triple sealing system, which effectively prevents external dust, moisture and other impurities from entering the interior of the fixing part 3, while preventing internal hydraulic oil leakage and improving the overall sealing reliability.
[0022] Both thread groove 302 and thread section 403 are fine-pitch threads with a pitch of 1.5-2mm and a thread angle of 60°. The surface of the thread is oxidized to form a wear-resistant and corrosion-resistant layer. The small pitch and 60° thread angle of the fine-pitch thread can increase the self-locking friction between the threads, reduce the risk of loosening, and provide more filling space for the epoxy sealant. The oxidized wear-resistant and corrosion-resistant layer can reduce wear during thread mating, resist the erosion of the threads by hydraulic oil and external corrosive media, extend the service life of the threaded connection, and further enhance the durability of anti-loosening and sealing when combined with the sealant.
[0023] Working principle: First, the first sealing ring 5 is engaged in the corresponding first fitting groove 303. The limiting effect of the fitting groove 303 is used to ensure that the initial position of the first sealing ring 5 is accurate and to avoid displacement during installation. At the same time, the fixing part 3 is welded to the bottom of the mounting hole 201 of the base plate 2 to form a rigid base structure. Then, use a wrench to insert the threaded section 403 of the locking bolt 4 into the mounting hole 201, so that the threaded section 403 is initially screwed into the upper part of the thread groove 302. At this time, control the bottom of the tightening end 401 to leave an appropriate gap with the cross section of the mounting hole 201. Next, epoxy sealant is added into the injection groove 301. With the guidance of the injection groove 301, the sealant is evenly distributed. Since the threaded section 403 has been partially screwed into the threaded groove 302, the surface of the upper threaded section 403 is naturally covered with epoxy sealant. As it continues to be screwed down, the sealant is evenly carried into the thread mating surfaces. The fine thread design of the threaded section 403 and the threaded groove 302 increases the thread contact area, allowing the sealant to fully fill the thread gap and form a continuous sealing interface. After the threaded section 403 is fully screwed in, the lower inclined surface of the trapezoidal sealing section 404 of the locking bolt 4 contacts the first sealing ring 5 and generates a squeezing effect. The inclined surface design of the trapezoidal sealing section 404 makes the force evenly distributed radially, causing the first sealing ring 5 to undergo elastic deformation. The amount of deformation is controlled by the depth of the first fitting groove 303 to ensure that the first sealing ring 5 generates sufficient contact pressure to achieve sealing, but does not undergo excessive deformation leading to failure. The elastic force of the first sealing ring 5 reacts to the trapezoidal sealing section 404, causing the locking bolt 4 to be fully engaged inside the fixing member 3, forming a preliminary mechanical seal. Finally, after the epoxy sealant solidifies, a cured adhesive layer with high strength and good temperature resistance is formed. This adhesive layer not only fills all the gaps between the threaded section 403 and the threaded groove 302, but also forms a sealing gasket layer in the injection groove 301. The adhesive force of the adhesive firmly combines the locking bolt 4 and the fastener 3 into a whole, improving the vibration resistance of the threaded connection.
[0024] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. 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 threaded locking structure for the bottom of a hydraulic cylinder, comprising a hydraulic cylinder body (1), characterized in that: The bottom of the hydraulic cylinder body (1) is fixedly provided with a base plate (2), and mounting holes (201) are provided at the four corners of the base plate (2). Fixing parts (3) are welded to the bottom of the mounting holes (201), and locking bolts (4) are provided inside the fixing parts (3). Each of the fasteners (3) has an injection groove (301) on the upper inner side, a first fitting groove (303) in the middle of the injection groove (301), a threaded groove (302) on the bottom inner side of the fasteners (3), and a second fitting groove (304) at the bottom of the fasteners (3). The locking bolt (4) is provided with a tightening end (401), an inlet section (402) and a threaded section (403) from top to bottom, and a ladder sealing section (404) is provided on the outer side of the inlet section (402).
2. The threaded locking structure for the bottom of a hydraulic cylinder according to claim 1, characterized in that: The first fitting groove (303) is fitted with a first sealing ring (5), which is an elastic ring with an O-shaped cross section; The ladder sealing sections (404) are symmetrically protruding on the outer circumferential surface of the inlet section (402). The outer diameter of the ladder sealing section (404) is smaller than the diameter of the mounting hole (201), and the outer diameter of the ladder sealing section (404) is larger than the inner diameter of the first sealing ring (5).
3. The threaded locking structure for the bottom of a hydraulic cylinder according to claim 1, characterized in that: The interior of each of the glue injection tanks (301) is provided with epoxy sealant; All tightening ends (401) are regular hexagons, and the outer circumferential surface of the tightening end (401) is provided with symmetrically distributed wrench locking planes.
4. The threaded locking structure for the bottom of a hydraulic cylinder according to claim 1, characterized in that: Each threaded segment (403) is threadedly connected to the corresponding threaded groove (302), and the length of the threaded segment (403) is 1.5-2 times that of the threaded groove (302).
5. The threaded locking structure for the bottom of a hydraulic cylinder according to claim 1, characterized in that: The second fitting groove (304) is fitted with a second sealing ring (6), which is an elastic ring with an O-shaped cross section.
6. The threaded locking structure for the bottom of a hydraulic cylinder according to claim 1, characterized in that: The threaded groove (302) and the threaded section (403) are both fine threads with a pitch of 1.5-2mm and a thread profile angle of 60°. The surface of the thread is oxidized to form a wear-resistant and corrosion-resistant layer.