Piston rod for hydraulic oil cylinder

Abstract

The piston rod for the hydraulic oil cylinder comprises a piston rod body, a protective layer is arranged on the surface of the piston rod body, an inner connecting end is arranged at one end of the piston rod body, an outer connecting end is arranged at the other end of the piston rod body, and a fixing ring is arranged at the end, close to the outer connecting end, of the piston rod body. The outer side of the piston rod body is sleeved with a protective cover in a telescopic folding mode, a first connecting ring is arranged at one end of the protective cover, a second connecting ring is arranged at the other end of the protective cover, a first locking bolt is arranged between the first connecting ring and the fixing ring, and the second connecting ring is connected with the cylinder cover end of an external hydraulic oil cylinder. The surface protection effect of the piston rod for the hydraulic oil cylinder can be improved when the piston rod is used, and dust is prevented from adhering to the piston rod when the piston rod is used.

Description

Technical Field

[0001] This utility model relates to the field of piston rod technology, and more specifically, to a piston rod for a hydraulic cylinder. Background Technology

[0002] The hydraulic piston rod is the core transmission component of a hydraulic cylinder, mainly used to transmit hydraulic thrust or pull. It is typically made of high-strength alloy steel and is widely used in engineering machinery, metallurgical equipment, aerospace, and other fields, requiring high precision, long service life, and stable operation.

[0003] In most existing hydraulic cylinders, the piston rod is directly extended and retracted on the surface of the cylinder during use. During the extension and retraction process, the surface of the piston rod is exposed to the air, and dust and other particles in the air can easily adhere to the surface of the piston rod. Some fine dust particles can also enter the cylinder along with the piston rod, which will affect the operation of the hydraulic cylinder over time. Utility Model Content

[0004] (a) Technical problems to be solved

[0005] To address the problems existing in the prior art, this utility model provides a piston rod for a hydraulic cylinder, thereby solving the technical problem mentioned in the background art of poor surface protection of the piston rod for a hydraulic cylinder during operation.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] A piston rod for a hydraulic cylinder includes a piston rod body. A protective layer is provided on the surface of the piston rod body. This protective layer is formed by laser cladding technology using high-strength alloy steel and nanocomposite materials. The resulting cladding protective layer has advantages such as high hardness, corrosion resistance, and a small heat-affected zone, making it suitable for extreme working conditions. One end of the piston rod body has an inner connecting end, and the other end has an outer connecting end. A fixing ring is provided at the end of the piston rod body near the outer connecting end. A retractable and foldable protective cover is fitted onto the outer side of the piston rod body. One end of the protective cover has a first connecting ring, and the other end has a second connecting ring. A first locking bolt is provided between the first connecting ring and the fixing ring. The second connecting ring is connected to the cylinder head end of an external hydraulic cylinder.

[0009] The present invention is further configured such that the inner connecting end extends inward into the piston rod body and has a buffer groove, and the side wall of the piston rod body is provided with a first pressure relief groove and a second pressure relief groove communicating with the buffer groove. A first pressure relief sealing structure is provided from the buffer groove toward the first pressure relief groove, and a second pressure relief sealing structure is provided from the second pressure relief groove toward the top of the buffer groove. Through the above structure, automatic pressure relief can be achieved when the piston rod body is stuck during operation and the oil pressure inside the cylinder of the hydraulic cylinder is too high, avoiding the situation of hydraulic system component rupture caused by hydraulic system overload, and improving the overall operational safety protection.

[0010] The present invention is further configured such that the first pressure relief sealing structure includes a first sealing plug, the first sealing plug being located at the top of the buffer groove, a connecting post being provided at the bottom end of the first sealing plug, a sealing guide seat being provided at the bottom end of the connecting post corresponding to the first pressure relief groove, a first spring being provided between the bottom end of the sealing guide seat and the bottom end of the buffer groove, and a sealing gasket being provided on the surface of the sealing guide seat. The first sealing plug is used to seal the top of the buffer groove. When the piston rod body is in a stuck state in the extended state, the increased oil pressure inside the external hydraulic cylinder will squeeze the first sealing plug, causing the first spring to contract. This displacement causes the first sealing plug to disengage from the inlet of the buffer groove, allowing the oil to enter the buffer groove for initial buffering and reducing oil pressure. Furthermore, the oil pressure can continue to push the first sealing plug to move. When the first sealing plug moves to the rear of the first pressure relief groove, the first pressure relief groove and the buffer groove can be connected. Thus, the oil entering the buffer groove can flow out through the first pressure relief groove and enter the cylinder of the hydraulic cylinder, located on one side of the piston rod body, thereby achieving pressure relief on the other side. This avoids the situation where the hydraulic system components burst due to overload caused by excessive oil pressure, and provides detection and reaction time.

[0011] The present invention is further configured such that the second pressure relief sealing structure includes a second sealing plug, the second sealing plug being elastically disposed within the second pressure relief groove, and the first sealing plug having an installation groove, the installation groove communicating with the buffer groove and being in the shape of an inverted U, and a sealing block being fitted within the installation groove. With the above structure, when there is too much oil on the side away from the piston rod body, it will squeeze the first sealing plug to move. During this process, the sealing block will be squeezed simultaneously, thus further increasing the squeezing force of the sealing block on the installation groove, thereby improving the sealing effect of the sealing block on the installation groove, ensuring the stable movement of the first sealing plug, and achieving pressure relief in this state.

[0012] The present invention is further configured such that a connecting frame is provided on the connecting column, and the connecting frame is connected to the first sealing plug. At the same time, the connecting frame enables communication between the mounting groove and the buffer groove.

[0013] The present invention is further configured such that a first limiting edge is provided at the top of the buffer groove, the first limiting edge is used to limit the first sealing plug, thereby improving the sealing effect of the first sealing plug on the buffer groove and avoiding oil leakage under normal conditions. A second limiting edge is provided at the outer end of the second pressure relief groove, the second limiting edge is used to limit the second sealing plug, thereby improving the sealing effect of the second sealing plug on the second pressure relief groove.

[0014] This invention is further configured such that a fixing frame is provided inside the second pressure relief groove, and a second spring is provided between the second sealing plug and the fixing frame. Under normal conditions, the second spring provides clamping force to press the second sealing plug tightly into the second pressure relief groove, preventing oil from entering the second pressure relief groove under normal conditions. When the piston rod is stuck inside the cylinder of the external hydraulic cylinder, and the oil is exactly on one side of the piston rod, the increased pressure of the internal oil will squeeze the second sealing plug, causing the second sealing plug to squeeze the second spring. When the squeezing force is greater than the spring force of the second spring, the second spring will generate... Deformation causes the second sealing plug to move, thus disengaging it from the second limiting edge. This allows oil to enter the second pressure relief groove through its inlet and then through the gap between the second sealing plug and the second pressure relief groove into the buffer groove. This initially buffers the oil pressure in the hydraulic cylinder. Furthermore, if this buffering is insufficient, the oil will move along the buffer groove and press against the sealing block located on the first sealing groove, causing the sealing block to disengage from the mounting groove. This allows excess oil to flow outward through the mounting groove to the other side of the hydraulic cylinder barrel, achieving pressure relief from the piston rod direction into the other side of the cylinder.

[0015] The present invention is further configured such that a spring piece is provided on the side wall of the second pressure relief groove, and the bottom end of the spring piece is connected to the second sealing plug. The spring piece enables the second sealing plug to be pressed in the second pressure relief groove under normal conditions, providing another way for the elastically openable installation of the second sealing plug in the second pressure relief groove.

[0016] (III) Beneficial Effects

[0017] Compared with the prior art, this utility model provides a piston rod for a hydraulic cylinder, which has the following characteristics:

[0018] Beneficial effects:

[0019] 1. This utility model includes a piston rod body, and a protective layer is provided on the surface of the piston rod body. The protective layer is formed by laser cladding technology using high-strength alloy steel and nanocomposite materials. The cladding protective layer formed has the advantages of high hardness, corrosion resistance, small heat-affected zone, and suitability for extreme working conditions.

[0020] 2. This utility model has an inner connecting end at one end of the piston rod body and an outer connecting end at the other end. A fixing ring is provided at the end of the piston rod body near the outer connecting end. A protective cover is provided on the outer side of the piston rod body in a retractable and foldable manner. A first connecting ring is provided at one end of the protective cover and a second connecting ring is provided at the other end. A first locking bolt is provided between the first connecting ring and the fixing ring. The second connecting ring is connected to the cylinder head end of the external hydraulic cylinder. In this way, during use, the protective cover can retract and wrap around the outer side of the piston rod body and can retract and extend synchronously with the piston rod, thereby avoiding direct contact between the piston rod and the outside environment, reducing the adhesion of dust and other particles on the piston rod surface, improving the cleanliness of the piston rod during use. In addition, the protective cover in this utility model is easy to replace. It can be easily replaced after the protective cover ages or is worn out.

[0021] 3. This utility model has a buffer groove extending inward from the inner connecting end into the piston rod body. A first pressure relief groove and a second pressure relief groove are provided on the side wall of the piston rod body in communication with the buffer groove. A first pressure relief sealing structure is provided from the buffer groove toward the first pressure relief groove, and a second pressure relief sealing structure is provided from the second pressure relief groove toward the top of the buffer groove. Through the above structure, bidirectional automatic pressure relief can be achieved when the piston rod body is stuck during operation and the oil pressure inside the cylinder of the hydraulic cylinder is too high, avoiding the situation of hydraulic system component bursting due to hydraulic system overload, and improving the overall operational safety protection. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of a piston rod for a hydraulic cylinder according to the present invention;

[0023] Figure 2 This is a cross-sectional view of the installation structure of the protective cover on the piston rod body in this utility model;

[0024] Figure 3 This is a schematic cross-sectional view of a portion of the internal structure of the piston rod in this utility model. Figure 1 ;

[0025] Figure 4 This is a schematic cross-sectional view of a portion of the internal structure of the piston rod in this utility model. Figure 2 ;

[0026] Figure 5 This is a schematic diagram of the structure of the first pressure relief groove in the present invention when it is in the pressure relief state;

[0027] Figure 6 This is a schematic diagram of the structure of the second pressure relief groove in the present invention when it is in the pressure relief state.

[0028] In the diagram: 1. Piston rod body; 2. Protective layer; 3. Inner connecting end; 4. Outer connecting end; 5. Fixing ring; 6. Protective cover; 7. First connecting ring; 8. Second connecting ring; 9. First locking bolt; 10. Buffer groove; 11. First pressure relief groove; 12. Second pressure relief groove; 13. First sealing plug; 14. Connecting column; 15. Sealing guide seat; 16. First spring; 17. Sealing gasket; 18. Second sealing plug; 19. Mounting groove; 20. Sealing block; 21. Connecting frame; 22. First limiting edge; 23. Second limiting edge; 24. Fixing frame; 25. Second spring; 26. Spring. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] In this utility model, unless otherwise stated, the orientations used, such as "up" and "down", usually refer to the direction shown in the accompanying drawings, or to the vertical, perpendicular, or gravitational direction; similarly, for ease of understanding and description, "left" and "right" usually refer to the left and right shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not used to limit this utility model.

[0032] Please see Figures 1-6 A piston rod for a hydraulic cylinder includes a piston rod body 1. A protective layer 2 is provided on the surface of the piston rod body 1. The protective layer 2 is formed by laser cladding technology using high-strength alloy steel and nanocomposite materials. The cladding protective layer 2 has advantages such as high hardness, corrosion resistance, and small heat-affected zone, making it suitable for extreme working conditions. One end of the piston rod body 1 is provided with an inner connecting end 3, and the other end is provided with an outer connecting end 4. A fixing ring 5 is provided at the end of the piston rod body 1 near the outer connecting end 4. A protective cover 6 is provided on the outer side of the piston rod body 1 in a telescopic and foldable manner. One end of the protective cover 6 is provided with a first connecting ring 7, and the other end is provided with a second connecting ring 8. A first locking bolt 9 is provided between the first connecting ring 7 and the fixing ring 5. The second connecting ring 8 is connected to the cylinder head end of an external hydraulic cylinder.

[0033] Furthermore, this utility model provides a buffer groove 10 extending inward from the inner connecting end 3 into the piston rod body 1. A first pressure relief groove 11 and a second pressure relief groove 12 are provided on the side wall of the piston rod body 1 in communication with the buffer groove 10. A first pressure relief sealing structure is provided from the buffer groove 10 toward the first pressure relief groove 11, and a second pressure relief sealing structure is provided from the second pressure relief groove 12 toward the top of the buffer groove 10. Through the above structure, automatic pressure relief can be achieved when the piston rod body 1 is stuck during operation and the oil pressure inside the cylinder of the hydraulic cylinder is too high, avoiding the situation of hydraulic system component rupture caused by hydraulic system overload, and improving the overall operational safety protection.

[0034] Please see Figures 1-6 As one embodiment of the first pressure relief sealing structure: the first pressure relief sealing structure includes a first sealing plug 13, which is located at the top of the buffer groove 10. A connecting post 14 is provided at the bottom end of the first sealing plug 13, and a sealing guide seat 15 is provided at the bottom end of the connecting post 14 corresponding to the first pressure relief groove 11. A first spring 16 is provided between the bottom end of the sealing guide seat 15 and the bottom end of the buffer groove 10. A sealing gasket 17 is provided on the surface of the sealing guide seat 15. The first sealing plug 13 is used to seal the top of the buffer groove 10. When the piston rod body 1 is in the extended and stuck state, the increased oil pressure in the cylinder of the external hydraulic cylinder will squeeze the first sealing plug 13, causing the first spring to... 16. Contraction causes displacement, displacing the first sealing plug 13 from the inlet of the buffer groove 10, allowing oil to enter the buffer groove 10 for initial buffering and reducing oil pressure. Further, the oil pressure can continue to push the first sealing plug 13 to move. When the first sealing plug 13 moves to the rear of the first pressure relief groove 11, the first pressure relief groove 11 and the buffer groove 10 can be connected. Thus, the oil entering the buffer groove 10 can flow out through the first pressure relief groove 11 and enter the cylinder of the hydraulic cylinder, which is located on one side of the piston rod body 1, thereby achieving pressure relief on the other side. This avoids the situation where hydraulic system components burst due to overload caused by excessive oil pressure, and provides detection and reaction time.

[0035] Please see Figures 1-6As one embodiment of the second pressure relief sealing structure: the second pressure relief sealing structure includes a second sealing plug 18, which is elastically disposed in the second pressure relief groove 12. The first sealing plug 13 has an installation groove 19, which is connected to the buffer groove 10 and is in the shape of an inverted U. A sealing block 20 is disposed in the installation groove 19. With the above structure, when there is too much oil on the side away from the piston rod body 1, it will squeeze the first sealing plug 13 to move. During this process, the sealing block 20 will be squeezed simultaneously. In this way, the squeezing force of the sealing block 20 on the installation groove 19 can be further increased, thereby improving the sealing effect of the sealing block 20 on the installation groove 19, ensuring the stable movement of the first sealing plug 13, and realizing pressure relief in this state.

[0036] Furthermore, a connecting bracket 21 is provided on the connecting column 14, and the connecting bracket 21 is connected to the first sealing plug 13. At the same time, the connecting bracket 21 enables communication between the mounting groove 19 and the buffer groove 10.

[0037] This invention provides a first limiting edge 22 at the top of the buffer groove 10, which is used to limit the first sealing plug 13. This improves the sealing effect of the first sealing plug 13 on the buffer groove 10 and avoids oil leakage under normal conditions. A second limiting edge 23 is provided at the outer end of the second pressure relief groove 12, which is used to limit the second sealing plug 18. This improves the sealing effect of the second sealing plug 18 on the second pressure relief groove 12.

[0038] Please see Figures 1-6As one embodiment of the second sealing plug 18: a fixing frame 24 is provided inside the second pressure relief groove 12, and a second spring 25 is provided between the second sealing plug 18 and the fixing frame 24. Under normal conditions, under the action of the second spring 25, the second sealing plug 18 is pressed and fixed at the second pressure relief groove 12, providing a clamping force to prevent oil from entering the second pressure relief groove 12 under normal conditions. When the piston rod is stuck in the cylinder of the external hydraulic cylinder, and the oil is exactly on one side of the piston rod, the increased pressure of the internal oil will squeeze the second sealing plug 18, causing the second sealing plug 18 to squeeze the second spring 25. When the squeezing force is greater than the elastic force of the second spring 25, the second spring 25 will... The deformation of part 5 causes the second sealing plug 18 to move, thereby disengaging from the second limiting edge 23. This allows the oil to enter the second pressure relief groove 12 through the inlet and then enter the buffer groove 10 through the gap between the second sealing plug 18 and the second pressure relief groove 12. This initially buffers the oil pressure in the hydraulic cylinder. Furthermore, if this buffering is insufficient, the oil will move along the buffer groove 10 and squeeze the sealing block 20 located on the first sealing groove, causing the sealing block 20 to disengage from the mounting groove 19. This allows excess oil to flow outward through the mounting groove 19 to the other side of the hydraulic cylinder barrel, achieving pressure relief from the piston rod direction to the other side of the cylinder.

[0039] Please see Figures 1-6 As one embodiment of the second sealing plug 18: a spring piece 26 is provided on the side wall of the second pressure relief groove 12. The bottom end of the spring piece 26 is connected to the second sealing plug 18. The spring piece 26 enables the second sealing plug 18 to be pressed in the second pressure relief groove 12 in the normal state, providing another way for the second sealing plug 18 to be elastically openable installed in the second pressure relief groove 12.

[0040] In summary:

[0041] This utility model includes a piston rod body 1, and a protective layer 2 is provided on the surface of the piston rod body 1. The protective layer 2 is formed by laser cladding technology using high-strength alloy steel and nanocomposite materials. The cladding protective layer 2 formed has the advantages of high hardness, corrosion resistance, small heat-affected zone, and suitability for extreme working conditions.

[0042] This invention features an inner connecting end 3 at one end of the piston rod body 1 and an outer connecting end 4 at the other end. A fixing ring 5 is provided at the end of the piston rod body 1 near the outer connecting end 4. A protective cover 6 is provided on the outer side of the piston rod body 1 in a telescopic and foldable manner. A first connecting ring 7 is provided at one end of the protective cover 6, and a second connecting ring 8 is provided at the other end. A first locking bolt 9 is provided between the first connecting ring 7 and the fixing ring 5. The second connecting ring 8 is connected to the cylinder head end of the external hydraulic cylinder. In this way, during use, the protective cover 6 can telescopically wrap around the outer side of the piston rod body 1 and can extend and retract synchronously with the piston rod, thereby preventing the piston rod from directly contacting the outside world, reducing the adhesion of dust and other particles on the piston rod surface, improving the cleanliness of the piston rod during use, and the protective cover 6 in this invention is easy to replace. It can be easily replaced after the protective cover 6 ages or is worn out.

[0043] This utility model has a buffer groove 10 extending inward from the inner connecting end 3 into the piston rod body 1. A first pressure relief groove 11 and a second pressure relief groove 12 are provided on the side wall of the piston rod body 1 in communication with the buffer groove 10. A first pressure relief sealing structure is provided from the buffer groove 10 toward the first pressure relief groove 11, and a second pressure relief sealing structure is provided from the second pressure relief groove 12 toward the top of the buffer groove 10. Through the above structure, bidirectional automatic pressure relief can be achieved when the piston rod body 1 is stuck during operation and the internal oil pressure of the hydraulic cylinder is too high, so as to avoid the hydraulic system components from bursting due to hydraulic system overload and improve the overall operation safety protection.

[0044] In this invention, the first spring 16 and the second spring 25 are both existing mature products. The appropriate spring coefficient can be selected according to the size of the hydraulic cylinder model. This can be achieved with existing technology. In addition, the first spring 16 and the second spring 25 in this invention are for emergency use and there is no repeated compression. In this invention, the elastic force of the first spring 16 and the second spring 25 under normal conditions is greater than the hydraulic pressure value of the oil in the hydraulic cylinder under normal operating conditions, ensuring the stable sealing of the first sealing plug 13 and the second sealing plug 18.

[0045] In all the solutions mentioned above, the connection between two components can be selected according to the actual situation, such as welding, bolt and nut connection, bolt or screw connection, or other known connection methods, which will not be elaborated here. For all the fixed connections mentioned above, welding is preferred. Although the embodiments of this utility model have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of this utility model. The scope of this utility model is defined by the appended claims and their equivalents.

[0046] In all the solutions mentioned above, those involving the operation of electrical components, unless otherwise specified, are controlled by a controller. Since the devices matched with the controllers are common devices, their control principles and circuit connections are existing, well-known, and mature technologies, and their specific circuit structures will not be described in detail here.

[0047] Of all the solutions mentioned above, those involving motors can be combined with reducers if necessary. The connection structure and working principle between the motor and the reducer are existing known technologies, and this utility model will not elaborate on them.

[0048] If any of the technical solutions mentioned above involve a synchronous belt drive structure, and there is no specific structure, they are all existing technologies involving the combination of synchronous belt and synchronous pulley. The connection between the synchronous belt and the shaft structure is a known technology and will not be elaborated upon in this utility model.

[0049] Of all the solutions mentioned above, those involving the connection between solar panels and batteries can be equipped with essential accessories such as inverters, battery charging controllers, cables, fuses, and brackets. Their control principles and circuit connections are all existing, well-known, and mature technologies, and their specific circuit structures will not be elaborated here.

Claims

1. A piston rod for hydraulic cylinders, comprising a piston rod body (1), characterized in that: The surface of the piston rod body (1) is provided with a protective layer (2), one end of the piston rod body (1) is provided with an inner connecting end (3), and the other end is provided with an outer connecting end (4), one end of the piston rod body (1) close to the outer connecting end (4) is provided with a fixed ring (5), the outer side of the piston rod body (1) is telescopic folded and provided with a protective cover (6), one end of the protective cover (6) is provided with a first connecting ring (7), and the other end is provided with a second connecting ring (8), the first connecting ring (7) and the fixed ring (5) are provided with a first locking bolt (9), and the second connecting ring (8) is connected with the cylinder cover end of the external hydraulic oil cylinder.

2. The piston rod for hydraulic cylinders according to claim 1, characterized in that The inner connecting end (3) extends inwardly to the inside of the piston rod body (1) and is provided with a buffer groove (10), the side wall of the piston rod body (1) is provided with a first pressure relief groove (11) and a second pressure relief groove (12) in communication with the buffer groove (10), the first pressure relief groove (11) is provided with a first pressure relief plugging structure from the buffer groove (10), and the second pressure relief groove (12) is provided with a second pressure relief plugging structure towards the top end of the buffer groove (10).

3. The piston rod for hydraulic cylinders according to claim 2, characterized in that The first pressure relief plugging structure comprises a first sealing plug (13), the first sealing plug (13) is located at the top end of the buffer groove (10), the bottom end of the first sealing plug (13) is provided with a connecting column (14), the bottom end of the connecting column (14) is provided with a sealing guide seat (15) corresponding to the first pressure relief groove (11), the bottom end of the sealing guide seat (15) and the bottom end of the buffer groove (10) are provided with a first spring (16), and the surface of the sealing guide seat (15) is provided with a sealing pad (17).

4. The piston rod for hydraulic cylinders according to claim 3, characterized in that The second pressure relief plugging structure comprises a second sealing plug (18), the second sealing plug (18) is elastically arranged in the second pressure relief groove (12), the first sealing plug (13) is provided with a mounting groove (19), the mounting groove (19) is in communication with the buffer groove (10), and the mounting groove (19) is in the shape of an inverted convex character, and the mounting groove (19) is matched with a sealing block (20).

5. The piston rod for hydraulic cylinders according to claim 4, characterized in that The connecting column (14) is provided with a connecting frame (21), and the first sealing plug (13) is connected through the connecting frame (21), and the communication between the mounting groove (19) and the buffer groove (10) is realized through the connecting frame (21).

6. The piston rod for hydraulic cylinders according to claim 4, characterized in that: The top end of the buffer groove (10) is provided with a first limiting edge (22), the first limiting edge (22) is used for limiting the first sealing plug (13), and the outer end of the second pressure relief groove (12) is provided with a second limiting edge (23), the second limiting edge (23) is used for limiting the second sealing plug (18).

7. The piston rod for hydraulic cylinders according to claim 4, characterized in that: The second pressure relief groove (12) is provided with a fixed frame (24), and the second sealing plug (18) and the fixed frame (24) are provided with a second spring (25).

8. The piston rod for hydraulic cylinders according to claim 4, characterized in that: The side wall of the second pressure relief groove (12) is provided with a spring piece (26), and the bottom end of the spring piece (26) is connected with the second sealing plug (18).

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