Thin hydraulic oil cylinder with annular groove formed in oil inlet

Abstract

The utility model relates to a thin hydraulic oil cylinder with an oil inlet provided with an annular groove, and belongs to the technical field of hydraulic dies. On the basis of the body, the front cover, the rear cover, the piston and the piston rod, the assembly inside the oil cylinder is reinforced by improving the hole position arrangement of the body and the structures of the inner hole and the screw hole, and the thin oil cylinder with the annular oil inlet is formed by arranging the partial step-shaped structures of the front cover, the rear cover and the piston and the annular oil seal groove structure. When oil enters the rear oil inlet, the piston rod is in an extending state; when oil enters from the front oil inlet, the piston rod is in a retracted state and is matched with the copper gasket, the set screw, the O-shaped ring, the back-up ring, the wear-resistant ring and the like, so that the sealing performance of the whole structure and the supporting capacity of parts are improved, the machining cost is low, measurement is convenient, the edge cutting phenomenon can be effectively avoided when the O-shaped ring is assembled, and the sealing performance of the oil cylinder is good.

Description

Technical Field

[0001] The utility model relates to a thin hydraulic cylinder with an annular groove processed at an oil inlet, belonging to the technical field of hydraulic molds. Background Technique

[0002] There are various types of hydraulic cylinders. Among them, thin hydraulic cylinders are widely used in the mold industry due to their small volume. Therefore, thin hydraulic cylinders with different structures have emerged as the times require. Generally, a forward oil inlet and a rear oil inlet are processed on the cylinder body of the thin hydraulic cylinder. According to different thread angles, the forward and rear oil inlets can be divided into American standard threads, British standard threads, metric threads, etc. However, no matter which thread type, an oil pressure joint and a hydraulic oil pipe must be installed on the cylinder body to enable the thin hydraulic cylinder to perform forward and backward movements. However, the oil pressure joint has a certain diameter and height. For the mold industry with limited space, there is no longer enough space to accommodate the oil pressure joint. Moreover, in the absence of the oil pressure joint, the thin hydraulic cylinder will not be able to intake oil and operate normally.

[0003] Therefore, currently, most use oil circuit plate oil inlet to avoid the problem of limited installation space. Specifically, by opening an oil circuit on the oil circuit plate and installing an oil pressure joint, the thin hydraulic cylinder is supplied with oil. Between the thin hydraulic cylinder and the oil circuit plate, in order to prevent oil leakage, an O-ring is generally installed on the cylinder body of the thin hydraulic cylinder, and the space for accommodating the O-ring is a dovetail groove with a certain depth. However, since the dovetail groove is wider inside and narrower outside, when the O-ring is placed into the dovetail groove, it is easy to cause the "edge cutting" phenomenon of the O-ring, resulting in oil leakage of the thin hydraulic cylinder.

[0004] In addition, as an important index of sealing performance, the "compression ratio" is also a factor that has to be considered. An excessive or too small "compression ratio" will cause oil leakage of the thin hydraulic cylinder, affecting product quality. Moreover, the oil leakage phenomenon will cause the customer's machine to stop production, resulting in huge economic losses. In addition, when processing the dovetail groove, customized processing tools need to be ordered. The outer diameter, inner diameter, depth and angle of the dovetail groove must be extremely precise. The processing technology is complex, the processing time is long, the cost is high and it is not conducive to dimension measurement.

[0005] Currently, although there is a thin hydraulic cylinder shown in, for example, CN217271137U in the prior art, and this cylinder is processed with a tapered groove, it still has the following problems:

[0006] 1. The processing requirements are high, and customized tools are needed for processing, resulting in increased costs; 2. The structure of the dovetail groove determines that there is a certain sharp angle at its outer end, so there is a risk of "edge cutting" when the O-ring is placed in the dovetail groove, which will cause oil leakage of the hydraulic cylinder; 3. The dovetail groove will cause an increase in the "filling rate". An excessive filling rate will cause the O-ring to not be fully compressed, and then there is a risk of oil leakage in the cylinder. Summary of the Utility Model

[0007] To solve the above problems, the present utility model provides a thin hydraulic cylinder with an annular groove processed at the oil inlet, comprising:

[0008] A body, the body is a cylindrical structure with a rectangular cross-section, the axial two ends of the body respectively have a body left end face and a body right end face, the body left end face and the body right end face are respectively provided with a first internal threaded hole and a second internal threaded hole, and the first internal threaded hole and the second internal threaded hole are penetrated and communicated through the inner hole of the body; a forward oil inlet and a backward oil inlet communicating with the inner hole of the body are arranged on the radial side surface of the body; a keyway is milled on the radial side surface of the body;

[0009] A front cover, the front cover has a front cover first stepped shaft, a front cover second stepped shaft and a front cover third stepped shaft connected in sequence from left to right, the front cover first stepped shaft and the front cover second stepped shaft are respectively matched with the first internal threaded hole and the inner hole of the body, and the axial two ends of the front cover respectively have a front cover left end face and a front cover right end face;

[0010] A rear cover, the rear cover has a rear cover first stepped shaft and a rear cover second stepped shaft connected in sequence from right to left, the rear cover first stepped shaft and the rear cover second stepped shaft are respectively matched with the second internal threaded hole and the inner hole of the body, and the axial two ends of the rear cover respectively have a rear cover left end face and a rear cover right end face;

[0011] A piston, which is fitted in the inner hole of the body and is located between the front cover and the rear cover; and

[0012] A piston rod, which is penetrated and fitted in the front cover and the piston.

[0013] Further, a first stop screw hole, a second stop screw hole and a plurality of mounting and fixing holes are further arranged on the radial side surface of the body, the first stop screw hole is communicated with the first internal threaded hole, the second stop screw hole is communicated with the second internal threaded hole, and copper gaskets and stop screws are arranged in the holes of the first stop screw hole and the second stop screw hole. Since the thin cylinder will cause the thread connection between the front cover, the rear cover and the body to become loose in the occasions of impact, vibration or variable load, seriously affecting the use safety of the thin cylinder, the copper gasket is arranged to be deformed under the extrusion of the stop screw, which can reinforce the thread fit and enhance the safety of the cylinder.

[0014] Furthermore, a first relief groove is provided between the first internal threaded hole and the inner hole of the body, and a second relief groove is provided between the second internal threaded hole and the inner hole of the body. There is a gap between the first check screw hole and the left end face of the body, and between the second check screw hole and the right end face of the body, thereby preventing interference between the copper gasket, the check screw and the first and second relief grooves, increasing the contact area with the front cover, and improving the safety of the oil cylinder.

[0015] Furthermore, the two side ports of the inner hole of the body have inclined end faces that are inclined outward by 25 degrees, which can prevent the piston seal and the wear-resistant ring from being scratched; a first plug hole and a second plug hole are respectively provided on the radial side face and the right end face of the body, and both the first plug hole and the second plug hole communicate with the rear oil inlet and the inner hole of the body.

[0016] Furthermore, the diameters of the first stepped shaft, the second stepped shaft, and the third stepped shaft of the front cover decrease in sequence. The second stepped shaft of the front cover has an oil seal groove for the front cover; inside the front cover, there are a first hollow cavity, a second hollow cavity, and a third hollow cavity connected in sequence from left to right. A spiral oil guiding groove is provided in the third hollow cavity; a cylindrical front cover wrench hole is provided on the left end face of the front cover.

[0017] Furthermore, the second stepped shaft of the rear cover has an oil seal groove for the rear cover; a clearance groove is provided on the left end face of the rear cover, and the depth of the clearance groove can be 0.5 - 1 mm. The purpose of setting the clearance groove is that due to the viscosity of the hydraulic oil, the plane of the rear cover and the piston are mutually attached together, resulting in difficulty in starting the oil cylinder; by machining the clearance groove, the contact area between the rear cover and the piston is reduced, so that the oil cylinder can start smoothly and perform corresponding actions; a lifting ring hole and a cylindrical rear cover wrench hole are provided on the right end face of the rear cover.

[0018] Furthermore, the piston internally has a through cylindrical piston hole, and the diameter of the piston hole decreases from left to right. At least a part of the piston hole has internal threads; a piston oil seal groove is provided on the side of the piston, and a first wear-resistant ring groove and a second wear-resistant ring groove are respectively provided on the left and right sides of the piston oil seal groove. The width of the first wear-resistant ring groove is greater than the width of the second wear-resistant ring groove. When space permits, the width of the wear-resistant ring is increased, which can improve the support performance of the thin oil cylinder; chamfers are provided at both ends of the piston edge. When the front / rear oil port of the thin hydraulic oil cylinder admits oil, the chamfers can prevent the oil inlet from being blocked, ensuring the smoothness of the front / rear oil port oil inlet passage.

[0019] The front cover oil seal groove and the rear cover oil seal groove are both fitted with an O-ring and a back-up ring, which can play a supporting role to prevent the O-ring from being extruded into the gap between the front / rear cover and the body due to excessive pressure in the hydraulic system, thus preventing damage to the O-ring. The piston oil seal groove is fitted with a piston seal sleeve, which enhances the sealing effect between the piston and the body and extends the service life of the piston. The first wear-resistant ring groove and the second wear-resistant ring groove are both provided with wear-resistant rings. The wear-resistant rings can not only prevent scratches between the piston and the body, but also enable the piston rod to resist lateral forces.

[0020] Further, the piston rod has a first piston shaft, a second piston shaft, and a third piston shaft connected in sequence from left to right. The second piston shaft is allowed to cooperate with the second hollow cavity and the third hollow cavity of the front cover. The third piston shaft has an external thread that mates with the internal thread of the piston hole. Among them, the first piston shaft can be assembled with a piston rod cap to fix the piston rod in place and prevent unnecessary movement or detachment during operation.

[0021] Further, the second piston shaft is provided with a force application surface and a piston shaft oil seal groove. It is allowed to tighten the fit between the third piston shaft and the piston hole by applying a socket wrench to the force application surface. The piston shaft oil seal groove is fitted with an O-ring. It is allowed for the external thread of the third piston shaft to cooperate with a check screw.

[0022] Advantages of the present utility model:

[0023] Based on the body, front cover, rear cover, piston, and piston rod, the present utility model strengthens the assembly inside the oil cylinder by improving the hole position settings and the structures of the inner hole and screw holes of the body. By setting partial stepped structures of the front cover, rear cover, and piston and annular oil seal groove structures, a thin oil cylinder with an annular oil inlet is formed. When the rear oil inlet is supplied with oil, the piston rod is in the extended state; when the front oil inlet is supplied with oil, the piston rod is in the retracted state. Together with copper gaskets, check screws, O-rings, back-up rings, wear-resistant rings, etc., the overall structure's sealing performance and component support capacity are improved. The processing cost is low, the measurement is convenient, and the "edge cutting" phenomenon can be effectively avoided when assembling the O-ring. The oil cylinder has good sealing performance. Additionally, a keyway with a certain width and completely penetrating can be machined on the radial side surface of the body. The keyway and the installation machine at the customer's place adopt a concave-convex fit, which can effectively resist the tipping moment generated during the actuation of the thin oil cylinder and ensure the safety and smoothness during the actuation of the thin oil cylinder. Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the overall structure assembly in one embodiment of the present utility model;

[0025] Figure 2The structural sectional view of the main view of the body in an embodiment of the present utility model;

[0026] Figure 3 The structural schematic diagram of the front cover in an embodiment of the present utility model;

[0027] Figure 4 The structural schematic diagram of the piston in an embodiment of the present utility model;

[0028] Figure 5 The structural schematic diagram of the rear cover in an embodiment of the present utility model.

[0029] Figure 6 The top view of the body in an embodiment of the present utility model.

[0030] Figure 7 The structural schematic diagram of the piston rod in an embodiment of the present utility model.

[0031] In the figure: 1, front cover; 2, rear cover; 3, piston; 4, piston rod; 5, piston rod shaft cap; 6, copper gasket; 7, set screw; 8, body;

[0032] 11, the first stepped shaft of the front cover; 12, the second stepped shaft of the front cover; 13, the third stepped shaft of the front cover; 14, the first hollow cavity of the front cover; 15, the second hollow cavity of the front cover; 16, the third hollow cavity of the front cover; 17, oil guiding groove; 18, oil seal groove of the front cover;

[0033] 21, the first stepped shaft of the rear cover; 22, the second stepped shaft of the rear cover; 23, oil seal groove of the rear cover; 24, clearance groove;

[0034] 31, the first wear-resistant ring groove; 32, the second wear-resistant ring groove; 33, oil seal groove of the piston; 34, piston hole; 41, the first piston shaft; 42, the second piston shaft; 43, the third piston shaft; 44, oil seal groove of the piston shaft; 45, force application surface;

[0035] 81, the first internal thread hole; 82, the second internal thread hole; 83, inner hole of the body; 84, forward oil inlet; 85, backward oil inlet; 86, the first set screw hole; 87, the second set screw hole; 88, installation and fixing hole; 851, the first plug hole; 852, the second plug hole; A, the first relief groove; B, the second relief groove; C, wrench hole of the front cover; D, lifting ring hole; E, wrench hole of the rear cover. Specific embodiments

[0036] The technical solution of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0037] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions.

[0038] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0039] Embodiment 1

[0040] As Figures 1-7 shown, the present utility model provides a thin hydraulic cylinder with an annular groove processed at the oil inlet, including:

[0041] A body 8, the body 8 is a cylindrical structure with a rectangular cross-section. The axial ends of the body 8 respectively have a left end face of the body and a right end face of the body. The left end face of the body and the right end face of the body are respectively provided with a first internal threaded hole 81 and a second internal threaded hole 82. The first internal threaded hole 81 and the second internal threaded hole 82 are connected through the inner hole 83 of the body; a forward oil inlet 84 and a backward oil inlet 85 communicating with the inner hole 83 of the body are arranged on the radial side of the body 8; a keyway is milled on the radial side of the body 8.

[0042] Front cover 1, the front cover 1 has a front cover first stepped shaft 11, a front cover second stepped shaft 12, and a front cover third stepped shaft 13 that are connected in sequence from left to right. The front cover first stepped shaft 11 and the front cover second stepped shaft 12 are respectively fitted with a first internal threaded hole 81 and an inner body hole 83. Axial ends of the front cover 1 respectively have a front cover left end face and a front cover right end face;

[0043] Rear cover 2, the rear cover 2 has a rear cover first stepped shaft 21 and a rear cover second stepped shaft 22 that are connected in sequence from right to left. The rear cover first stepped shaft 21 and the rear cover second stepped shaft 22 are respectively fitted with a second internal threaded hole 82 and an inner body hole 83. Axial ends of the rear cover 2 respectively have a rear cover left end face and a rear cover right end face;

[0044] Piston 3, fitted in the inner body hole 83 and located between the front cover 1 and the rear cover 2; and

[0045] Piston rod 4, penetrating and fitted in the front cover 1 and the piston 3.

[0046] Furthermore, a first check screw hole 86, a second check screw hole 87, and a plurality of mounting and fixing holes 88 are further provided on a radial side surface of the body 8. The first check screw hole 86 communicates with the first internal threaded hole 81, the second check screw hole 87 communicates with the second internal threaded hole 82, and copper gaskets 6 and check screws 7 are provided in the holes of the first check screw hole 86 and the second check screw hole 87. Since in the case of impact, vibration, or variable load of the thin cylinder, loosening of the threaded connection between the front cover 1, the rear cover 2, and the body 8 will occur, seriously affecting the use safety of the thin cylinder. Therefore, it is provided that the copper gasket 6 is deformed under the extrusion of the check screw 7, which can reinforce the threaded fit and enhance the safety of the cylinder.

[0047] Furthermore, a first relief groove A and a second relief groove B are respectively provided between the first internal threaded hole 81 and the inner body hole 83, and between the second internal threaded hole 82 and the inner body hole 83. There are intervals between the first check screw hole 86 and the left end face of the body, and between the second check screw hole 87 and the right end face of the body, so as to avoid interference between the copper gasket 6, the check screw 7 and the first relief groove A, the second relief groove B, increase the contact area with the front cover 1, and improve the safety of the cylinder.

[0048] Furthermore, both side ports of the inner body hole 83 have inclined end faces that are inclined 25 degrees outward, which can prevent the piston seal and the wear-resistant ring from being scratched; a first plug hole 851 and a second plug hole 852 are respectively provided on a radial side surface of the body and the right end face of the body. The first plug hole 851 and the second plug hole 852 communicate with the rear oil inlet 85 and the inner body hole 83.

[0049] Further, the diameters of the first front cover stepped shaft 11, the second front cover stepped shaft 12, and the third front cover stepped shaft 13 decrease in sequence. The second front cover stepped shaft 12 has a front cover oil seal groove 18. Inside the front cover 1, there are a first front cover hollow cavity 14, a second front cover hollow cavity 15, and a third front cover hollow cavity 16 connected in sequence from left to right. The third hollow cavity 16 is provided with a spiral oil guiding groove 17. By designing the oil guiding groove 17, hydraulic oil can quickly penetrate into the third front cover hollow cavity 16. After the hydraulic oil quickly opens the U-shaped lip of the piston seal, it plays a sealing role, which can not only effectively prevent oil leakage but also greatly improve the sealing performance of the thin hydraulic cylinder.

[0050] A cylindrical front cover wrench hole C is provided on the left end face of the front cover 1. The front cover 1 and the body 8 can be locked through thread fitting by a special fixture, enhancing stability.

[0051] Further, the second rear cover stepped shaft 22 has a rear cover oil seal groove 23. An avoidance groove 24 is provided on the left end face of the rear cover. The depth of the avoidance groove 24 can be 0.5 - 1 mm. The purpose of setting the avoidance groove 24 is that due to the viscosity of the hydraulic oil, the rear cover 2 and the plane of the piston 3 are in mutual contact, resulting in difficult start-up of the oil cylinder. By machining the avoidance groove 24, the contact area between the rear cover 2 and the piston 3 is reduced, so that the oil cylinder can start smoothly and perform corresponding actions.

[0052] A lifting ring hole D and a cylindrical rear cover wrench hole E are provided on the right end face of the rear cover 2. The function of the rear cover wrench hole E is that the rear cover 2 and the body 8 can be locked through thread fitting by a special fixture. The lifting ring hole D is processed at the center of the right end face of the rear cover 2. After the whole thin oil cylinder is assembled, the lifting ring is locked into the lifting ring hole, which can not only quickly complete the loading, unloading, and transportation of the oil cylinder but also effectively prevent the oil cylinder from falling and tilting to reduce the accident risk.

[0053] Among them, the specifications of the lifting ring hole D are usually represented by the thread diameter. The larger the diameter of the lifting ring hole D, the stronger its bearing capacity. The specific dimensions and bearing capacities of different specifications of the lifting ring hole D depend on different specifications of the lifting rings. The relationship between some lifting ring specifications and their bearing capacities is shown in Table 8.

[0054] Table 8

[0055]

[0056] Further, a through cylindrical piston hole 34 is formed inside the piston 3, the diameter of the piston hole 34 decreasing from left to right, and at least a part of the piston hole 34 has internal threads; on the side surface of the piston 3, there is a piston oil seal groove 33, and on the left and right sides of the piston oil seal groove 33, there are respectively a first wear-resistant ring groove 31 and a second wear-resistant ring groove 32. The width of the first wear-resistant ring groove 31 is greater than that of the second wear-resistant ring groove 32. When space permits, the width of the wear-resistant ring is increased, which can improve the support performance of the thin cylinder. Chamfers are provided at both ends of the piston. When the front / rear oil ports of the thin hydraulic cylinder are feeding oil, the chamfers can prevent the oil inlet from being blocked and ensure the smoothness of the oil inlet passage of the front / rear oil ports.

[0057] The front cover oil seal groove 18 and the rear cover oil seal groove 23 are both fitted with an O-ring and a back-up ring, which can play a supporting role to prevent the O-ring from being extruded into the gap between the front / rear cover and the body due to excessive pressure in the hydraulic system, thus preventing damage to the O-ring; the piston oil seal groove 33 is fitted with a piston seal sleeve, which increases the sealing effect between the piston and the body and extends the service life of the piston; wear-resistant rings are provided in both the first wear-resistant ring groove 31 and the second wear-resistant ring groove 32. The wear-resistant rings can not only prevent scratches between the piston 3 and the body 8, but also enable the piston rod 4 to resist lateral forces.

[0058] Further, the piston rod 4 has a first piston shaft 41, a second piston shaft 42, and a third piston shaft 43 connected in sequence from left to right. The second piston shaft 42 is allowed to cooperate with the second hollow cavity 15 and the third hollow cavity 16 of the front cover, and the third piston shaft 43 has external threads that cooperate with the internal threads of the piston hole 34. Among them, the first piston shaft 41 can be assembled with the piston rod shaft cap 5 to fix the piston rod 4 in place and prevent unnecessary movement or detachment during operation.

[0059] Further, the second piston shaft 42 is provided with a force application surface 45 and a piston shaft oil seal groove 44. It is allowed to tighten the fit between the third piston shaft 43 and the piston hole 34 by applying a movable wrench to the force application surface 45, and the piston shaft oil seal groove 44 is fitted with an O-ring; it is allowed for the external threads of the third piston shaft 43 to cooperate with a check screw 7.

[0060] When the hydraulic system feeds oil through the forward oil port 84 of the body 8, the piston 3 drives the piston rod 4 to move backward (to the right in the figure). When the piston 3 moves to the end (against the rear cover 2), the chamfered part at the right end face of the piston 3 and the inner hole 83 of the body form a cavity. When the electromagnetic valve changes direction, the hydraulic oil enters the cavity from the rear oil port 85 through the first choke hole 851, so that the hydraulic oil pushes the piston 3 forward, thus realizing the reciprocating motion of the thin cylinder. The second choke hole 852 acts as a "bridge" to connect the rear oil port 85 and the first choke hole 851, so that the oil can be transported from the rear oil port to the inside of the thin cylinder body. At the same time, the distance between the second choke hole 852 and the second internal threaded hole 82 ensures the safety factor of the threaded connection.

[0061] Embodiment 2

[0062] Since the front cover oil seal groove 18, the rear cover oil seal groove 23, and the piston shaft oil seal groove 44 are all annular grooves, and the dimensional parameters of these annular grooves all include the inner diameter (￠A), the outer diameter (￠B), and the depth (t), the sealing performance of the thin cylinder is closely related to them.

[0063] At the same time, the "compression rate" and "filling rate" of the O-ring are also two important indicators of the sealing performance of the thin cylinder. If the "compression rate" is too large, the O-ring is prone to compression cracking; if the "compression rate" is too small, leakage may occur.

[0064] Therefore, in this embodiment, the inner diameter (￠A), the outer diameter (￠B), the depth (t) of different annular grooves and their corresponding O-ring compression rates and filling rates are studied, as shown in Table 9.

[0065] Table 9

[0066]

[0067] It can be seen that when the inner diameter (￠A), the outer diameter (￠B), and the depth (t) conform to the dimensions in Table 9, the "compression rate" and the "filling rate" both conform to the set values of the O-ring. The O-ring can not only seal the thin cylinder, but also will not cause compression cracking and seal leakage.

[0068] Although the present utility model has been disclosed above with preferred embodiments, it is not intended to limit the present utility model. Anyone familiar with this technology can make various modifications and decorations without departing from the spirit and scope of the present utility model. Therefore, the protection scope of the present utility model should be defined by the claims.

Claims

1. A thin hydraulic cylinder with an annular groove machined at the oil inlet, characterized in that, Comprising: A body, the body being a cylindrical structure with a rectangular cross-section. The axial two ends of the body respectively have a left body end face and a right body end face. A first internal thread hole and a second internal thread hole are respectively provided on the left body end face and the right body end face. The first internal thread hole and the second internal thread hole are penetrated and communicated through the inner hole of the body. An advance oil port and a retreat oil port communicating with the inner hole of the body are provided on the radial side surface of the body. A keyway is milled on the radial side surface of the body. A front cover, the front cover having a first front cover stepped shaft, a second front cover stepped shaft, and a third front cover stepped shaft connected in sequence from left to right. The first front cover stepped shaft and the second front cover stepped shaft are respectively fitted with the first internal thread hole and the inner hole of the body. The axial two ends of the front cover respectively have a left front cover end face and a right front cover end face. A rear cover, the rear cover having a first rear cover stepped shaft and a second rear cover stepped shaft connected in sequence from right to left. The first rear cover stepped shaft and the second rear cover stepped shaft are respectively fitted with the second internal thread hole and the inner hole of the body. The axial two ends of the rear cover respectively have a left rear cover end face and a right rear cover end face. A piston, fitted in the inner hole of the body and located between the front cover and the rear cover; and A piston rod, penetrating and fitted in the front cover and the piston.

2. A thin hydraulic cylinder with an annular groove machined at the oil inlet, according to claim 1, characterized in that, A first stop screw hole, a second stop screw hole, and a plurality of mounting and fixing holes are further provided on the radial side surface of the body. The first stop screw hole communicates with the first internal thread hole, and the second stop screw hole communicates with the second internal thread hole. Copper gaskets and stop screws are provided in the holes of the first stop screw hole and the second stop screw hole.

3. The thin hydraulic cylinder with an annular groove machined at the oil inlet according to claim 2, wherein, A first relief groove and a second relief groove are respectively provided between the first internal thread hole and the inner hole of the body, and between the second internal thread hole and the inner hole of the body. There are intervals between the first stop screw hole and the left body end face, and between the second stop screw hole and the right body end face.

4. A thin hydraulic cylinder with an annular groove machined at the oil inlet, characterized in that, The two side ports of the inner hole of the body have inclined end faces inclined 25 degrees outward. A first plug hole and a second plug hole are respectively provided on the radial side surface of the body and the right body end face. The first plug hole and the second plug hole are both communicated with the retreat oil port and the inner hole of the body.

5. A thin hydraulic cylinder with an annular groove machined at the oil inlet, characterized in that, The diameters of the first front cover stepped shaft, the second front cover stepped shaft, and the third front cover stepped shaft decrease in sequence. The second front cover stepped shaft has a front cover oil seal groove. The front cover internally has a first front cover hollow cavity, a second front cover hollow cavity, and a third front cover hollow cavity connected in sequence from left to right. A spiral oil guiding groove is provided in the third hollow cavity. A cylindrical front cover wrench hole is opened on the left end face of the front cover.

6. A thin hydraulic cylinder with an annular groove machined at the oil inlet, characterized in that, The second rear cover stepped shaft has a rear cover oil seal groove. A clearance groove is provided on the left end face of the rear cover. A lifting ring hole and a cylindrical rear cover wrench hole are opened on the right end face of the rear cover.

7. A thin hydraulic cylinder with an annular groove machined at the oil inlet according to claim 6, characterized in that, The interior of the piston has a through cylindrical piston hole, the diameter of the piston hole decreasing from left to right, and at least a part of the piston hole has internal threads; the side surface of the piston has a piston oil seal groove, and the left and right sides of the piston oil seal groove respectively have a first wear-resistant ring groove and a second wear-resistant ring groove, the width of the first wear-resistant ring groove being greater than the width of the second wear-resistant ring groove; chamfers are provided at both ends of the piston.

8. A thin hydraulic cylinder with an annular groove machined at the oil inlet, characterized in that, The front cover oil seal groove and the rear cover oil seal groove are both fitted with an O-ring and a back-up ring, the piston oil seal groove is fitted with a piston seal, and wear-resistant rings are provided in both the first wear-resistant ring groove and the second wear-resistant ring groove.

9. A thin hydraulic cylinder with an annular groove machined at the oil inlet, characterized in that, The piston rod has a first piston shaft, a second piston shaft, and a third piston shaft connected in sequence from left to right. The first piston shaft is assembled with a piston rod shaft cap; the second piston shaft is allowed to cooperate with the second hollow cavity and the third hollow cavity of the front cover, and the third piston shaft has an external thread that mates with the internal thread of the piston hole.

10. A thin hydraulic cylinder with an annular groove machined at the oil inlet, characterized in that, The second piston shaft is provided with a force application surface and a piston shaft oil seal groove, allowing an adjustable wrench to act on the force application surface to tighten the fit between the third piston shaft and the piston hole, and the piston shaft oil seal groove is fitted with an O-ring; the external thread of the third piston shaft is allowed to cooperate with a check screw.

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