Guide sleeve for hydraulic oil cylinder and preparation method of guide sleeve

Abstract

The guide sleeve comprises a sleeve body, the sleeve body is of a hollow structure with the two ends communicated with each other, the sleeve body comprises a shaft sleeve and an outer barrel which are coaxially arranged, the shaft sleeve is sleeved with the outer barrel, and a plurality of station holes penetrating through the inner wall and the outer wall of the shaft sleeve are formed in the circumferential face of the shaft sleeve; a station hole is formed in the outer cylinder, a solid lubricant is embedded in the station hole, so that friction resistance of the piston is achieved by making contact with the solid lubricant when the piston reciprocates, a limiting component used for limiting the shaft sleeve to be disengaged from a port is arranged at one end of the outer cylinder, and a locking unit used for fixing the shaft sleeve in an inner cavity of the outer cylinder is arranged at the other end of the outer cylinder. The friction force is reduced, and the operation stability of the piston is improved.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic cylinder accessories, and more specifically, to a guide sleeve for a hydraulic cylinder and a preparation method thereof. Background Art

[0002] Hydraulic cylinders are widely used in various mechanical equipment. One of its core components is the guide sleeve. The main function of the guide sleeve is to guide the reciprocating motion of the piston rod and bear the lateral force of the piston rod. During use, the guide sleeve needs to have high wear resistance and stability to ensure the normal operation of the hydraulic cylinder and extend the service life of the equipment. However, due to the high-frequency contact between the piston rod and the guide sleeve and the high-load operating conditions, the guide sleeve often faces serious wear problems. In order to improve the wear resistance of the guide sleeve and the activity efficiency of the piston rod, CN114483702B discloses a hydraulic cylinder guide sleeve with wear-resistant function. The guide sleeve is provided with a curved roller on the inner wall of the guide sleeve that is in rolling contact with the piston rod. When the piston rod moves, the curved roller rotates, so that the piston rod of the hydraulic cylinder moves smoothly and reduces the wear caused by friction.

[0003] The above-mentioned prior art has a complex structure and is difficult to form. In addition, during the contact between the piston rod and the curved roller, the thickness of the curved roller increases the distance between the piston rod and the inner wall of the guide sleeve, which leads to unstable hydraulic oil pressure.

[0004] In order to improve the wear resistance of the guide sleeve and the stability of the piston rod, there is another way, which is to set a solid lubricant in the guide sleeve. The specific structure is such as an oil-free bearing. However, this structure is to open a hole in its brass body and then fill the hole with a solid lubricant such as graphite. The traditional oil-free bearing structure is designed for rotary motion systems. It mainly deals with the centrifugal force and axial force generated in the rotary motion. The centrifugal force acts on the periphery of the bearing component, causing the lubricant to remain stable and reduce friction during the rotation process. The axial force is applied along the axial direction. However, in the application of hydraulic cylinder guide sleeves, the piston rod mainly reciprocates back and forth, and this movement will generate radial force (acting in a direction perpendicular to the axis of the piston rod). In some cases, slight axial force may also occur. The traditional oil-free bearing design is not suitable for the environment where this force acts, because the stability of the solid lubricant is difficult to maintain in reciprocating motion, which may lead to reduced lubrication effect and increased wear. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a guide sleeve for a hydraulic cylinder which has a reasonable and simple structure, strong practicality, reduces friction, and improves the running stability of the piston, and a preparation method thereof.

[0006] To achieve the above object, the present invention provides the following technical solutions: A guide sleeve for a hydraulic cylinder comprises a sleeve body, the sleeve body is a hollow structure with two ends connected to each other, the sleeve body comprises a coaxially arranged shaft sleeve and an outer cylinder, the outer cylinder is sleeved outside the shaft sleeve, A plurality of workstation holes penetrating the inner and outer walls of the sleeve are provided on the circumferential surface of the sleeve, and solid lubricants are embedded in the workstation holes so as to reduce the friction resistance of the piston by contacting the solid lubricants when the piston reciprocates. A limiting component for limiting the sleeve from being separated from the port is disposed on one end of the outer cylinder, and a locking unit for fixing the sleeve in its inner cavity is disposed on the other end of the outer cylinder.

[0007] The present invention is further configured as follows: the locking unit comprises a sealing cover with an outer peripheral wall having an external thread and a screw rod penetrating through the sealing cover and connecting the outer cylinder, The inner wall of the outer cylinder is provided with an internal thread for threaded connection of the sealing cover. The bottom end surface of the sealing cover is pressed on the top surface of the shaft sleeve, and the bottom surface of the shaft sleeve is pressed on the limiting component.

[0008] The present invention is further configured as follows: a guide groove is provided on the inner peripheral wall of the outer cylinder, and a convex strip matched with the guide groove is provided on the outer peripheral wall of the sleeve to lock the axial rotation of the sleeve.

[0009] The present invention is further configured as follows: a positioning hole for a screw to penetrate through the body of the sealing cover is provided on the top surface of the sealing cover.

[0010] The present invention is further configured as follows: an annular groove is provided on the bottom surface of the shaft sleeve, and an O-ring is provided in the annular groove.

[0011] The present invention is further configured such that: a solid lubricant is provided on the inner wall of the sealing cover.

[0012] A method for preparing a guide sleeve for a hydraulic cylinder comprises the following steps: S1. Shaft sleeve processing: S1-1, punching the sleeve along the thickness direction to obtain workstation holes by a punching device, and the workstation holes are evenly distributed on the circumferential wall of the sleeve; S1-2, roughening the inner wall of the work station hole, i.e. using sandblasting to increase friction; S1-3, implanting the solid lubricant into the station hole by a press-fitting method, and placing the sleeve in a heat treatment furnace in an inert gas environment for heating treatment; S2, outer cylinder processing: milling the inner wall of one end of the outer cylinder to obtain an internal thread, and milling the inner wall of the outer cylinder to obtain a guide groove; S3, assembly: S3-1, first align the convex strip of the sleeve with the guide groove so that the sleeve is inserted into the outer tube until it contacts the limiting component; S3-2, place the sealing cover into the port of the outer cylinder, and rotate the sealing cover until it cannot rotate axially; S3-3. Insert the screw into the positioning hole and tighten the positioning hole thread until the axial direction cannot rotate, thereby completing the assembly.

[0013] The present invention is further configured as follows: the specific steps of step S1-3 are as follows: S1-3-1, mixing solid lubricant powder and resin powder evenly to prepare a dry powder mixture, then filling the dry powder mixture into a hollow part of a mold, and performing high-pressure pressing on the mixture by a pressing process to form a solid lubricant compact; S1-3-2, using the press-fitting method to embed the solid lubricant compact into the station hole; S1-3-3. Place the guide sleeve embedded with the solid lubricant compact in a heat treatment furnace in a vacuum or inert gas environment for heating treatment.

[0014] The present invention is further configured as follows: the heating treatment step in step S1-3-3 is as follows: S01. Stage 1: Preliminary Heating Slowly raise the temperature to 120°C-150°C at a rate of 2°C-5°C / min and maintain for 30-60 minutes to drive out residual moisture and volatile components in the compact to prevent expansion cracks or uneven solidification during subsequent heating; S02, second stage: main curing heating Continue to heat up to 180°C - 200°C, control the heating rate at 2°C-3°C / min, and keep at this temperature for 1-2 hours to fully solidify the resin and ensure a firm bond between the compact and the hole wall; S03, the third stage: sintering and expansion Raise the temperature to 220°C - 240°C and maintain for 30 - 60 minutes to allow the solid lubricant to expand and sinter in the pores to form a porous structure; S04, Stage 4: Slow Cooling Slowly cool to room temperature at a rate of 2°C -5°C / min to avoid thermal stress accumulation and material cracking caused by sudden temperature drop, and ensure the stability of the porous lubricant structure.

[0015] Compared with the shortcomings of the prior art, the beneficial effects of the present invention are: After the sleeve is installed in the outer cylinder, the contact between the threaded sealing cap and the top surface of the sleeve is ensured to be tightly fixed to prevent any loosening or displacement. The guide groove on the inner wall of the cylinder cooperates with the convex strip on the outer wall of the sleeve, so that the sleeve is not only passively fixed in the outer cylinder, but also effectively prevents rotation or slight axial movement. This design ensures that the sleeve can always maintain the correct centering state under the action of radial force and slight axial force, thereby avoiding wear and system failure caused by rotation or displacement.

[0016] Through the step-by-step temperature control heat treatment method, it is ensured that the solid lubricant is fully solidified in the work station hole and forms a porous structure. This porous structure can provide continuous lubrication during reciprocating motion and significantly improve the wear resistance of the guide sleeve. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an exploded schematic diagram of the guide sleeve of the present invention; Figure 2 It is a cross-sectional view of a guide sleeve of the present invention.

[0018] Bushing 1, outer cylinder 2, solid lubricant 3, limit component 21, locking unit 4, sealing cover 41, screw 42, O-ring 5, guide groove 20, convex strip 11, positioning hole 40, connecting hole 30, DETAILED DESCRIPTION

[0019] Reference Figure 1 to Figure 2 The embodiments of the present invention are further described.

[0020] The specific structure of this embodiment includes a sleeve body, which is a hollow structure with two ends interconnected. The sleeve body includes a coaxially arranged sleeve 1 and an outer cylinder 2, and the outer cylinder 2 is sleeved outside the sleeve 1.

[0021] A plurality of station holes penetrating the inner and outer walls of the sleeve 1 are provided on the circumferential surface thereof, and solid lubricants 3 are embedded in the station holes so as to reduce the friction resistance of the piston by contacting the solid lubricants 3 when the piston reciprocates. The station holes are tapered, and after the lubricant is embedded and solidified, the mechanical locking effect can improve the installation stability of the lubricant. The distance between two adjacent station holes is 1.5 times the aperture of the station holes.

[0022] A limiting component 21 is provided on one end of the outer cylinder 2 for limiting the sleeve 1 from being separated from the port, and a locking unit 4 is provided on the other end of the outer cylinder 2 for fixing the sleeve 1 in its inner cavity, the locking unit 4 includes a sealing cover 41 with an external thread on the outer peripheral wall and a screw 42 that passes through the sealing cover 41 and connects the outer cylinder 2, and an internal thread for threaded connection of the sealing cover 41 is provided on the inner wall of the outer cylinder 2, the bottom end surface of the sealing cover 41 is pressed on the top surface of the sleeve 1, the bottom surface of the sleeve 1 is pressed on the limiting component 21, and a connecting hole for inserting the screw 42 is provided on the top end surface of the sleeve 1.

[0023] A guide groove 20 is provided on the inner circumferential wall of the outer cylinder 2, and a convex strip 11 matching the guide groove 20 is provided on the outer circumferential wall of the sleeve 1 to prevent the sleeve 1 from rotating or shifting under the action of radial force or slight axial force, thereby ensuring the stable operation of the system. An annular groove is provided on the bottom surface of the sleeve 1, and an O-ring 5 is provided in the annular groove to enhance the sealing performance of the contact end surface of the sleeve 1 and the outer cylinder 2.

[0024] A positioning hole 40 for the screw 42 to penetrate the body of the sealing cover 41 is provided on the top surface thereof, and a solid lubricant 3 is provided on the inner wall of the sealing cover 41. The sealing cover 41 comprises two parts, one is a main body for threaded connection with the outer cylinder 2, and the other is a pressing plate part for pressing on the port of the outer cylinder 2 and flush with the inner wall of the outer cylinder 2. The length of the shaft sleeve 1 is just sandwiched between the sealing cover 41 and the limiting component 21, and they are pressed against each other.

[0025] The preparation method of the guide sleeve for the hydraulic cylinder comprises the following steps: Step 1: Shaft sleeve processing: Use a punching device to punch holes along the thickness direction of the shaft sleeve to obtain workstation holes, which are evenly distributed on the circumferential wall of the shaft sleeve; Roughen the inner wall of the workstation hole, i.e. use sandblasting to increase friction; The solid lubricant powder and the resin powder are mixed evenly to prepare a dry powder mixture, and then the dry powder mixture is filled into the hollow part of the mold, and the mixture is pressed under high pressure by a pressing process to form a solid lubricant compact.

[0026] The solid lubricant powder is polytetrafluoroethylene, and the resin powder is, for example, phenolic resin.

[0027] The solid lubricant compact is embedded in the station hole by a press-fitting method, and then the guide sleeve embedded with the solid lubricant compact is placed in a heat treatment furnace in a vacuum or inert gas environment for heating treatment. The heating treatment steps are as follows: The first stage, preliminary heating: slowly increase the temperature to 120°C-150°C at a rate of 2°C-5°C / min and maintain for 30-60 minutes to drive out residual moisture and volatile components in the compact to prevent expansion cracks or uneven solidification during subsequent heating.

[0028] The second stage, main curing heating: continue to heat up to 180°C - 200°C, the heating rate is controlled at 2°C-3°C / minute, and maintain this temperature for 1-2 hours to fully cure the resin and ensure a firm bond between the compact and the hole wall.

[0029] The third stage, sintering and expansion: the temperature is raised to 220°C - 240°C and maintained for 30 - 60 minutes to allow the solid lubricant to expand and sinter in the pores to form a porous structure The fourth stage, slow cooling: Slowly cool to room temperature at a rate of 2°C -5°C / minute to avoid thermal stress accumulation and material cracking caused by sudden temperature drop, and ensure the stability of the porous lubricant structure.

[0030] Step 2: Processing the outer cylinder: Mill the inner wall of one end of the outer cylinder to obtain the internal thread, and mill the inner wall of the outer cylinder to obtain the guide groove; Step 3: Assemble: First, align the convex strip of the sleeve with the guide groove so that the sleeve is inserted into the outer cylinder until it contacts the limit component; Place the sealing cover into the port of the outer cylinder and rotate the sealing cover until it cannot rotate axially; The assembly is completed by inserting the screw into the positioning hole and locking the positioning hole thread until the axial direction cannot rotate.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A guide sleeve for a hydraulic cylinder, characterized in that: The sleeve body comprises a sleeve body, which is a hollow structure with two ends connected to each other. The sleeve body comprises a coaxially arranged shaft sleeve (1) and an outer cylinder (2), wherein the outer cylinder (2) is sleeved outside the shaft sleeve (1). A plurality of workstation holes penetrating the inner and outer walls of the shaft sleeve (1) are provided on the circumferential surface thereof, and solid lubricants (3) are embedded in the workstation holes so that when the piston reciprocates, the piston contacts the solid lubricant (3) to reduce the friction resistance of the piston. A limiting component (21) for limiting the sleeve (1) from being disengaged from the port is provided on one end of the outer cylinder (2), and a locking unit (4) for fixing the sleeve (1) in its inner cavity is provided on the other end of the outer cylinder (2).

2. According to claim 1, a guide sleeve for a hydraulic cylinder is characterized in that: The locking unit (4) comprises a sealing cover (41) having an outer peripheral wall with external threads and a screw (42) penetrating the sealing cover (41) and connecting the outer cylinder (2). The inner wall of the outer cylinder (2) is provided with an internal thread for threaded connection of the sealing cover (41). The bottom end surface of the sealing cover (41) is pressed onto the top surface of the shaft sleeve (1), and the bottom surface of the shaft sleeve (1) is pressed onto the limiting component (21).

3. According to claim 2, a guide sleeve for a hydraulic cylinder is characterized in that: A guide groove (20) is provided on the inner peripheral wall of the outer cylinder (2), and a convex strip (11) adapted to the guide groove (20) is provided on the outer peripheral wall of the shaft sleeve (1) so as to lock the axial rotation of the shaft sleeve (1).

4. The guide sleeve for a hydraulic cylinder according to claim 3, characterized in that: A positioning hole (40) for a screw rod (42) to pass through the body of the sealing cover (41) is provided on the top surface of the sealing cover (41).

5. The guide sleeve for a hydraulic cylinder according to claim 4, characterized in that: An annular groove is provided on the bottom surface of the shaft sleeve (1), and an O-ring (5) is provided in the annular groove.

6. The guide sleeve for a hydraulic cylinder according to claim 5, characterized in that: A solid lubricant (3) is provided on the inner wall of the sealing cover (41).

7. A method for preparing a guide sleeve for a hydraulic cylinder according to claim 6, characterized in that: The steps include: S1. Shaft sleeve processing: S1-1, punching the sleeve along the thickness direction to obtain workstation holes by a punching device, and the workstation holes are evenly distributed on the circumferential wall of the sleeve; S1-2, roughening the inner wall of the work station hole, i.e. using sandblasting to increase friction; S1-3, implanting the solid lubricant into the station hole by a press-fitting method, and placing the sleeve in a heat treatment furnace in an inert gas environment for heating treatment; S2, outer cylinder processing: milling the inner wall of one end of the outer cylinder to obtain an internal thread, and milling the inner wall of the outer cylinder to obtain a guide groove; S3, assembly: S3-1, first align the convex strip of the sleeve with the guide groove so that the sleeve is inserted into the outer tube until it contacts the limiting component; S3-2, place the sealing cover into the port of the outer cylinder, and rotate the sealing cover until it cannot rotate axially; S3-3. Insert the screw into the positioning hole and tighten the positioning hole thread until the axial direction cannot rotate, thereby completing the assembly.

8. The method for preparing a guide sleeve for a hydraulic cylinder according to claim 7, characterized in that: The specific steps of step S1-3 are as follows: S1-3-1, mixing solid lubricant powder and resin powder evenly to prepare a dry powder mixture, then filling the dry powder mixture into a hollow part of a mold, and performing high-pressure pressing on the mixture by a pressing process to form a solid lubricant compact; S1-3-2, using the press-fitting method to embed the solid lubricant compact into the station hole; S1-3-3. Place the guide sleeve embedded with the solid lubricant compact in a heat treatment furnace in a vacuum or inert gas environment for heating treatment.

9. The method for preparing a guide sleeve for a hydraulic cylinder according to claim 8, characterized in that: The heating process in step S1-3-3 is as follows: S01. Stage 1: Preliminary Heating Slowly raise the temperature to 120°C-150°C at a rate of 2°C-5°C / min and maintain for 30-60 minutes to drive out residual moisture and volatile components in the compact to prevent expansion cracks or uneven solidification during subsequent heating; S02, second stage: main curing heating Continue to heat up to 180°C - 200°C, control the heating rate at 2°C-3°C / minute, and keep at this temperature for 1-2 hours to fully solidify the resin and ensure a firm bond between the compact and the hole wall; S03, the third stage: sintering and expansion Raise the temperature to 220°C - 240°C and maintain for 30 - 60 minutes to allow the solid lubricant to expand and sinter in the pores to form a porous structure; S04, Stage 4: Slow Cooling Slowly cool to room temperature at a rate of 2°C -5°C / min to avoid thermal stress accumulation and material cracking caused by sudden temperature drop, and ensure the stability of the porous lubricant structure.

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