A high-temperature resistant and long-life U-shaped sealing ring and its preparation method

Abstract

The present invention relates to a high-temperature resistant and long-life U-shaped sealing ring and a preparation method thereof, belonging to the technical field of sealing rings. It includes an annular ring body. A main lip and a secondary lip are provided at the upper end of the ring body. The main lip is located on the inner ring and abuts against the piston rod. An installation groove is formed at the contact position between the main lip and the piston rod. A patch layer is provided in the installation groove of the main lip. The patch layer is made of a high-temperature resistant material. The angle between the upper end of the patch layer and the vertical direction is the main lip oil surface angle, and the designed angle of the main lip oil surface angle is 50±5°. This application has the advantages of high temperature resistance, good sealing performance, and long service life.

Description

Technical Field

[0001] The present invention relates to a U-shaped sealing ring with high temperature resistance and long service life and a preparation method thereof, belonging to the technical field of sealing rings. Background Art

[0002] As a kind of sealing for construction machinery cylinders, the traditional structure of the U-shaped sealing ring is made of integral polyurethane material, and mainly made of injection molding material TPU. Polyurethane elastomer belongs to polymer materials and is widely used in the sealing industry due to its elasticity and some excellent physical properties.

[0003] During the operation of the cylinder, friction occurs between the piston rod and the U-shaped sealing ring, and the temperature will gradually rise to 120 °C. The U-shaped sealing ring made of polyurethane material will undergo heat-resistant aging, the color will become darker and blacker, and then the physical properties of the material will decrease significantly, losing elasticity, resulting in oil leakage; at the same time, when the temperature rises, the hardness of the material will be significantly reduced, and the root is extremely prone to extrusion and gnawing damage, seriously affecting the service life of the U-shaped sealing ring. Summary of the Invention

[0004] In view of the deficiencies of the existing technology, the present invention provides a U-shaped sealing ring with high temperature resistance and long service life and a preparation method thereof.

[0005] In a first aspect, the technical solution of the present invention to solve the above technical problems is as follows: A U-shaped sealing ring with high temperature resistance and long service life, including an annular ring body. The upper end of the ring body is provided with a main lip and a secondary lip. The main lip is located on the inner ring and abuts against the piston rod. An installation groove is opened at the contact between the main lip and the piston rod. A patch layer is provided in the installation groove of the main lip. The patch layer is made of a high-temperature resistant material. The angle between the upper end of the patch layer and the vertical direction is the main lip oil surface angle, and the designed degree of the main lip oil surface angle is 50 ± 5°.

[0006] The beneficial effects of adopting the above solution are: A patch layer is provided at the contact between the main lip and the piston rod. The high-temperature resistance performance of the patch layer is superior to that of the ring body, main lip and secondary lip made of polyurethane material. When the cylinder operates, the patch layer abuts against the piston rod, can withstand high temperature and repeated friction, and is not prone to problems of physical property decline, and thus is not prone to oil leakage problems. With the long-term operation of the cylinder, when the temperature rises, the U-shaped sealing ring is not prone to problems of hardness reduction, and is also not prone to problems of root extrusion and gnawing damage, thereby ensuring the service life of the U-shaped sealing ring. In addition, setting the angle of the main lip oil surface angle to 50 ± 5° can change the pressure gradient distribution at the main lip, improve the pressure gradient at the main lip, and still maintain good sealing performance when the sealing ring bears high frequency and high pressure, thus ensuring the service life of the U-shaped sealing ring from another aspect.

[0007] On the basis of the above technical solution, the present invention can also be improved as follows:

[0008] Furthermore, the thickness of the patch layer ranges from 0.8 mm to 1.0 mm.

[0009] The beneficial effect of adopting the above further scheme is: the thickness of the patch layer is set between 0.8-1.0mm. When the patch layer contacts the piston rod, the deformation amount and the contact area are moderate, so that the main lip pressure can be distributed and concentrated at the main lip, which can improve the pressure gradient to a certain extent and further ensure the sealing effect.

[0010] Furthermore, the patch layer includes a first layer and a second layer, the first layer and the second layer are arranged at an angle, the angle between the first layer and the second layer is a lip angle, the design degree of the lip angle is θ+55°, and θ is the degree of the main lip oil surface angle.

[0011] Furthermore, the auxiliary lip is provided with a slope 1 at one end away from the main lip, the angle between the slope 1 and the vertical direction is the auxiliary lip oil surface angle, the design degree of the auxiliary lip oil surface angle is 45°±5°, and the auxiliary lip is provided with a slope 2 that conflicts with the slope 1, the angle between the slope 2 and the vertical direction is the auxiliary lip air surface angle, the design degree of the auxiliary lip air surface angle is 0.6α-15°, and α is the degree of the auxiliary lip oil surface angle.

[0012] Furthermore, the angle between the second block layer and the vertical direction is the main lip air surface angle, the design degree of the main lip air surface angle is 0.6θ-10°, a U-groove is left between the main lip and the auxiliary lip, the angle at the U-groove is the U-groove angle, and the design degree of the U-groove angle is 30°±10°.

[0013] In a second aspect, the technical solution of the present invention to solve the above technical problem is as follows: a method for preparing a high temperature resistant and long-life U-shaped sealing ring comprises the following steps:

[0014] S1: firstly, the patch layer is activated by using a modified treatment liquid, then the activated patch layer is cleaned by using a cleaning liquid, and then the cleaned patch layer is dried to obtain an activated patch layer;

[0015] S2: Weigh 75-80 parts by weight of isocyanate, 10-20 parts of polycaprolactone and 5-10 parts of dihydroxyethyl ether of hydroquinone, mix the above raw materials, and after sufficient reaction, obtain modified polyurethane, extrude and granulate the modified polyurethane, and then cool and dry it to obtain modified polyurethane particles;

[0016] S3: Place the activated patch layer in the mold. Meanwhile, heat and melt the modified polyurethane particles, and inject the melted modified polyurethane into the mold. After the polyurethane cools down, a U-shaped sealing ring can be obtained.

[0017] Further, the modification treatment liquid in S1 includes 34.5 parts by weight of sodium, 1160 parts of naphthalene, and 445 - 1335 parts of tetrahydrofuran.

[0018] The steps for activating the patch layer are as follows:

[0019] Step 1: Prepare the modification treatment liquid: First, weigh sodium and naphthalene, mix them together to obtain a sodium naphthalene mixture, control the concentration of the sodium naphthalene mixture at 1.5 - 2.0 mol / L, and then add tetrahydrofuran to the sodium naphthalene mixture to obtain the modification treatment liquid.

[0020] Step 2: Inject the modification treatment liquid into the surface treatment tank, then place the patch layer in the surface treatment tank, cover the tank lid, and the treatment time is 50 - 60 s.

[0021] Step 3: Take out the treated patch layer from the modification treatment liquid, and quickly place the treated patch layer in the cleaning liquid treatment tank for cleaning. The cleaning liquid is tetrahydrofuran, and then dry the cleaned patch layer to obtain the activated patch layer.

[0022] Further, when drying the cleaned patch layer in Step 3, first put the cleaned patch layer on a stainless steel pipe, then place the stainless steel pipe in a drying oven, control the temperature at 20 - 30 °C, and the drying time is ≥2 h.

[0023] Further, when injecting the modified polyurethane in S3, the injection pressure is 50 - 60 MPa, the injection temperature is 195 - 200 °C, the back pressure is 2.8 - 3 MPa, and the cooling time is 25 - 30 s.

[0024] Further, after withdrawing the U-shaped sealing ring from the mold in S3, post-treat the U-shaped sealing ring. Specifically, perform heat preservation treatment on the U-shaped sealing ring. The post-treatment is divided into two stages. The temperature in the first-stage post-treatment is 120 - 125 °C, the post-treatment time is 20 - 24 h, and the cooling time is 4 h. The temperature in the second-stage post-treatment is 115 - 120 °C, the post-treatment time is 16 - 20 h, and the cooling time is furnace cooling. After the furnace cooling ends, the U-shaped sealing ring is obtained.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. In this application, a patch layer is provided at the main lip, and the patch layer is made of a high-temperature resistant material. The designed degree of the main lip oil surface angle is 50 ± 5°. When the oil cylinder operates, the patch layer has a strong ability to withstand high temperatures and is not prone to problems of physical property degradation. Therefore, when the oil cylinder operates for a long time, it is not prone to oil leakage problems. At the same time, by controlling the main lip oil surface angle, the pressure gradient acting at the main lip is increased, further improving the sealing performance of the U-shaped seal ring.

[0027] 2. In this application, by activating the patch layer, the molecular activity of the patch layer can be stimulated, enhancing the adhesion between the patch layer and the main lip, making the patch layer not easily fall off from the main lip, and further extending the service life of the U-shaped ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic cross-sectional structure diagram of a high-temperature resistant and long-life U-shaped seal ring in an embodiment of this application;

[0029] Figure 2 It is a schematic structure diagram highlighting the main lip oil surface angle in an embodiment of this application;

[0030] In the figure, 1. Ring body; 11. Root part; 12. Waist part; 2. Main lip; 21. Installation groove; 3. Patch layer; 31. First block layer; 32. Second block layer; 4. Auxiliary lip; 41. First inclined surface; 42. Second inclined surface; 5. U groove; 6. Main lip oil surface angle; 7. Main lip gas surface angle; 8. Lip corner angle; 9. Auxiliary lip oil surface angle; 90. Auxiliary lip gas surface angle; 99. U groove angle. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0033] There are no particular restrictions on the sources of all the raw materials of the present invention, and they can be purchased on the market or prepared according to the conventional methods well-known to those skilled in the art; the patch layer before activation treatment used in the present invention is specially ordered according to its own size and material requirements. The test methods involved in the present invention are all conventional methods unless otherwise specified.

[0034] As Figure 1 and Figure 2 shown, a high-temperature resistant and long-life U-shaped sealing ring includes an annular ring body 1. One end of the ring body 1 is provided with a main lip 2 and a secondary lip 4. The other end of the ring body 1 is a heel 11, and the middle part of the ring body 1 is a waist 12. The ring body 1, the main lip 2 and the secondary lip 4 are integrally formed, and the ring body 1, the main lip 2 and the secondary lip 4 are all made of polyurethane material. The main lip 2 is located on the inner ring and abuts against the piston rod. An installation groove 21 is opened at the contact part between the main lip 2 and the piston rod. The main lip 2 is provided with a patch layer 3 adapted to the installation groove 21 at the installation groove 21. The patch layer 3 is made of PTFE material. The patch layer 3 can withstand a maximum temperature of 260 °C. When the oil cylinder operates, the patch layer 3 abuts against the piston rod. Under high temperature, the patch layer 3 is not prone to problems such as aging and blackening of color, and at the same time, the end part of the ring body 1 is not prone to problems such as gnawing. In addition, by setting the patch layer 3, the friction coefficient between the U-shaped sealing ring and the piston rod is reduced, the friction resistance during the reciprocating process is reduced, the starting pressure of the system is reduced, and at the same time, the problem of heat generation at the lip is alleviated, thereby prolonging the service life of the U-shaped sealing ring, and at the same time reducing the problems of hydraulic oil accumulation and leakage at the piston rod. The oil cylinder can still operate normally under harsh working conditions such as high speed and high temperature. By setting the high-temperature resistant patch layer 3, most of the engineering problems such as oil cylinder shutdown and frequent maintenance can be effectively solved, the service life of the oil cylinder can be effectively prolonged, and a large amount of costs can be saved in terms of manpower and material resources.

[0035] As Figure 1 and Figure 2 shown, the thickness range of the patch layer 3 is 0.8 mm - 1.0 mm. After the patch layer 3 abuts against the piston rod within this thickness range, the deformation amount and the contact area are appropriate, thereby enabling the pressure to be concentrated at the main lip 2, and further increasing the pressure gradient at the main lip 2, thus ensuring the sealing effect.

[0036] As Figure 1 and Figure 2As shown, the patch layer 3 includes a first layer 31 and a second layer 32, the angle between the cross section of the first layer 31 away from the main lip 2 and the vertical direction is the main lip oil surface angle 6, the design angle of the main lip oil surface angle 6 is 50±5°, the first layer 31 and the second layer 32 are inclined, the angle between the first layer 31 and the second layer 32 is the lip angle 8, the design angle of the lip angle 8 is θ+55°, the angle between the second layer 32 and the vertical direction is the main lip air surface angle 7, the design angle of the main lip air surface angle 7 is 0.6θ-10°, θ is the degree of the main lip oil surface angle 6, when the main lip oil surface angle 6, When the angles of the main lip air surface angle 7 and the lip angle 8 meet the above-mentioned angle settings, when the main lip 2 conflicts with the piston rod, the contact width between the main lip 2 and the piston rod can be controlled within 0.5 mm, thereby improving the followability of the main lip 2, and thus the pressure gradient acting on the oil seal lip is large. When the cylinder is operated at a high frequency, it is not easy for hydraulic oil to leak from the main lip 2, which can improve the sealing effect. At the same time, the contact area with the piston rod can be reduced, so that the contact area with the piston rod is maintained within an appropriate range, reducing the friction between the piston rod and the piston rod. When the cylinder is operated for a long time, the service life of the U-shaped sealing ring can be guaranteed.

[0037] like Figure 1 and Figure 2 As shown, an inclined plane 41 is provided at one end of the auxiliary lip 4 away from the main lip 2, and the angle between the inclined plane 41 and the vertical direction is the auxiliary lip oil surface angle 9, and the design angle of the auxiliary lip oil surface angle 9 is 45°±5°. The auxiliary lip 4 is provided with an inclined plane 42 that conflicts with the inclined plane 41, and the angle between the inclined plane 42 and the vertical direction is the auxiliary lip air surface angle 90, and the design angle of the auxiliary lip air surface angle 90 is 0.6α-15°, α is the degree of the auxiliary lip oil surface angle 9, when the angle between the auxiliary lip oil surface angle 9 and the auxiliary lip air surface angle 90 meets the above angle setting, when the oil cylinder is running, the auxiliary lip 4 can absorb part of the pressure transmitted from the main lip 2, which can reduce the main lip 2 and the auxiliary lip. The pressure difference between the two lip parts 4 can protect the main lip 2 to a certain extent, thereby extending the service life of the U-shaped sealing ring and ensuring the sealing performance of the U-shaped sealing ring. In addition, when the oil cylinder is shut down from high-frequency operation, the auxiliary lip 4 can be subjected to a more uniform force on the seal, which can reduce the damage to the auxiliary lip 4 and further extend the service life of the U-shaped sealing ring. At the same time, by designing the angles of the oil surface angle of the auxiliary lip 4 and the air surface angle of the auxiliary lip 4, when the oil cylinder is shut down, the heel 11 of the ring body 1 can be compressed, and the stress at the waist 12 can be reduced, so that the pressure is normally distributed during static sealing, the sealing performance during static sealing is improved, and the problem of hydraulic oil leakage when the oil cylinder is shut down is reduced.

[0038] like Figure 1 and Figure 2As shown, there is a U-groove 5 left between the main lip 2 and the secondary lip 4. The angle at the U-groove 5 is the U-groove 5 angle, and the designed degree of the U-groove 5 angle is 30° ± 10°. When the U-groove 5 angle is 30° ± 10°, during the operation of the oil cylinder, the medium pressure acts on the waist 12 of the lip, and the pressure can be effectively transmitted to the main lip 2. As the medium pressure increases, the pressure at the main lip 2 also increases. The radial part of this pressure can be converted into a sealing force, thereby improving the sealing effect at the main lip 2 and making the sealing of this U-shaped seal ring more reliable.

[0039] Preparation example of modified treatment liquid

[0040] Preparation example 1 of modified treatment liquid

[0041] Weigh 34.5 kg of sodium, 1160 kg of naphthalene, and 445 kg of tetrahydrofuran. First, dissolve the sodium in naphthalene to prepare a sodium naphthalide treatment liquid, and then add 445 kg of tetrahydrofuran to the sodium naphthalide treatment liquid to prepare a modified treatment liquid with a concentration of 1.0 mol / L.

[0042] Preparation example 2 of modified treatment liquid

[0043] The difference between this preparation example and Preparation example 1 of the modified treatment liquid is that the amount of tetrahydrofuran added is 778.75 kg. Then, through calculation, it can be known that the concentration of the modified treatment liquid at this time is 0.8 mol / L.

[0044] Preparation example 3 of modified treatment liquid

[0045] The difference between this preparation example and Preparation example 1 of the modified treatment liquid is that the amount of tetrahydrofuran added is 1335 kg. Then, through calculation, it can be known that the concentration of the modified treatment liquid at this time is 0.6 mol / L.

[0046] Preparation example 4 of modified treatment liquid

[0047] The difference between this preparation example and Preparation example 1 of the modified treatment liquid is that the amount of tetrahydrofuran added is 1780 kg. Then, through calculation, it can be known that the concentration of the modified treatment liquid at this time is 0.5 mol / L.

[0048] Preparation example 5 of modified treatment liquid

[0049] The difference between this preparation example and Preparation example 1 of the modified treatment liquid is that the amount of tetrahydrofuran added is 323.96 kg. Then, through calculation, it can be known that the concentration of the modified treatment liquid at this time is 1.1 mol / L.

[0050] Example 1

[0051] A preparation method for a high-temperature resistant and long-life U-shaped seal ring includes the following steps:

[0052] Step 1: First, arrange the patch layer neatly and hang each piece on the hanging rod. Then, place the hanging rods of the hung patch layer neatly on the bracket. The material of the patch layer is PTFE. Measure 35 L of the modified treatment liquid obtained in Preparation Example 1 of the modified treatment liquid, and inject the modified treatment liquid into the surface treatment tank. Then, place the bracket with the patch layer into the surface treatment tank, cover the upper cover of the surface treatment tank, and the treatment time is 50 s. Immediately after the treatment is completed, take out the patch layer from the surface treatment tank, and quickly place the treated patch layer in the cleaning liquid treatment tank for cleaning. The cleaning liquid injected into the cleaning liquid treatment tank is tetrahydrofuran. Rinse the patch layer in the tetrahydrofuran cleaning liquid for 30 s, then put the cleaned patch layer on a stainless steel pipe with an outer diameter slightly smaller than the inner diameter of the patch layer, and then place the stainless steel pipe in the drying oven. Control the temperature of the drying oven at 20 °C, and the drying time is 2 h. After the drying is completed, the activated patch layer can be obtained;

[0053] Step 2: Weigh 75 kg of isocyanate, 10 kg of polycaprolactone, and 5 kg of hydroquinone dihydroxyethyl ether. After mixing the above raw materials in the reaction kettle, control the temperature in the reaction kettle between 100 °C and 110 °C, keep warm and stir for 4 h to obtain the modified polyurethane. Extrude and granulate the modified polyurethane, and then cool and dry it to obtain the modified polyurethane particles;

[0054] Step 3: Place the activated patch layer obtained in Step 1 in the mold. At the same time, heat and melt the modified polyurethane particles, and then inject the melted modified polyurethane into the mold. When injecting the polyurethane, the injection pressure is 50 Mpa, the injection temperature is 195 °C, the back pressure is 2.8 Mpa, and the cooling time is 25 s. After demolding, the injection-molded U-shaped sealing ring can be obtained;

[0055] Step 4: Perform post-treatment on the injection-molded U-shaped sealing ring obtained in Step 3. Specifically, place the U-shaped sealing ring in the treatment furnace for heat preservation treatment. The post-treatment is divided into two stages. The temperature of the first-stage post-treatment is 120 °C, the post-treatment time is 20 h, and the cooling time is 4 h; the temperature of the second-stage post-treatment is 115 °C, the post-treatment time is 16 h, and the cooling time is furnace cooling. After the furnace cooling is completed, the U-shaped sealing ring can be obtained.

[0056] In this Example 1, the thickness of the patch layer is 0.8 mm, the main lip oil surface angle is 45 °, the lip angle is 100 °, the main lip gas surface angle is 17 °, the secondary lip oil surface angle is 40 °, the secondary lip gas surface angle is 9 °, and the U-groove angle is 20 °.

[0057] Example 2

[0058] The difference between this Example and Example 1 is that in Step 1, the patch layer is treated with the modified treatment liquid obtained in Preparation Example 2 of the modified treatment liquid, and the other raw material ratios and process parameters are the same as those in Example 1.

[0059] Example 3

[0060] The difference between this example and Example 1 is that in the first step, the patch layer is treated with the modified treatment liquid obtained in Preparation Example 3 of the modified treatment liquid, and the other raw material ratios and process parameters are the same as those in Example 1.

[0061] Example 4

[0062] The difference between this example and Example 1 is that in the first step, the treatment time of the patch layer with the modified treatment liquid is 60 s, and the drying temperature of the cleaned patch layer is 30 °C, and the other raw material ratios and process parameters are the same as those in Example 1.

[0063] Example 5

[0064] The difference between this example and Example 1 is that in the second step, 80 kg of isocyanate, 20 kg of polycaprolactone and 10 kg of hydroquinone dihydroxyethyl ether are weighed, and the other raw material ratios and process parameters are the same as those in Example 1.

[0065] Example 6

[0066] The difference between this example and Example 1 is that when injecting the polyurethane in the third step, the injection pressure is 60 Mpa, the injection temperature is 200 °C, the back pressure is 3 Mpa, and the cooling time is 30 s, and the other raw material ratios and process parameters are the same as those in Example 1.

[0067] Example 7

[0068] The difference between this example and Example 1 is that in the fourth step, the temperature of the first-stage post-treatment is 125 °C, the post-treatment time is 24 h, and the cooling time is 4 h; the temperature of the second-stage post-treatment is 120 °C, and the post-treatment time is 20 h, and the other raw material ratios and process parameters are the same as those in Example 1.

[0069] Example 8

[0070] The difference between this example and Example 1 is that the thickness of the patch layer is 0.9 mm, the main lip oil surface angle is 50 °, the lip opening angle is 105 °, the main lip gas surface angle is 20 °, the secondary lip oil surface angle is 45 °, the secondary lip gas surface angle is 12 °, and the U-groove angle is 30 °.

[0071] Example 9

[0072] The difference between this example and Example 1 is that the thickness of the patch layer is 1.0 mm, the main lip oil surface angle is 55 °, the lip opening angle is 110 °, the main lip gas surface angle is 23 °, the secondary lip oil surface angle is 50 °, the secondary lip gas surface angle is 15 °, and the U-groove angle is 40 °.

[0073] Comparative Example

[0074] Comparative Example 1

[0075] The difference between this comparative example and Example 1 is that in the first step, the modified treatment liquid obtained in Preparation Example 4 is used to treat the patch layer, and the other raw material ratios and process parameters are the same as those in Example 1.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is that in the first step, the modified treatment liquid obtained in Preparation Example 5 is used to treat the patch layer, and the other raw material ratios and process parameters are the same as those in Example 1.

[0078] Comparative Example 3

[0079] The difference between this comparative example and Example 1 is that in the first step, tetrahydrofuran is not used to rinse the patch layer after the treatment, and the other raw material ratios and process parameters are the same as those in Example 1.

[0080] Comparative Example 4

[0081] The difference between this comparative example and Example 1 is that in the first step, the treatment time of the patch layer with the modified treatment liquid is 45 s, and the other raw material ratios and process parameters are the same as those in Example 1.

[0082] Comparative Example 5

[0083] The difference between this comparative example and Example 1 is that in the first step, the treatment time of the patch layer with the modified treatment liquid is 65 s, and the other raw material ratios and process parameters are the same as those in Example 1.

[0084] Comparative Example 6

[0085] The difference between this comparative example and Example 1 is that in the third step, ordinary commercially available polyurethane particles are heated and melted and then injection molded, and the other raw material ratios and process parameters are the same as those in Example 1.

[0086] Comparative Example 7

[0087] The difference between this comparative example and Example 1 is that in the fourth step, the injection-molded U-shaped sealing ring is not subjected to the first-stage post-treatment, but directly to the second-stage post-treatment, and the other raw material ratios and process parameters are the same as those in Example 1.

[0088] Comparative Example 8

[0089] The difference between this comparative example and Example 1 is that in the fourth step, the injection-molded U-shaped sealing ring is not subjected to the second-stage post-treatment. After the first-stage post-treatment of the injection-molded U-shaped sealing ring, the U-shaped sealing ring is obtained, and the other raw material ratios and process parameters are the same as those in Example 1.

[0090] Comparative Example 9

[0091] The difference between this comparative example and Example 1 is that in the fourth step, the injection-molded U-shaped sealing ring is not subjected to the first-stage and second-stage post-treatment, and the other raw material ratios and process parameters are the same as those in Example 1.

[0092] Comparative Example 10

[0093] The difference between this comparative example and Example 1 is that in the first step, the patch layer is not activated, and the ordinary patch layer and the modified polyurethane are directly injection-molded together, and the other raw material ratios and process parameters are the same as those in Example 1.

[0094] Comparative Example 11

[0095] The difference between this comparative example and Example 1 is that the U-shaped sealing ring is integrally injection-molded from modified polyurethane and has no patch layer, and the other raw material ratios and process parameters are the same as those in Example 1.

[0096] Comparative Example 12

[0097] The difference between this comparative example and Example 1 is that the thickness of the patch layer is 0.7 mm, and the other raw material ratios and process parameters are the same as those in Example 1.

[0098] Comparative Example 13

[0099] The difference between this comparative example and Example 1 is that the thickness of the patch layer is 1.1 mm, and the other raw material ratios and process parameters are the same as those in Example 1.

[0100] Comparative Example 14

[0101] The difference between this comparative example and Example 1 is that the degree of the oil-facing angle of the main lip is 43°, the degree of the lip corner is 98°, and the degree of the gas-facing angle of the main lip is 15.8°, and the other raw material ratios and process parameters are the same as those in Example 1.

[0102] Comparative Example 15

[0103] The difference between this comparative example and Example 1 is that the degree of the lip corner is 108°, and the degree of the gas-facing angle of the main lip is 23°, and the other raw material ratios and process parameters are the same as those in Example 1.

[0104] Comparative Example 16

[0105] The difference between this comparative example and Example 1 is that the degree of the oil-facing angle of the secondary lip is 37°, and the degree of the gas-facing angle of the secondary lip is 7.2°, and the other raw material ratios and process parameters are the same as those in Example 1.

[0106] Comparative Example 17

[0107] The difference between this comparative example and Example 1 lies in that the degree of the secondary lip gas surface angle is 14.8°, and the other raw material ratios and process parameters are the same as those in Example 1.

[0108] Comparative Example 18

[0109] The difference between this comparative example and Example 1 lies in that the degree of the U-groove angle is 17°, and the other raw material ratios and process parameters are the same as those in Example 1.

[0110] Comparative Example 19

[0111] The difference between this comparative example and Example 1 lies in that the degree of the U-groove angle is 43°, and the other raw material ratios and process parameters are the same as those in Example 1.

[0112] Test and Detection

[0113] Take the U-shaped sealing rings obtained in Examples 1-9 and Comparative Examples 1-11 as test samples. Take 5 U-shaped sealing rings in each group for detection. Install the U-shaped sealing rings into the oil cylinder and detect the service life of the U-shaped sealing rings at high frequency (the frequency gradually increases to 40 Hz). When the patch layer falls off from the main lip or there is a problem of hydraulic oil leakage, it is the end of the service life of the U-shaped sealing ring. In order to accelerate the test progress, the detection is carried out in a microwave environment. In the test data, the microwave acceleration time is converted into normal working time for data comparison. After detecting the samples, record the test data and calculate the average value of the experimental data. The specific test results are shown in Table 1-1:

[0114] Table 1-1 Test Data of Examples 1-9 and Comparative Examples 1-11

[0115]

[0116]

[0117] Perform sealing detection on the samples obtained from Example 1, Example 8 and 9 and Comparative Examples 12-19. Extract 10 samples in each group. After installing the samples in the oil cylinder, let the oil cylinder work at a frequency of 40 Hz for 1000 h, and then observe the leakage situation of the hydraulic oil. Divide the leakage situation into 5 grades: no leakage, slight leakage, leakage, moderate leakage and severe leakage. Record no leakage as 0, slight leakage as 1, leakage as 2, moderate leakage as 3, and severe leakage as 4. Accumulate the scores of each sample in each group. By comparing the score situations of each group, the quality of the sealing performance can be intuitively judged. After recording and calculating the data, Table 1-2 can be obtained:

[0118] Table 1-2 Test Data of Example 1, 8, 9 and Comparative Examples 12-19

[0119]

[0120]

[0121] Analysis of test results:

[0122] Combined with Examples 1-9 and Comparative Examples 1-19, and combined with Tables 1-1 and 1-2, the test results can be analyzed as follows:

[0123] 1. It can be seen from Examples 1-3 that when the concentration range of the modified treatment liquid is 0.6-1.0 mol / L, and the patch layer is activated with the modified treatment liquid within this concentration range, the service life of the U-shaped sealing ring can reach more than 3000 hours. Moreover, when the concentration of the modified treatment liquid is changed within a reasonable range, the service life of the U-shaped sealing ring does not change significantly;

[0124] 2. It can be seen from Examples 4-7 that when the test parameters in the present invention are changed within the parameter range specified in the present invention, it has basically no effect on the service life of the U-shaped sealing ring, and the service life of the U-shaped sealing ring can still be maintained above 3000 hours;

[0125] 3. It can be seen from Example 1 and Comparative Examples 1 and 2 that when the concentration of the modified treatment liquid is 0.5 mol / L or 1.1 mol / L, after the patch layer is treated with the modified treatment liquid at this concentration, the service life of the U-shaped sealing ring is lower than that of the U-shaped sealing ring obtained in Example 1. Therefore, it shows that too high or too low concentration of the modified treatment liquid will have an adverse effect on the service life of the U-shaped sealing ring;

[0126] 4. It can be seen from Example 1 and Comparative Example 3 that if the patch layer is not cleaned with tetrahydrofuran after the U-shaped sealing ring is treated with the modified treatment liquid, it has a great impact on the service life of the U-shaped sealing ring, which also reflects the importance of rinsing the treated patch layer with tetrahydrofuran from the side;

[0127] 5. It can be seen from Example 1 and Comparative Examples 4 and 5 that when the patch layer is treated with the modified treatment liquid, too short or too long treatment time will have an adverse effect on the service life of the U-shaped sealing ring. Therefore, it shows that the treatment time of the patch layer with the modified treatment liquid is crucial for the service life of the U-shaped sealing ring;

[0128] 6. It can be seen from Example 1 and Comparative Example 6 that compared with the modified polyurethane in the present invention, the commercially available ordinary polyurethane material has a poor bonding strength with the patch layer. The modified polyurethane in the present invention has better heat resistance and bonding strength with the patch layer. Therefore, using the modified polyurethane can ensure the service life of the U-shaped sealing ring;

[0129] 7. As can be seen from Example 1 and Comparative Examples 7-9, the necessity of post-treatment for the U-shaped sealing ring can be observed. When only one-stage post-treatment and two-stage post-treatment are carried out on the U-shaped sealing ring, the service life of the U-shaped sealing ring is only more than two thousand hours. However, when neither one-stage post-treatment nor two-stage post-treatment is carried out, the service life of the U-shaped sealing ring is only more than one thousand seven hundred hours. Therefore, it shows the important influence of one-stage post-treatment and two-stage post-treatment on the life of the U-shaped sealing ring, and at the same time shows the synergistic influence of one-stage post-treatment and two-stage post-treatment on the service life of the U-shaped sealing ring;

[0130] 8. As can be seen from Example 1 and Comparative Example 10, when the patch layer is not activated, the service life of the U-shaped sealing ring is only more than one thousand two hundred hours, and the bonding strength between the patch layer and the main lip is poor. Therefore, it reflects the importance of activating the patch layer, and further shows that activating the patch layer can effectively improve the bonding strength between the patch layer and the main lip;

[0131] 9. As can be seen from Example 1 and Comparative Example 11, when the high-temperature resistant patch layer is not provided, the service life of the U-shaped sealing ring is short. Therefore, it shows the importance of setting the patch layer for the service life of the U-shaped sealing ring, which can effectively improve the high-temperature resistance of the U-shaped sealing ring, reduce the friction coefficient of the oil seal lip, reduce the friction resistance during the reciprocating movement, lower the system startup pressure, and at the same time reduce the heat generation at the lip, prolonging the service life of the U-shaped sealing ring;

[0132] 10. As can be seen from Example 1, 8 and 9, adjusting the thickness of the patch layer, the oil surface angle of the main lip, the lip angle, the air surface angle of the main lip, the oil surface angle of the secondary lip, the air surface angle of the secondary lip and the U-groove angle within an appropriate range has no effect on the sealing performance of the U-shaped sealing ring, and after the oil cylinder operates for a long time, the U-shaped sealing ring can still maintain good sealing performance;

[0133] 11. As can be seen from Example 1 and Comparative Examples 12 and 13, when the thickness of the patch layer is 0.7 mm and 1.1 mm, the sealing performance of the U-shaped sealing ring significantly drops. This shows the necessity of limiting the thickness of the patch layer, and at the same time shows that the limited thickness of the patch layer in the present invention is the optimal thickness;

[0134] 12. As can be seen from Example 1 and Comparative Examples 14 and 15, when the degree of the main lip oil surface angle deviates from the range of 50±5°, the sealing performance of the U-shaped sealing ring decreases significantly. Therefore, it shows the necessity of limiting the degree of the main lip oil surface angle within a certain range in the present invention, and at the same time, it also shows that the range of the degree of the main lip oil surface angle limited in the present invention is a better range. In addition, it can also be seen that when the size relationship between the main lip oil surface angle, the lip angle, and the main lip gas surface angle does not meet the range formula, the sealing performance of the U-shaped sealing ring is also poor. Therefore, it shows that limiting the values between the main lip oil surface angle, the lip angle, and the main lip gas surface angle in the present invention can ensure the sealing performance of the U-shaped sealing ring;

[0135] 13. As can be seen from Example 1 and Comparative Examples 16 and 17, when the degree of the secondary lip oil surface angle deviates from the range of 45±5°, the sealing performance of the U-shaped sealing ring also decreases significantly. Therefore, it shows that limiting the degree of the secondary lip oil surface angle within a certain range in the present invention can ensure the sealing performance of the U-shaped sealing ring. In addition, when the relationship between the secondary lip oil surface angle and the secondary lip gas surface angle does not meet the formula defined in the present invention, the sealing performance of the U-shaped sealing ring is also poor. Therefore, it shows that limiting the values between the secondary lip oil surface angle and the secondary lip gas surface angle in the present invention can ensure the sealing performance of the U-shaped sealing ring;

[0136] 14. As can be seen from Example 1 and Comparative Examples 18 and 19, when the U-groove angle does not meet the range of 20-40°, it will also have a negative impact on the sealing performance of the U-shaped sealing ring, resulting in a decrease in the sealing performance of the U-shaped sealing ring. Therefore, it shows that limiting the U-groove angle in the present invention can ensure the sealing performance of the U-shaped sealing ring.

[0137] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0138] The above-described embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A preparation method of a high-temperature resistant and long-life U-shaped sealing ring, the high-temperature resistant and long-life U-shaped sealing ring comprising an annular ring body (1), characterized in that: The upper end of the ring body (1) is provided with a main lip (2) and a secondary lip (4). The main lip (2) is located on the inner ring and abuts against the piston rod. An installation groove (21) is formed at the contact position between the main lip (2) and the piston rod. A patch layer (3) is arranged in the installation groove (21) of the main lip (2). The patch layer (3) is made of a high-temperature resistant material. The included angle between the upper end of the patch layer (3) and the vertical direction is the main lip oil surface angle (6), and the designed angle of the main lip oil surface angle (6) is 50±5°; The preparation method of the high-temperature resistant and long-life U-shaped sealing ring is characterized by comprising the following steps: S1: First, activate the patch layer with a modification treatment liquid, then clean the activated patch layer with a cleaning liquid, and then dry the patch layer after the cleaning is completed to obtain an activated patch layer; S2: Weigh 75-80 parts by weight of isocyanate, 10-20 parts of polycaprolactone and 5-10 parts of hydroquinone dihydroxyethyl ether. Mix the above raw materials and fully react to obtain a modified polyurethane. Extrude and granulate the modified polyurethane, and then cool and dry it to obtain modified polyurethane particles; S3: Place the activated patch layer in a mold, and at the same time heat and melt the modified polyurethane particles. Inject the melted modified polyurethane into the mold. After the polyurethane cools, a U-shaped sealing ring can be obtained; Among them, the modification treatment liquid in S1 includes 34.5 parts by weight of sodium, 1160 parts of naphthalene and 445-1335 parts of tetrahydrofuran; The activation treatment steps for the patch layer are as follows: Step 1: Prepare the modification treatment liquid: First, weigh sodium and naphthalene, mix sodium and naphthalene together to obtain a sodium naphthalene mixed solution, control the concentration of the sodium naphthalene mixed solution at 1.5-2.0 mol / L, and then add tetrahydrofuran to the sodium naphthalene mixed solution to obtain the modification treatment liquid; Step 2: Inject the modification treatment liquid into the surface treatment tank, then place the patch layer in the surface treatment tank, cover the tank cover, and the treatment time is 50-60 s; Step 3: Take out the treated patch layer from the modification treatment liquid, and quickly place the treated patch layer in the cleaning liquid treatment tank for cleaning. The cleaning liquid is tetrahydrofuran, and then dry the cleaned patch layer to obtain the activated patch layer.

2. The preparation method of the high-temperature resistant and long-life U-shaped sealing ring according to claim 1, characterized in that: The thickness range of the patch layer (3) is 0.8 mm - 1.0 mm.

3. The preparation method of the high-temperature resistant and long-life U-shaped sealing ring according to claim 1, characterized in that: The patch layer (3) includes a first block layer (31) and a second block layer (32). The first block layer (31) and the second block layer (32) are inclined. The included angle between the first block layer (31) and the second block layer (32) is the lip angle (8), and the designed degree of the lip angle (8) is θ + 55°, where θ is the degree of the main lip oil surface angle (6).

4. The preparation method of the high-temperature resistant and long-life U-shaped sealing ring according to claim 1, characterized in that: The auxiliary lip (4) is provided with a sloped surface 1 (41) at one end away from the main lip (2), the angle between the sloped surface 1 (41) and the vertical direction is the auxiliary lip oil surface angle (9), the design degree of the auxiliary lip oil surface angle (9) is 45°±5°, the auxiliary lip (4) is provided with a sloped surface 2 (42) which conflicts with the sloped surface 1 (41), the angle between the sloped surface 2 (42) and the vertical direction is the auxiliary lip air surface angle (90), the design degree of the auxiliary lip air surface angle (90) is 0.6α-15°, α is the degree of the auxiliary lip oil surface angle (9).

5. The preparation method of the high-temperature resistant and long-life U-shaped sealing ring according to claim 3, characterized in that: The angle between the second layer (32) and the vertical direction is the main lip air surface angle (7), and the design degree of the main lip air surface angle (7) is 0.6θ-10°. A U groove (5) is left between the main lip (2) and the auxiliary lip (4), and the angle at the U groove (5) is the U groove (5) angle, and the design degree of the U groove (5) angle is 30°±10°.

6. The preparation method of the high-temperature resistant and long-life U-shaped sealing ring according to claim 1, characterized in that: When drying the cleaned patch layer in step 3, the cleaned patch layer is first put on the stainless steel tube, and then the stainless steel tube is placed in a drying oven, the temperature is controlled at 20-30° C., and the drying time is ≥2h.

7. The preparation method of the high-temperature resistant and long-life U-shaped sealing ring according to claim 1, characterized in that: When the modified polyurethane is injection molded in S3, the injection pressure is 50-60 MPa, the injection temperature is 195-200° C., the back pressure is 2.8-3 MPa, and the cooling time is 25-30 s.

8. The preparation method of the high-temperature resistant and long-life U-shaped sealing ring according to claim 1, characterized in that: After the U-shaped sealing ring is withdrawn from the mold in S3, the U-shaped sealing ring is post-processed, specifically, the U-shaped sealing ring is subjected to heat preservation treatment. The post-processing is divided into two stages. The temperature of the first stage post-processing is 120-125°C, the post-processing time is 20-24h, and the cooling time is 4h; the temperature of the second stage post-processing is 115-120°C, the post-processing time is 16-20h, and the cooling time is furnace cooling. After the furnace cooling is completed, the U-shaped sealing ring is obtained.

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