Preparation method of molded self-lubricating sliding bearing liner and injection mold

Abstract

The invention discloses a preparation method of a molded self-lubricating sliding bearing liner and an injection mold. The method comprises the steps of material mixing, material storage, injection and curing. According to the method, injection molding is performed through an injection molding machine, so that the problems of incompactness, weak bearing capacity, short service life and the like of the molded liner are solved. Due to the fact that the problems that in the injection molding process, a runner is prone to being blocked by glue, resin is prone to being cured and the like exist, the invention further provides a design method of the sliding bearing forming mold so as to solve related problems in the injection molding process.

Description

TECHNICAL FIELD

[0001] The present application relates to a self-lubricating plain bearing, more particularly to a method for preparing a self-lubricating plain bearing liner and an injection mold. BACKGROUND

[0002] A plain bearing is composed of an inner ring, a liner and an outer ring. Due to the special sleeve structure of the friction pair, the inner ring of the plain bearing can swing within a certain angle range. A self-lubricating plain bearing is a plain bearing with a layer of liner added in the gap between the inner and outer rings, so that the friction between the surface of the liner and the inner ring replaces the friction between the steel surfaces. Therefore, the self-lubricating plain bearing usually has the characteristics of small size, light weight, easy disassembly and assembly, maintenance-free, long running time, etc. Based on these advantages, most of the key transmission parts, wings, landing gears, propellers and control systems of aircrafts use self-lubricating plain bearings. With the development of technology, plain bearings are increasingly widely used in the fields of aviation, aerospace, military and other fields, and therefore the requirements for various performance indicators of plain bearings are also increasingly high. Therefore, it is of great significance to carry out research on the friction and wear performance of plain bearings and to find a new type of self-lubricating material to improve the tribological performance between the steel / steel friction pair of the plain bearing, enhance the use performance of the plain bearing and prolong the service life of the plain bearing.

[0003] A large amount of research work has been done on the types, properties and surface treatment methods of the inner and outer rings of self-lubricating materials at home and abroad. Among them, the application of fabric liners has developed the most rapidly, and certain research results have been achieved in the aspects of friction and wear, life calculation and test methods of self-lubricating plain bearings. However, in actual production, the liner is usually manually attached to the inner surface of the outer ring of the plain bearing, which not only has low production efficiency, but also the quality of the attachment is affected by many factors such as the type of adhesive, the weaving pattern of the liner, the proficiency of the worker, etc., all of which are directly related to the quality and service life of the plain bearing. As a special kind of self-lubricating bearing material, the molded solid self-lubricating plain bearing liner can effectively solve the problem of friction and wear of self-lubricating plain bearings under harsh working conditions. First of all, the molded bearing adopts a heating and curing forming method, the process is fixed, the technology is simple, and the product quality is stable; secondly, the liner of the molded bearing is a flowable material before curing, which can be injected into various shaped cavities, and the requirement for the structure of the bearing is relatively small, and the liner is more compact after curing and forming, has strong load capacity and is more wear-resistant; in addition, the molded bearing liner is more resistant to water, corrosion and weather due to its chemical inertness, and has a longer service life.

[0004] The existing molded plain bearing liner is mostly prepared and formed by means of dropping or injection with a syringe, which not only has low efficiency, but also lacks a certain mechanical forming pressure, so that the liner is not compact after curing and forming, has weak load capacity and a short service life. SUMMARY

[0005] The following is a summary of subject matter of the detailed description herein. This summary is not intended to limit the scope of protection of the present application.

[0006] To solve the problem of molding of the molded self-lubricating sliding bearing pad, the present application provides a preparation method of a molded self-lubricating sliding bearing pad, which is injection molded by an injection molding machine to solve the problems of non-densification, weak load capacity, short service life, etc. after molding.

[0007] The first aspect of the present application provides a preparation method of a molded self-lubricating sliding bearing pad, which is injection molded by a thermosetting resin injection molding machine.

[0008] In an exemplary embodiment, the method comprises the following steps: 1) mixing: the raw materials are added to the feeding machine in proportion for mixing, and after the raw materials are uniformly dispersed in the feeding machine, the material cylinder above the screw of the injection molding machine is added; 2) storing: the screw is rotated and retreated to the desired position, and at the same time, the mixed material in the material cylinder is added to the screw area for storage; 3) injection: before injection, the mold is closed and the mold is pressed; during injection, the mixed material is pushed into the mold by rotating the screw; after injection, the mold is pressure maintained to complete the injection; 4) curing: the pressure when the mold is closed is maintained, the mold is heated, the bearing pad is cured and formed, the mold is opened, and the product is ejected, thereby obtaining the molded self-lubricating sliding bearing pad.

[0009] In an exemplary embodiment, step 1) comprises: adding raw materials to the feeding machine in proportion for mixing, the stirring speed of the feeding machine is 10-1000 r / min (for example, 10 r / min, 100 r / min, 110 r / min, 1000 r / min); after the raw materials are uniformly dispersed, the material cylinder above the screw of the injection molding machine is added for feeding, and the feeding speed is 0.1-10 mm / s (for example, 0.1 mm / s, 1 mm / s, 2 mm / s, 10 mm / s). 3 3 3 3 3

[0010] In an exemplary embodiment, the stirring speed of the feeding machine in step 1) is 80-300 r / min.

[0011] In an exemplary embodiment, the stirring time of the feeding machine in step 1) is 5-60 min (for example, 5 min, 30 min, 35 min, 60 min).​​​​​

[0012] In an exemplary embodiment, step 1) further comprises: during the stirring, the feeding machine is further connected with an air source to press the mixture to help the dispersion.

[0013] In an exemplary embodiment, in step 1), the pressure of the air source is 0.2-2 MPa (for example, 0.2 MPa, 0.6 MPa, 0.7 MPa, 2.0 MPa); preferably, 0.4-1 MPa.

[0014] In an exemplary embodiment, in step 1), the feeding speed of the feeding machine is 0.5-2 mm / s. 3 / s.

[0015] In an exemplary embodiment, in step 1), the feeding machine is provided with a precise feeding function, and the feeding amount of the feeding machine each time is 5-10 g, preferably 5-8 g.

[0016] In an exemplary embodiment, step 2) comprises: setting the rotating speed of the screw to 10-200 r / min (for example, 10 r / min, 60 r / min, 70 r / min, 200 r / min), and after the screw rotates, the mixture in the barrel is added to the screw area for storage.

[0017] In an exemplary embodiment, in step 2), the rotating speed of the screw is 50-80 r / min.

[0018] In an exemplary embodiment, in step 2), the storage position of the screw is 10-300 mm (for example, 10 mm, 60 mm, 70 mm, 300 mm).

[0019] In an exemplary embodiment, in step 2), a reverse storage back pressure of 0.01-1 MPa (for example, 0.01 MPa, 0.1 MPa, 0.2 MPa, 1.0 MPa) is applied to the screw during the storage.

[0020] In an exemplary embodiment, step 3) comprises: before injection, first close the mold, the closing pressure is 5-150 MPa (for example, 10 MPa, 130 MPa, 140 MPa, 150 MPa), and vacuumize the mold; during injection, set the screw rotation speed to 10-300 r / min (for example, 10 r / min, 100 r / min, 110 r / min, 300 r / min), the injection pressure is 5-150 MPa (for example, 5 MPa, 40 MPa, 50 MPa, 150 MPa), the injection stroke is 10-50 mm (for example, 10 mm, 25 mm, 30 mm, 50 mm), and the mixture is pushed into and injected into the mold; after injection, the mold is pressure-kept, the pressure-keeping pressure is 1-30 MPa (for example, 1 MPa, 10 MPa, 11 MPa, 30 MPa), the pressure-keeping time is 1-20 s (for example, 1 s, 5 s, 6 s, 20 s), and the vacuumization of the mold interval is closed after the pressure-keeping is finished, and the injection is completed.

[0021] In an exemplary embodiment, in step 3), the closing pressure is 30-100 MPa.

[0022] In an exemplary embodiment, in step 3), the vacuum degree during closing is 0.01 MPa.

[0023] In an exemplary embodiment, in step 3), the screw rotation speed during injection is 50-120 r / min.

[0024] In an exemplary embodiment, in step 3), the pressure during injection is 30-100 MPa.

[0025] In an exemplary embodiment, in step 3), the injection stroke is 20-40 mm.

[0026] In an exemplary embodiment, in step 3), the screw advance speed during injection is 20-200 mm / s (for example, 20 mm / s, 70 mm / s, 80 mm / s, 200 mm / s).

[0027] In an exemplary embodiment, in step 3), the pressure-keeping pressure is 5-15 MPa.

[0028] In an exemplary embodiment, in step 3), the screw rotation speed during pressure-keeping is 10-300 r / min.

[0029] In an exemplary embodiment, step 4) comprises: maintaining the pressure when the mold is closed, heating the mold to 50-150℃ (for example, 50℃, 120℃, 125℃, 150℃), heating the mold for 2-60min (for example, 2min, 10min, 15min, 60min), until the bearing liner is cured and shaped, opening the mold, and ejecting the product, thereby obtaining the molded self-lubricating sliding bearing liner.

[0030] In an exemplary embodiment, in step 4), the mold heating temperature is 100-130℃.

[0031] In an exemplary embodiment, in step 4), the mold heating time is 10-20min.

[0032] In an exemplary embodiment, in step 4), the mold opening speed when the mold is opened is 1-200mm / s (for example, 1mm / s, 40mm / s, 50mm / s, 200mm / s).

[0033] In an exemplary embodiment, in step 4), the ejection speed when the product is ejected is 1-100mm / s (for example, 1mm / s, 20mm / s, 30mm / s, 100mm / s).

[0034] In an exemplary embodiment, in the method, the barrel, mold and screw zone are respectively connected with a cold water machine.

[0035] In an exemplary embodiment, the cooling water temperature in the cold water machine is 0-20℃, preferably 0-5℃.

[0036] The second aspect of the present application provides a molded self-lubricating sliding bearing liner prepared by the above method.

[0037] The three aspects of the present application provide an injection mold for preparing the above molded self-lubricating sliding bearing liner, which at least comprises: a bearing positioning structure for positioning the inner and outer rings of the bearing; a cooling system comprising a multi-circuit parallel cooling water flow channel for cooling the mold and the flow channel in the mold; a heating and temperature control system for heating the material injected into the bearing to solidify, and for real-time measurement and temperature control of the internal temperature of the mold.

[0038] In an exemplary embodiment, the bearing positioning structure can be located in the center of the mold.

[0039] In an exemplary embodiment, the cooling water flow channel is connected with a water chiller for cooling the flow channel in the mold to maintain a low temperature and prevent the thermosetting resin from being cured in the flow channel of the mold due to heat.

[0040] In an exemplary embodiment, the heating temperature of the heating and temperature control system is not lower than 200 DEG C.

[0041] In an exemplary embodiment, the bearing positioning structure adopts a combination design of a radial module and an axial end face pressing mechanism; optionally, the axial end face pressing mechanism adopts a pressing plate with a pre-pressing spring. The structure of the axial end face pressing mechanism allows a constant pressure to be applied to the bearing end face when the mold is closed, effectively preventing the material from penetrating into the bearing end face or raceway during injection, and avoiding subsequent cleaning work.

[0042] In an exemplary embodiment, according to the material flow and heat distribution in the mold cavity, the cooling water flow channel is non-uniformly distributed and asymmetrically arranged, wherein the cooling water flow channel is densely arranged at the end of the material flow and the region with a thick cross section, and preferably, the number of the cooling water flow channels at the end of the material flow and the region with a thick cross section is doubled relative to the number of the cooling water flow channels in other regions. The gradient cooling design of the cooling water flow channel based on heat field analysis can realize rapid and uniform cooling of the mold, significantly eliminate internal thermal stress of the product, prevent warping deformation, and shorten the molding cycle. Compared with the simple and symmetric cooling holes in the prior art, the cooling efficiency of the cooling water flow channel of the present application is higher, and the quality of the obtained product is more stable.

[0043] In an exemplary embodiment, the heating and temperature control system adopts embedded partition heating and includes a multi-point temperature sensing integrated module. Specifically, a plurality of heating rods with independent temperature control are embedded and installed at the feeding port of the mold cavity, the core and other key regions, and a plurality of micro thermocouples are embedded on the surface and inside the cavity to form a closed-loop control system. The partition temperature control technology allows different temperature curves to be applied to different regions of the mold, thereby accurately controlling the curing rate and order of the material and effectively solving the defects such as too fast surface curing, internal bubble or incomplete curing caused by a single temperature.

[0044] Compared with the prior art, the present application has the following technical effects: The present application prepares a molded self-lubricating sliding bearing pad by an injection molding method, and a thermosetting material injection molding machine is used. Among them, 1) The feeding area of the injection molding machine has a mixing and precise feeding function, which can realize a continuous stirring state of the material to prevent the filler from being blocked in the flow channel, and at the same time, the injection program is linked, and after the injection action is completed, precise feeding is carried out, and the quality fluctuation of each feeding is within 1g.

[0045] 2) The screw zone has water cooling function, and the water cooling capacity needs to maintain the temperature at least at 5℃, so as to prevent the shear heat generated when the screw rotates from causing the resin to solidify.

[0046] 3) The mold integrates bearing positioning structure, cooling system, and heating and temperature control system, and the mold zone has water cooling, vacuumizing, and heating functions, the water cooling function ensures that the material will not solidify and block the flow channel, the vacuumizing function can prevent defects such as air bubbles and cracks in the product, and the heating function can realize the solidification of the resin in the mold.

[0047] 4) Since there are problems such as easy blocking of flow channel and easy solidification of resin during injection molding process, the application also provides a design method of the sliding bearing forming mold to solve the related problems during injection molding.

[0048] In summary, the injection molding method of the molded self-lubricating sliding bearing pad provided by the application not only creates a new bearing preparation method, but also improves the performance of the self-lubricating sliding bearing, and the process is simple and efficient, and continuous production can be realized, which has great production value.

[0049] Other features and advantages of the application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application. Other advantages of the application can be realized and obtained by means of the solutions described in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0050] The accompanying drawings are used to provide an understanding of the technical solutions of the application, and constitute a part of the specification, and together with the embodiments of the application are used to explain the technical solutions of the application, and do not constitute a limitation on the technical solutions of the application.

[0051] Figure 1 is a physical diagram of the molded self-lubricating plain bearing injection mold of the application; Figure 2 is a physical diagram of the injection molded bearing of the application; Figure 3 is a friction and wear curve diagram of the injection molded bearing of Example 1; Figure 4 is a physical diagram of the bearing prepared by drop method of Comparative Example 1; Figure 5 is a physical diagram of the bearing prepared by using the conventional injection mold of Comparative Example 2; Figure 6 is a friction and wear curve diagram of the injection molded bearing of Comparative Example 3; Figure 7 is a schematic diagram of the mold cooling water channel of the application; Figure 8 is a schematic diagram of the bearing positioning structure of the application.

[0052] Figure label: 1: Bearing; 2: Cooling water flow channel. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] Among them, such as Figure 1 , 7 As shown in Figure 8, the mold design used in this application for injection molding must include at least the following modules: (1) Cooling system, including multi-loop parallel cooling water channels 2; the cooling system is connected to a chiller and is used to cool the channels in the mold, maintain a low temperature, and prevent the thermosetting resin from solidifying in the mold channels due to heat. (2) Bearing positioning structure 1, used for positioning the inner and outer rings of the bearing; and (3) Heating and temperature control system (not shown), including a heating and temperature sensing module, which heats and solidifies the material injected into the bearing, and can measure the internal temperature of the mold in real time and control the temperature; the heating temperature of the heating and temperature control system is not lower than 200℃.

[0055] The preparation method of the molded self-lubricating sliding bearing gasket of this application is described in detail below.

[0056] Example 1: 1) Mixing: Thermosetting resin, carbon fiber, and polytetrafluoroethylene granules are added to the feeder in a mass ratio of 8:1:1 for mixing. The feeder's mixing speed is 100 r / min, and the mixing time is 30 min. During mixing, the feeder is connected to a 0.6 MPa pressure air source to aid dispersion. After the raw materials are evenly dispersed, they are fed into the barrel above the injection molding machine screw at a feeding speed of 1 mm / min. 3 / s.

[0057] 2) Material storage: Set the screw speed to 60 r / min, rotate and retract to the material storage position of 60 mm, and at the same time add the mixture in the barrel to the screw area, apply reverse material storage back pressure to the screw, the material storage back pressure is 0.1 MPa; the material storage area is connected to a chiller, and the temperature of the cooling water is set to 8℃.

[0058] 3) Injection: Before injection, the mold is closed with a clamping pressure of 150 MPa, and the mold is simultaneously evacuated to a vacuum degree of 0.01 MPa; during injection, the screw is rotated, the screw rotation speed is set to 100 r / min, and the injection pressure of 40 MPa is applied to the screw to push the material into the mold, at this time, the screw advancing speed is 80 mm / s, and the advancing distance is 25 mm; after injection, the mold is pressure-kept with a pressure of 10 MPa, the screw rotation speed is 100 r / min during pressure-keeping, and the pressure-keeping time is 5 s, after the pressure-keeping, the mold interval is closed to stop the vacuum, and the injection is completed. 4) Solidification: the mold is kept at a clamping pressure of 150 MPa, the mold is heated to a temperature of 120°C, and the heating time is 10 min, the bearing liner is solidified and formed, the mold is opened at an opening speed of 50 mm / s, the product is ejected at an ejection speed of 20 mm / s, and the molded self-lubricating sliding bearing liner is obtained.

[0059] Example 2: 1) Mixing: the thermosetting resin, carbon fiber and polytetrafluoroethylene particles are added into the feeding machine in a mass ratio of 7:1:2 for mixing, the stirring speed of the feeding machine is 110 r / min, the stirring time is 35 min, and the feeding machine is connected with a pressure source of 0.7 MPa during stirring; after the raw materials are uniformly dispersed, the material is added into the barrel above the injection molding machine screw for feeding, and the feeding speed is 2 mm / s. 3

[0060] 2) Storage: the rotation speed of the screw is set to 70 r / min, and the screw is rotated to retreat to the storage position of 70 mm; at the same time, the mixed material in the barrel is added into the screw area, and the reverse storage back pressure of 0.2 MPa is applied to the screw; the storage area is connected with a cold water machine, and the temperature of the cold water machine is set to 7°C, 3) Injection: before injection, the mold is closed with a clamping pressure of 140 MPa, and the mold is simultaneously evacuated to a vacuum degree of 0.01 MPa; during injection, the screw is rotated, the screw rotation speed is set to 110 r / min, and the injection pressure of 50 MPa is applied to the screw to push the material into the mold, at this time, the screw advancing speed is 70 mm / s, and the advancing distance is 30 mm; after injection, the mold is pressure-kept with a pressure of 11 MPa, the screw rotation speed is 90 r / min during pressure-keeping, and the pressure-keeping time is 6 s, after the pressure-keeping, the mold interval is closed to stop the vacuum, and the injection is completed.

[0061] 4) Solidification: the mold is kept at a clamping pressure of 140 MPa, the mold is heated to a temperature of 125°C, and the heating time is 15 min, the bearing liner is solidified and formed, the mold is opened at an opening speed of 40 mm / s, the product is ejected at an ejection speed of 30 mm / s.

[0062] Example 3:​ 1) Mixing: thermosetting resin, carbon fiber, polytetrafluoroethylene particles are added to the feeding machine in a mass ratio of 3:4:3, the stirring speed of the feeding machine is 1000 r / min, the stirring time is 60 min, and the feeding machine is connected with a pressure gas source of 2 MPa during stirring; after the raw materials are uniformly dispersed, the material cylinder above the injection molding machine screw is added for feeding, and the feeding speed is 10 mm 3 / s.

[0063] 2) Storage: the rotation speed of the screw is set to 200 r / min, and the rotation retreats to the storage position of 300 mm, and the mixed material in the material cylinder is added to the screw area, and the reverse storage back pressure is applied to the screw, and the storage back pressure is 1 Mpa; the storage area is connected with a cold water machine, and the temperature of the cold water machine is set to 20℃.

[0064] 3) Injection: before injection, the mold is closed, the mold closing pressure is 130 MPa, and the mold is vacuumized, and the vacuum degree is 0.01 MPa; before injection, the screw is rotated, the rotation speed of the screw is set to 300 r / min, and the injection pressure of 150 MPa is applied to the screw, and the material is pushed into the mold, at this time, the screw advances at a speed of 200 mm / s, and the advance distance is 50 mm; after injection, the mold is pressure maintained, the pressure maintaining pressure is 30 MPa, the rotation speed of the screw is 300 r / min during pressure maintaining, and the pressure maintaining time is 20 s; after pressure maintaining, the mold interval is closed, and the injection is completed.

[0065] 4) Curing: keep the mold closing pressure of 130 MPa, heat the mold, the heating temperature is 150℃, the heating time is 2 min, the bearing gasket is cured and formed, the mold is opened, the opening speed is 200 mm / s, the product is ejected, and the ejection speed is 100 mm / s.

[0066] Example 4: 1) Mixing: thermosetting resin, carbon fiber, polytetrafluoroethylene particles are added to the feeding machine in a mass ratio of 2:1:7, the stirring speed of the feeding machine is 10 r / min, the stirring time is 5 min, and the feeding machine is connected with a pressure gas source of 0.2 MPa during stirring; after the raw materials are uniformly dispersed, the material cylinder above the injection molding machine screw is added for feeding, and the feeding speed is 0.1 mm 3 / s.

[0067] 2) Storage: the rotation speed of the screw is set to 10 r / min, and the rotation retreats to the storage position of 10 mm, and the mixed material in the material cylinder is added to the screw area, and the reverse storage back pressure is applied to the screw, and the storage back pressure is 0.01 Mpa; the storage area is connected with a cold water machine, and the temperature of the cold water machine is set to 0℃.

[0068] 3) Injection: Before injection, the mold is closed with a clamping pressure of 10 MPa, and the mold is simultaneously evacuated to a vacuum degree of 0.01 MPa; during injection, the screw is rotated, the screw rotation speed is set to 10 r / min, the injection pressure is 5 MPa, the screw advance speed is 20 mm / s, and the advance distance is 10 mm; after injection is completed, the mold is pressure- maintained at a pressure of 1 MPa, the screw rotation speed is 10 r / min during pressure- maintaining, the pressure- maintaining time is 1 s, the mold interval is closed after pressure- maintaining is completed, and injection is completed.

[0069] 4) Curing: the mold is heated with a clamping pressure of 10 MPa, the heating temperature is 50°C, the heating time is 60 min, the bearing gasket is cured and formed, the mold is opened at an opening speed of 1 mm / s, the product is ejected at an ejection speed of 1 mm / s.

[0070] Comparative Example 1: Preparation condition: thermosetting resin, carbon fiber and polytetrafluoroethylene particles are mixed in a mass ratio of 3:4:3 (same as Example 3), the mixture is directly dropped into the mold cavity by a dropper, there is no injection pressure or screw action. The material flows by gravity, and there is no vacuum pumping. The curing conditions are the same as those in Example 3.

[0071] Comparative Example 2: Preparation condition: thermosetting resin, carbon fiber and polytetrafluoroethylene particles are mixed in a mass ratio of 3:4:3 (same as Example 3), a conventional injection mold is used, there is no vacuum pumping system, and the clamping pressure is 200 MPa (same as Example 3). The injection parameters and curing parameters are the same.

[0072] Comparative Example 3: 1) Mixing: thermosetting resin, carbon fiber and polytetrafluoroethylene particles are added to the feeding machine in a mass ratio of 2:1:7, the stirring speed of the feeding machine is 10 r / min, the stirring time is 5 min, and a pressure air source of 0.2 MPa is connected during stirring; after the raw materials are uniformly dispersed, the mixture in the barrel above the screw of the injection molding machine is added for feeding, and the feeding speed is 0.1 mm / s. 3

[0073] 2) Storage: the rotation speed of the screw is set to 10 r / min, and the screw is rotated to retreat to the storage position of 10 mm, and the mixture in the barrel is added to the screw zone at the same time, the reverse storage back pressure is applied to the screw, and the storage back pressure is 0.01 MPa; the storage zone is connected with a cold water machine, and the temperature of the cold water machine is set to 0°C.

[0074] ​3) Injection: Before injection, close the mold with a closing pressure of 1 MPa and simultaneously evacuate the mold to a vacuum level of 0.01 MPa. During injection, rotate the screw at a speed of 8 r / min, with an injection pressure of 1 MPa, a screw forward speed of 2 mm / s, and a forward stroke of 8 mm. After injection, maintain pressure on the mold at 0.5 MPa, with the screw speed at 8 r / min and the holding time at 0.5 s. After the holding time is complete, close the vacuum in the mold area to complete the injection.

[0075] 4) Curing: Maintain a mold closing pressure of 1MPa, heat the mold at 40℃ for 120min, and the bearing gasket will be cured and formed. Open the mold at a speed of 1mm / s and eject the product at a speed of 1mm / s.

[0076] test: 1. For example Figure 3 As shown, the sliding bearing prepared in Example 1 was subjected to 70,000 cycles under the following test conditions: room temperature, relative humidity of 50%-70%, swing angle of ±25°, and constant load of 230 MPa applied to the outer ring of the sliding bearing. The wear depth was less than 0.11 mm and the friction coefficient was less than 0.1, which meets the specifications of GJB 5502-2005 for low-speed oscillating self-lubricating radial sliding bearings.

[0077] 2. For example Figure 4 As shown, the bearing prepared by the drop-in method in Comparative Example 1 had incomplete material filling, resulting in voids and delamination. The product had poor dimensional accuracy and cracks appeared after curing, making it unsuitable for high-precision bearing applications.

[0078] 3. For example Figure 5 As shown, due to the low mold closing pressure and lack of vacuum, bubbles were generated in the bearing liner after Comparative Example 2 was cured, making it impossible to obtain a normal high-quality product.

[0079] 4. For example Figure 6 As shown, the sliding bearing prepared in Comparative Example 3, under test conditions of room temperature, relative humidity of 50%-70%, oscillation angle ±25°, and a constant load of 230 MPa applied to the outer ring of the sliding bearing, underwent 5000 cycles. The wear depth exceeded 0.11 mm, failing to meet the specifications of GJB 5502-2005 for low-speed oscillating self-lubricating radial sliding bearings. This is because low-pressure and low-speed injection lead to insufficient filling, and excessively short holding time causes dimensional instability or warping of the product. Low-temperature curing results in insufficient or no resin curing, reducing product hardness and wear resistance, and making it prone to brittleness.

[0080] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that changes, modifications, substitutions and variations can be made by those skilled in the art without departing from the scope of the present application.

Claims

1. A method for preparing a molded self-lubricating sliding bearing gasket, the method comprising injection molding using a thermosetting resin injection molding machine, and the following steps: 1) Mixing: Add the raw materials to the feeding machine according to the specified ratio for mixing. The mixing speed of the feeding machine is 10-1000 r / min. After the raw materials are evenly dispersed, feed them into the barrel above the screw of the injection molding machine at a feeding speed of 0.1-10 mm. 3 / s; 2) Material storage: The screw speed is set to 10-200 r / min. After the screw rotates and retracts to the material storage position, the mixture in the barrel is added to the screw area for material storage. 3) Injection: Before injection, close the mold with a closing pressure of 5-150MPa and evacuate the mold. During injection, set the screw speed to 10-300r / min, the injection pressure to 5-150MPa, and the injection stroke to 10-50mm to push the mixture into the mold. After injection, hold the mold under pressure of 1-30MPa for 1-20s. After holding the pressure, close the vacuum in the mold area to complete the injection. 4) Curing: Maintain the pressure when the mold is closed, heat the mold to 50-150℃, and heat the mold for 2-60 minutes until the bearing pad is cured and formed. Open the mold and eject the product to obtain the molded self-lubricating sliding bearing pad.

2. The method for preparing the molded self-lubricating sliding bearing bush according to claim 1, wherein, Step 1) further includes: during mixing, the feeder is also connected to an air source to apply pressure to the mixture to aid dispersion; and / or The feeding machine has a precision feeding function.

3. The method for preparing the molded self-lubricating sliding bearing bush according to claim 2, wherein, In step 1), the mixing speed of the feeder is 80-300 r / min; and / or The mixing time of the feeder is 5-60 minutes; and / or The pressure of the gas source is 0.2-2 MPa; and / or The feeding speed of the feeder is 0.5-2mm. 3 / s; and / or The feeding machine feeds 5-10g of material at a time.

4. The method for preparing the molded self-lubricating sliding bearing bushing according to claim 3, wherein, The pressure of the gas source is 0.4-1 MPa; and / or The feeding machine feeds 5-8g of material at a time.

5. The method for preparing a molded self-lubricating sliding bearing gasket according to any one of claims 1 to 4, wherein, In step 2), the screw speed is 50-80 r / min; and / or The screw's storage position is 10-300mm; and / or During material storage, a reverse storage back pressure of 0.01-1 MPa is applied to the screw.

6. The method for preparing a molded self-lubricating sliding bearing gasket according to any one of claims 1 to 4, wherein, In step 3), the mold clamping pressure is 30-100 MPa; and / or The vacuum level during mold closing is 0.01 MPa; and / or The screw speed during injection is 50-120 r / min; and / or The injection pressure is 30-100 MPa; and / or The injection travel distance is 20-40 mm; and / or During injection, the screw advance speed is 20-200 mm / s; and / or The holding pressure is 5-15 MPa; and / or The screw speed is 10-300 r / min during pressure holding.

7. The method for preparing a molded self-lubricating sliding bearing gasket according to any one of claims 1 to 4, wherein, In step 4), the mold heating temperature is 100-130℃; and / or The mold heating time is 10-20 minutes; and / or The mold opening speed is 1-200 mm / s; and / or The ejection speed when ejecting the product is 1-100mm / s.

8. The method for preparing a molded self-lubricating sliding bearing gasket according to any one of claims 1 to 4, wherein, In the method, the barrel, mold, and screw section are each connected to a chiller; Optionally, the temperature of the cooling water in the chiller is 0-20°C.

9. An injection mold for preparing a molded self-lubricating sliding bearing bushing, the mold comprising at least: Bearing positioning structure, used to position the inner and outer rings of the bearing; The cooling system includes a multi-loop parallel cooling water channel for cooling the mold and the flow channels within the mold; The heating and temperature control system is used to heat and solidify the material injected into the bearing, and to measure and control the internal temperature of the mold in real time.

10. The injection mold for preparing a molded self-lubricating sliding bearing bushing according to claim 9, wherein, The bearing positioning structure is located at the center of the mold; and / or The cooling water channel is connected to a chiller; and / or The heating temperature of the heating and temperature control system shall not be lower than 200℃.

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