Forming process of high-wear-resistance valve seat of drilling and production mud pump

Abstract

The application relates to the technical field of oil drilling and production machinery accessory manufacturing, and discloses a forming process of a high-wear-resistance drilling and production mud pump valve seat, which comprises the following steps: dehydrating hydroxyl-terminated polybutadiene and adding hexagonal boron nitride powder to obtain a suspension slurry; adding a pure 1,5-naphthalene diisocyanate monomer for grafting reaction to obtain a reactive slurry; dynamically mixing the reactive slurry, NDI-polyethylene glycol adipate pre-polymer and liquid hydroquinone dihydroxyethyl ether to obtain a homogeneous mixed liquid; injecting the homogeneous mixed liquid into a cavity of a built-in steel framework mud pump valve seat metal mold, maintaining pressure, applying vacuum in the early stage of pressure maintaining, applying positive pressure in the later stage of pressure maintaining to obtain an initial solidification product; and heating, constant-temperature heat preservation and demolding are carried out on the initial solidification product. The application solves the micro-compatibility defect through grafting modification, the internal bubbles are discharged and the occlusion area is increased by alternately applying vacuum and positive pressure, and the three-dimensional network structure is perfected through constant-temperature heat preservation.

Description

Technical Field

[0001] This invention relates to the field of oil drilling and production machinery parts manufacturing technology, specifically a molding process for a high wear-resistant drilling mud pump valve seat. Background Technology

[0002] In oil drilling operations, mud pump valve seats need to withstand high-frequency alternating load impacts in mud containing solid particles. The interior of a mud pump valve seat typically comprises a metal skeleton and a polyurethane elastomer coating. Conventional polyurethane elastomer materials exhibit a high coefficient of surface friction and insufficient bulk wear resistance when subjected to mud containing solid particles, resulting in weak resistance to hydromechanical impacts. Furthermore, microcompatibility defects exist between the polar system of conventional polyurethane elastomers and the introduced non-polar modified components, leading to a decrease in the overall mechanical properties of the polyurethane material.

[0003] During the casting process of mud pump valve seats, air bubbles are easily incorporated into the polyurethane mixture, forming stress concentration sources within the polyurethane matrix. Conventional molding processes result in low penetration of the polyurethane material into the micropores of the metal skeleton surface, leading to a small physical-mechanical interlocking area at the multiphase material interface. Under prolonged mechanical and fluid impact, the interface between the internal metal skeleton and the polyurethane material is prone to delamination.

[0004] Conventional thermosetting molding processes often create temperature differences between the surface and core of the initially cured product during the heating and curing stage, generating thermal stress within the product. Without prolonged controlled constant-temperature insulation, the chain extension and crosslinking reactions of residual isocyanate groups within the polyurethane system are insufficient, and the three-dimensional network structure of the polymer is not fully developed. This results in the surface hardness and compressive strength of the mud pump valve seat failing to reach a stable state. Internal thermal stress and the imperfect three-dimensional network structure increase the risk of physical damage to the mud pump valve seat during high-temperature demolding. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a molding process for a high-wear-resistant drilling mud pump valve seat, which solves the problems of insufficient wear resistance due to poor microcompatibility of polyurethane materials in conventional mud pump valve seats, delamination of the metal skeleton bonding surface caused by air bubbles mixed in during the molding process, and demolding damage to the mud pump valve seat due to insufficient thermosetting crosslinking.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a molding process for a high wear-resistant drilling mud pump valve seat, comprising the following steps: After dehydrating hydroxyl-terminated polybutadiene in a reactor, dried hexagonal boron nitride powder was added and mixed under high shear to obtain a suspension slurry. The heated graft was injected into a suspension slurry with pure 1,5-naphthalene diisocyanate monomer, stirred to react, and then cooled to obtain a reactive slurry. The heated NDI-polyethylene adipate prepolymer, the heated liquid hydroquinone dihydroxyethyl ether, and the reactive slurry are pumped into the dynamic mixing head of a polyurethane casting machine and mixed to obtain a homogeneous mixture. The homogeneous mixture is injected into the temperature-controlled metal mold cavity of the built-in steel skeleton mud pump valve seat, and pressure is maintained. A vacuum is applied to the metal mold cavity of the built-in steel skeleton mud pump valve seat in the first part of the pressure maintenance, and a positive pressure is applied to the metal mold cavity of the built-in steel skeleton mud pump valve seat in the second part of the pressure maintenance to obtain the initial solidified product. The metal mold for the mud pump valve seat with an internal steel frame, along with the initially cured product, is heated and kept at a constant temperature. After cooling, the mold is demolded to obtain a high wear-resistant drilling mud pump valve seat.

[0007] By adopting the above technical solution, the reaction mechanism and innovation of this invention are described as follows: By pre-reacting hydroxyl-terminated polybutadiene with pure 1,5-naphthalene diisocyanate, the isocyanate group in the NDI-polyethylene adipate prepolymer molecule is chemically grafted onto the hydroxyl groups at the end of the hydroxyl-terminated polybutadiene. Due to the good flexibility and low-temperature adaptability of the hydroxyl-terminated polybutadiene, the grafted product acts as a chemical linker between the inorganic filler (hexagonal boron nitride) and the polyurethane matrix.

[0008] Hexagonal boron nitride powder possesses excellent thermal conductivity and self-lubricating properties, but it is extremely difficult to disperse directly in a polyurethane matrix. This process first utilizes the low viscosity of hydroxyl-terminated polybutadiene to uniformly encapsulate and disperse the hexagonal boron nitride powder in a suspension slurry through high shear force. During the subsequent molding process, the hexagonal boron nitride, along with the grafted product, participates in the construction of the polyurethane skeleton, effectively preventing filler sedimentation and aggregation, thereby significantly reducing frictional heat generation during dynamic compression.

[0009] During the mold holding pressure process, a strategy of vacuum in the first stage and positive pressure in the second stage is adopted. Applying vacuum in the first stage of holding pressure can completely eliminate the trace air bubbles entrained during the casting process and the residual volatiles generated by the material reaction; applying positive pressure in the second stage of holding pressure compensates for the volume shrinkage of polyurethane during the curing reaction process, ensuring a tight physical bond between the polyurethane material and the built-in steel skeleton, and eliminating gaps at the bonding interface.

[0010] Therefore, a mud pump valve seat with extremely high wear resistance, excellent heat dissipation performance and high interfacial bonding strength is obtained.

[0011] Preferably, the amounts of each component, by mass, are as follows: Hydroxyl-terminated polybutadiene 5-15 parts; hexagonal boron nitride powder 2-8 parts; NDI-polyethylene adipate prepolymer 90-110 parts; liquid hydroquinone dihydroxyethyl ether 8-12 parts.

[0012] By adopting the above technical solution and strictly limiting the proportions of each component, the concentration of the reactive slurry in the homogeneous mixture can be ensured to be within the optimal range. Excessive hydroxyl-terminated polybutadiene content will reduce the material's hardness, while insufficient content will prevent adequate coating of hexagonal boron nitride. The hard segment structure formed by the NDI-polyethylene adipate prepolymer and liquid hydroquinone dihydroxyethyl ether provides the necessary rigid support for the valve seat.

[0013] Preferably, the conditions for dehydrating the hydroxyl-terminated polybutadiene in the reactor are: dehydration at 105-115°C and absolute pressure of -0.092 to -0.098 MPa for 1-3 hours; and the hexagonal boron nitride powder is dried at 145-155°C for 3-5 hours before being added.

[0014] By adopting the above technical solution, the moisture in the raw materials is completely removed, preventing trace amounts of moisture from reacting with isocyanate to produce carbon dioxide bubbles, thus ensuring the tightness of the internal structure of the valve seat.

[0015] Preferably, the specific method for obtaining the suspension slurry is as follows: turn on the high shear disperser and perform high shear mixing at a speed of 2500-3500 rpm for 10-30 minutes, and adjust the temperature of the reactor jacket to be constant at 85-95℃.

[0016] By adopting the above technical solution, under specific temperature and high shear conditions, the van der Waals aggregates of hexagonal boron nitride powder are broken by shear force, so that they can achieve a uniform dispersion state at the micron or even nanometer scale.

[0017] Preferably, the heating temperature for grafting pure 1,5-naphthalene diisocyanate monomer is 130-135°C; the molar amount of grafting pure 1,5-naphthalene diisocyanate monomer is 10%-15% of the molar equivalent of the terminal hydroxyl groups of polybutadiene.

[0018] By adopting the above technical solution, the monomer activity and ratio of NDI-polyethylene adipate prepolymer are controlled to ensure that only a portion of the isocyanate groups react with the hydroxyl-terminated polybutadiene, thus retaining sufficient active sites for copolymerization with the main chain prepolymer in subsequent stages.

[0019] Preferably, the specific method for obtaining the reactive slurry is as follows: inject the heated grafting pure 1,5-naphthalene diisocyanate monomer into a high shear disperser at a speed of 2500-3500 rpm, stir and react for 25-35 minutes at 85-95℃ and an absolute pressure of -0.085 to -0.095 MPa, and then cool down to 82-88℃.

[0020] By adopting the above technical solution, the grafting reaction can be completed under negative pressure, which can simultaneously remove trace impurities in the reaction system. The cooling process helps to adjust the viscosity of the slurry so that it can be precisely matched with the pumping flow rate of the polyurethane unit.

[0021] Preferably, the heating temperature of the NDI-polyethylene adipate prepolymer is 95-105℃, and the heating temperature of the liquid hydroquinone dihydroxyethyl ether is 105-115℃; when obtaining a homogeneous mixture, the rotation speed of the dynamic mixing head is 2500-3500 rpm, and the mixing time is 3-5 seconds.

[0022] By adopting the above technical solution, high-frequency collisions and uniform mixing of multi-component materials can be achieved in a very short time, ensuring the uniformity of molecular chain growth and avoiding uneven material properties caused by excessively rapid local reactions.

[0023] Preferably, when injecting the homogeneous mixture, the temperature of the metal mold cavity with the built-in steel skeleton mud pump valve seat is kept constant at 70-75℃; the pressure holding time is 12-20 minutes, wherein a vacuum of -0.05 to -0.08 MPa is applied to the metal mold cavity with the built-in steel skeleton mud pump valve seat for the first 2-5 minutes of pressure holding, and a positive pressure of 0.4-0.6 MPa is applied to the metal mold cavity with the built-in steel skeleton mud pump valve seat for the last 10-15 minutes of pressure holding.

[0024] By adopting the above technical solution, the initial temperature of the mold and the precise segmented pressure parameters are controlled. During the initial vacuum period, the window where the mixture has not yet lost its fluidity is used to eliminate tiny air pockets; during the subsequent positive pressure period, pressure is used to forcefully propel the mixture to fill every tiny dead corner of the mold, enhancing the anchoring force between the material and the steel frame.

[0025] Preferably, the heating and curing conditions for obtaining the high wear-resistant drilling mud pump valve seat are as follows: heating to 125-135℃ at a heating rate of 1-3℃ / minute, and maintaining the temperature at 125-135℃ for 10-14 hours.

[0026] By adopting the above technical solution, gradient heating can prevent internal stress concentration caused by excessive internal and external temperature differences, and long-term constant temperature insulation ensures that the polyurethane molecular chains are fully cross-linked, thus completing the construction of the microphase separation structure.

[0027] Preferably, after the constant temperature insulation is completed, the metal mold with built-in steel frame mud pump valve seat and the product are cooled to 75-85℃ for demolding.

[0028] By adopting the above technical solution, demolding is performed under an appropriate elastic modulus, avoiding geometric deformation caused by demolding at high temperatures, and ensuring that the dimensional and positional tolerances of the valve seat meet the requirements of precise drilling and production.

[0029] This invention provides a molding process for a high wear-resistant drilling mud pump valve seat. It has the following beneficial effects: 1. This invention modifies hydroxyl-terminated polybutadiene by grafting it with pure 1,5-naphthalene diisocyanate monomer, and disperses hexagonal boron nitride powder into the modified hydroxyl-terminated polybutadiene to form a reactive slurry. Subsequently, the reactive slurry is mixed and crosslinked with NDI-polyethylene adipate prepolymer and liquid hydroquinone dihydroxyethyl ether. This solves the microcompatibility defect between nonpolar hydrocarbon chains and polar polyurethane systems. The flexible segments provided by the hydroxyl-terminated polybutadiene absorb the impact energy of hydromechanical processes, and the hexagonal boron nitride powder constructs a solid lubrication interface inside the polyurethane elastomer matrix, reducing the surface friction coefficient of the high wear-resistant drilling mud pump valve seat when it is eroded by mud containing solid particles, thereby improving the wear resistance of the high wear-resistant drilling mud pump valve seat.

[0030] 2. This invention applies a vacuum during the initial pressure maintenance phase within the metal mold cavity of the built-in steel frame mud pump valve seat, and applies positive pressure during the later phase. The vacuum environment removes air bubbles mixed into the homogeneous mixture, eliminating stress concentration sources within the polyurethane matrix. The positive pressure causes the polyurethane mixture to penetrate into the pores on the surface of the built-in steel frame. The alternating negative and positive pressure increases the physical and mechanical interlocking area between the built-in steel frame and the polyurethane material interface, preventing internal metal delamination of the high-wear-resistant drilling mud pump valve seat under high-frequency alternating load impact, and improving the bonding strength of the multiphase materials.

[0031] 3. This invention heats the pre-cured product to the target temperature range at a set heating rate and then maintains it at a constant temperature for a long time. The controlled heating rate reduces the temperature difference between the surface and core of the pre-cured product, preventing the generation of internal thermal stress. The constant temperature maintenance process promotes the continued chain extension and cross-linking reaction of the residual isocyanate groups inside the polyurethane system, improving the three-dimensional network structure of the polymer. This stabilizes the surface hardness and compressive mechanical properties of the high wear-resistant drilling mud pump valve seat, reducing the risk of structural damage during the high-temperature demolding process of the finished product. Attached Figure Description

[0032] Figure 1 This is a graph showing the viscosity of the homogeneous mixture of the present invention as a function of time. Figure 2 This is a graph showing the relationship between the central temperature of the homogeneous mixture of the present invention and time. Figure 3 This is a graph showing the relationship between the center temperature and time during the dynamic compression process of the present invention; Figure 4 This is a graph showing the relationship between the amount of mass lost during rinsing and time, as presented in this invention. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to test examples. 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.

[0034] Examples 1-3: Example 1: This embodiment provides a molding process for a high wear-resistant drilling mud pump valve seat, including the following process steps: S1. Place 10 parts by mass of hydroxyl-terminated polybutadiene into a reactor and dehydrate it for 2 hours at 110°C and -0.095 MPa absolute pressure. Add 5 parts by mass of hexagonal boron nitride powder dried at 150°C for 4 hours to the dehydrated hydroxyl-terminated polybutadiene. Turn on the high shear disperser and mix at 3000 rpm for 20 minutes. Adjust the temperature of the reactor jacket to be constant at 90°C to obtain a suspension slurry. S2. Grafting pure 1,5-naphthalene diisocyanate monomer was placed in a heating tank and heated to 132°C. The molar amount of grafting pure 1,5-naphthalene diisocyanate monomer was 12% of the molar equivalent of the terminal hydroxyl groups of 10 parts by mass of terminal hydroxyl polybutadiene. The grafting pure 1,5-naphthalene diisocyanate monomer heated to 132°C was injected into the suspension slurry at a high shear dispersion speed of 3000 rpm. The mixture was stirred and reacted at 90°C and an absolute pressure of -0.090 MPa for 30 minutes. The mixture was then cooled to 85°C to obtain a reactive slurry. S3. 100 parts by mass of NDI-polyethylene adipate prepolymer heated to 100°C, 10 parts by mass of liquid hydroquinone dihydroxyethyl ether heated to 110°C, and reactive slurry are pumped into the dynamic mixing head of a polyurethane casting machine and mixed for 4 seconds at a speed of 3000 rpm in the dynamic mixing head to obtain a homogeneous mixture. S4. The homogeneous mixture was injected into the metal mold cavity of the built-in steel skeleton mud pump valve seat, which was kept at a constant temperature of 72°C. The pressure was maintained at 72°C for 15 minutes. During the first 3 minutes of the pressure maintenance, a vacuum of -0.06MPa was applied to the metal mold cavity of the built-in steel skeleton mud pump valve seat. During the last 12 minutes of the pressure maintenance, a positive pressure of 0.5MPa was applied to the metal mold cavity of the built-in steel skeleton mud pump valve seat, and the initial solidified product was obtained. S5. The metal mold with the built-in steel skeleton mud pump valve seat, together with the pre-cured product, is heated to 130°C at a heating rate of 2°C / minute. It is kept at 130°C for 12 hours and then cooled to 80°C to demold, thus obtaining a high wear-resistant drilling mud pump valve seat.

[0035] Example 2: This embodiment provides a molding process for a high wear-resistant drilling mud pump valve seat, including the following process steps: S1. Place 15 parts by mass of hydroxyl-terminated polybutadiene into a reactor and dehydrate it for 3 hours at 115°C and -0.098 MPa absolute pressure. Add 8 parts by mass of hexagonal boron nitride powder dried at 155°C for 5 hours to the dehydrated hydroxyl-terminated polybutadiene. Turn on the high shear disperser and mix at 3500 rpm for 30 minutes. Adjust the temperature of the reactor jacket to be constant at 95°C to obtain a suspension slurry. S2. Grafting pure 1,5-naphthalene diisocyanate monomer was placed in a heating tank and heated to 135°C. The molar amount of grafting pure 1,5-naphthalene diisocyanate monomer was 15% of the molar equivalent of the terminal hydroxyl groups of 15 parts by mass of terminal hydroxyl polybutadiene. The grafting pure 1,5-naphthalene diisocyanate monomer heated to 135°C was injected into the suspension slurry at a high shear dispersion speed of 3500 rpm. The mixture was stirred and reacted at 95°C and an absolute pressure of -0.095 MPa for 35 minutes. The mixture was then cooled to 88°C to obtain a reactive slurry. S3. 110 parts by mass of NDI-polyethylene adipate prepolymer heated to 105°C, 12 parts by mass of liquid hydroquinone dihydroxyethyl ether heated to 115°C, and reactive slurry were pumped into the dynamic mixing head of a polyurethane casting machine and mixed for 5 seconds at a speed of 3500 rpm in the dynamic mixing head to obtain a homogeneous mixture. S4. The homogeneous mixture was injected into the metal mold cavity with a built-in steel skeleton mud pump valve seat, which was kept at a constant temperature of 75°C. The pressure was maintained at 75°C for 20 minutes. During the first 5 minutes of the 20-minute pressure maintenance, a vacuum of -0.08 MPa was applied to the metal mold cavity with a built-in steel skeleton mud pump valve seat. During the last 15 minutes of the 20-minute pressure maintenance, a positive pressure of 0.6 MPa was applied to the metal mold cavity with a built-in steel skeleton mud pump valve seat, and the initial solidified product was obtained. S5. The metal mold with the built-in steel skeleton mud pump valve seat, together with the pre-cured product, is heated to 135°C at a heating rate of 3°C / minute. It is kept at 135°C for 14 hours and then cooled to 85°C to demold, thus obtaining a high wear-resistant drilling mud pump valve seat.

[0036] Example 3: This embodiment provides a molding process for a high wear-resistant drilling mud pump valve seat, including the following process steps: S1. Place 5 parts by mass of hydroxyl-terminated polybutadiene into a reactor and dehydrate it for 1 hour at 105°C and an absolute pressure of -0.092 MPa. Add 2 parts by mass of hexagonal boron nitride powder dried at 145°C for 3 hours to the dehydrated hydroxyl-terminated polybutadiene. Turn on the high shear disperser and mix at 2500 rpm for 10 minutes. Adjust the temperature of the reactor jacket to be constant at 85°C to obtain a suspension slurry. S2. Grafting pure 1,5-naphthalene diisocyanate monomer was placed in a heating tank and heated to 130°C. The molar amount of grafting pure 1,5-naphthalene diisocyanate monomer was 10% of the molar equivalent of 5 parts by mass of terminal hydroxyl polybutadiene. The grafting pure 1,5-naphthalene diisocyanate monomer heated to 130°C was injected into the suspension slurry at a high shear dispersion speed of 2500 rpm. The mixture was stirred and reacted at 85°C and an absolute pressure of -0.085 MPa for 25 minutes. The mixture was then cooled to 82°C to obtain a reactive slurry. S3. 90 parts by mass of NDI-polyethylene adipate prepolymer heated to 95°C, 8 parts by mass of liquid hydroquinone dihydroxyethyl ether heated to 105°C, and reactive slurry are pumped into the dynamic mixing head of a polyurethane casting machine and mixed for 3 seconds at a speed of 2500 rpm in the dynamic mixing head to obtain a homogeneous mixture. S4. The homogeneous mixture was injected into the metal mold cavity of the built-in steel skeleton mud pump valve seat, which was kept at a constant temperature of 70°C. The pressure was maintained at 70°C for 12 minutes. During the first 2 minutes of the pressure maintenance, a vacuum of -0.05MPa was applied to the metal mold cavity of the built-in steel skeleton mud pump valve seat. During the last 10 minutes of the pressure maintenance, a positive pressure of 0.4MPa was applied to the metal mold cavity of the built-in steel skeleton mud pump valve seat, and the initial solidified product was obtained. S5. The metal mold with the built-in steel skeleton mud pump valve seat, together with the pre-cured product, is heated to 125°C at a heating rate of 1°C / minute. It is kept at 125°C for 10 hours and then cooled to 75°C to demold, thus obtaining a high wear-resistant drilling mud pump valve seat.

[0037] Comparative Examples 1-5: Comparative Example 1: Compared with Example 1, the difference is that hydroxyl-terminated polybutadiene, hexagonal boron nitride powder, and pure 1,5-naphthalene diisocyanate monomer for grafting are not added, and steps S1 and S2 are not performed. In step S3, only 100 parts by weight of NDI-polyethylene adipate prepolymer heated to 100°C and 10 parts by weight of liquid hydroquinone dihydroxyethyl ether heated to 110°C are pumped into the dynamic mixing head of the polyurethane casting machine and mixed for 4 seconds at a speed of 3000 rpm in the dynamic mixing head to obtain a homogeneous mixture. In step S4, the homogeneous mixture is injected into the metal mold cavity of the built-in steel skeleton mud pump valve seat, which is kept at a constant temperature of 115°C. The pressure is maintained at 115°C for 15 minutes to obtain the initial cured product. The rest are the same.

[0038] Comparative Example 2: Compared with Example 1, the difference is that no grafting pure 1,5-naphthalene diisocyanate monomer is added, step S2 is not performed, and in step S3, 100 parts by mass of NDI-polyethylene adipate prepolymer heated to 100°C, 10 parts by mass of liquid hydroquinone dihydroxyethyl ether heated to 110°C, and the suspension slurry obtained in step S1 are pumped into the dynamic mixing head of the polyurethane casting machine and mixed for 4 seconds at a speed of 3000 rpm in the dynamic mixing head to obtain a homogeneous mixture. The rest are the same.

[0039] Comparative Example 3: Compared with Example 1, the difference is that in step S4, the homogeneous mixture is injected into the metal mold cavity of the built-in steel skeleton mud pump valve seat, which is kept at a constant temperature of 115°C, and maintained at atmospheric pressure at 115°C for 15 minutes. The operation of applying a vacuum of -0.06MPa and applying a positive pressure of 0.5MPa to the metal mold cavity of the built-in steel skeleton mud pump valve seat is not performed, and a preliminary solidified product is obtained. All other operations are the same.

[0040] Comparative Example 4: Compared with Example 1, the difference is that in step S2, the molar amount of pure 1,5-naphthalene diisocyanate monomer used for grafting is 100% of the molar equivalent of the terminal hydroxyl groups of 10 parts by mass of terminal hydroxyl polybutadiene, and all other aspects are the same.

[0041] Comparative Example 5: Compared with Example 1, the difference is that in step S4, the homogeneous mixture is injected into the metal mold cavity of the built-in steel skeleton mud pump valve seat, which is kept at a constant temperature of 72°C, and maintained at atmospheric pressure at 72°C for 15 minutes. The operation of applying a vacuum of -0.06MPa and applying a positive pressure of 0.5MPa to the metal mold cavity of the built-in steel skeleton mud pump valve seat is not performed, and the initial solidified product is obtained. All other operations are the same.

[0042] Test Examples 1-6: Test Example 1: This test example provides a macroscopic phase stability and viscosity mutation test for the homogeneous mixtures obtained in step S3 of Examples 1 to 3, Comparative Examples 2 and 4. The test includes the following steps: The homogeneous mixture discharged from the dynamic mixing head of the polyurethane casting machine is intercepted.

[0043] The homogeneous mixture was injected into a graduated glass cylinder at a constant temperature of 90°C and kept still for 15 minutes. The volume of the liquid hydroxyl-terminated polybutadiene precipitated on the upper layer of the glass cylinder was read, and the percentage of the liquid hydroxyl-terminated polybutadiene volume to the total volume of the homogeneous mixture was calculated to obtain the phase separation percentage after 15 minutes.

[0044] Inject the homogeneous mixture into the test chamber of the rotational viscometer, set the temperature of the test chamber of the rotational viscometer to 90℃, start the rotational viscometer, and record the viscosity values ​​of the homogeneous mixture at the initial 0 minutes, 10 minutes, 20 minutes, and 30 minutes.

[0045] Table 1. Macroscopic phase separation percentage and viscosity of homogeneous mixtures over time. Figure 1 This is a graph showing the viscosity of the homogeneous mixture of the present invention as a function of time. Figure 1 The horizontal axis represents time, with units in minutes, and the vertical axis represents viscosity, with units in mPas. Figure 1 It includes the corresponding viscosity test data points of Examples 1, 2, 3, Comparative Example 2, and 4, as well as the trend distribution of connecting the test data points into a line. Figure 1 The circular data points represent the viscosity changes in Example 1, the square data points represent the viscosity changes in Example 2, the triangular data points represent the viscosity changes in Example 3, the rhomboid data points represent the viscosity changes in Comparative Example 2, and the star-shaped data points represent the viscosity changes in Comparative Example 4.

[0046] Refer to Table 1 and Figure 1 It was found that the 15-minute phase separation percentage of Comparative Example 2 was 12.4%, while the 15-minute phase separation percentages of Examples 1, 2, and 3 were all 0. Comparative Example 2 lacked pure 1,5-naphthalene diisocyanate monomer for grafting. There was thermodynamic incompatibility between the polar NDI-polyethylene adipate prepolymer and the nonpolar hydroxyl-terminated polybutadiene. During the static settling of the homogeneous mixture, the hydroxyl-terminated polybutadiene underwent oil phase floating and aggregation, resulting in liquid-liquid phase separation.

[0047] In Examples 1, 2, and 3, pure 1,5-naphthalene diisocyanate monomer for grafting was added. The pure 1,5-naphthalene diisocyanate monomer for grafting consumed some of the terminal hydroxyl groups of the terminal hydroxyl polybutadiene, generating block oligomers with isocyanate end groups. After the block oligomers entered the homogeneous mixture, the isocyanate end groups interacted with the NDI-polyethylene adipate prepolymer, preventing the terminal hydroxyl polybutadiene from agglomerating into macroscopic large droplets, avoiding phase separation in the homogeneous mixture, and maintaining the physical homogeneity of the homogeneous mixture.

[0048] The viscosity of Comparative Example 4 reached 28,400 mPas after 30 minutes, while that of Example 1 was 5,891 mPas. In Comparative Example 4, the molar amount of pure 1,5-naphthalene diisocyanate monomer used for grafting reached 100% of the molar equivalent of the terminal hydroxyl groups in the polybutadiene. The terminal hydroxyl polybutadiene was completely capped by the grafted pure 1,5-naphthalene diisocyanate monomer. The completely capped terminal hydroxyl polybutadiene became a high-functionality crosslinking center, which promoted an early chemical gelation reaction in the homogeneous mixture within 30 minutes, resulting in a sudden increase in viscosity that disrupted the operating window.

[0049] In Example 1, the amount of pure 1,5-naphthalene diisocyanate monomer used for grafting was limited to a preset molar equivalent ratio. The hydroxyl-terminated polybutadiene maintained a unilateral grafting state. This unilateral grafting state limited the three-dimensional crosslinking expansion rate of the spatial network, keeping the viscosity increase of the homogeneous mixture gradual and allowing sufficient flow time for subsequent injection into the metal mold cavity. Comprehensive comparisons demonstrate that controlling the preset ratio of pure 1,5-naphthalene diisocyanate monomer for grafting can utilize the chemical bonding of existing substances to intervene in the molecular network construction, solve the problem of layering in the blending of non-polar substances, and maintain the viscosity rheological properties required for the molding process.

[0050] Test Example 2: This test example provides tests conducted on the thermodynamic exothermic peak values ​​at the molding center in Examples 1 to 3 and Comparative Example 3. The tests include the following steps: A thermocouple temperature probe is fixed at the geometric center of the metal mold cavity of the built-in steel frame mud pump valve seat.

[0051] The homogeneous mixture discharged from the dynamic mixing head of the polyurethane casting machine is injected into the metal mold cavity with a built-in steel skeleton mud pump valve seat.

[0052] Starting from the moment the homogeneous mixture is injected, the temperature values ​​of the geometric center of the metal mold cavity with the built-in steel skeleton mud pump valve seat are recorded at 0 minutes, 3 minutes, 6 minutes, 9 minutes, 12 minutes, and 15 minutes using a thermocouple temperature probe.

[0053] Table 2. Data on the change of central temperature of homogeneous mixture over time. Figure 2 This is a graph showing the relationship between the central temperature of the homogeneous mixture of the present invention and time. Figure 2 The horizontal axis represents time, with units in minutes, and the vertical axis represents temperature, with units in degrees Celsius (°C). Figure 2 It includes the corresponding temperature test data points of Examples 1, 2, 3 and Comparative Example 3, as well as the trend distribution of connecting the test data points into a line. Figure 2The circular data points represent the temperature changes in Example 1, the square data points represent the temperature changes in Example 2, the triangular data points represent the temperature changes in Example 3, and the diamond-shaped data points represent the temperature changes in Comparative Example 3.

[0054] Refer to Table 2 and Figure 2 It was found that the temperature at the geometric center of the metal mold cavity with the built-in steel skeleton mud pump valve seat in Comparative Example 3 reached 142.7°C after 9 minutes. The highest temperature at the geometric center of the metal mold cavity with the built-in steel skeleton mud pump valve seat in Example 1 was 102.1°C after 3 minutes. In Comparative Example 3, the metal mold cavity with the built-in steel skeleton mud pump valve seat was kept at a constant temperature of 115°C. The NDI-polyethylene adipate prepolymer and liquid hydroquinone dihydroxyethyl ether underwent a crosslinking reaction within the metal mold cavity with the built-in steel skeleton mud pump valve seat, releasing heat of reaction. The metal mold cavity with the built-in steel skeleton mud pump valve seat, kept at a constant temperature of 115°C, did not have the temperature difference to absorb the heat of reaction. The heat of reaction accumulated continuously at the center of the homogeneous mixture, causing the center temperature to rise continuously. The excessively high center temperature triggered the physical loss of hydrogen bonds within the polyurethane network and localized thermal degradation.

[0055] In Examples 1, 2, and 3, the metal mold cavity of the built-in steel-framed mud pump valve seat was kept at a constant temperature between 70°C and 75°C. This constant temperature range, relative to the homogeneous mixture at approximately 100°C during injection, created a physical heat sink. The reaction heat released by the homogeneous mixture was driven by the temperature difference to conduct to the metal wall of the mold cavity. The outward conduction of heat offset the accumulated heat generated by the crosslinking reaction, suppressing the temperature peak at the geometric center of the mold cavity to below 107°C. This prevented thermal degradation at the center of the homogeneous mixture, ensuring the uniformity of the crosslinking density of the macromolecules within and outside the high-wear-resistant drilling mud pump valve seat. This demonstrates the suppressive effect of the variable-temperature molding process on the exothermic deformation problem of thick-walled polyurethane parts.

[0056] Test Example 3: This test example provides material apparent density and macroscopic compactness tests on the high wear-resistant drilling mud pump valve seats obtained in Examples 1 to 3 and Comparative Example 5. To increase the objectivity of the test data, three high wear-resistant drilling mud pump valve seat samples were prepared and cut for each group. The test includes the following steps: The high wear-resistant drilling mud pump valve seat obtained after demolding was selected as the test sample.

[0057] The volume and mass of the test sample were determined using the Archimedes displacement method. The apparent density was obtained by dividing the measured mass value by the measured volume value.

[0058] The test sample is cut along the central axis to obtain the cross-section. A penetrant is sprayed onto the cross-section, and the area of ​​the macropores is recorded. The percentage of the macropore area is obtained by dividing the macropore area by the total area of ​​the cross-section.

[0059] Table 3. Test data on apparent density and percentage of macroscopic pore area of ​​valve seat for high wear-resistant drilling mud pump. Referring to Table 3, the test sample of Comparative Example 5 has a concentration between 1.179 g / cm³. 3 Up to 1.185 g / cm 3 The apparent density and the percentage of macroscopic pore area were between 3.15% and 3.87%. The apparent density of the test samples in Examples 1, 2, and 3 were all greater than 1.240 g / cm³. 3 Furthermore, the percentage of macroscopic pore area was 0%. In Comparative Example 5, the pressure was maintained at normal pressure within the metal mold cavity of the built-in steel skeleton mud pump valve seat. During the isothermal curing process, the NDI-polyethylene adipate prepolymer in the homogeneous mixture reacted with trace amounts of moisture in the system to produce carbon dioxide gas. At the same time, the air entrained in the homogeneous mixture under the high-speed stirring of the dynamic mixing head could not be spontaneously discharged during the viscosity increase stage. Under normal pressure conditions, the gas remained in the cured polyurethane network, forming macroscopic pores and reducing the apparent density of the material. Examples 1, 2, and 3 involved a pressure-variable operation: first applying a vacuum to the metal mold cavity of the built-in steel-framed mud pump valve seat, followed by applying positive pressure. Applying vacuum during the initial curing stage, when the homogeneous mixture has low viscosity, increases the pressure difference between the inside and outside of the homogeneous mixture. This causes microbubbles within the mixture to migrate to the surface and rupture, eliminating gases generated by side reactions and mechanically entrained air. The subsequent application of positive pressure compresses the free volume within the cross-linked network, forcing any remaining micro-gases to redissolve into the polyurethane matrix, thus limiting bubble expansion. This pressure-variable operation eliminates the macroscopic porosity within the cured product, improving the macroscopic compactness and apparent density of the high-wear-resistant drilling mud pump valve seat.

[0060] Test Example 4: This test example provides a dynamic compression hysteresis heat generation performance test of the high wear-resistant drilling mud pump valve seats obtained in Examples 1 to 3, Comparative Examples 1 and 3. The test includes the following steps: Standard cylindrical samples were cut from the high wear-resistant drilling mud pump valve seat obtained after demolding.

[0061] A hole was drilled at the geometric center of a standard cylindrical specimen and a temperature probe was pre-embedded.

[0062] A standard cylindrical specimen with a temperature probe is installed in the test chamber of a compression heat generation tester. The compression heat generation tester is set to apply a dynamic reciprocating compression fatigue load with a constant frequency and a constant compression deformation rate to the standard cylindrical specimen.

[0063] The dynamic compression heat generation tester reads and records the temperature values ​​of the geometric center position of a standard cylindrical specimen at 0 minutes, 10 minutes, 20 minutes, and 30 minutes during the continuous execution of dynamic reciprocating compression fatigue load.

[0064] Table 4. Data on the change of center temperature of valve seat of high wear-resistant drilling mud pump over time during dynamic compression process. Figure 4 This is a graph showing the relationship between the center temperature of the valve seat of the high wear-resistant drilling mud pump of the present invention and time during the dynamic compression process. Figure 4 The horizontal axis represents time, with units in minutes, and the vertical axis represents temperature, with units in degrees Celsius (°C). Figure 4 It includes the corresponding test data points of Examples 1, 2, and 3, Comparative Example 1 and Comparative Example 3, as well as the trend distribution of connecting the test data points into a line. Figure 4 The circular data points represent the test sample distribution of Example 1, the square data points represent the test sample distribution of Example 2, the triangular data points represent the test sample distribution of Example 3, the pentagonal data points represent the test sample distribution of Comparative Example 1, and the rhombus data points represent the test sample distribution of Comparative Example 3.

[0065] Refer to Table 4 and Figure 3 It was found that the temperature of Comparative Example 1 rose to 71.3℃ after 30 minutes, while the temperatures of Examples 1, 2, and 3 remained within the range of 40.8℃ to 43.5℃ after 30 minutes. No hydroxyl-terminated polybutadiene or hexagonal boron nitride powder was added during the preparation process of Comparative Example 1. When subjected to dynamic reciprocating compressive fatigue loads, the molecular chain segments within the polyurethane network undergo relative slippage and generate internal friction, which converts the input mechanical energy into heat energy. The high-wear-resistant drilling mud pump valve seat of Comparative Example 1 lacks a physical heat conduction path, causing the converted heat energy to accumulate at the geometric center of the valve seat, resulting in a continuous increase in the center temperature.

[0066] In Examples 1, 2, and 3, hydroxyl-terminated polybutadiene and hexagonal boron nitride powder were added in predetermined mass proportions. The hydroxyl-terminated polybutadiene, as a flexible soft segment structure, was incorporated into the main chain of the polyurethane network. The flexible segments provided by the hydroxyl-terminated polybutadiene reduced the internal frictional resistance of the polyurethane network during compression deformation, thereby reducing the conversion of mechanical energy into thermal energy at the source. The hexagonal boron nitride powder, also in predetermined mass proportions, was dispersed and in contact with each other within the polyurethane network. This hexagonal boron nitride powder constructed a physical heat conduction path connecting the inside and outside of the high-wear-resistant drilling mud pump valve seat. This physical heat conduction path transferred the residual heat generated by the polyurethane network to the surface of the high-wear-resistant drilling mud pump valve seat, preventing heat accumulation at the geometric center.

[0067] The temperature of Comparative Example 3 reached 64.9℃ after 30 minutes. Comparative Example 3 was subjected to atmospheric pressure maintenance operation at 115℃. The 115℃ mold environment hindered the outward conduction of the latent heat released by the crosslinking reaction. This latent heat disrupted the orderly arrangement of hydrogen bonds within the polyurethane network, leading to non-uniform local network defects inside the valve seat of the high-wear-resistant drilling mud pump in Comparative Example 3. These local network defects induced stress concentration under dynamic reciprocating compressive fatigue loads. This stress concentration increased the frequency of friction between molecular chain segments in the defect area, thus increasing the local frictional heat generation.

[0068] Examples 1, 2, and 3 employed a mold temperature of 70°C to 75°C combined with a variable pressure process. The cold mold heat sink mechanism, combined with variable pressure venting, eliminated structural defects within the polyurethane network, maintained a uniform arrangement of hydrogen bonds, avoided additional heat generation caused by stress concentration, and ensured the thermodynamic stability of the high-wear-resistant drilling mud pump valve seat under continuous high-frequency compression conditions.

[0069] Test Example 5: This test example provides a fluid sand-carrying erosion wear test on the high wear-resistant drilling mud pump valve seats obtained in Examples 1 to 3, Comparative Examples 1 and 4. The test includes the following steps: Standard-sized samples were cut from the high wear-resistant drilling mud pump valve seat obtained after demolding, and the initial mass of the standard-sized samples was weighed. The initial mass was recorded as 100 parts by mass.

[0070] Standard-sized specimens are installed in the test fixture of a high-pressure fluid scouring test bench containing fixed nozzles. A water-based fluid containing standard-size quartz sand is prepared and injected into the storage tank of the high-pressure fluid scouring test bench.

[0071] The high-pressure fluid scouring test bench is set to maintain a constant spray pressure, and the spray angle of the fixed nozzle is adjusted to 45 degrees. Water-based fluid is used to perform continuous scouring on the surface of a standard-sized sample.

[0072] The high-pressure fluid scouring test bench was paused at 6, 12, 18 and 24 hours after the scouring operation was completed. The standard-sized sample was removed and dried. The remaining mass of the dried standard-sized sample was weighed and recorded as the remaining mass fraction value. The scouring mass fraction loss at the corresponding time point was obtained by subtracting the remaining mass fraction value from 100 mass fractions.

[0073] Table 5. Data on the change of mass loss due to erosion of valve seat in high wear-resistant drilling mud pump over time. Example 1 0.51 0.98 1.42 1.84 Example 2 0.43 0.85 1.27 1.62 Example 3 0.62 1.15 1.68 2.15 Comparative Example 1 1.85 4.12 6.45 8.73 Comparative Example 4 1.42 3.05 4.81 6.51 Figure 4 This is a graph showing the relationship between the erosion mass loss of the valve seat of the high wear-resistant drilling mud pump of the present invention and time. Figure 4 The horizontal axis represents time, with units in hours, and the vertical axis represents the amount of mass lost due to erosion, with units in parts by mass. Figure 4 It includes the corresponding test data points of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 4, as well as the trend distribution of connecting the test data points into a line. Figure 4 The circular data points represent the test sample distribution of Example 1, the square data points represent the test sample distribution of Example 2, the triangular data points represent the test sample distribution of Example 3, the pentagram data points represent the test sample distribution of Comparative Example 1, and the right-pointing triangle data points represent the test sample distribution of Comparative Example 4. Refer to Table 5 and Figure 4 It was found that the 24-hour scouring mass loss in Comparative Example 1 reached 8.73 parts by mass. Comparative Example 1 lacked hydroxyl-terminated polybutadiene and hexagonal boron nitride powder. The valve seat surface of the high wear-resistant drilling mud pump in Comparative Example 1 directly rubbed against standard-size quartz sand in the water-based fluid. Under the continuous impact of constant high-pressure water-based fluid, the polyurethane cross-linked network underwent localized mechanical tearing, causing the matrix material to peel off and resulting in a high scouring mass loss.

[0074] The 24-hour scouring loss in Examples 1, 2, and 3 ranged from 1.62 to 2.15 parts by mass. The formulations of Examples 1, 2, and 3 included predetermined amounts of hydroxyl-terminated polybutadiene and hexagonal boron nitride powder. The hexagonal boron nitride powder formed solid lubrication nodes in the polyurethane crosslinking network, reducing the physical friction coefficient between the high-wear-resistant drilling mud pump valve seat surface and standard-size silica sand, thus weakening the cutting effect of the standard-size silica sand on the surface structure. The hydroxyl-terminated polybutadiene introduced flexible polybutadiene segments, which increased the elastic deformation capacity of the polyurethane crosslinking network against external impacts. The polyurethane crosslinking network absorbed the kinetic energy generated by the impact of the standard-size silica sand through its own macroscopic elastic deformation, delaying the propagation of microcracks within the polyurethane crosslinking network and reducing the final amount of material lost.

[0075] The 24-hour scouring loss in Comparative Example 4 was 6.51 parts by mass. In Comparative Example 4, the molar amount of the grafted pure 1,5-naphthalene diisocyanate monomer reached 100% of the molar equivalent of the terminal hydroxyl groups in the polybutadiene. The grafted pure 1,5-naphthalene diisocyanate monomer formed a completely sealed state on the terminal hydroxyl polybutadiene. This complete sealing state caused the terminal hydroxyl polybutadiene to become a multifunctional rigid crosslinking center and integrate into the polyurethane crosslinking network. The rigid crosslinking center spatially restricted the free displacement space of the flexible polybutadiene segments, reducing the overall elastic deformation limit of the polyurethane crosslinking network. Under continuous high-frequency impact from water-based fluids and standard-size quartz sand, the polyurethane crosslinking network inside the valve seat of the high-wear-resistant drilling mud pump in Comparative Example 4 lacked a mechanism for dissipating impact kinetic energy through chain segment slippage, leading to brittle fracture characteristics and increased scouring loss.

[0076] Examples 1, 2, and 3 employed a grafting process with a preset molar ratio, maintaining the single-end free overhang conformation of the hydroxyl-terminated polybutadiene. This single-end free conformation preserves the three-dimensional freedom of movement of the flexible polybutadiene segments, balancing the compatibility and stability of nonpolar hydroxyl-terminated polybutadiene in polar NDI-polyethylene adipate prepolymer with the impact-resistant energy dissipation mechanism of the polyurethane crosslinked network after molding, thus preventing excessive wear of the high-wear-resistant drilling mud pump valve seat during use.

[0077] Test Example 6: This test example provides a simulated high-frequency impact fatigue life test of the high wear-resistant drilling mud pump valve seats obtained in Examples 1 to 3 and Comparative Examples 1 to 5. The test includes the following steps: The high wear-resistant drilling mud pump valve seat obtained after demolding was installed on the test station of the mud pump valve group simulation test bench.

[0078] Water-based test medium was injected into the hydraulic system of the mud pump valve group simulation test bench. The system test pressure of the mud pump valve group simulation test bench was set to be constant at 35MPa, and the high-frequency reciprocating impact frequency was set to 120 times / minute.

[0079] The mud pump valve assembly simulation test bench was started to perform continuous high-frequency reciprocating impact tests on the valve seat of the high wear-resistant drilling mud pump.

[0080] Every 2 hours, pause the mud pump valve group simulation test bench to check whether macroscopic cracking or peeling occurs on the surface of the high wear-resistant drilling mud pump valve seat, and record the total number of cyclic impacts when the mud pump valve group simulation test bench shows a pressure holding failure prompt.

[0081] Table 6. High-frequency impact fatigue life test data of valve seats for high wear-resistant drilling mud pumps Referring to Table 6, the total number of cyclic impacts in Comparative Example 1 was 124,350. Comparative Example 1 did not contain terminal hydroxyl polybutadiene or hexagonal boron nitride powder, and its formulation was molded at 115°C and atmospheric pressure. The high-wear-resistant drilling mud pump valve seat in Comparative Example 1 exhibited thermal degradation and macroscopic pores. Furthermore, the polyurethane crosslinking network lacked flexible polybutadiene segments that dissipate mechanical energy, leading to fatigue cracking and pressure-holding failure of the high-wear-resistant drilling mud pump valve seat under continuous impact.

[0082] The total number of cyclic impacts in Comparative Example 2 was 108,620. Comparative Example 2 lacked pure 1,5-naphthalene diisocyanate monomer for grafting, resulting in liquid-liquid phase separation in the homogeneous mixture. This liquid-liquid phase separation created a structurally weak area inside the valve seat of the high-wear-resistant drilling mud pump. This weak area induced crack propagation under high-frequency reciprocating impact loads, reducing the impact cycle resistance of the high-wear-resistant drilling mud pump valve seat.

[0083] The total number of cyclic impacts in Comparative Example 3 was 156,740. Comparative Example 3 used a mold temperature of 115℃ and maintained at atmospheric pressure. The latent heat of reaction accumulated at the geometric center of the metal mold cavity containing the built-in steel skeleton mud pump valve seat. This accumulated latent heat caused thermodynamic degradation of the polyurethane cross-linked network, damaging the internal physical connection strength of the high-wear-resistant drilling mud pump valve seat, leading to premature failure of the valve seat.

[0084] The total number of cyclic impacts in Comparative Example 4 was 205,410. The grafting ratio in Comparative Example 4 reached 100% of the molar equivalent of the terminal hydroxyl groups in the polybutadiene. The fully sealed terminal hydroxyl polybutadiene forms a multifunctional rigid crosslinking center, which restricts the flexible displacement space of the polyurethane crosslinking network. Under high-frequency reciprocating impact loads, the rigid polyurethane crosslinking network lacks a physical dissipation mechanism for absorbing impact kinetic energy through chain segment slippage, causing brittle fracture of the valve seat of the high-wear-resistant drilling mud pump.

[0085] The total number of cyclic impacts in Comparative Example 5 was 182,170. Comparative Example 5 was subjected to pressure holding at normal pressure, resulting in the formation of a macroscopic pore structure inside the valve seat of the high-wear-resistant drilling mud pump. This macroscopic pore structure acted as a stress concentration trigger point, developing into a through-crack under the impact stress of the water-based test medium.

[0086] The total number of cyclic impacts in Examples 1, 2, and 3 ranged from 398,240 to 435,820. Examples 1, 2, and 3 incorporated predetermined amounts of hexagonal boron nitride powder and predetermined amounts of hydroxyl-terminated polybutadiene, and maintained the single-terminal free molecular conformation of the hydroxyl-terminated polybutadiene by grafting a predetermined molar equivalent of pure 1,5-naphthalene diisocyanate monomer.

[0087] Single-ended free polybutadiene flexible segments dissipate the mechanical kinetic energy generated by high-frequency impacts through three-dimensional elastic deformation, while the thermally conductive pathways constructed from a predetermined mass fraction of hexagonal boron nitride powder dissipate the heat energy generated by internal friction. Combined with a pressure-switching curing process at 70°C to 75°C, side reactions and bubbles introduced by stirring are eliminated, while simultaneously suppressing the peak value of crosslinking exothermic reactions. The aforementioned material formulation mechanism and the temperature-switching curing process ensure a uniform and highly dense polyurethane crosslinked network, preventing crack initiation and propagation in the high-wear-resistant drilling mud pump valve seat under high-pressure fluid impacts, and increasing the number of impact fatigue working cycles of the high-wear-resistant drilling mud pump valve seat under simulated working conditions.

Claims

1. A molding process for a high wear-resistant drilling mud pump valve seat, characterized in that, Includes the following steps: Hydroxyl-terminated polybutadiene is dehydrated in a reactor, and then dried hexagonal boron nitride powder is added and mixed under high shear to obtain a suspension slurry. Heated grafted pure 1,5-naphthalene diisocyanate monomer is injected into the suspension slurry, stirred, and cooled to obtain a reactive slurry. Heated NDI-polyethylene adipate prepolymer, heated liquid hydroquinone dihydroxyethyl ether, and the reactive slurry are pumped into the dynamic mixing head of a polyurethane casting machine and mixed to obtain a homogeneous mixture. The homogeneous mixture is injected into a thermostatically controlled metal mold cavity containing a built-in steel frame mud pump valve seat, and pressure is maintained. A vacuum is applied to the mold cavity during the initial pressure maintenance phase, and a positive pressure is applied during the subsequent pressure maintenance phase, resulting in a pre-cured product. The mold cavity, along with the pre-cured product, is then heated and kept at a constant temperature before being cooled and demolded, yielding a high-wear-resistant drilling mud pump valve seat.

2. The molding process for a high wear-resistant drilling mud pump valve seat according to claim 1, characterized in that, The amounts of each component, by mass, are as follows: 5-15 parts of the hydroxyl-terminated polybutadiene; 2-8 parts of the hexagonal boron nitride powder; 90-110 parts of the NDI-polyethylene adipate prepolymer; 8-12 parts of the liquid hydroquinone dihydroxyethyl ether.

3. The molding process for a high wear-resistant drilling mud pump valve seat according to claim 1, characterized in that, The conditions for dehydrating the hydroxyl-terminated polybutadiene in the reactor are as follows: Dehydrate for 1-3 hours at 105-115℃ and absolute pressure of -0.092 to -0.098 MPa; The hexagonal boron nitride powder is dried at 145-155°C for 3-5 hours before being added.

4. The molding process of a high wear-resistant drilling mud pump valve seat according to claim 1, characterized in that, The specific method for obtaining the suspended slurry is as follows: Turn on the high-shear disperser and perform the high-shear mixing at a speed of 2500-3500 rpm for 10-30 minutes, and adjust the temperature of the reactor jacket to be constant at 85-95℃.

5. The molding process for a high wear-resistant drilling mud pump valve seat according to claim 1, characterized in that, The heating temperature for the pure 1,5-naphthalene diisocyanate monomer used for grafting is 130-135℃; The molar amount of pure 1,5-naphthalene diisocyanate monomer used for grafting is 10%-15% of the molar equivalent of the terminal hydroxyl groups of the terminal hydroxyl polybutadiene.

6. The molding process for a high wear-resistant drilling mud pump valve seat according to claim 1, characterized in that, The specific method for obtaining the reactive slurry is as follows: The heated grafted pure 1,5-naphthalene diisocyanate monomer was injected into a high-shear disperser at a speed of 2500-3500 rpm, and the mixture was stirred and reacted for 25-35 minutes at 85-95℃ and an absolute pressure of -0.085 to -0.095 MPa, and then cooled to 82-88℃.

7. The molding process for a high wear-resistant drilling mud pump valve seat according to claim 1, characterized in that, The heating temperature of the NDI-polyethylene adipate prepolymer is 95-105℃, and the heating temperature of the liquid hydroquinone dihydroxyethyl ether is 105-115℃. When obtaining the homogeneous mixture, the rotation speed of the dynamic mixing head is 2500-3500 rpm, and the mixing time is 3-5 seconds.

8. The molding process for a high wear-resistant drilling mud pump valve seat according to claim 1, characterized in that, When the homogeneous mixture is injected, the metal mold cavity of the built-in steel skeleton mud pump valve seat is kept at a constant temperature of 70-75℃; The pressure holding time is 12-20 minutes, wherein a vacuum of -0.05 to -0.08 MPa is applied to the metal mold cavity of the built-in steel skeleton mud pump valve seat for the first 2-5 minutes of the pressure holding, and a positive pressure of 0.4-0.6 MPa is applied to the metal mold cavity of the built-in steel skeleton mud pump valve seat for the last 10-15 minutes of the pressure holding.

9. The molding process of a high wear-resistant drilling mud pump valve seat according to claim 1, characterized in that, The heating and curing conditions for obtaining the high wear-resistant drilling mud pump valve seat are as follows: heat to 125-135℃ at a heating rate of 1-3℃ / minute, and keep at a constant temperature of 125-135℃ for 10-14 hours.

10. The molding process of a high wear-resistant drilling mud pump valve seat according to claim 1, characterized in that, After completing the constant temperature insulation, the metal mold of the built-in steel frame mud pump valve seat and the product are cooled to 75-85℃ for demolding.

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