A buffer block for an air jacket in a pump, its preparation method and application

Abstract

This invention belongs to the field of buffer material technology, specifically disclosing a buffer block for a pump air bag, its preparation method, and its application. The raw materials for preparing the core layer of the buffer block include a polyurethane prepolymer and a chain extender composition A, and the raw materials for preparing the shell layer of the buffer block include a polyurethane prepolymer and a chain extender composition B. By weight, the chain extender composition A includes 60-80 parts of MOCA chain extender, 40-60 parts of hexanediol, 2-5 parts of epoxidized soybean oil, 3-5 parts of water, 0.5-1 parts of antioxidant, 0.5-2 parts of catalyst, and 0. 5-2.5 parts; Chain extender composition B includes 100-120 parts of MOCA chain extender, 10-15 parts of modified calcium carbonate whiskers, 1-1.5 parts of hydrolysis resistant agent, 0.5-1 part of antioxidant, 0.5-2 parts of catalyst and 0.5-2.5 parts of foam stabilizer. The buffer block as a whole can effectively stabilize the pressure, adapt to complex conveying media, and has excellent dynamic fatigue performance. Its application in the air jacket structure of mud pumps helps to effectively stabilize the pressure of mud pumps for a long time, and its application prospects are good.

Description

Technical Field

[0001] This invention belongs to the field of buffer material technology, and particularly relates to a buffer block for air jackets in pumps, its preparation method, and its application. Background Technology

[0002] Mud pumps typically employ a three-cylinder plunger pump design. A plunger pump is a reciprocating pump whose output pressure changes periodically during operation. Installing an air chamber at the mud pump outlet helps balance the peak pressure of the high-pressure fluid, stabilizing the pressure, reducing losses, and ensuring safety, thus achieving optimal suction performance. Conventional mud pump air chambers use a bladder-type structure, with a nitrogen-filled bladder inside. The expansion and contraction of the bladder buffers the high-pressure fluid pressure. This type of air chamber requires periodic inflation and bladder replacement, which is cumbersome for on-site workers, has high maintenance costs, and poor safety. To address these issues, a non-inflatable air chamber has been proposed in existing technology. This design offers significant advantages in terms of ease of maintenance, no need for inflation or bladder replacement, suppression of both flow pulsations and acceleration pulsations, long service life, and avoidance of the safety risks associated with inflation.

[0003] In the prior art, CN112283062A discloses a damper for a drilling mud pump, which uses a buffer liner inside the housing, and a buffer block assembly inside the buffer liner to achieve stable flow and pressure in the mud pump body. For this type of damper / airbag, the performance of the buffer blocks inside the structure is the key to its stable flow and pressure effect.

[0004] Polyurethane elastomers are widely used in buffer materials and other fields due to their excellent wear resistance, high strength, and excellent shock absorption properties. They are one of the commonly used materials for preparing buffer blocks. Currently, the most commonly used polyurethane elastomers on the market are MDI system polyurethane elastomers, which have excellent mechanical properties and good prepolymer stability, but have poor dynamic fatigue resistance. In view of the complex operating conditions and conveying media of mud pumps, developing buffer blocks with excellent mechanical properties and durability is an effective way to expand their application prospects in the field of mud pumps. In this regard, this invention proposes a buffer block for air jackets of pumps, its preparation method, and its application. Summary of the Invention

[0005] The purpose of this invention is to provide a buffer block for an air bag in a pump, its preparation method, and its application in order to solve the above-mentioned problems.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] As a first aspect of the present invention, a buffer block for an air jacket of a pump is provided, the buffer block having a core-shell structure. The raw materials for preparing the core layer of the buffer block include a polyurethane prepolymer and chain extender composition A, and the raw materials for preparing the shell layer of the buffer block include a polyurethane prepolymer and chain extender composition B; by weight...

[0008] The chain extender composition A comprises 60-80 parts of MOCA chain extender, 40-60 parts of hexanediol, 2-5 parts of epoxidized soybean oil, 1-1.5 parts of hydrolysis resistant agent, 0.5-1 part of antioxidant, 0.5-2 parts of catalyst, and 0.5-2.5 parts of foam stabilizer.

[0009] The chain extender composition B comprises 100-120 parts of MOCA chain extender, 10-15 parts of modified calcium carbonate whiskers, 1-1.5 parts of hydrolysis resistant agent, 0.5-1 part of antioxidant, 0.5-2 parts of catalyst, and 0.5-2.5 parts of foam stabilizer.

[0010] As a further optimization of the present invention, the ratio of the polyurethane prepolymer to chain extender composition A and chain extender composition B is 100:10-40.

[0011] As a further optimization of the present invention, the NCO content of the polyurethane prepolymer is 6-12%.

[0012] As a further optimization of the present invention, the method for preparing the modified calcium carbonate whiskers is as follows: first, add the silane coupling agent to anhydrous ethanol, heat and stir until completely dissolved to obtain a silane coupling agent solution, then add the calcium carbonate whiskers to the silane coupling agent solution, disperse by ultrasonication, react by stirring in a water bath, stand and dry to obtain the modified calcium carbonate whiskers.

[0013] As a further optimization of the present invention, the catalyst is triethylenediamine or bis(2-methoxyethyl)amine, the foam stabilizer is an organosilicon surfactant, and the hydrolysis resistant agent is carbodiimide.

[0014] As a second aspect of the present invention, a method for preparing a buffer block for a pump air chamber as described in any of the above-described embodiments is also provided, comprising the following steps:

[0015] (1) React excess diphenylmethane diisocyanate with polyol at 80-85 °C to obtain polyurethane prepolymer, add the raw material for preparing chain extender composition A to polyurethane prepolymer to obtain the raw material for preparing buffer block core layer;

[0016] (2) React excess diphenylmethane diisocyanate with polyol at 80-85 °C to obtain polyurethane prepolymer, add the raw material for preparing chain extender composition B to polyurethane prepolymer to obtain the raw material for preparing buffer block core layer;

[0017] (3) The raw materials for preparing the buffer block shell and core layer are injected into the mold by coaxial casting to form an elastomer. After applying gradient pressure to the elastomer through the mold, it is demolded and cured.

[0018] As a further optimization of the present invention, in step (1), the polyol is selected from polyester polyols with a hydroxyl value of 56-140 mgKOH / g and a number-average molecular weight Mn of 2000-4000.

[0019] As a further optimization of the present invention, in step (3), the application of gradient pressure means: maintaining the elastomer in a pressure-free state for 1-5 min, applying a pressure of 50-55 N to the elastomer for 5-10 min, applying a pressure of 50-100 N to the elastomer for 10-15 min, and restoring the elastomer to a pressure-free state for 15-20 min.

[0020] As a third aspect of the invention, the application of a buffer block for an air chamber as described above in a mud pump is also provided.

[0021] As a further optimization of the present invention, the medium transported by the mud pump is corrosive mud containing acid or alkali.

[0022] In summary, the beneficial effects of the present invention are as follows:

[0023] The buffer block provided by this invention is prepared by a prepolymer method. First, diphenylmethane diisocyanate is reacted with a polyol to obtain a polyurethane prepolymer. Then, it is mixed with chain extender composition A and chain extender composition B to obtain raw materials for preparing the shell and core layers of the buffer block. The raw materials for preparing the shell and core layers of the buffer block are then coaxially cast into a mold for molding. Through the optimization of the composition of chain extender composition A and chain extender composition B, the core layer of the buffer block has excellent toughness, the shell layer of the buffer block has good strength, and it has excellent acid and alkali resistance and wear resistance. This allows the buffer block as a whole to play an effective pressure stabilizing role, adapt to complex conveying media, and has excellent dynamic fatigue performance. When applied to the air jacket structure of a mud pump, it helps to effectively stabilize the pressure of the mud pump for a long time. It is practical, reliable, more durable, and has good application prospects. Attached Figure Description

[0024] Figure 1 A schematic diagram of coaxial casting of the buffer block provided by the present invention;

[0025] Figure 2 The present invention provides buffer blocks of different shapes and buffer block assemblies applied to air bags. Detailed Implementation

[0026] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0027] I. Materials and Methods

[0028] Unless otherwise specified, all methods used in this invention are conventional methods known to those skilled in the art. Where specific conditions are not specified, they shall be performed according to conventional conditions or conditions recommended by the manufacturer. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0029] Diphenylmethane diisocyanate (MDI), purity ≥ 99.5%;

[0030] The polyol is selected from polyester polyols with a hydroxyl value of 56-140 mg KOH / g and a number-average molecular weight Mn of 2000-4000. In the experimental content of this invention, the polyhexanediol adipate polyol with a number-average molecular weight Mn of 2000 and a hydroxyl value of 56 mg KOH / g is selected.

[0031] MOCA(3,3) ， -Dichloro-4,4 ， (-Diaminodiphenylmethane) chain extender, belonging to the aromatic diamine chain extender class, with the chemical formula C2... 13 H 12 Cl2N2;

[0032] Hexanediol (HDO) is a symmetrical aliphatic diol with hydroxyl groups at both ends, with the chemical formula C6H10. 14 O2;

[0033] Epoxidized soybean oil (ESO), chemical formula C 57 H 98 O 12 Epoxy value ≥6;

[0034] Calcium carbonate whiskers are needle-like single crystals, 20-80 μm in length, 0.5-2 μm in diameter, with an aspect ratio of 20-30 and a density of approximately 2.8 g / cm³. 3 It exhibits good thermal stability below 800 ℃;

[0035] The catalyst is triethylenediamine or bis(2-methoxyethyl)amine; the foam stabilizer is an organosilicon surfactant; and the hydrolysis resistant agent is carbodiimide.

[0036] II. Test Content

[0037] 1. Preparation of polyurethane prepolymer

[0038] Polyhexane adipate polyol with a number average molecular weight (Mn) of 2000 and a hydroxyl value of 56 mg KOH / g was dehydrated at approximately 110°C for 2 h. Then, the temperature was lowered to 50°C, and an excess of molten diphenylmethane diisocyanate (MDI) was added. The mixture was stirred rapidly to allow it to heat up naturally. When the temperature remained essentially constant, the temperature was raised to 80-85°C and reacted for 2 h. After degassing for 1 h, a polyurethane prepolymer was obtained. In the experimental content of this invention, the NCO content of the polyurethane prepolymer was controlled at 8%.

[0039] 2. Preparation of buffer blocks with core-shell structure

[0040] The raw materials for preparing the core layer of the buffer block include a polyurethane prepolymer and chain extender composition A, and the raw materials for preparing the shell layer of the buffer block include a polyurethane prepolymer and chain extender composition B.

[0041] In this invention, the chain extender composition A includes 60-80 parts of MOCA chain extender, 40-60 parts of hexanediol, 2-5 parts of epoxidized soybean oil, 3-5 parts of water, 0.5-2 parts of catalyst, 0.5-2.5 parts of foam stabilizer, and 0.5-1 parts of antioxidant.

[0042] In this invention, the chain extender composition B includes 100-120 parts of MOCA chain extender, 10-15 parts of modified calcium carbonate whiskers, 1-1.5 parts of hydrolysis resistant agent, 0.5-2 parts of catalyst, 0.5-2.5 parts of foam stabilizer and 0.5-1 parts of antioxidant.

[0043] The preparation steps for a buffer block with a core-shell structure are as follows:

[0044] First, at a temperature of 60 ℃, the raw materials for preparing chain extender composition A are added to the polyurethane prepolymer and stirred and mixed evenly to obtain the raw materials for preparing the buffer core layer. At a temperature of 60 ℃, the raw materials for preparing chain extender composition B are added to the polyurethane prepolymer and stirred and mixed evenly to obtain the raw materials for preparing the buffer core layer.

[0045] Then, the raw materials for preparing the buffer block shell and core layers are coaxially cast (casting diagram shown in Figure 1). Figure 2 (As shown) It is injected into a mold at a temperature of 65 ℃ and molded to form an elastomer;

[0046] Finally, after applying gradient pressure to the elastomer using the molds, demold it and cure it at 90 ℃ for 12 hours.

[0047] Applying gradient pressure means: keeping the elastomer in a pressure-free state for 1-5 minutes, applying a pressure of 50-55 N to the elastomer for 5-10 minutes, applying a pressure of 50-100 N to the elastomer for 10-15 minutes, and allowing the elastomer to return to a pressure-free state for 15-20 minutes.

[0048] 3. Verification Experiment

[0049] 3.1 Optimization of raw material ratio for preparing the buffer block core layer

[0050] The raw materials for preparing the buffer core layer include a polyurethane prepolymer and chain extender composition A, wherein the polyurethane prepolymer used is the same as shown in Section 1. The chain extender composition A provided by this invention, by weight, comprises 60-80 parts of MOCA chain extender, 40-60 parts of hexanediol, 2-5 parts of epoxidized soybean oil, 3-5 parts of water, 0.5-2 parts of catalyst, 0.5-2.5 parts of foam stabilizer, and 0.5-1 parts of antioxidant. To obtain a buffer core layer material with excellent performance, the raw material ratio of chain extender composition A is adjusted according to Table 1.

[0051] Table 1. Raw material ratio of chain extender composition A

[0052] ;

[0053] According to the raw material ratio of chain extender composition A given in Table 1, the raw materials for preparing chain extender composition A were added to the polyurethane prepolymer at a temperature of 60 ℃, stirred and mixed evenly, poured into a mold for foaming, and when the mixture reached a milky white color, the mold was sealed and subjected to a reaction molding under a pressure of 10 MPa to obtain core layer specimens, denoted as A-1 to A-3, a-1 to a-3. The core layer specimens were demolded and cured at 90 ℃ for 12 h. Finally, after being placed at room temperature for 7 days, the following tests were performed on the core layer specimens:

[0054] (1) Refer to GB / T 531.1-2008 and use a rubber and plastic Shore A hardness tester to test the hardness of the specimen.

[0055] (2) Tensile strength and elongation at break shall be tested using a universal testing machine in accordance with ASTM D3574-17 standard. The specimen size shall be 150 mm × 25 mm × 10 mm and the tensile rate shall be 500 mm / min.

[0056] (3) The compression permanent deformation was tested in accordance with DIN ISO 815-1:2016. The specimen size requirements were: diameter 29.0 mm ± 0.5 mm, thickness 12.5 mm ± 0.5 mm. The original height H0 and shim height H2 of the specimen were measured. The height of the specimen was compressed by 40% and placed in a circulating air chamber at 80 ℃ for 22 h. The specimen was then removed, kept in a compressed state, and cooled to room temperature for 2 h. After depressurization for 10 min, the height H1 of the specimen was measured to an accuracy of 0.1 mm.

[0057] The formula for calculating compression permanent deformation is: Cs% = (H0-H1) / (H0-H2) × 100%.

[0058] The results are shown in Table 2.

[0059] Table 2. Performance Test Results

[0060] ;

[0061] As can be seen from Table 2, when the amount of MOCA chain extender increases, the hardness and tensile strength of the specimen will increase to a certain extent, but the elongation at break will decrease accordingly. MOCA reacts with NCO to produce more substituted urea groups and contains benzene rings, which can provide rigidity for the hard segment, improve the regularity of the hard segment, and improve the mechanical properties.

[0062] Under the condition that the dosage of chain extender composition A and the dosage of the other components of chain extender composition A are the same, the combined use of MOCA chain extender and hexanediol has a positive effect on obtaining core layer materials with both strength and toughness compared to using MOCA chain extender or hexanediol alone. This is because hexanediol is a linear small molecule with a symmetrical structure, and the hard segments generated have a certain degree of flexibility, which is conducive to the interlacing and aggregation of soft and hard segments, reduces the degree of phase separation, and improves the elongation at break of the material.

[0063] Finally, comparing specimens A-3 and a-3, the addition of epoxidized soybean oil to the binary chain extender system of MOCA chain extender and hexanediol has a positive effect on promoting the elongation at break while ensuring the hardness and tensile strength of the core material, thus making the core material both strong and tough.

[0064] 3.2 Optimization of raw material ratio for preparing the buffer block shell layer

[0065] The raw materials for preparing the buffer block core layer include a polyurethane prepolymer and a chain extender composition A, wherein the polyurethane prepolymer used is the same as shown in Section 1. The chain extender composition B provided by the present invention includes 100-120 parts of MOCA chain extender, 10-15 parts of modified calcium carbonate whiskers, 1-1.5 parts of hydrolysis resistant agent, 0.5-2 parts of catalyst, 0.5-2.5 parts of foam stabilizer, and 0.5-1 parts of antioxidant.

[0066] To obtain a high-performance buffer block core layer material, the raw material ratio of chain extender composition B was adjusted according to Table 3.

[0067] Table 3. Raw material ratio of chain extender composition B

[0068] ;

[0069] According to the raw material ratio of chain extender composition B given in Table 3, the raw materials for preparing chain extender composition B were added to the polyurethane prepolymer at a temperature of 60 ℃, stirred and mixed evenly, poured into a mold for foaming, and when the milky white color was reached, the mold was sealed and placed under a pressure of 10 MPa to react and form shell specimens, which were designated as B-1 to B-3 and b-1 to b-4. The core specimens were demolded and placed at 90 ℃ for 12 h for curing. Finally, they were placed at room temperature for 7 days.

[0070] The shell material was tested using the same test items as the core material, and the results are shown in Table 4.

[0071] Table 4. Performance Test Results

[0072] ;

[0073] Table 4 shows that the amount of MOCA chain extender is positively correlated with the improvement of the hardness and tensile strength of the shell material. A comparison of the data from specimens B-3 and B-4 reveals that the combined use of modified calcium carbonate whiskers and MOCA chain extender promotes a simultaneous increase in the strength and toughness of the shell material. Unmodified calcium carbonate whiskers are not conducive to their dispersion in polyurethane prepolymers. Modification with surfactants improves their dispersion performance, which helps them to exert a synergistic effect with MOCA chain extender. Furthermore, compared to the use of nanomaterials—nano-calcium carbonate—modified calcium carbonate whiskers are more effective in strengthening the shell material structure.

[0074] Furthermore, since the shell material, as the outer layer material of the buffer block, is in direct contact with the medium, the shell material's good adaptability to the medium is of positive significance for expanding the application scenarios of the buffer block. Therefore, the acid and alkali resistance and wear resistance of the shell material are tested.

[0075] The specific test items are as follows:

[0076] (1) For acid and alkali resistance, refer to GB / T 13353-92 standard. Use sulfuric acid solution and sodium hydroxide solution with a mass concentration of 10% each. Immerse the shell specimens in the sulfuric acid solution and sodium hydroxide solution respectively. After 10 days, take them out and measure the mass change rate of each shell specimen. The smaller the mass change rate, the stronger the acid and alkali resistance. The mass before immersion is recorded as M0, and the mass after immersion is recorded as M1. Mass change rate (%) = {(M0-H1) / M0}×100%.

[0077] (2) Regarding wear resistance, refer to GB / T 1689-2014 standard. The shell material is fixed on the Akron abrasion tester and rubbed against the grinding wheel at a specified tilt angle (usually 15°±0.5°) and load (26.7 N±0.2 N). After a specified mileage (1.61 km), the mass loss of the sample is measured and the wear volume is calculated. The grinding wheel shaft speed is 34 r / min±1 r / min. The shell material size requirement is an outer diameter of about 68 mm and a thickness of 12.7 mm±0.2 mm. The smaller the Akron abrasion, the stronger the wear resistance.

[0078] The results are shown in Table 5.

[0079] Table 5. Performance Test Results

[0080] ;

[0081] As shown in Table 5, the shell material has good acid and alkali resistance and wear resistance. As the outer layer structure of the buffer block, it helps to improve the acid and alkali resistance and wear resistance of the buffer block, and can effectively adapt to complex conveying media of acid or alkali. When applied to the air jacket of the mud pump, it can adapt to different mud pump conveying media and is durable. The addition of modified calcium carbonate whiskers has a positive effect on improving the acid and alkali resistance and wear resistance of the shell material, and the improvement effect is better than that of modified calcium sulfate whiskers. Unmodified calcium carbonate whiskers affect its dispersibility in the shell material, which is not conducive to the performance of acid and alkali resistance and wear resistance.

[0082] 3.3 Optimization of the structure and preparation method of the buffer block

[0083] Considering the properties of both the core and shell materials, the raw materials for preparing core material A-3 and shell material B-2 were selected, and a coaxial casting method was adopted (see schematic diagram of coaxial casting as shown). Figure 1 (As shown) The elastomer is molded in a mold at a temperature of 65 ℃ to form an elastomer. After applying gradient pressure to the elastomer through the mold, it is demolded and cured at 90 ℃ for 12 h.

[0084] Adjust the pressure application method according to the following groups:

[0085] Pressure application method C-1: Keep the elastomer in a pressure-free state for 1-5 minutes, apply a pressure of 50 N to the elastomer for 5-10 minutes, apply a pressure of 100 N to the elastomer for 10-15 minutes, and return the elastomer to a pressure-free state for 15-20 minutes.

[0086] Pressure application method C-2: Keep the elastomer in a pressure-free state for 1-5 minutes, apply 100 N pressure to the elastomer for 5-10 minutes, apply 50 N pressure to the elastomer for 10-15 minutes, and return the elastomer to a pressure-free state for 15-20 minutes.

[0087] Pressure application method C-3: Keep the elastomer in a pressure-free state for 1-5 minutes, apply a pressure of 50 N to the elastomer for 5-15 minutes, and restore the elastomer to a pressure-free state for 15-20 minutes.

[0088] Pressure application method C-4: Keep the elastomer in a pressure-free state for 1-5 minutes, apply 100 N of pressure to the elastomer for 5-15 minutes, and restore the elastomer to a pressure-free state for 15-20 minutes.

[0089] Pressure application method C-5: Apply 100 N of pressure to the elastomer within 1-20 min.

[0090] Different buffer block specimens were prepared according to different pressure application methods and were designated as C-1 to C-5. In addition, a buffer block specimen prepared by keeping the elastomer in a pressure-free state for 1-20 min was used as a control group specimen and was designated as C-6.

[0091] In addition, to investigate the performance of the core-shell structured buffer block, a core-shell-free buffer block prepared from the raw materials for preparing the shell material and a core-shell-free buffer block prepared from the raw materials for preparing the core material were designated as C-7 and C-8, respectively.

[0092] A core-layer buffer block is prepared using raw materials for preparing core-layer materials. Then, a shell-layer buffer block is prepared using raw materials for preparing shell-layer materials to wrap the core-layer buffer block around its outer periphery, resulting in a buffer block with a core-shell structure. Finally, pressure is applied according to pressure application method C-1. The resulting buffer block is denoted as C-9.

[0093] Dynamic fatigue tests were conducted on buffer block specimens C-1 to C-9. The dynamic fatigue resistance of the specimens was characterized by the number of compression cycles required before the specimens began to fracture under cyclic compression. The more compression cycles the specimens underwent before fracture began, the better their durability under pressure and heat, and the better their dynamic fatigue resistance; conversely, fewer compression cycles indicate poorer dynamic fatigue resistance. The specific operating method is as follows:

[0094] A specimen measuring 50 mm × 50 mm × 25 mm was mounted on the support fixture of the dynamic testing machine. The pressure was set to 0-6 kN and the compression frequency to 2.0 Hz. Without air cooling, the number of compressions performed on the specimen before it began to fracture was recorded. This was repeated 5 times, and the average value was calculated to obtain the average number of compressions at which the specimen began to fracture.

[0095] The results are shown in Table 6.

[0096] Table 6. Performance Test Results

[0097] ;

[0098] As can be seen from Table 6, by first injecting the raw materials for preparing the shell material and the raw materials for preparing the core material into the mold in a coaxial casting manner to form an elastomer, and then sealing the mold, the elastomer is subjected to gradient pressure in pressure application method C-1 between the molds. The resulting buffer block has good dynamic fatigue resistance. Moreover, under the premise of a certain pressure application method, the method of injecting the raw materials for preparing the shell material and the raw materials for preparing the core material into the mold in a coaxial casting manner can optimize the interface morphology between the core and shell layers, so that the buffer block has good dynamic fatigue resistance. When applied to the air jacket structure of the mud pump, it helps to effectively stabilize the pressure of the mud pump for a long time.

[0099] Application of buffer blocks in mud pumps

[0100] The specific application of the buffer block provided by this invention in a mud pump is as follows: First, the buffer blocks are assembled into a buffer block assembly. The shape of the buffer block prepared by molding can be cylindrical, 1 / 2 cylindrical, or 1 / 4 cylindrical, as shown in the figure below. Figure 2 The diagram shows how individual buffer blocks are combined into a buffer block assembly. The diagrams show a buffer block assembly composed of three cylindrical buffer blocks and a buffer block assembly composed of 12 quarter-cylinder buffer blocks. Damping holes can be further opened on the buffer blocks according to the buffering requirements.

[0101] Subsequently, the buffer block assembly is inserted into the capsule body, the shape of which is adapted to the shape of the buffer block assembly;

[0102] The air chamber has a cavity-shaped shell with connection ports at the top and bottom. The internal cavity is ellipsoidal, and the external shape is approximately spherical. The bottom is connected to the mud pump outlet branch via a connecting flange. The capsule body containing the buffer block assembly extends into the air chamber shell, with its upper end locked into the upper plane groove of the shell. The capsule body preferably has damping holes for buffering around its perimeter and bottom. The top connecting flange of the air chamber is bolted to the upper part of the shell, and the protruding part of the top connecting flange extends into the capsule body to fix the capsule body in place.

[0103] The unbalanced pressure generated during the operation of the mud pump is balanced and stabilized by the energy storage and release of the bladder and buffer block inside the air chamber. Through the design of the buffer block structure, raw materials and processes for preparing the buffer block, a buffer block with excellent plasticity, acid and alkali resistance and wear resistance is applied to the air chamber of the mud pump, which can effectively stabilize the pressure and adapt to complex conveying media. At the same time, the buffer block provided by this invention has excellent dynamic fatigue performance. Its application in the air chamber structure of the mud pump helps to effectively stabilize the pressure of the mud pump for a long time. It is practical, reliable and more durable, and has good application prospects.

[0104] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various improvements without departing from the concept of the present invention, and these improvements all fall within the scope of protection of the present invention.

Claims

1. A buffer block for an air jacket in a pump, characterized in that, The buffer block has a core-shell structure. The raw materials for preparing the core layer of the buffer block include a polyurethane prepolymer and chain extender composition A, and the raw materials for preparing the shell layer of the buffer block include a polyurethane prepolymer and chain extender composition B. The ratio of polyurethane prepolymer to chain extender composition A for preparing the core layer of the buffer block and the ratio of polyurethane prepolymer to chain extender composition B for preparing the shell layer of the buffer block are both 100:10-40. The NCO content of the polyurethane prepolymer is 6-12%; The chain extender composition A, by weight, comprises 60-80 parts of MOCA chain extender, 40-60 parts of hexanediol, 2-5 parts of epoxidized soybean oil, 3-5 parts of water, 0.5-1 parts of antioxidant, 0.5-2 parts of catalyst, and 0.5-2.5 parts of foam stabilizer. The chain extender composition B, by weight, comprises 100-120 parts of MOCA chain extender, 10-15 parts of modified calcium carbonate whiskers, 1-1.5 parts of hydrolysis resistant agent, 0.5-1 part of antioxidant, 0.5-2 parts of catalyst, and 0.5-2.5 parts of foam stabilizer. The modified calcium carbonate whiskers are prepared by: first adding silane coupling agent to anhydrous ethanol, heating and stirring until completely dissolved to obtain silane coupling agent solution, then adding calcium carbonate whiskers to silane coupling agent solution, dispersing by ultrasound, reacting by stirring in a water bath, standing and drying to obtain modified calcium carbonate whiskers. The method for preparing the buffer block for the air chamber of the pump includes the following steps: (1) React excess diphenylmethane diisocyanate with polyol at 80-85 °C to obtain polyurethane prepolymer, add the raw material for preparing chain extender composition A to polyurethane prepolymer to obtain the raw material for preparing buffer block core layer; (2) React excess diphenylmethane diisocyanate with polyol at 80-85 °C to obtain polyurethane prepolymer. Add the raw material for preparing chain extender composition B to polyurethane prepolymer to obtain the raw material for preparing buffer block shell layer. (3) The raw materials for preparing the buffer block shell and core layer are injected into the mold by coaxial casting to form an elastomer. After applying gradient pressure to the elastomer through the mold, it is demolded and cured. The polyol is selected from polyester polyols with a hydroxyl value of 56-140 mg KOH / g and a number-average molecular weight Mn of 2000-4000. The application of gradient pressure refers to: maintaining the elastomer in a pressure-free state for 1-5 minutes, applying a pressure of 50-55 N to the elastomer for 5-10 minutes, applying a pressure of 50-100 N to the elastomer for 10-15 minutes, and restoring the elastomer to a pressure-free state for 15-20 minutes.

2. A buffer block for an air jacket in a pump according to claim 1, characterized in that, The catalyst is triethylenediamine or bis(2-methoxyethyl)amine, the foam stabilizer is an organosilicon surfactant, and the hydrolysis resistant agent is carbodiimide.

3. The application of a buffer block for an air chamber as described in any one of claims 1-2 in a mud pump.

4. The application according to claim 3, characterized in that, The medium transported by the mud pump is corrosive mud containing acid or alkali.

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