Vacuum infiltration preparation method and application of integrated copper-steel composite bimetallic rotor

Abstract

The invention belongs to the technical field of bimetallic material preparation, and relates to a vacuum infiltration preparation method and application of an integrated copper-steel composite bimetallic rotor. The method comprises the following steps that firstly, a steel billet is subjected to normalizing treatment and then is machined into a rotor cylinder body blank, an outer cylinder sleeve and a copper alloy core rod are machined according to the size of the rotor cylinder body blank, and cleaning treatment is conducted; assembling the cleaned rotor cylinder body blank into an outer cylinder sleeve, and assembling the cleaned copper alloy core rod into a plunger hole to form a blank assembly; then the blank assembly is put into a vacuum furnace for heating and heat preservation, annealing treatment is conducted after cooling and discharging, and a rotor blank is formed; and finally, the rotor blank is machined to the specified size, and the copper-steel composite bimetal rotor is formed. The prepared copper-steel bimetallic composite bimetallic rotor has the remarkable advantages of being high in bonding strength, excellent in process reliability, short in production period, high in product batch stability and the like.

Description

Technical Field

[0001] This invention belongs to the field of bimetallic material preparation technology, and relates to the vacuum melting infiltration preparation method and application of an integrated copper-steel composite bimetallic rotor. Background Technology

[0002] The power systems of heavy-duty engineering vehicles, armored vehicles, and large hydraulic equipment, as well as the attitude control systems and actuation systems of aircraft, all rely on high-pressure or ultra-high-pressure hydraulic systems to achieve their core functions. As a key component of the hydraulic system, the piston pump is the core component for pressure output, while the hydraulic motor is the core component for power conversion. The rotor, as the core rotating element of both the piston pump and the hydraulic motor, must withstand harsh operating conditions during operation: the end face must withstand high-speed, high-pressure circumferential friction, and the cavity must withstand high-speed, high-pressure reciprocating friction. Therefore, in the rotor design, the base material is made of steel to ensure structural strength, while the end face and inner cavity are made of wear-resistant copper alloy (specifically bronze alloy) to meet the durability requirements under high-pressure friction scenarios.

[0003] Currently, the copper alloy at the contact face between the rotor and the distribution plate (i.e., the distribution pair) is composited onto the steel substrate surface using an inlay casting process; while the copper alloy at the side wall of the rotor plunger bore cavity (plunger pair) is produced by mechanically pressing a pre-machined copper sleeve into the cylinder body using an interference fit. The plunger bore cavity manufactured using this mechanical pressing method is generally stable and reliable under medium- and low-pressure hydraulic system conditions below 30 MPa; however, when the hydraulic system pressure exceeds 30 MPa, gaps may form between the copper alloy sleeve on the plunger bore cavity side wall and the steel cavity, leading to oil leakage, relative loosening, or even detachment. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and to propose a vacuum melting infiltration preparation method and application of an integrated copper-steel composite bimetallic rotor.

[0005] On the one hand, this invention provides a vacuum infiltration method for preparing an integrated copper-steel composite bimetallic rotor, such as... Figure 1 As shown, it includes the following steps: Step 1: After normalizing the steel billet, it is machined into a rotor cylinder blank. The outer cylinder liner is machined according to the dimensions of the rotor cylinder blank. The copper alloy core rod is prepared according to the plunger hole dimensions in the rotor cylinder blank. The rotor cylinder blank, copper alloy core rod and outer cylinder liner are then cleaned. Specifically, the steel billet is cut from steel bars (materials such as 45 steel and 42CrMo can be selected) according to specific specifications; the rotor cylinder blank is processed according to specifications using turning, drilling, milling, boring and other processes. The rotor cylinder blank includes one central plunger through hole and nine peripheral plunger blind holes. Step 2: First, assemble the cleaned rotor cylinder blank into the outer cylinder liner, and then assemble the cleaned copper alloy mandrel into the plunger hole to form the blank assembly. Specifically, the second step is to place the rotor cylinder blank with the hole facing upward into the outer cylinder liner, then insert the copper alloy mandrel into the corresponding central plunger through hole and the surrounding plunger blind hole respectively, and finally cover it with an alumina refractory ceramic cover. Step 3: First, put the billet assembly into a vacuum furnace for heating and heat preservation. After the heat preservation is completed, cool it out of the furnace and then perform annealing to form a rotor blank. Step 4: Machin the rotor blank to the specified dimensions to form a copper-steel composite bimetallic rotor.

[0006] Furthermore, in step one, the heating temperature of the normalizing treatment is 700℃~1000℃, the holding time is 1h~5h, and the furnace is then air-cooled.

[0007] Specifically, normalizing treatment can reduce the hardness of steel billets, improve machinability, eliminate internal stress in steel billets, improve processing quality and efficiency, and optimize the performance of the final product.

[0008] Furthermore, in step one, the inner diameter of the outer cylinder liner is 0.1mm to 1mm larger than the outer diameter of the rotor cylinder blank, and the inner height of the outer cylinder liner is 2mm to 10mm larger than the height of the rotor cylinder blank.

[0009] Specifically, the inner diameter of the outer cylinder liner is 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or 1mm larger than the outer diameter of the rotor cylinder blank; the inner height of the outer cylinder liner is 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm larger than the height of the rotor cylinder blank, depending on the actual requirements.

[0010] Furthermore, in step one, the diameter of the copper alloy core rod is 0.5mm to 1mm smaller than the diameter of the corresponding plunger hole, and the height of the copper alloy core rod is 0.5mm to 5mm larger than the height of the corresponding plunger hole.

[0011] Specifically, the copper alloy mandrel includes one pre-formed copper alloy mandrel with a central hole and nine pre-formed copper alloy mandrels with nine support plug holes. The diameter of the pre-formed copper alloy mandrel with a central hole is 0.5mm to 1mm smaller than the diameter of the central plunger through hole in the cylinder block, and its height is 0.5mm to 5mm larger than the height of the central plunger through hole. The diameter of the pre-formed copper alloy mandrel with nine support plug holes is 0.5mm to 1mm smaller than the diameter of the blind holes of the four plungers, and its height is 0.5mm to 5mm larger than the height of the blind holes of the four plungers. The reserved diameter and height of the copper alloy mandrel are mainly to improve the assemblability of the billet assembly and the filling rate of the molten copper alloy.

[0012] Furthermore, in step one, the cleaning process involves first cleaning the rotor cylinder blank, copper alloy core rod, and outer cylinder liner with a sodium hydroxide solution to remove oil, then rinsing with water until neutral, and finally drying.

[0013] Specifically, the cleaning process involves first using a 3%–10% sodium hydroxide aqueous solution or other detergent to degrease the processed rotor cylinder blank, copper alloy core rod, outer cylinder liner, etc., then rinsing with clean water until neutral, and finally drying the moisture in an oven at 50℃–100℃. Furthermore, in step three, the vacuum level inside the vacuum furnace is ≤5Pa.

[0014] Furthermore, in step three, the billet assembly is heated to a temperature of 900℃~1200℃ in a vacuum furnace, and the holding time is 2h~6h.

[0015] Specifically, the actual heating temperature needs to be determined based on the melting point of the selected copper alloy. Generally, it is selected within the range of 50℃ to 250℃ above the melting point of the copper alloy. The holding time is determined based on the thickness of the blank. Within this temperature range, the interfacial energy between the bimetals can be increased. By holding for an appropriate time, the molten metal can penetrate into the base alloy to form a chemical bond, giving the bimetallic bonding surface a high bonding strength.

[0016] Furthermore, in step three, the annealing temperature is 500℃~700℃, and the holding time is 2h~6h. The selection of the annealing temperature is based on the recrystallization temperature and interfacial reaction temperature of the two components, and the selection of the holding time is based on the workpiece size and interfacial diffusion kinetics. Annealing temperature and holding time within this range can effectively eliminate and homogenize internal stress, optimize material properties, stabilize microstructure, and improve interfacial bonding performance, thus providing a guarantee for subsequent processing and use.

[0017] On the other hand, this invention discloses the application of a copper-steel bimetallic rotor prepared by the vacuum melting and infiltration method described above in a high-pressure plunger pump or hydraulic motor.

[0018] Compared with the prior art, the present invention has the following beneficial effects: Compared with traditional mechanical pressing and casting methods, the copper-steel bimetallic composite bimetallic rotor prepared by this invention has significant advantages such as high bonding strength, excellent process reliability, short production cycle, and strong batch stability. Compared with mechanical pressing, it can effectively solve the problems of gap leakage, loosening and falling off of the copper layer of the plunger friction pair under high pressure load. Compared with casting, it can significantly eliminate the porosity defects inside the copper alloy and further improve the bonding strength of the copper-steel interface. The core process principle of this invention is to achieve integrated composite by utilizing the difference in melting points of dissimilar metals: First, a high-melting-point metal (steel) is processed into a rotor cylinder blank with plunger holes; then, a pre-made low-melting-point metal—copper alloy (specifically bronze alloy) mandrel is inserted into the plunger holes of the rotor cylinder blank; after loading into the furnace, the bimetallic material is heated until the low-melting-point metal is in a molten state to increase the interfacial energy between the bimetallic materials. The material is then held at a high temperature for a specific time to promote the molten copper alloy to fully penetrate into the surface of the solid steel, forming a chemical bond and giving the bimetallic bonding surface a high bonding strength. Finally, the copper alloy is cooled to solidify sequentially, ensuring the uniformity of composition, reducing alloy defects, and ultimately forming a copper alloy-steel integrated bimetallic rotor blank. Attached Figure Description

[0019] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of the method steps of the present invention; Figure 2 This is a cross-sectional view of the rotor cylinder blank of Example 1; Figure 3 This is a top view of the rotor cylinder blank of Example 1; Figure 4 This is a schematic diagram of the blank assembly in Example 1; Figure 5 This is a schematic diagram of the melt infiltration and solidification effect in Example 1. Figure 6 This is a schematic diagram of the finished product processing in Example 1; Figure 7 This is a high-magnification image of the bonding surface of the bimetallic rotor after melting and infiltration in Example 1; Figure 8 This is a cross-sectional view of the rotor cylinder blank in Example 2; Figure 9 This is a schematic diagram of the blank assembly in Example 2; Figure 10 This is a schematic diagram of the melt infiltration and solidification effect in Example 2; Figure 11 This is a cross-sectional view of the finished product from Example 2; Figure 12 This is a top view of the finished product processing in Example 2; Figure 13 This is a high-magnification image of the bonding surface of the bimetallic rotor after melting and infiltration in Example 2.

[0022] Wherein: 1 is an alumina refractory ceramic cover; 2 is a copper alloy core rod; 3 is a rotor cylinder blank; 4 is an outer cylinder liner. Detailed Implementation

[0023] Exemplary embodiments will now be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0024] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] This invention provides a vacuum infiltration method for preparing an integrated copper-steel composite bimetallic rotor, specifically including the following steps: Step 1, Steel bar cutting: Cut steel bars (materials such as 45 steel and 42CrMo) according to the specifications of the processed billet to form steel billets; Step 2, billet normalizing: Determine the heating temperature according to the specifications, 700℃~1000℃, hold for 1h~5h, and air cool after removal from the furnace; Step 3: According to the drawing requirements, use turning, drilling, milling, boring and other processes to process the rotor cylinder blank 3. The rotor cylinder blank 3 includes 1 central plunger through hole and 9 peripheral plunger blind holes. Step 4: Machining the outer cylinder liner 4: Based on the dimensions of the rotor cylinder blank 3, machine a 45 steel outer cylinder liner 4. The inner diameter of the outer cylinder liner 4 is 0.1mm to 1mm larger than the outer diameter of the rotor cylinder blank 3, and the inner height of the outer cylinder liner 4 is 2mm to 10mm larger than the height of the rotor cylinder blank 3. Step 5: Machining copper alloy mandrel 2: 1 pre-made copper alloy mandrel with a center hole diameter 0.5mm to 1mm smaller than the cylinder block center hole diameter and a height 0.5mm to 5mm higher than the cylinder block center hole height; 9 pre-made copper alloy mandrels with support plug holes, a diameter 0.5mm to 1mm smaller than the cylinder block plunger hole diameter and a height 0.5mm to 5mm higher than the cylinder block plunger hole height. Step 6, Cleaning and degreasing: Use a 3% to 10% sodium hydroxide aqueous solution or other detergent to clean and degrease the processed rotor cylinder blank 3, copper alloy core rod 2, outer cylinder liner 4, etc., and then rinse with clean water until neutral, and then dry the moisture in an oven at 50℃ to 100℃. Step 7, Assembly: Place the rotor cylinder blank 3 with the opening facing up into the outer cylinder liner 4, then insert 10 copper alloy mandrels into one central plunger through hole and nine peripheral plunger blind holes in sequence, and finally cover it with an alumina refractory ceramic cover 1. Step 8, Furnace loading and heating for melting and infiltration: Place the assembled components into a vacuum furnace, close the furnace door, evacuate and heat for melting and infiltration. Before heating, the vacuum degree inside the furnace should be ≤5Pa. The heating temperature should be 900℃~1200℃, and the holding time should be 2h~6h. The specific heating temperature is determined based on the melting point of the copper alloy, and is generally selected within the range of 50℃~250℃ above the melting point of the copper alloy. The holding time is determined based on the thickness of the blank. Step 9, Cooling and unloading: After the holding time reaches the specified time, argon gas is used for cooling before unloading. Step 10, Annealing: Heat the billet assembly to 500℃~700℃, hold for 2h~6h, and air cool; Step 11, Finished Product Processing: Process the rotor blank after copper alloy impregnation to the specified dimensions according to the drawings. Example 1

[0026] This embodiment provides a method for preparing a bimetallic rotor of ZCuPb10Sn10 copper alloy + 42CrMo steel: Step 1: After normalizing the steel billet, it is machined into a rotor cylinder blank 3. The outer cylinder liner 4 is machined according to the size of the rotor cylinder blank 3. The copper alloy core rod 2 is prepared according to the size of the plunger hole in the rotor cylinder blank 3. The rotor cylinder blank 3, the copper alloy core rod 2 and the outer cylinder liner 4 are cleaned. Specifically as follows: First, the steel bars are cut to size according to the specifications (φ185mm×165mm) of the billet (material: 42CrMo steel); then the billet is normalized at 900℃ for 3 hours, followed by air cooling; subsequently, the rotor cylinder blank 3 is machined as required, including one central plunger through hole and nine peripheral plunger blind holes (such as...). Figures 2-3As shown), based on the dimensions of the rotor cylinder blank 3, a 45 steel outer cylinder liner 4 is machined. The inner diameter of the outer cylinder liner 4 is φ186mm, which is 1mm larger than the outer diameter of the rotor cylinder blank 3. The inner height of the outer cylinder liner 4 is 170mm, which is 5mm larger than the height of the rotor cylinder blank 3. Then, a copper alloy mandrel 2 made of ZCuPb10Sn10 material is machined, including one pre-made copper alloy mandrel with a center hole and nine pre-made copper alloy mandrels with nine support plug holes. The specifications of the pre-made copper alloy mandrel with the center hole are φ46mm×168mm, which is larger than the corresponding... The plunger hole diameter is 0.5mm smaller and 1mm higher than the corresponding plunger hole height. The specifications of the prefabricated copper alloy core rod for the plunger hole are φ30mm×105mm, which is 0.5mm smaller and 1mm higher than the corresponding plunger hole diameter. Finally, the rotor cylinder blank 3, copper alloy core rod 2, and outer cylinder liner 4 are cleaned and degreased with a 3% sodium hydroxide aqueous solution. Then, they are rinsed with clean water until neutral and dried in a welding box at 60℃ for 1 hour. Step 2: First, assemble the cleaned rotor cylinder blank 3 into the outer cylinder liner 4, and then assemble the cleaned copper alloy core rod 2 into the plunger hole to form a blank assembly. Specifically, the rotor cylinder blank with the bore 3 facing upwards is placed into the outer cylinder liner 4. Then, 10 ZCuPb10Sn10 copper alloy mandrels are inserted sequentially into one center hole and nine plunger holes. Finally, an alumina refractory ceramic cap 1 is placed on top. (See...) Figure 4 As shown; Step 3: First, put the billet assembly into a vacuum furnace for heating and heat preservation. After the heat preservation is completed, cool it out of the furnace and then perform annealing to form a rotor blank. Specifically, the assembled components are placed in a vacuum furnace, the furnace door is closed, and a vacuum is created for heating and infiltration. Before heating, the vacuum level inside the furnace is ≤5 Pa. The heating temperature is 950℃, and the temperature is maintained for 5 hours. After cooling with argon gas, the components are removed from the furnace. The effect after infiltration and solidification is as follows: Figure 5 As shown; the billet assembly after heating and heat preservation is then annealed: the billet assembly is heated to 500℃, held for 4 hours, and then air-cooled. Step 4: Machining the rotor blank to the specified dimensions to form a copper-steel composite bimetallic rotor; Specifically, the rotor blank, after being impregnated with copper alloy, is machined to the specified dimensions. A schematic diagram of the finished product machining process is shown below. Figure 6 As shown, the bonding surface after melt infiltration is as follows Figure 7 As shown, the copper alloy is melted and diffused into the steel matrix at high temperature to form a chemical bond, allowing the liquid copper to wet and spread on the steel surface, and selectively dendritic penetrate into the interior of the steel matrix by using the grain boundaries as a rapid diffusion channel. Example 2

[0027] This embodiment provides a method for preparing a bimetallic rotor made of ZCuSn10P1 copper alloy and 45 steel: Step 1: After normalizing the steel billet, it is machined into a rotor cylinder blank 3. The outer cylinder liner 4 is machined according to the size of the rotor cylinder blank 3. The copper alloy core rod 2 is prepared according to the size of the plunger hole in the rotor cylinder blank 3. The rotor cylinder blank 3, the copper alloy core rod 2 and the outer cylinder liner 4 are cleaned. Specifically as follows: First, the steel bars are cut to size according to the specifications (φ160mm×140mm) of the billet (material is 45 steel); then the billet is normalized, heated to 800℃, held for 2.5 hours, and then air-cooled; subsequently, the rotor cylinder blank 3 is machined according to the drawings, including one central plunger through hole and nine peripheral plunger blind holes (such as... Figure 8 As shown), based on the dimensions of the rotor cylinder blank 3, an outer cylinder liner 4 made of 45 steel is machined. The inner diameter of the outer cylinder liner 4 is φ161mm, which is 0.75mm larger than the outer diameter of the rotor cylinder blank 3; the inner height of the outer cylinder liner 4 is 145mm, which is 2mm larger than the height of the rotor cylinder blank 3; then, a copper alloy mandrel 2 made of ZCuSn10P1 material is machined, including one pre-made copper alloy mandrel with a center hole and nine pre-made copper alloy mandrels with nine support plug holes. The specifications of the pre-made copper alloy mandrel with the center hole are φ35mm×148mm, which is larger than the corresponding The diameter of the plunger hole is 0.75 mm smaller than the corresponding plunger hole height, and 3 mm higher than the corresponding plunger hole height. The specifications of the prefabricated copper alloy core rod for the plunger hole are φ28 mm × 105 mm, which is 1 mm smaller than the corresponding plunger hole diameter and 0.5 mm higher than the corresponding plunger hole height. Finally, cleaning and degreasing are carried out. First, a 3% sodium hydroxide aqueous solution is used to degrease and clean the processed rotor cylinder blank 3, copper alloy core rod 2, outer cylinder liner 4, etc. Then, they are rinsed with clean water until neutral, and the moisture is dried by keeping it at 60℃ in the welding box for 1 hour. Step 2: First, assemble the cleaned rotor cylinder blank 3 into the outer cylinder liner 4, and then assemble the cleaned copper alloy mandrel 2 into the plunger hole to form a blank assembly. Specifically, the rotor cylinder blank 3 is placed into the outer cylinder liner 4 with the orifice facing upwards. Then, 10 ZCuSn10P1 copper alloy mandrels are inserted sequentially into one central plunger through hole and nine peripheral plunger blind holes. Finally, an alumina refractory ceramic cover 1 is placed on top. Figure 9 As shown; Step 3: First, put the billet assembly into a vacuum furnace for heating and heat preservation. After the heat preservation is completed, cool it out of the furnace and then perform annealing to form a rotor blank. Specifically, the assembled components are placed in a vacuum furnace, the furnace door is closed, and the furnace is evacuated and heated for melting and infiltration. Before heating, the vacuum level inside the furnace is ≤5 Pa. The heating temperature is 1000℃, and the temperature is maintained for 4 hours. After cooling with argon gas, the components are removed from the furnace. The effect after melting and solidification is as follows: Figure 10 As shown; the billet assembly after heating and heat preservation is then annealed: the billet assembly is heated to 600℃, held for 3 hours, and then air-cooled; Step 4: Machining the rotor blank to the specified dimensions to form a copper-steel composite bimetallic rotor; The rotor blank, after being impregnated with copper alloy, is machined to the specified dimensions, such as... Figures 11-12 As shown; the bonding surface of the ZCuSn10P1 copper alloy + 45 steel bimetallic rotor after melting and infiltration is as follows. Figure 13 As shown, the copper alloy is melted and diffused into the steel matrix at high temperature to form a chemical bond, allowing the liquid copper to wet and spread on the steel surface, and selectively dendritic penetrate into the interior of the steel matrix by using the grain boundaries as a rapid diffusion channel. Example 3

[0028] This embodiment provides a method for preparing a ZCuSn10P1 copper alloy + 42CrMo steel bimetallic rotor: Step 1: After normalizing the steel billet, it is machined into a rotor cylinder blank 3. The outer cylinder liner 4 is machined according to the size of the rotor cylinder blank 3. The copper alloy core rod 2 is prepared according to the size of the plunger hole in the rotor cylinder blank 3. The rotor cylinder blank 3, the copper alloy core rod 2 and the outer cylinder liner 4 are cleaned. Specifically as follows: First, the steel bars are cut to size according to the specifications (φ180×150mm) of the billet (material: 42CrMo steel). Then, the billets are normalized at 1000℃ for 1 hour, followed by air cooling. Next, the rotor cylinder blank 3 is machined according to the drawings, including one central plunger through-hole and nine peripheral plunger blind holes. Based on the dimensions of the rotor cylinder blank 3, an outer cylinder sleeve 4 made of 45 steel is machined. The inner diameter of the outer cylinder sleeve 4 is 180.1mm, 0.1mm larger than the outer diameter of the rotor cylinder blank 3; the inner height of the outer cylinder sleeve 4 is 160mm, 10mm larger than the height of the rotor cylinder blank 3. Finally, a copper alloy core rod 2 made of ZCuSn10P1 material is machined. It includes one pre-fabricated copper alloy core rod with a center hole and nine pre-fabricated copper alloy core rods with plug holes. The pre-fabricated copper alloy core rod with the center hole has a specification of φ40mm×155mm, which is 1mm smaller than the corresponding plug hole diameter and 5mm higher than the corresponding plug hole height. The pre-fabricated copper alloy core rod with the plug holes has a specification of φ30mm×120mm, which is 0.75mm smaller than the corresponding plug hole diameter and 5mm higher than the corresponding plug hole height. Finally, it is cleaned and degreased. First, a 3% sodium hydroxide aqueous solution is used to degrease and clean the processed rotor cylinder blank 3, copper alloy core rod 2, outer cylinder liner 4, etc., and then rinsed with clean water until neutral. The moisture is dried by keeping it at 60℃ in the welding box for 1 hour. Step 2: First, assemble the cleaned rotor cylinder blank 3 into the outer cylinder liner 4, and then assemble the cleaned copper alloy mandrel 2 into the plunger hole to form a blank assembly. Specifically, the rotor cylinder blank 3 is placed into the outer cylinder liner 4 with the orifice facing upwards, and then 10 ZCuSn10P1 copper alloy mandrels are inserted into one central hole and nine plunger holes in sequence. Finally, an alumina refractory ceramic cover 1 is placed on top. Step 3: First, put the billet assembly into a vacuum furnace for heating and heat preservation. After the heat preservation is completed, cool it out of the furnace and then perform annealing to form a rotor blank. Specifically, the assembled components are placed in a vacuum furnace, the furnace door is closed, and the furnace is evacuated for heating and melting. Before heating, the vacuum degree inside the furnace is ≤5Pa, the heating temperature is 1200℃, and the temperature is held for 2 hours. After cooling with argon, the components are taken out of the furnace. The heated and held billet components are then annealed: the billet components are heated to 700℃, held for 2 hours, and then air-cooled. Step 4: Machining the rotor blank to the specified dimensions to form a copper-steel composite bimetallic rotor; Specifically, the rotor blank, after being impregnated with copper alloy, is machined to the specified dimensions. Example 4

[0029] This embodiment provides a method for preparing a bimetallic rotor made of ZCuPb10Sn10 copper alloy and 45 steel: Step 1: After normalizing the steel billet, it is machined into rotor cylinder blank 3. The outer cylinder liner is machined according to the size of the rotor cylinder blank 3. The copper alloy core rod 2 is prepared according to the size of the plunger hole in the rotor cylinder blank 3. The rotor cylinder blank 3, copper alloy core rod 2 and outer cylinder liner 4 are cleaned. Specifically as follows: First, the steel bars are cut to size according to the specifications (φ160mm×145mm) of the billet (material: 45 steel). Then, the billets are normalized at 700℃ for 5 hours, followed by air cooling. Next, the rotor cylinder blank 3 is machined according to the drawings, including one central plunger through hole and nine peripheral plunger blind holes. Based on the dimensions of the rotor cylinder blank 3, an outer cylinder sleeve 4 made of 45 steel is machined. The inner diameter of the outer cylinder sleeve 4 is 161mm, 1mm larger than the outer diameter of the rotor cylinder blank 3; the inner height of the outer cylinder sleeve 4 is 155mm, 6mm larger than the height of the rotor cylinder blank 3. Then, a copper alloy core rod 2 made of ZCuPb10Sn10 material is machined, including one… The prefabricated copper alloy core rods for the center hole and the 9-pillar plug hole are used. The specifications of the prefabricated copper alloy core rod for the center hole are φ32mm×142mm, which is 0.5mm smaller than the corresponding plunger hole diameter and 0.5mm larger than the corresponding plunger hole height. The specifications of the prefabricated copper alloy core rod for the plunger hole are φ28mm×110mm, which is 0.5mm smaller than the corresponding plunger hole diameter and 3mm larger than the corresponding plunger hole height. Finally, cleaning and degreasing are carried out. First, the processed rotor cylinder blank 3, copper alloy core rod 2, outer cylinder liner 4, etc. are cleaned with 3% sodium hydroxide aqueous solution to remove oil. Then, they are rinsed with clean water until neutral and dried at 60℃ in the welding box for 1 hour. Step 2: First, assemble the cleaned rotor cylinder blank 3 into the outer cylinder liner 4, and then assemble the cleaned copper alloy mandrel 2 into the plunger hole to form a blank assembly. Specifically, the rotor cylinder blank 3 is placed into the outer cylinder liner 4 with the orifice facing upwards. Then, 10 ZCuPb10Sn10 copper alloy mandrels are inserted into one central hole and nine plunger holes in sequence. Finally, an alumina refractory ceramic cover 1 is placed on top. Step 3: First, put the billet assembly into a vacuum furnace for heating and heat preservation. After the heat preservation is completed, cool it out of the furnace and then perform annealing to form a rotor blank. Specifically, the assembled components are placed in a vacuum furnace, the furnace door is closed, and the furnace is evacuated for heating and melting. Before heating, the vacuum degree inside the furnace is ≤5Pa, the heating temperature is 900℃, and the temperature is held for 6 hours. After cooling with argon, the components are taken out of the furnace. The heated and held billet components are then annealed: the billet components are heated to 500℃, held for 6 hours, and then air-cooled. Step 4: Machining the rotor blank to the specified dimensions to form a copper-steel composite bimetallic rotor; Specifically, the rotor blank, after being impregnated with copper alloy, is machined to the specified dimensions. Comparative Example 1

[0030] Traditional bimetallic rotor manufacturing process: Step 1: Steel substrate preparation: Cut steel bars according to the specifications of the processed billet; Step 2, Steel Matrix Machining: Machining the rotor steel cylinder blank, using turning, drilling, milling, boring and other processes according to the drawing requirements, to machine it to the dimensions required by the drawing; Step 3, Surface treatment: This includes steps such as degreasing, pickling, and drying to ensure that cutting fluid, oil, and other contaminants are completely removed from the surface of the steel substrate. Step 4, Casting or Pouring: Melt the copper alloy to the required temperature, ensuring it is completely melted, and then quickly pour it into the center hole of the steel matrix, so that the copper alloy quickly fills the entire cavity under pressure. Step 5, Cooling: After pouring, cool by air cooling or water cooling. After the alloy solidifies, turn off the cooling water and let it cool naturally to room temperature. Step 6, Post-processing: Remove the gate, perform necessary machining and inspection steps to obtain the copper-steel bimetallic rotor.

[0031] The performance of the copper-steel composite bimetallic rotors obtained in the above embodiments and comparative examples was tested, and the performance data are shown in Table 1. Table 1 Performance data of bimetallic products

[0032] As can be seen, the tensile strength of the comparative example is only 198MPa~202MPa; the tensile strength of Examples 1-4 is 279MPa~321MPa, which is about 40%~60% higher than that of the comparative example, and the tensile performance is significantly enhanced. The fracture location of the comparative example is at the joint, indicating that the traditional "copper-steel joint interface" of bimetallic materials is a performance weakness and is prone to fracture at this point under stress. The fracture location of Examples 1-4 is at the copper end, indicating that the strength of the improved joint interface is higher than that of the copper alloy itself, and the reliability of the joint is greatly improved. The hardness of the copper alloy and steel fluctuates little and remains basically stable. Annealing was added in the examples, which can effectively eliminate and homogenize internal stress, optimize material properties, stabilize microstructure, and improve interfacial bonding performance.

[0033] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0034] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A vacuum infiltration method for preparing an integrated copper-steel composite bimetallic rotor, characterized in that, Includes the following steps: Step 1: After normalizing the steel billet, it is machined into a rotor cylinder blank (3). The outer cylinder sleeve (4) is machined according to the size of the rotor cylinder blank (3). The copper alloy core rod (2) is prepared according to the size of the plunger hole in the rotor cylinder blank (3). The rotor cylinder blank (3), the copper alloy core rod (2) and the outer cylinder sleeve (4) are cleaned. Step 2: First, assemble the cleaned rotor cylinder blank (3) into the outer cylinder liner (4), and then assemble the cleaned copper alloy core rod (2) into the plunger hole to form a blank assembly. Step 3: First, put the billet assembly into a vacuum furnace for heating and heat preservation. After the heat preservation is completed, cool it out of the furnace and then perform annealing to form a rotor blank. Step 4: Machin the rotor blank to the specified dimensions to form a copper-steel composite bimetallic rotor.

2. The vacuum infiltration preparation method for the integrated copper-steel composite bimetallic rotor according to claim 1, characterized in that, In step one, the heating temperature for the normalizing treatment is 700℃~1000℃, the holding time is 1h~5h, and the furnace is then air-cooled.

3. The vacuum infiltration preparation method for the integrated copper-steel composite bimetallic rotor according to claim 1, characterized in that, In step one, the inner diameter of the outer cylinder liner (4) is 0.1mm~1mm larger than the outer diameter of the rotor cylinder blank (3), and the inner height of the outer cylinder liner (4) is 2mm~10mm larger than the height of the rotor cylinder blank (3).

4. The vacuum infiltration preparation method for the integrated copper-steel composite bimetallic rotor according to claim 1, characterized in that, In step one, the diameter of the copper alloy mandrel (2) is 0.5mm~1mm smaller than the diameter of the corresponding plunger hole, and the height of the copper alloy mandrel (2) is 0.5mm~5mm larger than the height of the corresponding plunger hole.

5. The vacuum infiltration preparation method for the integrated copper-steel composite bimetallic rotor according to claim 1, characterized in that, In step one, the cleaning process involves first cleaning the rotor cylinder blank (3), copper alloy core rod (2), and outer cylinder liner (4) with sodium hydroxide solution to remove oil, then rinsing with water until neutral, and finally drying.

6. The vacuum infiltration preparation method for the integrated copper-steel composite bimetallic rotor according to claim 1, characterized in that, In step three, the vacuum level inside the vacuum furnace is ≤5Pa.

7. The vacuum infiltration preparation method for the integrated copper-steel composite bimetallic rotor according to claim 1, characterized in that, In step three, the billet assembly is heated to 900℃~1200℃ in a vacuum furnace, and the holding time is 2h~6h.

8. The vacuum infiltration preparation method for the integrated copper-steel composite bimetallic rotor according to claim 1, characterized in that, In step three, the annealing temperature is 500℃~700℃, and the holding time is 2h~6h.

9. The application of a copper-steel bimetallic rotor prepared by the vacuum infiltration method according to any one of claims 1 to 8 in a high-pressure plunger pump or hydraulic motor.

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