Melting and casting process for producing bimetal hydraulic rotor through continuous furnace

Abstract

The invention discloses a casting process for producing a bimetal hydraulic rotor by a continuous furnace, which comprises the following steps of: cleaning casting surfaces of a steel substrate and a copper block, and placing the copper block in a copper liquid melting pool at the top of the steel substrate; covering the steel matrix solution copper pool with a heat preservation cover body made of a heat preservation material, then feeding the steel matrix solution copper pool into a continuous furnace, and performing heating, heat preservation and cooling along with the furnace according to a set casting temperature T and a set moving speed r to obtain the copper-steel bimetal rotor; wherein the heating, heat preservation and cooling processes are carried out under the protective atmosphere, in the heating process, heat is transferred to the copper block through the steel base body, and the copper block is melted; in the cooling process, under the heat preservation effect of the heat preservation cover body, heat of molten copper is transferred through the steel base body for cooling, and the solidification direction is from bottom to top; according to the method, the copper liquid is solidified in a sequential solidification mode, so that excellent metallurgical bonding at the bimetal composite interface is guaranteed, and the bonding strength is improved.

Description

Technical Field

[0001] The invention relates to the technical field of bimetallic hydraulic rotor melting and casting technology, and in particular to a melting and casting technology for producing bimetallic hydraulic rotors in a continuous furnace. Background Art

[0002] In the field of modern manufacturing, copper and steel are two important metal materials, each with unique properties and application areas. Copper has good electrical and thermal conductivity, so it is often used in electronic equipment, wires and cables, heat conductors and other fields. Steel has excellent mechanical properties and is widely used in the manufacture of structural parts, mechanical parts, automotive parts, etc. However, some applications require the performance of both copper and steel, and a single material often cannot meet these requirements. Copper-steel bimetallic materials came into being. It combines the advantages of copper and steel, has high thermal conductivity, high strength and good mechanical properties, and can be used in high-demand electronic equipment coolers, chemical equipment, marine engineering and other fields.

[0003] The copper-steel bimetallic rotor is an engineering structural part with a wide range of applications. The bimetallic hydraulic rotor is usually in the form of copper-steel composite. The melting point of copper is lower than that of steel, so that the copper melts and covers the surface of the steel to form a metallurgical bond, thereby achieving the purpose of the composite of the two. In industrial production, a melting furnace is usually used for the composite of the two, that is, a copper block is placed on the upper end of the cylinder body and put into the furnace together. Then the copper block is melted and forms a metallurgical bond with the steel cylinder body below. However, due to the large volume of the cylinder body, the temperature drop of the cylinder body during the cooling process is lower than that of the copper layer with a thickness of only 4-6mm, so that there is always a heat source at the bottom of the copper layer. During the solidification process, the temperature of the copper liquid at the copper-steel interface is always higher than the temperature of the copper liquid above it, resulting in a large solidification shrinkage tendency at the copper-steel interface, causing early failure of components and affecting the use of components. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a melting and casting process for producing bimetallic hydraulic rotors in a continuous furnace, in which a steel matrix molten copper pool is covered with a heat-insulating material in a certain structure, and the furnace is heated, insulated and cooled according to a certain melting and casting temperature T and a moving rate r, so that the copper liquid solidifies in a sequential solidification manner to ensure excellent metallurgical bonding at the bimetallic composite interface and improve the bonding strength.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect of the present invention, a continuous furnace casting process for producing a bimetallic hydraulic rotor is provided, comprising:

[0007] The casting surfaces of the steel substrate and the copper block are cleaned, and the copper block is placed in the copper liquid pool on the top of the steel substrate;

[0008] The copper pool of the steel matrix solution is covered with a heat-insulating cover made of heat-insulating material, and then sent into a continuous furnace, and heated, insulated and cooled with the furnace according to the set melting temperature T and moving speed r to obtain a copper-steel bimetallic rotor;

[0009] Among them, the heating, insulation and cooling processes are carried out under a protective atmosphere. During the heating process, heat is transferred to the copper block through the steel matrix to melt the copper block; during the cooling process, the copper liquid is cooled by heat transfer through the steel matrix under the insulation effect of the insulation cover, and the solidification direction is from bottom to top.

[0010] In some embodiments of the present invention, the thermal conductivity of the thermal insulation material is smaller than the thermal conductivity of air.

[0011] In some embodiments of the present invention, the steel substrate and the copper block both have a cylindrical structure, and during melting and casting, the copper block is placed in a copper liquid pool on the upper end surface of the steel substrate.

[0012] In some embodiments of the present invention, the insulation cover body is in a cylindrical structure, a circular groove is arranged in the insulation cover body, a step surface is arranged in the circular groove, and when the insulation cover body is covered on the steel substrate, the step surface is in contact with the upper end surface of the steel substrate.

[0013] In some embodiments of the present invention, a copper block melting space is formed between the upper end surface of the steel substrate and the inner wall surface of the thermal insulation cover.

[0014] In some embodiments of the present invention, the melting and casting temperature T is 1010° C.-1030° C., and the moving rate r is 50 mm / min-70 mm / min.

[0015] In some embodiments of the present invention, the heating temperature is 1010° C.-1030° C., the heating time is 60 min-84 min, and the cooling method is integrated environmental cooling.

[0016] In some embodiments of the present invention, the thermal insulation material is a mixture of modified floating beads and silicic acid.

[0017] In some embodiments of the present invention, the copper block is a copper alloy, and the material of the copper alloy is CuSn 10 Pb 10 The chemical composition by mass percentage includes: Sn: 7.25-7.85%, Pb: 14.1-17.26%, Ni: 1.24-1.86%, Zn: 0.01-0.05% and P: less than 0.1%, and the metallographic structure is α-Cu + spherical rod-shaped Pb.

[0018] In some embodiments of the present invention, the steel matrix is ​​an alloy steel, the alloy steel material is 42CrMoS4, and the chemical composition by mass percentage includes: C: 040-0.45%, Si≤0.40%, Mn: 060-0.90%, P≤0.025%, S: 0.010-0.018%, Cr 0.90-1.20%, Mo 0.15-0.30%, Cu≤0.20% and Ni≤0.30%, and the metallographic structure is pearlite + ferrite.

[0019] One or more technical solutions of the present invention have the following beneficial effects:

[0020] The invention provides a continuous furnace casting process for producing bimetallic hydraulic rotors. A heat-insulating material is covered on a steel substrate and a copper block in a certain structure. The material is heated, insulated and cooled with the furnace according to a certain casting temperature T and a moving rate r, so that the copper liquid solidifies in a sequential solidification manner, wherein the moving rate is related to the heating time and the cooling time. Based on the cause of shrinkage of the copper layer, only by changing its solidification direction can the excellent metallurgical bonding at the bimetallic composite interface be guaranteed. Therefore, only by reducing the heat dissipation of the upper end of the copper liquid, a heat-insulating cover is covered on the steel substrate and the copper block, so that the solidification mode of the copper liquid is sequential solidification, and the shrinkage defect at the interface is effectively eliminated.

[0021] The invention provides a continuous furnace for producing a bimetallic hydraulic rotor. The invention can effectively cover the copper molten pool on the upper end of the steel substrate and the copper liquid in the copper molten pool by providing a heat-insulating cover body, thereby achieving heat preservation, changing the solidification mode of the copper liquid, and ensuring excellent metallurgical bonding at the bimetallic composite interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of the heat-insulating cover of the present invention;

[0023] Figure 2 This is a dimensional diagram of the thermal insulation cover in Example 1 of the present invention;

[0024] Figure 3 This is a schematic diagram of the temperature measurement position in Example 1 of the present invention;

[0025] Figure 4 This is a temperature measurement curve diagram of Example 1 of the present invention;

[0026] Figure 5 The cross-sectional view of the copper layer of the cylinder body obtained by conventional melting and casting and the melting and casting process of the present invention is shown in FIG.

[0027] In the figure: 1. thermal insulation cover; 101. circular groove; 102. step surface; 2. temperature sensor; 3. steel substrate. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0029] During the copper-steel bimetallic casting process, when the copper liquid solidifies, the temperature of the lower end of the copper liquid is higher than that of the upper end due to the large volume of the steel matrix it contacts, causing the copper liquid to solidify from top to bottom. The last solidified area cannot be effectively compensated for shrinkage, and this area happens to be the composite interface required by the copper-steel bimetallic, resulting in a relatively large shrinkage tendency at the copper-steel junction, which reduces the bonding strength.

[0030] To this end, in a typical embodiment of the present invention, a continuous furnace casting process for producing a bimetallic hydraulic rotor is provided, comprising:

[0031] (1) cleaning the casting surfaces of the steel substrate and the copper block, and placing the copper block in a copper liquid molten pool on the top of the steel substrate;

[0032] By cleaning the casting surface of the steel matrix and the copper block, the metal oxides on the surface of the steel matrix and the copper block can be removed, which not only purifies the surface of the steel matrix, but also plays a role in heat preservation, anti-oxidation and fluxing of copper alloy.

[0033] (2) The copper pool of the steel matrix solution is covered with an insulating cover made of an insulating material, and then sent into a continuous furnace, where it is heated, insulated, and cooled along with the furnace according to the set melting temperature T and moving speed r to obtain a copper-steel bimetallic rotor.

[0034] Specifically, the heating, insulation and cooling processes are carried out under a protective atmosphere. During the heating process, heat is transferred to the copper block through the steel matrix to melt the copper block. The melting of the copper block starts preferentially from the contact position with the steel to facilitate the wetting and spreading of the molten copper. During the cooling process, the molten copper is isolated from impurities in the external furnace body entering the molten copper under the insulation effect of the insulation cover, thereby ensuring the purity of the molten copper. On the other hand, heat is transferred through the steel matrix for cooling, and the solidification direction of the molten copper is from bottom to top, thereby reducing the risk of solidification defects occurring at the composite interface.

[0035] In this embodiment, the thermal conductivity of the insulation material is lower than that of air, i.e., lower than 0.023 W / (m·K). The insulation material with extremely low thermal conductivity is used to isolate the copper part of the cylinder from the cold atmosphere in the heating furnace, so that the heat of the molten copper is finally conducted out through the steel matrix. The large volume of the steel matrix and the slow temperature drop are used to minimize the temperature gradient in the molten copper, so that the molten copper reaches the solidus temperature almost at the same time, and the solidification direction of the molten copper in the original casting process is changed from top to bottom to bottom to top.

[0036] Since this embodiment is proposed for a copper-steel bimetallic hydraulic rotor, the steel substrate and the copper block both adopt a cylindrical structure. During melting and casting, the copper block is placed in the copper liquid pool on the upper end surface of the steel substrate.

[0037] like Figure 1 As shown, the heat preservation cover body 1 is a cylindrical structure, a circular groove 101 is arranged in the heat preservation cover body, and a step surface 102 is arranged in the circular groove. Figure 2 As shown, when the heat-insulating cover 1 covers the steel substrate 3, the step surface 102 fits with the upper end surface of the steel substrate. This structure fully ensures the sealing of the copper molten pool on the one hand, and on the other hand, the structural design is universal. If the cylinder size changes, only the cover diameter needs to be changed accordingly.

[0038] Furthermore, a copper block melting space is formed between the upper end surface of the steel substrate and the inner wall surface of the insulation cover body, and the insulation cover body can better cover the copper liquid molten pool on the upper end of the steel substrate in all directions, thereby achieving better insulation of the copper solution pool and the copper liquid in the pool.

[0039] In this embodiment, the melting temperature T is 1010° C.-1030° C., and the moving rate r is 50 mm / min-70 mm / min.

[0040] In this embodiment, the heating temperature (i.e., the casting temperature) is 1010°C-1030°C, the heating time is 60min-84min, and the cooling method is integral ambient cooling. During the cooling process, the cylinder body enters an atmosphere with an ambient temperature of 25-32°C from an atmosphere with an ambient temperature of 1010°C-1030°C, and the cylinder body begins to exchange heat violently with the outside world. Due to the presence of the thermal insulation cover, the heat exchange between the copper liquid and the outside world is blocked, and its heat can only be transmitted from the lower end of the cylinder body to the outside world.

[0041] In this embodiment, the thermal insulation material is a mixture of modified floating beads and silicic acid. This thermal insulation material has the characteristics of low cost and is widely used in the foundry industry.

[0042] In this embodiment, the copper block is a copper alloy, and the material of the copper alloy is CuSn 10 Pb 10 , the chemical composition by mass percentage includes: Sn: 7.25-7.85%, Pb: 14.1-17.26%, Ni: 1.24-1.86%, Zn: 0.01-0.05% and P: less than 0.1%, and the metallographic structure is α-Cu + spherical rod-shaped Pb;

[0043] Furthermore, the steel matrix is ​​alloy steel, the alloy steel material is 42CrMoS4, and the chemical composition by mass percentage includes: C: 040-0.45%, Si≤0.40%, Mn: 060-0.90%, P≤0.025%, S: 0.010-0.018%, Cr0.90-1.20%, Mo 0.15-0.30%, Cu≤0.20% and Ni≤0.30%, and the metallographic structure is pearlite + ferrite.

[0044] In this embodiment, CuSn is selected 10 Pb 10 The alloy copper and 42CrMoS4 alloy steel are used as raw materials for preparing bimetallic rotors. On the one hand, CuSn 10 Pb 10 It can play a self-lubricating role, reducing the friction between the rotor and its friction pair. On the other hand, the tensile strength of 42CrMoS4 in normalized and quenched and tempered states can reach ≥820MPa, fully meeting the performance requirements of hydraulic pumps and motors. In addition, 42CrMoS4 has a high sulfur content, which improves its cutting performance and reduces the cost of the processing process.

[0045] Example 1

[0046] The outer dimensions of the steel substrate are Φ125*102mm, the number of copper blocks is 3, the size is Φ37*20, the thermal insulation material is a mixture of modified floating beads and silicate, the thermal conductivity is 0.02W / (m·K), and the size is as follows Figure 2 shown.

[0047] After cleaning the casting surfaces of the steel substrate and the copper block, three copper blocks are placed in the copper solution pool on the upper end surface of the steel substrate, and an insulating cover made of insulating material is covered on top of the steel substrate and the copper block, and then sent into a continuous furnace; the casting temperature is 1030°C and the mesh belt speed is 50mm / min.

[0048] The temperature of the cylinder body is measured during the casting process. The temperature measurement position is as follows: Figure 3 As shown, they are near the copper layer and 1 / 2 of the cylinder height direction. The cylinder test position is at 1 / 2 of the cylinder steel wall thickness. The temperature curve of the cylinder steel part and the temperature curve of the copper part during the cooling process are as follows Figure 4 As shown in the figure, it can be seen that during the cooling process, the temperature near the copper layer is always higher than the temperature at 1 / 2 of the cylinder height, indicating that the heat of the copper liquid is conducted through the steel part below. No shrinkage defects were found at the interface of the copper layer of the cylinder after casting, such as Figure 5 As shown, the left one is produced by conventional melting and casting, and the right one is produced by the melting and casting process of the present invention. It can be seen from the figure that there is a large range of solidification shrinkage in the copper layer produced by conventional melting and casting (in the red circle), while no solidification shrinkage is found in the copper layer produced by the present invention.

[0049] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A continuous furnace casting process for producing bimetallic hydraulic rotors, characterized in that: include: The steel substrate and the casting surface of the copper block are cleaned, and the copper block is placed in the copper liquid pool on the top of the steel substrate; The copper pool of the steel matrix solution is covered with a heat-insulating cover made of heat-insulating material, and then sent into a continuous furnace, and heated, insulated and cooled with the furnace according to the set melting temperature T and moving speed r to obtain a copper-steel bimetallic rotor; Among them, the heating, insulation and cooling processes are carried out under a protective atmosphere. During the heating process, heat is transferred to the copper block through the steel matrix to melt the copper block; during the cooling process, the copper liquid is cooled by heat transfer through the steel matrix under the insulation effect of the insulation cover, and the solidification direction is from bottom to top.

2. The continuous furnace casting process for producing bimetallic hydraulic rotors according to claim 1, characterized in that: The thermal conductivity of the heat-insulating material is smaller than that of air.

3. The continuous furnace casting process for producing bimetallic hydraulic rotors according to claim 1, characterized in that: The steel substrate and the copper block both adopt a cylindrical structure. During melting and casting, the copper block is placed in a copper liquid molten pool on the upper end surface of the steel substrate.

4. The continuous furnace casting process for producing bimetallic hydraulic rotors as claimed in claim 3, characterized in that: The heat-insulating cover body is in a cylindrical structure. A circular groove is arranged in the heat-insulating cover body. A step surface is arranged in the circular groove. When the heat-insulating cover body is covered on a steel substrate, the step surface fits with the upper end surface of the steel substrate.

5. The continuous furnace casting process for producing bimetallic hydraulic rotors according to claim 4, characterized in that: A copper block melting space is formed between the upper end surface of the steel base and the inner wall surface of the heat-insulating cover.

6. The continuous furnace casting process for producing bimetallic hydraulic rotors according to claim 1, characterized in that: The melting and casting temperature T is 1010° C.-1030° C., and the moving rate r is 50 mm / min-70 mm / min.

7. The continuous furnace casting process for producing bimetallic hydraulic rotors according to claim 1, characterized in that: The heating temperature is 1010° C.-1030° C., the heating time is 60 min-84 min, and the cooling method is integral environmental cooling.

8. The continuous furnace casting process for producing bimetallic hydraulic rotors according to claim 1, characterized in that: The thermal insulation material is a mixture of modified floating beads and silicic acid.

9. The continuous furnace casting process for producing bimetallic hydraulic rotors according to claim 1, characterized in that: The copper block is a copper alloy, and the material of the copper alloy is CuSn 10 Pb 10 The chemical composition by mass percentage includes: Sn: 7.25-7.85%, Pb: 14.1-17.26%, Ni: 1.24-1.86%, Zn: 0.01-0.05% and P: less than 0.1%, and the metallographic structure is α-Cu + spherical rod-shaped Pb.

10. The continuous furnace casting process for producing bimetallic hydraulic rotors according to claim 1, characterized in that: The steel matrix is ​​alloy steel, the alloy steel material is 42CrMoS4, and the chemical composition by mass percentage includes: C: 040-0.45%, Si≤0.40%, Mn: 060-0.90%, P≤0.025%, S: 0.010-0.018%, Cr 0.90-1.20%, Mo 0.15-0.30%, Cu≤0.20% and Ni≤0.30%, and the metallographic structure is pearlite+ferrite.

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