Ultrasonic assisted extrusion composite casting device and method for copper-steel bimetallic components

Abstract

The present invention provides an ultrasonic-assisted extrusion composite casting device and method for a copper-steel bimetallic component. The device comprises: an ultrasonic-assisted mechanism, which applies ultrasonic vibration to the melt formed by the steel component or the copper alloy raw material during the process of forming the copper-steel bimetallic component; an extrusion die mechanism, comprising an extrusion upper die and an extrusion lower die matching the copper-steel bimetallic component, wherein the composite formed by the steel component and the melt is placed in the extrusion lower die, and the extrusion upper die and the extrusion lower die are combined to realize the extrusion forming of the copper-steel bimetallic component. The lead-bronze melt is filled and solidified under the action of ultrasound, which effectively inhibits the coarse size of the lead particles, and at the same time cleans the copper-steel solid-liquid interface, creating favorable thermodynamic and kinetic conditions for the metallurgical bonding of the bimetallic interface; under the action of extrusion, the atomic diffusion rate of the alloy elements at the copper-steel interface is accelerated, and the metallurgical bonding quality of the copper-steel interface is improved. The present invention can effectively improve the overall quality of the copper-steel bimetallic component.

Description

Technical Field

[0001] The invention relates to the technical field of heterogeneous metal composite casting, and in particular to an ultrasonic-assisted extrusion composite casting device and method for a copper-steel bimetallic component. Background Art

[0002] Composite casting is the process of casting two or more metal materials with different properties into a complete casting, so that different parts of the casting have different properties to meet the requirements of use. Common methods include inlay casting, gravity and centrifugal composite casting. Copper-steel bimetallic components are mainly used as key components that operate at high speeds and withstand pressure and impact alternating loads, such as: plunger cylinders of hydraulic motors, bearings and sleeves of rotating machinery, etc. For high-end equipment such as heavy engineering machinery, copper-steel bimetallic components are required to withstand higher speeds and greater loads, and lead-bronze alloys with better wear resistance need to be selected. When lead is evenly distributed in fine particles, lead bronze has good self-lubricating properties, which is beneficial to improve wear resistance. However, the lead element in lead bronze neither dissolves in copper nor forms a compound with copper, but exists in a single substance. When the conventional gravity composite melting and casting method is used to prepare copper-steel bimetallic components, due to process limitations, in order to achieve metallurgical bonding at the copper-steel interface, the copper-steel bimetallic matrix is ​​kept at a temperature above the lead bronze liquidus (about 1000°C) for a long time, which easily produces coarse lead particles and leads to extremely uneven distribution of the lead element; and causes phase structure transformation of the steel matrix, resulting in coarse grains and mixed crystal phenomena, which seriously affects the wear resistance and fatigue life of the copper-steel bimetallic components.

[0003] Patent CN114289703A discloses a casting method for a steel-based surface composite high-strength ultra-wear-resistant copper alloy, its composite alloy and application, and the casting method includes: melting the copper alloy and casting it on the surface of a steel substrate that has been surface cleaned and preheated, then keeping the temperature of the steel substrate above 1100°C, and finally taking out the steel substrate for high-frequency vibration and / or centrifugal treatment. It can be judged from the chemical composition of the copper alloy used in this method that the copper alloy belongs to aluminum bronze. This method requires heating the copper alloy and the steel substrate to above 1100°C, and the lead bronze slowly cools and solidifies on the steel substrate at this temperature, resulting in coarse lead particle size, and the steel substrate will undergo phase structure transformation, resulting in coarse grains or mixed crystals. Therefore, this method cannot be used to prepare high-quality bimetallic components of lead bronze and steel.

[0004] Patent CN115194128A discloses a tubular metal clad material extrusion casting direct composite forming equipment and process. The invention combines the extrusion casting process of a single metal tube with the liquid-solid composite process of a layered metal composite material to develop a new technology for extrusion casting direct composite forming of tubular metal clad materials; based on the technology, a new tubular metal clad material extrusion casting direct composite forming equipment is developed. However, the invention is mainly aimed at tubular components and cannot prepare components of other shapes. Summary of the invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide an ultrasonic-assisted extrusion composite casting device and method for a copper-steel bimetallic component.

[0006] According to one aspect of the present invention, there is provided an ultrasonic assisted extrusion composite casting device for a copper-steel bimetallic component, the device comprising:

[0007] An ultrasonic assisting mechanism that applies ultrasonic vibration to a melt formed from a steel component or a copper alloy raw material during the process of forming a copper-steel bimetallic component;

[0008] The extrusion die mechanism comprises an extrusion upper die and an extrusion lower die matching the copper-steel bimetallic component. The composite formed by the steel component and the melt is placed in the extrusion lower die. The extrusion upper die and the extrusion lower die are combined to realize the extrusion forming of the copper-steel bimetallic component.

[0009] Optionally, the ultrasonic auxiliary mechanism includes: an ultrasonic vibration mechanism and an ultrasonic application mechanism matching the copper-steel bimetallic component, the vibration mechanism is used to generate an ultrasonic field, and the ultrasonic application mechanism is used to apply the ultrasonic field to the steel component or the melt formed by the copper alloy raw material.

[0010] Optionally, the parameters of the ultrasonic vibration mechanism include: power of 0.5 kW to 50 kW, and a vibration frequency range of 10 kHz to 100 kHz.

[0011] Optionally, the ultrasonic application mechanism acts directly on the melt formed by the copper alloy raw material through an ultrasonic vibration probe, or acts on the surface of the steel component through an ultrasonic vibration probe to indirectly act on the melt.

[0012] Optionally, the extrusion upper die is installed on a moving template mechanism of the extrusion casting equipment, and the extrusion upper die can move at a set speed; the extrusion lower die is installed on a stationary template mechanism of the extrusion casting equipment.

[0013] Optionally, the extrusion upper die and the extrusion lower die are positioned and clamped by a guiding and positioning mechanism.

[0014] According to another aspect of the present invention, a method for ultrasonically assisted extrusion composite casting of a copper-steel bimetallic component is provided, which is implemented by using the above-mentioned ultrasonically assisted extrusion composite casting device for the copper-steel bimetallic component, and the method comprises:

[0015] After quenching and tempering, the steel components are heated and kept warm in a protective atmosphere heating furnace, and the holding temperature is lower than the solidus temperature of the steel;

[0016] Putting a lead bronze alloy into a crucible, heating and melting the lead bronze alloy in a resistance melting furnace in a protective atmosphere to obtain a lead bronze melt;

[0017] The heat-insulated steel component is moved into a casting chamber with a protective atmosphere, and the lead bronze melt is cast into the concave structure of the steel component to form a composite of the lead bronze melt and the steel component;

[0018] At the beginning of pouring, ultrasonic vibration is applied to the steel component to indirectly act on the melt; or, at the end of pouring, ultrasonic vibration is applied to the liquid surface of the lead bronze melt of the composite to directly act on the melt;

[0019] The composite is placed in an extrusion lower die, and the extrusion casting equipment is started. The extrusion upper die moves at a set speed and closes with the extrusion lower die. The closing state of the extrusion upper die and the extrusion lower die is maintained for a set time. Then, the extrusion upper die moves and separates from the extrusion lower die, and the copper-steel bimetallic component can be taken out to obtain a copper-steel bimetallic component with a preset shape.

[0020] Optionally, the mass percentage of lead element in the lead bronze alloy is 5% to 30%; and the steel component is carbon structural steel or alloy structural steel.

[0021] Optionally, the temperature of the lead bronze melt is 5°C to 150°C above the liquidus temperature.

[0022] Optionally, the clamping state of the extrusion upper die and the extrusion lower die is maintained for a set time, wherein the holding time is 10s to 600s.

[0023] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0024] The ultrasonic-assisted extrusion composite casting device and method for a copper-steel bimetallic component provided by the present invention can effectively suppress the coarse size of lead particles by filling and solidifying the lead-bronze melt under the assistance of ultrasound, thereby obtaining a microstructure with uniform composition and fine size; at the same time, the ultrasonic field can clean and purify the copper-steel solid-liquid interface, creating favorable thermodynamic and kinetic conditions for the metallurgical bonding of the bimetallic interface; and, under the joint action of the extrusion upper die and the extrusion lower die, the atomic diffusion rate of the alloy elements at the copper-steel interface can be accelerated, and the metallurgical bonding quality of the copper-steel interface can be improved, thereby improving the overall quality of the copper-steel bimetallic component. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0026] Figure 1 It is a schematic diagram of the pouring process of the preheated steel component and the molten lead bronze melt in a protective atmosphere pouring chamber in one embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the ultrasonic vibration treatment process after pouring is completed in one embodiment of the present invention;

[0028] Figure 3 The structure of the extrusion upper die in one embodiment of the present invention is schematically shown. Figure 1 ;

[0029] Figure 4 The structure of the extrusion upper die in one embodiment of the present invention is schematically shown. Figure 2 ;

[0030] Figure 5 It is a structural schematic diagram of the extrusion lower die in one embodiment of the present invention;

[0031] Figure 6 It is a schematic diagram of the initial state (before mold closing) of the mold for extrusion composite casting of a copper-steel bimetallic component after ultrasonic vibration treatment in one embodiment of the present invention.

[0032] In the figure: 1 is a steel component, 2 is a lead bronze melt, 3 is a crucible, 4 is an ultrasonic vibration probe, 5 is an extrusion upper die, 5a is a working position where the extrusion upper die contacts with the copper-steel bimetallic component, 6 is an extrusion lower die, and 6a is a position where the copper-steel bimetallic component is placed in the extrusion lower die. DETAILED DESCRIPTION

[0033] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0034] In view of the shortcomings of conventional gravity composite casting technology for copper-steel bimetallic components, especially for the composite casting process of lead bronze and steel, there is an urgent need for a new composite casting device and method to achieve interfacial metallurgical bonding of lead bronze and steel, which can avoid the coarse lead particle size in lead bronze and the phase transformation of the steel matrix, so as to improve the overall quality of copper-steel bimetallic components.

[0035] Reference Figure 1-Figure 6An ultrasonic-assisted extrusion composite casting device for a copper-steel bimetallic component provided by an embodiment of the present invention comprises an ultrasonic-assisted mechanism and an extrusion die mechanism, wherein: the ultrasonic-assisted mechanism applies ultrasonic vibration to a steel component 1 or a melt formed by a copper alloy raw material during the process of forming the copper-steel bimetallic component, so as to refine the copper alloy grains and promote the metallurgical bonding of the copper-steel interface; the extrusion die mechanism comprises an extrusion upper die 5 and an extrusion lower die 6 matching the copper-steel bimetallic component, a composite formed by the steel component 1 and the melt is placed in the extrusion lower die 6, the extrusion upper die 5 and the extrusion lower die 6 are combined to realize the extrusion forming of the copper-steel bimetallic component, and further promote the metallurgical bonding of the copper-steel interface.

[0036] In the embodiment of the present invention, an ultrasonic-assisted mechanism is used to allow the melt (lead bronze melt 2) formed by the copper alloy raw material to be filled and solidified under the assistance of ultrasound, which can effectively refine the grain size of the copper-rich primary crystal (dendrite), thereby suppressing the coarse size of the lead particles and obtaining a microstructure with uniform composition and fine size; at the same time, the ultrasonic field can clean and purify the copper-steel solid-liquid interface, creating favorable thermodynamic and kinetic conditions for the metallurgical bonding of the bimetallic interface; and, under the joint action of the extrusion upper die 5 and the extrusion lower die 6, the atomic diffusion rate of the alloy elements at the copper-steel interface can be accelerated, and the metallurgical bonding quality of the copper-steel interface can be improved, thereby improving the overall quality of the copper-steel bimetallic component.

[0037] In some embodiments, the ultrasonic assisting mechanism includes: an ultrasonic vibration mechanism and an ultrasonic applying mechanism matched with the copper-steel bimetallic component, the vibration mechanism is used to generate an ultrasonic field, and the ultrasonic applying mechanism is used to apply the ultrasonic field to the steel component 1 or the melt formed by the copper alloy raw material, thereby applying the ultrasonic field directly or indirectly to the copper alloy melt.

[0038] In some embodiments, the parameters of the ultrasonic vibration mechanism include: power of 0.5 kW to 50 kW, and a vibration frequency range of 10 kHz to 100 kHz. The selection of ultrasonic parameters should comprehensively consider factors such as the quality of the lead bronze melt, the cross-sectional area of ​​the lead bronze melt in different directions, and the solidification time of the lead bronze melt, to ensure that all parts of the lead bronze melt are subjected to the ultrasonic vibration.

[0039] In order to apply an ultrasonic field to the copper alloy melt to refine the melt grains, in some embodiments, the ultrasonic application mechanism directly acts on the melt formed by the copper alloy raw material through the ultrasonic vibration probe 4, or indirectly acts on the surface of the steel component 1 and then acts on the melt.

[0040] In some embodiments, the extrusion upper die 5 is designed and manufactured according to the copper-steel bimetallic component, which is installed on the moving template mechanism of the extrusion casting equipment, and the extrusion upper die 5 can move at a set speed; the extrusion lower die 6 is designed and manufactured according to the copper-steel bimetallic component, which is installed on the stationary template mechanism of the extrusion casting equipment, and the closing and opening of the extrusion lower die 6 are realized by the movement of the extrusion upper die 5. In the process of closing the mold, by setting the movement speed of the extrusion upper die 5, it is ensured that the extrusion upper die 5 is steadily pressed to the upper surface of the melt while closing the mold quickly, so that it is not subjected to a large impact. When performing extrusion composite casting, the copper-steel bimetallic component is placed as a whole in the cavity of the extrusion lower die 6, and the extrusion upper die 5 is pressed toward the extrusion lower die 6 at a certain speed, and closes the mold with the extrusion lower die 6 to realize the extrusion forming of the copper-steel bimetallic component.

[0041] Exemplarily, the upper surface of the extrusion lower die 6 includes a portion 6a where the copper-steel bimetallic component is placed, which is recessed downward, and a composite formed by the steel component 1 and the melt is placed at this portion; the lower surface of the extrusion upper die 5 includes a working portion 5a where the extrusion upper die contacts the copper-steel bimetallic component, and the working portion is a protruding structure, which vertically enters the recessed structure of the extrusion lower die 6 during extrusion die closing, and the portion 6a where the copper-steel bimetallic component is placed on the extrusion lower die and the working portion 5a where the extrusion upper die contacts the copper-steel bimetallic component are adapted to the shape and size of the copper-steel bimetallic component.

[0042] In some embodiments, the extrusion upper die 5 and the extrusion lower die 6 are positioned and clamped by a guide positioning mechanism, and the two can accurately position and clamp the mold to achieve extrusion forming of the copper-steel bimetallic component. The guide positioning mechanism is implemented using existing technology, and exemplarily, a guide column type guide positioning mechanism is used.

[0043] Another embodiment of the present invention provides a method for ultrasonically assisted extrusion composite casting of a copper-steel bimetallic component, which is implemented by using the above-mentioned ultrasonically assisted extrusion composite casting device for the copper-steel bimetallic component. Figure 1-Figure 6 , the method comprising:

[0044] S1, after the quenching and tempering treatment, the steel component 1 is subjected to surface cleaning treatment and then heated and kept warm in a protective atmosphere heating furnace, the holding temperature being lower than the solidus temperature of the steel to avoid phase transformation of the steel; the protective atmosphere can be nitrogen, argon, etc.;

[0045] S2, placing the lead bronze alloy into a crucible 3 such as a graphite crucible, heating and melting the lead bronze alloy in a resistance melting furnace in a protective atmosphere to obtain a lead bronze melt 2;

[0046] In this step, the mass of the lead-bronze alloy required to prepare one copper-steel bimetallic component is determined based on the target copper-steel bimetallic component; then, the mass of the lead-bronze alloy that needs to be melted can be further determined based on the number of copper-steel bimetallic components.

[0047] S3, moving the insulated steel component 1 into a casting chamber with a protective atmosphere, and pouring the lead bronze melt 2 into the concave structure of the steel component 1 to form a composite of the lead bronze melt 2 and the steel component 1;

[0048] After the lead bronze melt 2 is poured into the concave structure of the steel component 1, it solidifies at the position of the concave structure, so the internal space of the concave structure is finally occupied by the copper alloy. During the pouring process, a quantitative tool is used to determine the mass of the lead bronze melt 2 added; or, the position of the lead bronze melt 2 is observed during pouring, and the pouring is stopped when it reaches the top of the concave structure.

[0049] S4. At the beginning of pouring, ultrasonic vibration is applied to the steel component 1 to indirectly act on the lead bronze melt 2; or, at the end of pouring, ultrasonic vibration is applied to the liquid surface of the lead bronze melt 2 of the composite to directly act on the melt;

[0050] S5. Place the composite body into the extrusion lower die 6, start the extrusion casting equipment, move the extrusion upper die 5 at a set speed, close the die with the extrusion lower die 6, and keep the close state of the extrusion upper die 5 and the extrusion lower die 6 for a set time. Then, move the extrusion upper die 5 and separate from the extrusion lower die, open the mold, take out the copper-steel bimetallic component, and obtain a copper-steel bimetallic component with a preset shape, whose shape is determined according to the structural requirements of the mechanical parts.

[0051] In some embodiments, the copper alloy refers to a lead bronze alloy, and the mass percentage of the lead element in the lead bronze alloy is 5% to 30% to meet the performance requirements of the target parts; the steel component 1 is a carbon structural steel or an alloy structural steel to meet the requirements of copper-steel bimetallic components for different occasions. In addition, the structural steel has been quenched and tempered, and the microstructure has met the use requirements, and the subsequent processes will not have a significant impact on the microstructure of the steel.

[0052] The temperature of the lead bronze melt 2 mainly considers the lead particle size and the copper alloy matrix grain size. The higher the temperature, the larger the sizes of the two. In some embodiments, the temperature of the lead bronze melt 2 is 5°C to 150°C above the liquidus temperature. According to the specific structural dimensions of the copper-steel bimetallic component, a lower temperature is selected as much as possible to facilitate grain refinement, thereby improving the wear resistance and fatigue life of the bimetallic component.

[0053] The ultrasonic applying mechanism can act directly on the surface of the liquid lead bronze through the ultrasonic vibration probe 4, or can act indirectly on the steel surface through the ultrasonic vibration probe 4. For example, after the pouring is completed, the activated ultrasonic vibration probe 4 is inserted into the lead bronze liquid surface to apply ultrasonic vibration.

[0054] If ultrasonic vibration is not used, bubbles and non-metallic inclusions will be generated at the copper-steel interface during the melt filling and solidification process, resulting in slow copper-steel interface bonding speed and poor bonding quality. The above embodiment of the present invention uses ultrasonic vibration to effectively remove bubbles and inclusions at the interface and promote interface atomic diffusion. Since the copper-steel interface is cleaned by ultrasonic vibration, the temperature of the lead bronze melt can be appropriately reduced.

[0055] In some embodiments, the clamping state of the extrusion upper mold 5 and the extrusion lower mold 6 is maintained for a set time, wherein the holding time is 10s to 600s.

[0056] Experiments show that for bimetallic components of lead bronze and steel, using the device and method in the above embodiments of the present invention, the average size of lead particles is refined from more than 100 μm in the conventional gravity composite melting and casting method to less than 50 μm; the copper-steel interface tensile strength is increased from about 160 MPa in the conventional gravity composite melting and casting method to about 210 MPa, and the interface tensile strength is close to or even exceeds the tensile strength of the lead bronze alloy.

[0057] The device and method provided by the above embodiment of the present invention are applicable to cylinder-type copper-steel bimetallic components, where the steel component has a concave structure and the copper alloy is compounded on the concave structure, so that it can be applicable to the preparation of copper-steel bimetallic components of various shapes. The above embodiment of the present invention comprehensively utilizes the technical advantages of ultrasonic-assisted technology and extrusion composite casting process. Ultrasonic vibration can remove bubbles and non-metallic inclusions at the copper-steel interface, promote atomic diffusion at the copper-steel interface, greatly shorten the required residence time of lead bronze above the liquidus temperature, control the preheating temperature of the steel below the phase change temperature, and obtain a lead bronze microstructure and lead particle distribution with uniform composition and fine size; it can avoid the coarse grains and mixed crystal phenomenon caused by phase transformation of the steel matrix; and improve the metallurgical bonding quality of the copper-steel interface.

[0058] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. A method for ultrasonically assisted extrusion composite casting of a copper-steel bimetallic component, which is implemented using an ultrasonically assisted extrusion composite casting device for a copper-steel bimetallic component, characterized in that: The device comprises: An ultrasonic auxiliary mechanism, wherein the ultrasonic auxiliary mechanism directly applies ultrasonic vibration to a melt formed by a copper alloy raw material during the process of forming a copper-steel bimetallic component, wherein the copper alloy raw material is a lead bronze alloy, and the mass percentage of lead in the lead bronze alloy is 5% to 30%; An extrusion die mechanism comprises an extrusion upper die and an extrusion lower die matching the copper-steel bimetallic component, a composite formed by the steel component and the melt is placed in the extrusion lower die, and the extrusion upper die and the extrusion lower die are combined to realize the extrusion forming of the copper-steel bimetallic component; The method comprises: After quenching and tempering, the steel components are heated and kept warm in a protective atmosphere heating furnace, and the holding temperature is lower than the solidus temperature of the steel; Putting a lead bronze alloy into a crucible, heating and melting the lead bronze alloy in a resistance melting furnace in a protective atmosphere to obtain a lead bronze melt; the temperature of the lead bronze melt is 5° C. to 150° C. above the liquidus temperature; The heat-insulated steel component is moved into a casting chamber with a protective atmosphere, and the lead bronze melt is cast into the concave structure of the steel component to form a composite of the lead bronze melt and the steel component; during the casting process, a quantitative tool is used to determine the mass of the lead bronze melt added; or, during the casting process, the position of the lead bronze melt is observed, and the casting is stopped when the lead bronze melt reaches the top of the concave structure of the steel component; At the end of pouring, ultrasonic vibration is applied to the lead bronze melt of the composite body to directly act on the melt; the parameters of the ultrasonic auxiliary mechanism include: power of 0.5 kW to 50 kW, and vibration frequency range of 10 kHz to 100 kHz; The composite is placed in an extrusion lower die, and the extrusion casting equipment is started. The extrusion upper die moves at a set speed and closes with the extrusion lower die. The closing state of the extrusion upper die and the extrusion lower die is maintained for a set time, and the holding time is 10 s to 600 s. Then, the extrusion upper die moves and separates from the extrusion lower die, and the copper-steel bimetallic component can be taken out to obtain a copper-steel bimetallic component with a preset shape.

2. The ultrasonic-assisted extrusion composite casting method for copper-steel bimetallic components according to claim 1 is characterized in that: The steel component is carbon structural steel or alloy structural steel.

3. The ultrasonic-assisted extrusion composite casting method for copper-steel bimetallic components according to claim 1 is characterized in that: The ultrasonic auxiliary mechanism includes: an ultrasonic vibration mechanism and an ultrasonic application mechanism matched with the copper-steel bimetallic component, the vibration mechanism is used to generate an ultrasonic field, and the ultrasonic application mechanism is used to apply the ultrasonic field to the melt formed by the copper alloy raw material.

4. The ultrasonic-assisted extrusion composite casting method for copper-steel bimetallic components according to claim 3 is characterized in that: The ultrasonic applying mechanism directly acts on the melt formed by the copper alloy raw material through an ultrasonic vibration probe.

5. The ultrasonic-assisted extrusion composite casting method for copper-steel bimetallic components according to claim 1 is characterized in that: The extrusion upper die is installed on a moving template mechanism of the extrusion casting equipment, and the extrusion upper die can move at a set speed; the extrusion lower die is installed on a stationary template mechanism of the extrusion casting equipment.

6. The ultrasonic-assisted extrusion composite casting method for copper-steel bimetallic components according to claim 1 is characterized in that: The extrusion upper die and the extrusion lower die are positioned and clamped by a guiding and positioning mechanism.

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