A melting and casting method for improving the quality consistency of copper-steel bimetal cylinder

Abstract

The application provides a melting and casting method for improving the quality consistency of copper-steel bimetal cylinder, and belongs to the technical field of pump body part machining, which comprises the following steps: uniformly placing a plurality of groups of steel matrix and copper alloy into a melting and casting equipment to perform heating and melting and casting until the end of heat preservation; the heating comprises two-stage heating and heat preservation; cooling is performed after the end of heat preservation to obtain a copper-steel bimetal cylinder. According to the method, the heating stage is divided, especially the first-stage heating temperature is controlled below the liquidus temperature of the copper alloy, so that the liquid state time difference between the inner and outer layers of the cylinder is greatly reduced; when the second-stage heating is performed, different cylinders are at the same temperature starting point again, the difference in the cylinder temperature uniform time in the heating process is reduced, the uniformity of the melting and casting quality between the cylinders is effectively improved, and the qualified rate of product machining is improved; the method is simple in operation, reasonable in design, high in production efficiency, low in production cost and wide in application range.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pump body part processing, and relates to a melting and casting method for improving the quality consistency of copper-steel bimetallic cylinder bodies. BACKGROUND

[0002] Steel is one of the most widely used metal materials at present, and its composite with different materials can form different kinds of composite materials. For example, the composite of steel and copper and copper alloy can obtain copper-steel composite material, which has the ductility, friction reduction, and electric and thermal conductivity of copper on the basis of the performance of steel material, and the advantages of the two are complementary, thus having good application prospects. The copper-steel bimetallic composite material can be widely used in wear-resistant and impact-resistant application scenarios due to its unique material characteristics, and its typical application scenario is used for a hydraulic cylinder body. The cylinder body is one of the key core parts of a plunger pump, and its performance and quality will directly affect the transmission efficiency and service life of the plunger pump.

[0003] At present, one of the commonly used methods for producing copper-steel bimetallic cylinder bodies is melting and casting method. In this method, steel material is used as the base body, a molten pool groove is processed first, and then copper alloy is placed in the molten pool groove. By utilizing the difference in melting points of copper and steel, the copper is placed in a heating furnace to be cladded on the surface of the steel base body, and after cooling, a bimetallic cylinder body is formed. This method has the advantages of high production efficiency and low production cost. When the copper-steel bimetallic cylinder body is produced by melting and casting, the melting and casting furnace or heating furnace used is usually a box-type furnace. A certain number of cylinder bodies are distributed and placed on a tray. Due to the different placement positions, there is a difference in temperature between the cylinder bodies. Generally, the heating speed of the outer layer cylinder body is greater than that of the inner layer cylinder body, so that the time for the outer layer cylinder body to be in a high temperature state is greater than that of the inner layer cylinder body, thereby causing the difference in the organization and performance between the inner and outer layer cylinder bodies. Especially, the heating process includes the melting and solidification process of the copper alloy, which is easy to affect the micro performance of the copper alloy, so that the quality of the same batch of cylinder bodies is inconsistent.

[0004] CN 110434315A discloses a heating and cooling method for steel-copper bimetal cylinder body casting, which comprises steel base body casting surface treatment, preheating, phased heating, variable speed cooling and auxiliary crystallization steps. The preheating and phased heating steps comprise: conveying the steel base body and copper alloy to the preheating area of the casting furnace, preheating at a temperature of 800-950℃, then moving to the heating area for phased heating and holding, the phased heating is divided into three stages, the first stage heating temperature is 900-1050℃, the second stage heating temperature is 1050-1150℃, and the third stage heating temperature is 1050-1120℃, and finally variable speed cooling is performed, which is achieved by different cooling media or combinations to realize fast cooling, medium speed cooling, slow cooling and other cooling modes. The focus of this patent is to install a cap to form a temperature gradient in the copper liquid, so that the copper liquid solidification preferentially occurs at the interface, but it does not consider the temperature difference between multiple cylinder bodies during heating, and is only suitable for single cylinder body situation. Moreover, the first stage heating temperature has exceeded the liquidus temperature of copper alloy, and the temperature difference between different cylinder bodies cannot be optimized.

[0005] CN 116124820A discloses a copper-steel bimetal casting experiment method, which comprises: placing a copper-lead alloy test block in an alloy steel crucible, and then using a high-temperature confocal laser microscope to perform a casting experiment on the copper-lead alloy test block. The casting experiment comprises a first heating stage, a second heating stage and a solidification stage in sequence. The end point temperature of the first heating stage is 1060-1100℃, the holding temperature of the second heating stage is 1000℃, and the average cooling rate of the solidification stage is above 30℃ / s. In this method, the temperature of the first stage of the casting experiment is still above the liquidus temperature of the copper-lead alloy, and it is also not suitable for the case of simultaneous processing of multiple cylinder bodies, and it does not consider how to control when there is a temperature difference between different cylinder bodies.

[0006] In summary, for the quality consistency control of multiple copper-steel bimetal cylinder body casting processing, the temperature of different stages during heating needs to be adjusted according to the distribution of temperature difference between different cylinder bodies, to reduce the temperature difference between different cylinder bodies and avoid the difference in microstructure between different cylinder bodies, and to improve the uniformity of the casting quality between cylinder bodies. SUMMARY

[0007] In view of the problems existing in the prior art, the purpose of the present application is to provide a casting method for improving the quality consistency of copper-steel bimetal cylinder body, which divides the heating stage during simultaneous casting processing of multiple cylinder bodies, especially controls the temperature of the first stage heating below the liquidus temperature of copper alloy, reduces the liquid state time and the time difference of reaching uniform temperature between the inner and outer cylinder bodies, improves the consistency and uniformity of the casting quality between cylinder bodies, and improves the pass rate of the casting product.

[0008] To achieve the above object, the present application adopts the following technical scheme:

[0009] The present application provides a melting casting method for improving the consistency of copper-steel bimetal cylinder quality, which comprises the following steps:

[0010] (1) Put several groups of steel matrix and copper alloy into the melting casting equipment uniformly, set the heating program to heat and melt, and end the heat preservation; the heating program comprises two-stage heating and heat preservation, and the terminal temperature of the first-stage heating is 810-880℃, for example, 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃ or 880℃, but is not limited to the listed values, and other values not listed in the range are also applicable;

[0011] (2) After the heat preservation in step (1) is ended, cooling is performed to obtain a copper-steel bimetal cylinder.

[0012] In the present application, for the melting casting of the copper-steel bimetal cylinder, when multiple cylinders are processed in the same batch, according to the different placement positions, the cylinders can be divided into inner layer and outer layer cylinders, and because the heating of the inner and outer layer cylinders has a sequence, the present application controls the heating process to reduce the temperature difference between different cylinders, the present application divides the heating and melting process into two-stage heating and heat preservation, controls the terminal temperature of the first-stage heating below the liquidus temperature of the copper alloy, performs heat preservation before the copper alloy is completely melted, greatly reduces the difference in liquid time between the inner and outer layer cylinders, avoids the difference in matrix structure caused by the different liquid times, and then performs the second-stage heating and heat preservation, so that different cylinders are at the same temperature starting point, reduces the difference in cylinder temperature equalization time in the subsequent heating process, effectively improves the uniformity of the melting casting quality between the cylinders, and improves the qualified rate of cylinder product processing; the method is simple to operate, reasonable in design, high in production efficiency, low in production cost, and wide in application range.

[0013] The following is a preferred technical scheme of the present application, but is not a limitation of the technical scheme provided by the present application, and through the following technical scheme, the technical purpose and beneficial effects of the present application can be better achieved and realized.

[0014] As a preferred technical scheme of the present application, the material of the steel matrix in step (1) is alloy steel, including chromium-molybdenum steel or chromium steel.

[0015] Preferably, the chromium-molybdenum steel includes 42CrMoS4, and the chromium steel includes 40Cr or 42Cr.

[0016] In the present application, according to the selection of the steel matrix material, the austenitizing temperature is above 880℃, so the first-stage heating and heat preservation will not cause the phase change of the copper matrix material of the cylinder, thereby not causing the difference in structure.

[0017] As a preferred technical solution of the present application, the copper alloy in step (1) comprises any one of tin-lead bronze, aluminum bronze, tin bronze or bismuth bronze or a combination of at least two thereof, and typical but non-limiting examples of the combination include: a combination of tin-lead bronze and aluminum bronze, a combination of aluminum bronze and tin bronze, a combination of tin-lead bronze, aluminum bronze and tin bronze, a combination of aluminum bronze, tin bronze and bismuth bronze, etc.

[0018] Preferably, the tin-lead bronze comprises CuSn10Pb10 or CuSn7Pb15.

[0019] In the present application, the copper alloy used for casting the cylinder body is generally a tin-lead alloy of copper, and the solidus and liquidus temperatures thereof gradually decrease with the increase of the tin-lead alloy content, and the solid-liquid phase temperature range is relatively wide. For example, the solidus temperature of CuSn10Pb10 is 790°C, and the liquidus temperature is 880°C. Therefore, when casting using a box furnace, it is not necessary to use a too high casting temperature, otherwise it will only increase the time for uniform temperature between the cylinder bodies, and seriously it will cause the grain coarsening and abnormal growth of the outer cylinder body steel.

[0020] Preferably, the copper alloy is placed in the molten pool groove of the steel base body to form a group of cylinder bodies to be processed.

[0021] As a preferred technical solution of the present application, the steel base body and the copper alloy are cleaned and dried before being placed into the casting equipment.

[0022] Preferably, the cleaning is performed in a cleaning machine.

[0023] Preferably, the temperature of the cleaning is 50-70°C, such as 50°C, 52°C, 55°C, 58°C, 60°C, 62°C, 65°C, 68°C or 70°C, etc., but not limited to the listed values, and other values not listed in this value range are also applicable; and the time is 20-30 min, such as 20 min, 22 min, 24 min, 25 min, 27 min, 28 min or 30 min, etc., but not limited to the listed values, and other values not listed in this value range are also applicable.

[0024] Preferably, the temperature of the drying is 60-80°C, such as 60°C, 62°C, 65°C, 68°C, 70°C, 72°C, 75°C, 78°C or 80°C, etc., but not limited to the listed values, and other values not listed in this value range are also applicable; and the time is 10-20 min, such as 10 min, 12 min, 14 min, 15 min, 16 min, 18 min or 20 min, etc., but not limited to the listed values, and other values not listed in this value range are also applicable.

[0025] In the present application, the drying time is short, at this time the purging drying method can be used to improve the drying rate.

[0026] As a preferred technical solution of the present application, the melting equipment in step (1) comprises a box furnace, and a plurality of groups of steel substrates and copper alloys are placed on tool racks in the box furnace.

[0027] Preferably, the steel substrates are uniformly placed on the tool racks in a horizontal and vertical array manner, and under the condition that the size of the box furnace is constant, the number of the steel substrates varies according to the size of the steel substrates.

[0028] Preferably, the distance between adjacent steel substrates is 0.5-2 cm, for example, 0.5 cm, 0.8 cm, 1 cm, 1.2 cm, 1.5 cm, 1.8 cm or 2 cm, but not limited to the listed values, other values not listed in this range are also applicable.

[0029] As a preferred technical solution of the present application, the holding time after the first stage heating in step (1) is 50-70 min, for example, 50 min, 52 min, 55 min, 58 min, 60 min, 62 min, 65 min, 68 min or 70 min, but not limited to the listed values, other values not listed in this range are also applicable.

[0030] In the present application, the copper alloy is held after the first stage heating, and the temperature is in the solid-liquid phase line temperature interval, the cylinder body is uniformly treated in this interval, the copper block partially melts and is in a semi-solid state, has high viscosity and poor flowability, and will not fill the molten copper pool in the steel substrate, ensuring that there is no difference in liquid time at this time.

[0031] Preferably, the heating rate of the first stage heating is 30-50℃ / min, for example, 30℃ / min, 32℃ / min, 35℃ / min, 38℃ / min, 40℃ / min, 42℃ / min, 45℃ / min, 48℃ / min or 50℃ / min, but not limited to the listed values, other values not listed in this range are also applicable.

[0032] In the present application, during the first stage heating process, when the copper alloy is heated to above the solidus temperature, local melting begins, and a peritectic reaction occurs at the same time, the Pb phase produces a single liquid phase with the surrounding copper liquid, and during the subsequent holding process, the liquid phase volume fraction of the copper block gradually increases, and the peritectic reaction continues, and Pb dissolves in the surrounding liquid copper; on the other hand, the initial structure of the steel substrate partially transforms into austenite.

[0033] Preferably, a protective gas is introduced during the heating and melting process in step (1) to maintain an oxidation-free atmosphere.

[0034] In the present application, in order to avoid the reaction between oxygen and other components and metal components during the casting of the cylinder body, the box furnace needs to be vacuumized and filled with protective gas before heating and casting, the protective gas can be selected from nitrogen, inert gas and the like, and an oxidation-free atmosphere is maintained during the heating and casting process to avoid the oxidation of the copper layer and the steel substrate.

[0035] As a preferred technical solution of the present application, the terminal temperature of the second stage heating is 1020-1040℃, such as 1020℃, 1022℃, 1025℃, 1028℃, 1030℃, 1032℃, 1035℃, 1038℃ or 1040℃, etc., but not limited to the listed values, other values not listed in this range are also applicable.

[0036] Preferably, the heating rate of the second stage heating is 5-8℃ / min, such as 5℃ / min, 5.5℃ / min, 6℃ / min, 6.5℃ / min, 7℃ / min, 7.5℃ / min or 8℃ / min, etc., but not limited to the listed values, other values not listed in this range are also applicable.

[0037] In the present application, during the second stage heating and holding process, the copper block is further melted until complete melting, and the uniformity of the liquid components is further increased, and the steel substrate is completely austenitized.

[0038] As a preferred technical solution of the present application, the cooling in step (2) is carried out in the cooling cavity of the casting equipment, and the heated steel substrate and molten copper liquid are transferred from the casting furnace to the cooling cavity.

[0039] Preferably, the cooling in step (2) includes any one or a combination of at least two of natural cooling, gas medium cooling or liquid medium cooling, typical but non-limiting examples of the combination include: a combination of natural cooling and gas medium cooling, a combination of gas medium cooling and liquid medium cooling, a combination of natural cooling, gas medium cooling and liquid medium cooling, etc.

[0040] Preferably, the gas medium includes nitrogen and / or inert gas, and the liquid medium includes water or cooling liquid.

[0041] Preferably, the cylinder is cooled to below 150℃, for example 150℃, 145℃, 140℃, 135℃, 130℃, 125℃, 120℃, 110℃ or 100℃, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0042] In the present application, the cylinder is cooled to transform from austenite state to low-temperature stable phase structure.

[0043] As a preferred technical solution of the present application, after the cooling in step (2) is completed, the cylinder is subjected to tempering treatment.

[0044] Preferably, the tempering treatment temperature is 560-630℃, for example 560℃, 570℃, 580℃, 590℃, 600℃, 610℃, 620℃ or 630℃, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0045] Preferably, the tempering treatment holding time is 120-180min, for example 120min, 130min, 140min, 150min, 160min, 170min or 180min, etc., but not limited to the listed values, and other values not listed in the range are also applicable.

[0046] Preferably, the cooling method after the tempering treatment is air cooling to room temperature.

[0047] Preferably, the microstructure of the steel matrix after the tempering treatment is tempered sorbite.

[0048] In the present application, through cooling and tempering treatment, the microstructure of the steel matrix can be transformed into tempered sorbite, which has excellent strength and toughness, and excellent mechanical properties, which is required based on the application of the cylinder. As a key component in the plunger pump or motor, the bimetallic cylinder cooperates with the plunger and the flow distribution disc to form a sealed volume to achieve oil suction and discharge to provide power. During service, it is subjected to impact and friction, so it needs to have good strength and excellent fatigue resistance.

[0049] As a preferred technical solution of the present application, the melting and casting method comprises the following steps:

[0050] (1) A plurality of groups of steel matrix and copper alloy are uniformly placed in a melting and casting device, the material of the steel matrix includes chromium molybdenum steel or chromium steel, the copper alloy includes any one or a combination of at least two of tin-lead bronze, aluminum bronze, tin bronze or bismuth bronze, the steel matrix and the copper alloy are cleaned and dried before being placed in the melting and casting device, the cleaning temperature is 50-70 DEG C, the time is 20-30 min, the drying temperature is 60-80 DEG C, and the time is 10-20 min, the melting and casting device includes a box furnace, a plurality of groups of steel matrix and copper alloy are uniformly placed on a tooling rack in the box furnace in a horizontal and vertical array manner, the distance between adjacent steel matrix is 0.5-2 cm; a heating program is set to heat and melt, until the end of the heat preservation, the heating program includes two-stage heating and heat preservation, a protective gas is introduced during the heating and melting process to maintain an oxidation-free atmosphere, the end temperature of the first stage heating is 810-880 DEG C, the heat preservation time is 50-70 min, and the heating rate is 30-50 DEG C / min; the end temperature of the second stage heating is 1020-1040 DEG C, the heat preservation time is 30-40 min, and the heating rate is 5-8 DEG C / min;

[0051] (2) After the heat preservation in step (1) is completed, cooling is carried out, the cooling is carried out in a cooling cavity of the melting and casting device, the heated steel matrix and the molten copper liquid are collectively transferred to the cooling cavity, the cooling mode includes any one or a combination of at least two of natural cooling, gas medium cooling or liquid medium cooling, when the cylinder body is cooled to below 150 DEG C, the furnace is discharged for air cooling until it is cooled to room temperature; after the cooling is completed, the cylinder body is subjected to tempering treatment, the tempering treatment temperature is 560-630 DEG C, the heat preservation time is 120-180 min, the cooling mode after the tempering treatment is air cooling until it is cooled to room temperature, a copper-steel bimetal cylinder body is obtained, and the metallographic structure of the steel matrix after the tempering treatment is tempered sorbite.

[0052] Compared with the prior art, the present application has the following beneficial effects:

[0053] (1) In the process of simultaneously melting and casting a plurality of cylinder bodies, the present application divides the heating stage, especially controls the temperature of the first stage heating to be below the liquidus temperature of the copper alloy, and performs heat preservation before the copper alloy is completely melted, thereby greatly reducing the difference in liquid state time between the inner and outer cylinder bodies;

[0054] (2) In the process of the present application, after the first stage heating and heat preservation, the second stage heating and heat preservation are carried out, different cylinder bodies are at the same temperature starting point, the difference in cylinder body temperature uniform time in the subsequent heating process is reduced, the uniformity and consistency of the melting and casting quality between the cylinder bodies are effectively improved, the qualified rate of the cylinder body products is improved, and can be more than 98%;

[0055] (3) The method has simple operation, reasonable design, high production efficiency, low production cost, and wide application range. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 is a temperature change curve in a heating and melting casting process of the copper-steel bimetallic cylinder body provided in Embodiment 1 of the present application;

[0057] Figure 2 is a metallographic structure of the copper layer in the inner layer copper-steel bimetallic cylinder body provided in Embodiment 1 of the present application;

[0058] Figure 3 is a metallographic structure of the copper layer in the outer layer copper-steel bimetallic cylinder body provided in Embodiment 1 of the present application;

[0059] Figure 4 is a metallographic structure of the steel matrix in the inner layer copper-steel bimetallic cylinder body provided in Embodiment 1 of the present application;

[0060] Figure 5 is a metallographic structure of the steel matrix in the outer layer copper-steel bimetallic cylinder body provided in Embodiment 1 of the present application;

[0061] Figure 6 is a temperature change curve in a heating and melting casting process of the copper-steel bimetallic cylinder body provided in Comparative Example 1 of the present application;

[0062] Figure 7 is a metallographic structure of the copper layer in the inner layer copper-steel bimetallic cylinder body provided in Comparative Example 1 of the present application;

[0063] Figure 8 is a metallographic structure of the copper layer in the outer layer copper-steel bimetallic cylinder body provided in Comparative Example 1 of the present application;

[0064] Figure 9 is a metallographic structure of the steel matrix in the inner layer copper-steel bimetallic cylinder body provided in Comparative Example 1 of the present application;

[0065] Figure 10 is a metallographic structure of the steel matrix in the outer layer copper-steel bimetallic cylinder body provided in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0066] To better illustrate the present application, the technical solutions of the present application are described in detail below. However, the following examples are only simple examples of the present application, and do not represent or limit the protection scope of the present application. The protection scope of the present application is subject to the claims.

[0067] The following are typical but non-limiting examples of the present application:

[0068] Example 1:

[0069] The embodiment provides a melting and casting method for improving the quality consistency of a copper-steel bimetal cylinder, and the melting and casting method comprises the following steps:

[0070] (1) uniformly placing a plurality of groups of steel substrates and copper alloys into a melting and casting device, the steel substrate is made of chromium-molybdenum steel 42CrMoS4, the copper alloy is tin-lead bronze CuSn10Pb10, the steel substrate and the copper alloy are cleaned and dried before being placed into the melting and casting device, the cleaning temperature is 60 DEG C, and the cleaning time is 25 min, the drying temperature is 70 DEG C, and the drying time is 15 min; the melting and casting device is a box-type furnace, 16 groups of steel substrates and copper alloys are uniformly placed on a tooling frame in the box-type furnace in a horizontal and vertical array 4x4 mode, the distance between adjacent steel substrates is 1 cm; a heating program is set to heat and melt, until the end of the heat preservation, the temperature change curve in the heating and melting process is as shown in Figure 1 , argon is introduced in the heating and melting process, an oxygen-free atmosphere is maintained, the heating is divided into two-stage heating and heat preservation, the end temperature of the first-stage heating is 840 DEG C, the heat preservation time is 60 min, the temperature rising rate is 48 DEG C / min, the end temperature of the second-stage heating is 1038 DEG C, the heat preservation time is 40 min, and the temperature rising rate is 6.5 DEG C / min;

[0071] (2) after the heat preservation in step (1) is completed, cooling is performed, the cooling is performed in a cooling cavity of the melting and casting device, the heated steel substrate and the molten copper liquid are collectively transferred into the cooling cavity, the cooling mode is nitrogen blowing and cooling, when the cylinder is cooled to 150 DEG C, the cylinder is taken out of the furnace for air cooling until the cylinder is cooled to room temperature; after the cooling is completed, the cylinder is subjected to tempering treatment, the tempering treatment temperature is 600 DEG C, the heat preservation time is 120 min, the cooling mode after the tempering treatment is air cooling until the cylinder is cooled to room temperature, and a copper-steel bimetal cylinder is obtained.

[0072] The copper-steel bimetal cylinder prepared in the embodiment is observed by using an optical microscope, one cylinder is selected from the inner layer and the outer layer respectively, the metallographic structure of the copper layer in the inner layer cylinder and the outer layer cylinder is as shown in Figure 2 and 3 respectively, the metallographic structure of the steel substrate is as shown in Figure 4 and Figure 5 respectively; hardness detection is performed on the two copper-steel bimetal cylinders, the hardness detection is performed by using a Brinell hardness tester, and the detection position is the surface of the copper layer.

[0073] In the embodiment, the Figure 2 and Figure 3It can be seen that the size and distribution of the Pb phase in the copper layer of the inner and outer cylinders are quite consistent. The average size of the Pb phase in the copper layer of the inner cylinder is 25 μm, and the average size of the Pb phase in the copper layer of the outer cylinder is 30 μm. The hardness of the copper layer of the inner cylinder is 100 HBW2.5 / 62.5, and the hardness of the copper layer of the outer cylinder is 101 HBW2.5 / 62.5.

[0074] Depend on Figure 4 and Figure 5 It can be seen that the metallographic structure of the steel matrix of the inner and outer cylinder bodies is tempered bainite. The hardness of the steel matrix in the inner cylinder body is 273 HBW2.5 / 187.5, and the hardness of the steel matrix in the outer cylinder body is 275 HBW2.5 / 187.5. It can be seen that the performance consistency of the inner and outer cylinder bodies processed by the same batch of casting is good.

[0075] Example 2:

[0076] This embodiment provides a casting method for improving the quality consistency of a copper-steel bimetallic cylinder, the casting method comprising the following steps:

[0077] (1) Several groups of steel substrates and copper alloys are evenly placed in a melting and casting device. The material of the steel substrate is chromium-molybdenum steel 42CrMoS4, and the copper alloy is tin-lead bronze CuSn10Pb10. The steel substrates and copper alloys are cleaned and dried before being placed in the melting and casting device. The cleaning temperature is 70°C and the time is 20 minutes. The drying temperature is 80°C and the time is 10 minutes. The melting and casting device is a box-type furnace. 16 groups of steel substrates and copper alloys are evenly placed in a 4×4 horizontal and vertical array. The steel substrates were placed on a fixture rack in a box furnace with a distance of 0.5 cm between adjacent steel substrates. A heating program was set for heating and casting until the end of the heat preservation. Argon was introduced during the heating and casting process to maintain a non-oxidizing atmosphere. The heating was divided into two stages of heating and heat preservation. The end temperature of the first stage of heating was 810°C, the heat preservation time was 70 minutes, and the heating rate was 30°C / min. The end temperature of the second stage of heating was 1030°C, the heat preservation time was 35 minutes, and the heating rate was 5°C / min.

[0078] (2) After the step (1) is completed, cooling is performed. The cooling is performed in a cooling chamber of the melting and casting equipment. The heated steel substrate and the molten copper liquid are transferred to the cooling chamber together. The cooling method is water cooling. When the cylinder body is cooled to 140°C, it is taken out of the furnace and air-cooled until it is cooled to room temperature. After the cooling is completed, the cylinder body is tempered. The tempering temperature is 560°C and the holding time is 180 minutes. The cooling method after the tempering treatment is air cooling until it is cooled to room temperature to obtain a copper-steel bimetallic cylinder body.

[0079] The copper steel bimetal cylinder prepared in the embodiment is observed by optical microscope from the inner layer and the outer layer respectively, and the hardness of the two copper steel bimetal cylinders is detected, and the detection conditions are the same as those in embodiment 1.

[0080] In the embodiment, the size and distribution of Pb phase in the copper layer of the inner layer and the outer layer cylinder are good in consistency, the average size of Pb phase in the copper layer of the inner layer cylinder is 27 μm, and the average size of Pb phase in the copper layer of the outer layer cylinder is 29 μm; the hardness of the copper layer of the inner layer cylinder is 108 HBW2.5 / 62.5, and the hardness of the copper layer of the outer layer cylinder is 110 HBW2.5 / 62.5.

[0081] The metallographic structure of the steel matrix of the inner layer and the outer layer cylinder is tempered sorbite, the hardness of the steel matrix of the inner layer cylinder is 282 HBW2.5 / 187.5, and the hardness of the steel matrix of the outer layer cylinder is 285 HBW2.5 / 187.5; it can be seen that the performance consistency of the inner layer and the outer layer cylinder processed by melting and casting in the same batch is good.

[0082] Embodiment 3:

[0083] The embodiment provides a melting and casting method for improving the quality consistency of a copper steel bimetal cylinder, and the melting and casting method comprises the following steps:

[0084] (1) Put a plurality of groups of steel matrix and copper alloy into a melting and casting equipment uniformly, the material of the steel matrix is chromium steel 42Cr, the copper alloy is tin-lead bronze CuSn10Pb10, the steel matrix and the copper alloy are cleaned and dried before being put into the melting and casting equipment, the cleaning temperature is 50°C, and the cleaning time is 30 min, the drying temperature is 60°C, and the drying time is 20 min; the melting and casting equipment is a box-type furnace, 16 groups of steel matrix and copper alloy are uniformly placed on a tooling rack in the box-type furnace in a horizontal and vertical array 4×4 mode, the distance between adjacent steel matrix is 1.5 cm; set a heating program to heat and melt, until the end of the heat preservation, nitrogen is introduced during the heating and melting process to maintain an oxidation-free atmosphere, the heating is divided into two stages of heating and heat preservation, the end point temperature of the first stage of heating is 875°C, the heat preservation time is 50 min, and the heating rate is 40°C / min, the end point temperature of the second stage of heating is 1020°C, the heat preservation time is 30 min, and the heating rate is 8°C / min;

[0085] (2) After the cooling of step (1) is completed, the cooling is performed in a cooling chamber of a melting and casting device, the heated steel matrix and the molten copper liquid are transferred into the cooling chamber together, the cooling is performed in the following manner: first nitrogen blowing cooling, then natural cooling, when the cylinder body is cooled to 130℃, the cylinder body is taken out of the furnace for air cooling until it is cooled to room temperature; after the cooling is completed, the cylinder body is subjected to tempering treatment, the tempering treatment is performed at a temperature of 630℃ for 135min, the cooling after the tempering treatment is air cooling until it is cooled to room temperature, thereby obtaining a copper-steel bimetal cylinder body.

[0086] In the copper-steel bimetal cylinder body prepared in this example, one cylinder body is selected from the inner layer and the outer layer respectively, and is observed by using an optical microscope, and hardness detection is performed on the two copper-steel bimetal cylinder bodies, and the detection conditions are the same as in Example 1.

[0087] In this example, the size and distribution of the Pb phase in the copper layer of the inner layer and the outer layer cylinder body are both good in consistency, the average size of the Pb phase in the copper layer of the inner layer cylinder body is 33μm, and the average size of the Pb phase in the copper layer of the outer layer cylinder body is 35μm; the hardness of the copper layer of the inner layer cylinder body is 96 HBW2.5 / 62.5, and the hardness of the copper layer of the outer layer cylinder body is 98 HBW2.5 / 62.5.

[0088] The metallographic structure of the steel matrix of the inner layer and the outer layer cylinder body is both tempered sorbite, the hardness of the steel matrix of the inner layer cylinder body is 284 HBW2.5 / 187.5, and the hardness of the steel matrix of the outer layer cylinder body is 288 HBW2.5 / 187.5; it can be seen that the performance consistency of the inner layer and the outer layer cylinder bodies processed by the same batch of melting and casting is good.

[0089] Example 4:

[0090] The present example provides a melting and casting method for improving the quality consistency of a copper-steel bimetal cylinder body, the melting and casting method comprises the following steps:

[0091] (1) Put several groups of steel matrix and copper alloy into the melting equipment uniformly, the material of the steel matrix is chromium steel 40Cr, the copper alloy is tin-lead bronze CuSn7Pb15, the steel matrix and the copper alloy are cleaned and dried before being put into the melting equipment, the cleaning temperature is 65℃, the time is 22 min, the drying temperature is 75℃, the time is 12 min; the melting equipment is a box furnace, 25 groups of steel matrix and copper alloy are uniformly placed on the tooling frame in the box furnace in the manner of horizontal and vertical array 5x5, the distance between adjacent steel matrixes is 2 cm; set the heating program to heat and melt, until the end of the holding, helium is introduced during the heating and melting to maintain the non-oxidizing atmosphere, the heating is divided into two stages of heating and holding, the end temperature of the first stage of heating is 825℃, the holding time is 55 min, the heating rate is 35℃ / min, the end temperature of the second stage of heating is 1025℃, the holding time is 32 min, the heating rate is 7℃ / min;

[0092] (2) After the holding in step (1) is completed, cooling is performed, the cooling is performed in the cooling cavity of the melting equipment, the heated steel matrix and the molten copper liquid are transferred into the cooling cavity together, the cooling manner is water cooling first, and then natural cooling, when the cylinder body is cooled to 120℃, the furnace is discharged for air cooling until it is cooled to room temperature; after the cooling is completed, the cylinder body is subjected to tempering treatment, the tempering treatment temperature is 580℃, the holding time is 160 min, the cooling manner after the tempering treatment is air cooling until it is cooled to room temperature, and a copper-steel bimetal cylinder body is obtained.

[0093] The copper-steel bimetal cylinder bodies prepared in this example are observed by an optical microscope, and the hardness of the two copper-steel bimetal cylinder bodies is detected, and the detection conditions are the same as in example 1.

[0094] In this example, the size and distribution of the Pb phase in the copper layer of the inner layer and outer layer cylinder bodies are both good consistency, the average size of the Pb phase in the copper layer of the inner layer cylinder body is 33 μm, and the average size of the Pb phase in the copper layer of the outer layer cylinder body is 35 μm; the hardness of the copper layer of the inner layer cylinder body is 96 HBW2.5 / 62.5, and the hardness of the copper layer of the outer layer cylinder body is 98 HBW2.5 / 62.5;

[0095] The metallographic structure of the steel matrix of the inner layer and outer layer cylinder bodies is both tempered sorbite, the hardness of the steel matrix of the inner layer cylinder body is 265 HBW2.5 / 187.5, and the hardness of the steel matrix of the outer layer cylinder body is 270 HBW2.5 / 187.5; it can be known that the performance consistency of the inner layer and outer layer cylinder bodies processed by the same batch of melting is good.

[0096] Example 5:

[0097] The embodiment provides a melting and casting method for improving the quality consistency of a copper-steel bimetal cylinder, and the melting and casting method comprises the following steps:

[0098] (1) uniformly placing a plurality of groups of steel substrates and copper alloys into a melting and casting device, the steel substrate is made of chromium-molybdenum alloy steel 42CrMoS4, the copper alloy is tin-lead bronze CuSn7Pb15, the steel substrate and the copper alloy are cleaned and dried before being placed into the melting and casting device, the cleaning temperature is 55 DEG C, and the cleaning time is 27 min, the drying temperature is 65 DEG C, and the drying time is 18 min; the melting and casting device is a box-type furnace, 25 groups of steel substrates and copper alloys are uniformly placed on a tooling frame in the box-type furnace in a horizontal and vertical array 5x5 mode, the distance between adjacent steel substrates is 1.2 cm; a heating program is set to perform heating and melting and casting, until the end of the heat preservation, argon is introduced during the heating and melting and casting process to maintain an oxygen-free atmosphere, the heating is divided into two-stage heating and heat preservation, the end temperature of the first-stage heating is 860 DEG C, the heat preservation time is 65 min, and the temperature rising rate is 45 DEG C / min, the end temperature of the second-stage heating is 1035 DEG C, the heat preservation time is 38 min, and the temperature rising rate is 6 DEG C / min;

[0099] (2) after the heat preservation in step (1) is completed, cooling is performed, the steel substrate and the molten copper liquid after being heated are collectively transferred into a cooling cavity of the melting and casting device, the cooling mode is argon blowing and cooling first, and then natural cooling, when the cylinder is cooled to 135 DEG C, the furnace is discharged to perform air cooling until the cylinder is cooled to room temperature; after the cooling is completed, the cylinder is subjected to tempering treatment, the tempering treatment temperature is 620 DEG C, the heat preservation time is 130 min, the cooling mode after the tempering treatment is air cooling until the cylinder is cooled to room temperature, and a copper-steel bimetal cylinder is obtained.

[0100] In the copper-steel bimetal cylinder prepared in the embodiment, one cylinder is observed by using an optical microscope from the innermost layer and the outermost layer respectively, and hardness detection is performed on the two copper-steel bimetal cylinders, and the detection conditions are the same as in the embodiment 1.

[0101] In the embodiment, the size and distribution of the Pb phase in the copper layer of the inner layer and the outer layer cylinder are good in consistency, the average size of the Pb phase in the copper layer of the inner layer cylinder is 31 μm, the average size of the Pb phase in the copper layer of the outer layer cylinder is 35 μm, the hardness of the copper layer of the inner layer cylinder is 95 HBW2.5 / 62.5, and the hardness of the copper layer of the outer layer cylinder is 97 HBW2.5 / 62.5.

[0102] The microstructure of the steel matrix of the inner layer and the outer layer cylinder is tempered sorbite, the hardness of the steel matrix of the inner layer cylinder is 280 HBW2.5 / 187.5, and the hardness of the steel matrix of the outer layer cylinder is 285 HBW2.5 / 187.5; thus, the performance consistency of the inner layer and the outer layer cylinder processed by the same batch of melting and casting is good.

[0103] Comparative Example 1

[0104] The present comparative example provides a melting and casting method of a copper-steel bimetal cylinder, which refers to the method in Example 1, and the difference is that the heating in step (1) is not divided into two stages, but is heated to 1038℃ at one time, and the temperature change curve in the heating and casting process is as shown in Figure 6 , and the holding time is the sum of the two-stage holding time.

[0105] In the copper-steel bimetal cylinder prepared in the present comparative example, one cylinder is selected from the inner layer and the outer layer respectively for observation by an optical microscope, and the microstructure of the copper layer in the inner layer cylinder and the outer layer cylinder is respectively as shown in Figure 7 and 8 , and the microstructure of the steel matrix is respectively as shown in Figure 9 and Figure 10 ; and the hardness of the two copper-steel bimetal cylinders is detected, and the detection conditions are the same as in Example 1.

[0106] In the present comparative example, it can be known from Figure 7 and Figure 8 that there is an obvious difference in the size and distribution of the Pb phase in the copper layer of the inner layer and the outer layer cylinder, the average size of the Pb phase in the copper layer of the inner layer cylinder is 88μm, and the average size of the Pb phase in the copper layer of the outer layer cylinder is 45μm; the hardness of the copper layer of the inner layer cylinder is 89 HBW2.5 / 62.5, and the hardness of the copper layer of the outer layer cylinder is 98 HBW2.5 / 62.5;

[0107] It can be known from Figure 9 and Figure 10 that the microstructure of the steel matrix of the inner layer and the outer layer cylinder is tempered sorbite, the hardness of the steel matrix of the inner layer cylinder is 253 HBW2.5 / 187.5, and the hardness of the steel matrix of the outer layer cylinder is 278 HBW2.5 / 187.5; thus, the performance of the inner layer and the outer layer cylinder processed by the same batch of melting and casting is different, and the consistency is poor.

[0108] From the above examples and comparative examples, it can be seen that in the process of simultaneously casting multiple cylinder bodies, by dividing the heating stage, especially by controlling the temperature of the first stage heating to be below the liquidus temperature of the copper alloy and by keeping the copper alloy at temperature before it is completely melted, the difference in liquid time between the inner and outer cylinder bodies is greatly reduced; when the process is followed by the first stage heating and keeping at temperature and then the second stage heating and keeping at temperature, the different cylinder bodies are again at the same temperature starting point, the difference in cylinder body temperature equalization time in the subsequent heating process is reduced, the uniformity and consistency of the casting quality between the cylinder bodies is effectively improved, the qualified rate of the cylinder body products is improved to more than 98%; the process is simple to operate, the design is reasonable, the production efficiency is high, the production cost is low, and the application range is wide.

[0109] The applicant declares that the detailed method of the present application is illustrated by the above examples, but the present application is not limited to the above detailed method, i.e. it does not mean that the present application must rely on the above detailed method to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the method of the present application and addition of auxiliary steps, selection of specific modes, etc. all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method of improving the quality consistency of a copper-steel bimetallic cylinder by casting, characterized by, The casting method comprises the following steps: (1) Put several groups of steel matrix and copper alloy into the casting equipment uniformly, set the heating program to heat and cast, and end the heat preservation; the heating program comprises two-stage heating and heat preservation, the end temperature of the first-stage heating is 810-880℃, and the end temperature of the first-stage heating is within the solid-liquid phase line temperature range of the copper alloy; (2) After the heat preservation in step (1) is ended, cooling is performed to obtain a copper-steel bimetallic cylinder body; The copper alloy is tin-lead bronze, and the tin-lead bronze comprises CuSn10Pb10 or CuSn7Pb15; After the cooling in step (2) is ended, the cylinder body is subjected to tempering treatment, the temperature of the tempering treatment is 560-630℃, and the heat preservation time is 120-180min.

2. The casting method according to claim 1, characterized in that, The steel matrix in step (1) is made of alloy steel, including chromium-molybdenum steel or chromium steel; The chromium-molybdenum steel comprises 42CrMoS4, and the chromium steel comprises 40Cr or 42Cr.

3. The casting method according to claim 1, characterized by, The copper alloy is put into the molten pool groove of the steel matrix to form a group of cylinder bodies to be processed.

4. The casting method according to claim 1, characterized by, Before the steel matrix and the copper alloy in step (1) are put into the casting equipment, cleaning and drying are performed; The cleaning is performed in a cleaning machine; The temperature of the cleaning is 50-70℃, and the time is 20-30min; The temperature of the drying is 60-80℃, and the time is 10-20min.

5. The casting method according to claim 1, characterized by, The casting equipment in step (1) comprises a box-type furnace, and the several groups of steel matrix and copper alloy are placed on tooling racks in the box-type furnace; The steel matrix is placed on the tooling racks in a horizontal and vertical array manner; The distance between adjacent steel matrixes is 0.5-2cm.

6. The casting method according to claim 1, characterized by The heat preservation time after the first-stage heating in step (1) is 50-70min; The heating rate of the first-stage heating is 30-50℃ / min; During the heating and casting process in step (1), a protective gas is introduced to maintain an oxidation-free atmosphere.

7. The casting method according to claim 1, characterized by, In the heating program in step (1), the end temperature of the second-stage heating is 1020-1040℃, and the heat preservation time after the second-stage heating is 30-40min; The heating rate of the second-stage heating is 5-8℃ / min.

8. The casting method according to claim 1, characterized by, The cooling in step (2) is performed in a cooling cavity of the casting equipment, and the heated steel matrix and molten copper liquid are transferred into the cooling cavity together; The cooling mode in step (2) comprises any one or a combination of at least two of natural cooling, gas medium cooling, and liquid medium cooling; When the cylinder body is cooled to below 150℃, air cooling is performed to cool to room temperature.

9. The casting method according to claim 1, characterized by, The cooling mode after the tempering treatment is air cooling to room temperature; The metallographic structure of the steel matrix after the tempering treatment is tempered sorbite.

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