Method and device for pressure centrifugal casting of copper alloy cast ring

Abstract

The invention relates to a method and device for pressure centrifugal casting of a copper alloy cast ring, and belongs to the technical field of metal centrifugal casting. The method for pressure centrifugal casting of the copper alloy cast ring comprises the following steps that S1, pressure reduction smelting is conducted, specifically, a packaged vacuum smelting chamber is subjected to air exhaust and pressure reduction to be in a pressure vacuum state, and a mother alloy cast ingot is molten in the pressure vacuum state to form a melt; s2, centrifugal casting is conducted, specifically, the melt flows into a centrifugal casting mold of a vacuum centrifugal casting chamber, and the melt rotates under the centrifugal effect; and S3, pressurizing and solidifying: after the overflowing of the melt is completed, keeping rotation, opening an air charging device to introduce protective gas into the heat preserving furnace for pressurizing, and keeping the air pressure constant until the melt is completely solidified. According to the method for casting the copper alloy cast ring, composition segregation and the percentage of defective parts are reduced to a large extent, the turning amount is greatly reduced, the comprehensive yield and the production efficiency of the copper alloy are improved, meanwhile, material loss is reduced, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to a method and a device for pressure centrifugal casting of a copper alloy casting ring, belonging to the technical field of metal centrifugal casting. Background Art

[0002] Centrifugal casting is a casting method that uses the centrifugal force generated by the rotation of the mold to fill the mold with molten metal. This casting method is generally used to produce rotary parts such as bushings, seamless pipes, cylinders, etc. Centrifugal casting is an ideal process for producing dense copper and aluminum alloy ingots, and can be used as an effective means to improve the structure and mechanical properties of copper and aluminum alloy ingots.

[0003] At present, there are still some problems in the production of copper alloys using centrifugal casting technology. Since the alloy forming is affected by centrifugal force, the centrifugal force on the inner side of the alloy casting is small during the casting process, and the density of the inner side of the casting is poor, and even cracks, pores and other defects occur. The defective part cannot be directly used for subsequent forming processing, so it is necessary to take a large amount of turning processing to completely eliminate the defective part, which seriously affects the material utilization rate and increases the production cost.

[0004] The Chinese invention patent with application number CN202111455154.6 generates a composite magnetic field through the interaction between the induction coil device and the static magnetic field to generate a reciprocating oscillating force in the entire melt, thereby making the alloy structure more uniform and denser. However, the above method is complicated to operate, difficult to achieve precise control, and has a high cost. Summary of the invention

[0005] In order to improve the product utilization rate of copper alloy centrifugal casting, reduce the proportion of defective parts such as shrinkage and pores generated on the inner side of the casting, and avoid oxidation, air absorption and other problems caused by the atmospheric environment, the present invention provides a method and device for pressure centrifugal casting of copper alloy rings to solve the technical problems existing in the prior art as mentioned above.

[0006] The technical solution provided by the present invention is as follows:

[0007] One of the purposes of the present invention is to provide a method for pressure centrifugal casting of copper alloy casting rings, comprising the following steps:

[0008] S1: Vacuum smelting

[0009] The packaged vacuum melting chamber is evacuated and decompressed to a vacuum state, and the master alloy ingot is melted to form a melt in the vacuum state;

[0010] S2: Centrifugal Casting

[0011] The melt flows into a centrifugal casting mold in a vacuum centrifugal casting chamber, so that the melt rotates under the centrifugal effect;

[0012] S3: Pressurized solidification

[0013] After the melt has passed through, keep rotating, open the inflation device to introduce protective gas into the holding furnace for pressurization, and keep the gas pressure constant until the melt is completely solidified.

[0014] The effect of adopting the above technical scheme is that in the reduced pressure smelting stage, the vacuum is evacuated to a sub-vacuum state by a vacuum pump, which can reduce the gas element content in the melt during the melting process; in the pressurized solidification stage, the protective gas is filled to increase the pressure, which can reduce defects such as looseness and shrinkage holes in the casting ring.

[0015] On the basis of the above technical solution, the present invention can also be improved as follows:

[0016] Furthermore, in step S1, the packaging step of the vacuum melting chamber is: first preheating the crucible to 400-900°C, fixing the holding furnace on the turntable of the centrifugal casting equipment, placing the pretreated master alloy ingot into the crucible, covering the casting chamber cover of the centrifugal casting equipment, and packaging it into a centrifugal casting chamber.

[0017] Furthermore, the specific steps of centrifugal casting in step S2 are: heating the melt to a temperature 50 to 200°C higher than the liquidus temperature of the master alloy, opening the vacuum valve between the vacuum melting chamber and the centrifugal casting chamber, tilting the crucible, pouring the melt into the chute, and entering the rotating centrifugal casting mold through the chute, so that the melt rotates under the centrifugal action.

[0018] Furthermore, the rotation speed of the turntable and the holding furnace of the centrifugal casting equipment is 140-200r / min.

[0019] Furthermore, in step S1, the vacuum degree of the compressed vacuum state is 50-200Pa.

[0020] The effect of adopting the above further scheme is that under sub-vacuum conditions with a vacuum degree of 50 to 200 Pa, the dynamic properties of gas molecules are obvious and the convection phenomenon of the gas disappears. At this time, heating the metal can avoid the chemical reaction between the metal and the gas and avoid defects such as gas absorption.

[0021] Furthermore, in step S3, protective gas is introduced and pressurized to 0.2-1.0 MPa.

[0022] The effect of adopting the above further scheme is that the boosting pressure is lower than 0.2MPa. If the pressure is too low, the expected boosting effect cannot be achieved. If the pressure is greater than 1.0MPa, it will cause defects such as sand sticking, sand swelling and component segregation in the casting ring.

[0023] Furthermore, the method further comprises step S4 of decompressing, cooling and demoulding: after the melt is completely solidified, the pressure is reduced to atmospheric pressure, the casting is cooled and then demoulded to obtain a copper alloy cast ring.

[0024] The second object of the present invention is to provide a device for pressure centrifugal casting of copper alloy casting rings, comprising a vacuum melting chamber, an inflation system, and a centrifugal casting chamber; the vacuum melting chamber and the centrifugal casting chamber are connected by a chute, a centrifugal casting equipment is provided in the centrifugal casting chamber, a heat preservation furnace is provided on the centrifugal casting equipment, and the inflation system is connected to the upper end of the heat preservation furnace.

[0025] Furthermore, a crucible is provided in the vacuum melting chamber, and the crucible is used to melt the master alloy ingot; the centrifugal casting equipment includes a turntable, a centrifugal casting mold and a centrifugal shaft, and the insulation furnace is arranged on the turntable.

[0026] Furthermore, the chute is provided with a vacuum valve, the inflation system is provided with a pressure-limiting valve, and the centrifugal shaft is driven by a motor.

[0027] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0028] 1. The method for pressure centrifugal casting of copper alloy casting rings of the present invention adopts a variable pressure vacuum centrifugal casting process to prepare copper alloy casting rings, and melts under sub-vacuum conditions, thereby ensuring the accuracy and stability of the alloy composition and having a good degassing effect; during centrifugal casting, the pressure is increased, and the molten metal solidifies and forms under the dual effects of centrifugal force and gas pressure, which can greatly reduce the percentage of component segregation and defective parts, greatly reduce the amount of turning processing, improve the comprehensive yield rate and production efficiency of the copper alloy, and at the same time reduce material loss and reduce production costs.

[0029] 2. In the device for pressure centrifugal casting of copper alloy casting rings of the present invention, the inflation port of the inflation system is arranged at the upper end of the insulation furnace, and the protective gas can be filled into the centrifugal casting mold to increase the pressure on the inner outer wall of the casting ring. Combined with the effect of centrifugal force, the loose layer is closer to the inner wall of the inner side of the casting ring. The loose layer is the organization of defects caused in the centrifugal casting process. The thinner the loose layer, the larger the proportion of the effective and qualified ring body, which makes it closer to the inner wall of the inner side of the casting ring, facilitates chip removal, reduces consumption, and can effectively avoid defects such as shrinkage in the casting ring and increase the effective wall thickness.

[0030] 3. The casting method and device adopted by the present invention are reasonable and effective, and have the advantages of high yield rate, high production efficiency, low production cost and high performance of manufactured products. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the device for pressure centrifugal casting of copper alloy casting rings of the present invention;

[0032] Figure 2It is a schematic structural diagram of the centrifugal casting chamber and the inflation system of the present invention.

[0033] In the figure, 1. crucible; 2. vacuum valve; 3. chute; 4. vacuum melting chamber; 5. charging system; 6. holding furnace; 7. centrifugal casting mold; 8. turntable; 9. centrifugal shaft; 10. pressure limiting valve; 11. centrifugal casting chamber. DETAILED DESCRIPTION

[0034] The principles and features of the present invention are described below in conjunction with examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention.

[0035] The pretreatment in the specific implementation means determining the proportion of the master alloy according to the alloy composition requirements, cleaning the surface, and ensuring that the master alloy is clean and free of debris.

[0036] Example 1

[0037] A method for pressure centrifugal casting of a copper alloy casting ring comprises the following steps:

[0038] S1: Vacuum smelting

[0039] First, the crucible 1 is preheated to 600° C., the holding furnace 6 is fixed on the turntable 8 of the centrifugal casting equipment, the rotation speed of the turntable and the holding furnace of the centrifugal casting equipment is 180 r / min, the pretreated master alloy ingot is placed in the crucible 1, the casting chamber upper cover of the centrifugal casting equipment is covered, and the centrifugal casting chamber 11 is encapsulated, and the encapsulated vacuum melting chamber 4 is evacuated and decompressed to a vacuum state, so that the vacuum degree reaches 100 Pa, and the master alloy ingot is melted to form a melt;

[0040] S2: Centrifugal Casting

[0041] The melt is heated to a temperature higher than the liquidus temperature of the master alloy by 160°C, the vacuum valve 2 between the vacuum melting chamber 4 and the centrifugal casting chamber 11 is opened, the crucible 1 is tilted, the melt is poured into the chute 3, and then enters the centrifugal casting mold 7 of the centrifugal casting chamber 11 through the chute 3, so that the melt rotates under the centrifugal action;

[0042] S3: Pressurized solidification

[0043] After the melt has passed through, the rotation is maintained, and the gas charging system 5 is opened to introduce argon gas into the holding furnace 6, and the pressure is slowly increased to 0.7 MPa, and the pressure is maintained until the melt is completely solidified;

[0044] S4: Decompression cooling and demoulding

[0045] After the melt is completely solidified, the pressure is reduced to atmospheric pressure, and the casting is cooled and then demolded to obtain a copper alloy cast ring.

[0046] According to the YS / T 585-2013 ultrasonic flaw detection method for copper and copper alloy plates, the 6000Kg CuCrZr alloy casting ring cast in Example 1 has an inner diameter of 1600mm, a depth of the inner layer defect area of ​​40-50mm, good inner and outer surface conditions, and stable alloy composition.

[0047] Example 2

[0048] A method for pressure centrifugal casting of a copper alloy casting ring comprises the following steps:

[0049] S1: Vacuum smelting

[0050] First, the crucible 1 is preheated to 900° C., the holding furnace 6 is fixed on the turntable 8 of the centrifugal casting equipment, the rotation speed of the turntable and the holding furnace of the centrifugal casting equipment is 140 r / min, the pretreated master alloy ingot is placed in the crucible 1, the casting chamber upper cover of the centrifugal casting equipment is covered, and the centrifugal casting chamber 11 is encapsulated, and the encapsulated vacuum melting chamber 4 is evacuated and decompressed to a vacuum state, so that the vacuum degree reaches 50 Pa, and the master alloy ingot is melted to form a melt;

[0051] S2: Centrifugal Casting

[0052] The melt is heated to a temperature 200°C higher than the liquidus temperature of the master alloy, the vacuum valve 2 between the vacuum melting chamber 4 and the centrifugal casting chamber 11 is opened, the crucible 1 is tilted, the melt is poured into the chute 3, and then enters the centrifugal casting mold 7 of the centrifugal casting chamber 11 through the chute 3, so that the melt rotates under the centrifugal action;

[0053] S3: Pressurized solidification

[0054] After the melt has passed through, the rotation is maintained, and the gas charging system 5 is opened to introduce argon gas into the holding furnace 6, and the pressure is slowly increased to 0.2 MPa, and the pressure is maintained until the melt is completely solidified;

[0055] S4: Decompression cooling and demoulding

[0056] After the melt is completely solidified, the pressure is reduced to atmospheric pressure, and the casting is cooled and then demolded to obtain a copper alloy cast ring.

[0057] According to the YS / T 585-2013 ultrasonic flaw detection method for copper and copper alloy plates, the 6000 kg CuCrZr alloy casting ring cast in Example 2 has an inner diameter of 1600 mm, an inner layer defect area depth of 55-65 mm, inner and outer surfaces are in good condition, and the alloy composition is stable.

[0058] Example 3

[0059] A method for pressure centrifugal casting of a copper alloy casting ring comprises the following steps:

[0060] S1: Vacuum smelting

[0061] First, the crucible 1 is preheated to 400° C., the holding furnace 6 is fixed on the turntable 8 of the centrifugal casting equipment, the rotation speed of the turntable and the holding furnace of the centrifugal casting equipment is 200 r / min, the pretreated master alloy ingot is placed in the crucible 1, the casting chamber upper cover of the centrifugal casting equipment is covered, and the centrifugal casting chamber 11 is encapsulated, and the encapsulated vacuum melting chamber 4 is evacuated and decompressed to a vacuum state, so that the vacuum degree reaches 200 Pa, and the master alloy ingot is melted to form a melt;

[0062] S2: Centrifugal Casting

[0063] The melt is heated to a temperature 50°C higher than the liquidus temperature of the master alloy, the vacuum valve 2 between the vacuum melting chamber 4 and the centrifugal casting chamber 11 is opened, the crucible 1 is tilted, the melt is poured into the chute 3, and then enters the centrifugal casting mold 7 of the centrifugal casting chamber 11 through the chute 3, so that the melt rotates under the centrifugal action;

[0064] S3: Pressurized solidification

[0065] After the melt has passed through, the rotation is maintained, and the gas charging system 5 is opened to introduce argon gas into the holding furnace 6, and the pressure is slowly increased to 1.0 MPa, and the pressure is maintained until the melt is completely solidified;

[0066] S4: Decompression cooling and demoulding

[0067] After the melt is completely solidified, the pressure is reduced to atmospheric pressure, and the casting is cooled and then demolded to obtain a copper alloy cast ring.

[0068] According to the YS / T 585-2013 ultrasonic flaw detection method for copper and copper alloy plates, the 6000Kg CuCrZr alloy casting ring cast in Example 3 has an inner diameter of 1600mm, a depth of the inner layer defect area of ​​50-55mm, good inner and outer surface conditions, and stable alloy composition.

[0069] Comparative Example 1

[0070] The method for centrifugally casting a copper alloy casting ring comprises the following steps:

[0071] S1: Vacuum melting

[0072] First, the crucible 1 is preheated to 600° C., the holding furnace 6 is fixed on the turntable 8 of the centrifugal casting equipment, the rotation speed of the turntable and the holding furnace of the centrifugal casting equipment is 180 r / min, the pretreated master alloy ingot is placed in the crucible 1, the casting chamber upper cover of the centrifugal casting equipment is covered, and the centrifugal casting chamber 11 is encapsulated, and the encapsulated vacuum melting chamber 4 is evacuated and decompressed to a vacuum state, so that the vacuum degree reaches 100 Pa, and the master alloy ingot is melted to form a melt;

[0073] S2: Centrifugal Casting

[0074] The melt is heated to a temperature higher than the liquidus temperature of the master alloy by 160°C, the vacuum valve 2 between the vacuum melting chamber 4 and the centrifugal casting chamber 11 is opened, the crucible 1 is tilted, the melt is poured into the chute 3, and then enters the centrifugal casting mold 7 of the centrifugal casting chamber 11 through the chute 3, so that the melt rotates under the centrifugal action;

[0075] S3: Cooling and demoulding

[0076] After the melt is completely solidified, the vacuum is broken, the casting is cooled and then demolded to obtain a copper alloy cast ring.

[0077] Through the ultrasonic flaw detection method of copper and copper alloy plates in accordance with YS / T 585-2013, it was found that the depth of the defect shrinkage cavity on the inner side of the 6000Kg CuCrZr alloy cast ring with an inner diameter of 1600mm cast in Example 1 was about 70-80mm through turning.

[0078] In summary, the test results of Examples 1-3 and Comparative Example 1 are shown in Table 1.

[0079] Table 1 Test results of Examples 1-3 and Comparative Example 1

[0080] Different parameters Finished product wall thickness / mm Defect thickness / mm Example 1 420 40-50 Example 2 420 55-60 Example 3 420 50-55 Comparative Example 1 420 70-80

[0081] According to the data in Table 1, compared with Comparative Example 1, the defect thickness of Examples 1-3 is reduced, indicating that pressurized solidification after centrifugal casting can reduce the defective part on the inner side of the copper alloy casting ring and better ensure the yield rate of the casting ring.

[0082] like Figure 1 and Figure 2 As shown, a device for pressure centrifugal casting of copper alloy casting rings comprises a vacuum melting chamber 4, an inflation system 5, and a centrifugal casting chamber 11; the vacuum melting chamber 4 and the centrifugal casting chamber 11 are connected via a chute 3, a centrifugal casting device is arranged in the centrifugal casting chamber 11, a heat preservation furnace 6 is arranged on the centrifugal casting device, and the inflation system 5 is communicated with the upper end of the heat preservation furnace 6; a crucible 1 is arranged in the vacuum melting chamber 4, and the crucible 1 is used for melting the master alloy ingot; the centrifugal casting device comprises a turntable 8, a centrifugal casting mold 7 and a centrifugal shaft 9, and the heat preservation furnace 6 is arranged on the turntable 8; a vacuum valve 2 is arranged on the chute 3, a pressure limiting valve 10 is arranged on the inflation system 5, and the centrifugal shaft 9 is driven by a motor.

[0083] The device for pressure centrifugal casting of copper alloy casting rings of the present invention sets the inflation port of the inflation system 5 at the upper end of the insulation furnace 6, which can better inflate the centrifugal casting mold 7. Combined with the centrifugal force generated during rotation, it can effectively increase the pressure on the inner and outer walls of the casting ring, reduce defects such as shrinkage in the casting ring, improve the comprehensive yield rate and production efficiency of the copper alloy, and at the same time reduce material loss and reduce production costs.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for pressure centrifugal casting of copper alloy rings, characterized in that: The following steps are involved: S1: Vacuum smelting The packaged vacuum melting chamber is evacuated and decompressed to a vacuum state, and the master alloy ingot is melted to form a melt in the vacuum state; S2: Centrifugal Casting The melt flows into a centrifugal casting mold in a vacuum centrifugal casting chamber, so that the melt rotates under the centrifugal effect; S3: Pressurized solidification After the melt has passed through, keep rotating, open the inflation device to introduce protective gas into the holding furnace for pressurization, and keep the gas pressure constant until the melt is completely solidified.

2. The method for pressure centrifugal casting of copper alloy rings according to claim 1, characterized in that: In step S1, the packaging step of the vacuum melting chamber is: first preheat the crucible to 400-900°C, fix the holding furnace on the turntable of the centrifugal casting equipment, put the pretreated master alloy ingot into the crucible, cover the casting chamber cover of the centrifugal casting equipment, and package it into a centrifugal casting chamber.

3. The method for pressure centrifugal casting of copper alloy rings according to claim 2, characterized in that: The specific steps of step S2 centrifugal casting are: heating the melt to a temperature 50 to 200°C higher than the liquidus temperature of the master alloy, opening the vacuum valve between the vacuum melting chamber and the centrifugal casting chamber, tilting the crucible, pouring the melt into the chute, and entering the rotating centrifugal casting mold through the chute, so that the melt rotates under the centrifugal action.

4. The method for pressure centrifugal casting of copper alloy rings according to claim 3, characterized in that: The rotating speed of the turntable and the holding furnace of the centrifugal casting equipment is 140-200r / min.

5. The method for pressure centrifugal casting of copper alloy rings according to claim 1, characterized in that: In step S1, the vacuum degree of the compressed vacuum state is 50-200Pa.

6. The method for pressure centrifugal casting of copper alloy rings according to claim 1, characterized in that: In step S3, protective gas is introduced and pressurized to 0.2-1.0 MPa.

7. The method for pressure centrifugal casting of copper alloy rings according to claim 1, characterized in that: The process also includes step S4 of decompressing, cooling and demoulding: after the melt is completely solidified, the pressure is reduced to atmospheric pressure, the casting is cooled and then demoulded to obtain a copper alloy cast ring.

8. A device for pressure centrifugal casting of copper alloy rings, characterized in that: It includes a vacuum melting chamber, an inflation system, and a centrifugal casting chamber; the vacuum melting chamber and the centrifugal casting chamber are connected through a chute, the centrifugal casting chamber is provided with a centrifugal casting device, the centrifugal casting device is provided with a heat preservation furnace, and the inflation system is connected to the upper end of the heat preservation furnace.

9. The device for pressure centrifugal casting of copper alloy rings according to claim 8, characterized in that: The vacuum melting chamber is provided with a crucible, which is used for melting the master alloy ingot; the centrifugal casting equipment comprises a turntable, a centrifugal casting mold and a centrifugal shaft, and the insulation furnace is arranged on the turntable.

10. The device for pressure centrifugal casting of copper alloy rings according to claim 9, characterized in that: The chute is provided with a vacuum valve, the inflation system is provided with a pressure limiting valve, and the centrifugal shaft is driven by a motor.

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