A powder post-treatment system and method for a hot isostatic pressing jacket

Abstract

The present invention belongs to the technical field of powder metallurgy, and particularly relates to a powder post-treatment system and method for a hot isostatic pressing jacket. The system of the present invention includes a melting gas atomization device, a powder loading chamber, and a welding chamber connected in sequence. A powder conveying pipe connected to the melting gas atomization device is provided in the powder loading chamber. A vibrating table, a jacket, and a transmission mechanism provided at the bottom of the vibrating table are further provided in the powder loading chamber. The transmission mechanism connects the powder loading chamber and the welding chamber. An isolation hatch for controlling the connection or disconnection between the powder loading chamber and the welding chamber is provided between the powder loading chamber and the welding chamber. The welding chamber is connected to a vacuum system, and an induction heating device and a welding device are provided in the welding chamber. The system of the present invention integrates devices such as powder making, powder loading and compaction, degassing, and welding and encapsulation, effectively solving the problem of low production efficiency of existing jackets. At the same time, the entire system of the present invention is in a low-oxygen environment, making it possible to safely apply powders with high requirements for a low-oxygen environment, such as rare earth powders, in jacket manufacturing.

Description

Technical Field

[0001] The present invention belongs to the technical field of powder metallurgy, and particularly relates to a powder post-treatment system and method for a hot isostatic pressing jacket. Background Art

[0002] The forming processes of powder metallurgy steel include: hot isostatic pressing, cold pressing + sintering forming, and spray forming + hot extrusion, etc. The cold pressing + sintering forming method means directly applying pressure at room temperature for forming, and then sintering in a vacuum or inert gas environment, which has the advantages of low cost and simple process, but the powder is prone to oxidation, poor uniformity, and obvious elastic aftereffect; the spray forming + hot extrusion process means that the solution is atomized and then deposited on the blank when cooled to a semi-solid state, and then heated to a certain temperature for hot extrusion, which has the advantages of fine and uniform structure and low cost, etc., but due to the need for processes such as hot extrusion after spray forming, the production efficiency is low; the hot isostatic pressing method means loading the powder into a jacket (similar to the function of a mold), and then using nitrogen or argon as the pressurizing medium to directly heat and pressurize the powder for sintering forming. The hot isostatic pressing process has the advantages that the density of the prepared metal material can reach 99.99% of the theoretical density, the sintering temperature is lower than that of the conventional cold pressing - sintering process, the production efficiency is higher than that of the spray forming process + hot extrusion process, and it is easy to prepare products with high alloy content (such as high-speed steel). The vacuum jacket for hot isostatic pressing needs to have good airtightness, and the inside of the jacket must be vacuum-treated to remove the air, water vapor, and oil stains attached between the powder particles, and at the same time ensure uniform stress on the workpiece to avoid the generation of oxide films and pores due to insufficient vacuum.

[0003] The traditional powder filling process of the vacuum jacket is completed in the air through an exhaust pipe. Even if the vacuum degassing method is used, the impurities in the jacket cannot be completely removed, and after the vacuum degassing is completed, the evacuation pipe needs to be sealed and welded, resulting in low production efficiency of the jacket.

[0004] Rare earth elements are called the "vitamins" of industry. Adding a small amount of rare earth elements to high-speed steel can significantly optimize the microstructure of the steel, purify impurity elements, thereby improving the mechanical properties and corrosion resistance, and using rare earth elements La and Ce to replace V in high-speed steel can reduce the cost of high-speed steel. However, when mixing rare earth powder and high-speed steel powder in the air, the rare earth powder will oxidize and even explode. Since the traditional jacket production system fails to achieve a low-oxygen environment throughout the process, it is difficult to safely apply powders with high requirements for a low-oxygen environment, such as rare earth powder, in jacket manufacturing. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a powder post-treatment system and method for hot isostatic pressing envelopes. The powder post-treatment system of the present invention can complete a series of processes such as powder mixing, compaction, degassing, welding and encapsulation in a low-oxygen environment, improve the production efficiency and performance of the envelopes, and make it possible to apply powders with high requirements for low-oxygen environment, such as rare earth powders, in the production of envelopes.

[0006] Based on the above purposes, the technical solutions adopted by the present invention are as follows:

[0007] In the first aspect, the present invention provides a powder post-treatment system for hot isostatic pressing envelopes, including a melting gas atomization device, a powder loading chamber, and a welding chamber connected in sequence; a powder conveying pipe connected to the melting gas atomization device is provided in the powder loading chamber, and a vibrating table, an envelope, and a transmission mechanism provided at the bottom of the vibrating table are also provided in the powder loading chamber, and the transmission mechanism connects the powder loading chamber and the welding chamber; an isolation hatch for controlling whether the powder loading chamber and the welding chamber are communicated is provided between the powder loading chamber and the welding chamber; the welding chamber is connected to a vacuum system, and an induction heating device and a welding device are provided in the welding chamber.

[0008] The powder post-treatment system for hot isostatic pressing envelopes provided by the present invention integrates devices required for melting powder production, powder loading and compaction, heating and degassing, and welding and encapsulation, and effectively solves the problem of low production efficiency of existing envelopes through reasonable setting of each device; at the same time, the entire system of the present invention is in a low-oxygen environment, making it possible to safely apply powders with high requirements for low-oxygen environment, such as rare earth powders, in the manufacture of envelopes.

[0009] Preferably, the powder post-treatment system for hot isostatic pressing envelopes further includes a transition chamber communicated with the powder loading chamber, and a ball mill is also provided in the powder loading chamber.

[0010] The present invention provides a transition chamber to add rare earth powders and the like into the powder loading chamber through the transition chamber; the ball mill is arranged in the powder loading chamber to facilitate the safe mixing of rare earth powders and metal powders.

[0011] Preferably, the melting gas atomization device and the powder loading chamber are filled with a protective gas, and the protective gas is an inert gas; a cyclone classifier is also connected between the melting gas atomization device and the powder loading chamber, and the cyclone classifier is connected to the powder loading chamber through a powder conveying pipe.

[0012] The melting gas atomization device and the powder loading chamber are filled with an inert protective gas to make it in a low-oxygen environment, which is convenient for the safe use of rare earth powders and the like.

[0013] By setting the cyclone classifier, it is convenient to classify and screen the metal powders produced by melting gas atomization.

[0014] Preferably, the envelope is a cylindrical structure with a closed bottom and an open top, and a lid matching the envelope is provided on the envelope; a convex platform is provided on the lid, and the convex platform is in interference fit with the open top of the envelope.

[0015] The boss on the lid is in interference fit with the top opening of the sheath. When the lid is covered on the sheath, it helps with the pre-encapsulation of the sheath. At the same time, the boss is located in the area to be welded, which can prevent the sheath from being welded through due to improper operation during the electron beam welding process.

[0016] In addition, the traditional powder filling process for vacuum sheaths is completed in the air through an evacuation pipe. Even with the method of vacuum degassing, the impurities in the sheath cannot be completely removed, and after vacuum degassing, the evacuation pipe still needs to be sealed and welded, resulting in low production efficiency of the sheath. Since the sheath of the present invention is in a low-oxygen environment, the choice of whether to set an evacuation pipe on the sheath can be flexible. Especially when the evacuation pipe is not set, the sealing and welding operation of the evacuation pipe is omitted, the production efficiency is improved, and the evacuated sheath can be directly welded and sealed in a vacuum environment, further improving the production efficiency.

[0017] In a second aspect, the present invention provides a method for post-processing powder for a hot isostatic pressing sheath, and the method is implemented based on the above-mentioned powder post-processing system for a hot isostatic pressing sheath; the method for post-processing powder for a hot isostatic pressing sheath includes the following steps:

[0018] (1) Using a melting gas atomization device to melt and atomize metal raw materials to obtain metal powder, transporting the metal powder through a powder conveying pipe into the sheath in the powder filling chamber, placing the sheath on a vibrating table, turning on the vibrating table to compact the powder in the sheath, and covering the lid of the sheath on the sheath;

[0019] (2) Opening the isolation hatch, using a transmission mechanism to transfer the sheath from the powder filling chamber to the welding chamber, closing the isolation hatch, starting a vacuum system to evacuate the welding chamber, and starting an induction heating device to heat the sheath and keep it warm for a period of time and then cool it;

[0020] (3) Starting a welding device to weld the welding area of the cooled sheath to complete the welding and encapsulation of the sheath.

[0021] The present invention completes the encapsulation process of the powder for the hot isostatic pressing sheath through melting, gas atomization powder making, powder filling, compaction, heating and degassing, and welding and encapsulation, with high efficiency; in addition, during the above process, there is no contact with air, preventing the influence of substances such as oxygen, moisture, and oil in the air on the powder in the sheath; furthermore, since the air extraction process of the sheath of the present invention is carried out in a vacuum environment, compared with the existing sheath, the evacuation pipe structure on the sheath can be omitted, and then the sealing and welding operation of the sheath evacuation pipe is omitted, improving the manufacturing efficiency of the sheath; and since the sheath always maintains a low-oxygen environment, it can prevent the oxidation of rare earths during mixing, making it possible to safely use rare earths in the process of manufacturing the sheath. The system and method of the present invention

[0022] Preferably, step (1) further includes subjecting the metal powder to classification screening before conveying it to the powder delivery pipe; step (1) further includes transferring the rare earth powder to the ball mill in the powder loading chamber through the transition chamber, while loading the metal powder into the ball mill through the conveying pipe, loading it into the sleeve after ball milling and mixing, and then covering the lid after compaction.

[0023] Preferably, the rotation speed of the ball mill is 200 - 300 r / min; the vibration frequency for compacting the powder in the sleeve is 20 - 60 Hz, the amplitude is 0.5 - 2 mm, and the compaction density is 60% - 70%.

[0024] Preferably, the rare earth powder is La or Ce.

[0025] Preferably, in step (2), the welding chamber is evacuated to 1×10 -3 ~1×10 -1 Pa; the induction heating device heats the sleeve to 600 - 800 °C, holds for 2 - 5 h, and cools for 0.5 - 1.5 h after the holding ends.

[0026] Preferably, in step (3), the welding is vacuum electron beam welding or TIG welding;

[0027] Among them, the parameters of vacuum electron beam welding are: the accelerating voltage is 40 - 120 kV, the welding beam current is 8 - 80 mA, the focusing beam current is 300 - 3000 mA, and the welding speed is 230° - 1800° / min;

[0028] The parameters of TIG welding are: the welding voltage is 12.6 - 14.4 V, the welding current is 100 - 150 A, the welding speed is 300 - 600° / min, and the pulse frequency is 0.5 - 3 Hz.

[0029] When welding the sleeve, it is usually required that the weld has no any tiny cracks and pores, and has sufficient strength and plasticity to withstand the hot pressing process. The commonly used welding methods include fusion welding, brazing, and solid-phase welding methods such as TIG method (tungsten inert gas shielded welding), MIG method (metal inert gas shielded welding), MAG method (metal active gas shielded welding), laser welding, brazing, diffusion welding, inertia friction welding, friction stir welding, and vacuum electron beam welding, etc. When using the TIG method (tungsten inert gas shielded welding) to weld the sleeve, it has the advantages of preventing the generation of oxide film during the welding process, being suitable for welding thin plate materials, and easy adjustment of welding current, but has shallow penetration, small deposition rate, low productivity, and is not suitable for welding low melting point metals. When using the MIG method (metal inert gas shielded welding) to weld the sleeve, the symmetry of the weld is not as good as that of the TIG method, and spatter is easily generated during welding. The principle of the MAG method (metal active gas shielded welding) is the same as that of the MIG method. The difference is that the shielding gas uses Ar + 20% CO 2, this shielding gas is cheaper than pure Ar, but there are also problems such as low symmetry of the weld seam and easy spatter during welding; Laser welding is a welding method that uses a focused laser beam as the energy to bombard the heat generated by the welded part. It has the advantages of low heat input, small welding deformation, and being unaffected by the electromagnetic field. However, the price of the laser is expensive and the electro-optical conversion efficiency is relatively low (usually less than 10%), which limits the wide application of laser welding. Brazing refers to a welding method in which a filler metal below the melting point of the welded part and the welded part are simultaneously heated to the melting temperature of the filler metal, and then the molten filler metal is used to fill the gaps of the solid workpiece to connect the metals. It has the advantages of no strict limit on the thickness difference of the workpiece, simple equipment, low heating temperature, and simultaneous welding of multiple workpieces. However, the joint strength is low, the heat resistance is poor, and the cleaning requirements for the welding area before welding are strict. Diffusion welding is a solid-state connection method that connects two clean and flat surfaces at high temperature by applying pressure. The most important advantage of diffusion welding is that no melting occurs, and segregation, cracking, and residual stress are effectively eliminated. It can be connected without reducing the strengthening effect of the strengthening phase and maintaining the grain structure. However, in terms of interface reaction, residual stress analysis, joint performance evaluation, and connection process, etc., there is still room for in-depth research. Inertia friction welding generates heat by friction between the materials to be welded. Under the action of the upsetting force, the materials undergo plastic deformation and flow, and then connect the base materials. The process control parameters are few, the heat input is small, the deformation is small, and the weld seam is narrow. It is one of the few processes that can truly achieve a defect rate below 3.4 parts per million. However, the equipment is expensive, the design of the tooling is relatively complex, it is limited to welding parts of rotating bodies, and there are restrictions on the cross-sectional dimensions. Friction stir welding refers to using the heat generated by the friction between a high-speed rotating welding tool and the workpiece to locally melt the material to be welded. When the welding tool moves forward along the welding interface, the plasticized material flows from the front of the welding tool to the rear under the action of the rotational friction force of the welding tool and forms a dense solid-phase weld seam under the extrusion of the welding tool. Friction stir welding has the advantages of low requirements for equipment, small change in the weld zone structure, no need to add welding wire, suitable for dissimilar material welding, and no pollution during the welding process. However, it is not suitable for welding materials less than 3 mm thick, the welded workpiece must be rigidly fixed, and there is a hole left at the end when friction stir welding ends. Vacuum electron beam welding (electronic beam welding, abbreviated as EBW) uses a spatially directed and high-speed moving electron beam to hit the joint of the metal to be welded, converting part of the kinetic energy into heat energy, melting the metal to form a weld seam to achieve welding. Vacuum electron beam welding has the advantages of a small welding area, high efficiency, high weld quality, being suitable for connecting high melting point and dissimilar metals, a large thickness range of the metal to be welded (0.05 mm - 300 mm), and being able to exclude the influence of harmful gases (hydrogen, oxygen) in the atmosphere on the molten metal.Since both TIG welding and vacuum electron beam welding have the advantages of preventing oxidation in the welding area, being suitable for welding high-melting-point metals and thin sheet materials, and TIG welding also has the advantages of low cost, while vacuum electron beam welding has the advantage of a small welding area, for the welding of steel material claddings, the TIG method and vacuum electron beam welding method are preferably used.

[0030] Preferably, the metal raw material is T15 high-speed steel or M2 high-speed steel; the materials of the cladding and the lid are carbon steel or stainless steel; the carbon steel is 45# steel or Q235 steel; the stainless steel is 304 stainless steel or Cr16 ferritic stainless steel.

[0031] When selecting the material of the cladding, it is usually required that it does not react with the powder in the cladding, and the material is as similar as possible to the powder in the cladding. Titanium alloys are widely used in various fields due to their high strength, good corrosion resistance, high heat resistance, etc. They have the advantages of high strength (some high-strength titanium alloys exceed the strength of many alloy structural steels), high thermal strength (the working temperature of titanium alloys can reach 500 °C), good corrosion resistance, good low-temperature performance, high chemical activity, and small thermal conductivity and elasticity, but they have the disadvantages of high price, poor formability, and poor welding performance. Q235 steel has good comprehensive performance due to its low carbon content, and its strength, plasticity, and welding performance are well coordinated, and it is widely used, but it has the disadvantages of poor hardenability, large distortion and cracking tendency, and low thermal strength. Ferritic stainless steel has the advantages of large thermal conductivity coefficient, small expansion coefficient, good oxidation resistance, etc., but it has the disadvantages of poor corrosion resistance and room-temperature brittleness. 304 and 310 stainless steels belong to austenitic stainless steels and have good processing performance and corrosion resistance, and are one of the preferred materials for making metal claddings, but the price of 310 stainless steel is higher than that of 304 stainless steel. 316 stainless steel has a large improvement in its corrosion resistance and high-temperature strength due to the addition of Mo element, and can withstand high temperatures up to 1200 - 1300 degrees, but its price is higher than that of 304 stainless steel. 45# steel has the advantages of low price, high strength, and good machinability, so 45# steel is selected as the cladding material. Therefore, when encapsulating high-speed steel, vacuum claddings made of 45# steel and 304 stainless steel are usually selected.

[0032] Preferably, the powder post-treatment method for the hot isostatic pressing cladding further includes a leak detection process for the welded and encapsulated cladding; the leak detection process includes the following steps:

[0033] Place the cladding in a leak detection device with a vacuum degree of 10 -5 ~10 -4 Pa for 6 - 12 h, and use a vacuum gauge to detect the vacuum degree in the leak detection device. If the vacuum degree changes, it indicates that the cladding leaks. If the vacuum degree remains unchanged, it indicates that the cladding is well sealed.

[0034] Preferably, the leak detection accuracy of the leak detection device is 10-6 mbar·L / S.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] The present invention provides a novel powder post-treatment system for hot isostatic pressing jackets. The encapsulation process of the hot isostatic pressing jacket powder is completed through melting, gas atomization powder making, powder filling, compaction, heating and degassing, and welding and encapsulation. All steps are completed under the protection of a low-oxygen and high-purity environment such as inert gas or vacuum; each link is completed in one container, or sequentially completed in separate containers and then moved to the next container to complete the corresponding link; it can reduce the oxygen content of the metal powder in the jacket; whether to set an evacuation tube on the jacket can be flexibly selected. For jackets without an evacuation tube, since the welding operation of the evacuation tube is omitted, the production efficiency is improved; in a vacuum environment, the evacuated jacket can be directly welded by vacuum electron beam, and the production efficiency is improved. Different from the way of adding rare earths in the traditional casting process, the present invention uses the powder metallurgy method to add rare earths during mixing, and mixes the metal powder and rare earth powder in an inert gas atmosphere, which can prevent the oxidation of rare earths during mixing and make the mixing process safer. Description of the Drawings

[0037] Figure 1 The front view of the system described in Embodiment 1;

[0038] Figure 2 The partial structure diagram of the system described in Embodiment 1;

[0039] Figure 3 The top view of the system described in Embodiment 1;

[0040] Figure 4 The structural schematic diagram of the jacket and the lid;

[0041] Figure 5 The front view of the system described in Embodiment 2;

[0042] Figure 6 The top view of the system described in Embodiment 2;

[0043] Figure 7 The process flow chart of this application.

[0044] In the figure: 1. Powder loading chamber; 2. Welding chamber; 3. Electron beam welding machine; 4. Transition chamber; 5. Isolation hatch; 6. Cladding; 7. Shaking table; 8. Diffusion pump; 9. Powder delivery pipe; 10. Gloves; 11. Guide rail; 12. High-voltage cable; 13. High-voltage power supply; 14. Focusing coil; 15. Deflection coil; 16. Anode; 17. Electron beam welding torch; 18. Gas cylinder; 19. Gas pipe; 20. Welding power supply; 21. TIG welding torch; 22. Clip; 23. Lid; 24. Boss. Detailed implementation manners

[0045] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0046] Unless otherwise specified, the test methods used in the embodiments are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, can all be obtained from commercial channels.

[0047] Embodiment 1

[0048] This embodiment provides a powder post-treatment system for a hot isostatic pressing cladding, as Figure 1 , Figure 2 and Figure 3 shown, including a melting gas atomization device (not shown in the figure), a powder loading chamber 1, and a welding chamber 2 connected in sequence; a cyclone classification device (not shown in the figure) is also connected between the melting gas atomization device and the powder loading chamber 1, and the cyclone classification device is connected to the powder loading chamber 1 through a powder delivery pipe 9. By setting the cyclone classification device, it is convenient to classify and screen the metal powder produced by melting gas atomization.

[0049] A transition chamber 4 is installed outside the powder loading chamber 1, and raw materials can be transferred into the powder loading chamber 1 through the transition chamber 4; a powder delivery pipe 9 connected to the melting gas atomization device is provided in the powder loading chamber 1, and a valve is installed at the end of the powder delivery pipe 9. Through the powder delivery pipe 9, the metal powder can be transported into the powder loading chamber 1. The powder loading chamber 1 is filled with high-purity nitrogen or other inert gases to maintain a low-oxygen environment in the powder loading chamber 1. Gloves 10 for indoor operation are also provided in the powder loading chamber 1. High-purity inert gas is filled into the closed box body, and the active substances therein are cyclically filtered through a gas purification system, so that the water and oxygen contents can both reach below 1 PPM.

[0050] Among them, the gas purification system includes systems such as gas circulation purification and regeneration: The gas circulation purification system includes a high-speed variable-frequency fan and a purification column. The high-speed variable-frequency fan forms a closed loop with the purification column and the processing chamber speed to ensure that the oxygen and water content in the working room is stable within the set range; the regeneration system can activate the purification column for reuse. When a unit purification column reaches saturation, the microcomputer controls the start of other unit purification columns to work, and at the same time starts the regeneration program to regenerate and activate the saturated purification column.

[0051] A vibrating table 7, a jacket 6, and a transmission mechanism provided at the bottom of the vibrating table 7 are also provided in the powder loading chamber 1. The vibrating table 7 is a three-dimensional vibrating platform for compacting the metal powder or mixed powder in the jacket 6. The transmission mechanism connects the powder loading chamber 1 and the welding chamber 2. The transmission mechanism is preferably a guide rail 11. The jacket 6 placed on the vibrating table 7 is transferred from the powder loading chamber 1 to the welding chamber 2 through the transmission mechanism. A ball mill is also provided in the powder loading chamber 1 to facilitate the uniform mixing of powders such as rare earth powders and metal powders transported into the powder loading chamber 1 through the transition chamber 4.

[0052] An isolation hatch 5 for controlling whether the powder loading chamber 1 and the welding chamber 2 are connected is provided between the powder loading chamber 1 and the welding chamber 2. When the isolation hatch 5 is opened, it is convenient for the transmission mechanism to transfer the jacket 6 from the powder loading chamber 1 to the welding chamber 2. When the isolation hatch 5 is closed, relatively independent and airtight working areas are provided for the powder loading chamber 1 and the welding chamber 2 respectively.

[0053] The welding chamber 2 is connected to a vacuum system for providing a vacuum environment in the welding chamber 2; a diffusion pump 8 is connected outside the welding chamber 2. An induction heating device and a welding device are provided in the welding chamber 2. An induction coil is installed on the induction heating device, and the induction coil can be freely installed outside the jacket 6. The welding device is a vacuum electron beam welding device, that is, an electron beam welder 3, including a high-voltage cable 12, a high-voltage power supply 13, a focusing coil 14, a deflection coil 15, an anode 16, and an electron beam welding gun 17.

[0054] The weight of the jacket 6 is 10-15 kg, the material of the jacket 6 is carbon steel or stainless steel, and the structure of the jacket 6 is as Figure 4As shown in the figure, the jacket 6 is a cylindrical structure with a closed bottom and an open top. The diameter of the jacket 6 is 100 - 200 mm, the thickness of the jacket 6 is 1 - 5 mm, and the height of the jacket 6 is 150 - 300 mm. A lid 23 that mates with the jacket 6 is provided on the jacket 6. The lid 23 is disc-shaped. An evacuation tube may or may not be provided on the lid 23. The material of the lid 23 is carbon steel or stainless steel. The diameter of the lid 23 is 100 - 200 mm, the thickness of the lid 23 is 1 - 5 mm. There is a boss 24 with a diameter of 95 - 195 mm on the lid 23, and the thickness of the boss 24 is 1 - 3 mm. The boss 24 of the lid of the jacket 6 is in interference fit with the top opening of the jacket 6. The area to be welded is the joint between the lid 23 and the jacket 6 and the evacuation tube. The design of the boss 24 on the lid 23 helps with the pre-packaging of the jacket 6 and can prevent the jacket 6 from being welded through due to improper operation during the electron beam welding process.

[0055] Example 2

[0056] This example provides a powder post-treatment system for a hot isostatic pressing jacket, as Figure 5 and Figure 6 shown. The difference from Example 1 lies in the welding equipment in the welding chamber 2. The welding equipment in this example is a TIG welding equipment, including a gas cylinder 18, a gas pipe 19, a welding power source 20, a TIG welding torch 21, and a clamp 22.

[0057] Example 3

[0058] This example provides a method for powder post-treatment using the powder post-treatment system for a hot isostatic pressing jacket described in Example 1 or 2, as Figure 7 shown, including the following steps:

[0059] (1) Use a vacuum induction melting gas atomization (VIGA) device to melt and atomize the metal raw materials to make powder; use a cyclone classifier to classify the obtained metal powder, and the classified metal powder enters the powder loading chamber 1 through the powder conveying pipe 9; or directly input the metal powder in the powder collection tank of the vacuum induction melting gas atomization device into the powder loading chamber 1 through the powder conveying pipe 9.

[0060] Among them, the metal raw material is T15 high-speed steel or M2 high-speed steel. The cyclone classification device can classify the powder and drive the powder into the powder conveying pipe 9. During the classification process, the high-speed airflow carries the solid particles to be classified and enters the separator tangentially. The airflow makes a high-speed rotational motion along the inner wall of the circular separator. Under the action of strong centrifugal force, the coarse particles in the material rotate downward along the conical inner wall of the separator and sink to the lower discharge port for discharge. The fine particles concentrate towards the center of the separator due to the action of centripetal force and rise with the airflow or liquid flow and are discharged from the upper outlet, thus achieving the purpose of classifying coarse and fine particles. The inlet velocity of the material and airflow into the cyclone separator in the cyclone classification device is 10 - 25 m / s. Different particle size powders can be selected based on different process requirements through the cyclone classification device. For example, powders with a particle size of 15 - 53 μm are used in the selective laser melting process, powders with a particle size of 45 - 105 μm are used in electron beam printing, and powders with a particle size of 0 - 150 μm are used in ordinary powder metallurgy.

[0061] The powder conveying pipe 9 is between the vacuum induction melting gas atomization device and the glove box, and a valve is installed at the end of the powder conveying pipe 9; the metal powder in the powder conveying pipe 9 and the powder collection tank can enter the powder collection chamber from the top, side or bottom of the glove box; the glove box is composed of a powder loading chamber 1, a welding chamber 2 and a transition chamber 4. The glove box is filled with high-purity nitrogen or other inert gases, and raw materials can be transferred into the glove box through the transition chamber 4.

[0062] (2) Place the sleeve 6 on the vibrating table 7, inject the metal powder in the powder conveying pipe 9 or the powder collection tank into the sleeve 6. While injecting the powder into the sleeve 6, turn on the vibrating table 7 to compact the powder. The vibration frequency is 20 - 60 Hz, and the amplitude is 0.5 - 2 mm. Finally, the sleeve 6 is filled with powder, and the total weight is weighed to make the tap density 60% - 70%.

[0063] Among them, the weight of the sleeve 6 is 10 - 15 kg, the material of the sleeve 6 is carbon steel or stainless steel, the shape of the sleeve 6 is cylindrical, the diameter of the sleeve 6 is 100 - 200 mm, the thickness of the sleeve 6 is 1 - 5 mm, and the height of the sleeve 6 is 150 - 300 mm.

[0064] Or weigh a certain amount of rare earth powder, transfer it from the transition chamber 4 to the ball mill tank in the glove box, weigh a certain weight of metal powder, load the metal powder into the ball mill tank, install the ball mill tank on the ball mill and mix for 6 - 12 h, and cool for 1 - 2 h after mixing. Among them, the amount of rare earth powder accounts for 0.01 wt% - 0.06 wt% of the total amount; after mixing the rare earth element with the high-speed steel powder, La and Ce in the rare earth element can replace V in the high-speed steel, reducing the cost of high-speed steel.

[0065] Then, place the cladding 6 on the vibrating table 7, fill the cladding 6 with the mixed powder of rare earth and high-speed steel. While filling the powder, start the vibrating table 7 to compact the powder. The vibration frequency is 20 - 60 Hz, and the amplitude is 0.5 - 2 mm. Finally, the powder fills the cladding 6, weigh the total weight to make the tap density 60% - 70%.

[0066] Among them, the rare earth powder is La or Ce, the rotation speed of the ball mill is 200 - 300 r / min; the weight of the cladding 6 is 10 - 15 kg, the material of the cladding 6 is carbon steel or stainless steel, the shape of the cladding 6 is cylindrical, the diameter of the cladding 6 is 100 - 200 mm, the thickness of the cladding 6 is 1 - 5 mm, and the height of the cladding 6 is 150 - 300 mm.

[0067] (3) Place the cladding 6 on the vibrating table 7, install the lid 23 of the cladding 6 on the cladding 6, use the transmission mechanism to transfer the cladding 6 into the welding chamber 2, then close the isolation hatch 5 between the powder filling chamber 1 and the welding chamber 2, start the vacuum system to evacuate the welding chamber 2 to 1×10 -3 ~1×10 -1 Pa. While evacuating, start the induction heating equipment to heat the cladding 6 to 600 - 800 °C, keep it warm for 2 - 5 h. After the heat preservation ends, cool it for 0.5 - 1.5 h. Start the vacuum system in the electron beam welding gun to evacuate the electron beam welding gun to 5×10 -4 ~5×10 -3 Pa, and perform vacuum electron beam welding on the area to be welded.

[0068] Among them, the lid 23 of the cladding 6 is disk-shaped. An evacuation tube can be provided or not provided on the lid 23. The material of the lid 23 is carbon steel or stainless steel. The diameter of the lid 23 is 100 - 200 mm, the thickness of the lid 23 is 1 - 5 mm. There is a boss 24 with a diameter of 95 - 195 mm on the lid 23, and the thickness of the boss 24 is 1 - 3 mm. The lid 23 of the cladding 6 and the cladding 6 are in interference fit. The area to be welded is the joint between the lid 23 and the cladding 6 and the evacuation tube. The area to be welded has been pre-treated in advance; the induction heating equipment has an induction coil, which can be freely installed outside the cladding 6. The acceleration voltage of the vacuum electron beam welding is 40 - 120 kV, the welding beam current is 8 - 80 mA, the focusing beam current is 300 - 3000 mA, and the welding speed is 230° - 1800° / min.

[0069] Or place the cladding 6 on the vibrating table 7, install the lid 23 of the cladding 6 on the cladding 6, use the transmission mechanism to transfer the cladding 6 into the welding chamber 2, then close the isolation hatch 5 between the powder filling chamber 1 and the welding chamber 2, start the vacuum system to evacuate the cladding 6 to 1×10 -3 ~1×10 -1While evacuating to Pa, turn on the induction heating equipment to heat the jacket 6 to 600 - 800 °C, keep it warm for 2 - 5 h, and after the heat preservation ends, cool it for 0.5 - 1.5 h, then perform TIG welding on the area to be welded.

[0070] Among them, the area to be welded is the joint of the lid 23 and the jacket 6 and the evacuation pipe. The area to be welded has been pretreated in advance. The welding voltage is 12.6 - 14.4 V, the welding current is 100 - 150 A, the welding speed is 300 - 600 ° / min, and the pulse frequency is 0.5 - 3 Hz.

[0071] (4) Place the jacket 6 in a container of a leak detection device, start the vacuum system on the container to evacuate to 10 -5 ~10 -4 Pa, then turn off the vacuum system. After placing it for 6 - 12 h, use a vacuum gauge to detect the vacuum degree in the container. It is found that the appearance of the jacket 6 is intact and there is no air leakage.

[0072] Example 4

[0073] This example provides a powder post - treatment method for a hot isostatic pressing jacket, including the following steps:

[0074] (1) Use a vacuum induction melting gas atomization (VIGA) device to melt and atomize the M2 metal raw material into powder; use a cyclone classifier to classify the obtained M2 high - speed steel powder. The classified M2 high - speed steel powder enters the powder loading chamber 1 in the glove box filled with argon protection through the powder conveying pipe 9; or directly input the M2 high - speed steel powder in the powder collection tank of the atomization device into the powder loading chamber 1.

[0075] (2) Place the jacket 6 on the vibrating table 7, and inject the high - speed steel powder in the powder collection tank into the cylindrical 304 stainless steel jacket 6 with a weight of 11.4 kg, a diameter of 120 mm, a height of 200 mm, and a thickness of 3 mm from the side. While injecting the powder into the jacket 6, turn on the vibrating table 7 to compact the powder. The vibration frequency is 37 Hz and the amplitude is 0.8 mm. Finally, the powder fills the jacket 6, weigh the total weight, and obtain a tap density of 67%.

[0076] (3) Place the jacket 6 on the workbench, install the disc - shaped 304 stainless steel lid 23 with a diameter of 120 mm and a thickness of 3 mm and a boss 24 with a diameter of 115 mm and a thickness of 2 mm on the jacket 6. Use the transmission mechanism to transfer the jacket 6 to the welding chamber 2 through the guide rail 11, and then close the isolation hatch 5 between the powder loading chamber 1 and the welding chamber 2; start the vacuum system to evacuate the welding chamber 2 to 1×10 -2While evacuating to a vacuum, turn on the induction heating equipment to heat the jacket 6 to 600 °C, hold for 2 h, and after the holding is completed, cool for 0.5 h. Perform TIG welding on the area to be welded. The welding voltage is 13.5 V, the welding current is 135 A, the welding speed is 350 ° / min, and the pulse frequency is 1.8 Hz.

[0077] (4) Place the jacket 6 in a container with dimensions of 400×200×200 mm. Start the vacuum system on this container to evacuate to 10 -5 Pa, then close the vacuum system. After placing it for 9 h, use a vacuum gauge to detect the vacuum degree inside the container. It is found that the appearance of the jacket 6 is intact and there is no air leakage.

[0078] Example 5

[0079] This example provides a powder post-treatment method for a hot isostatic pressing jacket, including the following steps:

[0080] (1) Use a vacuum induction melting gas atomization (VIGA) device to melt and atomize the T15 metal raw material into powder; use a cyclone classifier to classify the obtained T15 high-speed steel powder. The classified T15 high-speed steel powder enters the powder loading chamber 1 in the glove box through the powder conveying pipe 9; or directly input the T15 high-speed steel powder in the powder collection tank of the atomization device into the powder loading chamber 1.

[0081] (2) Weigh a certain amount of La or Ce powder, transfer it from the transition chamber 4 to the ball milling tank in the glove box filled with nitrogen protection, then open the valve at the end of the powder conveying pipe 9, weigh a certain weight of high-speed steel powder, and load the high-speed steel powder into the ball milling tank; install the ball milling tank on the ball mill and mix for 6 h. After mixing is completed, cool for 1 h. Then place the jacket 6 on the vibrating table 7, and load the mixed powder of rare earth and high-speed steel into a cylindrical 45# steel jacket 6 with a weight of 11.4 kg, a diameter of 120 mm, a height of 200 mm, and a thickness of 3 mm. While loading the powder, turn on the vibrating table 7 to compact the powder. The vibration frequency is 42 Hz and the amplitude is 1 mm. Finally, the powder fills the jacket 6, weigh the total weight, and obtain a tap density of 65%.

[0082] (3) Place the jacket 6 on the vibrating table 7, install a disc-shaped 45# steel lid 23 with a diameter of 120 mm and a thickness of 3 mm and having a boss 24 with a diameter of 115 mm and a thickness of 2 mm on the jacket 6. Use the transmission mechanism to transfer the jacket 6 through the guide rail 11 to the welding chamber 2, and then close the isolation hatch 5 between the powder loading chamber 1 and the welding chamber 2; start the vacuum system to evacuate the welding chamber 2 to 1×10 -2 Pa. While evacuating to a vacuum, turn on the induction heating equipment to heat the jacket 6 to 600 °C, hold for 2 h, and after the holding is completed, cool for 0.5 h.

[0083] Start the vacuum system in the electron beam welding torch to evacuate the electron beam welding torch to 1×10 -3 Pa, perform vacuum electron beam welding on the area to be welded, with an acceleration voltage of 50 kV, a welding beam current of 70 mA, a focusing beam current of 375 mA, and a welding speed of 470° / min.

[0084] Alternatively, perform TIG welding on the area to be welded, with a welding voltage of 13.5 V, a welding current of 135 A, a welding speed of 350° / min, and a pulse frequency of 1.8 Hz.

[0085] (4) Place the jacket 6 in a container with dimensions of 400×200×200 mm, start the vacuum system on the container to evacuate it to 10 -5 Pa, then close the vacuum system. After placing it for 9 h, use a vacuum gauge to detect the vacuum degree inside the container. It is found that the appearance of the jacket 6 is intact and there is no air leakage. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A powder post-treatment system for a hot isostatic pressing jacket, characterized in that, it includes a melting gas atomization device, a powder loading chamber, and a welding chamber connected in sequence; a powder delivery pipe connected to the melting gas atomization device is provided in the powder loading chamber, and a vibrating table, a jacket, and a transmission mechanism provided at the bottom of the vibrating table are also provided in the powder loading chamber, and the transmission mechanism connects the powder loading chamber and the welding chamber; an isolation hatch for controlling whether the powder loading chamber and the welding chamber are communicated is provided between the powder loading chamber and the welding chamber; the welding chamber is connected with a vacuum system, and an induction heating device and a welding device are provided in the welding chamber; the melting gas atomization device and the powder loading chamber are filled with a protective gas, and the protective gas is an inert gas; no evacuation pipe is provided on the jacket; the jacket is a cylindrical structure with a closed bottom and an open top, and a lid matching the jacket is provided on the jacket; a boss is provided on the lid, and the boss is in interference fit with the top opening of the jacket.

2. The powder post-treatment system for a hot isostatic pressing jacket according to claim 1, characterized in that, the powder post-treatment system for a hot isostatic pressing jacket further includes a transition chamber communicated with the powder loading chamber, and a ball mill is also provided in the powder loading chamber.

3. The powder post-treatment system for a hot isostatic pressing jacket according to claim 1, characterized in that, a cyclone classifier is further connected between the melting gas atomization device and the powder loading chamber, and the cyclone classifier is connected to the powder loading chamber through a powder delivery pipe.

4. A powder post-treatment method for a hot isostatic pressing jacket, characterized in that, the method is implemented based on the treatment system according to any one of claims 1 to 3, and includes the following steps: (1) Using the melting gas atomization device to melt and atomize the metal raw material to obtain metal powder, transporting the metal powder through the powder delivery pipe into the jacket in the powder loading chamber, placing the jacket on the vibrating table, turning on the vibrating table to compact the powder in the jacket, and covering the lid of the jacket on the jacket; (2) Opening the isolation hatch, using the transmission mechanism to transfer the jacket from the powder loading chamber to the welding chamber, closing the isolation hatch, starting the vacuum system to evacuate the welding chamber, and starting the induction heating device to heat the jacket and keep it warm for a period of time and then cool it; (3) Starting the welding device to weld the welding area of the cooled jacket to complete the welding and encapsulation of the jacket.

5. The powder post-treatment method for a hot isostatic pressing jacket according to claim 4, characterized in that, the step (1) further includes performing classification and screening treatment on the metal powder before transporting it to the powder delivery pipe; the step (1) further includes transferring the rare earth powder through the transition chamber to the ball mill in the powder loading chamber, and at the same time loading the metal powder into the ball mill through the powder delivery pipe, mixing by ball milling and then loading it into the jacket, and then covering the lid after compaction.

6. The powder post-treatment method for a hot isostatic pressing jacket according to claim 5, characterized in that, the rotation speed of the ball mill is 200 - 300 r / min; the vibration frequency for compacting the powder in the jacket is 20 - 60 Hz, the amplitude is 0.5 - 2 mm, and the compaction density is 60% - 70%.

7. The powder post-treatment method for a hot isostatic pressing jacket according to claim 4, characterized in that, In step (2), the welding chamber is evacuated to 1×10 -3 ~1×10 -1 Pa; the induction heating equipment heats the jacket to 600 - 800 °C, holds the temperature for 2 - 5 h, and cools for 0.5 - 1.5 h after the heat preservation ends.

8. The post-treatment method for powder for a hot isostatic pressing jacket as described in claim 4, characterized in that, in the step (3), the welding is vacuum electron beam welding or TIG welding; the parameters of the vacuum electron beam welding are: the accelerating voltage is 40 - 120 kV, the welding beam current is 8 - 80 mA, the focusing beam current is 300 - 3000 mA, and the welding speed is 230° - 1800° / min; the parameters of the TIG welding are: the welding voltage is 12.6 - 14.4 V, the welding current is 100 - 150 A, the welding speed is 300 - 600° / min, and the pulse frequency is 0.5 - 3 Hz.

9. The post-treatment method for powder for a hot isostatic pressing jacket as described in claim 4, characterized in that, it further includes a leak detection process for the jacket after welding and encapsulation; the leak detection process includes the following steps: Place the shroud in a leak detection device with a vacuum of 10 -5 ~10 -4 Pa for 6 - 12 h. Use a vacuum gauge to detect the vacuum inside the leak detection device. If the vacuum changes, it indicates that the shroud is leaking. If the vacuum remains unchanged, it indicates that the shroud is well-sealed.

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