Intermediate alloy vacuum hot pressing furnace

Abstract

The utility model discloses an intermediate alloy vacuum hot pressing furnace. An induction coil and a cooling cavity are additionally arranged on an original structure. And an external pipe is mounted behind the furnace body in an insulated and sealed manner and is in sealed connection with an induction coil outside the mold through a quick-change connector. A cooling cavity with a spherical or cambered top is designed at the bottom of the base, a gas inlet pipe and a gas outlet pipe are arranged at the furnace bottom of the cooling cavity, an outlet of the gas inlet pipe is aligned with the spherical top surface or the cambered top surface of the cooling cavity, and nitrogen or other non-flame-retardant gases are introduced into the cooling cavity. For the intermediate alloy without ferromagnetism, a ferromagnetic heating ring is additionally arranged between the induction coil and the die. Only the intermediate alloy is heated, so that the compression bar cannot be deformed and damaged due to high temperature. And non-flame-retardant gas directly cools the graphite base, so that the manufacturing efficiency of the intermediate alloy is improved.

Description

Technical Field

[0001] The utility model is applied to the field of new metal materials, and relates to nanometer particle reinforced metal materials, in particular to a hot pressing furnace for making nanometer particles into intermediate alloys. Background Art

[0002] Nanoparticles can be added to metal materials as a reinforcing phase, effectively enhancing the mechanical properties of steel and representing an innovative method for strengthening metal materials. However, nanoparticles easily agglomerate and are difficult to evenly distribute in molten steel, resulting in poor performance enhancement. To address this issue, an aluminum-based master alloy containing pre-dispersed, endogenous nanoparticles is used as a carrier for the nanoparticles. The master alloy is placed at the bottom of a ladle and then, during tapping, is dispersed by the molten steel in an intermediate frequency furnace. This involves melting the aluminum matrix at high temperatures, and the nanoparticles are then evenly dispersed by the stirring action of the molten steel. The aluminum-based master alloy production process involves uniform mixing, powder compacting, and vacuum high-temperature hot pressing. The uniform mixing process involves mixing the nanomaterial (typically TiC or TiC + TiB2) with aluminum powder in a ball mill. Powder compacting involves pressure forming in a cold liquid mold. Vacuum high-temperature hot pressing involves semi-melting the aluminum powder in a vacuum hot pressing furnace, applying high pressure, and then cooling the powder in the furnace to form the final product.

[0003] The structure of the vacuum hot pressing furnace used to make the master alloy is shown in the attached figure. Figure 1 and attached Figure 2 As shown, a cold-pressed aluminum master alloy is wrapped in graphite paper and placed in a mold 5. The pressure is then evacuated through a vacuum port 6 to below 10 MPa. The electric heater 3, connected to an external electrical connector 8, is then powered and heated. Once the temperature and time parameters are met, a hydraulic cylinder 1 is pressed downward, and a pressure rod 7 compresses the semi-molten aluminum master alloy under high pressure. The hydraulic cylinder 1 then retracts, and the hot-pressed master alloy cools in a vacuum furnace to a temperature of 200-300°C. The furnace door 9 is then opened, and the vacuum is broken to remove the master alloy. This vacuum hot-pressing furnace suffers from the following issues: 1) The pressure rod has low high-temperature strength, making it susceptible to deformation and damage under pressure; 2) The vacuum furnace has a long cooling time, resulting in low master alloy production efficiency.

[0004] To address the issues of long cooling times and low efficiency, CN214582526U describes a dual-station vacuum induction hot-pressing furnace. This furnace utilizes dual stations to improve efficiency and a water-cooling structure to protect the pressing rods. The furnace shell is a sandwich structure, with cooling water flowing inside to improve cooling efficiency. CN219121093U describes a three-station vacuum induction hot-pressing furnace with one hot-pressing station and three cooling stations to improve production efficiency. Utility Model Content

[0005] The technical problem solved by the utility model is to provide a vacuum hot pressing furnace for master alloys, which induction heats the master alloy while keeping the pressing rods unheated, thereby solving the problem of insufficient strength of the pressing rods during pressing. Cooling gas is used at the bottom of the base to increase the cooling rate of the master alloy and improve the production efficiency of the master alloy.

[0006] The technical solution adopted by the present invention is as follows: the intermediate alloy vacuum hot pressing furnace is formed by adding an induction coil and a cooling cavity to the original furnace body structure. Two through holes are processed at the back of the furnace body, and an external pipe is installed in an insulated and sealed manner. The external pipe is sealed and connected to the induction coil via a quick-change joint. The induction coil is arranged on the outside of the graphite mold. After power is turned on, the induction coil can directly heat the intermediate alloy. A cooling cavity is designed at the bottom of the base, which is sealed and fixedly connected to the furnace bottom. The top of the cooling cavity is spherical or curved to meet the pressure requirements. The furnace bottom of the cooling cavity is provided with an air inlet pipe and an air outlet pipe.

[0007] Furthermore, the outlet of the inlet pipe is aligned with the spherical or arcuate top surface of the cooling cavity. Valves are installed on the inlet and outlet pipes, which not only control the flow of gas but also indirectly affect the vacuum level within the furnace. Nitrogen or other non-flame-retardant gases are introduced into the inlet pipe to avoid adverse effects on the high-temperature master alloy.

[0008] Furthermore, for the non-ferromagnetic master alloy, a ferromagnetic heating ring is added between the induction coil and the mold, and the heat is inductively transferred to the master alloy through the heating ring.

[0009] Furthermore, the refractory lining and heating elements in the furnace are basically useless, as long as the base and the furnace bottom are sealed, so the furnace body can be replaced with a furnace shell.

[0010] The beneficial effects of the present invention are as follows: the present invention only heats the master alloy, and the pressure rod will not be deformed or damaged due to high temperature. The non-flame retardant gas directly cools the graphite base, resulting in a fast cooling speed and improved production efficiency of the master alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural diagram of an existing vacuum hot pressing furnace;

[0012] Figure 2 for Figure 1 AA cross-sectional view of ;

[0013] Figure 3 This is a schematic front view of Example 1;

[0014] Figure 4 for Figure 3 BB cross-sectional diagram;

[0015] Figure 5 This is a schematic front view of Example 2;

[0016] In the figure: 1- hydraulic cylinder, 2- furnace body, 3- electric heating element, 4- base, 5- mold, 6- vacuum port, 7- pressure rod, 8- electrical connector, 9- furnace door;

[0017] 11-induction coil, 12-cooling cavity, 13-outlet pipe, 14-inlet pipe, 15-valve, 16-external pipe, 17-quick-change connector, 18-heating ring. DETAILED DESCRIPTION

[0018] The utility model is a transformation based on the original vacuum hot pressing furnace, but the technical solution is not limited to vacuum hot pressing furnaces. Example 1

[0019] The structure of the intermediate alloy vacuum hot pressing furnace in this embodiment is shown in the attached figure. Figure 3 and attached Figure 4 As shown, an induction coil 11 and a cooling cavity 12 are added to the original furnace structure.

[0020] Two through-holes are machined in the rear of the furnace body 2 to allow for the installation of an external tube 16, which is insulated and sealed. This tube is connected to the induction coil 11 via a quick-change connector 17, facilitating replacement of the induction coil 11. The induction coil 11 is placed outside the graphite mold 5 and in close proximity to the mold to maximize the sensing of the master alloy within the mold.

[0021] The mold 5 is positioned and placed on the upper surface of the base 4 in the furnace, and the base 4 is also made of graphite. The base 4 is sealed and fixedly connected to the refractory layer at the bottom of the furnace. A cooling cavity 12 is designed at the bottom of the base 4. To ensure the compressive strength of the base, the top of the cooling cavity 12 should be spherical or curved. An air inlet pipe 14 and an air outlet pipe 13 are provided at the bottom of the cooling cavity 12. In order to enhance the cooling rate of the intermediate alloy, the outlet of the air inlet pipe 14 should be close to and aligned with the spherical top surface or the curved top surface of the cooling cavity 12. Valves 15 are installed on the air inlet pipe 14 and the air outlet pipe 13. The air outlet pipe 13 is used to relieve the pressure of the gas in the cooling cavity 12.

[0022] When the present invention is used, since the intermediate alloy cannot be directly measured in temperature (the temperature measuring element is set in the mold, which is easy to be damaged when pressing the intermediate alloy), it is advisable to measure the relationship curve between temperature and induction power according to the actual ratio of metal particles in the intermediate alloy before making the intermediate alloy, and use power and time to replace temperature. The specific method is: the intermediate alloy after cold pressing is placed in the mold, and the coupler or temperature measuring component is placed at the same time, and the intermediate alloy is heated by high power induction. After reaching the set temperature, the power is reduced to keep warm. After the relationship curve between induction power and temperature is determined by experiment, the intermediate alloy is hot pressed. It should be noted that: 1) The quick-change joint is only for the need to replace the induction coil. Before the vacuum hot pressing furnace is operated, water must be passed through the pressurized water to check the sealing of the quick-change joint. 2) The replacement of the induction coil, the replacement of the graphite mold, the replacement of the graphite base, etc., all require the measurement of the relationship curve between the induction heating temperature and the induction power of the intermediate alloy. After all, the thermal conductivity of graphite is relatively high.

[0023] After the master alloy is hot-pressed, an air inlet pipe 14 delivers nitrogen or other non-combustible gas into the cooling cavity 12. The outlet of the air inlet pipe directly cools the spherical or curved top of the mold below, directly cooling the graphite base. In a vacuum furnace, low-temperature cooling at temperatures below 500°C primarily relies on conduction, so the cooling rate of the base directly determines the cooling rate of the master alloy. It should be noted that: 1) when the vacuum hot-pressing furnace is evacuated, valve 15 is closed; when cooling gas is introduced, valve 15 is opened to prevent poor sealing between the base and the furnace bottom, which could result in insufficient vacuum within the furnace. 2) Even if poor sealing between the base and the furnace bottom allows gas to enter the vacuum furnace, since it is non-combustible, it will not adversely affect the master alloy. 3) The master alloy is wrapped in graphite paper, and the pressing head is aligned with the mold cavity. During the master alloy cooling process, even if gas enters the furnace, it will not adversely affect the master alloy. Example 2

[0024] Example 1: For the case where the master alloy has ferromagnetism and can be induction heated, for the master alloy that cannot be directly induction heated, the following method is used. Figure 5 In this method, a heating ring 18 is added between the induction coil 11 and the mold 5. This heating ring 18 is ferromagnetic and can directly heat the master alloy through induction. The induction coil 11 induction-heats the heating ring 18, which then radiates and heats the mold 5, which then conducts and heats the master alloy. Before hot-pressing the master alloy, it is advisable to first test and determine the relationship between induction power and master alloy temperature.

[0025] This utility model is a modification of an existing vacuum hot-pressing furnace. Relatively speaking, a vacuum hot-pressing furnace merely provides a vacuum chamber within which an induction heating device is installed. The purpose of this modification is to directly utilize the existing vacuum hot-pressing furnace's hydraulic system. The refractory lining, heating elements, and other components within the vacuum hot-pressing furnace play no role in this utility model. A sealed connection between the base and the furnace floor, such as by threading or bonding, is sufficient. In other words, replacing the furnace body with a furnace shell will also satisfy the requirements of this utility model.

[0026] This new design uses induction heating to heat only the master alloy, leaving the pressure rod unheated, meeting the strength requirements of hot pressing without deformation or damage. The graphite base has good thermal conductivity and is cooled using non-flame-retardant gas, resulting in a fast cooling rate and improved master alloy production efficiency.

Claims

1. A vacuum hot pressing furnace for intermediate alloys, characterized in that: Two through holes are processed at the back of the furnace body, and an external pipe (16) is installed in an insulated and sealed manner. The external pipe (16) is sealed and connected to the induction coil (11) through a quick-change joint (17). The induction coil (11) is arranged on the outside of the graphite mold; a cooling cavity (12) is designed at the bottom of the base that is sealed and fixedly connected to the bottom of the furnace. The top of the cooling cavity (12) is spherical or arc-shaped, and the bottom of the cooling cavity (12) is provided with an air inlet pipe (14) and an air outlet pipe (13).

2. The master alloy vacuum hot pressing furnace according to claim 1, characterized in that: The outlet of the air inlet pipe (14) is aligned with the spherical top surface or the arc top surface of the cooling cavity (12).

3. The master alloy vacuum hot pressing furnace according to claim 1, characterized in that: Valves (15) are installed on the air inlet pipe (14) and the air outlet pipe (13).

4. The master alloy vacuum hot pressing furnace according to claim 1, characterized in that: Nitrogen or other non-flame-retardant gases are introduced into the air inlet pipe (14).

5. The master alloy vacuum hot pressing furnace according to claim 1, characterized in that: A ferromagnetic heating ring (18) is added between the induction coil (11) and the mold.

6. The master alloy vacuum hot pressing furnace according to claim 1, characterized in that: The furnace body is replaced with a furnace shell.

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