Vertical hot extrusion high-vacuum system for bismuth telluride thermoelectric material

Abstract

The vertical hot extrusion high-vacuum system for the bismuth telluride thermoelectric material comprises a vertical vacuum cavity body, four supporting lugs used for fixing an extrusion die are arranged on the inner side of the bottom wall of the vacuum cavity body, the supporting lugs are evenly arranged on the same circumference at intervals with a discharging opening as the circle center, grooves are formed in the inner sides of the supporting lugs, and the supporting lugs are arranged in the grooves. The extrusion die is cylindrical, and convex lugs matched with the grooves in the supporting lugs are arranged on the outer side of the bottom of the extrusion die, so that the extrusion die is screwed into the grooves of the supporting lugs through the convex lugs and is detachably fixed to the inner side of the bottom wall of the vacuum cavity body. And a mold supporting lug is designed in the cavity. And the mold can be reliably separated from a product during the return stroke of the main shaft, so that the demolding adhesion problem is effectively solved, the shapes of the mold and the product are protected, the production period is shortened, and the automation degree and reliability of equipment operation are improved.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric material preparation technology in the field of thermoelectric power generation technology, and particularly relates to the field of hot extrusion preparation of bismuth telluride (Bi2Te3) thermoelectric materials. Background Technology

[0002] Thermoelectric materials are functional materials capable of directly converting heat energy into electrical energy. Thermoelectric power generation and refrigeration devices made from them possess outstanding advantages such as compact structure, no moving parts, no noise, high reliability, and environmental friendliness, showing broad application prospects in fields such as space power, industrial waste heat recovery, and localized precision refrigeration. Among numerous thermoelectric materials, bismuth telluride and its solid solution materials possess the highest thermoelectric figure of merit (ZT value) in the near-room temperature range, making it the most mature and widely used thermoelectric material system in commercial applications.

[0003] The preparation of high-performance bismuth telluride bulk materials typically employs a process route of melting-crushing-sintering or hot pressing / hot extrusion. Among these, hot extrusion is considered a highly promising technology due to its ability to effectively refine grains and densify materials through intense plastic deformation and dynamic recrystallization. Furthermore, its strong directional forming capability induces grains to align in a specific direction, significantly enhancing the thermoelectric properties of the material along the extrusion direction. However, this technology faces a core challenge: bismuth telluride materials require extrusion at high temperatures of 400-500℃ to achieve sufficient plastic flow and orientation of the grains. At this temperature, the material is highly susceptible to oxidation and thermal decomposition, necessitating extrusion in a high-vacuum environment.

[0004] Currently, mainstream horizontal hot extrusion equipment has the following inherent defects: (1) Poor sealing performance. The complex dynamic sealing structure is prone to failure under high temperature and high pressure, making it difficult to maintain the required high vacuum level, which leads to material oxidation. (2) Poor uniformity. In the horizontal structure, the mold and barrel are deflected due to their own weight, resulting in unstable material flow, easy defects, and increased risk of component segregation and contamination. (3) Low system integration. Heating, pressurization, vacuum and other systems are mostly simple assembly, lacking integrated collaborative control, resulting in poor process stability and repeatability. (4) High equipment cost. The misalignment caused by gravity increases the precision requirements and cost of equipment manufacturing and maintenance.

[0005] These defects severely restrict the application of hot extrusion technology in the industrial-scale preparation of high-quality bismuth telluride materials. Summary of the Invention

[0006] Compared with the prior art, the present invention provides a vertical hot extrusion high vacuum system for bismuth telluride thermoelectric materials. Through its unique vertical structure and integrated design, it effectively overcomes the inherent defects of traditional horizontal equipment, bringing about significant performance improvement and process improvement.

[0007] This invention is implemented as follows: a vertical hot extrusion high vacuum system for bismuth telluride thermoelectric materials includes a vertical vacuum chamber body. A cavity door for installing and debugging internal system components is installed on the side wall of the vacuum chamber body. An electrical and gas connection port connected to the inner cavity of the vacuum chamber body is also opened on the side wall of the vacuum chamber body. An opening for installing the extrusion shaft of the hot extrusion host is opened on the top wall of the vacuum chamber body. A dynamic sealing structure is provided in the opening. A detachable extrusion mold is installed on the inner side of the bottom wall of the vacuum chamber body. An outlet for extruding the extruded material rod is provided on the outer side of the bottom wall of the vacuum chamber body, which communicates with the extrusion mold.

[0008] Furthermore, the cavity door is a side-opening door, connected to the vacuum cavity body by two hinges, and a sealing ring is provided on the inside of the cavity door.

[0009] Furthermore, a door handle is provided on the outside of the cavity.

[0010] Furthermore, the discharge port is sealed by a vacuum blind flange.

[0011] Furthermore, a mechanical pump and a molecular pump connected to the electrical and gas connection ports are installed on the outside of the vacuum chamber body for extracting gas from the vacuum chamber.

[0012] Furthermore, a positioning ear is provided on the lower outer side of the vacuum chamber body for fixing the vacuum chamber body onto the support platform of the hot extrusion machine.

[0013] Furthermore, the opening diameter is over 200mm, and the dynamic sealing structure uses three sealing rings and two sealing gaskets.

[0014] Furthermore, the inner side of the bottom wall of the vacuum chamber body is provided with four support ears for fixing the extrusion mold. The support ears are evenly arranged on the same circumference with the discharge port as the center. The inner side of the support ears has a groove. The extrusion mold is cylindrical. The outer side of the bottom of the extrusion mold is provided with a lug that matches the groove on the support ear, so that the extrusion mold can be screwed into the groove of the support ear through the lug and detachably fixed to the inner side of the bottom wall of the vacuum chamber body.

[0015] Furthermore, the extrusion die is wrapped with a heating element on the outside, and the extrusion ratio is 8:1. Preferably, the vacuum cavity body has a cuboid structure.

[0016] The advantages and technical effects of this invention are as follows: 1. Achieved highly reliable dynamic sealing at high temperatures. To address the dynamic sealing challenges of large-size spindles (>φ200mm), an innovative multi-composite sealing ring and adjustable clamping structure are employed. Adjusting the screw allows for real-time compensation of seal wear, ensuring the system can maintain a stable high vacuum state (e.g., <10) over a long period. -(³ Pa), which fundamentally eliminates the oxidation and decomposition of materials at high temperatures.

[0017] 2. Utilize vertical layout to fundamentally improve product quality. The vertical structure aligns the direction of gravity with the extrusion axis. This completely eliminates the uneven gaps and unstable friction caused by the weight of horizontal equipment, resulting in more uniform material flow, effectively avoiding defects such as "extrusion tailing," and significantly reducing the risk of component segregation and contamination, thus ensuring the uniformity of product composition and microstructure.

[0018] 3. Achieve process optimization and stable production through high integration. This system integrates heating, extrusion, vacuuming, and mold fixing functions into a single high-vacuum chamber. It creates a uniform and stable high-temperature field (>400℃) and provides a platform for the coordinated control of key process parameters such as vacuum, temperature, and pressure, greatly improving process repeatability and product yield.

[0019] 4. Innovative mold separation mechanism improves efficiency and reliability A mold support lug is designed inside the cavity. It can reliably separate the mold from the product during the spindle return stroke, effectively solving the problem of mold sticking, protecting the mold and product shape, shortening the production cycle, and improving the automation and reliability of equipment operation.

[0020] 5. Possesses core capabilities for large-scale industrial production. The mold design supports the compression of over 7 kg of powder in a single batch, employing a high extrusion ratio of 8:1. This results in high single-batch output, significantly outperforming laboratory equipment in terms of production efficiency and substantially reducing unit costs, providing a reliable equipment foundation for the large-scale commercial production of bismuth telluride thermoelectric materials. Attached Figure Description Figure 1 This is a perspective view of the high-vacuum system of the vertical hot extrusion press for bismuth telluride materials according to the present invention.

[0021] Figure 2 This is a cross-sectional view of the high-vacuum system of the vertical hot extrusion press for bismuth telluride materials according to the present invention.

[0022] Figure 3 This is a top view of the high vacuum system of the vertical hot extrusion press for bismuth telluride materials according to the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] In the description of this invention, it should be noted that the terms "upper", "middle", "lower", "inner", "outer", "both sides", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the purpose of simplifying the description of this invention and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] like Figure 1-3 As shown, the vertical hot extrusion high vacuum system for bismuth telluride thermoelectric materials of the present invention includes a vertical vacuum chamber body 12. A cavity door 7 for installing and debugging internal system components is installed on the side wall of the vacuum chamber body 12. An electrical and gas connection port 3 connected to the inner cavity of the vacuum chamber body 12 is also opened on the side wall of the vacuum chamber body 12. An opening 13 for installing the extrusion shaft of the hot extrusion host is opened on the top wall of the vacuum chamber body 12. A dynamic sealing structure 6 is provided in the opening 13. A detachable extrusion mold 9 is installed on the inner side of the bottom wall of the vacuum chamber body 12. An outlet 1 for extruding the extruded material rod is provided on the outer side of the bottom wall of the vacuum chamber body 12, which communicates with the extrusion mold 9.

[0027] The cavity door 7 is a side-opening door, connected to the vacuum cavity body 12 by two hinges 5, and a sealing ring 4 is provided on the inner side of the cavity door 7.

[0028] A door handle 8 is provided on the outside of the cavity door 7.

[0029] The discharge port 1 is sealed by a vacuum blind flange.

[0030] The vacuum chamber body 12 is externally equipped with a mechanical pump and a molecular pump that are connected to the electrical and gas connection ports 3 for extracting gas from the vacuum chamber.

[0031] The lower outer side of the vacuum chamber body 12 is provided with a positioning ear 2, which is used to fix the vacuum chamber body on the support platform of the hot extrusion machine.

[0032] The diameter of the opening 13 is greater than 200mm, and the dynamic sealing structure 6 uses 3 sealing rings and 2 sealing gaskets.

[0033] The vacuum chamber body 12 has four support ears 10 for fixing the extrusion mold 9 on the inner side of its bottom wall. The support ears 10 are evenly arranged on the same circumference with the discharge port 1 as the center. The inner side of the support ears 10 has a groove. The extrusion mold 9 is cylindrical. The bottom outer side of the extrusion mold 9 has a protrusion 11 that matches the groove on the support ear 10, so that the extrusion mold 9 can be screwed into the groove of the support ear 10 through the protrusion 11 and detachably fixed to the inner side of the bottom wall of the vacuum chamber body 12.

[0034] The extrusion die 9 is wrapped with a heating element on the outside, and the extrusion ratio is 8:1. In this embodiment, the vacuum cavity body 12 has a cuboid structure.

[0035] Specifically, at outlet 1, the extruded material bar is extruded from this outlet. Positioning ear 2 uses four positioning studs to fix the vacuum chamber in the stage of the hot extruder, and determines the relative position between the two. The vacuum chamber has electrical and pneumatic connection ports 3 to the external environment, enabling the heating of the mold and the filling of the internal protective atmosphere during the operation of the hot extruder; it is also connected to external mechanical pumps and molecular pumps to achieve a high degree of vacuum.

[0036] The sealing ring 4, the hinge 5 connecting the vacuum chamber body and the vacuum chamber door 7, and the door handle 8 of the vacuum chamber door together achieve a sealed connection with the vacuum chamber body.

[0037] Dynamic seal structure 6, with a relatively large diameter, houses the main shaft of the hot extrusion machine, which has a diameter exceeding 200mm. This dynamic seal is the largest leakage point in the overall sealing structure. To ensure sufficient vacuum, three O-rings and two gaskets are designed and installed here, ultimately achieving a strong seal.

[0038] The extrusion die 9 with a vacuum chamber structure is wrapped with a heating element on the outside of the die during actual operation, providing a temperature of over 400°C, which can be maintained for a long time. The cavity inside the die is filled with bismuth telluride powder, which can press more than 7 kg of powder at a time with an extrusion ratio of 8:1. The die adopts a split design to enhance structural stability.

[0039] 10 are the support lugs inside the vacuum chamber, and there are four of them. When the extrusion spindle is pulled out of the mold, 10 will hold the extrusion mold, causing the extrusion spindle to separate from the mold.

[0040] To further understand the invention's content, features, and effects, the following embodiments are provided and described in detail below: In this embodiment, the main structure is a vacuum chamber and the positioning between the vacuum chamber body and the extrusion mold. A mechanical pump and a molecular pump are installed outside the vacuum chamber body for extracting gas from the vacuum chamber.

[0041] The vacuum chamber body 12 is equipped with a chamber door 7 with a relatively large opening. In actual operation, this chamber door is used for the installation and debugging of relevant components inside the system; it is also used to place bismuth telluride material when extruding materials. The chamber door 7 is sealed by a sealing ring 4, two hinges 5, and a door handle 8.

[0042] To achieve a high vacuum level, the vacuum chamber adopts an integrated design, with the only opening in the overall structure at the top where it contacts the extrusion shaft. This extrusion shaft has a large diameter (greater than 200mm), and a dynamic sealing structure is used here, employing an alternating sealing structure of three sealing rings and two sealing gaskets. The actual operating temperature here is below 100℃, and this sealing structure meets design specifications. The screw structure also facilitates the maintenance and replacement of consumable seals.

[0043] Internally, the temperature sensors, heating circuits, and protective gas filling ports are all connected via standard vacuum connectors to ensure a tight seal. The bottom outlet 1 is sealed with a vacuum blind flange for easy disassembly and assembly.

[0044] The extrusion die 9 is designed with an extrusion ratio of 8:1. The die is a split design to enhance structural stability and can hold over 7 kg of bismuth telluride powder at a time. The extrusion die 9 is screwed into the groove of the support ear 10 via the lug 11. The extrusion die and the vacuum chamber are separately positioned, with no fixed connection, reducing stress caused by relative positional misalignment during extrusion and extending die life. The lug 11 and support ear 10 provide constraint when the extrusion rod is pulled out of the die.

[0045] During the overall installation, apply a layer of sealing grease to the hot extrusion spindle. The moving hot extrusion spindle will evenly spread the sealing grease into the sealing structure. For the connection of other vacuum standard parts, apply sealing grease to the sealing ring as well.

[0046] 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, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A vertical hot extrusion high vacuum system for bismuth telluride thermoelectric material, characterized by, The utility model relates to a vertical vacuum cavity body (12) is provided with cavity door (7) for installing and debugging the internal components of system on the side wall of vacuum cavity body (12), and the side wall of vacuum cavity body (12) is also provided with electricity, gas connecting port (3) communicated with the inner cavity of vacuum cavity body (12), the top wall of vacuum cavity body (12) is provided with the opening (13) for installing the extrusion shaft of hot extrusion host, the opening (13) is provided with dynamic sealing structure (6), the inner side of the bottom wall of vacuum cavity body (12) is provided with detachable extrusion die (9), and the outer side of the bottom wall of vacuum cavity body (12) is provided with the discharge port (1) communicated with extrusion die (9) and extruding the material bar of extrusion forming.

2. The vertical hot extrusion high vacuum system for bismuth telluride thermoelectric material according to claim 1, wherein The cavity door (7) is a side opening door, which is connected to the vacuum cavity body (12) through two hinges (5), and the inner side of the cavity door (7) is provided with a sealing ring (4).

3. The vertical hot extrusion high vacuum system for bismuth telluride thermoelectric material according to claim 2, wherein The outer side of the cavity door (7) is provided with a door handle (8).

4. The vertical hot extrusion high vacuum system for bismuth telluride thermoelectric material according to claim 1, wherein The discharge port (1) is blocked by a vacuum blind plate.

5. The vertical hot extrusion high vacuum system for bismuth telluride thermoelectric material according to claim 1, wherein The vacuum cavity body (12) is provided with a mechanical pump and a molecular pump communicated with the electricity and gas connecting port (3) outside, which is used for extracting gas in the vacuum cavity chamber.

6. The vertical hot extrusion high vacuum system for bismuth telluride thermoelectric material according to claim 1, wherein The lower part of the outer side of the vacuum cavity body (12) is provided with a positioning lug (2) for fixing the vacuum cavity body on the material supporting table of the hot extrusion machine.

7. The vertical hot extrusion high vacuum system for bismuth telluride thermoelectric material according to claim 1, wherein The diameter of the opening (13) is more than 200 mm, and the dynamic sealing structure (6) is provided with three sealing rings and two sealing pads.

8. The vertical hot extrusion high vacuum system for bismuth telluride thermoelectric material according to claim 1, wherein, The inner side of the bottom wall of the vacuum cavity body (12) is provided with four supporting lugs (10) for fixing the extrusion die (9), which are uniformly and alternately arranged on the same circle with the discharge port (1) as the center, the inner side of the supporting lug (10) is provided with a groove, the extrusion die (9) is a cylindrical shape, and the outer side of the bottom of the extrusion die (9) is provided with a lug (11) matched with the groove of the supporting lug (10), so that the extrusion die (9) is rotatably fixed to the inner side of the bottom wall of the vacuum cavity body (12) through the lug (11) and the groove of the supporting lug (10).

9. The vertical hot extrusion high vacuum system for bismuth telluride thermoelectric material according to claim 1, wherein The outer side of the extrusion die (9) is wrapped with a heating body, and the extrusion ratio is 8:

1.

10. The vertical hot extrusion high vacuum system for bismuth telluride thermoelectric material according to any one of claims 1 to 9, characterized in that, The vacuum cavity body (12) is a rectangular parallelepiped structure.

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