A thermostatic hot pressing device for magnet processing

Abstract

This invention discloses a constant-temperature hot pressing device for magnet processing, relating to the field of magnet processing. It includes a support base and a lower mold fixed inside the support base, with an upper mold positioned directly above the lower mold. A stress support mechanism is provided within a stress support cylinder. The heating assembly includes an upper heating element disposed within a flow channel inside the upper mold and a lower heating element disposed within a flow channel inside the lower mold. The internal flow channel of the lower mold is connected to the inner cavity of a sealed oil tank via a recovery pipe. This constant-temperature hot pressing device for magnet processing, through the dual-zone layout of the upper and lower heating elements, effectively mitigates the rigid impact and stress concentration during the mold closing process, avoiding mold deformation and magnet forming defects. Simultaneously, by employing a sealed circulation oil circuit structure, it significantly improves the stability of the hot pressing process, substantially increases the batch performance consistency and production yield of magnets, and extends the service life of the mold.

Description

Technical Field

[0001] This invention relates to the field of magnet processing technology, specifically a constant temperature hot pressing device for magnet processing. Background Technology

[0002] Rare earth permanent magnet materials are core functional components in new energy vehicle drive motors, industrial servo systems, wind power generation, and high-end precision electronic equipment. Among them, hot pressing is the core technology for preparing high-density, fine-grained, and highly coercive nanocrystalline rare earth permanent magnets. The hot pressing process for rare earth permanent magnet powder has an extremely narrow window, typically requiring pressing within a precise temperature range of 650℃-730℃. Poor temperature uniformity and large fluctuations during the hot pressing process will directly lead to insufficient density, decreased remanence, abnormal grain coarsening, and significant attenuation of coercivity in the finished magnet. At the same time, rigid impact during mold closing, thermal stress concentration, and asynchronous heating and pressing actions during the hot pressing process can also cause mold deformation, magnet forming defects, poor batch performance consistency, and low yield, among other industry pain points.

[0003] Currently, there are publicly available technologies for optimizing magnet hot pressing devices. Existing technology 1, Chinese utility model patent application number CN201420453521.8, filed on August 12, 2014, discloses a magnet hot pressing device. This device uses a linear drive mechanism to drive a push rod to move the billet between a preheating device and a die, achieving automatic feeding of the magnet billet and reducing manual operation intensity. Simultaneously, the splicing structure between the top surface of the lower heater and the bottom surface of the preheating device outlet avoids collision damage during billet transfer.

[0004] Prior art 2, Chinese utility model patent application number CN201420453652.6, application date August 12, 2014, discloses a sling-type magnetic hot pressing device. This device adopts a flexible connection structure between the upper heater and the upper oil cylinder, replacing the traditional rigid connection, realizing soft contact between the upper and lower heaters, alleviating the rigid impact during the mold closing process, and extending the service life of the heater.

[0005] In the aforementioned existing technologies, efforts are usually made to independently optimize the heating system or the buffer system. For example, when using a wrap-around flow channel to improve temperature uniformity, the huge rigid impact at the moment of mold closing is often ignored, which may cause micro-deformation of the flow channel or failure of the seal, thus affecting the temperature control accuracy. When using a spring to buffer the impact of mold closing, the timing of the flow of the heating medium cannot be controlled synchronously, resulting in asynchronous heating and pressing actions.

[0006] Therefore, we propose a constant-temperature hot pressing device for magnet processing to solve the problems mentioned above. Summary of the Invention

[0007] The purpose of this invention is to provide a constant temperature hot pressing device for magnet processing, in order to solve the problem mentioned in the background art that the current constant temperature hot pressing devices on the market often ignore the huge rigid impact at the moment of mold closing, which may cause micro-deformation of the flow channel or failure of the seal, thus affecting the temperature control accuracy, when using a spring to buffer the impact of mold closing.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a constant temperature hot pressing device for magnet processing, comprising a support base and a lower mold fixed inside the support base, an upper mold disposed directly above the lower mold, a drive mechanism connected to the upper mold on the support base, heating components on the lower mold and the upper mold, the drive mechanism including a drive motor fixedly mounted on the top of a sealed oil tank, a power piston assembly disposed inside the sealed oil tank and drivenly connected to the output end of the drive motor, the output end of a hydraulic push rod fixedly connected to the center of the top surface of the upper mold, the oil outlet of the sealed oil tank communicating with the oil inlet chamber of the hydraulic push rod via a delivery hose, and the delivery hose communicating with the oil outlet of the hydraulic push rod via a delivery hose. The three-way valve is connected to the internal flow channel of the upper mold; the lower edge of the upper mold is provided with several docking parts that communicate with the internal flow channel; the lower mold is provided with stress support cylinders that correspond one-to-one with the docking parts and are coaxially arranged; the top of the stress support cylinder is provided with a conveying connection pipe; the stress support cylinder is provided with a stress support mechanism; the two ends of the stress support mechanism are fixedly connected to the lower mold; the side wall of the stress support cylinder is provided with an oil outlet mechanism that communicates with the internal flow channel of the lower mold; the heating assembly includes an upper heating element disposed in the internal flow channel of the upper mold and a lower heating element disposed in the internal flow channel of the lower mold; the internal flow channel of the lower mold is connected to the inner cavity of the sealed oil tank through a recovery pipe.

[0009] Preferably, the lower mold has a forming cavity in the central area, and a fitting groove is formed circumferentially on the outer side of the forming cavity. The stress support cylinders are arranged at equal intervals along the circumference of the fitting groove, and the bottom of the forming cavity is fixedly connected to the inner wall of the lower mold through several support protrusions.

[0010] Preferably, the power piston assembly includes a threaded rod and an oil tank piston disc. The top end of the threaded rod is coaxially and fixedly connected to the output end of the drive motor, and the bottom end of the threaded rod extends into the interior of the sealed oil tank and is rotatably connected to the bottom of the sealed oil tank. The oil tank piston disc is threaded onto the outside of the threaded rod, and the outer wall of the oil tank piston disc is in a sealing sliding fit with the inner wall of the sealed oil tank. A sealing element is provided at the connection between the oil tank piston disc and the threaded rod.

[0011] Preferably, the mating part is a mating insert sleeve embedded in the end of the constant temperature flow channel inside the upper mold. The mating insert sleeve is composed of a mating tube, a fitting pad, and a one-way oil spray nozzle. The top end of the mating tube is connected to the internal constant temperature flow channel of the upper mold, and the bottom end of the mating tube extends to the lower surface of the upper mold. The fitting pad is circumferentially fixed to the outside of the bottom end of the mating tube. The one-way oil spray nozzle is opened at the center of the bottom end of the mating tube and is coaxially arranged with the conveying connecting pipe. In the mold closing state, the bottom surface of the fitting pad is sealed and fitted with the top end face of the conveying connecting pipe.

[0012] Preferably, a sealing strip is circumferentially fixed to the lower surface edge of the upper mold. In the mold-closed state, the sealing strip is sealed and adhered to the outer top of the fitting groove. Adjacent stress support cylinders are interconnected through connecting branch pipes. The two ends of the stress support mechanism are respectively fixed to the inner walls of the opposite sides of the fitting groove.

[0013] Preferably, the stress support mechanism includes two sets of pipe piston discs, a return spring, and two support crossbars. The two sets of pipe piston discs are symmetrically and slidably disposed at both ends inside the stress support cylinder. The two ends of the return spring are fixedly connected to the opposite end faces of the two sets of pipe piston discs, respectively. The inner ends of the two support crossbars are fixedly connected to the opposite end faces of the two sets of pipe piston discs, respectively. The outer ends of the two support crossbars are fixedly connected to the corresponding inner walls of the fitting grooves, respectively.

[0014] Preferably, multiple sets of stress support mechanisms are evenly arranged at equal intervals along the circumference of the bonding groove, and a heat conduction channel is provided between the inner side of the bonding groove and the bottom outer wall of the molding cavity. The heat conduction channel is interconnected with the constant temperature flow channel formed by the upper mold and the support protrusion.

[0015] Preferably, the oil outlet mechanism includes a tapered hole inside the conveying connecting pipe, and the bottom end of the tapered hole is connected to the inside of the stress support cylinder. The tapered cylinder is sealed and fitted to the inside of the tapered hole. The top end of the connecting spring is fixedly connected to the bottom end of the tapered cylinder, and the bottom end of the connecting spring is fixedly connected to the inner wall of the support crossbar. The oil outlet is opened on the outer side wall of the support crossbar, and the oil outlet is connected to the internal through hole of the support crossbar.

[0016] Preferably, the support crossbar has an axially extending through hole inside, the inner end of the through hole is connected to the inside of the stress support cylinder, the outer end of the through hole is connected to the oil outlet, and the outlet end of the oil outlet is connected to the internal constant temperature flow channel of the lower mold.

[0017] Preferably, the elastic coefficient of the connecting spring is greater than that of the return spring, and the conical cylinder forms an axial elastic sliding structure in the conical hole through the connecting spring; the lower mold has a conical guide channel at one end of the internal constant temperature flow channel near the recovery pipe, the small end of the conical guide channel is connected to the inlet end of the recovery pipe, and the outlet end of the recovery pipe is connected to the upper side wall of the sealing oil tank.

[0018] Compared with existing technologies, the beneficial effects of this invention are as follows: This constant-temperature hot pressing device for magnet processing, through the dual-zone layout of upper and lower heating elements and the all-area heat conduction structure of circulating hydraulic oil, eliminates the temperature difference between the center and edge of the forming mold cavity, controlling the temperature fluctuation during the hot pressing process to a very small range. This solves the problems of insufficient magnet density, grain coarsening, and coercivity decay caused by uneven temperature in traditional devices. Through the cooperation of the stress support mechanism and the mold closing guide structure, the rigid impact and extrusion stress concentration during the mold closing process are effectively mitigated, avoiding mold deformation and magnet forming defects. At the same time, through the cooperation of the sealed circulation oil circuit structure, the stability of the hot pressing process is greatly improved, significantly increasing the batch performance consistency and production yield of magnets, while extending the service life of the mold. Specific details are as follows: 1. By using a surround layout of upper and lower dual heating elements, combined with circulating constant-temperature hydraulic oil as the heat transfer medium, uniform heating is achieved throughout the molding cavity. This strictly controls the temperature deviation during the hot pressing process within the process requirements of rare-earth permanent magnets, avoiding the problems of insufficient magnet density and decreased remanence caused by low temperatures in traditional devices, as well as grain coarsening and coercivity attenuation caused by high temperatures. At the same time, the sealed circulation oil circuit structure reduces heat loss and ensures temperature stability during long-term hot pressing, meeting the preparation requirements of high-end rare-earth permanent magnets. 2. The stress support mechanism built into the stress support cylinder can effectively absorb the rigid impact and extrusion stress generated during the mold closing process, avoiding deformation and damage of the mold under long-term high-pressure conditions, and significantly extending the service life of the mold; the coaxial drive structure of the guide rod and hydraulic push rod ensures the alignment accuracy of the upper and lower molds during mold closing, avoiding deviations in magnet forming; at the same time, the integrated oil circuit circulation and docking sealing structure realizes the functional reuse of hydraulic drive and heat conduction circulation, adapting to the needs of automated continuous production and effectively improving the production efficiency of magnet hot pressing; Furthermore, a pressure threshold switch is constructed by using the difference in elastic coefficients between the reset spring and the connecting spring through the stress support mechanism built into the stress support cylinder; this not only effectively absorbs the rigid impact and extrusion stress during the mold closing process and avoids mold deformation, but more importantly, it realizes adaptive timing control of buffering first and then oiling; that is, the heat source disturbance is cut off when the mold is not stable, and the full-area heating cycle is started only after the mold is stable. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the main structure of the present invention; Figure 2 This is a schematic diagram of the rear view structure of the present invention; Figure 3 This is a schematic diagram of the main cross-sectional structure of the sealed oil tank of the present invention; Figure 4 This is a schematic diagram of a partial cross-sectional structure of the mold of the present invention; Figure 5 This is a partial bottom view of the docking and embedding sleeve structure of the present invention; Figure 6 This is a top view of the mold structure of the present invention; Figure 7 This is a schematic diagram of the main cross-sectional structure of the mold of the present invention; Figure 8 This is a schematic diagram of the main structure of the stress support cylinder of the present invention; Figure 9 This is a schematic diagram of the main cross-sectional structure of the stress support cylinder of the present invention; Figure 10 This is a schematic diagram of the main cross-sectional structure of the supporting crossbar of the present invention.

[0020] In the diagram: 1. Support base; 2. Lower mold; 201. Molding cavity; 202. Fitting groove; 203. Supporting protrusion; 3. Upper mold; 301. Upper heating element; 4. Drive motor; 5. Sealing oil tank; 6. Threaded rod; 7. Oil tank piston plate; 8. Delivery hose; 9. Hydraulic push rod; 10. Guide rod; 11. Butt fitting sleeve; 1101. Connecting pipe; 1102. Fitting pad; 1103. One-way oil spray nozzle; 12. Lower heating element; 13. Stress support cylinder; 1301. Connecting branch pipe; 14. Delivery connecting pipe; 15. Return spring; 16. Pipe piston plate; 17. Support crossbar; 18. Conical cylinder; 19. Conical hole; 20. Connecting spring; 21. Oil outlet channel; 22. Recovery pipe. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figures 1-10 The present invention provides the following technical solution: a constant temperature hot pressing device for magnet processing.

[0023] Example 1: To address the issues of current market-available constant-temperature hot pressing devices lacking a mold-closing stress relief structure, resulting in mold wear due to rigid impacts during the mold-closing process, failing to meet long-term large-scale production requirements, exhibiting large batch-to-batch performance deviations in magnets, and being unsuitable for the fabrication requirements of high-end rare-earth permanent magnets, please refer to the attached... Figure 2 - Appendix Figure 10A constant-temperature hot pressing device for magnet processing includes a support base 1 and a lower mold 2 fixed inside the support base 1. An upper mold 3 is positioned directly above the lower mold 2. The support base 1 is equipped with a drive mechanism connected to the upper mold 3. Heating components are provided on the lower mold 2 and the upper mold 3. The drive mechanism includes a drive motor 4 fixedly mounted on the top of a sealed oil tank 5. A power piston assembly is located inside the sealed oil tank 5 and is connected to the output end of the drive motor 4. The output end of a hydraulic push rod 9 is fixedly connected to the center of the top surface of the upper mold 3. The oil outlet of the sealed oil tank 5 is connected to the oil inlet chamber of the hydraulic push rod 9 via a delivery hose 8. The delivery hose 8 is connected to the internal flow channel of the upper mold 3 via a three-way valve. The lower edge of the upper mold 3... The lower mold 2 has several docking parts that communicate with the internal flow channels. The lower mold 2 contains stress support cylinders 13 that correspond one-to-one with the docking parts and are coaxially arranged. A conveying connection pipe 14 is provided at the top of the stress support cylinder 13. A stress support mechanism is provided inside the stress support cylinder 13, with both ends of the stress support mechanism fixedly connected to the lower mold 2. A forming cavity 201 is opened in the central area of ​​the lower mold 2. A fitting groove 202 is circumferentially opened on the outer side of the forming cavity 201 in the lower mold 2. The stress support cylinders 13 are arranged at equal intervals along the circumference of the fitting groove 202. The bottom of the forming cavity 201 is fixedly connected to the inner wall of the lower mold 2 through several supporting protrusions 203. The power piston assembly includes a threaded rod 6 and an oil tank piston disc 7. The top end of the threaded rod 6 is connected to... The output end of the drive motor 4 is coaxially fixedly connected. The bottom end of the threaded rod 6 extends into the interior of the sealing oil tank 5 and is rotatably connected to the bottom of the sealing oil tank 5. The oil tank piston disc 7 is threadedly sleeved on the outside of the threaded rod 6. The outer wall of the oil tank piston disc 7 is in sealing sliding contact with the inner wall of the sealing oil tank 5. A seal is provided at the connection between the oil tank piston disc 7 and the threaded rod 6. The docking part is a docking insert 11 embedded in the end of the constant temperature flow channel inside the upper mold 3. The docking insert 11 is composed of a connecting pipe 1101, a soft pad 1102, and a one-way oil spray nozzle 1103. The top end of the connecting pipe 1101 communicates with the internal constant temperature flow channel of the upper mold 3. The bottom end of the connecting pipe 1101 extends to the lower surface of the upper mold 3. The soft pad 1102... 02 is circumferentially fixed to the outer side of the bottom end of the connecting pipe 1101. The one-way oil spray port 1103 is opened at the center of the bottom end of the connecting pipe 1101, and the one-way oil spray port 1103 is coaxially arranged with the conveying connecting pipe 14. In the mold closing state, the bottom surface of the soft pad 1102 is sealed and fitted with the top end face of the conveying connecting pipe 14. The corners of the top of the upper mold 3 are connected to the inner wall of the support base 1 through the guide rod 10. The lower surface edge of the upper mold 3 is circumferentially fixed with a sealing strip. In the mold closing state, the sealing strip is sealed and fitted to the outer side of the top of the fitting groove 202. The two adjacent stress support cylinders 13 are connected to each other through the connecting branch pipe 1301. The two ends of the stress support mechanism are respectively fixed on the inner walls of the opposite sides of the fitting groove 202.The stress support mechanism includes two sets of pipe piston discs 16, a return spring 15, and two support crossbars 17. The two sets of pipe piston discs 16 are symmetrically and slidably disposed at both ends inside the stress support cylinder 13. The two ends of the return spring 15 are fixedly connected to the opposite end faces of the two sets of pipe piston discs 16, respectively. The inner ends of the two support crossbars 17 are fixedly connected to the opposite end faces of the two sets of pipe piston discs 16, respectively, and the outer ends of the two support crossbars 17 are fixedly connected to the corresponding inner walls of the bonding groove 202, respectively. Multiple sets of stress support mechanisms are evenly and uniformly arranged at equal intervals along the circumference of the bonding groove 202. A heat conduction channel is provided between the inner side of the bonding groove 202 and the bottom outer wall of the molding cavity 201. The heat conduction channel is interconnected with the constant temperature flow channel formed by the upper mold 3 and the support protrusion 203.

[0024] The rare earth permanent magnet powder to be hot-pressed is quantitatively filled into the forming cavity 201 in the central area of ​​the lower mold 2, and the surface of the magnetic powder is leveled. The device control system is started to complete the power-on self-test of the drive motor 4 and the heating components, confirming that the three-way valve is in the initial conduction state, and the sealed oil tank 5 is filled with heat-conducting hydraulic oil that meets the working conditions. The device is in the state of waiting to close the mold. The bottom of the forming cavity 201 is fixed to the inner wall of the lower mold 2 by multiple sets of support protrusions 203, providing rigid support for the bottom of the mold cavity and avoiding deformation of the bottom of the mold cavity during subsequent hot pressing. The control system sends a mold closing command, the drive motor 4 starts in the forward direction, and its output end drives the coaxially fixed threaded rod 6 to rotate synchronously in the sealed oil tank 5. The piston disc 7 of the oil tank, threaded onto the outside of the threaded rod 6, slides vertically downward along the inner wall of the sealed oil tank 5 under the action of the threaded transmission, squeezing the hydraulic oil in the lower cavity of the sealed oil tank 5 to form a stable oil pressure; the pressurized hydraulic oil enters the delivery hose 8 through the oil outlet of the sealed oil tank 5, and is divided into two paths through the three-way valve: the first path of hydraulic oil enters the oil inlet chamber of the hydraulic push rod 9, pushing the push rod end of the hydraulic push rod 9 to extend vertically downward, driving the upper mold 3, which is fixedly connected to the push rod end, to descend smoothly in the vertical direction, providing a stable driving force for mold closing; the second path of hydraulic oil simultaneously enters the internal flow channel of the upper mold 3, reserving a medium channel for the subsequent heat conduction circulation after mold closing; the upper mold 3 descends... When the mold reaches the mold closing station, multiple sets of mating inserts 11 arranged circumferentially on its lower edge correspond one-to-one with the stress support cylinders 13 arranged equidistantly on the inner circumference of the fitting groove 202 of the lower mold 2, and are coaxially aligned; the one-way oil spray port 1103 at the bottom of the connecting pipe 1101 is coaxially aligned with the conveying connecting pipe 14 at the top of the stress support cylinder 13, and the fitting soft pad 1102 on the outer side of the bottom end of the connecting pipe 1101 is tightly pressed against the top end face of the conveying connecting pipe 14 to form an end face sealing structure, preventing leakage during subsequent hydraulic oil delivery; at the same time, the sealing strip fixed circumferentially on the lower surface edge of the upper mold 3 is tightly fitted against the outer top end of the fitting groove 202 of the lower mold 2, forming a sealing structure after mold closing. The outer sealing structure completes the mold closing action, so that the upper mold 3 and the lower mold 2 enclose a closed hot pressing forming space; through the matching structure of the docking insert sleeve 11 and the conveying connecting pipe 14, the pressure is synchronously transmitted to multiple sets of circumferentially evenly arranged stress support cylinders 13; the stress support mechanism in the stress support cylinder 13 bears the pressure, and the two sets of symmetrically arranged pipe piston discs 16 are subjected to pressure and slide relatively sealed along the inner wall of the stress support cylinder 13, synchronously compressing the return spring 15 between the two sets of pipe piston discs 16. The return spring 15 absorbs the energy of the rigid impact of mold closing through elastic deformation, realizes the relief of mold closing stress, and avoids the rigid impact directly acting on the mold body and causing mold wear.

[0025] Two support crossbars 17, fixedly connected to the pipe piston disc 16, uniformly transmit the buffered mold closing pressure to the inner walls of opposite sides of the fitting groove 202. Multiple sets of circumferentially arranged stress support mechanisms work together to ensure that the mold closing pressure is evenly distributed along the circumference of the forming mold cavity 201, eliminating the stress concentration problem during the mold closing process. Adjacent stress support cylinders 13 are interconnected through connecting branch pipes 1301 to ensure that the oil pressure inside each set of stress support cylinders 13 remains consistent, further ensuring the uniformity of circumferential load, avoiding local overload deformation of the mold, and ensuring the dimensional accuracy of the forming mold cavity 201 is stable during hot pressing. After the mold closing stress stabilizes, the device enters the hot pressing and pressure holding process. The heat conduction channel between the inner side of the fitting groove 202 and the outer wall of the bottom end of the forming mold cavity 201 is interconnected with the constant temperature flow channel formed by the upper mold 3 and the support protrusion 203, uniformly transferring the heat of the flow channel inside the upper mold 3 to the forming mold cavity 201. With the help of the heating components, the magnetic powder can be formed by constant temperature hot pressing.

[0026] Example 2: To address the issues of current market-available constant-temperature hot pressing devices employing single-end preheating and single-zone heating structures, which fail to achieve uniform temperature control throughout the molding cavity 201, resulting in significant temperature differences between the cavity center and edges, and thus failing to guarantee the constant temperature requirements of the magnet hot pressing process, leading to poor consistency in the performance of the finished magnets, please refer to the attached... Figure 3 - Appendix Figure 7 The stress support cylinder 13 has an oil outlet mechanism on its side wall that communicates with the internal flow channel of the lower mold 2; the heating assembly includes an upper heating element 301 disposed in the internal flow channel of the upper mold 3 and a lower heating element 12 disposed in the internal flow channel of the lower mold 2; the internal flow channel of the lower mold 2 is connected to the inner cavity of the sealed oil tank 5 through a recovery pipe 22; the oil outlet mechanism includes a tapered hole 19 opened inside the conveying connecting pipe 14, and the bottom end of the tapered hole 19 communicates with the inside of the stress support cylinder 13, the tapered cylinder 18 is sealed and fitted inside the tapered hole 19, the top end of the connecting spring 20 is fixedly connected to the bottom end of the tapered cylinder 18, the bottom end of the connecting spring 20 is fixedly connected to the inner wall of the support crossbar 17, and the oil outlet channel 21 is opened in the support crossbar 17. On the outer sidewall, the oil outlet channel 21 is connected to the internal through hole of the support crossbar 17; the support crossbar 17 has an axially extending through hole, the inner end of which is connected to the inside of the stress support cylinder 13, and the outer end of which is connected to the oil outlet channel 21. The outlet end of the oil outlet channel 21 is connected to the internal constant temperature flow channel of the lower mold 2; the elastic coefficient of the connecting spring 20 is greater than the elastic coefficient of the return spring 15, and the conical cylinder 18 forms an axial elastic sliding structure in the conical hole 19 through the connecting spring 20; the internal constant temperature flow channel of the lower mold 2 has a conical guide channel at one end near the recovery pipe 22, the small end of the conical guide channel is connected to the inlet end of the recovery pipe 22, and the outlet end of the recovery pipe 22 is connected to the upper sidewall of the sealing oil tank 5.

[0027] During the hot pressing preparation stage, the upper heating element 301 and the lower heating element 12 are started simultaneously to precisely heat the hydraulic oil in the internal flow channels of the upper mold 2 and the lower mold 3 in a dual-zone manner, stabilizing the oil temperature within the process range of rare earth permanent magnet hot pressing. Because the elastic coefficient of the connecting spring 20 is greater than that of the return spring 15, stress relief is prioritized during mold closing. After the mold is closed, the oil pressure overcomes the elastic force of the connecting spring 20 to open the conical cylinder 18, opening the oil circuit and achieving precise synchronization between the pressing action and the constant temperature heating. The constant temperature hydraulic oil in the upper mold 3 enters the stress support cylinder 13 through the docking structure, and then... The oil flows into the internal flow channel of the lower mold 2 through the internal through hole of the support crossbar 17 and the oil outlet channel 21. The heat is evenly transferred to the entire area of ​​the forming mold cavity 201 through the heat conduction channel, eliminating the temperature difference between the center and the edge of the mold cavity. The hydraulic oil flows through the conical guide channel at the end of the flow channel of the lower mold 2 and is recovered by the negative pressure in the sealed oil tank 5. The hydraulic oil flows back to the sealed oil tank 5 through the recovery pipe 22 through the conical guide channel, forming a fully enclosed constant temperature oil circuit circulation to ensure the temperature stability of long-term hot pressing. After the hot pressing is completed, the oil pressure in the oil circuit drops, and the connecting spring 20 drives the conical cylinder 18 to reset and seal the circuit.

[0028] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A constant temperature hot pressing device for magnet processing, comprising a support base (1) and a lower mold (2) fixed inside the support base (1), wherein the lower mold (2) is provided with a forming cavity (201), a fitting groove (202) and a heat conduction channel connecting the outer wall of the forming cavity (201) and the inner side of the fitting groove (202); an upper mold (3) is disposed directly above the lower mold (2), wherein the upper mold (3) is provided with an internal flow channel and an upper heating element (301), characterized in that: The drive mechanism includes a sealed oil tank (5), a drive motor (4), a threaded rod (6), an oil tank piston plate (7), a hydraulic push rod (9), and a delivery hose (8), wherein the delivery hose (8) connects the sealed oil tank (5) and the internal flow channel of the upper mold (3); the stress support mechanism and the oil circuit switching mechanism include a docking insert sleeve (11) located at the lower edge of the upper mold (3) and a stress support cylinder (13) located in the lower mold (2) and coaxially docked with the docking insert sleeve (11); the stress support cylinder (13) is provided with a stress support mechanism, which includes a return spring (15) and a connecting spring (2). 0) and conical cylinder (18); the elastic coefficient of the connecting spring (20) is greater than that of the return spring (15), and a pressure threshold is built during the mold closing process, so that the return spring (15) is compressed to absorb rigid impact in the early stage of mold closing, and the connecting spring (20) is compressed to drive the conical cylinder (18) to open the oil circuit after the mold is closed; the stress support cylinder (13) is fixedly connected to the inner wall of the lower mold (2) through the support crossbar (17), and the support crossbar (17) has a through hole that connects the stress support cylinder (13) and the heat conduction channel, so as to form a constant temperature flow field that wraps the molding cavity (201) after the oil circuit is opened.

2. The constant temperature hot pressing device for magnet processing according to claim 1, characterized in that: The top of the stress support cylinder (13) is provided with a conveying connection pipe (14). The docking insert (11) includes a docking pipe (1101), a fitting soft pad (1102), and a one-way oil spray nozzle (1103). In the mold closing state, the fitting soft pad (1102) is sealed and fitted to the top end face of the conveying connection pipe (14), and the one-way oil spray nozzle (1103) is coaxially docked with the conveying connection pipe (14) to introduce the heat-conducting hydraulic oil in the flow channel of the upper mold (3) into the stress support cylinder (13).

3. The isothermal hot pressing device for magnet processing according to claim 1, characterized in that: The stress support mechanism also includes two sets of pipe piston discs (16), the reset spring (15) is connected between the two sets of pipe piston discs (16), and the support crossbar (17) is fixed between the pipe piston disc (16) and the inner wall of the lower mold (2); the support crossbar (17) also serves as a stress transmission component and a heat transfer oil transmission channel, and its outer end side wall is provided with an oil outlet channel (21) communicating with the through hole, and the oil outlet channel (21) is connected to the constant temperature flow channel inside the lower mold (2).

4. The constant temperature hot pressing device for magnet processing according to claim 2, characterized in that: The conveying connecting pipe (14) has a tapered hole (19) inside, and the tapered cylinder (18) is sealed and fitted to the inside of the tapered hole (19). The connecting spring (20) is connected between the tapered cylinder (18) and the inner wall of the support crossbar (17). The tapered cylinder (18) is configured to undergo axial displacement when the mold closing pressure reaches the pressure threshold, and to conduct the oil passage between the stress support cylinder (13) and the internal through hole of the support crossbar (17).

5. A constant-temperature hot pressing device for magnet processing according to claim 1, characterized in that: The internal constant temperature flow channel of the lower mold (2) is connected to the inner cavity of the sealed oil tank (5) through the recovery pipe (22). The inlet end of the recovery pipe (22) is provided with a conical guide channel. The small end of the conical guide channel is connected to the recovery pipe (22) to collect the heat-conducting hydraulic oil and form a fully enclosed circulation loop.

6. The constant temperature hot pressing device for magnet processing according to claim 1, characterized in that: The bottom of the forming cavity (201) is fixedly connected to the inner wall of the lower mold (2) by a number of supporting protrusions (203); the heat conduction channel is formed by the upper mold (3), supporting protrusions (203) and lower mold (2), and two adjacent stress support cylinders (13) are connected to each other by connecting branch pipes (1301) to maintain circumferential oil pressure balance.

7. A constant-temperature hot pressing device for magnet processing according to claim 6, characterized in that: The top four corners of the upper mold (3) are slidably connected to the inner wall of the support base (1) through the guide rod (10). A sealing strip is fixed around the lower surface edge of the upper mold (3). In the mold-closed state, the sealing strip is sealed and attached to the outer side of the top of the fitting groove (202), and together with the mating insert sleeve (11), it forms a mold-closed sealing interface.

8. A constant-temperature hot pressing device for magnet processing according to claim 6, characterized in that: The difference in elastic coefficients between the reset spring (15) and the connecting spring (20) is configured to match the buffer stroke of the stress support mechanism with the timing of oil circuit conduction, so that the full-range heating cycle is triggered only after the peak of mold closing impact.

9. A constant-temperature hot pressing device for magnet processing according to claim 8, characterized in that: The lower mold (2) is provided with a lower heating element (12) in the internal flow channel. The upper heating element (301) and the lower heating element (12) are configured to heat the heat-conducting hydraulic oil flowing through the flow channels of the upper mold (3) and the lower mold (2) in a dual-zone manner to maintain the temperature uniformity of the entire molding cavity (201).

10. A constant-temperature hot pressing device for magnet processing according to claim 8, characterized in that: The stress support cylinder (13) is arranged at equal intervals along the circumference of the fitting groove (202). The two ends of the support crossbar (17) are respectively fixed to the inner walls of the opposite sides of the fitting groove (202) so as to uniformly transmit the buffered mold closing pressure to the lower mold (2) and serve as a transmission channel for the heat-conducting hydraulic oil to flow to the whole domain flow channel.

Images