Sealing magnetic field pressing machine

Abstract

The invention discloses a sealed magnetic field pressing machine which comprises a material storage device, a powder containing box, a pressed blank conveying device, a pressing machine frame, an upper pressing head assembly, a lower pressing head assembly, a mold device and an orientation magnetic pole. The upper pressure head assembly, the mold device, the lower pressure head assembly and the orientation magnetic pole are arranged in the press frame; the mold device, the upper pressing head assembly, the lower pressing head assembly and the orientation magnetic pole conduct two-way pressing on the alloy powder in the mold cavity under magnetic field orientation together, the alloy powder is pressed into a pressed blank, then the upper pressing head assembly and the lower pressing head assembly are moved in the same direction, and the pressed blank is ejected out of the mold cavity; one side of the press frame is connected with the powder containing box, and the other side of the press frame is connected with the pressed blank conveying device. A connector is arranged at the joint of the press frame and the pressed blank conveying device, and a pressed blank door is arranged at the connector. After the green compact door is opened, the green compact can pass through the interface to be conveyed into the green compact conveying device; the sealed magnetic field pressing machine works under the protective atmosphere, and alloy powder and pressed blanks are isolated from the atmosphere in the magnetic field forming process.

Description

Technical Field

[0001] The invention belongs to the field of advanced equipment, and in particular relates to a sealed magnetic field press, which can be used to manufacture materials such as rare earth permanent magnets. Background Art

[0002] Rare earth permanent magnet materials, mainly sintered NdFeB, are increasingly used due to their excellent magnetic properties. They are widely used in medical magnetic resonance imaging, computer hard disk drives, audio, mobile phones, etc.; with the requirements of energy conservation and low-carbon economy, NdFeB rare earth permanent magnet materials have begun to be widely used in automotive parts, air-conditioning compressors, energy-saving and control motors, hybrid vehicles, wind power generation and other fields.

[0003] The industrial preparation of rare earth permanent magnet materials generally adopts powder metallurgy technology to make rare earth permanent magnet alloy into 3-5μm alloy powder, and then the alloy powder is oriented and formed under a magnetic field. After the molded body is taken out, it needs to be isostatically pressed, and then the pressed green compact is vacuum sintered to obtain rare earth permanent magnet sintered blank, that is, rare earth permanent magnet material. Rare earth permanent magnet alloy powder is very easy to oxidize and can even spontaneously combust in the atmosphere. Therefore, it must be isolated from the atmospheric environment during the production process of rare earth permanent magnet materials. The oxidation problem in the production process has always restricted the development of the industry and seriously affected the consistency of products. In order to improve performance, the surface area increases significantly after the powder particle size is further reduced from 3-5μm to below 3μm. Since rare earth permanent magnet powder cannot be granulated, the powder is more easily oxidized and has worse formability. In order to solve the problem of poor forming, the existing technical solution is to first press the compact into a low-density compact, and then increase the density by isostatic pressing. This method effectively solves the problem of poor forming, but the compact needs to be packaged under a protective atmosphere before isostatic pressing. In addition, the outer packaging of the compact after isostatic pressing is full of isostatic oil, which leads to a poor working environment and easily causes environmental pollution. Therefore, it is very necessary to cancel the isostatic pressing process. Although many companies have invested in the research and development of isostatic pressing technology, it is not ideal. The process technology cannot cover all products, especially for high-performance, large-size and fine-grained products. At present, although the industry also uses sealing equipment to complete the magnetic field molding of alloy powder, it is still impossible to ensure that some links are completely and effectively isolated from the atmosphere during the actual production process of magnetic field molding, which has a certain impact on the quality of the sintered NdFeB material made thereby, limiting the further improvement of material performance.

[0004] In addition, the press equipment and vacuum sintering furnace equipment currently used in the industry have poor production line adaptability. In the process of molding alloy powder into compacts and loading compacts into vacuum sintering furnaces, most of them require manual participation to complete the placement of compact materials in boxes, stacking boxes and loading furnaces, and the transportation of materials between magnetic field molding and vacuum sintering processes. This will bring several problems, including that the materials are easily exposed to the external environment for a long time during manual operation, resulting in different degrees of oxidation, affecting the further improvement of the performance of rare earth permanent magnet materials; in addition, manual operation will not only reduce production efficiency, consume human resources, and increase production costs, but also affect the stability of product quality due to the uncertainty of manual operation, bringing a certain defective rate to the product. Therefore, it is urgent to develop a magnetic field press equipment with better production line adaptability and higher degree of automation to solve this technical status quo. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a sealed magnetic field press for manufacturing high-quality rare earth permanent magnet materials and matching with a highly automated and intelligent rare earth permanent magnet production line.

[0006] The sealed magnetic field press of the present invention comprises a material storage device, a powder loading box, a compact conveying device, a press frame, an upper press head assembly, a lower press head assembly, a mold device and an orientation magnetic pole. The material storage device comprises a powder storage box; the material storage device is arranged above the powder loading box; a powder loading device is arranged in the powder loading box, and the powder loading device automatically loads the alloy powder in the material storage device into the mold cavity of the mold device in a quantitative manner; the upper press head assembly, the mold device, the lower press head assembly and the orientation magnetic pole are arranged in the press frame; the upper press head assembly and the lower press head assembly are arranged above and below the mold device respectively; there are two orientation magnetic poles, which are distributed on both sides of the mold device; the mold device, the upper press head assembly, the lower press head assembly and the orientation magnetic pole together realize bidirectional pressing of the alloy powder in the mold cavity under magnetic field orientation, and press the alloy powder into a compact, and then move the upper press head assembly and the lower press head assembly in the same direction to eject the compact from the mold cavity. One side of the press frame is connected to the powder box, and the other side is connected to the green sheet conveying device; an interface is provided at the connection between the press frame and the green sheet conveying device, and a green sheet door is provided at the interface; after the green sheet door is opened, the green sheet can pass through the interface and be conveyed to the green sheet conveying device; after the green sheet door is closed, the material storage device, the powder box, and the press frame form an independent space isolated from the atmosphere; the press frame can move relative to the green sheet conveying device. The sealed magnetic field press works under a protective atmosphere, and the alloy powder and green sheet are isolated from the atmosphere during the magnetic field forming process.

[0007] The material storage device includes an alloy powder tank and a glove box; the alloy powder tank is connected to the glove box through a valve, and the glove box is connected to the powder storage box; a sealing cover is provided at the connection between the glove box and the powder storage box; when the valve and the sealing cover are opened, the powder in the alloy powder tank can pass through the glove box and enter the powder storage box.

[0008] The applicant found that during the use of the existing magnetic field press, when the powder tank and the press are docked, due to the inherent structural limitations, when the alloy powder is transported from the powder tank to the press, there will be different degrees of oxidation, which is easy to produce a certain proportion of waste powder. After this part of the waste powder enters the press and participates in the manufacture of rare earth permanent magnet compacts, it will cause the performance of the rare earth permanent magnet material to fluctuate, affecting the consistency of the performance of the sintered NdFeB product, and will also limit the further improvement of the material performance. In the present invention, by setting a glove box on the conveying channel between the alloy powder tank and the sealed magnetic field press, and combining the work of the valve and the sealing cover, the alloy powder is completely not in contact with the atmosphere during the process of entering the sealed magnetic field press from the alloy powder tank, thereby overcoming the inherent waste powder problem in the production process of the existing equipment, thereby ensuring the quality and performance consistency of the rare earth permanent magnet material, and further improving the performance of the rare earth permanent magnet material.

[0009] The sealed magnetic field press also includes a first servo hydraulic cylinder assembly and a second servo hydraulic cylinder assembly; the first servo hydraulic cylinder assembly includes a first hydraulic cylinder, a first reversing valve, a first hydraulic pump and a first servo motor; the second servo hydraulic cylinder assembly includes a second hydraulic cylinder, a second reversing valve, a second hydraulic pump and a second servo motor; the first servo hydraulic cylinder assembly and the second servo hydraulic cylinder assembly are both arranged outside the press frame, and the first hydraulic cylinder and the second hydraulic cylinder are respectively connected to the upper pressure head assembly and the lower pressure head assembly; the displacement of the upper pressure head assembly and the lower pressure head assembly and the pressure of the alloy powder in the mold cavity are precisely controlled by controlling the first servo motor and the second servo motor. When the first hydraulic cylinder is working, any other actuator on the first servo hydraulic cylinder assembly cannot work; similarly, when the second hydraulic cylinder is working, any other actuator on the second servo hydraulic cylinder assembly cannot work.

[0010] The upper and lower punch assemblies can move according to the set program curve to achieve bidirectional pressing and protective demolding according to the set process curve. The displacement accuracy of the upper and lower punch assemblies is higher than 0.1mm, the pressure accuracy is higher than 0.1MPa, and the size accuracy of the pressed blank is higher than 0.1mm.

[0011] The sealed magnetic field press also includes a press support frame, on which a press frame is supported; the press frame can move relative to the compact conveying device. In one embodiment, the press support frame is provided with rollers and a third hydraulic cylinder; the third hydraulic cylinder drives the press frame to move relative to the compact conveying device; the press frame can also move relative to the powder box.

[0012] After the alloy powder is loaded into the mold cavity, the alloy powder is oriented in the magnetic field. After the orientation current reaches the set value, the upper pressure head assembly descends according to the set first speed curve, and stops descending when the first set pressure is reached; the lower pressure head assembly ascends according to the set second speed curve, and stops ascending when the second set pressure is reached, thereby realizing two-way pressure; after the mold is demagnetized, the upper pressure head assembly ascends according to the set third speed curve, and ascends rapidly when it reaches the set first position; the lower pressure head assembly ascends according to the set fourth speed curve, and stops ascending when it reaches the set second position.

[0013] The first set pressure ≥ the second set pressure, the second set pressure ≥ 5MPa; the compact density ≥ 4.1g / cm 3 .

[0014] In the powder loading process of the existing magnetic field press, since the rare earth permanent magnet alloy powder cannot be granulated, the powder fluidity is poor, and the magnetic field forming property is very poor, which affects the magnetic field forming effect. In particular, in order to improve the performance of rare earth permanent magnet materials, most of the current industry adopts technical means to refine the alloy powder, resulting in poorer forming property of the alloy powder with finer particle size. In order to solve the problem of poor forming, the existing technical solution is to first press the alloy powder into an intermediate molded body with lower density, and then further increase the density through an isostatic pressing process. Although this method effectively solves the problem of poor forming, the intermediate molded body needs to be packaged under a protective atmosphere before isostatic pressing, which is very troublesome to operate. In addition, the outer packaging of the pressed blank after isostatic pressing is full of isostatic oil, which is troublesome to clean and has a poor working environment. Although there is a demand to cancel isostatic pressing in the industry, the effect has not been ideal, especially for the case of finer alloy powders, isostatic pressing is even more difficult to replace.

[0015] The displacement and pressure of the upper and lower ram assemblies of the sealed magnetic field press of the present invention can be precisely controlled, so that the density of the compact is uniform and the size is consistent, so that the compact has the required density and size. During the pressing process, the upper and lower ram assemblies can move according to the set program curve, and the pressure of the upper and lower ram assemblies can also be output according to the feedback servo, so that even for finer alloy powders, effective pressing and molding can be achieved, so that the compact has uniform density everywhere, so that the inherent technical difficulties in the industry can be overcome, the isostatic pressing in the molding process can be cancelled, and the magnetic properties of the rare earth permanent magnet material can be further improved.

[0016] The green compact conveying device is connected to the press frames of the plurality of sealed magnetic field presses through interfaces; the end of the green compact conveying device is also connected to the first device; the green compact conveying device serves as a conveying channel for the plurality of sealed magnetic field presses, and conveys the green compacts pressed by each sealed magnetic field press to the first device. In a preferred embodiment, the first device is a box for boxing the green compacts pressed by the sealed magnetic field press.

[0017] The sealed magnetic field press of the present invention can be applied to an automatic magnetic field forming system, which includes a box, a conveying box and the above-mentioned sealed magnetic field press; there are multiple sealed magnetic field presses, which are connected side by side to the blank conveying device; in a more preferred embodiment, the automatic magnetic field forming system includes more than 4 sealed magnetic field presses. The sealed magnetic field press can move relative to the blank conveying device. One end of the blank conveying device is connected to the box; the blank conveying device, the box box and the sealed magnetic field press in a working state constitute a space isolated from the atmosphere, which is filled with protective gas; the blanks pressed by the sealed magnetic field press can be automatically conveyed to the blank conveying device, and the blank conveying device serves as a conveying channel of the automatic magnetic field forming system to convey the blanks pressed by each sealed magnetic field press to the box; the box box includes a material box moving device, a material picking mechanism and a first isolation valve; in the box box, the material picking mechanism grabs the blanks and loads them into the sintering material box on the material box moving device; the conveying material box is provided with a material box clamping lifting device. The first and second isolation valves are provided; the conveying material box can be moved to the opposite side of the box loading box, and docked with or removed from the box loading box; after the conveying material box docks with the box loading box, the first isolation valve and the second isolation valve are opened, the box loading box and the conveying material box form a space isolated from the atmosphere, and the material box moving device can be moved into the conveying material box; through the coordinated action of the material box moving device and the material box clamping and lifting device, the multi-layer sintering material boxes on the material box clamping and lifting device can be moved in layers to the material box moving device, or the multi-layer sintering material boxes can be stacked into a stack, and the process of automatically loading the compacts into the sintering material boxes and automatically stacking the sintering material boxes is completed. The first isolation valve and the second isolation valve are closed, and the conveying material box and the box loading box respectively form a space isolated from the atmosphere, and the conveying material box loaded with multi-layer sintering material boxes moves away from the box loading box.

[0018] In a preferred embodiment, after the conveying box is separated from the box packing box, it automatically moves to the opposite side of the vacuum sintering furnace, docks with the vacuum sintering furnace, and conveys the sintering box containing the compact in the conveying box to the vacuum sintering furnace for vacuum sintering. In a preferred embodiment, there are more than 4 vacuum sintering furnaces.

[0019] A sensor for detecting whether there is a green sheet at the location is arranged near the interface where the sealed magnetic field press connects with the green sheet conveying device. The sensor is used to control the green sheets pressed by different sealed magnetic field presses to prevent collision.

[0020] An electronic scale assembly is also provided in the powder loading box; the powder loading device is arranged below the electronic scale assembly; the alloy powder is weighed according to the set weight by the electronic scale assembly and then enters the powder loading device.

[0021] The press frame and the powder box are both movable; when the sealed magnetic field press needs to be maintained, the press frame can be disconnected from the green compact conveying device, and then the press frame and the powder box move away from the green compact conveying device; when the sealed magnetic field press needs to be restored to work after maintenance, the press frame and the powder box move toward the green compact conveying device and restore the connection between the press frame and the green compact conveying device. The movement mode of the press frame and the powder box is selected from at least one of wheeled movement and slide rail movement.

[0022] A blank door is provided at the interface between the sealed magnetic field press and the blank conveying device. When the sealed magnetic field press is disconnected from the blank conveying device, the blank door needs to be closed first to make the blank conveying device airtight and keep the protective gas atmosphere in the enclosed space formed by the blank conveying device, the box and the sealed magnetic field press in working state unchanged. The maintenance of the sealed magnetic field press includes the replacement of molds, cleaning and maintenance of the alloy powder inside the press frame and the powder box. During the operation of the sealed magnetic field press, a small amount of alloy powder will be attached to the press frame and the powder box. This part of the alloy powder needs to be cleaned regularly to avoid exposure to the atmosphere when it accumulates to a certain extent and causes combustion accidents. The blank conveying device serves as a common conveying channel for the blanks in the automatic magnetic field forming system, and conveys the blanks pressed by each sealed magnetic field press to the box. Even if a sealed magnetic field press is undergoing maintenance or is restored to working order after maintenance, the airtightness of the billet conveying device will not be affected. It can still be used as a common conveying channel to provide automatic conveying of billets for other sealed magnetic field presses, ensuring that the automatic magnetic field forming system and the rare earth permanent magnet production line including the automatic magnetic field forming system can still operate normally.

[0023] Although some forms of automatic press systems have appeared in the industry, connecting multiple presses in series through channels, a robotic arm is installed in each press to pick up materials and pack them into boxes, and then multiple carts are used to transfer the boxes in the channels. A large number of robotic arms and carts are used, and the structure and actions are complex and cumbersome. In addition, the boxing action in each press will also result in each press being equipped with a set of empty box conveying devices, and performing cumbersome empty box conveying actions at the same time. The above design not only increases the cost investment of system equipment, but more importantly, it reduces the operating efficiency of the entire system, increases the failure rate, and affects production efficiency. The sealed magnetic field press of the present invention presses the rare earth alloy powder into green compacts and then directly transfers them to a conveyor belt arranged in a green compact conveying device, and collects the green compacts into a unified box through the conveyor belt. The green compact conveying device serves as a common transmission channel for multiple sealed magnetic field presses, and transfers the green compacts pressed by each sealed magnetic field press into the box. Only one set of green compact grabbing mechanism is provided in the box. The green compact grabbing mechanism grabs the green compacts and places them into a sintering material box placed in the box. Then, the conveying material box and the box are connected, and the material box of the box is transferred through the material box of the box. The reciprocating movement of the mobile device and the lifting and lowering of the material box lifting device in the conveying box, together with the action of the green sheet grabbing mechanism, jointly complete the process of automatically loading the green sheets into the sintering material boxes and automatically stacking the sintering material boxes. Moreover, in this process, the empty material boxes are transported to the box loading box, the green sheets are loaded into the material boxes, and the material boxes are stacked at the same time, which not only simplifies the device structure, compresses the equipment volume, and reduces the equipment cost, but more importantly, improves the overall operating efficiency of the system, reduces the equipment failure rate, is conducive to the smooth operation of the entire system, and improves production efficiency.

[0024] In a more preferred embodiment of the present invention, the conveying material box also includes a material bed; there are multiple sintering material boxes in the conveying material box, which are arranged in n layers up and down and placed on the material bed, and n ≥ 3. The aforementioned process of automatically loading the green sheets into the sintering material boxes and automatically stacking the sintering material boxes includes: after the box loading box is docked with the conveying material box, the material box lifting device lifts all n layers of empty sintering material boxes from the material bed, and the material box moving device moves horizontally from the box loading box to the conveying material box, and then, the material box lifting device puts n layers of empty sintering material boxes onto the material box moving device, and then the material box lifting device lifts (n-1) layers of empty sintering material boxes, and the material box moving device moves the remaining 1 layer of empty sintering material boxes from the conveying material box to the box loading box, and then, the material box moving device is lifted and moved to load the green sheets into the sintering material boxes in the box loading box, and then, the material box moving device moves horizontally the sintering material boxes containing the green sheets to the sintering material boxes. The material box is conveyed into the material box, and then the material box lifting device lowers the (n-1) layer of empty sintering material boxes to the top of the layer of sintering material boxes on the material box moving device, and then the material box lifting device lifts the (n-2) layer of empty sintering material boxes, and the material box moving device moves the 2 layers of sintering material boxes including 1 layer of empty sintering material boxes from the conveying material box to the box loading box, and the compacts are loaded into the empty sintering material boxes in the box loading box, and so on, until n layers of empty sintering material boxes are loaded with compacts in the box loading box and then moved to the conveying material box, and then the material box lifting device lifts the n layers of sintering material boxes with compacts from the material box moving device, the material box moving device returns to the box loading box, and the material box lifting device lowers the n layers of sintering material boxes onto the material bed.

[0025] By using the sealed magnetic field press and the automatic magnetic field forming system in the present invention, the process of forming the rare earth permanent magnet alloy powder into a compact by magnetic field and loading the compact into a vacuum sintering furnace in the rare earth permanent magnet material process is automatically completed under nitrogen protection or vacuum conditions, so that the rare earth permanent magnet raw materials that are very easy to oxidize are always effectively isolated from the atmospheric environment, which is conducive to reducing the oxygen content in the material and further improving the performance of the rare earth permanent magnet material; in addition, the material preparation, placing and packing, stacking and loading the furnace in this process, and the transportation of materials between the magnetic field forming and vacuum sintering processes are completely completed in an automated form, which not only improves production efficiency, saves human resources, and reduces production costs, but also eliminates the uncertainty of manual operation, reduces the defective rate of products, overcomes the inherent technical difficulties in the industry, and improves the stability of product quality. Under the same raw material composition and the same manufacturing process parameters, the oxygen content in the rare earth permanent magnet material manufactured by the technical solution in the present invention is reduced by about 200ppm, and the product defective rate caused in the process is reduced by about 30%.

[0026] The present invention is based on the application of new technology production line equipment, mainly solving the following problems: 1. The difficulty in producing NdFeB rare earth permanent magnets is that the rare earth permanent magnet alloy is very easy to oxidize, the powder size is fine, the powder cannot be granulated, and the magnetic field is difficult to form. Some equipment seems to be able to isolate from the atmosphere, but in fact a large amount of nitrogen is wasted, and the oxygen content cannot be reduced. The oxygen content of the equipment production process of this application is lower than 200ppm. In order to reduce the oxidation of rare earth permanent magnet alloy powder, reduce the amount of rare earth, and improve the magnetic properties, rare earth lanthanum cerium is partially replaced by rare earth praseodymium neodymium. The oxygen content of the equipment production process of this application is as low as less than 100ppm.

[0027] 2. Realize the magnetic field formability of refined powder, improve coercivity, and reduce the amount of heavy rare earth elements dysprosium and terbium. When isostatic pressing is cancelled in the prior art, the average particle size of the powder is generally higher than 3.5μm. When the average particle size of the powder in this application is lower than 2.8μm, the sealed magnetic field press also has good magnetic field formability, which is suitable for mass production.

[0028] 3. The powder loading device in the powder loading box of the present application evenly loads the powder into the mold and forms it according to the set process curve. Under the condition of canceling isostatic pressing, the density of the pressed green body is greater than 4.5g / cm 3 .

[0029] 4. The blank conveying device of the present application changes the practice of the prior art. After the blanks are taken out of the mold, they are directly placed on the conveyor belt in the blank conveying device. One conveyor belt connects all the magnetic field presses and conveys the blanks to the same box for boxing. It has a simple and reliable structure, is easy to operate, has low equipment cost and is highly practical.

[0030] 5. In the prior art, a box is set in front of each press, and then the boxes filled with compacts are respectively transferred to the glove box of the vacuum sintering furnace, and the glove box is then connected to the vacuum sintering furnace. The complicated equipment can easily increase the oxygen content of the compacts. In addition, this structure actually cannot do without human participation and cannot realize intelligent production. The conveyor belt of this application directly brings the compacts into the box, and the compacts are uniformly loaded into the sintering box by a robot with vision in the box, and the box is connected to the sintering furnace after being transferred. Low oxygen content, nitrogen saving, and high degree of automation.

[0031] 6. The conveying material box of the prior art cannot be directly connected to the vacuum sintering furnace. The conveying material box is first transferred to a transition glove box, and then transferred to the vacuum sintering furnace by the glove box. The conveying material box of the present invention is connected to the boxing box, and directly connected to the vacuum sintering furnace after the boxing box is removed. The empty sintering material box is transferred back to the boxing box through the conveying material box, realizing intelligent operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of an embodiment of the magnetic field press of the present invention.

[0033] Figure 2 It is a schematic diagram of the top structural layout of an embodiment of the automatic magnetic field forming system involved in the present invention. DETAILED DESCRIPTION

[0034] like Figure 1 As shown, the magnetic field press 1 of the present invention comprises a material storage device 2, a powder box 3, a compact conveying device 10, a press frame 4, an upper press head assembly 5, a lower press head assembly 6, a mold device 7 and an orientation magnetic pole 8. The material storage device 2 is arranged above the powder box 3; a powder loading device 9 is arranged in the powder box 3, and the powder loading device 9 automatically loads the alloy powder in the material storage device 2 into the mold cavity of the mold device 7 in a quantitative manner; the upper press head assembly 5, the mold device 7, the lower press head assembly 6 and the orientation magnetic pole 8 are arranged in the press frame 4; the upper press head assembly 5 and the lower press head assembly 6 are arranged above and below the mold device 7 respectively; there are two orientation magnetic poles 8, which are distributed on both sides of the mold device 7.

[0035] An orientation coil is also arranged in the press frame, and the orientation coil is sleeved on the outer side of the orientation magnetic pole.

[0036] The mold device, together with the upper press head assembly, the lower press head assembly and the orientation magnetic pole, realizes bidirectional pressing of the alloy powder in the mold cavity under magnetic field orientation, pressing the alloy powder into a compact, and then moving the upper press head assembly and the lower press head assembly to eject the compact from the mold cavity.

[0037] One side of the press frame 4 is connected to the powder box 3, and the other side is provided with an interface, which can be connected to the green sheet conveying device 10 through the interface, and a green sheet door 17 is provided at the interface. After the green sheet door 17 is closed, the material storage device 2, the powder box 3, and the press frame 4 form an independent space isolated from the atmosphere; after the green sheet door 17 is opened, the green sheet can be conveyed to the green sheet conveying device 10 through the interface; the press frame 4 can move relative to the green sheet conveying device 10. The working process of the magnetic field press is completed under gas protection.

[0038] The material storage device 2 includes an alloy powder tank 18, a glove box 19 and a powder storage box 20; the alloy powder tank 18 is connected to the glove box 19 through a valve, and the glove box 19 is connected to the powder storage box 20. A sealing cover is provided at the connection between the glove box and the powder storage box; by opening the valve and the sealing cover, the powder in the alloy powder tank can pass through the glove box and enter the powder storage box.

[0039] The magnetic field press 1 also includes a first servo hydraulic cylinder assembly 21 and a second servo hydraulic cylinder assembly 22; the first servo hydraulic cylinder assembly 21 includes a first hydraulic cylinder 23, a first reversing valve, a first hydraulic pump 24 and a first servo motor 25; the second servo hydraulic cylinder assembly 22 includes a second hydraulic cylinder 26, a second reversing valve, a second hydraulic pump 27 and a second servo motor 28; the first servo hydraulic cylinder assembly 21 and the second servo hydraulic cylinder assembly 22 are both arranged on the outside of the press frame 4, and the first hydraulic cylinder 23 and the second hydraulic cylinder 26 pass through the press frame 4 and are respectively connected to the upper press head assembly 5 and the lower press head assembly 6; the displacement of the upper press head assembly 5 and the lower press head assembly 6 and the pressure of the powder in the mold cavity are accurately controlled by controlling the first servo motor 25 and the second servo motor 28.

[0040] When the first hydraulic cylinder is working, any other actuators on the first servo hydraulic cylinder assembly cannot work; similarly, when the second hydraulic cylinder is working, any other actuators on the second servo hydraulic cylinder assembly cannot work.

[0041] The upper and lower pressure head assemblies can move according to the set program curve to achieve bidirectional pressing and protective demolding according to the set process curve. The movement accuracy of the upper and lower pressure head assemblies is higher than 0.05mm, the pressure accuracy is higher than 0.1MPa, and the size accuracy of the pressed blank is higher than 0.05mm.

[0042] The magnetic field press also includes a press support frame 29, on which the press frame 4 is supported; the press support frame is provided with a roller 30 and a third hydraulic cylinder.

[0043] The third hydraulic cylinder drives the press frame to move relative to the compact conveying device; the press frame can also move relative to the powder box.

[0044] After the alloy powder is loaded into the mold cavity, the alloy powder is oriented in the magnetic field. After the orientation current reaches the set value, the upper pressure head assembly descends according to the set first speed curve, and stops descending when the first set pressure is reached; the lower pressure head assembly ascends according to the set second speed curve, and stops ascending when the second set pressure is reached, thereby realizing two-way pressure; after the mold is demagnetized, the upper pressure head assembly ascends according to the set third speed curve, and ascends rapidly when it reaches the set first position; the lower pressure head assembly ascends according to the set fourth speed curve, and stops ascending when it reaches the set second position.

[0045] The first set pressure is ≥ the second set pressure, and the first set pressure is higher than the second set pressure by more than 0.5 MPa, and the second set pressure is ≥ 6 MPa; the compact density is ≥ 4.1 g / cm 3 .

[0046] A sensor for detecting whether there is a green sheet at the location is arranged near the interface where the magnetic field press is connected to the green sheet conveying device. The sensor is used to control the green sheets pressed by different magnetic field presses to prevent collision.

[0047] An electronic scale assembly is also provided in the powder loading box; the powder loading device is arranged below the electronic scale assembly; the alloy powder is weighed according to the set weight by the electronic scale assembly and then enters the powder loading device.

[0048] The magnetic field press is also provided with a transfer mechanism, which automatically removes the compact ejected from the mold cavity and places it in a compact conveying device.

[0049] Both the press frame and the powder box are movable; when the magnetic field press needs maintenance, the press frame can be disconnected from the green compact conveying device, and then the press frame and the powder box are moved away from the green compact conveying device; when the magnetic field press needs to be restored to working condition after maintenance, the press frame and the powder box are moved toward the green compact conveying device, and the connection between the press frame and the green compact conveying device is restored. The movement mode of the press frame and the powder box is selected from at least one of wheeled movement and slide rail movement. Figure 1 In the implementation manner, rollers are provided at the lower part of the press support frame and the powder box, and movement can be achieved by the rollers.

[0050] The green compact conveying device is connected to the press frames of the plurality of magnetic field presses through interfaces. The end of the green compact conveying device is also connected to a first device; the green compact conveying device serves as a common conveying channel for the plurality of magnetic field presses, and conveys the green compacts pressed by each magnetic field press to the first device. In a preferred embodiment, the first device is a box for boxing the green compacts pressed by the magnetic field press.

[0051] The magnetic field press of the present invention can be applied to an automatic magnetic field forming system, such as Figure 2 As shown, the system includes a box 11, a conveying material box 15 and the magnetic field press 1 mentioned above; there are multiple magnetic field presses 1, and the press frames of the multiple magnetic field presses are connected side by side to the compact conveying device 10. Figure 2 In the illustrated embodiment, the automatic magnetic field forming system includes four magnetic field presses. The press frame of the magnetic field press can be moved relative to the blank conveying device. One end of the blank conveying device 10 is connected to the box 11; the blank conveying device 10, the box 11 and the magnetic field press in working state constitute a space isolated from the atmosphere, which is filled with protective gas. The blanks pressed by the magnetic field press can be automatically transferred to the blank conveying device, and the blank conveying device serves as a transfer channel of the automatic magnetic field forming system to transfer the blanks pressed by each magnetic field press to the box.

[0052] The box loading box 11 includes a material box moving device, a material taking mechanism and a first isolation valve 12; in the box loading box 11, the material taking mechanism grabs the compact and loads it into the sintering material box 13 on the material box moving device. Figure 1 and Figure 2 As shown, a conveyor belt 14 is provided in the blank conveying device 10, and the conveyor belt 14 extends through the interface into the box 11; after the blank is ejected from the mold cavity, it moves to the conveyor belt 14 in the blank conveying device, and is conveyed to the box 11 through the conveyor belt 14.

[0053] The conveying material box 15 is provided with a material box clamping lifting device and a second isolation valve 16. The conveying material box 15 can be moved to the opposite side of the box loading box 11, and docked with or removed from the box loading box 11. After the conveying material box 15 is docked with the box loading box 11, the first isolation valve 12 and the second isolation valve 16 are opened, the box loading box 11 and the conveying material box 15 form a space isolated from the atmosphere, and the material box moving device can be moved into the conveying material box 15; through the coordinated action of the material box moving device and the material box clamping lifting device, the multi-layer sintering material boxes on the material box clamping lifting device can be moved to the material box moving device in layers, or the multi-layer sintering material boxes can be stacked into a stack, and the process of automatically loading the compacts into the sintering material boxes and automatically stacking the sintering material boxes is completed together. Close the first isolation valve 12 and the second isolation valve 16, the conveying material box 15 and the box loading box 11 respectively form a space isolated from the atmosphere, and the conveying material box 15 loaded with multi-layer sintering material boxes moves away from the box loading box 11.

[0054] In a preferred embodiment, after the conveying box is separated from the box packing box, it automatically moves to the opposite side of the vacuum sintering furnace, docks with the vacuum sintering furnace, and conveys the sintering box containing the compact in the conveying box to the vacuum sintering furnace for vacuum sintering. In a preferred embodiment, there are more than 4 vacuum sintering furnaces.

[0055] A press door is provided at the interface between the magnetic field press and the press conveyor. When the magnetic field press is disconnected from the press conveyor, the press door needs to be closed first to seal the press conveyor and prevent air leakage, and to maintain the protective gas atmosphere in the enclosed space composed of the press conveyor, the box and the magnetic field press in working state. The maintenance of the automatic magnetic field press includes the replacement of molds, the cleaning and inspection of alloy powder inside the press frame and the powder box.

[0056] The box loading box includes a box loading box body, one end of which is connected to the first isolation valve, and the other end is connected to the compact conveying device; a material taking mechanism and a material box moving device are arranged in the box loading box body; the material taking mechanism grabs the compact conveyed into the box loading box body and puts it into the sintering material box placed on the material box moving device; after the box loading box and the conveying material box are docked, the material box moving device can reciprocate between the box loading box and the conveying material box. The material box moving device can move horizontally or up and down.

[0057] In a more preferred embodiment of the present invention, the conveying material box also includes a material bed; there are multiple sintering material boxes in the conveying material box, which are arranged in n layers up and down and placed on the material bed, and n ≥ 3. The aforementioned process of automatically loading the green sheets into the sintering material boxes and automatically stacking the sintering material boxes includes: after the box loading box is docked with the conveying material box, the material box lifting device lifts all n layers of empty sintering material boxes from the material bed, and the material box moving device moves horizontally from the box loading box to the conveying material box, and then, the material box lifting device puts n layers of empty sintering material boxes onto the material box moving device, and then the material box lifting device lifts (n-1) layers of empty sintering material boxes, and the material box moving device moves the remaining 1 layer of empty sintering material boxes from the conveying material box to the box loading box, and then, the material box moving device is lifted and moved to load the green sheets into the sintering material boxes in the box loading box, and then, the material box moving device moves horizontally the sintering material boxes containing the green sheets to the sintering material boxes. The material box is conveyed into the material box, and then the material box lifting device lowers the (n-1) layer of empty sintering material boxes to the top of the layer of sintering material boxes on the material box moving device, and then the material box lifting device lifts the (n-2) layer of empty sintering material boxes, and the material box moving device moves the 2 layers of sintering material boxes including 1 layer of empty sintering material boxes from the conveying material box to the box loading box, and the compacts are loaded into the empty sintering material boxes in the box loading box, and so on, until n layers of empty sintering material boxes are loaded with compacts in the box loading box and then moved to the conveying material box, and then the material box lifting device lifts the n layers of sintering material boxes with compacts from the material box moving device, the material box moving device returns to the box loading box, and the material box lifting device lowers the n layers of sintering material boxes onto the material bed.

Claims

1. A sealed magnetic field press, characterized in that: It includes a material storage device, a powder box, a compact conveying device, a press frame, an upper pressure head assembly, a lower pressure head assembly, a mold device and an orientation magnetic pole; the material storage device includes a powder storage box; the material storage device is arranged above the powder box; a powder loading device is arranged in the powder box, and the powder loading device automatically loads the alloy powder in the powder storage box into the mold cavity of the mold device in a quantitative manner; the upper pressure head assembly, the mold device, the lower pressure head assembly and the orientation magnetic pole are arranged in the press frame; the upper pressure head assembly and the lower pressure head assembly are respectively arranged above and below the mold device; there are two orientation magnetic poles, which are distributed on both sides of the mold device; the mold device and the upper pressure head assembly The upper and lower punch assemblies and the oriented magnetic poles together carry out bidirectional pressing on the alloy powder in the mold cavity under the orientation of the magnetic field to press the alloy powder into a green compact. Then, the upper and lower punch assemblies are moved in the same direction to eject the green compact from the mold cavity. One side of the press frame is connected to the powder loading box, and the other side is connected to the green compact conveying device. An interface is provided at the connection between the press frame and the green compact conveying device, and a green compact door is provided at the interface. After the green compact door is opened, the green compact can be conveyed to the green compact conveying device through the interface. The sealed magnetic field press works under a protective atmosphere, and the alloy powder and the green compact are isolated from the atmosphere during the magnetic field forming process.

2. The sealed magnetic field press according to claim 1, characterized in that: The material storage device also includes an alloy powder tank and a glove box; the alloy powder tank is connected to the glove box through a valve, and the glove box is connected to the powder storage box; a sealing cover is provided at the connection between the glove box and the powder storage box; by opening the valve and the sealing cover, the powder in the alloy powder tank can enter the powder storage box through the glove box.

3. The sealed magnetic field press according to claim 1, characterized in that: The sealed magnetic field press also includes a first servo hydraulic cylinder assembly and a second servo hydraulic cylinder assembly; the first servo hydraulic cylinder assembly includes a first hydraulic cylinder, a first reversing valve, a first hydraulic pump and a first servo motor; the second servo hydraulic cylinder assembly includes a second hydraulic cylinder, a second reversing valve, a second hydraulic pump and a second servo motor; the first hydraulic cylinder and the second hydraulic cylinder are respectively connected to the upper pressure head assembly and the lower pressure head assembly; the displacement of the upper pressure head assembly and the lower pressure head assembly and the pressure applied to the alloy powder in the mold cavity are precisely controlled by controlling the first servo motor and the second servo motor.

4. The sealed magnetic field press according to claim 3, characterized in that: The upper and lower punch assemblies can move according to the set program curve to achieve bidirectional pressing and protective demolding according to the set process curve. The displacement accuracy of the upper and lower punch assemblies is higher than 0.1mm, the pressure accuracy is higher than 1MPa, and the size accuracy of the pressed blank is higher than 0.1mm.

5. The sealed magnetic field press according to claim 1, characterized in that: The sealed magnetic field press also includes a press support frame, on which a press frame is supported; the press frame is movable relative to the green sheet conveying device.

6. The sealed magnetic field press according to claim 1, characterized in that: The sealed magnetic field press also includes a press support frame, on which the press frame is supported; the press support frame is provided with rollers and a third hydraulic cylinder; the third hydraulic cylinder drives the press frame to move relative to the compact conveying device; the press frame can also move relative to the powder box.

7. The sealed magnetic field press according to claim 1, characterized in that: After the alloy powder is loaded into the mold cavity, the alloy powder is oriented in the magnetic field. After the orientation current reaches the set value, the upper pressure head assembly descends according to the set first speed curve, and stops descending when the first set pressure is reached; the lower pressure head assembly ascends according to the set second speed curve, and stops ascending when the second set pressure is reached, thereby realizing two-way pressure; after the mold is demagnetized, the upper pressure head assembly ascends according to the set third speed curve, and ascends rapidly when it reaches the set first position; the lower pressure head assembly ascends according to the set fourth speed curve, and stops ascending when it reaches the set second position.

8. The sealed magnetic field press according to claim 7, characterized in that: The first set pressure ≥ the second set pressure, the second set pressure ≥ 5MPa; the compact density ≥ 4.1g / cm 3 .

9. The sealed magnetic field press according to claim 1, characterized in that: The blank conveying device is connected to the press frames of multiple sealed magnetic field presses through interfaces; the end of the blank conveying device is also connected to the first device; the blank conveying device serves as a conveying channel for multiple sealed magnetic field presses, and conveys the blanks pressed by each sealed magnetic field press to the first device.

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