Hot pressing and hot deformation apparatus for magnetic powder, and hot pressing and hot deformation method.

Abstract

This invention discloses a hot pressing and hot deformation apparatus for magnetic powder, as well as a method for hot pressing and hot deformation. [Solution] The hot pressing and hot deformation apparatus for magnetic powder includes a female die, an upper punch assembly, and a lower punch assembly. The upper punch assembly includes an upper inner punch and an upper outer sleeve, with at least a portion of the upper inner punch drilled into the upper outer sleeve cavity and the upper inner punch being set to move up and down relative to the upper outer sleeve. The lower punch assembly includes a lower inner punch and a lower outer sleeve, with at least a portion of the lower inner punch drilled into the lower outer sleeve cavity and the lower inner punch being set to move up and down relative to the lower outer sleeve. The diameter of the lower outer sleeve cavity is smaller than the diameter of the upper outer sleeve cavity. This hot pressing and hot deformation apparatus for magnetic powder can improve the magnetic properties of neodymium iron boron magnets.

Description

Technical Field

[0001] The present invention relates to a hot press and hot deformation device for magnetic powder, and a hot press / hot deformation method.

Background Art

[0002] Neodymium iron boron magnets are third-generation rare earth permanent magnet materials, which have high magnetic properties and excellent cost performance, and are widely applied in fields such as machinery, information, energy, and transportation. The hot press / hot deformation process is a near net shape manufacturing technology.

[0003] CN108022743A discloses magnet manufacturing equipment including a base fixing table, an inner mold, a double-acting outer mold, and a punch. The inner mold is fixedly installed on the base fixing table. The double-acting outer mold is arranged along the outer periphery of the inner mold. When the double-acting outer mold moves to the first position and the second position relative to the inner mold, a first accommodation space and a second accommodation space are respectively formed between the double-acting outer mold and the inner mold, and the first accommodation space and the second accommodation space respectively have a first inner diameter and a second inner diameter. When the double-acting outer mold moves to the first position, the punch is used to compress a magnet ingot arranged in the first accommodation space into an isotropic magnet semi-finished product. When the double-acting outer mold moves to the second position, the punch is used to press the isotropic magnet semi-finished product arranged in the second accommodation space into a hollow anisotropic magnet.

[0004] CN117116644A discloses a molding die for a hot press and hot deformation magnet, including a fixed die, a first movable die, a second movable die, and a third movable die. The fixed die is provided with a first cavity and a second cavity that are in communication and share the same centerline, and the cross-section of the first cavity is larger than the cross-section of the second cavity. The first movable die fits into the second cavity and is movable within the first cavity and the second cavity along the centerline, the third movable die is slidably fitted into the second movable die, and the combination of the second and third movable dies fits into the first cavity, the second movable die is movable within the first cavity and the second movable die is movable within the first cavity along the centerline, the third movable die is movable within the first cavity along the centerline, and the second movable die fits into the second cavity.

[0005] Because high-temperature hot deformation is performed immediately after hot pressing with the above-mentioned mold, the high-temperature exposure time of the hot-pressed blank is prolonged, which can easily lead to crack formation in the magnets and a decrease in magnetic properties. [Overview of the Initiative]

[0006] In view of this, one object of the present invention is to provide a hot pressing and hot deformation apparatus for magnetic powder that can improve the magnetic properties of neodymium iron boron magnets. Another object of the present invention is to provide a hot pressing and hot deformation method that can improve the magnetic properties of neodymium iron boron magnets.

[0007] The above objective will be achieved through the following configuration.

[0008] In one embodiment, the present invention relates to a hot pressing and hot deformation apparatus for magnetic powder, comprising a female mold, an upper punch assembly and a lower punch assembly, The female mold has a cavity, and the cavity has an upper cavity opening and a lower cavity opening. The upper punch assembly includes an upper inner punch and an upper outer sleeve, the upper outer sleeve having an upper outer sleeve cavity, at least a portion of the upper inner punch being drilled within the upper outer sleeve cavity, the upper inner punch being set to move up and down relative to the upper outer sleeve, and the outer diameter of the upper inner punch matching the diameter of the upper outer sleeve cavity. The lower punch assembly includes a lower inner punch and a lower outer sleeve, the lower outer sleeve having a lower outer sleeve cavity, at least a portion of the lower inner punch being drilled in the lower outer sleeve cavity, the lower inner punch being set to move up and down relative to the lower outer sleeve, the diameter of the lower outer sleeve cavity being smaller than the diameter of the upper outer sleeve cavity, and the outer diameter of the lower inner punch matching the diameter of the lower outer sleeve cavity, thereby providing a hot pressing and hot deformation apparatus for magnetic powder.

[0009] According to the hot pressing and hot deformation apparatus for magnetic powder of the present invention, preferably, the outer diameter of at least a portion of the upper outer sleeve matches the diameter of the cavity, and the outer diameter of at least a portion of the lower outer sleeve matches the diameter of the cavity.

[0010] According to the hot pressing and hot deformation apparatus for magnetic powder of the present invention, preferably, the ratio of the diameter of the lower outer sleeve cavity to the diameter of the upper outer sleeve cavity is 1:(1.2~5.5), and the ratio of the diameter of the upper outer sleeve cavity to the diameter of the cavity is 1:(1.05~1.5).

[0011] According to the hot pressing and hot deformation apparatus for magnetic powder of the present invention, preferably, the length of the upper inner punch is greater than or equal to the length of the upper outer sleeve cavity, the length of the lower inner punch is greater than or equal to the length of the lower outer sleeve cavity, and the length of the lower outer sleeve is greater than or equal to the length of the female die.

[0012] In another aspect, the present invention relates to a method for performing hot pressing and hot deformation of magnetic powder using a hot pressing and hot deformation apparatus,

[0013] Step (1) is to obtain a neodymium iron boron hot press blank by applying pressure to neodymium iron boron magnetic powder and performing a hot press by moving the lower inner punch upward while maintaining the upper punch assembly, female die and lower outer sleeve of the assembled device in a fixed state, Step (1) is a state in which the assembled device has the upper end of the lower outer sleeve located inside the cavity, the lower inner punch separated from the upper end of the lower outer sleeve, a first cavity formed by the lower outer sleeve and the lower inner punch inside the cavity, neodymium iron boron magnetic powder in the first cavity, the upper inner punch and the bottom of the upper outer sleeve are flush, and the upper inner punch and the bottom of the upper outer sleeve are in contact with the upper end of the lower outer sleeve, Step (2) involves moving the upper inner punch upward so as to form a second cavity between the upper inner punch and the upper outer sleeve, and moving the lower inner punch upward so as to align the upper end of the lower inner punch with the upper end of the lower outer sleeve, thereby inserting the neodymium iron boron hot press blank into the second cavity, and while maintaining the lower punch assembly, female die and upper outer sleeve in a fixed state, moving the upper inner punch downward to apply pressure to the neodymium iron boron hot press blank to perform pre-deformation and form a pre-deformed blank. Step (3) involves moving the upper outer sleeve upward so that the bottom of the upper outer sleeve is lower than the bottom of the upper inner punch, keeping the relative position of the upper outer sleeve and the upper inner punch constant, and while maintaining the top of the lower inner punch and the top of the lower outer sleeve flush, moving the upper punch assembly and the lower punch assembly in the direction of the pre-deformed blank to perform ultimate deformation and obtain a neodymium iron boron magnet. This provides a method that includes [something].

[0014] According to the method of the present invention, preferably, in step (1), hot pressing is performed under conditions of an inert atmosphere and a temperature of 500 to 700°C; in step (2), preliminary deformation is performed under conditions of an inert atmosphere and a temperature of 650 to 900°C; and in step (3), final deformation is performed under conditions of an inert atmosphere and a temperature of 750 to 950°C.

[0015] According to the method of the present invention, preferably in step (1), the pressure applied to the neodymium iron boron magnetic powder is 100 to 500 MPa, and the holding time is 10 to 500 s. In step (2), the pressure applied to the neodymium iron boron hot press blank is 50 to 500 MPa, and the holding time is 1 to 100 s. In step (3), the pressure applied to the pre-deformed blank is 80-600 MPa, and the holding time is 30-300 s.

[0016] According to the method of the present invention, preferably in step (3), the moving speed of the upper punch assembly in the pre-deformed blanking direction is 0.7 to 1.5 times the moving speed of the lower punch assembly in the pre-deformed blanking direction.

[0017] The method according to the present invention preferably further includes the steps of moving the upper punch assembly to the outside of the cavity, moving the lower inner punch and / or lower outer sleeve upward to push the ultimate deformation blank obtained by ultimate deformation out of the cavity, and cooling to 20-35°C to obtain a neodymium iron boron magnet.

[0018] According to the method of the present invention, preferably, the neodymium iron boron magnetic powder is neodymium iron boron rapidly solidified fine powder.

[0019] The hot pressing and hot deformation apparatus for magnetic powder according to the present invention completes the hot pressing and hot deformation of magnetic powder, and in the hot deformation process, it is possible to first perform pre-deformation at a relatively low temperature with a small amount of deformation, and then complete ultimate deformation at a relatively high temperature, thereby shortening the hot deformation time at high temperatures for neodymium iron boron hot press blanks, reducing the probability of cracking in magnets, and improving the magnetic properties of magnets. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1 is a schematic diagram of the configuration of a hot pressing and hot deformation apparatus for magnetic powder according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram of the state of the device in the hot pressing process. [Figure 3] Figure 3 is a schematic diagram of the state of the device in the preliminary deformation process. [Figure 4] Figure 4 is a schematic diagram of the state of the device in the final deformation process.

Explanation of Signs

[0021] 1... Female mold, 101... Cavity, 201... Upper inner punch, 202... Upper outer sleeve, 2021... Upper outer sleeve cavity, 203... Upper inner punch drive, 301... Lower inner punch, 302... Lower outer sleeve, 3021... Lower outer sleeve cavity, 303... Lower outer sleeve drive, 4... Neodymium iron boron hot press blank, 5... Preliminary deformation blank, 6... Final deformation blank. [Embodiments for Carrying out the Invention]

[0022] The present invention will be further described below in light of specific examples, but the protection scope of the present invention is not limited thereto.

[0023] <Hot Pressing and Hot Forming Device for Magnetic Powder> The hot pressing and hot forming device for magnetic powder according to the present invention includes a female mold, an upper punch assembly, and a lower punch assembly. Each component will be described in detail below.

[0024] Female mold The female mold according to the present invention has a cavity. The cavity has a cavity upper end opening and a cavity lower end opening. The cavity may have a shape such as a cylinder or a rectangular parallelepiped. The diameters of each part of the cavity are substantially equal.

[0025] The diameter of the cavity may be 10 to 100 mm. In some embodiments, the diameter of the cavity is 20 to 70 mm.

[0026] Upper punch assembly The upper punch assembly according to the present invention is separable from the female mold. The lower part of the upper punch assembly can be inserted into the cavity through the upper end opening of the cavity.

[0027] The upper punch assembly includes an upper inner punch and an upper outer sleeve. In some embodiments, it further includes an upper inner punch drive.

[0028] The upper outer sleeve has an upper outer sleeve cavity. The upper outer sleeve cavity penetrates the upper outer sleeve. The ratio of the diameter of the upper outer sleeve cavity to the diameter of the cavity may be 1:(1.05~1.5), preferably 1:(1.1~1.4), and more preferably 1:(1.2~1.3). The diameters of each part of the upper outer sleeve cavity are approximately equal. The diameter of the upper outer sleeve cavity may be 5~70mm. In some embodiments, the diameter of the upper outer sleeve cavity is 10~50mm. This contributes to improving the magnetic properties of the magnet.

[0029] At least a portion of the upper outer sleeve has an outer diameter that matches the diameter of the cavity. The length of the upper outer sleeve is greater than or equal to the length of the female mold.

[0030] In some embodiments, the upper outer sleeve consists of a first upper outer sleeve unit and a second upper outer sleeve unit. The first upper outer sleeve unit is located above the second upper outer sleeve unit. The outer diameter of the second upper outer sleeve unit matches the cavity diameter. The length of the second upper outer sleeve unit is greater than or equal to the length of the female die. The outer diameter of the first upper outer sleeve unit is greater than the outer diameter of the second upper outer sleeve unit, thereby forming an ear portion. The ear portion of the upper outer sleeve acts as a stopper for the upper inner punch.

[0031] When the upper punch assembly and the female mold are assembled, the center line of the upper outer sleeve cavity and the center line of the cavity coincide.

[0032] At least a portion of the upper internal punch is drilled within the upper outer sleeve cavity. The upper internal punch is vertically movable relative to the upper outer sleeve. The outer diameter of the upper internal punch matches the diameter of the upper outer sleeve cavity. The length of the upper internal punch may be greater than or equal to the length of the upper outer sleeve cavity. The centerline of the upper internal punch may coincide with the centerline of the upper outer sleeve cavity.

[0033] The upper internal punch drive is connected to the top of the upper internal punch. The upper internal punch drive and the upper internal punch may be integrated into a single structure.

[0034] S1 shows the projection of the upper inner punch drive onto the horizontal plane. S2 shows the projection of the upper inner punch onto the horizontal plane. S2 is within the range of S1. In some embodiments, the centers of S1 and S2 coincide. The upper inner punch drive can apply external pressure uniformly to the upper inner punch and, in combination with the lugs of the upper outer sleeve, acts as a stopper for the upper inner punch.

[0035] Lower punch assembly At least a portion of the lower punch assembly according to the present invention is located within the cavity. Specifically, the upper part of the lower punch assembly is inserted into the cavity from the lower end opening of the cavity.

[0036] The lower punch assembly includes a lower inner punch and a lower outer sleeve. In some embodiments, it further includes a lower inner punch drive.

[0037] The lower outer sleeve has a lower outer sleeve cavity. The lower outer sleeve cavity penetrates the lower outer sleeve. The ratio of the diameter of the lower outer sleeve cavity to the diameter of the upper outer sleeve cavity may be 1:(1.2~5.5), preferably 1:(1.3~3), and more preferably 1:(1.4~2). The diameters of each part of the lower outer sleeve cavity are approximately equal. The diameter of the lower outer sleeve cavity may be 2~50mm. In some embodiments, the diameter of the lower outer sleeve cavity is 7~30mm. This contributes to improving the magnetic properties of the magnet.

[0038] At least a portion of the lower outer sleeve has an outer diameter that matches the diameter of the cavity. The length of the lower outer sleeve may be greater than or equal to the length of the female mold.

[0039] In some embodiments, the lower outer sleeve consists of a first lower outer sleeve unit and a second lower outer sleeve unit. The first lower outer sleeve unit is located below the second lower outer sleeve unit. The outer diameter of the second lower outer sleeve unit matches the cavity diameter. The length of the second lower outer sleeve unit is greater than or equal to the length of the female die. The outer diameter of the first lower outer sleeve unit is larger than that of the second lower outer sleeve unit, thereby forming an ear portion. The ear portion of the lower outer sleeve acts as a stopper for the lower inner punch.

[0040] In some embodiments, the center line of the lower outer sleeve cavity and the center line of the cavity coincide.

[0041] At least a portion of the lower internal punch is drilled within the lower external sleeve cavity. The lower internal punch is vertically movable relative to the lower external sleeve. The outer diameter of the lower internal punch matches the diameter of the lower external sleeve cavity. The length of the lower internal punch may be greater than or equal to the length of the lower external sleeve cavity. The centerline of the lower internal punch may coincide with the centerline of the lower external sleeve cavity.

[0042] The lower internal punch drive is connected to the bottom of the lower internal punch. The lower internal punch drive and the lower internal punch may be an integrated structure.

[0043] S3 is the projection of the lower inner punch drive onto the horizontal plane. S4 is the projection of the lower inner punch onto the horizontal plane. S4 is within the range of S3. In some embodiments, the centers of S3 and S4 coincide. The lower inner punch drive can uniformly apply externally applied pressure to the lower inner punch and, in combination with the lugs of the lower outer sleeve, acts as a stopper for the lower inner punch.

[0044] <Hot pressing and hot deformation methods> The hot pressing and hot deformation method according to the present invention uses the above-mentioned hot pressing and hot deformation apparatus for magnetic powder and includes a hot pressing step (1), a preliminary deformation step (2), and an ultimate deformation step (3). Each step will be described in detail below.

[0045] Hot press step While maintaining the fixed position of the assembled device's upper punch assembly, female die, and lower outer sleeve, the lower inner punch is moved upward to apply pressure to the neodymium iron boron magnetic powder and perform hot pressing to obtain a neodymium iron boron hot press blank. In this assembled device, the upper end of the lower outer sleeve is located inside the cavity, the lower inner punch is separated from the upper end of the lower outer sleeve, a first cavity is formed within the cavity by the lower outer sleeve and the lower inner punch, and the neodymium iron boron magnetic powder is contained within the first cavity, the upper inner punch and the bottom of the upper outer sleeve are flush, and the upper inner punch and the bottom of the upper outer sleeve are in contact with the upper end of the lower outer sleeve.

[0046] Preferably, before assembling the apparatus, a release agent is first applied to the apparatus. Specifically, the release agent may be applied to the inner walls of the cavities, the inner walls of the upper outer sleeve cavity, the outer surface of the upper inner punch, the inner walls of the lower outer sleeve cavity, and the outer surface of the lower inner punch.

[0047] The neodymium iron boron magnetic powder may be a rapidly solidified magnetic powder. The neodymium iron boron magnetic powder may contain Pr, Nd, Fe, Co, Ga, and B. The total content of Pr and Nd may be 20 to 40 wt%, preferably 25 to 35 wt%. The mass ratio of Pr to Nd may be 25:(60 to 90), preferably 25:(70 to 80). The Fe content may be 50 to 75 wt%, preferably 60 to 65 wt%. The Co content may be 1 to 15 wt%, preferably 3 to 10 wt%. The Ga content may be 0.1 to 3 wt%, preferably 0.3 to 1 wt%. The B content may be 0.1 to 2 wt%, preferably 0.5 to 1.5 wt%.

[0048] According to one embodiment of the present invention, the amount of neodymium iron boron magnetic powder used may be 60 to 120 g.

[0049] Hot pressing is performed under an inert gas atmosphere. The inert gas is one or more selected from nitrogen gas, helium gas, neon gas, and argon gas. Preferably, the inert gas is argon gas.

[0050] The hot pressing temperature may be 500 to 700°C, preferably 550 to 650°C, and more preferably 600 to 620°C.

[0051] The hot press speed may be 0.05 to 5 mm / s, preferably 0.5 to 3 mm / s. In some embodiments, the hot press speed is 1 to 2 mm / s.

[0052] The hot press pressure may be 100 to 500 MPa, preferably 250 to 400 MPa. In some embodiments, the hot press pressure is 300 to 350 MPa.

[0053] The hot pressing time may be 10 to 500 seconds, preferably 50 to 300 seconds, and more preferably 100 to 200 seconds.

[0054] The above conditions help to obtain a dense and uniform isotropic neodymium iron boron hot-pressed blank, thereby improving the magnetic properties of the magnet.

[0055] Preliminary deformation step The upper inner punch is moved upward to form a second cavity between the upper inner punch and the upper outer sleeve, and the lower inner punch is moved upward so that the upper end of the lower inner punch and the upper end of the lower outer sleeve are flush, thereby inserting the neodymium iron boron hot press blank into the second cavity. While maintaining the lower punch assembly, female die, and upper outer sleeve in a fixed state, the upper inner punch is moved downward to apply pressure to the neodymium iron boron hot press blank, causing pre-deformation and forming a pre-deformed blank. The height of the second cavity is greater than or equal to the height of the neodymium iron boron hot press blank.

[0056] Preliminary deformation is performed under an inert gas atmosphere. The inert gas is one or more selected from nitrogen gas, helium gas, neon gas, and argon gas. Preferably, the inert gas is argon gas.

[0057] The pre-deformation temperature may be 650 to 900°C, preferably 680 to 800°C, and more preferably 700 to 750°C. The pre-deformation temperature is lower than the ultimate deformation temperature.

[0058] The pre-deformation press speed may be 0.01 to 5 mm / s, preferably 0.05 to 2 mm / s. In some embodiments, the pre-deformation press speed is 0.1 to 0.5 mm / s.

[0059] The pre-deformation pressure may be 50 to 500 MPa, preferably 100 to 450 MPa. In some embodiments, the pre-deformation pressure is 270 to 300 MPa.

[0060] The pre-deformation pressing time may be 1 to 100 seconds, preferably 10 to 80 seconds, and more preferably 20 to 50 seconds.

[0061] The above pre-deformation conditions can reduce the occurrence of magnet cracking and improve the magnetic properties of the magnet.

[0062] Final transformation step The upper outer sleeve is moved upward so that the bottom of the upper outer sleeve is lower than the bottom of the upper inner punch, keeping the relative position between the upper outer sleeve and the upper inner punch constant, and while maintaining the top of the lower inner punch and the top of the lower outer sleeve flush, the upper punch assembly and the lower punch assembly are moved in the direction of the pre-deformed blank to perform ultimate deformation and obtain a neodymium iron boron magnet.

[0063] In some embodiments, the upper outer sleeve is moved upward so that the bottom of the upper outer sleeve and the bottom of the upper inner punch are flush. In this state, the upper punch assembly and the lower punch assembly are moved in the direction of the pre-deformed blank to perform ultimate deformation and obtain a neodymium iron boron magnetic block.

[0064] In some embodiments, the upper outer sleeve is moved upward so that its bottom is higher than the bottom of the upper inner punch. In this state, the upper punch assembly and the lower punch assembly are moved in the direction of the pre-deformed blank to perform ultimate deformation and obtain a neodymium iron boron magnet ring.

[0065] Preferably, the movement speed of the upper punch assembly in the pre-deformed blanking direction is 0.7 to 1.5 times, preferably 0.9 to 1.2 times, and more preferably 1 to 1.1 times, the movement speed of the lower punch assembly in the pre-deformed blanking direction.

[0066] The ultimate deformation is carried out in an inert gas atmosphere. The inert gas is one or more selected from nitrogen gas, helium gas, neon gas, and argon gas. Preferably, the inert gas is argon gas.

[0067] The ultimate deformation temperature may be 750 to 950°C, preferably 800 to 900°C, and more preferably 840 to 880°C.

[0068] The ultimate deformation press speed may be 0.01 to 3 mm / s, preferably 0.05 to 0.5 mm / s. In some embodiments, the ultimate deformation press speed is 0.1 to 0.3 mm / s.

[0069] The ultimate deformation pressure may be 80 to 600 MPa, preferably 150 to 350 MPa. In some embodiments, the ultimate deformation pressure is 180 to 200 MPa.

[0070] The final deformation pressing time may be 30 to 300 seconds, preferably 50 to 200 seconds, and more preferably 100 to 150 seconds.

[0071] The upper and lower punch assemblies according to the present invention can be subjected to pressure from both opposing directions, and the force is applied uniformly by a pre-deformed blank. The ultimate deformation conditions contribute to improving the magnetic properties of the magnet.

[0072] In some embodiments, the process further includes moving the upper punch assembly to the outside of the cavity, moving the lower inner punch and / or lower outer sleeve upward to push the ultimate-deformed blank obtained by ultimate deformation out of the cavity, and then cooling it to 20-35°C to obtain a neodymium iron boron magnet.

[0073] The measurement method will be explained below.

[0074] Magnetic properties: A neodymium iron-boron magnetic block is cut into cylindrical measurement samples with a diameter of 10 mm and a height of 3-5 mm using a wire electrical discharge cutter, and the magnetic properties of the measurement samples are measured using a pulsed magnetic field magnetometer.

[0075] Examples 1-3 As shown in Figure 1, the hot pressing and hot deformation apparatus for magnetic powder in this embodiment includes a female die 1, an upper punch assembly, and a lower punch assembly.

[0076] The female mold 1 has a cavity 101. The cavity 101 has an upper cavity opening and a lower cavity opening.

[0077] The upper punch assembly is separable from the female mold 1, and the lower part of the upper punch assembly is insertable into the cavity 101 through the upper end opening of the cavity. The upper punch assembly includes an upper inner punch 201, an upper outer sleeve 202, and an upper inner punch drive 203.

[0078] The upper outer sleeve 202 has an upper outer sleeve cavity 2021, which penetrates the upper outer sleeve 202. The upper outer sleeve 202 consists of a first upper outer sleeve unit and a second upper outer sleeve unit. The first upper outer sleeve unit is located above the second upper outer sleeve unit. The first upper outer sleeve unit and the second upper outer sleeve unit are a single integrated structure. The outer diameter of the first upper outer sleeve unit is larger than the outer diameter of the second upper outer sleeve unit, forming an ear portion. The centerline of the upper outer sleeve cavity 2021 coincides with the centerline of the cavity 101. The length of the second upper outer sleeve unit is greater than the length of the female mold 1. The outer diameter of the second upper outer sleeve unit matches the diameter of the cavity 101.

[0079] A portion of the upper inner punch 201 is drilled into the upper outer sleeve cavity 2021. The upper inner punch 201 is vertically movable relative to the upper outer sleeve 202. The outer diameter of the upper inner punch 201 matches the diameter of the upper outer sleeve cavity 2021. The length of the upper inner punch 201 is greater than the length of the upper outer sleeve cavity 2021. The centerline of the upper inner punch 201 coincides with the centerline of the upper outer sleeve cavity 2021.

[0080] The upper inner punch drive 203 is connected to the top of the upper inner punch 201. The upper inner punch drive 203 and the upper inner punch 201 are an integrated structure. S2 is within the range of S1, and the centers of S1 and S2 coincide. S1 shows the projection of the upper inner punch drive 203 onto the horizontal plane. S2 shows the projection of the upper inner punch 201 onto the horizontal plane. The upper inner punch drive 203 can apply external pressure uniformly to the upper inner punch 201 and, in combination with the lugs of the upper outer sleeve 202, acts as a stopper for the upper inner punch 201.

[0081] The lower punch assembly includes a lower inner punch 301, a lower outer sleeve 302, and a lower outer sleeve drive 303.

[0082] At least a portion of the lower outer sleeve 302 is inserted into the cavity 101 from the lower end opening of the cavity. The lower outer sleeve 302 has a lower outer sleeve cavity 3021, which penetrates the lower outer sleeve 302. The lower outer sleeve 302 consists of a first lower outer sleeve unit and a second lower outer sleeve unit. The first lower outer sleeve unit is located below the second lower outer sleeve unit. The outer diameter of the first lower outer sleeve unit is larger than the outer diameter of the second lower outer sleeve unit, and it has lugs. The centerline of the lower outer sleeve cavity 3021 coincides with the centerline of the cavity 101. The length of the second lower outer sleeve unit is greater than the length of the female mold 1. The outer diameter of the second lower outer sleeve unit matches the diameter of the cavity 101. The diameter of the lower outer sleeve cavity 3021 is smaller than the diameter of the upper outer sleeve cavity 2021.

[0083] A portion of the lower internal punch 301 is drilled into the lower external sleeve cavity 3021. The lower internal punch 301 is vertically movable relative to the lower external sleeve 302. The outer diameter of the lower internal punch 301 matches the diameter of the lower external sleeve cavity 3021. The length of the lower internal punch 301 is greater than the length of the lower external sleeve cavity 3021. The centerline of the lower internal punch 301 coincides with the centerline of the lower external sleeve cavity 3021.

[0084] The lower internal punch drive 303 is connected to the bottom of the lower internal punch 301. The lower internal punch drive 303 and the lower internal punch 301 are an integrated structure. S4 is within the range of S3, and the centers of S3 and S4 coincide. S3 shows the projection of the lower internal punch drive 303 onto the horizontal plane. S4 shows the projection of the lower internal punch 301 onto the horizontal plane. The lower internal punch drive 303 can uniformly apply external pressure to the lower internal punch 301 and, in combination with the lugs of the lower external sleeve 302, acts as a stopper for the lower internal punch 301.

[0085] The diameters of the cavity, the upper outer sleeve cavity, and the lower outer sleeve cavity are shown in Table 1.

[0086] Table 1 TIFF2026059766000002.tif29170

[0087] Examples 4-5 The magnetic powder is subjected to hot pressing and hot deformation using a hot pressing and hot deformation apparatus, and the specific steps are as follows.

[0088] (1) Molybdenum disulfide, a mold release agent, was applied to the inner wall of the cavity 101 to be used, the inner wall of the upper outer sleeve cavity 2021, the outer surface of the upper inner punch 201, the inner wall of the lower outer sleeve cavity 3021, and the outer surface of the lower inner punch 301. The upper end of the lower outer sleeve 302 was positioned inside the cavity 101, and the lower inner punch 301 was moved away from the upper end of the lower outer sleeve 302. In this way, a first cavity was formed in the cavity 101 by the lower outer sleeve 302 and the lower inner punch 301. 80 g of neodymium iron boron rapidly solidified magnetic powder was placed inside the first cavity. The upper inner punch 201 and the bottom of the upper outer sleeve 202 were made flush, and the bottom of the upper inner punch 201 and the upper outer sleeve 202 were brought into contact with the upper end of the lower outer sleeve 302 to form the assembled device (shown in Figure 2).

[0089] The assembled device was placed inside the cavity of the heating equipment, the cavity of the heating equipment was evacuated, and argon gas was introduced. While maintaining the upper punch assembly, female mold 1, and lower outer sleeve 302 of the assembled device in a fixed position, the lower inner punch 301 was moved upward to apply pressure to the neodymium iron boron rapidly solidified magnetic powder and perform hot pressing to obtain a neodymium iron boron hot press blank 4.

[0090] (2) Referring to Figure 3, the upper inner punch 201 was moved upward, and the distance of movement may be the same as the height of the neodymium iron boron hot press blank 4, thereby forming a second cavity between the upper inner punch 201 and the upper outer sleeve 202. The lower inner punch 301 was moved upward so that the upper end of the lower inner punch 301 and the upper end of the lower outer sleeve 302 were flush, thereby causing the neodymium iron boron hot press blank 4 to enter the second cavity. While maintaining the lower punch assembly, female mold 1 and upper outer sleeve 202 in a fixed state, the upper inner punch 201 was moved downward to apply pressure to the neodymium iron boron hot press blank, causing preliminary deformation and forming a preliminary deformation blank 5.

[0091] (3) Referring to Figure 4, the upper outer sleeve 202 was moved upward so that the bottom of the upper outer sleeve 202 and the bottom of the upper inner punch 201 were flush. While maintaining that the bottom of the upper inner punch 201 and the bottom of the upper outer sleeve 202 were flush, and the top of the lower inner punch 301 and the top of the lower outer sleeve 302 were flush, the upper punch assembly and the lower punch assembly were moved at the same speed in the direction of the pre-deformed blank 5 to perform the final deformation and obtain the final deformed blank 6.

[0092] The upper punch assembly was moved to the outside of cavity 101, and the lower punch assembly was moved upward to push the ultimate deformed blank 6 out of cavity 101, and the temperature was lowered to 25°C to obtain a neodymium iron boron magnetic block.

[0093] The composition and process parameters of the neodymium iron boron rapidly solidified magnetic powder are shown in Table 2. The performance of the obtained neodymium iron boron magnetic block is shown in Table 3.

[0094] Table 2 TIFF2026059766000003.tif114170Note: The content of Pr in PrNd is 25 wt%, and the content of Nd is 75 wt%.

[0095] Comparative Example 1 Using the method of Example 4 of CN117116644A, hot pressing and hot deformation were performed on the same neodymium iron boron rapidly solidified magnetic powder as in Example 4 of the present application, and the performance of the obtained neodymium iron boron magnetic block is shown in Table 3.

[0096] Table 3 TIFF2026059766000004.tif35170

[0097] The present invention is not limited to the above embodiments, and any variations, improvements or alternatives that can be conceived by those skilled in the art without departing from the gist of the present invention shall be included in the scope of the present invention.

Claims

1. A hot pressing and hot deformation apparatus for magnetic powder, comprising a female mold, an upper punch assembly, and a lower punch assembly, The female mold has a cavity, and the cavity has an upper cavity opening and a lower cavity opening. The upper punch assembly includes an upper inner punch and an upper outer sleeve, the upper outer sleeve having an upper outer sleeve cavity, at least a portion of the upper inner punch being drilled within the upper outer sleeve cavity, the upper inner punch being set to move up and down relative to the upper outer sleeve, and the outer diameter of the upper inner punch matching the diameter of the upper outer sleeve cavity. A hot pressing and hot deformation apparatus for magnetic powder, characterized in that the lower punch assembly includes a lower inner punch and a lower outer sleeve, the lower outer sleeve having a lower outer sleeve cavity, at least a portion of the lower inner punch being drilled in the lower outer sleeve cavity, the lower inner punch being set to move up and down relative to the lower outer sleeve, the diameter of the lower outer sleeve cavity being smaller than the diameter of the upper outer sleeve cavity, and the outer diameter of the lower inner punch being the same as the diameter of the lower outer sleeve cavity.

2. The hot pressing and hot deformation apparatus for magnetic powder according to claim 1, characterized in that at least a portion of the upper outer sleeve has an outer diameter that matches the diameter of the cavity, and at least a portion of the lower outer sleeve has an outer diameter that matches the diameter of the cavity.

3. The hot pressing and hot deformation apparatus for magnetic powder according to claim 1, characterized in that the ratio of the diameter of the lower outer sleeve cavity to the diameter of the upper outer sleeve cavity is 1:(1.2 to 5.5), and the ratio of the diameter of the upper outer sleeve cavity to the diameter of the cavity is 1:(1.05 to 1.5).

4. A hot pressing and hot deformation apparatus for magnetic powder according to any one of claims 1 to 3, characterized in that the length of the upper inner punch is greater than or equal to the length of the upper outer sleeve cavity, the length of the lower inner punch is greater than or equal to the length of the lower outer sleeve cavity, and the length of the lower outer sleeve is greater than or equal to the length of the female mold.

5. A method for performing hot pressing and hot deformation of magnetic powder using a hot pressing and hot deformation apparatus described in any one of claims 1 to 4, Step (1) to obtain a neodymium iron boron hot press blank by applying pressure to neodymium iron boron magnetic powder by moving the lower inner punch upward while maintaining the upper punch assembly, female die, and lower outer sleeve of the assembled device in a fixed state, Step (1) describes an assembled device in which the upper end of the lower outer sleeve is located inside the cavity, the lower inner punch is separated from the upper end of the lower outer sleeve, a first cavity is formed inside the cavity by the lower outer sleeve and the lower inner punch, the first cavity contains neodymium iron boron magnetic powder, the upper inner punch and the bottom of the upper outer sleeve are flush, and the upper inner punch and the bottom of the upper outer sleeve are in contact with the upper end of the lower outer sleeve. Step (2) involves moving the upper inner punch upward so as to form a second cavity between the upper inner punch and the upper outer sleeve, and moving the lower inner punch upward so as to align the upper end of the lower inner punch with the upper end of the lower outer sleeve, thereby inserting the neodymium iron boron hot press blank into the second cavity, and while maintaining the lower punch assembly, female die, and upper outer sleeve in a fixed state, moving the upper inner punch downward to apply pressure to the neodymium iron boron hot press blank and pre-deform it, thereby obtaining a pre-deformed blank. Step (3) involves moving the upper outer sleeve upward so that the bottom of the upper outer sleeve is lower than the bottom of the upper inner punch, keeping the relative position of the upper outer sleeve and the upper inner punch constant, and while maintaining the top of the lower inner punch and the top of the lower outer sleeve flush, moving the upper punch assembly and the lower punch assembly in the direction of the pre-deformed blank to perform ultimate deformation and obtain a neodymium iron boron magnet. The method, including the method described above.

6. The method according to claim 5, characterized in that in step (1), hot pressing is performed in an inert atmosphere and at a temperature of 500 to 700°C; in step (2), preliminary deformation is performed in an inert atmosphere and at a temperature of 650 to 900°C; and in step (3), ultimate deformation is performed in an inert atmosphere and at a temperature of 750 to 950°C.

7. In step (1), the pressure applied to the neodymium iron boron magnetic powder is 100 to 500 MPa, and the holding time is 10 to 500 s. In step (2), the pressure applied to the neodymium iron boron hot press blank is 50 to 500 MPa, and the holding time is 1 to 100 s. The method according to claim 5, characterized in that, in step (3), the pressure applied to the pre-deformed blank is 80 to 600 MPa, and the holding time is 30 to 300 s.

8. The method according to claim 5, characterized in that in step (3), the speed at which the upper punch assembly moves in the pre-deformed blanking direction is 0.7 to 1.5 times the speed at which the lower punch assembly moves in the pre-deformed blanking direction.

9. The method according to claim 5, further comprising the steps of moving the upper punch assembly to the outside of the cavity, moving the lower inner punch and / or lower outer sleeve upward, thereby ejecting the ultimate deformation blank obtained by ultimate deformation from the cavity, and then cooling it to 20-35°C to obtain a neodymium iron boron magnet.

10. The method according to any one of claims 5 to 9, characterized in that the neodymium iron boron magnetic powder is neodymium iron boron rapidly solidified fine powder.

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