Forming die and forming method of composite powder material

Abstract

The invention relates to the technical field of powder metallurgy dies, in particular to a forming die and a forming method of a composite powder material. The forming die comprises a base, a lower punching assembly, a middle die, a lifting assembly and an upper punching assembly, and the lifting assembly is connected between the base and the middle die and used for driving the middle die to ascend and descend between a first height position filled with an outer-layer powder material and a second height position filled with an inner-layer powder material; and the molding requirements of various composite powder materials with different specifications can be met. Compared with a mold with a large number of special accessories and poor universality in the prior art, the mold can be flexibly applied to different products, the universality of the mold is greatly improved, and the mold is simple in structure and easy to operate. Due to the fact that the mold is high in universality, the mold can be suitable for various products, and the high cost of independently designing a special mold for each product is avoided. And meanwhile, the structure is simplified, so that the use of special accessories is reduced, and the manufacturing cost of the mold is further reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of powder metallurgy molds, and particularly to a forming mold and a forming method for composite powder materials. Background Art

[0002] In the field of modern part manufacturing, most parts exhibit a significant characteristic during actual use, that is, only some regions or parts need to have high service performance. Based on this characteristic, the application of double-layer or multi-layer materials has become an effective solution. Specifically, for regions or parts with high performance requirements, high-content alloy elements are used to meet the stringent service performance requirements; while for regions or parts with low performance requirements, alloy elements are used less or not at all, and they serve as the matrix to play a load-bearing role. This way can achieve the goals of economy and green manufacturing.

[0003] Among the numerous processes for manufacturing double-layer material parts, the powder metallurgy process has become the best manufacturing method due to its unique advantages. The powder metallurgy process can use two different powders to precisely meet the performance requirements of the high-performance area and the load-bearing area respectively. The forming processes of existing multi-layer composite material parts generally adopt a machine production mode, and the forming molds are all specially designed for specific models. This has led to a series of drawbacks: on the one hand, there are a large number of special accessories and the mold structure is complex, making the mold assembly work extremely difficult; on the other hand, the versatility of this special mold is extremely poor and it is difficult to be flexibly applied among different products. More prominently, the manufacturing cost of the mold is extremely high, which undoubtedly increases the economic burden of production.

[0004] Due to the above-mentioned various problems, the existing molds are only suitable for the stable production scenarios of mature products, and are extremely unsuitable for the research and development and experimental use of new products. In the research and development and experimental stages of new products, a more flexible, convenient and cost-controllable forming mold is needed. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] In view of the above-mentioned disadvantages and deficiencies of the prior art, the present invention provides a forming mold and a forming method for composite powder materials, which solve the technical problems that the forming operation of composite materials with different inner and outer layer materials is complex and costly during the research and development and experimental stages of new products.

[0007] (2) Technical Solutions

[0008] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0009] An embodiment of the present invention provides a forming die for a composite powder material, which includes a base, a lower punch assembly, a middle die, a lifting assembly, and an upper punch assembly; the lower punch assembly includes a lower outer punch and a lower inner punch that are coaxially sleeved and relatively slidable; the middle die is coaxially sleeved outside the lower outer punch, and the lifting assembly is connected between the base and the middle die for driving the middle die to lift between a first height position and a second height position; the upper punch assembly includes an upper outer punch and an upper inner punch that are coaxially sleeved and relatively slidable, the upper outer punch and the lower outer punch are arranged corresponding to each other up and down, and the upper inner punch and the lower inner punch are arranged corresponding to each other up and down; when the middle die is in the first height position, the top end of the lower inner punch extends upward beyond the top end of the lower outer punch to form an annular step, and the top end of the lower outer punch, the outer wall of the lower inner punch, and the inner wall of the middle die jointly enclose an annular die cavity for filling the outer layer powder material; when the middle die rises to the second height position, the top end of the lower inner punch and the inner wall of the upper outer punch jointly enclose a cylindrical die cavity for filling the inner layer powder material.

[0010] Preferably, the lifting assembly includes at least two sets of symmetrically arranged elastic reset units and limit posts; the top end of the elastic reset unit is connected to the bottom end of the middle die, and the bottom end of the elastic reset unit is connected to the base; the limit posts are vertically arranged on the base; when the middle die is pressed downward by an external force, the elastic reset unit compresses and stores energy, and the middle die moves downward and abuts against the top end of the limit post. At this time, the middle die is in the first height position; when the external force is removed, the elastic reset unit releases the elastic force to drive the middle die to move upward. At this time, the middle die is located at the second height position.

[0011] Preferably, the lifting assembly further includes a counterweight ring detachably installed on the top of the middle die; when the counterweight ring is installed on the middle die, the elastic reset unit compresses, and the middle die is located at the first height position; when the counterweight ring is removed, the elastic reset unit drives the middle die to be located at the second height position.

[0012] Preferably, the limit post is a first threaded rod; the top end of the first threaded rod is connected to the bottom end of the middle die, and the lower part of the first threaded rod is threadedly connected to the base.

[0013] Preferably, it further includes a telescopic member; one end of the telescopic member is connected to the base, and the other end of the telescopic member is connected to the lower inner punch to drive the top end of the lower inner punch to extend beyond the top end of the lower outer punch or be flush with the top end of the lower outer punch.

[0014] Preferably, the telescopic member is a second threaded rod; the top end of the second threaded rod is connected to the bottom end of the lower inner punch, and the lower part of the second threaded rod is threadedly connected to the base.

[0015] Preferably, a through groove is horizontally formed in the lower part of the lower outer punch.

[0016] Preferably, it further includes a jaw; the jaw is detachably arranged on the middle die; the jaw is hollowed out along the axial direction to make way for the formed composite powder material.

[0017] Preferably, the upper outer punch, the lower outer punch, and the middle die are all annular structures.

[0018] The present invention also provides a forming method for a composite powder material. Using the above-mentioned forming die, it includes the following steps;

[0019] S1. The lifting assembly drives the middle die to move to the first height position. The top end of the lower inner punch extends out of the top end of the lower outer punch and is flush with the top end of the middle die. The top end of the lower outer punch, the outer wall of the lower inner punch, and the inner wall of the middle die jointly enclose an annular die cavity;

[0020] S2. Fill the outer layer powder material in the annular die cavity;

[0021] S3. The upper outer punch moves downward and fits above the outer layer powder material in the annular die cavity;

[0022] S4. The lifting assembly drives the middle die to move to the second height position. The top end of the lower inner punch and the inner wall of the upper outer punch jointly enclose a cylindrical die cavity;

[0023] S5. Fill the inner layer powder material in the cylindrical die cavity;

[0024] S6. The lower inner punch moves downward until its top end is flush with the top end of the lower outer punch;

[0025] S7. The upper inner punch moves downward and fits above the inner layer powder material in the cylindrical die cavity;

[0026] S8. The upper outer punch and the upper inner punch move further downward simultaneously. The upper outer punch and the lower outer punch cooperate to extrude the outer layer powder material, and the upper inner punch and the lower inner punch cooperate to extrude the inner layer powder material. At this time, the outer layer powder material and the inner layer powder material jointly form a composite powder material.

[0027] (III) Beneficial effects

[0028] The beneficial effects of the present invention are:

[0029] A molding die for a composite powder material of the present invention includes a base, a lower punch assembly, a middle die, a lifting assembly, and an upper punch assembly. Due to the coaxially sleeved and relatively slidable lower outer punch and lower inner punch in the lower punch assembly and the coaxially sleeved and relatively slidable upper outer punch and upper inner punch in the upper punch assembly, the upper outer punch and the lower outer punch are arranged corresponding to each other vertically, and the upper inner punch and the lower inner punch are arranged corresponding to each other vertically. At the same time, since the lifting assembly is connected between the base and the middle die and is used to drive the middle die to lift between the first height position for filling the outer layer powder material and the second height position for filling the inner layer powder material, it can meet the molding requirements of a variety of different specifications of composite powder materials. Compared with the molds in the prior art with a large number of special accessories and poor versatility, this mold can be flexibly applied among different products, greatly improving the versatility of the mold, and has a simple structure and is easy to operate. Due to the strong versatility of the mold, it can be applied to a variety of products, avoiding the high cost of designing a dedicated mold for each product separately. At the same time, the simplification of the structure reduces the use of special accessories, further reducing the manufacturing cost of the mold.

[0030] A molding method for a composite powder material of the present invention can be flexibly applied among different products, greatly improving the versatility of the mold, and has a simple structure and is easy to operate. Brief Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of the molding die for the composite powder material of the present invention;

[0032] Figure 2 It is a front view of the molding die for the composite powder material;

[0033] Figure 3 It is a longitudinal sectional view of the molding die for the composite powder material;

[0034] Figure 4 It is a schematic structural diagram when the jaw is in use;

[0035] Figure 5 It is a sectional view showing that when the middle die is at the first height position, an annular die cavity is enclosed between the top of the lower outer punch, the outer wall of the lower inner punch, and the inner wall of the middle die;

[0036] Figure 6 It is a sectional view showing the filling of the outer layer powder material in the annular die cavity;

[0037] Figure 7 It is a sectional view showing that when the middle die is at the second height position, a cylindrical die cavity is enclosed between the top of the lower inner punch and the inner ring of the upper outer punch;

[0038] Figure 8 It is a sectional view showing the filling of the inner layer powder material in the cylindrical die cavity;

[0039] Figure 9Schematic cross-sectional view of the lower inner punch moving downward until its top is flush with the top of the lower outer punch;

[0040] Figure 10 Schematic cross-sectional view of the upper inner punch moving downward and fitting above the inner layer of powder material;

[0041] Figure 11 Schematic cross-sectional view of the forming of the composite powder material.

[0042]

Explanation of the reference numerals

[0043] 1: Base; 2: Lower punch assembly; 21: Lower outer punch; 22: Lower inner punch; 3: Middle die; 4: Lifting assembly; 41: Elastic reset unit; 42: Limit post; 43: Counterweight ring; 5: Upper punch assembly; 51: Upper outer punch; 52: Upper inner punch; 6: Telescopic member; 7: Claw; a: Annular die cavity; b: Cylindrical die cavity; c: Composite powder material. Detailed implementation manners

[0044] For better explaining the present invention for easy understanding, the present invention will be described in detail below in conjunction with the drawings through specific implementation manners.

[0045] Embodiment 1

[0046] As Figures 1-3 shown, the embodiment of the present invention provides a forming die for a composite powder material. The forming die includes a base 1, a lower punch assembly 2, a middle die 3, a lifting assembly 4 and an upper punch assembly 5. Among them, the lower punch assembly 2 includes a lower outer punch 21 and a lower inner punch 22 which are coaxially sleeved and relatively slidable, and the inner surface of the lower outer punch 21 is in contact with the outer surface of the lower inner punch 22. The upper punch assembly 5 includes an upper outer punch 51 and an upper inner punch 52 which are coaxially sleeved and relatively slidable. The upper outer punch 51 and the lower outer punch 21 are arranged corresponding to each other up and down, and the upper inner punch 52 and the lower inner punch 22 are arranged corresponding to each other up and down. When the upper inner punch 52 is located inside the upper outer punch 51, the outer surface of the upper inner punch 52 is in contact with the inner surface of the upper outer punch 51. The middle die 3 is coaxially sleeved outside the lower outer punch 21, and the lifting assembly 4 is connected between the base 1 and the middle die 3. The lifting assembly 4 is used to drive the middle die 3 to lift between a first height position for filling the outer layer of powder material and a second height position for filling the inner layer of powder material.

[0047] When the middle die 3 is in the first height position, the top end of the lower inner punch 22 extends upward beyond the top end of the lower outer punch 21 and is flush with the top end of the middle die 3 to form an annular step. The top end of the lower outer punch 21, the outer wall of the lower inner punch 22, and the inner wall of the middle die 3 jointly enclose an annular die cavity a for filling the outer layer of powder material. After filling the outer layer of powder material in the annular die cavity a, the upper outer punch 51 moves downward and fits against the top end of the outer layer of powder material. When the middle die 3 rises to the second height position, the top end of the lower inner punch 22 and the inner wall of the upper outer punch 51 jointly enclose a cylindrical die cavity b for filling the inner layer of powder material. After filling the inner layer of powder material in the cylindrical die cavity b, when the lower inner punch 22 moves downward until the top end of the lower inner punch 22 is flush with the top end of the lower outer punch 21, the upper inner punch 52 moves downward and fits against the top end of the inner layer of powder material. The upper inner punch 52 and the upper outer punch 51 simultaneously apply an external force to extrude and form the inner and outer layer powder materials.

[0048] The forming die provided in this embodiment can meet the forming requirements of a variety of composite powder materials c with different specifications. Compared with the die in the prior art that has a large number of special accessories and poor versatility, this die can be flexibly applied among different products, greatly improving the versatility of the die, and has a simple structure and is easy to operate. Due to the strong versatility of the die, it can be applied to a variety of products, avoiding the high cost of designing a special die for each product separately. At the same time, the simplification of the structure reduces the use of special accessories, further reducing the manufacturing cost of the die.

[0049] It should be noted that in this embodiment, the inner layer powder material and the outer layer powder material are different types of powders. The composite powder material c formed in this embodiment refers to the composite powder material c formed by the difference between the inner layer powder material and the outer layer powder material. The formed composite powder material c is a sheet-like structure in which the inner layer powder material and the outer layer powder material are tightly connected.

[0050] As Figure 2 and Figure 3 shown, the lifting assembly 4 includes at least two groups of symmetrically arranged elastic reset units 41 and limit posts 42. The top end of the elastic reset unit 41 is connected to the bottom end of the middle die 3, the bottom end of the elastic reset unit 41 is connected to the base 1, and the limit posts 42 are vertically arranged on the base 1. When the middle die 3 is pressed downward by an external force, the elastic reset unit 41 compresses and stores energy, causing the middle die 3 to move downward and abut against the top end of the limit post 42. At this time, the middle die 3 is in the first height position; when the external force is removed, the elastic reset unit 41 releases the elastic force to drive the middle die 3 to move upward. At this time, the middle die 3 is located at the second height position. In this embodiment, the elastic reset unit 41 is a spring, and the limit post 42 is a first threaded rod. The top end of the first threaded rod is connected to the bottom end of the middle die 3, and the lower part of the first threaded rod is threadedly connected to the base 1. The height of the top end of the first threaded rod can be adjusted according to actual needs, that is, the height of the first height position of the middle die 3 can be adjusted, which is also convenient for the subsequent removal of the composite powder material c and for descending to make way.

[0051] Among them, to facilitate the application of a continuous external force to the middle mold 3, the lifting assembly 4 further includes a counterweight ring 43 detachably installed on the top of the middle mold 3. The inner diameter of the counterweight ring 43 is larger than that of the middle mold 3 to avoid interference during the filling of the powder material. When the counterweight ring 43 is installed on the middle mold 3, the elastic reset unit 41 is compressed, and the middle mold 3 is located at the first height position. When the counterweight ring 43 is removed, the elastic reset unit 41 drives the middle mold 3 to be located at the second height position.

[0052] To facilitate the adjustment of the height of the lower inner punch 22, the forming mold further includes a telescopic member 6. One end of the telescopic member 6 is connected to the base 1, and the other end of the telescopic member 6 is connected to the lower inner punch 22 to drive the top end of the lower inner punch 22 to extend out of the top end of the lower outer punch 21 or be flush with the top end of the lower outer punch 21. Among them, the telescopic member 6 is a second threaded rod. The top end of the second threaded rod is connected to the bottom end of the lower inner punch 22, and the lower part of the second threaded rod is threadedly connected to the base 1. To facilitate the manual adjustment of the second threaded rod, a through groove is horizontally opened in the lower part of the lower outer punch 21 to facilitate inserting into the through groove to adjust the second threaded rod.

[0053] As Figure 4 shown, the forming mold further includes a jaw 7. The jaw 7 is detachably arranged on the middle mold 3. When it is necessary to take out the formed composite powder material c, the upper punch assembly 5 is removed, the first threaded rod is adjusted downward, the jaw 7 is installed, and the jaw 7 is pressed downward. The jaw 7 is hollowed out along the axial direction to make way for the formed composite powder material c.

[0054] It should be noted that the upper outer punch 51, the lower outer punch 21, and the middle mold 3 are all annular structures, and can be set into other shape structures such as circular or rectangular according to actual needs. Of course, correspondingly, the upper outer punch 51 cooperates with the lower outer punch 21, and the upper inner punch 52 cooperates with the lower inner punch 22.

[0055] Embodiment 2

[0056] As Figures 5-11 shown, this embodiment provides a forming method for a composite powder material, using the forming mold in Embodiment 1, including the following steps;

[0057] S1. Adjust the height of the first threaded rod in the lifting assembly 4, place the counterweight ring 43, and the middle mold 3 descends and abuts against the top end of the first threaded rod. At this time, the middle mold 3 is located at the first height position. Adjust the height of the second threaded rod so that the top end of the lower inner punch 22 extends out of the top end of the lower outer punch 21 and is flush with the top end of the middle mold 3. The top end of the lower outer punch 21, the outer wall of the lower inner punch 22, and the inner wall of the middle mold 3 jointly enclose an annular mold cavity a;

[0058] S2. Fill the outer layer powder material in the annular mold cavity a;

[0059] S3. The upper outer punch 51 moves downward and fits above the outer layer of powder material within the annular die cavity a;

[0060] S4. Remove the counterweight ring 43 in the lifting component 4, and the elastic reset unit 41 drives the middle die 3 to the second height position. At this time, the top of the lower inner punch 22 and the inner wall of the upper outer punch 51 jointly enclose a cylindrical die cavity b;

[0061] S5. Fill the inner layer of powder material into the cylindrical die cavity b;

[0062] S6. The lower inner punch 22 moves downward until its top is flush with the top of the lower outer punch 21;

[0063] S7. The upper inner punch 52 moves downward and fits above the inner layer of powder material within the cylindrical die cavity b;

[0064] S8. Move the molding die to the stamping machine, apply a large external force to the upper outer punch 51 and the upper inner punch 52, so that the upper outer punch 51 and the upper inner punch 52 move further downward simultaneously. The upper outer punch 51 and the lower outer punch 21 cooperate to extrude the outer layer of powder material, and the upper inner punch 52 and the lower inner punch 22 cooperate to extrude the inner layer of powder material. At this time, the outer layer of powder material and the inner layer of powder material are tightly connected to jointly form a composite powder material c.

[0065] The molding method of a composite powder material of the present invention can be flexibly applied among different products, greatly improving the versatility of the die, and having a simple structure and easy operation.

[0066] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0067] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "connected to", "fixed" and other terms should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium; it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0068] In the present invention, unless otherwise clearly specified or limited, a first feature being "on" or "under" a second feature may mean that the first and second features are in direct contact, or the first and second features are indirectly in contact via an intermediate medium. Moreover, a first feature being "above", "over" and "on top of" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. A first feature being "under", "below" and "beneath" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the horizontal height of the first feature is lower than that of the second feature.

[0069] In the description of this specification, the descriptions of terms such as "an embodiment", "some embodiments", "embodiments", "examples", "specific examples" or "some examples", etc. refer to that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0070] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A molding die for composite powder material, characterized in that: It comprises a base (1), a lower punch assembly (2), a middle die (3), a lifting assembly (4) and an upper punch assembly (5); The lower punch assembly (2) comprises a lower outer punch (21) and a lower inner punch (22) which are coaxially sleeved and can slide relative to each other; The middle die (3) is coaxially sleeved on the outer side of the lower outer punch (21), and the lifting assembly (4) is connected between the base (1) and the middle die (3) and is used to drive the middle die (3) to rise and fall between a first height position and a second height position; The upper punch assembly (5) comprises an upper outer punch (51) and an upper inner punch (52) which are coaxially sleeved and can slide relative to each other, the upper outer punch (51) and the lower outer punch (21) are arranged in a vertically corresponding manner, and the upper inner punch (52) and the lower inner punch (22) are arranged in a vertically corresponding manner; When the middle die (3) is at a first height position, the top end of the lower inner punch (22) extends upward from the top end of the lower outer punch (21) to form an annular step, and the top end of the lower outer punch (21), the outer wall of the lower inner punch (22) and the inner wall of the middle die (3) together form an annular die cavity (a) for filling the outer layer powder material; When the middle die (3) rises to a second height position, the top end of the lower inner punch (22) and the inner wall of the upper outer punch (51) together form a cylindrical die cavity (b) for filling the inner layer powder material.

2. The forming die for composite powder material according to claim 1, characterized in that: The lifting assembly (4) comprises at least two groups of symmetrically arranged elastic reset units (41) and limiting columns (42); The top end of the elastic reset unit (41) is connected to the bottom end of the middle mold (3), and the bottom end of the elastic reset unit (41) is connected to the base (1); The limiting column (42) is vertically arranged on the base (1); When the middle mold (3) is pressed downward by an external force, the elastic reset unit (41) compresses and stores energy and causes the middle mold (3) to move downward and abut against the top of the limiting column (42), and at this time the middle mold (3) is at the first height position; When the external force is released, the elastic reset unit (41) releases the elastic force to drive the middle mold (3) to move upward, and at this time the middle mold (3) is located at the second height position.

3. The forming die for composite powder material according to claim 2, characterized in that: The lifting assembly (4) further comprises a counterweight ring (43) detachably mounted on the top of the middle mold (3); When the counterweight ring (43) is installed on the middle mold (3), the elastic reset unit (41) is compressed and the middle mold (3) is located at the first height position; When the counterweight ring (43) is removed, the elastic reset unit (41) drives the middle mold (3) to be located at the second height position.

4. The forming die for composite powder material according to claim 2, characterized in that: The limiting column (42) is a first threaded rod; The top end of the first threaded rod is connected to the bottom end of the middle mold (3), and the lower part of the first threaded rod is threadedly connected to the base (1).

5. The forming die for composite powder material according to claim 1, characterized in that: It also includes a telescopic member (6); One end of the telescopic member (6) is connected to the base (1), and the other end of the telescopic member (6) is connected to the lower inner punch (22) to drive the top end of the lower inner punch (22) to extend out of the top end of the lower outer punch (21) or to be flush with the top end of the lower outer punch (21).

6. The forming die for composite powder material according to claim 5, characterized in that: The telescopic member (6) is a second threaded rod; The top end of the second threaded rod is connected to the bottom end of the lower inner punch (22), and the lower part of the second threaded rod is threadedly connected to the base (1).

7. The forming die for composite powder material according to claim 1, characterized in that: The lower portion of the lower outer punch (21) is provided with a through groove in the horizontal direction.

8. The forming die for composite powder material according to claim 1, characterized in that: Also includes a clamping claw (7); The clamping claw (7) is detachably arranged on the middle mold (3); The clamping jaw (7) is hollowed out along the axial direction to make room for the formed composite powder material (c).

9. The forming die for composite powder material according to claim 1, characterized in that: The upper outer punch (51), the lower outer punch (21) and the middle die (3) are all annular structures.

10. A method for forming a composite powder material, characterized in that: Using the molding die according to any one of claims 1 to 9, comprising the following steps: S1, the lifting assembly (4) drives the middle die (3) to move to the first height position, the top end of the lower inner punch (22) extends out of the top end of the lower outer punch (21) and is flush with the top end of the middle die (3), and the top end of the lower outer punch (21), the outer wall of the lower inner punch (22) and the inner wall of the middle die (3) together form the annular die cavity (a); S2, filling the annular mold cavity (a) with an outer layer of powder material; S3, the upper outer punch (51) moves downward and fits above the outer layer of powder material in the annular die cavity (a); S4, the lifting assembly (4) drives the middle mold (3) to move to the second height position, and the top end of the lower inner punch (22) and the inner wall of the upper outer punch (51) together form the cylindrical mold cavity (b); S5, filling the inner layer powder material into the cylindrical mold cavity (b); S6, the lower inner punch (22) moves downward until its top end is flush with the top end of the lower outer punch (21); S7, the upper inner punch (52) moves downward and fits above the inner layer of powder material in the cylindrical mold cavity (b); S8. The upper outer punch (51) and the upper inner punch (52) are moved further downward at the same time, and the upper outer punch (51) cooperates with the lower outer punch (21) to extrude the outer layer powder material, and the upper inner punch (52) cooperates with the lower inner punch (22) to extrude the inner layer powder material. At this time, the outer layer powder material and the inner layer powder material together form a composite powder material (c).

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