A preform, a composite component based on a preform and a drawing method

Abstract

The application discloses a preform, a composite component based on the preform and a drawing forming method, and belongs to the technical field of dissimilar metal composite forming. An outer cladding layer with a closed end and a containing cavity is prepared, a core rod with an interface bonding structure arranged on the outer periphery is prepared, and a preformed bimetallic blank is assembled; a structure of a ring-shaped connecting sleeve end face main force transmission and a pin shaft auxiliary limiting is used to realize the connection of a compression rod and the core rod, coaxial positioning of the blank is realized through a drawing hole entrance; the outer cladding layer is plastically flowed under radial compression in a composite drawing forming area, the interface bonding structure is completely filled and coated, and a mechanical interlocking bonding interface is formed. The application is suitable for various outer cladding layer preparation processes, can reduce material loss, improve load transmission stability and positioning accuracy, enhance interface bonding strength and component service reliability, and is suitable for preparation of various shaft rod type bimetallic composite components.

Description

Technical Field

[0001] This invention relates to the field of dissimilar metal composite forming technology, and in particular to a preform, a composite component based on the preform, and a drawing forming method. Background Technology

[0002] Bimetallic composite components combine the electrical conductivity, thermal conductivity, corrosion resistance, and wear resistance of two metals with the load-bearing properties of high strength and high rigidity, making them widely used in industrial applications such as conductive connectors, load-bearing rods, and composite shafts. Drawing forming, which alters the cross-sectional dimensions of the blank under the combined action of axial load and radial constraint, offers excellent forming continuity and high dimensional accuracy, making it one of the mainstream manufacturing processes for bimetallic composite components.

[0003] Existing bimetallic drawing technology has several shortcomings: First, the outer cladding layer is mostly made by drilling and boring the inner hole of a solid blank, resulting in large material removal, high processing costs, and difficulty in adapting to low-cost manufacturing processes such as extrusion and casting, leading to poor process flexibility. Second, the bimetallic interface is mostly a smooth structure, relying solely on radial compression and interfacial friction for bonding, making it prone to relative slippage under axial and torsional loads. Even with surface concave-convex structures, insufficient radial flow of the outer cladding layer material often results in incomplete filling of concave areas and incomplete coverage of convex areas. The problems are as follows: First, gaps exist at the interface, limiting the mechanical interlocking effect; second, the pressure bar and mandrel mostly use pins as the main force transmission components, and the load is concentrated in the local area of ​​the connecting hole, which can easily cause deformation of the connecting hole, shear failure of the pin, and uneven loading of the mandrel; third, the blank lacks effective radial positioning before entering the drawing hole, which can easily lead to defects such as eccentric entry, uneven wall thickness, and uneven interface bonding; fourth, large deformation in a single pass can easily cause cracking of the outer coating layer and mandrel displacement, and the forming scheme with multiple process combinations is not adaptable enough to adapt to the combination of dissimilar metals with large differences in plasticity.

[0004] Therefore, there is an urgent need for a bimetallic drawing method that is compatible with various outer coating preparation processes, has stable load transfer, high entry positioning accuracy, and excellent interfacial bonding strength. Summary of the Invention

[0005] To address the technical problems of localized stress concentration at the axial load transfer points, insufficient interface structure filling, and inadequate mechanical interlocking in the existing bimetallic composite drawing process, this invention provides a preform, a composite component based on the preform, and a drawing forming method.

[0006] The technical solution adopted by the present invention, including a preform, a composite component based on the preform, and a drawing forming method, is as follows:

[0007] A method for drawing composite components based on preformed blanks includes the following steps:

[0008] S1. Prepare an outer cladding layer made of a first metallic material, wherein the outer cladding layer is a shell structure that is closed at one end, open at the other end, and has a receiving cavity; prepare a mandrel made of a second metallic material different from the first metallic material, wherein the mandrel includes a forming mating section and a connecting boss, wherein a connecting hole is provided on the connecting boss, and an interface bonding structure is formed on the outer peripheral surface of the forming mating section;

[0009] S2. Insert the forming fitting section into the receiving cavity from the open end, so that the end of the mandrel located in the receiving cavity contacts the inner side of the closed end of the outer covering layer, so as to form an axial force transmission relationship between the mandrel and the outer covering layer that can transmit axial forming load, and the connecting boss extends out of the open end of the outer covering layer to obtain a pre-made bimetallic blank.

[0010] S3. The annular force transmission connection structure between the connecting boss and the end of the pressure rod is made into a detachable connection.

[0011] S4. Orient the closed end of the pre-made bimetallic billet toward the forming hole inlet of the drawing die, and radially limit the outer coating layer through the forming hole inlet to make the billet coaxially positioned at the inlet; apply an axial forming load to the mandrel through the pressure bar to drive the pre-made bimetallic billet through the composite drawing forming zone, so that the outer coating layer undergoes plastic flow under radial compression constraint, completely filling the concave part of the interface bonding structure and completely covering its protruding part, forming a mechanically interlocked bonding interface between the bimetals, and obtaining a bimetallic composite component.

[0012] A further improvement of the technical solution of the present invention is that: the outer coating layer is prepared by one or more processes of extrusion molding, casting molding, and machining; the connecting boss and the forming mating section of the mandrel are preferably an integral structure, the cross-sectional dimension of the connecting boss is smaller than that of the forming mating section, and a mandrel end face is formed at the root of the connecting boss for contacting the annular connecting sleeve and transmitting axial forming load.

[0013] A further improvement of the technical solution of the present invention is that: the interface bonding structure includes one or more combinations of toothed groove structure, pit structure, protrusion structure, and knurling structure; the toothed groove structure includes annular toothed groove or spiral toothed groove; the pit structure and the protrusion structure are distributed along the axial and / or circumferential direction of the mandrel; and the knurling structure includes straight knurling, oblique knurling, or mesh knurling structure.

[0014] A further improvement of the technical solution of the present invention is that: the annular force transmission connection structure includes an annular connecting sleeve and a pin; the annular connecting sleeve is disposed at the end of the pressure rod, and a connecting cavity for the insertion of the connecting boss is formed inside; after assembly, the end face of the annular connecting sleeve fits against the end face of the mandrel at the root of the connecting boss, forming the main force transmission contact surface; the pin passes through the connecting hole of the annular connecting sleeve and the connecting boss along the axis perpendicular to the mandrel, and is used to maintain the detachable connection and restrict the axial separation of the two.

[0015] A further improvement of the technical solution of the present invention is that the coaxial positioning state of the inlet is achieved by the matching and cooperation between the contour of the forming hole inlet and the outer periphery of the outer covering layer, which is used to limit the radial offset of the prefabricated bimetallic billet and ensure that the entry position of the billet corresponds coaxially with the forming hole.

[0016] A further improvement of the technical solution of the present invention is that: the composite drawing forming zone includes a plurality of drawing rings arranged sequentially along the forming direction for preliminary diameter reduction and radial pre-compression of the blank, and a plurality of roller dies located after the drawing rings for continuously applying radial compression constraints to promote complete filling of the outer coating material and bonding with the coating interface.

[0017] A further improvement of the technical solution of the present invention is that: after the bimetallic composite component is obtained, the pin is removed to separate the pressure rod from the mandrel; the connecting boss is completely removed, partially removed, or completely retained, and the retained part is used to process to form an assembly connection structure, a positioning structure, or a clamping structure.

[0018] A preform for the above-mentioned drawing forming method includes an outer cladding layer made of a first metal material and a mandrel made of a second metal material different from the first metal material; the outer cladding layer is a shell structure with one end closed and the other end open and having a receiving cavity; the mandrel includes a forming mating section located in the receiving cavity and a connecting boss extending from the open end, the connecting boss being provided with a connecting hole, and the outer peripheral surface of the forming mating section being provided with an interface bonding structure; one end of the mandrel located in the receiving cavity contacts the inner side of the closed end of the outer cladding layer to form an axial force transmission relationship capable of transmitting axial forming loads; the connecting boss is used to insert an annular connecting sleeve at the end of the pressure bar and forms a detachable connection with the annular connecting sleeve through a pin.

[0019] A composite component based on a preform for use in the above-mentioned drawing forming method includes a mandrel and an outer covering layer covering its outer periphery; the outer periphery of the mandrel is provided with an interface bonding structure, and the material of the outer covering layer completely fills the recessed part of the interface bonding structure and completely covers its protruding part, forming a mechanically interlocked bonding interface between the two.

[0020] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:

[0021] The outer coating of this invention adopts a shell structure with one end closed, which can be prepared by various methods such as extrusion, casting, and machining, reducing material loss during machining and adapting to different production conditions and material cost requirements.

[0022] In this invention, the axial forming load is transmitted to the mandrel through the contact area between the annular connecting sleeve and the end face of the mandrel. The pin is mainly used to maintain the connection between the annular connecting sleeve and the connecting boss and to limit axial separation, thereby increasing the load transmission area of ​​the end face, reducing the risk of local load concentration and off-center load, and forming a complete and stable axial force transmission path for the outer coating layer of the mandrel.

[0023] This invention achieves radial limiting and coaxial positioning of the billet through the drawing hole inlet contour, avoiding defects such as uneven wall thickness and uneven interface bonding caused by eccentric entry from the source; the outer coating material of this invention completely fills and covers the interface bonding structure under continuous radial compression, improves the filling degree of the interface bonding structure, forms a stable mechanical interlocking interface, and improves the component's resistance to axial slippage and torsion.

[0024] This invention can flexibly adopt multi-pass drawing or drawing-roller die combination process, reasonably allocate the deformation amount at each stage, reduce the risk of outer coating cracking and mandrel displacement, and adapt to dissimilar metal combinations with large differences in plasticity. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating the process principle of a composite component drawing method based on preformed blanks according to the present invention.

[0026] Figure 2 This is a schematic diagram of the structure of the outer coating layer and the core rod of the present invention;

[0027] Figure 3 This is an assembly diagram of the precast blank, annular connecting sleeve, and pin connection structure of the present invention.

[0028] In the attached diagram: 1. Outer covering layer; 11. Closed end; 12. Side wall; 13. Receiving cavity; 14. Open end;

[0029] 2. Mandrel; 21. Forming and mating section; 22. Connecting boss; 221. Connecting hole; 23. Interface bonding structure;

[0030] 3. Pre-fabricated bimetallic billet; 4. Drawing ring; 41. Drawing hole; 5. Roller die; 6. Pressure bar; 61. Annular connecting sleeve; 62. Pin shaft; 7. Bimetallic composite component; 71. Mechanical interlocking interface; 8. Forming direction. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of this invention.

[0032] like Figures 1-3 As shown in the figure, the specific implementation process of the composite component drawing forming method based on preformed blanks provided in this embodiment is as follows:

[0033] S1. Preparation of preformed billets

[0034] S1.1, Preparation of outer coating layer: The outer coating layer 1 is made of a first metal material and is a shell structure with one end closed and the other end open, including a closed end 11, a side wall 12, a receiving cavity 13 and an open end 14. The closed end 11 and the side wall 12 are integrally formed to form a receiving cavity 13 that communicates with the open end 14.

[0035] The preparation process of the outer coating layer 1 can be flexibly selected according to the material properties and production conditions:

[0036] (1) When reverse extrusion forming is used, the punch extrudes the blank and the metal flows plastically in the opposite direction of the punch movement, directly forming a shell structure with a closed end. The material utilization rate is high and it is suitable for mass production.

[0037] (2) When casting is used, the shell structure is formed by integrally molding the mold and the core. After demolding, the inner hole, outer circle and end face can be machined to improve the dimensional accuracy.

[0038] (3) When machining, the solid blank is drilled and bored to form a cavity 13, and the bottom material is retained as a closed end 11, which is suitable for small batch high precision scenarios.

[0039] The above processes can be used individually or in combination of two or more methods to balance forming efficiency, material utilization and dimensional accuracy.

[0040] S1.2 Mandrel Preparation: The mandrel 2 is made of a second metal material different from the first metal material, and includes a forming mating section 21 and a connecting boss 22, which are integral structures. The cross-sectional dimension of the connecting boss 22 is smaller than that of the forming mating section 21, thus forming an annular mandrel end face at the root of the connecting boss 22. This end face is the main transmission surface for axial load. A connecting hole 221 perpendicular to the mandrel axis is provided on the connecting boss 22, and the connecting hole 221 penetrates the connecting boss 22 radially.

[0041] The interface 23 on the outer peripheral surface of the forming and fitting section 21 can be machined using one or more of the following forms and combinations:

[0042] (1) Gear structure: including annular gears that extend circumferentially and are spaced apart axially, or spiral gears that extend spirally along the outer periphery. The cross-sectional profile can be rectangular, trapezoidal, triangular or sawtooth. The annular gears mainly restrict axial relative slippage, while the spiral gears can restrict both axial slippage and circumferential rotation.

[0043] (2) Concave structure: Multiple independent concaves are distributed at intervals along the axial and circumferential directions. The opening of the concave can be circular or elliptical, and the bottom of the concave can be arc-shaped, conical or cylindrical.

[0044] (3) Protruding structure: Multiple columnar, conical, hemispherical or strip-shaped protrusions are distributed at intervals along the axial and circumferential directions.

[0045] (4) Knurling structure: It consists of alternating knurling ridges and knurling grooves, including straight knurling, oblique knurling or mesh knurling, which are formed by rolling or cutting.

[0046] Before assembly, the inner surface of the outer covering layer 1 and the outer surface of the core rod 2 can be pre-treated by grinding, sandblasting, degreasing, removing oxide layer, drying, etc., to improve the interface bonding quality and bonding effect.

[0047] S2. Blank Assembly: The forming fitting section 21 of the mandrel 2 is inserted into the receiving cavity 13 from the open end 14 of the outer covering layer 1, so that the inner end face of the mandrel 2 is in close contact with the inner side of the closed end 11 of the outer covering layer 1, forming a stable axial force transmission fit; at the same time, the connecting boss 22 extends outward from the open end 14, finally obtaining the pre-made bimetallic blank 3. The forming fitting section 21 and the receiving cavity 13 can adopt a clearance fit or a transition fit, taking into account both assembly convenience and initial positioning stability.

[0048] S3, Force transmission structure connection and inlet positioning

[0049] An annular connecting sleeve 61 is fixed to the end of the pressure rod 6. The interior of the annular connecting sleeve 61 is a connecting cavity adapted to the connecting boss 22, and pin holes corresponding to the positions of the connecting holes 221 are opened on the side walls on opposite sides. The annular connecting sleeve 61 can be integrally formed with the pressure rod 6, or it can be fixed to the end of the pressure rod 6 by welding, threaded connection or fastener connection.

[0050] During assembly, the connecting boss 22 is inserted into the connecting cavity of the annular connecting sleeve 61, ensuring that the front end face of the annular connecting sleeve 61 is tightly fitted with the end face of the mandrel at the root of the connecting boss 22. Then, the pin 62 is passed sequentially through the pin hole on one side, the connecting hole 221, and the pin hole on the other side of the annular connecting sleeve 61 in a direction perpendicular to the mandrel's axial direction, completing the detachable connection. The pin 62 can be a cylindrical pin, a quick-release pin, or other similar type, and an anti-detachment structure can be provided at its end.

[0051] In this connection structure, the main axial forming load is transmitted to the mandrel 2 through the contact surface between the annular connecting sleeve 61 and the end face of the mandrel. The force transmission area is large and the stress distribution is uniform. The pin 62 only serves as a connection limit to prevent the pressure rod 6 from separating axially from the mandrel 2, thus avoiding the deformation and shear failure problems caused by the main load being concentrated on the pin and the connecting hole.

[0052] S4, Composite drawing forming

[0053] During inlet positioning, the closed end 11 of the pre-made bimetallic billet 3 is oriented towards the inlet of the drawing hole 41 of the drawing ring 4, and the closed end 11 is placed into the inlet of the drawing hole 41. The contour and size of the inlet of the drawing hole 41 are adapted to the outer periphery of the outer cladding layer 1, which can form a radial limit on the outer cladding layer 1, restricting the radial displacement of the billet, and keeping the billet axis coaxial with the axis of the drawing hole 41, that is, the inlet coaxial positioning state, avoiding uneven wall thickness and uneven interface bonding caused by eccentric entry.

[0054] The order of force transmission structure connection and inlet positioning operations can be adjusted according to the on-site working conditions, or they can be carried out simultaneously.

[0055] The pressure bar 6 applies an axial forming load along the forming direction 8. The load is transmitted to the mandrel 2 through the annular connecting sleeve 61 and the end face of the mandrel, and then transmitted to the outer coating layer 1 through the contact surface between the inner end of the mandrel 2 and the closed end 11, pushing the pre-made bimetallic billet 3 through the composite drawing forming zone as a whole.

[0056] The composite drawing forming zone can be configured in various ways:

[0057] A. Single drawing ring type: Only one drawing ring 4 is set, which is suitable for scenarios with small deformation and good material plasticity.

[0058] B. Multiple drawing ring type: Multiple drawing rings 4 are set along the forming direction 8. The diameter of each drawing ring is gradually reduced to achieve gradual diameter reduction, reduce the amount of deformation per pass, and reduce the risk of cracking of the outer coating and mandrel displacement.

[0059] C. Drawing ring + roller die combination: At least one drawing ring 4 is first set along the forming direction 8, and then at least one roller die 5 is set; the drawing ring 4 completes the initial diameter reduction and radial pre-compression, and the roller die 5 is composed of multiple circumferentially arranged rollers, forming roller die holes between the rollers. Radial compression is continuously applied through the rolling extrusion of the rollers, while reducing the relative sliding friction between the blank and the die, promoting the full flow of the outer coating material, and completely filling the recessed part of the interface bonding structure.

[0060] During the process of passing through the composite drawing forming zone, the outer cladding layer 1 is subjected to continuous radial compression, and the metal undergoes plastic flow towards the mandrel 2: for the toothed structure, the material completely fills the groove and covers the exposed surface of the tooth; for the recessed structure, the material completely fills each recess; for the protruding structure, the material fills the gap between the protrusions and covers the exposed surface of the protrusions; for the knurled structure, the material completely fills the knurled groove and covers the knurled ridge surface. Finally, a continuous, gapless mechanically interlocked interface 71 is formed between the outer cladding layer 1 and the mandrel 2, resulting in a bimetallic composite component 7.

[0061] Composite drawing can be performed at room temperature or under warm conditions. Lubricant can be applied to the contact area between the die and the blank to reduce forming resistance and surface damage.

[0062] After forming, the pin 62 is pulled out, so that the annular connecting sleeve 61 is separated from the connecting boss 22, and the pressure rod 6 is demolded from the component.

[0063] Depending on the usage requirements of the component, the connecting boss 22 can be processed as follows: it can be completely removed as a process allowance to form a flat end face at the end of the mandrel; it can be partially removed and then processed with threads, connecting holes, etc., to form an assembly connection structure; or it can be completely retained and used as a positioning structure or clamping structure.

[0064] In this embodiment, the first metal material can be copper, aluminum, nickel and their alloys, which have good plasticity, and the second metal material can be steel, stainless steel, titanium alloy and other materials with high strength, so that the component has both the functional characteristics of the outer layer and the load-bearing capacity of the core.

[0065] In the above embodiments, a preform, a composite component based on the preform, and a drawing forming method are provided. The outer cladding layer of the present invention adopts a shell structure with one end closed, which can be prepared by various methods such as extrusion, casting, and machining, reducing material loss during machining and adapting to different production conditions and material cost requirements. The present invention adopts a connection method with the end face of the annular connecting sleeve as the main force transmission and the pin shaft as the auxiliary limiting, increasing the force transmission area, reducing the risk of local stress concentration and off-center load, and forming a complete and stable axial force transmission path of pressure bar-mandrel-outer cladding layer. The present invention achieves radial limiting and coaxial positioning of the blank through the drawing hole inlet contour, avoiding defects such as uneven wall thickness and uneven interface bonding caused by eccentric entry from the source. The outer cladding layer material of the present invention completely fills and covers the interface bonding structure under continuous radial compression, forming a gapless mechanical interlocking interface, improving the component's resistance to axial slippage and torsion. The present invention can flexibly adopt multi-pass drawing or drawing-roller die combination process, reasonably allocate the deformation amount at each stage, reduce the risk of outer cladding layer cracking and mandrel displacement, and adapt to the combination of dissimilar metals with large differences in plasticity.

[0066] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the inventive concept should fall within the protection scope of the present invention. All technical contents for which protection is sought in this invention are fully described in the claims.

Claims

1. A method for drawing composite components based on precast blanks, characterized in that, Includes the following steps: S1. Prepare an outer cladding layer (1) made of a first metal material, wherein the outer cladding layer (1) is a shell structure that is closed at one end and open at the other end and has a receiving cavity (13); prepare a core rod (2) made of a second metal material different from the first metal material, wherein the core rod (2) includes a forming mating section (21) and a connecting boss (22), wherein a connecting hole (221) is provided on the connecting boss (22), and an interface bonding structure (23) is formed on the outer peripheral surface of the forming mating section (21). S2. Insert the forming section (21) into the receiving cavity (13) from the open end (14), so that one end of the mandrel (2) located in the receiving cavity (13) contacts the inner side of the closed end of the outer covering layer (1), so as to form an axial force transmission relationship between the mandrel (2) and the outer covering layer (1) that can transmit axial forming load. The connecting boss (22) extends out of the open end (14) of the outer covering layer (1) to obtain the pre-made bimetallic blank (3). S3. Form a detachable connection between the connecting boss (22) and the end of the pressure rod (6) with the annular force transmission connection structure; S4. Orient the closed end of the pre-made bimetallic blank (3) toward the forming hole inlet of the drawing die, and radially limit the outer covering layer (1) through the forming hole inlet, so that the blank is in the coaxial positioning state of the inlet; Apply an axial forming load to the mandrel (2) through the pressure rod (6), drive the pre-made bimetallic blank (3) through the composite drawing forming zone, so that the outer covering layer (1) undergoes plastic flow under radial compression constraint, completely fills the recessed part of the interface bonding structure (23) and completely covers its protruding part, forming a mechanical interlocking bonding interface (71) between the bimetals, and obtain the bimetallic composite component (7).

2. The method for drawing composite components based on precast blanks according to claim 1, characterized in that: The outer covering layer (1) is prepared by one or more processes including extrusion molding, casting molding, and machining; the connecting boss (22) and the forming mating section (21) of the mandrel (2) are an integral structure, the cross-sectional dimension of the connecting boss (22) is smaller than that of the forming mating section (21), and a mandrel (2) end face is formed at the root of the connecting boss (22) for connecting with the annular connecting sleeve (61) and transmitting circumferential forming load.

3. The method for drawing composite components based on precast blanks according to claim 1, characterized in that: The interface bonding structure (23) includes one or more combinations of toothed structure, pitted structure, raised structure and knurled structure; the toothed structure includes annular toothed groove or spiral toothed groove, the pitted structure and the raised structure are distributed along the axial and / or circumferential direction of the mandrel (2), and the knurled structure includes straight knurled, oblique knurled or mesh knurled structure.

4. The method for drawing composite components based on preformed blanks according to claim 1, characterized in that: The annular force transmission connection structure includes an annular connecting sleeve (61) and a pin (62); the annular connecting sleeve (61) is located at the end of the pressure rod (6) and forms a connecting cavity inside for the connecting boss (22) to be inserted; after assembly, the end of the annular connecting sleeve (61) near the mandrel (2) contacts the end face of the mandrel at the root of the connecting boss (22), and the axial forming load is transmitted to the mandrel (2) through this contact part; the pin (62) passes through the connecting hole (221) of the annular connecting sleeve (61) and the connecting boss (22) along an axial direction perpendicular to the mandrel (2) to maintain the detachable connection and limit the axial separation of the two.

5. The method for drawing composite components based on preformed blanks according to claim 1, characterized in that: The coaxial positioning state of the inlet is achieved by the matching and cooperation between the contour of the inlet of the drawing hole (41) and the outer periphery of the outer covering layer (1), which is used to limit the radial offset of the pre-made bimetallic blank (3) relative to the drawing hole (41) and ensure that the blank entry position corresponds coaxially with the forming hole.

6. The method for drawing composite components based on preformed blanks according to claim 1, characterized in that, The composite drawing forming zone includes the following configurations: A. Only one pull ring is set (4); B. Multiple drawing rings (4) are set along the forming direction (8), and the aperture of each drawing ring (4) decreases step by step; C. A number of drawing rings (4) arranged sequentially along the forming direction for preliminary diameter reduction and radial pre-compression of the blank, and a number of roller molds (5) located after the drawing rings (4) for continuously applying radial compression constraints to promote the complete filling of the outer coating layer (1) material and the combination of the coating interface.

7. The method for drawing composite components based on preformed blanks according to claim 1, characterized in that: After obtaining the bimetallic composite component (7), remove the pin (62) to separate the pressure rod (6) from the mandrel (2); completely cut off, partially cut off or completely retain the connecting boss (22). When partially cut off or completely retained, perform end forming, thread processing, connecting hole processing or assembly surface processing on the retained part to form an assembly connection structure, positioning structure or clamping structure.

8. A precast billet, characterized in that, The drawing forming method according to any one of claims 1-7 includes an outer cladding layer (1) made of a first metal material and a mandrel (2) made of a second metal material different from the first metal material; the outer cladding layer (1) is a shell structure with one end closed and the other end open and having a receiving cavity (13); the mandrel (2) includes a forming mating section (21) located in the receiving cavity (13) and a connecting boss (22) extending from the open end (14), the connecting boss (22) is provided with a connecting hole (221), and the outer peripheral surface of the forming mating section (21) is provided with an interface bonding structure (23); the end of the mandrel (2) located in the receiving cavity (13) contacts the inner side of the closed end (11) of the outer cladding layer (1) to form an axial force transmission relationship capable of transmitting axial forming load; the connecting boss (22) is used to insert an annular connecting sleeve (61) at the end of the pressure rod (6) and forms a detachable connection with the annular connecting sleeve (61) through a pin (62).

9. A composite component based on precast blanks, characterized in that, The drawing forming method according to any one of claims 1-7 includes a mandrel (2) and an outer covering layer (1) covering its outer periphery; the mandrel (2) has an interface bonding structure (23) on its outer periphery, and the material of the outer covering layer (1) completely fills the recessed part of the interface bonding structure (23) and completely covers its protruding part, and a mechanical interlocking interface (71) is formed between the two.

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