Hydraulic cold-drawing machine with built-in centering device

Abstract

The hydraulic cold-drawing machine with built-in centering device comprises a die seat provided with an outer die, a tail seat, a driving assembly arranged on the tail seat and configured to drive a straight movement of a core rod, a middle part of the core rod is composed of at least three main body sections, the diameters of the main body sections decrease step by step from the tail seat to the die seat, each main body section is slidably connected with a support block, when the core rod moves away from the outer die, the support block moves to the position of the main body section with the smallest diameter under the block of the tail seat, when the core rod moves to the outer die through the material pipe, the support block moves to the tail seat and abuts against the connecting step surface of the adjacent main body section in sequence, the support block is slidably arranged on the core rod, the abutting cooperation between the outer circumferential surface of the support block and the inner wall of the material pipe provides uniform radial support for the material pipe, the coaxial state of the material pipe and the core rod is forced, and the coaxiality of the material pipe and the drawing groove is indirectly ensured.

Description

Technical Field

[0001] This invention relates to the field of cold drawing machine technology, specifically a hydraulic cold drawing machine with a built-in centering device. Background Technology

[0002] Hydraulic cold drawing machines, as core equipment in the field of metal cold drawing, are widely used in the forming and processing of metal pipes such as seamless steel pipes due to their advantages of large drawing force, stable operation and high processing accuracy. They play an irreplaceable role, especially in the production of large-tonnage and large-size pipes.

[0003] The conventional workflow of the existing hydraulic cold drawing machine is as follows: the loading rack first pushes the tube to the drawing station, then the lifting cylinder is activated to lift the tube to a preset position coaxial with the mandrel. Next, the mandrel is inserted into the tube and moved to a state coaxial with the outer mold, so that the inner mold on the mandrel and the outer mold cooperate to form a circular drawing groove. Then, the pushing cylinder pushes the tube so that one end of the tube passes through the drawing groove. Finally, the drawing trolley is activated to grab the end of the tube, completing the drawing and forming operation of the tube.

[0004] In the above-mentioned drawing process, the coaxiality of the tube and the drawing groove is the core key factor that determines the smooth passage of the tube through the drawing groove, ensures the stability of the drawing and the quality of the finished product. The magnitude of the deviation directly affects the continuity of subsequent drawing operations.

[0005] Currently, existing hydraulic cold drawing machines generally suffer from insufficient coaxiality control precision. The main reason is the low driving precision of the lifting cylinder, which easily leads to height deviations in the material tube during lifting. Simultaneously, deviations in the horizontal installation position of the lifting cylinder itself further cause horizontal displacement of the material tube. The combined effect of these two deviations makes it difficult to effectively control the coaxiality of the material tube and the drawing groove, easily resulting in significant deviations.

[0006] This problem is particularly prominent in high-tonnage hydraulic cold drawing machines. For example, a 1600-ton cold drawing machine can process tubes weighing over 16 tons. The large weight of the tube amplifies the deviation caused by insufficient driving precision of the lifting cylinder, leading to a further increase in coaxiality deviation. This severely restricts the efficiency of the drawing operation and the quality of the finished product, and cannot meet the high-precision processing requirements of high-end tubes. Therefore, it is urgent to solve the technical problem of excessive coaxiality deviation between the tube and the drawing groove in existing hydraulic cold drawing machines. Summary of the Invention

[0007] To address the technical problems in the background art, the present invention discloses a hydraulic cold drawing machine with a built-in centering device.

[0008] This invention provides a hydraulic cold drawing machine with a built-in centering device, including a mold base with an outer mold, a tailstock, a drive assembly for driving a core rod to move linearly on the tailstock, and a pusher cylinder for driving a material tube to move towards the mold base; one end of the core rod is coaxially and fixedly connected to the inner mold, and the other end is fixedly connected to the drive end of the drive assembly; the middle part of the core rod is composed of at least three main body segments, and the diameter of each main body segment decreases in a stepped manner from the tailstock towards the mold base; Each main body segment is slidably connected to a support block; The outer circumferential surface of the support block abuts against the inner wall of the material tube, forming a coaxial positional relationship; When the core rod moves away from the outer mold, the support block moves to the position of the main body section with the smallest diameter under the obstruction of the tailstock; The connection of the main body section is inclined and transitioned; when the core rod moves through the material tube towards the outer mold, the support block moves towards the tailstock and abuts against the connecting step surface of the adjacent main body section in sequence; the support block closest to the tailstock abuts against the connecting step surface between the main body section and the tail end of the core rod last. As the support block moves toward the tailstock, it pushes the support block behind it onto the adjacent main body segment, and the support block that matches the size of the main body segment remains on the corresponding main body segment.

[0009] Furthermore, a linear bearing is inserted into the inner side of the support block, and the linear bearing is sleeved on the main body section and slidably connected to the main body section. The outer circumferential surface of the support block slides into the material tube.

[0010] Furthermore, the outer side of the support block is provided with a protrusion, which is in line contact with the material tube.

[0011] Furthermore, the inside of the convex strip is provided with an oil storage cavity for filling grease; An oil outlet hole connected to the oil storage cavity is also provided on the outer side of the convex strip; The grease in the oil storage chamber is driven by the pushing component to flow out from the oil outlet.

[0012] Furthermore, the grease in the oil storage chamber only flows out when the support block and the feed pipe slide relative to each other.

[0013] Furthermore, the oil storage cavity extends through both ends of the convex rib along its length. The pushing assembly includes push blocks inserted into both ends of the oil reservoir, and tension springs fixedly connected to the two push blocks at both ends respectively; The tension spring is set as follows: when the push blocks are located at both ends of the oil reservoir and the area between the two push blocks is filled with grease, the tension spring and the grease are in force balance, and the push blocks remain in their current positions.

[0014] Furthermore, a pull rod is connected to the outer end face of the push block. By pulling the pull rod, the push block can be pulled away from the oil storage chamber to fill with grease.

[0015] Furthermore, along the length extension direction of the convex strip, there are multiple oil outlet holes, and the multiple oil outlet holes are arranged at intervals; When the tension spring is contracted to its shortest length, all oil outlets are located between the two push blocks.

[0016] Furthermore, a tube expansion cylinder is also installed on the tailstock. The drive end of the tube expansion cylinder is connected to the tube expansion head through a tension chain, and can drive the tube expansion head to rise and fall. The tail end of the core rod, in the area outside the tailstock, is provided with a washer and a lock nut at intervals, and a groove is formed between the washer and the lock nut; The washer is fixed to the tailstock; The expansion head is an arc shape with an opening facing downwards. By raising and lowering the expansion head, the expansion head can be moved away from or locked into the slot.

[0017] Furthermore, multiple lifting cylinders are provided on the lower side between the mold base and the tailstock. The lifting cylinders are used to drive the material tube to rise, so as to overcome the bending deformation of the core rod and the material tube caused by one end being suspended. Multiple limiting wheels are provided on the upper side between the mold base and the tailstock. The limiting wheels are used to limit the upward movement of the material tube.

[0018] The beneficial effects of this invention are: 1. This invention provides uniform radial support to the material tube by sliding a support block on the core rod and utilizing the abutment between the outer circumferential surface of the support block and the inner wall of the material tube. This forces the material tube and the core rod to maintain a coaxial state, thereby indirectly ensuring the coaxiality of the material tube and the drawing groove. This fundamentally solves the problem of coaxiality deviation caused by insufficient driving accuracy of the lifting cylinder and horizontal installation deviation in the prior art.

[0019] 2. The stepped main body design, combined with the sliding and retaining mechanism of the support block, enables the device to automatically adapt to the transition of the core rod in different diameter sections. The support block automatically matches and maintains effective support for the material tube according to the diameter of the main body section, enhancing the equipment's adaptability to material tubes of different specifications.

[0020] 3. Through the step surface contact and sequential pushing mechanism of the support block, the support block is reliably reset and redistributed during the reciprocating movement of the core rod, avoiding support interference or detachment, ensuring the smooth progress of the drawing operation, and improving production efficiency.

[0021] 4. The device is integrated into the mandrel, eliminating the need for additional complex drive or adjustment mechanisms. The centering function can be achieved using the existing mandrel movement. It has a compact structure, reliable operation, and is easy to modify or upgrade on existing hydraulic cold drawing machines. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a structural schematic diagram of the hidden part of the present invention, wherein the expansion tube pressure head is engaged in the slot; Figure 3 This is a structural schematic diagram of the hidden part of the present invention, wherein the expansion tube pressure head is in a rising position away from the slot; Figure 4 This is a structural schematic diagram of the hidden parts of the present invention, mainly showing the installation structure of the limiting wheel and the support wheel; Figure 5 This is a schematic diagram of the installation structure of the core rod and its support block, in which the core rod is in a state of extending towards the mold base; Figure 6 It is relative to Figure 5 Front sectional view; Figure 7 yes Figure 6 Enlarged view of point A in the middle; Figure 8 This is the front view of the core rod; Figure 9 This is a structural schematic diagram of the support block; Figure 10 This is a schematic diagram of the installation structure of the core rod and its support block, in which the core rod is in a retracted state away from the mold base; In the diagram: 1. Outer mold; 2. Mold base; 3. Tailstock; 4. Core rod; 5. Material tube; 6. Pushing cylinder; 7. Inner mold; 8. Support block; 9. Linear bearing; 10. Push block; 11. Tension spring; 12. Tie rod; 13. Expanding cylinder; 14. Tension chain; 15. Expanding head; 16. Washer; 17. Locking nut; 18. Slot; 19. Lifting cylinder; 20. Limiting wheel; 21. Support wheel; 22. Guide wheel; 23. Cylinder base; 24. Support rod; 25. Track frame; 26. Guide rail; 27. Slide; 41. Main body section; 81. Protrusion; 82. Oil storage chamber; 83. Oil outlet. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0025] like Figure 1As shown, this invention discloses a hydraulic cold drawing machine with a built-in centering device, comprising a tailstock 3, a die holder 2, and a cylinder seat 23 arranged sequentially at intervals along the drawing direction of the material tube 5. The tailstock 3 and the die holder 2 are connected as a whole by four symmetrically arranged support rods 24 forming a square, and the die holder 2 and the cylinder seat 23 are also connected as a whole by four symmetrically arranged support rods 24 forming a square. A track frame 25 is provided on the outer side of the tailstock 3, and two symmetrically arranged guide rails 26 are provided on the track frame 25. A slide 27 is slidably connected to the guide rails 26 and moves linearly. The slide 27 is driven by a drive assembly on the track frame 25 to achieve linear reciprocating movement. The specific structure of the drive assembly is as follows: a drive sprocket and a driven sprocket are respectively provided at both ends of the track frame 25, and the drive sprocket and the driven sprocket are linked by a meshing driven chain. The drive sprocket is a double sprocket, one of which meshes with the driven chain, and the other sprocket is linked with the drive sprocket through the drive chain; the drive sprocket is installed at the drive end of the drive motor.

[0026] like Figure 2 and Figure 3 As shown, the core rod 4 passes through the tailstock 3, and its tail end is fixedly mounted on the slide block 27 by a locking nut 17. A washer 16, which is fixedly connected to the tailstock 3, is also sleeved on the core rod 4. The washer 16 is an arc shape with an opening facing downwards, and its inner wall is coaxial with the core rod 4 with a clearance fit. Since the material tube 5 must be sleeved on the inner mold 7 before being pulled out, and the core rod 4 cannot move axially during the process of sleeved on the inner mold 7, a tube expansion cylinder 13 is also installed on the tailstock 3. The driving end of the cylinder is equipped with a tube expansion head 15 to drive the tube expansion head 15 to rise and fall. The tube expansion head 15 is an arc shape with an opening facing downwards. When it descends and clamps the core rod 4 by adhering to the core rod 4 with its inner wall, the tube expansion head 15 is clamped in the groove 18 formed between the washer 16 and the locking nut 17, and the two axial ends of the tube expansion head 15 abut against the washer 16 and the locking nut 17 respectively to achieve axial limitation of the core rod 4.

[0027] The expansion head 15 is generally rigidly connected to the expansion cylinder 13. When impacted by the locking nut 17, it is prone to damage. Therefore, the following design is implemented: a horizontally extending mounting base is installed on the top of the tailstock 3, and the expansion cylinder 13 is horizontally fixed on the mounting base. A guide wheel 22 is also provided on the mounting base. The tension chain 14 passes over the guide wheel 22 from above, with one end fixedly connected to the drive end of the expansion cylinder 13; the other end of the tension chain 14 extends downwards and is fixedly connected to the expansion head 15. The expansion head 15 is connected to the drive end of the expansion cylinder 13 via the tension chain 14, forming a flexible transmission. When the core rod 4 vibrates or rebounds due to force during the pulling process, causing the locking nut 17 at its tail end to impact the expansion head 15, the tension chain 14 can effectively absorb and buffer the impact energy, preventing the impact force from being directly and rigidly transmitted to the expansion cylinder 13. This significantly reduces the risk of damage to the expansion cylinder 13 and its connecting parts due to direct impact, and improves the reliability and service life of key components of the equipment.

[0028] Two symmetrically arranged pusher cylinders 6 are also installed on the tailstock 3, with their drive ends facing the material tube 5. The drive ends of the pusher cylinders 6 are connected as a whole by a connecting plate. When the pusher cylinders 6 extend, they drive the material tube 5 to move towards the drawing groove and pass through the drawing groove. To improve the movement stability of the connecting plate, a roller is provided at the lower end of the connecting plate. A guide plate is provided between the tailstock 3 and the mold base 2, which is slidably connected to the roller and supports and engages the roller.

[0029] like Figure 8 As shown, the core rod 4 is composed of at least three main body segments 41 in the middle, and the diameter of each main body segment 41 decreases in a stepped manner from the tailstock 3 towards the mold base 2. In this embodiment, the main body segments 41 are provided with three segments, and the connection of the main body segments 41 is transitioned by a slope structure. Each main body segment 41 is slidably connected to a support block 8, and the outer peripheral surface of the support block 8 abuts against the inner wall of the material tube 5 to provide radial support, so that the material tube 5 and the core rod 4 are coaxial.

[0030] The specific structure of the support block 8 is as follows: an axial through mounting hole is provided at the center of the support block 8, and a linear bearing 9 is inserted into the mounting hole by interference fit. The linear bearing 9 is set to three types that match the main body section 41, and each type of linear bearing 9 is slidably connected to the matching main body section 41.

[0031] like Figure 9 As shown, the outer side of the support block 8 is provided with multiple circumferentially evenly spaced protrusions 81 extending along the axial direction of the support block 8. The cross-section of the protrusions 81 is arc-shaped, so that the protrusions 81 and the material tube 5 are in line contact and sliding connection. This arrangement maintains sufficient friction between the protrusions 81 and the material tube 5, and the small contact area allows the support block 8 and the material tube 5 to slide stably relative to each other.

[0032] like Figure 10 As shown, when the core rod 4 moves away from the outer mold 1, the support block 8 moves to the position of the main body section 41 with the smallest diameter under the obstruction of the tailstock 3. Figure 5 As shown, when the core rod 4 moves through the material tube 5 towards the outer mold 1, the support block 8 moves towards the tailstock 3 and successively abuts against the connecting step surface of the adjacent main body section 41; the support block 8 closest to the tailstock 3 is the last to abut against the connecting step surface between the main body section 41 and the tail end of the core rod 4. Figure 10 As shown, during the movement of the support block 8 toward the tailstock 3, the support block 8 behind this support block 8 will be pushed onto the adjacent main body section 41, and the support block 8 that matches the size of the main body section 41 will remain on the corresponding main body section 41.

[0033] Among them, such as Figure 6 and Figure 7 As shown, the protruding strip 81 has an oil storage cavity 82 for filling grease, and the oil storage cavity 82 is a through hole passing through both ends of the protruding strip 81 axially. The outer side of the protruding strip 81 also has an oil outlet hole 83 that communicates with the oil storage cavity 82 and extends radially. The grease in the oil storage cavity 82 is driven by the pushing assembly to flow out from the oil outlet hole 83.

[0034] To prevent grease from flowing out of the oil outlet 83 when the core rod 4 is not in operation, and to ensure that the grease only flows out when the support block 8 and the feed tube 5 slide relative to each other, the pushing assembly is configured to include push blocks 10 inserted into both ends of the oil storage cavity 82, and tension springs 11 fixedly connected to the two push blocks 10 at both ends. The tension springs 11 are configured such that when the push blocks 10 are located at both ends of the oil storage cavity 82, and the area of ​​the oil storage cavity 82 between the two push blocks 10 is filled with grease, the force of the tension springs 11 and the grease reaches force balance, and the push blocks 10 remain in their current positions. In this embodiment, after the oil outlet 83 is filled with grease, a plastic film is used to seal it, thereby keeping the tension springs 11 stationary. With this setup, the plastic film is removed before the core rod 4 is inserted into the tube 5. When the support block 8 slides relative to the tube 5, grease is applied to the inner wall of the tube 5. When the grease in the oil outlet 83 decreases, the grease is forced into the oil outlet 83 by the tension spring 11 and the push block 10, achieving automatic and continuous application. This effectively reduces the frictional resistance between the support block 8 and the inner wall of the tube 5, reducing energy consumption during the drawing process and avoiding surface scratches or jamming caused by dry friction. Simultaneously, the reduced friction during the cold drawing process of the tube 5 results in more uniform force distribution and smoother flow, effectively preventing problems such as uneven wall thickness and excessive ovality caused by uneven resistance, thus ensuring more precise finished product dimensions.

[0035] When the tension spring 11 is contracted to its shortest length, all oil outlet holes 83 are located between the two push blocks 10. This ensures that all oil outlet holes 83 are always in contact with grease and perform lubrication throughout the entire lubrication cycle. This avoids the problem of some oil outlet holes 83 being exposed in the cavity and unable to supply oil due to the push block 10 moving beyond the range of the oil outlet holes 83, thus preventing grease waste and local lubrication failure.

[0036] To facilitate the filling of grease into the oil storage chamber 82, a pull rod 12 is connected to the outer end face of the push block 10. By pulling the pull rod 12, the push block 10 can be pulled away from the oil storage chamber 82 for filling with grease.

[0037] Because the material tube 5 and the core rod 4 are relatively heavy and have a large deflection, the end with the inner mold 7 is prone to sag. Therefore, if Figure 4 As shown, multiple lifting cylinders 19 are provided on the lower side between the mold base 2 and the tailstock 3. The driving end of the lifting cylinder 19 is provided with a support wheel 21, which is used to drive the material tube 5 to rise, so as to overcome the bending deformation of the core rod 4 and the material tube 5 due to one end being suspended. Multiple limiting wheels 20 are provided on the upper side between the mold base 2 and the tailstock 3. The limiting wheels 20 are used to limit the rising range of the material tube 5.

[0038] Compared with existing technologies, the advantages of this embodiment are: 1. By sliding the support block 8 on the core rod 4, the present invention utilizes the abutment between the outer circumferential surface of the support block 8 and the inner wall of the material tube 5 to provide uniform radial support for the material tube 5, forcing the material tube 5 and the core rod 4 to maintain a coaxial state, thereby indirectly ensuring the coaxiality of the material tube 5 and the drawing groove, fundamentally solving the coaxiality deviation problem caused by insufficient driving accuracy of the lifting cylinder 19 and horizontal installation deviation in the existing technology. 2. The stepped main body section 41 design, combined with the sliding and retaining mechanism of the support block 8, enables the device to automatically adapt to the transition of the core rod 4 in different diameter sections. The support block 8 automatically matches and maintains effective support for the material tube 5 according to the diameter of the main body section 41 it is in, enhancing the equipment's adaptability to material tubes of different specifications. 3. Through the stepped surface abutment and sequential pushing mechanism of the support block 8, reliable reset and redistribution of the support block 8 are achieved during the reciprocating movement of the core rod 4, avoiding support interference or detachment, ensuring smooth drawing operations, and improving production efficiency. 4. The device is integrated into the core rod 4, eliminating the need for additional complex drive or adjustment mechanisms. The centering function can be achieved by utilizing the existing movement of the core rod 4. It has a compact structure, reliable operation, and is easy to modify or upgrade on existing hydraulic cold drawing machines.

[0039] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A hydraulic cold drawing machine with a built-in centering device, comprising a mold base (2) with an outer mold (1), and a tailstock (3), wherein a drive assembly for driving a core rod (4) to move linearly is provided on the tailstock (3), and a pusher cylinder (6) for driving a material tube (5) to move toward the mold base (2); one end of the core rod (4) is coaxially and fixedly connected to an inner mold (7), and the other end is fixedly connected to the drive end of the drive assembly; characterized in that: The core rod (4) is composed of at least three main body segments (41) in the middle, and the diameter of each main body segment (41) decreases in a stepwise manner from the tailstock (3) to the mold base (2). Each of the main body segments (41) is slidably connected to a support block (8); The outer peripheral surface of the support block (8) abuts against the inner wall of the material pipe (5) to form a coaxial positional relationship; When the core rod (4) moves away from the outer mold (1), the support block (8) moves to the position of the main body section (41) with the smallest diameter under the obstruction of the tailstock (3); The connection of the main body section (41) is inclined and transitioned; when the core rod (4) moves through the material tube (5) towards the outer mold (1), the support block (8) moves towards the tailstock (3) and abuts against the connecting step surface of the adjacent main body section (41) in sequence; the support block (8) closest to the tailstock (3) abuts against the connecting step surface of the main body section (41) and the tail end of the core rod (4) last. During the process of the support block (8) moving towards the tailstock (3), the support block (8) behind the support block (8) will be pushed into the adjacent main body section (41), and the support block (8) matching the size of the main body section (41) will remain on the corresponding main body section (41). A linear bearing (9) is inserted into the inner side of the support block (8), and the linear bearing (9) is sleeved on the main body section (41) and slidably connected to the main body section (41). The outer peripheral surface of the support block (8) is in sliding fit with the material tube (5); The outer side of the support block (8) is provided with a protrusion (81), and the protrusion (81) is in line contact with the material tube (5); The protrusion (81) has an oil storage cavity (82) for filling grease inside; The outer side of the protrusion (81) is also provided with an oil outlet (83) that communicates with the oil storage cavity (82). The grease in the oil storage chamber (82) is driven by the pushing component to flow out from the oil outlet (83).

2. A hydraulic cold drawing machine with a built-in centering device according to claim 1, characterized in that: The grease in the oil storage chamber (82) flows out only when the support block (8) and the feed pipe (5) slide relative to each other.

3. A hydraulic cold drawing machine with a built-in centering device according to claim 2, characterized in that: The oil storage cavity (82) extends through both ends of the protrusion (81) along the length direction of the protrusion (81); The pushing assembly includes push blocks (10) inserted into both ends of the oil reservoir (82), and tension springs (11) fixedly connected to the two push blocks (10) at both ends respectively. The elastic force of the tension spring (11) is set as follows: when the push block (10) is located at both ends of the oil storage chamber (82) and the area between the two push blocks (10) of the oil storage chamber (82) is filled with grease, the force of the tension spring (11) and the grease reaches force balance, and the push block (10) remains unchanged in its current position.

4. A hydraulic cold drawing machine with a built-in centering device according to claim 3, characterized in that: The outer end face of the push block (10) is connected to a pull rod (12). By pulling the pull rod (12), the push block (10) can be pulled away from the oil storage chamber (82) to fill with grease.

5. A hydraulic cold drawing machine with a built-in centering device according to claim 3, characterized in that: Along the length extension direction of the protrusion (81), there are multiple oil outlet holes (83), and the multiple oil outlet holes (83) are arranged at intervals; When the tension spring (11) is contracted to its shortest length, all oil outlets (83) are located between the two push blocks (10).

6. A hydraulic cold drawing machine with a built-in centering device according to claim 1, characterized in that: The tailstock (3) is also equipped with a tube expansion cylinder (13). The drive end of the tube expansion cylinder (13) is connected to the tube expansion head (15) through a tension chain (14) and can drive the tube expansion head (15) to rise and fall. The tail end of the core rod (4) is provided with a washer (16) and a locking nut (17) at intervals in the area outside the tail seat (3), and a groove (18) is formed between the washer (16) and the locking nut (17). The washer (16) is fixed to the tailstock (3); The expansion head (15) is an arc shape with an opening facing downwards. By raising and lowering the expansion head (15), the expansion head (15) can be moved away from or locked into the slot (18).

7. A hydraulic cold drawing machine with a built-in centering device according to claim 1, characterized in that: Multiple lifting cylinders (19) are provided on the lower side between the mold base (2) and the tailstock (3). The lifting cylinders (19) are used to drive the material tube (5) to rise, so as to overcome the bending deformation caused by the core rod (4) and the material tube (5) being suspended at one end. Multiple limiting wheels (20) are provided on the upper side between the mold base (2) and the tailstock (3). The limiting wheels (20) are used to limit the upward range of the material tube (5).

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