Core rod trolley for precise forging of special thick-walled pipe

Abstract

The core rod trolley for precise forging of the special thick-walled pipe comprises a frame assembly, a sliding assembly in sliding fit with a sliding rail is arranged at the bottom of the frame assembly, and a driving system connected with the sliding assembly is arranged in the sliding rail; two groups of driving oil cylinders are symmetrically arranged on the sliding rail; a clamping device for clamping and locking a piston rod of the driving oil cylinder is arranged at the rear end of the frame assembly; a core rod supporting flange and a cooling water flow channel are arranged in the frame assembly, and a water pipe connector at the tail of the frame assembly is communicated with a cooling cavity in a core rod through the cooling water flow channel. The problems that an existing core rod trolley is short in stroke, low in cooling efficiency and poor in clamping stability are solved, long-stroke integrated precision forging of the special thick-wall pipe is achieved, the service life and the size stability of a core rod are guaranteed through efficient inner cooling, and the feeding precision and safety in the forging process are guaranteed through a reliable clamping structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal pipe plastic forming equipment, in particular to a core rod trolley for precision forging of special thick-walled pipes. BACKGROUND

[0002] In the field of thick-walled pipe manufacturing, the forming process directly determines the organizational structure and mechanical properties of the product. As a representative of precision forming process, radial forging forming makes the metal blank continuously plastically deform under dynamic pressure through the synchronous high-frequency beating of multiple hammer heads along the radial direction of the blank, which can effectively refine the grain and optimize the material performance. It has become the preferred process for key high-pressure thick-walled components in the military high-strength pipe fittings and petrochemical, nuclear power and other industries.

[0003] In the radial forging process, the main machine hammer head performs radial forging on the hollow pipe fitting, the clamp holds the pipe fitting and rotates and feeds axially, and the core rod needs to be accurately fed into the pipe fitting and stably positioned at the forging position. The core rod trolley is the main power and support device for providing core rod feeding, withdrawing and cooling. The performance of the core rod trolley directly determines the feasibility, stability of the forging process and the quality of the final product.

[0004] Currently, the general core rod trolley suitable for ordinary thin-walled pipes or short-size pipe fittings has exposed a series of technical defects in the forging scene of special thick-walled pipes. First, due to the limitation of the driving stroke of the hydraulic cylinder, the existing device cannot meet the integrated forging demand of special thick-walled pipes with a length of more than 8 meters, forcing enterprises to adopt the process of segmented forging and welding, which leads to the decrease of the strength of the welded joint and introduces the risk of corrosion and leakage. Second, the commonly used external spray cooling method can only cool the outer surface of the core rod, resulting in excessive internal temperature of the core rod, which causes thermal fatigue softening, hardness decrease and thermal stress cracks, not only shortening the service life of the core rod, but also scratching the inner wall of the pipe fitting due to crack propagation. Third, the common plug-in plate type clamping structure has small contact area, which is easy to cause stress concentration, plastic deformation or even fracture, and has poor clamping stability.

[0005] Therefore, it is of great significance to develop a special core rod trolley with ultra-long stroke, high-efficiency internal cooling and reliable clamping capacity for fully exerting the advantages of radial forging process and ensuring the high-quality production of special thick-walled pipes. SUMMARY

[0006] The purpose of the present application is to provide a core rod trolley for precision forging of special thick-walled pipes, to solve the problems of short stroke, low cooling efficiency and poor clamping stability of the existing core rod trolley, and to realize integrated, high-precision and stable forging of long-size special thick-walled pipes.

[0007] In order to achieve the above object, the present application provides the following technical scheme: a mandrel trolley for precision forging of special thick-walled pipes, comprising a trolley assembly, a sliding assembly is arranged at the bottom of the trolley assembly, and the sliding assembly is in sliding cooperation with a sliding rail; a driving system is arranged inside the sliding rail, the driving system is connected with the sliding assembly to drive the trolley assembly to quickly feed and retreat along the sliding rail; two groups of driving oil cylinders are symmetrically arranged on the sliding rail, and the cylinder barrels of the driving oil cylinders are fixedly installed on the sliding rail; the rear end of the trolley assembly is provided with two groups of clamping devices for clamping and locking the piston rods of the driving oil cylinders and the trolley assembly; a mandrel support flange is arranged inside the trolley assembly, the mandrel support flange supports a mandrel assembly and keeps concentric with a forging center of a radial forging machine; A water pipe joint is arranged at the tail of the trolley assembly, and a cooling water flow channel is integrated inside the trolley assembly, the cooling water flow channel communicates the water pipe joint with a cooling cavity inside the mandrel assembly.

[0008] Preferably, the driving system comprises a hydraulic motor and a chain wheel transmission structure, the chain wheel transmission structure comprises a driving chain wheel and a driven chain wheel, the output end of the hydraulic motor is in transmission connection with the driving chain wheel, the driving chain wheel and the driven chain wheel are in transmission cooperation through a chain, and the chain is connected with the sliding assembly at the bottom of the trolley assembly.

[0009] Preferably, the driving chain wheel is sleeved on a driving chain wheel shaft and is in interference fit, one end of the driving chain wheel shaft is connected with the output shaft of the hydraulic motor through a flat key, the other end is assembled and connected with the sliding rail through a spherical roller thrust bearing and a bearing end cover; and the driven chain wheel is installed on a driven chain wheel shaft through two groups of single-row roller bearings.

[0010] Preferably, the driven chain wheel shaft is installed in a chain wheel tensioning device, the chain wheel tensioning device comprises an adjusting support, a support plate, an adjusting screw and a nut, the support plate is welded and fixed on the sliding rail, one end of the adjusting screw is provided with the nut, and the other end penetrates into the adjusting support; the adjusting screw is moved by rotating the nut to pull the adjusting support to tighten the chain.

[0011] Preferably, the clamping device adopts a scissors arm structure, comprising a first clamping arm, a second clamping arm, a pin shaft, a clamping oil cylinder and a jaw, the first clamping arm and the second clamping arm are hinged with the trolley assembly through the pin shaft, the cylinder barrel end of the clamping oil cylinder is hinged with the second clamping arm, the piston rod end is hinged with the first clamping arm, and the jaw is installed at the end of the first clamping arm and the second clamping arm.

[0012] Preferably, the mandrel support flange is connected with a first mandrel connecting pipe through a flange sleeve, the first mandrel connecting pipe is connected with a mandrel outer pipe through a second mandrel connecting pipe; the cooling water flow channel comprises a water inlet pipe joint and a water return pipe joint, the water inlet pipe joint is communicated with a mandrel inner pipe through a first cooling pipe and a second cooling pipe in sequence, and an annular backflow cavity is formed between the mandrel inner pipe and the mandrel outer pipe.

[0013] Preferably, the inner tube of the mandrel is provided with a plurality of water flow channels arranged axially, and a sealing plug is welded at one end of the outer tube of the mandrel, and the inside of the sealing plug is connected with the inner tube through threads.

[0014] Preferably, stud type bumpers are symmetrically arranged and fixedly installed at both sides of the rear end of the frame assembly, and the stud type bumpers are provided with rubber bumping heads and bumping springs.

[0015] Preferably, the frame assembly is formed by welding using Q355B low-alloy high-strength steel, and the driving oil cylinder is provided with a hydraulic valve group, which is an electro-hydraulic proportional valve group.

[0016] Preferably, the outer surface of the outer tube of the mandrel assembly is designed with a micro taper; the driving system is provided with an encoder for detecting the position of the frame assembly; and proximity switches are arranged beside the first clamping arm and the second clamping arm of the clamping device for monitoring the clamping and loosening actions.

[0017] The working process of the present application is as follows: The position of the main machine hammer head is adjusted according to the pipe specification, the chuck clamps one end of the pipe and starts to rotate. The hydraulic motor of the mandrel trolley drives the frame assembly to quickly advance along the slide rail until the front end of the mandrel assembly is aligned with the inner hole entrance of the thick-walled pipe. After the mandrel trolley reaches the preset position, the clamping device acts, the piston rod of the jaw clamping driving oil cylinder is clamped, and locking is realized. Then, the driving oil cylinder slowly pushes the mandrel trolley and the mandrel assembly into the pipe hole under the control of the electro-hydraulic proportional valve group, and the internal water cooling system starts. During the forging process, the chuck drives the pipe to move axially, and the mandrel continuously and slowly feeds under the precise control of the driving oil cylinder, completing continuous forging. When the chuck moves to the front limit position, the forging stops. At this time, the clamping oil cylinder is depressurized, the jaw is opened, and the driving oil cylinder is disconnected with the mandrel trolley. The hydraulic motor is started in reverse to drive the mandrel trolley and the mandrel assembly to quickly retreat to the initial position, waiting for the next working cycle. During the whole process, the position of the mandrel trolley is detected at any time by the encoder and fed back to the PLC control system, realizing accurate position control.

[0018] The present application has the following advantages: (1) The present application realizes the fast and long-stroke feeding capability of the mandrel trolley over 9 meters by adopting the cooperation of the chain wheel transmission system driven by the hydraulic motor and the long-stroke slide rail. This design fundamentally solves the technical bottleneck of insufficient driving stroke of the existing hydraulic cylinder, enables the special thick-walled pipe over 8 meters to realize integrated continuous forging, avoids the joint strength reduction, intergranular corrosion and leakage risk caused by the traditional segmented forging and welding process, and significantly improves the overall mechanical properties and service safety of the pipe.

[0019] (2) The integrated internal circulation water cooling system is innovatively adopted. Cooling water directly enters the cooling cavity in the core rod through the flow channel in the frame, and circularly flows back, so that the working temperature of the core rod can be stably controlled below 150 DEG C. Compared with the traditional external spray cooling mode, the internal cooling structure greatly improves the cooling efficiency and uniformity, effectively avoids the thermal fatigue softening, hardness reduction of the core rod due to high temperature (350-500 DEG C) and the thermal stress cracks due to the large temperature difference between the inside and outside, thereby greatly prolonging the service life of the core rod, and ensuring the surface quality and size precision of the inner hole of the forging, reducing the subsequent machining allowance and material loss.

[0020] (3) The shearing arm type clamping device driven by hydraulic pressure is adopted to replace the traditional plug-in plate type structure, so that the reliability and shearing resistance of clamping are significantly improved. The clamping device drives the first and second clamping arms to rotate around the pin shaft through the clamping oil cylinder, so that the jaw can tightly and uniformly hold the driving oil cylinder piston rod, the contact area is large, and local stress concentration is avoided. Combined with the precise control of the electro-hydraulic proportional valve group on the feeding speed of the driving oil cylinder, the stability and wall thickness uniformity of the core rod slow feeding in the forging process are ensured, and the quick switching of clamping and loosening is realized through hydraulic automatic control, so that the operation efficiency and the automation level of the equipment are improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is the overall layout schematic diagram of the core rod trolley in the forging machine set. Figure 2 It is the external schematic diagram of the driving system. Figure 3 It is the driving system along the A-A line. Figure 2 Figure 4 It is the driving system along the B-B line. Figure 2 Figure 5 It is the driving system along the C-C line. Figure 2 Figure 6 It is the schematic diagram of the sliding assembly. Figure 7 It is the schematic diagram of the clamping device. Figure 8 It is the longitudinal sectional view of the core rod trolley. ​​​In the diagram: 1-Mandrel carriage, 2-Slide rail, 3-Connecting pipe, 4-Drive cylinder, 5-Chuck, 6-Thick-walled pipe fitting, 7-Mandrel assembly, 8-Forging main unit, 9-Clamping device, 11-Hydraulic motor, 12-Chain, 13-Frame assembly, 14-Driven sprocket, 15-Encoder, 16-Bolt, 17-Drive sprocket shaft, 18-Drive sprocket, 19-Spherical roller thrust bearing, 20-Bearing end cover, 21-Support plate, 22-Driven sprocket shaft, 23-Single row roller bearing, 24-Adjusting bracket, 25-Bolt assembly, 26-Adjusting screw. 27-Nut, 28-Sliding assembly, 30-Clamping cylinder, 31-Pin, 32-First clamping arm, 33-Jaws, 34-Proximity switch, 35-Second clamping arm, 40-Mandrel support flange, 41-Flange sleeve, 42-Firming plate, 43-First mandrel connecting pipe, 44-First cooling pipe, 45-Bearing, 46-Bearing seat, 47-Second cooling pipe, 48-Second mandrel connecting pipe, 49-Mandrel outer tube, 50-Mandrel inner tube, 51-Sealing plug, 52-Return water pipe connector, 53-Inlet water pipe connector, 54-Stud-type buffer. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings.

[0023] like Figure 1 As shown, the mandrel carriage 1 in this invention is installed behind the chuck 5, and the central axis of the mandrel carriage 1 coincides with the clamping central axis of the chuck 5. The functions of the mandrel carriage 1 are: to support and drive the mandrel assembly 7 to quickly approach the workpiece, to provide slow and precise feeding during forging, to provide efficient cooling, and to quickly return to the initial position after forging. The frame assembly 13 of the mandrel carriage 1 is mounted on the slide rail 2 via the sliding assembly 28 at its bottom, and the slide rail 2 provides linear guidance for the movement of the frame assembly 13. The slide rail 2 is fixedly connected to the mounting base of the drive cylinder 4 to ensure that the mandrel carriage 1 can accurately dock with the drive cylinder 4 after it is in position. During forging, the chuck 5 clamps the thick-walled tube 6, rotates and moves axially, and the mandrel assembly 7, driven by the mandrel carriage 1, precisely extends into the inner hole of the thick-walled tube 6 along a coaxial path to ensure that the inner hole of the forging is not eccentric.

[0024] See Figures 2 to 5The driving system is integrated in the cavity formed by the bottom of the mandrel trolley 1 and the slide rail 2, and is used for fast advancing of the mandrel trolley 1 before forging. The hydraulic motor 11 is fastened and installed on the side of the slide rail 2 through the bolt 16. The output shaft of the hydraulic motor 11 realizes torque transmission through the flat key and the driving sprocket shaft 17. The driving sprocket shaft 17 is the main transmission shaft, one end of which is connected with the hydraulic motor 11, and the other end is supported on the slide rail 2 through the spherical roller thrust bearing 19 and the bearing end cover 20. The driving sprocket 18 is sleeved on the middle part of the driving sprocket shaft 17, adopts interference fit, and is bidirectionally axially limited through the shaft shoulder and the retainer, so as to ensure synchronous rotation with the driving sprocket shaft 17. The driven sprocket 14 is arranged at the end of the driving system away from the hydraulic motor 11. The driven sprocket 14 is installed on the driven sprocket shaft 22 through two groups of single-row roller bearings 23. The driven sprocket shaft 22 is assembled in a sprocket tensioning device composed of an adjusting bracket 24, a support plate 21, an adjusting screw 26 and a nut 27. The support plate 21 is welded and fixed on the slide rail 2, the adjusting screw 26 is threaded at both ends, one end is assembled with the nut 27, and the other end penetrates the adjusting bracket 24. By rotating the nut 27 with a wrench, the adjusting screw 26 can be pushed to move, thereby driving the adjusting bracket 24 to displace, so as to manually adjust the tensioning force of the chain 12 to compensate for the relaxation after chain wear or stretching. After adjustment, the adjusting bracket 24 is fixed on the slide rail 2 by using the bolt set 25. The chain 12 is sleeved on the teeth of the driving sprocket 18 and the driven sprocket 14 to form a closed transmission chain. The bottom of the frame assembly 13 is provided with a mounting groove, and the sliding assembly 28 is fixed in the groove through bolts. The lower part of the sliding assembly 28 is provided with a circular hole, and the pin shaft of the chain 12 is rigidly connected with the chain 12. When the hydraulic motor 11 is started, the torque is transmitted to the driving sprocket 18 through the driving sprocket shaft 17, the chain 12 is driven to move, and then the driven sprocket 14 is synchronously rotated. The linear motion of the chain 12 is converted into the linear motion of the frame assembly 13 along the slide rail 2 through the sliding assembly 28, so as to realize smooth and fast feeding and retreating of the mandrel trolley 1 with a maximum design stroke of 9 meters.

[0025] When the driving system sends the mandrel trolley 1 to the preset forging starting position, the power source needs to be switched. Figure 1 and Figure 7As shown, at this time, the clamping device 9 installed at the rear end of the frame assembly 13 starts to act. The clamping device 9 adopts a scissors arm structure driven by hydraulic pressure, including a clamping oil cylinder 30, a first clamping arm 32, a second clamping arm 35, a pin shaft 31 and a jaw 33. The cylinder end of the clamping oil cylinder 30 is hinged with the second clamping arm 35, and the piston rod end is hinged with the first clamping arm 32. The first clamping arm 32 and the second clamping arm 35 are hinged with the frame assembly 13 through the pin shaft 31. The execution end of the first clamping arm 32 and the second clamping arm 35 is provided with the jaw 33, and the working surface of the jaw 33 is designed according to the contour of the piston rod of the driving oil cylinder 4, to ensure close fit. When the clamping oil cylinder 30 extends, the first clamping arm 32 and the second clamping arm 35 are pushed to rotate relative to the pin shaft 31, so that the jaw 33 is closed to tightly hold the piston rod of the driving oil cylinder 4, and the rigid locking of the driving oil cylinder 4 and the frame assembly 13 is realized. After locking, the hydraulic motor 11 of the driving system stops oil supply, and the feeding power of the mandrel trolley 1 is completely provided by the driving oil cylinder 4. The driving oil cylinder 4 is provided with an electro-hydraulic proportional valve group, which can precisely and steplessly adjust the feeding speed of the oil cylinder, so as to realize the accurate action of the mandrel in the forging process and ensure the uniformity of the wall thickness of the special thick-walled pipe. A proximity switch 34 is also arranged beside the first clamping arm 32 and the second clamping arm 35, which is used to monitor the position of the clamping arm in real time, so as to feedback the clamping and loosening state of the clamping device.

[0026] As shown in the figure, Figure 8 The rear end of the frame assembly 13 is provided with a mandrel support flange 40 through bolt fastening. The mandrel support flange 40 is connected with a flange sleeve 41 through circumferential bolts, the flange sleeve 41 is connected with a first mandrel connecting pipe 43 through threads, the first mandrel connecting pipe 43 is connected with a second mandrel connecting pipe 48 through flanges, and the second mandrel connecting pipe 48 is connected with a mandrel outer pipe 49 through threads, thereby forming a stable support system for the mandrel assembly 7 and ensuring that the axis of the mandrel assembly 7 is concentric with the forging center.

[0027] The cooling system adopts internal circulating water cooling mode, and has high cooling efficiency. The frame assembly 13 is internally integrated with a cooling water flow channel formed by casting or machining. The core rod support flange 40 is internally machined with a channel which is respectively connected with the inner holes of the first cooling pipe 44 and the second cooling pipe 47. The first cooling pipe 44 and the second cooling pipe 47 are both seamless precision straight pipes, and the connection between the core rod support flange 40 and the first cooling pipe 44 and the second cooling pipe 47 and the connection between the first cooling pipe 44 and the second cooling pipe 47 are all thread sealing connections. The second cooling pipe 47 is also threadedly connected with the core rod inner pipe 50. The core rod assembly 7 itself is a coaxial double-layer sleeve structure, which is composed of a core rod outer pipe 49, a core rod inner pipe 50 and a sealing plug 51. The core rod outer pipe 49 is an outer working body participating in forging forming, is made of hot work die steel, and has a micro taper on the outer surface, so as to facilitate demolding with a high-temperature forged piece. The core rod inner pipe 50 is nested in the core rod outer pipe 49, and an annular gap is formed between the core rod outer pipe 49 and the core rod inner pipe 50. The core rod inner pipe 50 is machined with a plurality of through holes in the axial direction as water flow channels. The outer end of the sealing plug 51 is welded and sealed with the core rod outer pipe 49, and the inside of the sealing plug 51 is connected with the end of the core rod inner pipe 50 through threads, so as to seal the end of the core rod inner pipe 50.

[0028] The working path of the cooling water is as follows: the cooling water enters from the water inlet pipe joint 53 connected to the tail end of the frame assembly 13, flows through the flow channel in the frame assembly 13, the channel in the core rod support flange 40, the first cooling pipe 44 and the second cooling pipe 47, and reaches the core rod inner pipe 50. After flowing in the core rod inner pipe 50 to the front end thereof, the cooling water flows into the annular gap formed between the core rod inner pipe 50 and the core rod outer pipe 49 through the axial through holes on the core rod inner pipe 50, and flows back in the reverse direction in the axial direction. During the backflow process, the cooling water directly takes away the heat generated by the core rod outer pipe 49 due to forging friction and heat conduction. The heated cooling water successively flows through the annular cavities formed by the second core rod connecting pipe 48 and the second cooling pipe 47, the annular cavities formed by the first core rod connecting pipe 43 and the first cooling pipe 44, the internal flow channel of the flange sleeve 41 and the internal flow channel of the core rod support flange 40, and is finally discharged from the water return pipe joint 52 to enter the external circulating cooling system. The internal cooling structure can stably control the working temperature of the core rod below 150 DEG C, effectively preventing the core rod from softening at high temperature, thermal stress cracking and bonding with the forged piece.

[0029] In order to protect the equipment, the frame assembly 13 is integrally welded and formed by using Q355B low-alloy high-strength steel, and the strength of the welding seam is ensured through flaw detection. On both sides of the rear end of the frame assembly 13, stud type bumpers 54 are symmetrically installed. The bumper 54 integrates a rubber buffer head and a buffer spring, and when the frame assembly 13 moves to the stroke end point or an accidental collision occurs, the rubber buffer head can contact the limiting block on the slide rail 2 before the frame structure, and the impact energy is absorbed through the compression deformation of the buffer spring, so as to avoid damage to the key components such as the frame and the driving system caused by rigid collision.

[0030] The working process of the mandrel trolley is as follows: the hammer head position of the main machine is adjusted according to the pipe specification, the chuck 5 clamps one end of the pipe and starts to rotate. The hydraulic motor 11 of the mandrel trolley 1 drives the car frame assembly 13 to quickly advance along the slide rail 2 until the front end of the mandrel assembly 7 is aligned with the inner hole entrance of the thick-walled pipe 6. After the mandrel trolley 1 reaches the preset position, the clamping device 9 acts, the jaw 33 clamps the piston rod of the drive oil cylinder 4, and locking is realized. Subsequently, the drive oil cylinder 4 slowly pushes the mandrel trolley 1 and the mandrel assembly 7 into the pipe hole under the control of the electro-hydraulic proportional valve group, and the internal water cooling system starts. During the forging process, the chuck 5 drives the pipe to move axially, and the mandrel continuously and slowly feeds under the precise control of the drive oil cylinder 4, completing continuous forging. When the chuck moves to the front limit position, the forging stops. At this time, the clamping oil cylinder 30 is depressurized, the jaw 33 is opened, and the drive oil cylinder 4 is disconnected with the mandrel trolley 1. The hydraulic motor 11 is started in reverse, drives the mandrel trolley 1 to quickly retreat to the initial position with the mandrel assembly 7, and waits for the next working cycle. During the whole process, the position of the mandrel trolley 1 is detected at any time by the encoder 15 and fed back to the PLC control system, realizing accurate position control.

[0031] The above is only the preferred example of the present application. It should be noted that for those skilled in the art, under the technical inspiration provided by the present application, as the common knowledge in the mechanical field, other equivalent modifications and improvements can also be made, which should also be considered as the protection scope of the present application.

Claims

1. A mandrel carriage for precision forging of special thick-walled tubes, characterized in that, The vehicle includes a frame assembly (13), and a sliding component (28) is provided at the bottom of the frame assembly (13). The sliding component (28) is slidably engaged with the slide rail (2). A drive system is provided inside the slide rail (2). The drive system is connected to the sliding component (28) to drive the frame assembly (13) to rapidly feed and retract along the slide rail (2). Two sets of drive cylinders (4) are also symmetrically arranged on the slide rail (2). The cylinder barrels of the drive cylinders (4) are fixedly installed on the slide rail (2). The rear end of the frame assembly (13) is provided with two sets of clamping devices (9) for clamping and locking the piston rod of the drive cylinder (4) to the frame assembly (13); the frame assembly (13) is provided with a mandrel support flange (40) inside, which supports the mandrel assembly (7) and is concentric with the forging center of the radial forging machine. The rear of the frame assembly (13) is provided with a water pipe connector, and the frame assembly (13) has an integrated cooling water flow channel that connects the water pipe connector with the cooling chamber inside the mandrel assembly (7).

2. The mandrel carriage for precision forging of special thick-walled tubes according to claim 1, characterized in that: The drive system includes a hydraulic motor (11) and a sprocket drive structure. The sprocket drive structure includes a drive sprocket (18) and a driven sprocket (14). The output end of the hydraulic motor (11) is connected to the drive sprocket (18). The drive sprocket (18) and the driven sprocket (14) are driven together by a chain (12). The chain (12) is connected to the sliding assembly (28) at the bottom of the frame assembly (13).

3. A mandrel carriage for precision forging of special thick-walled tubes according to claim 1 or 2, characterized in that: The drive sprocket (18) is fitted onto the drive sprocket shaft (17) with an interference fit. One end of the drive sprocket shaft (17) is connected to the output shaft of the hydraulic motor (11) via a flat key, and the other end is assembled and connected to the slide rail (2) via a spherical roller thrust bearing (19) and a bearing end cover (20). The driven sprocket (14) is mounted on the driven sprocket shaft (22) via two sets of single-row roller bearings (23).

4. A mandrel carriage for precision forging of special thick-walled tubes according to claim 3, characterized in that: The driven sprocket shaft (22) is installed in the sprocket tensioning device, which includes an adjusting bracket (24), a support plate (21), an adjusting screw (26), and a nut (27). The support plate (21) is welded and fixed on the slide rail (2). One end of the adjusting screw (26) is equipped with a nut (27), and the other end passes through the adjusting bracket (24). By rotating the nut (27), the adjusting screw (26) is pushed to move, thereby driving the adjusting bracket (24) to tighten the chain (12).

5. A mandrel carriage for precision forging of special thick-walled tubes according to claim 4, characterized in that: The clamping device (9) adopts a scissor arm structure, including a first clamping arm (32), a second clamping arm (35), a pin (31), a clamping cylinder (30), and jaws (33); the first clamping arm (32) and the second clamping arm (35) are hinged to the frame assembly (13) through the pin (31), the cylinder end of the clamping cylinder (30) is hinged to the second clamping arm (35), the piston rod end is hinged to the first clamping arm (32), and the jaws (33) are installed at the ends of the first clamping arm (32) and the second clamping arm (35).

6. A mandrel carriage for precision forging of special thick-walled tubes according to claim 5, characterized in that: The mandrel support flange (40) is connected to the first mandrel connecting pipe (43) through the flange sleeve (41), and the first mandrel connecting pipe (43) is connected to the mandrel outer pipe (49) through the second mandrel connecting pipe (48); the cooling water flow channel includes an inlet pipe joint (53) and a return pipe joint (52), and the inlet pipe joint (53) is connected to the mandrel inner pipe (50) in sequence through the first cooling pipe (44) and the second cooling pipe (47), and an annular return cavity is formed between the mandrel inner pipe (50) and the mandrel outer pipe (49).

7. A mandrel carriage for precision forging of special thick-walled tubes according to claim 6, characterized in that: The inner tube (50) of the mandrel is provided with multiple water flow channels arranged axially, and a sealing plug (51) is welded to one end of the outer tube (49) of the mandrel. The sealing plug (51) is connected to the inner tube (50) of the mandrel through threads.

8. A mandrel carriage for precision forging of special thick-walled tubes according to claim 7, characterized in that: The rear sides of the frame assembly (13) are symmetrically arranged and fixedly installed with stud-type buffers (54), which are equipped with rubber buffer heads and buffer springs.

9. A mandrel carriage for precision forging of special thick-walled tubes according to claim 8, characterized in that: The frame assembly (13) is formed by welding Q355B low alloy high strength steel, and the drive cylinder (4) is equipped with a hydraulic valve group, which is an electro-hydraulic proportional valve group.

10. A mandrel carriage for precision forging of special thick-walled tubes according to claim 9, characterized in that: The outer surface of the mandrel outer tube (49) of the mandrel assembly (7) is designed with a micro-taper; the drive system is equipped with an encoder (15) for detecting the position of the frame assembly (13); a proximity switch (34) for monitoring clamping and releasing actions is provided next to the first clamping arm (32) and the second clamping arm (35) of the clamping device (9).

Images