Socket and spigot type pipe end expanding equipment

Abstract

The utility model discloses socket type pipe end expanding equipment which comprises a machine base and a shaping die assembly, the shaping die assembly comprises a plurality of shaping modules, and the shaping die assembly further comprises a vertical fixed plate installed on the machine base and a vertical movable plate connected with the fixed plate in a sliding mode. The movable driving oil cylinder is used for driving the movable plate to move back and forth relative to the fixed plate; and the shaping module is detachably mounted on the inner side of the shaping mold base. The movable plate is pushed to move by moving the driving oil cylinder, the movable plate pulls or pushes the shaping die holder and the shaping module to move along the first radial guide groove through the first guide key, all transmission links are in rigid connection and sliding contact and do not depend on an elastic element, and therefore it is guaranteed that the shaping module can return normally and be separated from a steel pipe in time. The device also has the advantages of being capable of processing steel pipes with different inner diameters, convenient to install and debug, stable in action and the like.

Description

Technical Field

[0001] This utility model relates to a pipe end expansion device. Background Technology

[0002] The socket-type pipe end expanding equipment mainly consists of a shaping mold assembly (outer mold assembly) and an expanding mold assembly (inner mold assembly). During operation, the inner mold assembly expands the pipe end from the inside, while the outer mold closes and squeezes the outside of the steel pipe, thus achieving the pipe end expansion and forming. After the expansion is completed, the inner mold assembly contracts, and the outer mold assembly returns to its original position under the action of a tension spring.

[0003] However, in actual production, the shaping module of the outer mold assembly is often difficult to return to its original position smoothly due to the clamping and pressing with the steel pipe, relying solely on the tension spring. On the other hand, the shaping module is directly connected to the return mechanism, making it impossible to replace different specifications of shaping modules according to the pipe diameter. Utility Model Content

[0004] This utility model proposes a socket-type pipe end expansion device, the purpose of which is to: 1. solve the problem that the shaping module is difficult to separate smoothly from the steel pipe; 2. solve the problem that the shaping module assembly cannot adapt to steel pipes of different specifications.

[0005] The technical solution of this utility model is as follows:

[0006] A socket-type pipe end expansion device includes a base and a shaping mold assembly. The shaping mold assembly includes several shaping modules, a vertical fixed plate mounted on the base, a vertical movable plate slidably connected to the fixed plate, a moving drive cylinder for driving the movable plate to move back and forth relative to the fixed plate, and several shaping mold seats corresponding one-to-one with the shaping modules. The shaping modules are detachably mounted on the inner side of the shaping mold seats.

[0007] The movable plate is provided with a tapered first through hole, and the wall of the first through hole is evenly distributed with first oblique guide grooves around its circumference; the shaping mold base is evenly distributed in the first through hole, and the shaping mold base is provided with a first inclined surface that contacts and cooperates with the first through hole, and a first guide key that cooperates with the first oblique guide groove is installed on the first inclined surface;

[0008] The fixing plate is provided with a second through hole, and a plurality of first radial guide grooves are evenly distributed around the second through hole. The shaping mold base is equipped with a second guide key that cooperates with the first radial guide grooves.

[0009] As a further improvement to the socket-type pipe end expansion device: the moving drive cylinders are in four sets, evenly distributed on the moving plate;

[0010] The hydraulic station of the socket-type pipe end expansion device includes a first synchronous valve, a second synchronous valve, and a third synchronous valve. The inlet of the first synchronous valve is used to introduce hydraulic oil. The first outlet and the second outlet of the first synchronous valve are respectively connected to the inlet of the second synchronous valve and the inlet of the third synchronous valve. The two outlets of the second synchronous valve and the two outlets of the third synchronous valve are respectively connected to the oil circuit connection port of the oil chamber on the same side of the four moving drive cylinders.

[0011] As a further improvement to the socket-type pipe end expansion device, the hydraulic station also includes an oil pump, a relief valve, and a solenoid directional valve.

[0012] The output end of the oil pump is connected to the oil tank via an overflow valve and also to the P port of the solenoid directional valve; the T port of the solenoid directional valve is connected to the oil tank, the A port is connected to the input port of the first synchronous valve, and the B port is simultaneously connected to the oil circuit connection port of the other side oil chamber of the four moving drive cylinders.

[0013] As a further improvement to the socket-type pipe end expansion device: the shaping mold assembly also includes a guide rod, one end of which is fixed to a fixed plate or a movable plate, and the other end is slidably engaged with the movable plate or the fixed plate.

[0014] As a further improvement to the socket-type pipe end expansion device: the moving plate is connected to the fixed plate via a slider guide rail.

[0015] As a further improvement to the socket-type pipe end expansion device, it also includes a main hydraulic cylinder and an expansion mold assembly mounted on the machine base;

[0016] The main hydraulic cylinder is horizontally positioned and is used to drive the expansion mold assembly to expand the inner diameter of the tube end.

[0017] As a further improvement to the socket-type pipe end expansion device: the main oil cylinder and the expansion mold assembly are mounted on the machine base via a rotary displacement mechanism.

[0018] As a further improvement to the socket-type pipe end expansion device: the expansion mold assembly includes a conical body, and the conical body has second oblique guide grooves evenly distributed around its circumference;

[0019] The expansion mold assembly also includes a disc body fixedly disposed relative to the cylinder body of the main oil cylinder. The disc body is provided with a third through hole, and a plurality of second radial guide grooves are evenly distributed around the circumference of the third through hole.

[0020] The expansion mold assembly also includes several sets of one-to-one corresponding expansion mold bases and expansion modules. The expansion modules are detachably mounted on the outer surface of the expansion mold base. The expansion mold base is provided with a second inclined surface that matches the conical surface of the cone. A third guide key that matches the second inclined guide groove is installed on the second inclined surface. The expansion mold base is also provided with a fourth guide key that matches the second radial guide groove.

[0021] The piston rod of the main cylinder passes through the third through hole, the second through hole and the first through hole in sequence from back to front, and its end is connected to the conical body.

[0022] As a further improvement to the socket-type pipe end expansion device: the main hydraulic cylinder and the expansion mold assembly are mounted on the machine base via a rotary displacement mechanism;

[0023] The rotary displacement mechanism includes a fixed frame and a rotating cylinder;

[0024] The fixed frame is mounted on the machine base; the axis of the rotating cylinder is horizontally set, and its front and rear ends are respectively connected to the fixed frame through bearings; the cylinder body of the main oil cylinder is mounted on the rear end of the rotating cylinder, and the piston rod passes through the rotating cylinder; the disc body is mounted on the front end of the rotating cylinder.

[0025] The rotary positioning mechanism also includes a rotary positioning drive device for driving the rotary cylinder to rotate.

[0026] As a further improvement to the socket-type pipe end expansion device: the rotary displacement drive device is a rotary displacement drive cylinder, one end of which is rotatably connected to the fixed seat and the other end is rotatably connected to the rotating cylinder.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This utility model uses a moving drive cylinder to push the moving plate to move. The moving plate pulls or pushes the shaping mold base and the shaping module to move along the first radial guide groove through the first guide key. All transmission links are rigid connections and sliding contacts, without relying on elastic elements, thereby ensuring that the shaping module can return to its normal position and disengage from the steel pipe in time.

[0029] 2. The shaping module is installed on the shaping mold base in a detachable manner, and can be replaced at any time according to the specifications of the steel pipe.

[0030] 3. The shaping mold assembly in this utility model is an independent module and there is no direct mechanical connection between it and the expanding mold. It can be completely removed by removing the connection between the fixing plate and the machine base, which is convenient for maintenance and debugging.

[0031] 4. This utility model uses four moving drive cylinders to drive the moving plate to move, which makes the force more even, the size smaller, and the cost lower.

[0032] 5. The hydraulic station of this utility model uses three synchronous valves to form a two-stage flow distribution mechanism to ensure that the oil volume in the four moving drive cylinders is always equal and moves synchronously, thus avoiding blockage of the mold base during sliding due to the non-parallelism between the moving plate and the fixed plate. Attached Figure Description

[0033] Figure 1 This is a perspective view of the present utility model;

[0034] Figure 2 This is a side view of the present invention;

[0035] Figure 3 This is a cross-sectional view of the present invention;

[0036] Figure 4 for Figure 3 Enlarged view of section A;

[0037] Figure 5 A three-dimensional view of the mold assembly;

[0038] Figure 6 This is a sectional view of the mold assembly;

[0039] Figure 7 This is a hydraulic schematic diagram of the part of the hydraulic station that enables the synchronous movement of four moving drive cylinders.

[0040] The reference numerals in the figures include:

[0041] 1. Base, 2. Hydraulic station, 3. Main cylinder, 4. Fixed frame, 5. Rotating cylinder, 6. Shaping mold assembly, 7. Expanding mold assembly, 8. Rotary displacement drive cylinder, 9. Bearing, 2-1. Oil pump, 2-2. Overflow valve, 2-3. Solenoid directional valve, 2-4. First synchronization valve, 2-5. Second synchronization valve, 2-6. Third synchronization valve, 6-1. Fixed plate, 6-2. Moving plate, 6-3. Guide rod, 6-4. Moving drive cylinder, 6-5. First guide key, 6-6. Shaping mold base, 6-7. Second guide key, 6-8. Shaping module, 6-9. Slider guide rail, 7-1. Conical body, 7-2. Third guide key, 7-3. Expanding mold base, 7-4. Fourth guide key, 7-5. Expanding module, 7-6. Disc. Detailed Implementation

[0042] The technical solution of this utility model will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments.

[0043] like Figure 1 , 23. A socket-type pipe end expansion device, including a base 1, on which a shaping mold assembly 6, an expansion mold assembly 7, a main oil cylinder 3, a hydraulic station 2, and an instrument cabinet are installed.

[0044] like Figure 4 , 5 6. The shaping mold assembly 6 includes a vertical fixed plate 6-1 mounted on the base 1, a vertical movable plate 6-2 slidably connected to the fixed plate 6-1 via a slider guide rail 6-9 and a guide rod 6-3, a movable drive cylinder 6-4 for driving the movable plate 6-2 to move back and forth relative to the fixed plate 6-1, a plurality of (8-24) shaping modules 6-8, and a plurality of shaping mold bases 6-6 corresponding one-to-one with the shaping modules 6-8.

[0045] Specifically, the guide rods 6-3 are in multiple sets, with one end fixed to the fixed plate 6-1 or the movable plate 6-2, and the other end slidingly engaged with the movable plate 6-2 or the fixed plate 6-1.

[0046] The slider in the slider guide rail 6-9 is connected to the bottom of the moving plate 6-2, and the guide rail is installed on the horizontal base plate of the fixed plate 6-1.

[0047] The movable drive cylinders 6-4 are in four groups, evenly distributed on the movable plate 6-2 (in this embodiment, they are located at the four right-angle vertices). The cylinder body of the movable drive cylinder 6-4 is fixed on the movable plate 6-2, and the piston rod is connected to the fixed plate 6-1. When the movable drive cylinder 6-4 extends or retracts, it will drive the movable plate 6-2 to move back and forth relative to the fixed plate 6-1.

[0048] To ensure the synchronized movement of the four sets of moving drive cylinders 6-4, and to ensure the smooth movement of the moving plate 6-2 and its constant parallelism with the fixed plate 6-1, the hydraulic station 2 also implements a synchronization mechanism based on a synchronization valve. Specifically, as follows... Figure 7The hydraulic station 2 includes an oil pump 2-1, a relief valve 2-2, and a solenoid directional valve 2-3, as well as a first synchronizing valve 2-4, a second synchronizing valve 2-5, and a third synchronizing valve 2-6. The output end of the oil pump 2-1 is connected to the oil tank via the relief valve 2-2 to ensure stable oil pressure, and is also connected to the P port of the solenoid directional valve 2-3. The T port of the solenoid directional valve 2-3 is connected to the oil tank for oil return, the A port is connected to the input port of the first synchronizing valve 2-4, and the B port is simultaneously connected to the oil circuit connection ports of the rodless chambers of the four moving drive cylinders 6-4. Further, the first and second output ports of the first synchronizing valve 2-4 are respectively connected to the input ports of the second synchronizing valve 2-5 and the third synchronizing valve 2-6, and the two output ports of the second synchronizing valve 2-5 and the two output ports of the third synchronizing valve 2-6 are respectively connected to the oil circuit connection ports of the rod chambers of the four moving drive cylinders 6-4. By controlling the operation of the solenoid directional valve 2-3, the reversing and extension control of the four sets of moving drive cylinders 6-4 can be achieved. Whether extending or retracting, the hydraulic oil must pass through three synchronization valves to ensure that the four sets of moving drive cylinders 6-4 move synchronously.

[0049] Furthermore, such as Figure 4 , 5 6. The movable plate 6-2 is provided with a tapered first through hole, and the wall of the first through hole is circumferentially distributed with first oblique guide grooves. The shaping mold base 6-6 is circumferentially distributed in the first through hole, and the shaping mold base 6-6 is provided with a first inclined surface that contacts and cooperates with the first through hole. A first guide key 6-5 that cooperates with the first oblique guide groove is installed on the first inclined surface.

[0050] The fixing plate 6-1 is provided with a second through hole, and a plurality of first radial guide grooves are evenly distributed around the second through hole. The shaping mold base 6-6 is equipped with a second guide key 6-7 that cooperates with the first radial guide grooves.

[0051] When the moving plate 6-2 moves back and forth relative to the fixed plate 6-1, the first oblique guide groove drives the shaping mold base 6-6 to move along the first radial guide groove through the first guide key 6-5, thereby realizing the synchronous closing or separation of all shaping mold bases 6-6.

[0052] The shaping module 6-8 is installed on the inside of the shaping mold base 6-6 in a detachable manner (bolted connection) for easy replacement.

[0053] Furthermore, the main hydraulic cylinder 3 is horizontally positioned to drive the expansion mold assembly 7 to expand the inner diameter of the tube end.

[0054] The expansion mold assembly 7 includes a cone-shaped body 7-1, and second oblique guide grooves are evenly distributed on the circumference of the cone surface of the cone-shaped body 7-1.

[0055] The expansion mold assembly 7 also includes a disc 7-6 fixedly disposed relative to the cylinder body of the main oil cylinder 3. The disc 7-6 is provided with a third through hole, and a plurality of second radial guide grooves are evenly distributed around the third through hole.

[0056] The expanding mold assembly 7 further includes several sets of corresponding expanding mold bases 7-3 and expanding modules 7-5. The expanding modules 7-5 are detachably mounted on the outer surface of the expanding mold bases 7-3. The expanding mold bases 7-3 are provided with a second inclined surface that mates with the conical surface of the conical body 7-1. A third guide key 7-2 that mates with a second inclined guide groove is installed on the second inclined surface. The expanding mold bases 7-3 are also provided with a fourth guide key 7-4 that mates with a second radial guide groove.

[0057] The piston rod of the main hydraulic cylinder 3 passes sequentially from back to front through the third through hole, the second through hole, and the first through hole, and its end connects to the conical body 7-1. When the piston rod of the main hydraulic cylinder 3 moves backward, the conical surface of the conical body 7-1 pushes the expanding mold base 7-3 to move outward along the second radial guide groove, realizing mold expansion. When the piston rod of the main hydraulic cylinder 3 moves forward, the conical body 7-1 pulls the expanding mold base 7-3 inward along the second radial guide groove via the third guide key 7-2, thereby moving it away from the inner surface of the tube end.

[0058] The guide key is preferably a T-shaped key, which serves both a guiding and limiting function, ensuring that the mold base does not disengage from the contacting conical or flat surface, thereby providing tensile force during return. Alternatively, the guide key may have a dovetail-shaped cross-section, or other shapes that serve both guiding and limiting functions.

[0059] Furthermore, the main hydraulic cylinder 3 and the expansion mold assembly 7 are mounted on the machine base 1 via a rotary displacement mechanism.

[0060] The rotational displacement mechanism includes a fixed frame 4 and a rotating cylinder 5.

[0061] The fixed frame 4 is mounted on the base 1. The axis of the rotating cylinder 5 is horizontally set, and its front and rear ends are connected to the fixed frame 4 through bearings 9 respectively. The cylinder body of the main oil cylinder 3 is mounted on the rear end of the rotating cylinder 5, and the piston rod passes through the rotating cylinder 5. The disc body 7-6 is mounted on the front end of the rotating cylinder 5.

[0062] The rotary positioning mechanism also includes a rotary positioning drive device for driving the rotary cylinder 5 to rotate. In this embodiment, the rotary positioning drive device is a rotary positioning drive cylinder 8, one end of which is rotatably connected to the fixed base and the other end is rotatably connected to the rotary cylinder 5. When the rotary positioning drive cylinder 8 extends or retracts, it will drive the rotary cylinder 5, the main cylinder 3, and the expansion mold assembly 7 to rotate synchronously by an angle.

[0063] The working process of this device is as follows:

[0064] Before processing, the piston rod of the main hydraulic cylinder 3 is fully extended, and the expanding mold assembly 7 is closed. Simultaneously, the piston rod of the moving drive cylinder 6-4 extends, separating the fixed plate 6-1 and the moving plate 6-2, thus separating the shaping mold assembly 6. During processing, the steel pipe enters from the larger end of the cone until the expanding module 7-5 is fully inside the steel pipe, reaching the designated position, at which point the steel pipe stops moving. At this point, the moving drive cylinder 6-4 retracts, causing the moving plate 6-2 to move towards the fixed plate 6-1. Then, through the cooperation of the first through hole and the first inclined surface, it pushes the shaping mold base 6-6 and the shaping module 6-8 to move inward and retract, closing the shaping module 6-8 into place. Then, the main hydraulic cylinder 3 begins to retract its piston rod, causing the cone 7-1 to move backward. The cone 7-1 then, through the second inclined surface, causes the expanding mold base 7-3 and the expanding module 7-5 to expand radially, thereby increasing the diameter of the steel pipe end. The processing is not a single expansion molding but rather several stages. For example, when the expansion reaches 1 / 3 of the way in the first expansion, the main hydraulic cylinder 3 extends and pulls back the expansion mold base 7-3 through the third guide key 7-2, causing the expansion module 7-5 to detach from the inner wall of the steel pipe. Then, the rotation displacement drive cylinder 8 moves, extending (or retracting) a certain distance. The rotating cylinder 5, the main hydraulic cylinder 3, and the expansion mold assembly 7 rotate at a certain angle. Then, the main hydraulic cylinder 3 retracts again, and the expansion reaches 2 / 3 of the way in the second expansion by controlling the movement distance of the piston rod. The above rotation action is repeated until the expansion is in place. At this time, the outer wall of the steel pipe is in close contact with the shaping module 6-8.

[0065] After the expansion is completed, the moving drive cylinder 6-4 extends, causing the moving plate 6-2 to move in the opposite direction and away from the fixed plate 6-1. Then, the first guide key 6-5 pulls the shaping module 6-8 apart from the steel pipe. Finally, the main cylinder 3 extends completely, driving the expansion module 7-5 to close and detach from the inner wall of the steel pipe, and then other equipment removes the steel pipe.

[0066] Based on this equipment, steel pipes of different diameters can also be processed by replacing different expansion modules 7-5 and shaping modules 6-8.

[0067] It should be noted that, as will be apparent to those skilled in the art, this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this utility model. The scope of this utility model is defined by the claims rather than the foregoing description.

Claims

1. A socket pipe end expanding apparatus comprising a base (1) and a sizing die assembly (6) comprising a plurality of sizing die blocks (6-8), characterised in that: The sizing mold assembly (6) further comprises a vertical fixed plate (6-1) mounted on the base (1), a vertical moving plate (6-2) in sliding connection with the fixed plate (6-1), a moving drive oil cylinder (6-4) for driving the moving plate (6-2) to move forward and backward relative to the fixed plate (6-1), and a plurality of sizing mold seats (6-6) corresponding to the sizing mold blocks (6-8) one by one; the sizing mold blocks (6-8) are detachably mounted on the inner side of the sizing mold seats (6-6); The moving plate (6-2) is provided with a conical first through hole, and the hole wall of the first through hole is circumferentially provided with first inclined guide grooves; the sizing mold seats (6-6) are circumferentially distributed in the first through hole, and the sizing mold seats (6-6) are provided with first inclined surfaces in contact with the first through hole, and the first inclined surfaces are provided with first guide keys (6-5) matched with the first inclined guide grooves; The fixed plate (6-1) is provided with a second through hole, and the periphery of the second through hole is circumferentially provided with a plurality of first radial guide grooves, and the sizing mold seats (6-6) are provided with second guide keys (6-7) matched with the first radial guide grooves.

2. The bell and spigot pipe end expanding apparatus as claimed in claim 1, wherein: The moving drive oil cylinder (6-4) is four groups, which are uniformly distributed on the moving plate (6-2); The hydraulic station (2) of the bell and spigot pipe end expanding equipment comprises a first synchronization valve (2-4), a second synchronization valve (2-5) and a third synchronization valve (2-6); the input port of the first synchronization valve (2-4) is used for inputting hydraulic oil, the first output port and the second output port of the first synchronization valve (2-4) are respectively connected with the input ports of the second synchronization valve (2-5) and the third synchronization valve (2-6), and the two output ports of the second synchronization valve (2-5) and the two output ports of the third synchronization valve (2-6) are respectively connected with the oil path connection ports of the same side oil chambers of the four moving drive oil cylinders (6-4).

3. The bell and spigot pipe end expanding apparatus as defined in claim 2 wherein: The hydraulic station (2) further comprises an oil pump (2-1), an overflow valve (2-2) and an electromagnetic reversing valve (2-3); The output end of the oil pump (2-1) is connected to the oil tank through the overflow valve (2-2) and is connected with the P port of the electromagnetic reversing valve (2-3); the T port of the electromagnetic reversing valve (2-3) is connected with the oil tank, the A port is connected with the input port of the first synchronization valve (2-4), and the B port is connected with the oil path connection ports of the other side oil chambers of the four moving drive oil cylinders (6-4) at the same time.

4. The bell and spigot pipe end expanding apparatus as defined in claim 1 wherein: The sizing mold assembly (6) further comprises a guide rod (6-3), one end of the guide rod (6-3) is fixed on the fixed plate (6-1) or the moving plate (6-2), and the other end is in sliding connection with the moving plate (6-2) or the fixed plate (6-1).

5. The bell and spigot pipe end expanding apparatus as defined in claim 1 wherein: The moving plate (6-2) is connected with the fixed plate (6-1) through a sliding block guide rail (6-9).

6. The bell and spigot pipe end expanding apparatus as defined in claim 1 wherein: Further comprising a main oil cylinder (3) and a swaging mold assembly (7) mounted on the base (1); The main oil cylinder (3) is horizontally arranged and used for driving the swaging mold assembly (7) to perform the swaging operation on the inner diameter of the pipe end.

7. The bell and spigot pipe end expanding apparatus as defined in claim 6 wherein: The main oil cylinder (3) and the swaging mold assembly (7) are mounted on the base (1) through a rotary displacement mechanism.

8. The bell and spigot pipe end expanding apparatus as defined in claim 6 wherein: The inflation die assembly (7) comprises a conical body (7-1), and the conical surface of the conical body (7-1) is circumferentially and evenly provided with second inclined guide grooves; The inflation die assembly (7) further comprises a disc body (7-6) fixedly arranged relative to the cylinder body of the main oil cylinder (3), and the disc body (7-6) is provided with a third through hole, and the periphery of the third through hole is circumferentially and evenly provided with a plurality of second radial guide grooves; The inflation die assembly (7) further comprises a plurality of groups of corresponding inflation die seats (7-3) and inflation die blocks (7-5), the inflation die blocks (7-5) are detachably arranged on the outer surfaces of the inflation die seats (7-3); the inflation die seats (7-3) are provided with second inclined surfaces matched with the conical surface of the conical body (7-1), the second inclined surfaces are provided with third guide keys (7-2) matched with the second inclined guide grooves, and the inflation die seats (7-3) are further provided with fourth guide keys (7-4) matched with the second radial guide grooves; The piston rod of the main oil cylinder (3) sequentially passes through the third through hole, the second through hole and the first through hole from back to front, and the tail end is connected with the conical body (7-1).

9. The bell and spigot pipe end expanding apparatus as defined in claim 8 wherein: The main oil cylinder (3) and the inflation die assembly (7) are arranged on the machine base (1) through a rotary displacement mechanism; The rotary displacement mechanism comprises a fixed frame (4) and a rotary cylinder (5); The fixed frame (4) is arranged on the machine base (1), the axis of the rotary cylinder (5) is horizontally arranged, and the front and rear ends of the rotary cylinder (5) are connected with the fixed frame (4) through bearings (9), respectively; the cylinder body of the main oil cylinder (3) is arranged at the rear end of the rotary cylinder (5), and the piston rod passes through the rotary cylinder (5); and the disc body (7-6) is arranged at the front end of the rotary cylinder (5). The rotary displacement mechanism further comprises a rotary displacement driving device for driving the rotary cylinder (5) to rotate.

10. The bell and spigot pipe end expanding apparatus as defined in claim 9 wherein: The rotary displacement driving device is a rotary displacement driving oil cylinder (8), one end of the rotary displacement driving oil cylinder (8) is rotationally connected with the fixed seat, and the other end is rotationally connected with the rotary cylinder (5).

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