Method and device for polishing and strengthening inner surface of variable-diameter elbow

Abstract

The invention discloses a method and device for polishing and strengthening the inner surface of a variable-diameter elbow, and relates to the field of polishing equipment, the variable-diameter elbow and piston cylinders located at the two ends of the variable-diameter elbow are included, and the piston cylinders comprise the left piston cylinder and the right piston cylinder; a first piston, a second piston and a third piston are arranged in the left piston cylinder, the first piston is independently arranged in the left piston cylinder, the second piston and the third piston are oppositely arranged in the left piston cylinder, and the left piston cylinder is further provided with a water flow inlet and a grinding material flow inlet. A fourth piston, a fifth piston and a sixth piston are arranged in the right piston cylinder, the sixth piston is independently arranged in the right piston cylinder, the fourth piston and the fifth piston are oppositely arranged in the right piston cylinder, and the right piston cylinder is further provided with a water flow outlet and a grinding material flow outlet. A mold is arranged in the variable-diameter bent pipe, the shape of the mold is subjected to profiling machining according to the shape of the variable-diameter bent pipe, the radial section width between the variable-diameter bent pipe and the mold is controlled through the mold, and uniform polishing is achieved.

Description

Technical Field

[0001] The invention relates to the field of polishing equipment, in particular to a method and a device for polishing and strengthening the inner surface of a variable-diameter elbow. Background Art

[0002] For bent pipes, especially those with variable diameters, in order to achieve the inner surface processing accuracy requirements, it is necessary to polish and strengthen the inner surface. However, for bent pipes, especially those with variable diameters, the inner surface polishing and strengthening are difficult due to their small aperture and long internal depth. Therefore, a device is urgently needed to achieve polishing and strengthening of the inner surface of the variable diameter bent pipe.

[0003] Cavitation technology generates steam bubbles or gas-filled cavities by making the pressure inside the fluid lower than the saturated vapor pressure. The local high pressure generated by the collapse of the cavitation bubble can produce mechanical impact on the surface of the material, further causing plastic deformation of the surface of the material, thereby increasing the strength of the material. In addition, local high temperature will be generated at the moment of cavitation collapse, which can induce thermal effects on the surface of the material, promote changes in the surface microstructure, and help strengthen the material.

[0004] The Chinese patent publication number is CN118404414A, and the document named "A magnetic grinding device and method for processing the inner surface of a catheter" proposes a grinding device for processing the inner surface of a catheter, including a base, a manipulator disposed on the base and a fixed clamping component, and a polishing mechanism on the manipulator. The polishing mechanism includes a base disposed at the gripper of the manipulator, and a connecting seat detachably disposed on the base and fixed to the gripper of the manipulator. Precision grinding can be achieved to remove defects on the inner surface of the catheter, reducing the manufacturing and maintenance costs of grinding the inner wall of the pipeline. However, the equipment can only polish the inner surface of the pipeline, and subsequent surface strengthening is still required to improve the mechanical properties of the pipeline.

[0005] The Chinese patent publication number is CN115741486B, and the document named "Ultrasonic Assisted Nano-abrasive Water Jet Groove Heat Pipe Inner Surface Composite Polishing Device and Method" proposes a nano-abrasive water jet groove heat pipe inner surface composite polishing device assisted by ultrasound, including a driving device, a spraying device, an ultrasonic device and an ultrasonic polishing platform. The driving device is connected to the spraying device and is used to drive the spraying device to rotate eccentrically; the spraying device is used to form a polishing liquid to polish the inner surface of the groove heat pipe; the ultrasonic device is fixed on the ultrasonic polishing platform to achieve efficient composite polishing of the groove heat pipe to be processed. Trace material removal can be achieved, and the polishing effect is stable. However, when processing a variable diameter elbow, since the variable diameter elbow changes its diameter in the cross-sectional direction, the water jet will accumulate in the deeper part of the concave, causing the cavitation to collapse before reaching the inner wall surface, and finally the polishing enhancement effect is uneven when processing the variable diameter elbow. Summary of the invention

[0006] The object of the present invention is to provide a method and device for polishing and strengthening the inner surface of a variable diameter elbow to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a device for polishing and strengthening the inner surface of a variable diameter elbow, comprising a variable diameter elbow and piston cylinders located at both ends of the variable diameter elbow, wherein the piston cylinder is divided into a left piston cylinder and a right piston cylinder;

[0008] The left piston cylinder is provided with piston 1, piston 2 and piston 3, wherein the piston 1 is arranged alone in the left piston cylinder, and the piston 2 and piston 3 are arranged relatively in the left piston cylinder, and the left piston cylinder is also provided with a water inlet and an abrasive inlet;

[0009] The right piston cylinder is provided with piston 4, piston 5 and piston 6, the piston 6 is separately provided in the right piston cylinder, the piston 4 and piston 5 are arranged relatively in the right piston cylinder, and the right piston cylinder is also provided with a water outlet and an abrasive outlet;

[0010] A mold is arranged inside the reducer bend, and the shape of the mold is processed according to the shape of the reducer bend. The width of the interval between the inner wall of the reducer bend and the outer wall of the mold increases as the inner diameter of the reducer bend decreases.

[0011] Preferably, a valve 1 is provided in the water inlet, and a valve 2 is provided in the abrasive inlet.

[0012] Preferably, the left piston cylinder is fixedly connected to the flange plate 2 on the reducer elbow via the flange plate 1, and a flange plate 5 for sealing is provided between the flange plate 1 and the flange plate 2.

[0013] Preferably, the right piston cylinder is fixedly connected to flange three on the reducer elbow via flange four.

[0014] Preferably, a valve three is provided in the water outlet, and a valve four is provided in the abrasive outlet.

[0015] Preferably, the flange plate five is fixedly connected to the root of the mold, and a through hole is arranged on the flange plate five.

[0016] A method for polishing and strengthening the inner surface of a variable diameter elbow comprises the following steps:

[0017] S1. The piston is driven by an external controller to move to a maximum stroke of the piston, which is between the water inlet and the abrasive inlet, and the piston is driven to the maximum stroke of the piston six, which is between the water outlet and the abrasive outlet;

[0018] S2. Open the control valve 2 and valve 4 of the abrasive flow inlet and abrasive flow outlet pipelines. Under the action of the external supply device, the abrasive flow enters the working chamber of the left piston cylinder from the abrasive flow inlet and enters the gap between the reducer elbow and the mold. During the flow of the abrasive flow, the inner surface of the reducer elbow is polished. Finally, the excess abrasive flow is discharged through the abrasive flow outlet under the action of pressure.

[0019] S3. Close the control valve 2 and valve 4 of the abrasive flow inlet and abrasive flow outlet pipes to stop the filling of the abrasive flow;

[0020] S4. The piston is driven to move to the minimum stroke by an external controller, and the control valve of the water inlet pipe is opened to inject water into the working chamber of the left piston cylinder;

[0021] S5. At this time, piston 1 is at the minimum stroke, and piston 6 is at the minimum stroke, so that the working chamber volume of the left piston cylinder and the right piston cylinder is as large as possible. After injecting an appropriate volume of internal water flow, the piston 1 and piston 6 reciprocate in the same direction and frequency. When piston 1 is compressed to the minimum stroke, piston 6 is stretched to the maximum stroke at the same time. When piston 1 is stretched to the maximum stroke, piston 6 is compressed to the minimum stroke at the same time. In the left piston cylinder, pistons 2 and 3 reciprocate in the same direction and frequency, and in the right piston cylinder, pistons 4 and 5 reciprocate in the same direction and frequency, so that the internal water flow and the abrasive flow are evenly mixed;

[0022] S6. Then open the control valve of the abrasive outlet pipe to discharge part of the mixed liquid;

[0023] S7. Control piston 1 to the minimum stroke, and the other pistons to the maximum stroke. Open control valve 1 of the water inlet pipe, and close all valves after the water is filled.

[0024] S8. Control piston 6 to move toward the minimum stroke, control piston 2, piston 3, piston 4, and piston 5 to move toward the minimum stroke synchronously, and reduce the pressure in the working chamber of the left piston cylinder, the right piston cylinder, and the reducer elbow to below the saturated steam pressure, thereby generating cavitation bubbles through cavitation;

[0025] S9. After piston 1 and piston 6 reach the minimum stroke, all pistons are controlled to move toward the maximum stroke again. At this time, the pressure rises to collapse the cavitation bubbles and release energy, so that the abrasive flow and the water flow interact with each other to strengthen the inner surface;

[0026] S10. Control all pistons to repeat the above movement, generate cavitation when the piston is compressed to the minimum stroke, and collapse the cavitation when the piston is stretched to the maximum stroke, thereby strengthening the inner surface;

[0027] S11. Then open the control valve 4 of the abrasive outlet pipe, and piston 1 and piston 6 reciprocate in the same direction and frequency under control to discharge the mixed liquid, complete the strengthening, and remove the reducer elbow.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention manufactures specific molds for different reducer elbows to control the radial cross-sectional area between the reducer elbow and the mold to increase as the inner diameter of the reducer elbow decreases. The radial cross-sectional area between the reducer elbow and the mold increases as the inner diameter of the reducer elbow decreases, ensuring that the abrasive flow has the same speed and pressure at any point on the inner surface. Ultimately, the inner surface of the elbow to be processed is subjected to the same force from the abrasive flow, avoiding a large stress concentration caused by the abrasive flow in a certain part of the pipe, and achieving uniform polishing of the inner surface;

[0030] 2. The present invention changes the volume of the working chamber, the reducer elbow and the gap between the molds by controlling the closing degree of different pistons in combination, and processes a specific mold, and finally realizes uniform passage of the abrasive flow in the reducer elbow. It avoids the problem of incomplete processing on one side of the inner surface of the elbow or excessive processing on the other side in traditional polishing, realizes polishing of the inner surface of the reducer elbow in radial and axial directions, and improves the polishing efficiency of the reducer elbow surface;

[0031] 3. The present invention drives different pistons to reciprocate regularly through a controller, thereby changing the pressure in the working chamber and generating negative pressure to achieve cavitation. When the volume of the closed working chamber increases, the liquid pressure drops to the saturated vapor pressure, thereby achieving cavitation initiation and generating cavitation bubbles; when the piston is squeezed, the pressure in the closed working chamber increases, causing the cavitation bubble collapse. The regular reciprocating motion of the piston realizes the cycle of cavitation initiation, development, and collapse in the working chamber. When the pressure on the upper surface of the inner wall of the reducer elbow reaches the pressure of cavitation collapse, the cavitation collapses and releases huge energy. The water flow, abrasive flow, and high-energy released by the collapse of cavitation bubbles are used to fill the microscopic pits on the inner surface of the elbow and remove tiny defects. The elbow can be further strengthened after initial polishing to achieve integrated polishing and strengthening.

[0032] 4. The present invention utilizes the high concentrated energy and impact generated by the collapse of cavitation bubbles in the cavitation effect to process the inner surface of the reducer elbow, and further polishes the inner surface. Compared with traditional polishing, better surface quality and lower surface roughness can be obtained. At the same time, the abrasive flow is difficult to empty at one time. Under the force generated by the collapse of cavitation bubbles, the abrasive flow impacts and strengthens the inner surface of the elbow, and hits the inner surface at a higher speed and kinetic energy, so that the cavitation effect and the abrasive flow polishing work together to further enhance the microscopic strengthening effect of the surface. It can further reduce possible harmful deformations such as microcracks and improve the comprehensive performance of the reducer elbow. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is the overall system diagram of the present invention;

[0034] Figure 2 It is an enlarged view of the cavity, the die and the connection of the variable diameter elbow to be processed;

[0035] Figure 3 It is the structural diagram of the mold;

[0036] Figure 4 yes Figure 1 Diagram of the piston and valve structure inside the piston cylinder during internal polishing;

[0037] Figure 5 yes Figure 1 The piston and valve structure diagram inside the piston cylinder when the abrasive flow is discharged after the polishing work is completed;

[0038] Figure 6 yes Figure 1 The structure diagram of the piston and valve inside the piston cylinder when the device is in the initial state of surface strengthening work;

[0039] Figure 7 yes Figure 1 The diagram shows the structure of the piston and valve inside the piston cylinder when the device is in the intermediate state of surface strengthening work.

[0040] In the figure: 1. Piston 1; 2. Piston 2; 3. Piston 3; 4. Valve 1; 5. Valve 2; 6. Water inlet; 7. Abrasive inlet; 8. Flange 1; 9. Flange 2; 10. Mould; 11. Reducer elbow; 12. Flange 3; 13. Flange 4; 14. Valve 3; 15. Water outlet; 16. Abrasive outlet; 17. Valve 4; 18. Piston 4; 19. Piston 5; 20. Piston 6; 21. Flange 5; 22-1. Left piston cylinder; 22-2. Right piston cylinder; 23. Water flow; 24. Abrasive flow; 25. Cavitation; 26. Maximum stroke of piston 1; 27. Minimum stroke of piston 1; 28. Minimum stroke of piston 2; 29. ​​Maximum stroke of piston 2; 30. Minimum stroke of piston 6; 31. Maximum stroke of piston 6; 32. Maximum stroke of piston 4; 33. Minimum stroke of piston 4. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] See also Figures 1 to 5The present invention provides a technical solution: a device for polishing and strengthening the inner surface of a variable diameter elbow, comprising a variable diameter elbow 11 and piston cylinders located at both ends of the variable diameter elbow 11, wherein the piston cylinders are divided into a left piston cylinder 22-1 and a right piston cylinder 22-2, wherein the left piston cylinder 22-1 is larger than the right piston cylinder 22-2, wherein the end of the variable diameter elbow 11 with a larger radial cross-sectional area is an inlet end connected to the left piston cylinder 22-1, and the end of the variable diameter elbow 11 with a smaller radial cross-sectional area is an outlet end connected to the right piston cylinder 22-2.

[0043] In this embodiment, piston 1, piston 2, and piston 3 are provided in the left piston cylinder 22-1. Piston 1 is arranged alone in the left piston cylinder 22-1, and piston 2, piston 3, and piston 3 are relatively arranged in the left piston cylinder 22-1. The left piston cylinder 22-1 is also provided with a water inlet 6 and an abrasive inlet 7. The central axes of piston 1 and flange 1 are collinear, the axial length of piston 1 is greater than the axial lengths of piston 2 and piston 3, the size of piston 1 is greater than piston 2 and piston 3, piston 2 and piston 3 have the same structure, are located on both sides perpendicular to the axis of piston 1, and are symmetrically arranged relative to the central axis of piston 1.

[0044] In this embodiment, the right piston cylinder 22-2 is provided with a piston four 18, a piston five 19 and a piston six 20, and the piston six 20 is separately arranged in the right piston cylinder 22-2. The piston four 18 and the piston five 19 are relatively arranged in the right piston cylinder 22-2. The right piston cylinder 22-2 is also provided with a water outlet 15 and an abrasive outlet 16. The right piston cylinder 22-2 and the left piston cylinder 22-1 have the same structure and only differ in size.

[0045] In this embodiment, a mold 10 is provided in the reducer bend 11, and the shape of the mold 10 is contoured according to the shape of the reducer bend 11. The width of the interval between the inner wall of the reducer bend 11 and the outer wall of the mold 10 increases as the inner wall diameter of the reducer bend 11 decreases.

[0046] In this embodiment, a valve 1 4 is provided in the water inlet 6 , and a valve 2 5 is provided in the abrasive inlet 7 .

[0047] In this embodiment, the left piston cylinder 22-1 is fixedly connected to the flange 2 9 on the reducer bend 11 via the flange 1 8, a sealing flange 5 21 is provided between the flange 1 8 and the flange 2 9, and the right piston cylinder 22-2 is fixedly connected to the flange 3 12 on the reducer bend 11 via the flange 4 13.

[0048] In this embodiment, taking the left piston cylinder 22-1 as an example, when the reducing elbow 11 is fixed and the valve 1 4 and the valve 2 5 are closed, the piston 1 1, the piston 2 2 and the piston 3 3 enclose the piston cylinder to form a closed working chamber. Each piston is tightly sealed with the inner wall of the corresponding through hole and can reciprocate along the inner wall of the through hole, approaching or moving away from the working chamber, and finally realizing the reduction or increase of the volume of the working chamber.

[0049] In this embodiment, piston 1 can be extended into the working chamber, the maximum stroke 26 is located between the water inlet 6 and the abrasive inlet 7, the minimum stroke 27 is located in the working chamber, piston 2 2 and piston 3 3 have the same stroke, such as the maximum stroke 29 of piston 2 2 does not exceed the maximum position of the through hole where it is located, and cannot be extended into the working chamber, and the minimum stroke 28 of piston 2 2 is in the copper tube.

[0050] In this embodiment, the three pistons and two valves of the left piston cylinder 22-1 and the right piston cylinder 22-2 are independently driven by an external controller (the controller is omitted in the figure), and the controller independently drives the three pistons to move and the two valves to open and close.

[0051] In this embodiment, the piston moves under the drive of the controller to reduce or increase the volume of the working chamber. Taking the left piston cylinder 22-1 as an example, when the piston 1 moves to the maximum stroke 26, it can extend into the working chamber to reduce the volume of the working chamber. When the piston 1 moves to the minimum stroke 27, the volume of the working chamber is increased. By changing the volume of the working chamber, the purpose of changing the pressure in the working chamber is achieved.

[0052] In this embodiment, a valve three 14 is provided in the water outlet 15 , and a valve four 17 is provided in the abrasive outlet 16 .

[0053] In this embodiment, the flange plate 5 21 is fixedly connected to the root of the mold 10 , and a through hole is provided on the flange plate 5 21 .

[0054] In this embodiment, the reducer elbow 11 is tightly fitted with the piston cylinder and the mold 10, and the outlet flange 18 of the left piston cylinder 22-1 is fixedly connected to the flange 29 of the reducer elbow 11 and the flange 5 21 of the mold by bolts. A sealing rubber ring 1 is installed between the flange 18 and the flange 5 21, and a sealing rubber ring 2 is installed between the flange 5 21 and the flange 2 9. The inner diameters of the sealing rubber ring 1, the sealing rubber ring 2 and the flange 18, the flange 29 and the flange 5 21 are consistent. Similarly, a sealing rubber ring 3 is installed between the flange 4 13 of the inlet section of the right piston cylinder 22-2 and the flange 3 12 of the reducer elbow 11, and the inner diameter of the sealing rubber ring 3 is consistent with the flange 3 13 and the flange 4 12. When the reducer elbow 11, the mold 10 and the left piston cylinder 22-1 and the right piston cylinder 22-2 are fixed by the flange, the left piston cylinder 22-1, the right piston cylinder 22-2 and the reducer elbow 11 are connected to each other through the sealing rubber ring 1, the sealing rubber ring 2 and the sealing rubber ring 3 to form a closed sealed space.

[0055] In this embodiment, the inner diameter of flange five 21 processed at the end of the mold 11 is the same as flange one 8 and flange two 9. Four brackets are processed at equal angles on the inner diameter of flange five 21 and are welded to fix the mold 10.

[0056] In this embodiment, the axial end face lengths of the flange 5 21 and the mold 10 are equal, the mold 10 is installed at the inner diameter axis of the flange 5 21, and the mold 10 is specially processed to ensure that any radial cross-sectional area between the reducer 11 and the mold 10 increases as the inner wall diameter of the reducer 11 decreases, so that the abrasive flow 24 has the same speed and pressure when passing through the reducer, and the same force is applied to its inner surface.

[0057] Working principle: First, the left piston cylinder 22-1, the right piston cylinder 22-2, the reducer elbow 11 and the mold 10 are fixedly connected and assembled.

[0058] like Figure 4 As shown, after the assembly is completed, the inner surface polishing and strengthening device of the reducer elbow 11 starts to work. Piston 1 moves to the maximum stroke 26 under the drive of the controller, and piston 6 20 moves to the maximum stroke 31 under the drive of the controller. Valve 2 5 of the abrasive inlet 7 and valve 3 14 of the abrasive outlet 16 are opened, and the abrasive flow 24 enters the space between the reducer elbow 11 and the mold 10 through the abrasive inlet 7 under the action of high pressure for polishing, and finally is discharged from the abrasive outlet 16. In the polishing process, piston 1 and piston 6 20 are both located at the maximum stroke, which minimizes the volume of the working chamber, does not occupy the abrasive flow 24, and improves the polishing efficiency.

[0059] Since the mold 10 is manufactured separately according to different reducer elbows 11, it can be ensured that the arbitrary radial cross-sectional area between the reducer elbow and the mold increases as the inner wall diameter of the reducer elbow 11 decreases. The pressure distribution of the abrasive flow 24 inside the reducer elbow 11 tends to be consistent, avoiding the local accumulation of the abrasive flow 24 or the phenomenon of excessive flow rate, and achieving uniform polishing of the inner wall. And from fluid mechanics, it can be known that the speed and pressure values ​​of the abrasive flow 24 in the pipeline tend to be constant, avoiding the abrasive flow in a certain part of the pipeline to produce a large local stress concentration, resulting in uneven polishing or damage to the inner wall. By introducing a specifically processed mold, the uniformity and quality of the inner surface polishing are improved.

[0060] like Figure 5 As shown, after the inner wall of the reducer elbow 11 is polished, a large amount of abrasive flow 24 remains in the gap between the working chamber and the inner wall of the elbow, and the abrasive flow 24 discharge process is performed. Valve 2 5, valve 3 14 and valve 4 17 are closed to stop the injection and discharge of the abrasive flow, and piston 1 1 and piston 6 20 are driven by the controller to move to the minimum stroke, and piston 2 2, piston 3 3, piston 4 18 and piston 5 19 still perform relative reciprocating motion to improve the fluidity of the subsequently injected water flow and obtain a better abrasive flow 24 discharge effect.

[0061] Open valve 14 of water inlet 6, inject water flow 23 into the working chamber and the gap between the reducer elbow 11 and the mold 10, and after injecting an appropriate volume of liquid, piston 11 and piston 6 20 perform regular reciprocating motion under the drive of the controller. When piston 1 reaches the maximum stroke 26, piston 6 20 is at the minimum stroke 30. When piston 1 reaches the minimum stroke 27, piston 6 20 is at the maximum stroke 31, so that the abrasive flow 24 in the gap between the working chamber and the reducer elbow 11 and the mold 10 is mixed with the injected liquid. Finally, piston 1 and piston 6 20 stop moving, close valve 14, and open valve 4 17 of water outlet 15 to discharge the abrasive flow 24 and liquid.

[0062] like Figure 6 and Figure 7As shown, the abrasive flow added for polishing is difficult to be discharged at one time. At this time, with the help of the undischarged abrasive flow 24, the water flow 23 interacts with the inner wall of the elbow under the driving of the high-energy released by the collapse of the cavitation bubble 25, and the inner wall of the elbow is strengthened. Close the valve 4 17, control the piston 1 to the minimum stroke 27, and the remaining pistons move to the maximum stroke under the drive of the controller. Open the valve 14 of the water inlet pipeline, fill the working chamber and the gap between the variable diameter elbow 11 and the mold 10 with liquid, and then close the valve 14. Start the drivers of all pistons, all pistons move to the minimum stroke at the same time, and then move to the maximum stroke at the same time, and continue this regular reciprocating motion, so that the volume of the enclosed space changes repeatedly. When the enclosed space is stretched out synchronously, when the pressure drops below the saturated vapor pressure of the liquid, cavitation occurs, and cavitation bubbles 25 are precipitated from the liquid, and further develop and expand as the volume increases. When the volume of the enclosed space decreases and the internal pressure increases, the generated cavitation bubbles 25 collapse and collapse, thereby releasing high-energy, producing microscopic compression deformation, filling the microscopic pits on the surface and removing tiny defects, thereby achieving the effect of strengthening the inner wall of the elbow. The instantaneous shock wave generated by the collapse of the cavitation bubble 25 can not only directly act on the inner surface of the elbow, but also drive the abrasive flow 24 to impact the inner surface at a higher speed and kinetic energy, so that the cavitation effect and the polishing of the abrasive flow 24 work together to further enhance the microscopic strengthening effect of the surface.

[0063] Since the radial cross-sections of the reducer elbow 11 are different, in order to achieve a uniform surface strengthening effect, during installation, the inlet end of the reducer elbow 11 with a larger cross-sectional area is fixedly connected to the left piston cylinder 22-1, and the outlet end with a smaller radial cross-sectional area is fixedly connected to the right piston cylinder 22-2, and the size of the left piston cylinder 22-1 is larger than that of the right piston cylinder 22-2. The size of piston 1 is larger than that of piston 6 20, so when the volume changes, the cavitation group generated by the left piston cylinder 22-1 is more than that of the right piston cylinder 22-2. When the cavitation group enters the inner surface of the elbow under the push of the piston and collapses, the number of cavitations 25 at the inlet end of the elbow is greater than that at the outlet end, so the inlet end with a larger radial cross-sectional area is subjected to a greater force than the outlet end with a smaller cross-sectional area, avoiding uneven strengthening.

[0064] When the polishing and strengthening of the inner wall of the reducer elbow 11 reaches the desired effect, the driver stops and resets the piston, opens the valve 3 18 of the water outlet 15, releases the water flow 23 and the abrasive flow 24, loosens the bolts, removes the reducer elbow 11 and the mold 10, and completes the polishing.

[0065] A method for polishing and strengthening the inner surface of a variable diameter elbow comprises the following steps:

[0066] S1. The piston is driven by an external controller to move to a maximum piston stroke 26, between the water inlet 6 and the abrasive inlet 7, and the piston is driven to the maximum piston stroke 31 at 20, between the water outlet 15 and the abrasive outlet 16;

[0067] S2. Open the control valve 25 and valve 417 of the abrasive flow inlet 7 and the abrasive flow outlet 16 pipelines. Under the action of the external supply device, the abrasive flow 24 enters the working chamber of the left piston cylinder 22-1 from the abrasive flow inlet 7 and enters the gap between the reducer elbow 11 and the mold 10. During the flow of the abrasive flow 24, the inner surface of the reducer elbow 11 is polished. Finally, the excess abrasive flow 24 is discharged through the abrasive flow outlet 16 under the action of pressure.

[0068] S3. Close the abrasive flow inlet 7 and the abrasive flow outlet 16 of the pipeline control valve 2 5, valve 4 17, stop the abrasive flow 24 filling;

[0069] S4. Drive the piston through an external controller to a displacement of the minimum stroke 27, open the water inlet pipe control valve 6 - 4 to the left piston cylinder 22-1 working chamber water flow 23;

[0070] S5. At this time, piston 1 is located at the minimum stroke 27, and piston 6 20 is located at the minimum stroke 30, so that the working chamber volume of the left piston cylinder 22-1 and the right piston cylinder 22-2 is as large as possible. After injecting an appropriate volume of internal water flow 23, the piston 1 and piston 6 20 reciprocate in the same direction and frequency. When piston 1 is compressed to the minimum stroke 27, piston 6 20 is stretched to the maximum stroke 31 at the same time. When piston 1 is stretched to the maximum stroke 26, piston 6 20 is compressed to the minimum stroke 30 at the same time. In the left piston cylinder 22-1, piston 2 and piston 3 reciprocate in the same direction and frequency. In the right piston cylinder 22-2, piston 4 18 and piston 5 19 reciprocate in the same direction and frequency, so that the internal water flow 23 and the abrasive flow 24 are evenly mixed.

[0071] S6. After opening the abrasive outlet 16 pipe control valve 17, discharge part of the mixed liquid;

[0072] S7. The control piston 1 is located at the minimum stroke 27, and the remaining pistons are located at the maximum stroke. Open the water inlet pipe control valve 6-4, fill the water flow 23 and close all valves;

[0073] S8. Control piston 6 20 to move to the minimum stroke 30, control piston 2 2, piston 3 3, piston 4 18, piston 5 19 to move synchronously to the minimum stroke, and reduce the pressure in the working chamber of the left piston cylinder 22-1, the right piston cylinder 22-2 and the reducer elbow 11 to below the saturated vapor pressure, thereby generating cavitation bubbles 25 through cavitation;

[0074] S9. After piston 1 reaches the minimum stroke 27 and piston 6 reaches the minimum stroke 30, all pistons are controlled to move toward the maximum stroke again. At this time, the pressure rises to collapse the cavitation bubble 25 and release energy, so that the abrasive flow 24 and the water flow 23 interact with each other to strengthen the inner surface;

[0075] S10. Control all pistons to repeat the above movement, and generate cavitation 25 during the compression movement of the piston to the minimum stroke, and collapse the cavitation 25 during the stretching movement of the piston to the maximum stroke, thereby strengthening the inner surface;

[0076] S11. Then open the control valve 4 17 of the abrasive outlet 16 pipeline, and the piston 1 1 and the piston 6 20 reciprocate in the same direction and frequency under control to discharge the mixed liquid, complete the strengthening, and remove the reducer.

[0077] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A device for polishing and strengthening the inner surface of a variable diameter elbow, characterized in that: It comprises a reducing elbow (11) and piston cylinders located at both ends of the reducing elbow (11), wherein the piston cylinder is divided into a left piston cylinder (22-1) and a right piston cylinder (22-2); The left piston cylinder (22-1) is provided with a piston one (1), a piston two (2), and a piston three (3); the piston one (1) is arranged alone in the left piston cylinder (22-1); the piston two (2) and the piston three (3) are arranged relatively in the left piston cylinder (22-1); and the left piston cylinder (22-1) is also provided with a water inlet (6) and an abrasive inlet (7); The right piston cylinder (22-2) is provided with a piston four (18), a piston five (19) and a piston six (20), the piston six (20) is arranged alone in the right piston cylinder (22-2), the piston four (18) and the piston five (19) are arranged relatively in the right piston cylinder (22-2), and the right piston cylinder (22-2) is also provided with a water flow outlet (15) and an abrasive flow outlet (16); A mold (10) is provided inside the reducer bend (11), the shape of the mold (10) is processed according to the shape of the reducer bend (11), and the width of the interval between the inner wall of the reducer bend (11) and the outer wall of the mold (10) increases as the inner diameter of the reducer bend (11) gradually decreases.

2. The device for polishing and strengthening the inner surface of a variable diameter elbow according to claim 1, characterized in that: The water inlet (6) is provided with a valve one (4), and the abrasive inlet (7) is provided with a valve two (5).

3. The device for polishing and strengthening the inner surface of a variable diameter elbow according to claim 1, characterized in that: The left piston cylinder (22-1) is fixedly connected to the flange plate 2 (9) on the reducer elbow (11) via the flange plate 1 (8), and a flange plate 5 (21) for sealing is provided between the flange plate 1 (8) and the flange plate 2 (9).

4. The device for polishing and strengthening the inner surface of a variable diameter elbow according to claim 1, characterized in that: The right piston cylinder (22-2) is fixedly connected to the flange plate three (12) on the reducer elbow (11) via the flange plate four (13).

5. The device for polishing and strengthening the inner surface of a variable diameter elbow according to claim 1, characterized in that: The water outlet (15) is provided with a valve three (14), and the abrasive outlet (16) is provided with a valve four (17).

6. The device for polishing and strengthening the inner surface of a variable diameter elbow according to claim 3, characterized in that: The flange plate five (21) is fixedly connected to the root of the mold (10), and a through hole is arranged on the flange plate five (21).

7. The method for polishing and strengthening the processing device according to claims 1-6, characterized in that: The following steps are involved: S1. The external controller drives piston 1 (1) to move to the maximum stroke of piston 1 (26), which is between the water inlet (6) and the abrasive inlet (7), and drives piston 6 (20) to the maximum stroke of piston 6 (31), which is between the water outlet (15) and the abrasive outlet (16); S2. Open the control valve 2 (5) and valve 4 (17) of the abrasive flow inlet (7) and the abrasive flow outlet (16) pipelines. Under the action of the external supply device, the abrasive flow (24) enters the working chamber of the left piston cylinder (22-1) from the abrasive flow inlet (7) and enters the gap between the reducer elbow (11) and the mold (10). During the flow of the abrasive flow (24), the inner surface of the reducer elbow (11) is polished. Finally, under the action of pressure, the excess abrasive flow (24) is discharged through the abrasive flow outlet (16); S3. Close the control valves 2 (5) and 4 (17) of the abrasive flow inlet (7) and the abrasive flow outlet (16) pipelines to stop the filling of the abrasive flow (24); S4. The piston (1) is driven by an external controller to move to the minimum stroke (27), and the control valve (4) of the water inlet (6) pipeline is opened to inject water into the working chamber of the left piston cylinder (22-1) (23); S5. At this time, the piston 1 (1) is located at the minimum stroke (27), and the piston 6 (20) is located at the minimum stroke (30), so that the working chamber volume of the left piston cylinder (22-1) and the right piston cylinder (22-2) is as large as possible. After injecting an appropriate volume of internal water flow (23), the piston 1 (1) and the piston 6 (20) reciprocate in the same direction and frequency. When the piston 1 (1) is compressed to the minimum stroke (27), the piston 6 (20) is stretched to the maximum stroke (31) at the same time. When the piston 1 (1) is stretched to the maximum stroke (26), the piston 6 (20) is compressed to the minimum stroke (30) at the same time. The piston 2 (2) and the piston 3 (3) in the left piston cylinder (22-1) reciprocate in the same direction and frequency. The piston 4 (18) and the piston 5 (19) in the right piston cylinder (22-2) reciprocate in the same direction and frequency, so that the internal water flow (23) and the abrasive flow (24) are evenly mixed. S6. Then open the control valve (17) of the abrasive outlet (16) pipeline to discharge part of the mixed liquid; S7. The control piston (1) is at the minimum stroke (27), and the remaining pistons are at the maximum stroke. Open the control valve (4) of the water inlet (6) pipeline, fill with water (23) and close all valves; S8. Control piston six (20) to move toward the minimum stroke (30), control piston two (2), piston three (3), piston four (18), and piston five (19) to move toward the minimum stroke synchronously, and reduce the pressure in the working chamber of the left piston cylinder (22-1), the right piston cylinder (22-2) and the reducer elbow (11) to below the saturated vapor pressure, thereby generating cavitation bubbles (25) through cavitation; S9. After piston one (1) reaches the minimum stroke (27) and piston six (20) reaches the minimum stroke (30), all pistons are controlled to move toward the maximum stroke again. At this time, the pressure rises to collapse the cavitation bubble (25) and release energy, so that the abrasive flow (24) and the water flow (23) interact with each other to strengthen the inner surface; S10. Control all pistons to repeat the above movement, generate cavitation bubbles (25) during the piston compression movement to the minimum stroke, and collapse cavitation bubbles (25) during the piston extension movement to the maximum stroke, thereby strengthening the inner surface; S11. Then, the control valve 4 (17) of the abrasive outlet (16) pipeline is opened, and the piston 1 (1) and the piston 6 (20) reciprocate in the same direction and frequency under control to discharge the mixed liquid, completing the strengthening, and removing the reducer elbow.

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