Device for polishing the inner surface of a curved pipe based on magnetic force grinding

Abstract

This invention discloses a polishing device for the inner surface of curved pipes based on magnetic abrasion, comprising a permanent magnet assembly, a movable base, a track assembly, and a control assembly. The track assembly is connected to the control assembly via a traction steel wire rope. The control assembly drives the movable base to reciprocate along the axial direction of the curved pipe workpiece. The permanent magnet assembly includes a large gear and a small gear connected by a transmission connection, with the small gear driven to rotate by a first drive motor. Multiple multi-layered neodymium iron boron permanent magnets are uniformly arranged circumferentially on the inner side of the large gear. The track assembly includes a deformable polyurethane rubber track, the shape of which is the same as that of the curved pipe workpiece. The movable base slides against the polyurethane rubber track via a bearing at its bottom. The traction steel wire rope passes through a connecting block at the bottom of the movable base and is connected to a wire drum at the output end of the track drive motor. Baffles are provided on both sides of the connecting block, and the baffles are fixed to the traction steel wire rope. This invention can efficiently polish the inner surface of stationary curved pipes of different shapes.

Description

Technical Field

[0001] This invention relates to the field of surface finishing technology for complex curved pipes, specifically to a polishing device for the inner surface of curved pipes based on magnetic abrasion. Background Technology

[0002] Magnetic abrasive finishing (MAF) is an advanced process that uses magnetic fields to drive tiny magnetic abrasive particles (grinding particles) to precisely polish, deburr, and round corners of workpiece surfaces. The magnetic abrasive particles are attracted by an external magnetic field and adhere to the inner or outer surface of the workpiece. The external magnetic field or the rotation of the workpiece then forms a magnetic brush, polishing both the inner and outer surfaces. MAF technology has become increasingly popular in recent years for precision surface finishing of materials. Compared to traditional precision machining methods, it offers advantages such as good self-adaptability and self-sharpening, and eliminates the need for tool compensation during processing. It has been widely applied in areas such as the inner surface of pipes, complex curved surfaces, and the surface finishing of tiny parts.

[0003] Currently, magnetic polishing devices mainly use machine tool fixtures to drive the workpiece to rotate, and use an external magnetic field to tightly attract the magnetic abrasive inside the workpiece to the inner surface of the workpiece, forming a magnetic brush. However, such devices are generally large in size, and since the machine tool drives the workpiece itself to rotate, they are only suitable for some straight workpieces. They cannot perform rotary polishing on non-rotating bodies such as curved workpieces.

[0004] Some devices are complex and large in size. For example, patent CN108972160A discloses a magnetic particle polishing device for the inner and outer surfaces of complex axial bends. Although this device can polish the inner surface of workpieces with complex axes, such as bends, it is large in size and complex to operate, making it difficult to achieve mass production polishing. Due to the complex shape and varying lengths of spatial bends, the processing of their inner and outer surfaces is extremely difficult. Burrs on the inner and outer surfaces of the bends are difficult to remove, and the surface finish is not high, making it difficult to guarantee the processing accuracy and surface quality of spatial bends. CN206632769 describes a polishing device for the inner surface of U-shaped tubes. Although this device is very effective in polishing slender straight tubes, the polishing head for the inner and outer surfaces of the bends, mounted on the spindle of a CNC machine tool, cannot move the axis of the spatial bend, thus making it unable to polish complex spatial bends. CN205734183 U discloses a handheld polishing machine for the inner surface of a bent pipe based on magnetic abrasion. However, compared with a handheld polishing device, polishing requires manual movement along the axis of a complex bent pipe, which is complicated and cumbersome, requires high skill from the operator, and results in low processing uniformity, which is not conducive to production automation. Therefore, it is difficult to complete the grinding and polishing of the inner and outer surfaces of a spatial bent pipe. Summary of the Invention

[0005] This invention provides a polishing device for the inner surface of curved pipes based on magnetic abrasion, used for polishing the inner surface of curved pipe workpieces of different shapes. The invention designs a deformable polyurethane rubber track that can fit the shape of the curved pipe workpiece. While keeping the curved pipe workpiece stationary, the permanent magnet assembly is controlled to move back and forth along the axial direction of the workpiece. Simultaneously, the rotation of the permanent magnet causes the magnetic abrasive inside the curved pipe workpiece to rotate circumferentially and reciprocate axially, thereby achieving the polishing of the inner surface of the curved pipe.

[0006] The technical solution of the present invention is as follows:

[0007] A polishing device for the inner surface of a curved pipe based on magnetic abrasion is described. The device includes a permanent magnet assembly mounted on a movable base connected to a track assembly. The track assembly is connected to a control assembly via a traction steel wire rope. The control assembly drives the movable base to reciprocate along the axial direction of the curved pipe workpiece via the traction steel wire rope. The permanent magnet assembly includes a large gear and a small gear connected by a transmission mechanism. The small gear is driven to rotate by a first drive motor. Multiple multi-layered neodymium iron boron permanent magnets are uniformly arranged circumferentially on the inner side of the large gear. The track assembly includes a deformable polyurethane rubber track with the same shape as the curved pipe workpiece. The movable base slides against the polyurethane rubber track via a bearing at its bottom. The traction steel wire rope passes through a connecting block at the bottom of the movable base and connects to a wire drum at the output end of the track drive motor. Baffles are provided on both sides of the connecting block and are fixed to the traction steel wire rope.

[0008] Compared with the prior art, the present invention solves the problem of "difficult polishing of curved pipes" and the motion mechanism operates stably. Compared with the method of polishing by moving the workpiece, the present invention has higher polishing efficiency and lower polishing cost. Specifically, the present invention has achieved the following significant progress: (1) The present invention uses a deformable polyurethane rubber track, which can be twisted to change its shape, so as to be suitable for curved pipes of various shapes, and has strong universal applicability; (2) The present invention sets up multiple multi-layer neodymium iron boron permanent magnet structures, and by increasing or decreasing the number of layers of neodymium iron boron permanent magnets, it can be suitable for curved pipes of different diameters, further improving the universal applicability of the present invention. Moreover, the process parameters of the magnetic force can be adjusted by changing the distance between the neodymium iron boron permanent magnet and the outer wall of the curved pipe workpiece; (3) The present invention uses a specific motion mechanism, with large gear, small gear, moving base, traction steel wire rope, control components, etc. working together to achieve stable operation. Moreover, when the curved pipe workpiece is stationary, the magnetic abrasive can be rotated along the circumference of the pipe inside the curved pipe workpiece, and reciprocate along the axial direction of the pipe, so as to achieve polishing of the inner wall of the curved pipe workpiece.

[0009] Preferably, in the aforementioned magnetic abrasion-based polishing device for the inner surface of bent pipes, multiple galvanized iron wires are embedded on both sides of the polyurethane rubber track. After the polyurethane rubber track is deformed according to the shape of the bent pipe workpiece, the galvanized iron wires can shape the bent polyurethane rubber track, making the shape of the polyurethane rubber track more stable.

[0010] Preferably, in the aforementioned magnetic abrasion-based polishing device for the inner surface of curved pipes, the small gear is connected to a movable base via a bracket; baffles are provided on both sides of the large gear. The bracket improves the stability of the large and small gears when they rotate relative to each other, and the baffles prevent misalignment when they rotate relative to each other; both together improve the stability of the polishing process.

[0011] Preferably, in the aforementioned magnetic abrasion-based polishing apparatus for the inner surface of curved pipes, the curved pipe workpiece is fixed to the polishing apparatus by a three-jaw chuck. The three-jaw chuck has good fixing performance, which can prevent the curved pipe workpiece from shaking or shifting, thereby improving the polishing quality.

[0012] Preferably, in the aforementioned magnetic abrasion-based polishing device for the inner surface of curved pipes, the control component includes a pressure sensor. This pressure sensor transmits a contact signal from the movable base to a control box, which then controls the start / stop or forward / reverse rotation of the track drive motor based on the contact signal. Using a pressure sensor to transmit signals and control the start / stop or forward / reverse rotation of the track drive motor simplifies the control structure and reduces the production cost of the device.

[0013] Preferably, in the aforementioned magnetic abrasive-based polishing device for the inner surface of a curved pipe, the curved pipe workpiece is U-shaped, and there are two track drive motors, including a first track drive motor and a second track drive motor, which are respectively located at both ends of the U-shaped curved pipe workpiece. The control component includes two pressure sensors, which are respectively located at both ends of the U-shaped curved pipe workpiece. The pressure sensors can transmit the contact signal of the moving base to the control box, and the control box controls the start, stop, or forward and reverse rotation of the two track drive motors according to the contact signal.

[0014] Preferably, in the aforementioned magnetic abrasive-based polishing device for the inner surface of curved pipes, 2-6 layers of neodymium iron boron permanent magnets are uniformly arranged circumferentially on the inner side of the large gear. This invention can use multiple layers of neodymium iron boron permanent magnets depending on the diameter of the curved pipe workpiece. Using 2-6 layers of neodymium iron boron permanent magnets can meet the needs of most applications, and this arrangement results in high polishing efficiency and precision. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the magnetic abrasive-based polishing device for the inner surface of a curved pipe according to the present invention.

[0016] Figure 2 This is an enlarged schematic diagram of a partial structure of the present invention.

[0017] Figure 3 This is a schematic diagram of the present invention with some parts omitted.

[0018] Figure 4 This is a bottom view of the present invention with some parts omitted.

[0019] Figure 5 This is the present invention. Figure 4 Enlarged schematic diagram of part A in the middle.

[0020] The labels in the attached diagram are as follows: 1-Bent pipe workpiece; 2-Permanent magnet assembly; 21-NdFeB permanent magnet; 22-Large gear; 23-Small gear; 24-First drive motor; 25-Baffle; 26-Bracket; 3-Three-jaw chuck; 4-Moving base; 41-Bearing; 42-Connecting block; 43-Baffle; 5-Rail assembly; 51-Traction steel wire rope; 52-Galvanized iron wire; 53-Polyurethane rubber track; 6-Control assembly; 61-First track drive motor; 62-First steel wire drum; 63-First pressure sensor; 64-Control box; 65-Second track drive motor; 66-Second steel wire drum; 67-Second pressure sensor. Detailed Implementation

[0021] The technical solution of the present invention will be further described in detail below through specific embodiments and with reference to the accompanying drawings, but this should not be construed as limiting the present invention. Contents not described in detail in the following embodiments are all common knowledge in the art or can be implemented using conventional technical means in the art.

[0022] Reference to embodiments of the present invention Figures 1-5 This embodiment uses a U-shaped curved pipe as an example to specifically illustrate the polishing device of the present invention.

[0023] like Figure 1As shown, the two ends of the U-shaped curved pipe workpiece 1 are fixedly connected to the polishing device via three-jaw chucks 3. The polishing device includes a track assembly 5 that matches the shape of the U-shaped curved pipe workpiece 1. The track assembly 5 is a deformable structure that can be twisted into a matching shape according to the shape of the curved pipe workpiece 1. For example, when polishing an S-shaped curved pipe workpiece 1, the track assembly 5 can be twisted into an "S" shape to match the curved pipe workpiece 1. The track assembly 5 includes a traction steel wire rope 51 and a polyurethane rubber track 51, which is made entirely of polyurethane rubber material. Three galvanized iron wires 52 with a diameter of 2mm are embedded on both sides of the polyurethane rubber track 51. The polyurethane rubber material has good elasticity and can be bent, and the galvanized iron wires 52 can shape the polyurethane rubber track 51 after bending. Therefore, the polyurethane rubber track 51 can be adjusted according to the different shapes of the curved pipe workpiece 1, making it widely applicable.

[0024] The polishing device also includes a movable base 4, which is connected to a traction steel wire rope 51 via a connecting block 42 at the bottom, and the traction steel wire rope 51 passes through a hole in the connecting block 42.

[0025] A baffle 43 is provided on each side of the connecting block 42. The baffle 43 is sleeved on the traction steel wire rope 51 and fixedly connected to the traction steel wire rope 51. Bearings 41 are also provided at the four corners of the bottom of the movable base 4. The bearings 41 are slidably engaged with the polyurethane rubber track 51. When the traction steel wire rope 51 is pulled, the movable base 4 moves along the polyurethane rubber track 51 through the baffles 43 and the bearings 41.

[0026] The movable base 4 is controlled by a control component 6. The control component 6 includes a control box 64 and a first track drive motor 61, a second track drive motor 65, a first pressure sensor 63, and a second pressure sensor 67 connected to the control box 64. The two track drive motors and two pressure sensors are respectively located at the two ends of the U-shaped polyurethane rubber track 51. The first pressure sensor 63 and the second pressure sensor 67 correspond to the extreme positions of the movable base 4's movable range. The first track drive motor 61 is connected to a first wire drum 62 via an output shaft, and one end of the traction wire rope 51 is wound around the first wire drum 62. The second track drive motor 65 is connected to a second wire drum 66 via an output shaft, and the other end of the traction wire rope 51 is wound around the second wire drum 66. During operation, the second track drive motor 65 is turned off, and the control box 64 controls the first track drive motor 61 to start, driving the first wire drum 62 to rotate. This causes the traction wire rope 51 to move the movable base 4 along the U-shaped polyurethane rubber track 51 from one end to the other. When the movable base 4 moves to the other end of the polyurethane rubber track 51 and touches the second pressure sensor 67, the second pressure sensor 67 transmits a signal to the control box 64. The control box 64 then controls the first track drive motor 61 to stop and controls the second track drive motor 65 to start. The second track drive motor 65 drives the second wire drum 66 to rotate, causing the traction wire rope 51 to move the movable base 4 along the U-shaped polyurethane rubber track 51 in the opposite direction. When the movable base 4 moves to the other end of the polyurethane rubber track 51 and touches the first pressure sensor 63, the control box 64 again controls the start / stop or forward / reverse rotation of the two motors to achieve the back-and-forth movement of the movable base 4 along the U-shaped polyurethane rubber track 51.

[0027] A permanent magnet assembly 2 is installed on the upper part of the movable base 4. The permanent magnet assembly 2 includes a large gear 22 and a small gear 23, which are connected by a transmission. The small gear 23 is fixed above the movable base 4 by a bracket 26. The small gear 23 is driven to rotate by a first drive motor 24. Multiple multi-layered fan-shaped neodymium iron boron permanent magnets 21 are arranged circumferentially on the inner side of the wheel body of the large gear 22. The multiple layers of neodymium iron boron permanent magnets 21 are connected by magnetic attraction. By disassembling or adding, the permanent magnet assembly 2 can be adapted to curved pipe workpieces 1 of various pipe diameters. In this embodiment, a structure with three layers and a total of 12 neodymium iron boron permanent magnets 21 is shown. Baffles 25 are respectively provided on both sides of the large gear 22 along the axial direction. The baffle structure can prevent the large gear 22 and the small gear 23 from misaligning during the movement of the movable base 4, which would cause the large gear 22 to fall off.

[0028] The polishing process of the U-shaped curved pipe workpiece 1 of this invention is as follows: An appropriate amount of magnetic abrasive is placed inside the U-shaped curved pipe workpiece 1. Both ends of the curved pipe workpiece 1 are connected to the polishing device via a three-jaw chuck 3. An appropriate number of neodymium iron boron permanent magnets 21 are placed according to the pipe diameter of the curved pipe workpiece 1. The first drive motor 24 is started, causing the pinion 23 to drive the large gear 22 to rotate. The control box 64 alternately drives the first track drive motor 61 and the second track drive motor 65 to rotate in opposite directions, causing the moving base 4 to carry the permanent magnet assembly 2 and reciprocate along the axial direction of the curved pipe workpiece 1. The magnetic abrasive reciprocates circumferentially and axially inside the curved pipe workpiece 1, ultimately achieving polishing of the inner surface of the curved pipe workpiece 1.

[0029] This invention takes a U-shaped steel pipe with a length of 50cm, a bending radius of 10cm, and a cross-sectional diameter of 5cm as an example for specific explanation:

[0030] The magnetic abrasive used in this embodiment is an iron-based white corundum magnetic abrasive prepared by sintering, with a ferromagnetic phase (Fe) to abrasive phase (Al2O3) mass ratio of 4:1. The phases include Fe, Al2O3, and Fe2O3. The abrasive particle size is 80 mesh. The unfolded length of the U-shaped steel tube used is 50 cm, the inner diameter is 5 cm, and the internal volume is 981 mL. The amount of magnetic abrasive used is 130 g, which can form an annular magnetic brush on the inner wall of the tube.

[0031] The magnetic abrasive is loaded into the inner cavity of the U-shaped steel tube, and its two ends are fixed by the three-jaw chuck 3. The first drive motor 24 is started, and the motor speed is adjusted so that the rotation speed of the large gear 22 reaches 1000 r / min. The neodymium iron boron permanent magnet 21 attracts the magnetic abrasive on the inner wall of the U-shaped steel tube, causing the magnetic abrasive to rotate tightly against the inner wall of the U-shaped steel tube. The first track drive motor 61 is started, and the moving speed of the moving base 4 is set to 15 mm / s. The moving base 4 moves along the polyurethane rubber track 53 according to the set speed under the drive of the first track drive motor 61, so that the permanent magnet assembly 2 moves along the axial direction of the U-shaped steel tube. The magnetic abrasive moves along the axial direction while rotating circumferentially on the inner wall of the U-shaped steel tube, polishing the inner wall of the U-shaped steel tube.

[0032] When the movable base 4 moves to the other end of the U-shaped steel pipe, it triggers the pressure sensor. The pressure sensor transmits a contact signal to the control box 64, which then shuts off the first track drive motor 61 and starts the second track drive motor 65, causing the movable base 4 to move in the opposite direction. Thus, through the reciprocating movement of the movable base 4 and the rotation of the large gear 22, the inner wall of the U-shaped steel pipe is polished. After 40 minutes of polishing, the original milling marks on the inner surface of the U-shaped steel pipe are effectively removed, and the surface roughness Ra is reduced from the initial 1.32 μm to 0.24 μm. The surface is bright and uniform, without over-grinding or scratches. The magnetic abrasive does not show significant shedding after a single polishing cycle and can be reused.

[0033] The foregoing general description of the invention and its specific embodiments should not be construed as a limitation on the technical solution of the invention. Those skilled in the art, based on the disclosure of this application, can add, reduce, or combine the disclosed technical features in the foregoing general description and / or specific embodiments (including examples) without departing from the constituent elements of the invention, to form other technical solutions within the scope of protection of this invention.

Claims

1. A polishing device for the inner surface of a curved pipe based on magnetic abrasion, characterized in that: The polishing device includes a permanent magnet assembly (2), which is mounted on a movable base (4). The movable base (4) is connected to a track assembly (5), which is connected to a control assembly (6) via a traction wire rope (51). The control assembly (6) can drive the movable base (4) to reciprocate along the axial direction of the curved pipe workpiece (1) via the traction wire rope (51). The permanent magnet assembly (2) includes a large gear (22) and a small gear (23) connected by a transmission. The small gear (23) is driven to rotate by a first drive motor (24). The inner side of the large gear (22) is along... Multiple multilayer neodymium iron boron permanent magnets (21) are uniformly arranged in the circumferential direction; the track assembly (5) includes a deformable polyurethane rubber track (53), the shape of which is the same as that of the curved pipe workpiece (1); the movable base (4) slides with the polyurethane rubber track (53) through the bearing (41) at the bottom; the traction steel wire rope (51) passes through the connecting block (42) at the bottom of the movable base (4) and is connected to the steel wire drum at the output end of the track drive motor; baffles (43) are provided on both sides of the connecting block (42), and the baffles (43) are fixedly engaged with the traction steel wire rope (51).

2. The device for polishing the inner surface of a curved pipe based on magnetic abrasion according to claim 1, characterized in that: Multiple galvanized iron wires (52) are embedded in both sides of the polyurethane rubber track (53).

3. The device for polishing the inner surface of a curved pipe based on magnetic abrasion according to claim 1, characterized in that: The small gear (23) is connected to the movable base (4) via a bracket (26); baffles (25) are provided on both sides of the large gear (22).

4. The device for polishing the inner surface of a curved pipe based on magnetic abrasion according to claim 1, characterized in that: The curved pipe workpiece (1) is fixed on the polishing device by a three-jaw chuck (3).

5. The device for polishing the inner surface of a curved pipe based on magnetic abrasion according to claim 1, characterized in that: The control component (6) includes a pressure sensor that can transmit the contact signal of the movable base (4) to the control box (64), which controls the start and stop or forward and reverse rotation of the track drive motor according to the contact signal.

6. The magnetic abrasive-based polishing apparatus for the inner surface of curved pipes according to any one of claims 1-5, characterized in that: The curved pipe workpiece (1) is U-shaped, and there are two track drive motors, including a first track drive motor (61) and a second track drive motor (65), which are respectively located at both ends of the U-shaped curved pipe workpiece (1); the control component (6) includes two pressure sensors, which are respectively located at both ends of the U-shaped curved pipe workpiece (1); the pressure sensors can transmit the contact signal of the moving base (4) to the control box (64), and the control box (64) controls the start and stop or forward and reverse rotation of the two track drive motors according to the contact signal.

7. The magnetic abrasive-based polishing apparatus for the inner surface of curved pipes according to any one of claims 1-5, characterized in that: Three layers of neodymium iron boron permanent magnets (21) are uniformly arranged circumferentially on the inner side of the large gear (22).

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