Abrasive flow polishing device and method for polishing of inner surface of slender tubes

Abstract

An abrasive flow polishing device (and method) for polishing of an inner surface of slender tubes includes a workbench, fluid processing units and a magnetic control fluid unit. Two fluid processing units are symmetrically mounted on left and right sides of the workbench. The slender tube is connected to the fluid processing units. Left and right ends of a slender tube are connected to the fluid processing units on the left and right sides of the workbench. The magnetic control fluid unit is disposed below the workpiece, and controls magnetic particles in a polishing liquid through a magnetic field applied by a magnetic pole to form a magnetic chain with a certain yield strength in a direction of a magnetic force and form a local blocking block adsorbed on an inner surface of the workpiece to reduce an actual aperture for flowing the polishing liquid in the blocking area.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the field of abrasive flow precision processing, and relates to an abrasive flow polishing device and method for magnetic field-assisted abrasive flow polishing of an inner surface of slender tubes.BACKGROUND

[0002] Miniaturization trend of modern high-end precision devices makes slender tubular parts with small aperture sizes and large length-diameter ratios to be widely used in aerospace, biomedical engineering, chemical engineering and other fields to achieve sample extraction, fluid transportation, heat conduction and heat dissipation and the like. In order to ensure stability, accuracy and non-residue of sample extraction and fluid transportation, the inner surface of slender tubes need to have high smoothness. Currently, processes for preparing the slender tubular parts mainly include drawing forming and extrusion forming, which inevitably produce wrinkles on inner surfaces of small-aperture or variable-aperture tubes, resulting in that the inner surface roughness of the tubes do not meet industrial requirements and a further polishing is needed.

[0003] Currently, main methods for polishing the inner surface of slender tubes include mechanical polishing, abrasive flow polishing, magnetic grinding and electrolytic polishing. For the mechanical polishing, a tool head is used to probe into the inside of a slender tube, but it is difficult to probe into a slender tube with an aperture of 1 mm and below. For the abrasive flow polishing, a high-pressure and high-viscosity non-Newtonian fluid is used for polishing, but the on-way attenuation of pressure inside the slender tube is significantly, resulting in severe unevenness of polishing. For the magnetic grinding, a magnet is used to drive magnetic particles in the slender tube for polishing, but the magnetic particles cannot effectively and evenly cover the inner surface of the slender tube since a poor fluidity. For the electrolytic polishing, using a redox reaction, as an anode the slender tube is dissolved in an electrolyte solution, but it is difficult for a cathode to probe into the inside of the slender tube, which is prone to short circuit.

[0004] Patents of the prior art related to polishing of inner surface of slender tubes are as follows:

[0005] The Chinese patent application CN102211295A provides a device for magnetorheologically polishing inner wall of capillary tubes. The device uses a piston to inject magnetorheological fluid into the capillary tube, and simultaneously activates a vibration drive system to vibrate the capillary tube so as to improve fluidity of the magnetorheological fluid. After the capillary tube is completely filled with magnetorheological fluid, an electromagnet is started to generate a magnetic field to form a cylindrical polishing mold in the capillary tube, and the polishing mold rotates around the capillary tube and moves in an axial direction of the capillary tube to polish the inner surface of the capillary tube. Although the magnetic field and magnetorheological fluid are introduced for this device, using electromagnet to drive extremely small magnetic particles to grind walls of capillary tubes has an extremely low polishing efficiency.

[0006] The Chinese patent CN201455796U provides a device for polishing inner surface of steel pipes, which is capable of effectively polishing the inner surface of entire steel pipe. The device uses a polishing rope to polish the inner surface of steel pipe. The polishing rope penetrates through an inner hole of the steel pipe to be polished, and is wound round a driving wheel and a driven wheel, where the driving wheel is driven by a motor. A magnetic core is arranged in the polishing rope, and a magnetic strip capable of generating mutual attraction with the magnetic core is arranged below the steel pipe to be polished. Moreover, the motor drives the steel pipe to rotate, such that the inner surface of the steel pipe can be polished. The device has a simple structure and achieves a noticeable effect, but has high requirements for the polishing rope and limited polishing effect, which cannot meet polishing requirements for slender tubes requiring high internal surface quality. Further, the device has higher requirements for aperture sizes of slender tubes and is not suitable for polishing of slender tubes with smaller aperture sizes. Moreover, this method is not applicable to slender tubes with poor stiffness, and close fit between the polishing rope and the inner surface of slender tubes cannot be maintained.

[0007] The Chinese patent CN202137643U provides a device for magnetically polishing inner wall of slender tubes, which is capable of quickly deburring, polishing and cleaning inner walls of various metal tubes and non-metallic tubes made of hard plastic and the like. In this device, an iron core wrapped with coil is arranged below and on a side of a non-magnetic slender tube, a reciprocating alternating magnetic field is generated when AC current flows through the iron core, magnetic abrasive particles are placed into a tube cavity, the magnetic abrasive particles are driven by a magnetic field generated by the iron core, and at the same time, a motor drives the slender tube to rotate, such that an inner surface of the slender tube is polished. This device is capable of efficiently polishing inner surfaces that cannot be achieved or hardly achieved by means of traditional techniques, but the coils heat up severely when powered, and there are no corresponding cooling measures. Further, its transmission wheel is capable of transmitting only large-aperture tubes, which is unsuitable for processing of small-aperture slender tubes.

[0008] The Chinese patent application CN110815027A provides a device for polishing an inner hole of slender tubes, which has a simple structure and can be operated by one person alone. In the device, a flexible rod is used to connect a grinding head to an output end of a motor. The flexible rod is elastic, and one end of the flexible rod connected to the grinding head swings circumferentially relative to an axis of the flexible rod and when the motor rotates, such that an inner surface of the slender tube can be polished. Polished pipe fittings processed by the device have a high qualification rate, with low labor costs, high polishing efficiency and good polishing effects. However, the device is ineffective for some smaller-aperture slender tubes as the grinding head with a limited size cannot be inserted into the slender tubes.

[0009] The Chinese patent CN206998477U provides a device for polishing inner hole of slender tubes. The device performs axial polishing on the inner hole of slender tubes through yarn. The yarn is clamped and fixed sequentially through a guiding wheel, the inner hole of a slender tube and a roller, and the yarn drives abrasives to move relative to the inner hole of the slender tube in both axial and radial directions, such that the inner hole thereof can be polished. Although the yarn can enter a small inner hole, very little abrasive can be driven by the yarn, and a surface of the inner hole cannot be effectively polished.

[0010] Polishing tools of the above-mentioned patents and other devices for polishing inner surfaces of slender tubes are mostly polishing ropes and polishing rods, which cannot meet polishing requirements for small-aperture slender holes. Therefore, it is urgent to provide a device and method for polishing smaller-aperture slender holes, so as to ensure polishing efficiency and polishing accuracy.SUMMARY

[0011] In view of the defects of polishing solutions of the prior art, the present disclosure provides an abrasive flow polishing device and method for polishing of inner surface of slender tubes based on magnetic control of flow field scouring intensity. The present disclosure is capable of realizing rapid and uniform polishing of an inner surface of straight tube, variable-aperture tube or variable-roughness tube, which can reduce on-way resistance of a medium in the tube, improve sampling and injection accuracy, and enhance stability of fluid in the tube. The present disclosure solves problems of the prior art including limited, uneven and inefficient polishing of inner surfaces of slender tubes.

[0012] In order to realize the aforementioned objects, technical solutions adopted by the present invention are as follows:

[0013] A device for fluid polishing of inner surface of slender tubes includes a workbench, fluid processing units and a magnetic control fluid unit. The device has two fluid processing units symmetrically mounted on left and right sides of the workbench. Left and right ends of a slender tube, i.e., a workpiece, are connected to the fluid processing units on the left and right sides of the workbench, respectively.

[0014] The magnetic control fluid unit is disposed below the workpiece, and controls magnetic particles in a polishing liquid in the fluid processing units through a magnetic field applied by a magnetic pole to form a magnetic chain with a certain yield strength in a direction of magnetic force and to form a local blocking block adsorbed on an inner surface of the workpiece to reduce an actual aperture for flowing the polishing liquid in the blocking area.

[0015] Each of the fluid processing units comprises a piston, a piston cylinder, a piston rod, a rotating member, a connecting piece and a piston cylinder bracket, wherein the piston cylinder is fixedly connected to the workbench through the piston cylinder bracket, an inner end of the piston rod is fixedly connected to the piston, and the piston rod is slidably connected to an opening of an outer end of the piston cylinder. The piston is slidably connected to an inner surface of the piston cylinder, and a cavity between an inner side of the piston and an inner surface of the piston cylinder is filled with polishing liquid. An outlet of an inner end of the piston cylinder is connected to one end of the rotating member, the other end of the rotating member is connected to the connecting piece, and the other end of the connecting piece clamps an end of the workpiece through an internal snap-fit.

[0016] The magnetic control fluid unit comprises a magnet, a guide rail, a guide rail bracket and a magnetic yoke. The guide rail bracket is disposed below and fixedly connected to the workpiece. The guide rail is installed on the guide rail bracket, and an axial direction of the guide rail is parallel to an axial direction of the workpiece. The magnetic yoke is slidably connected to the guide rail. The magnet is fixed on the magnetic yoke, and a distance between the magnet and the workpiece is 1-3 mm.

[0017] The rotating member comprises a fixed section and a rotating section. The fixed section and the rotating section are connected through an internal bearing, the fixed section is connected to the piston cylinder, and the moving section is connected to the workpiece through the connecting piece.

[0018] Further, the device has three guide rails, which are installed at an equal interval in a plane parallel to the workbench.

[0019] Further, the device has two magnets, which have the same structure and are symmetrically installed on the magnetic yoke disposed at front and rear sides of the workpiece. Each of the magnets comprises a magnetic pole and a magnetic pole tip. The two magnets and the magnetic yoke form an isosceles triangular structure with an upper opening, and a distance between the magnetic pole tip and the workpiece is 1-3 mm.

[0020] Further, a rotation speed of the workpiece is 6-20 rpm.

[0021] Further, the magnets move along the guide rail to perform magnetic field-assisted polishing at each point distributed in an axis direction of the inner surface of the workpiece.

[0022] Further, a polishing medium in the polishing liquid is selected according to a material of the workpiece as follows: cerium oxide is selected when the material of the workpiece is quartz glass, aluminum oxide is selected when the material of the workpiece is stainless steel, and diamond powder is selected when the material of the workpiece is cast iron.

[0023] A abrasive flow polishing method for polishing of an inner surface of slender tubes using the abrasive flow polishing device for polishing of an inner surface of slender tubes that includes the following steps of:

[0024] S1, Selecting, according to the material of the workpiece, an appropriate polishing medium to prepare polishing liquid, stirring the prepared polishing liquid evenly and then filling it into an inner cavity of the piston cylinder;

[0025] S2, Communicating the outlet of the piston cylinder with the rotating member and the connecting piece through threaded connections, connecting the connecting piece with the workpiece through internal snap-fit of the connecting piece, and checking sealing effectiveness of the device after overall connection;

[0026] S3, Placing the magnet on the magnetic yoke, and enabling a distance between the magnetic pole tip and an outer wall of the workpiece to be 1-3 mm;

[0027] S4, Rotating the rotating member through an external transmission device to control the rotation speed of the workpiece at 6-20 rpm;

[0028] S5, Pushing, using an external push rod, the piston rods on left and right sides of the device to move synchronously to ensure that when the piston cylinder at one side of the device pushes out the polishing liquid, the piston cylinder on the other side sucks the polishing liquid, and the piston rod pushes the polishing liquid to flush back and forth against the inner surface of the workpiece, thereby polishing the inner surface of the workpiece;

[0029] S6, Moving the magnet along the guide rail to adsorb magnetic powder in different areas of the workpiece to make the powder attached to tube walls so as to create a blocking effect;

[0030] S7, Stopping the rotation after completion of the processing, removing the workpiece and putting it into an ultrasonic cleaner for cleaning; and

[0031] S8, Completing the polishing process when the inner surface of the processed workpiece (7) meets quality expectations after inspection.

[0032] Compared with the prior art, the present disclosure has the following beneficial effects that:

[0033] 1. The present disclosure adopts a magnet to absorb magnetic particles in magnetorheological polishing liquid flowing in the tube, and the magnetic particles are attached to the tube wall to form a local magnetic block, such that a cross-sectional area of a flow channel in this area is reduced, and a flow rate of magnetic fluid containing polishing abrasive particles increases rapidly in this area, which may controllably change the flow field intensity and polishing intensity of this area.

[0034] 2. The present disclosure adopts a rotary joint to connect the slender tube with the fixed polishing liquid conveying tube and achieve relative rotation therebetween. The rotation of the slender tube ensures a uniformity of selectively polishing an inner surface area of a tube, and increases a relative movement distance between abrasive particles in magnetic fluid and the inner surface of the tube, thereby improving the removal efficiency.

[0035] 3. Compared with traditional abrasive flow polishing methods, the present disclosure, by means of magnetic field-assisted selective polishing, completely solves the problems of on-way attenuation of fluid pressure and uneven polishing, and also the problems of traditional abrasive flow polishing including failure to polish slender tubes with variable apertures and variable roughness. Compared with traditional magnetic grinding, the polishing liquid containing the magnetic fluid is used to solve the problem that the magnetic particles can hardly enter small-aperture slender tubes. Moreover, abrasive particles entrapped by the flow field are mainly used for polishing in the present disclosure, an internal surface of the entire slender tube is subjected to material removal to varying degrees, and polishing efficiency of the present disclosure is much higher than that of the traditional magnetic grinding.

[0036] 4. In the present disclosure, in addition to magnetic abrasive particles, magnetically conductive tools such as iron wires and magnetic needles can also be used for forming flow channel blocks. Due to attractive forces of external magnets, these magnetically conductive tools can be tightly adsorbed on the inner surface of the slender tube, which not only has an effect of blocking the flow field, but also can increase a blocking length in an axial direction of the slender tube.

[0037] 5. To sum up, the present disclosure, based on fluidity of magnetorheological liquid, enables to process slender tubes with extremely small apertures and extremely large length-diameter ratios, such as needle tubes with a length of >200 mm and an inner diameter of ≤1 mm.BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 is a structural schematic diagram of a device of the present disclosure.

[0039] FIG. 2 is a sectional view of a fluid processing unit of the present disclosure (a section line is not shown).

[0040] FIG. 3 is a schematic diagram of a magnetic control fluid unit of the present disclosure.

[0041] FIG. 4 is a sectional view of FIG. 3.

[0042] FIG. 5 is a partial enlarged view of FIG. 4.

[0043] In the figures: 1. piston rod; 2. piston cylinder; 3. piston cylinder bracket; 4. piston; 5. rotating member; 6. connecting piece; 7. workpiece; 8. guide rail bracket; 9. guide rail; 10. magnetic yoke; 11. magnetic pole; 12. magnetic pole tip; and 13. workbench.DETAILED DESCRIPTIONS OF THE EMBODIMENTS

[0044] In order to enable those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure will be described in detail in with reference to the accompanying drawings. The description in this part is exemplary and explanatory only and is not restrictive of the scope of protection of the present disclosure in any way.

[0045] As shown in FIGS. 1 to 5, an abrasive flow polishing device for polishing of inner surface of slender tubes is provided, comprising a workbench 13, fluid processing units and a magnetic control fluid unit. There are two fluid processing units symmetrically mounted on left and right sides of the workbench 13. Left and right ends of a slender tube, i.e., a workpiece 7, are connected to the fluid processing units on the left and right sides of the workbench, respectively.

[0046] The magnetic control fluid unit is disposed below the workpiece 7, and controls magnetic particles in a polishing liquid in the fluid processing units through a magnetic field applied by a magnetic pole 11 to form a magnetic chain with a certain yield strength in a direction of magnetic force and to form a local blocking block adsorbed on an inner surface of the workpiece 7 to reduce an actual aperture for flowing the polishing liquid in the blocking area.

[0047] Each of the fluid processing units comprises a piston 4, a piston cylinder 2, a piston rod 1, a rotating member 5, a connecting piece 6 and a piston cylinder bracket 3. The piston cylinder 2 is fixedly connected to the workbench 13 through the piston cylinder bracket 3, an inner end of the piston rod 1 is fixedly connected to the piston 4, and the piston rod 1 is slidably connected to an opening of an outer end of the piston cylinder 2. The piston 4 is slidably connected to an inner surface of the piston cylinder 2, and a cavity between an inner side of the piston 4 and an inner surface of the piston cylinder 2 is filled with polishing liquid. An outlet of an inner end of the piston cylinder 2 is connected to one end of the rotating member 5, the other end of the rotating member 5 is connected to the connecting piece 6, and the other end of the connecting piece 6 clamps an end of the workpiece 7 through an internal snap-fit.

[0048] The magnetic control fluid unit comprises a magnet, a guide rail 9, a guide rail bracket 8 and a magnetic yoke 10. The guide rail bracket 8 is disposed below and fixedly connected to the workpiece 7. The guide rail 9 is installed on the guide rail bracket 8, and an axial direction of the guide rail 9 is parallel to an axial direction of the workpiece 7. The magnetic yoke10 is slidably connected to the guide rail 9. The magnet is fixed on the magnetic yoke 10, and a distance between the magnet and the workpiece 7 is 1-3 mm.

[0049] The rotating member 5 comprises a fixed section and a rotating section, wherein the fixed section and the rotating section are connected through an internal bearing, the fixed section is connected to the piston cylinder 2, and the moving section is connected to the workpiece (7) through the connecting piece 6.

[0050] Further, the device has three guide rails 9, which are installed at an equal interval in a plane parallel to the workbench 13.

[0051] Further, the device has two magnets, which have the same structure and are symmetrically installed on the magnetic yoke 10 disposed at front and rear sides of the workpiece 7. Each of the magnets comprises a magnetic pole 11 and a magnetic pole tip 12. The two magnets and the magnetic yoke 10 form an isosceles triangular structure with an upper opening, and a distance between the magnetic pole tip 12 and the workpiece 7 is 1-3 mm.

[0052] Further, a rotation speed of the workpiece 7 is 6-20 rpm.

[0053] Further, the magnets move along the guide rail 9 to perform magnetic field-assisted polishing at each point distributed in an axis direction of the inner surface of the workpiece 7. Further, a polishing medium in the polishing liquid is selected according to a material of the workpiece as follows: cerium oxide is selected when the material of the workpiece is quartz glass, aluminum oxide is selected when the material of the workpiece is stainless steel, and diamond powder is selected when the material of the workpiece is cast iron.

[0054] A abrasive flow polishing method for polishing of an inner surface of slender tubes using the abrasive flow polishing device for polishing of an inner surface of slender tubes is provided, including the following steps of:

[0055] S1, Selecting, according to the material of the workpiece 7, an appropriate polishing medium to prepare polishing liquid, stirring the prepared polishing liquid evenly and then filling it into an inner cavity of the piston cylinder 2;

[0056] S2, Communicating the outlet of the piston cylinder 2 with the rotating member 5 and the connecting piece 6 through threaded connections, connecting the connecting piece 6 with the workpiece 7 through internal snap-fit of the connecting piece 6, and checking sealing effectiveness of the device after overall connection;

[0057] S3, Placing the magnet on the magnetic yoke 10, and enabling a distance between the magnetic pole tip 12 and an outer wall of the workpiece 7 to be 1-3 mm;

[0058] S4, Rotating the rotating member 5 through an external transmission device to control the rotation speed of the workpiece 7 at 6-20 rpm;

[0059] S5, Pushing, using an external push rod, the piston rods 1 on left and right sides of the device to move synchronously to ensure that when the piston cylinder 2 at one side of the device pushes out the polishing liquid, the piston cylinder 2 on the other side sucks the polishing liquid, and the piston rod 1 pushes the polishing liquid to flush back and forth against the inner surface of the workpiece 7, thereby polishing the inner surface of the workpiece 7;

[0060] S6, Moving the magnet along the guide rail 9 to adsorb magnetic powder in different areas of the workpiece 7 to make the powder attached to tube walls so as to create a blocking effect;

[0061] S7, Stopping the rotation after completion of the processing, removing the workpiece 7 and putting it into an ultrasonic cleaner for cleaning; and

[0062] S8, Completing the polishing process when the inner surface of the processed workpiece 7 meets quality expectations after inspection.

[0063] A working principle of the present disclosure is as follows:

[0064] Two fluid processing units clamp both ends of the workpiece 7, each of the fluid processing units contains a polishing liquid. The polishing liquid flows through the workpiece 7 at a certain speed and pressure to achieve polishing of the inner surface of the workpiece 7 under the scratching, plowing and abrasion effects of the abrasive particles in the polishing liquid on an inner surface of the workpiece 7.

[0065] A magnetic control fluid unit is located at one side of the workpiece 7, and controls magnetic particles in the polishing liquid through a magnetic field applied by a magnetic pole 11 to form a magnetic chain with a certain yield strength in a direction of a magnetic force and form a blocking block closely attached to the inner surface of the workpiece 7 to change an actual circulation aperture for flowing the polishing liquid in this area and greatly increase a circulation speed of the polishing liquid in this area, thereby improving an efficiency of material removal in this area.

[0066] Each piston cylinder 2 is fixedly connected to a workbench 13 through the piston cylinder bracket 3, for determining a position of the piston cylinder 2 and providing support. The workpiece 7 is arranged between two piston cylinders 2 to ensure that the polishing liquid in an inner cavity of the piston cylinder 2 flows through the inner surface of the workpiece 7 by means of a straight-through manner during operation. The piston 4 is in contact with an inner surface of the piston cylinder 2 and is capable of moving flexibly in the piston cylinder 2, and the piston 4 and the inner surface of the piston cylinder 2 are sealed to ensure that the polishing liquid can be pressurized under the action of the piston 4. An outlet of the piston cylinder 2 is connected to the rotating member 5 to ensure that the piston cylinder 2 can remain fixed when the workpiece 7 rotates, facilitating the operation of the piston 4. The other end of the rotating member 5 is connected to the connecting piece 6, and the other end of the connecting piece 6 clamps the workpiece 7. Each end of the workpiece 7 is connected to a corresponding connecting piece 6 to ensure the sealing effectiveness of the entire device and clamp the workpiece 7 and determine its position.

[0067] The guide rail 9 is suspended below the workpiece 7 through the guide rail bracket 8, and an axial direction of the guide rail 9 is parallel to an axial direction of the workpiece 7, for determining the moving direction and range of the magnet. The magnetic yoke 10 is in contact with the guide rail 9 through holes, which can linearly move on the guide rail 9. The magnet is fixed on the magnetic yoke 10 to ensure that the magnet can linearly move below the workpiece 7, thereby controlling a magnetic field range. The magnet should be close to the workpiece 7 as much as possible to ensure that the polishing liquid in the workpiece 7 can be subjected to a sufficiently large magnetic field force.

[0068] The rotation of the workpiece 7 is achieved by rotating the rotating member 5. The rotating member 5 includes two parts connected by a bearing, enabling one part to rotate while the other part to remain fixed. One end of the rotating member 5 is connected to the piston cylinder 2 and remains fixed, and the other end is communicated with the workpiece 7 through the connecting piece 6 to ensure that the workpiece 7 can rotate together with the rotating member 5.

[0069] The magnet is capable of moving at a constant speed along the guide rail 9 and performs magnetic field-assisted polishing at each point distributed in an axis direction of the inner surface of the workpiece 7, ensuring controllability and uniformity of polishing of the inner surface of the entire workpiece 7.

[0070] An example of the present disclosure is as follows:

[0071] A method was used for polishing an inner surface of an elongated tube including the following steps of:

[0072] S1, Installing and connecting a polishing device according to a process sequence and checking the airtightness of the device.

[0073] S2, Using a workpiece 7 made of stainless steel, with an inner diameter of Φ0.3 mm, an outer diameter of Φ0.6 mm, and an initial roughness of an inner surface of 650 μm. Selecting aluminum oxide as a polishing medium, preparing 200 mL of polishing liquid by mixing the polishing medium with water at a mass ratio of 3:7, stirring the prepared polishing liquid with a magnetic stirrer for 10 min, and filling the evenly stirred polishing liquid into inner cavity of piston cylinder 2 of each of the two fluid processing units.

[0074] S3, Clamping and fixing the workpiece 7 between the two fluid processing units, and both ends of the workpiece 7 are connected to the inner cavities of the piston cylinders 2 through the connecting piece 6 and the rotating member 5 respectively, such that the polishing liquid can enter the workpiece 7 smoothly for processing.

[0075] S4, Pushing and pulling the piston rods 1 on left and right sides of the device sequentially, such that the polishing liquid moves rapidly in the inner cavities of the piston cylinders 2 on the left and right sides and the workpiece 7 to flush the workpiece 1000 times continuously with a flow rate of the polishing liquid of 35 mL / s; and simultaneously, rotating the rotating member 5 to make the workpiece 7 rotate slowly at a speed of 10 rpm.

[0076] S5, Stopping pushing the piston rod 1 when the processing is completed, removing the workpiece 7 made of stainless steel and putting it into an ultrasonic cleaner for cleaning, and drying its inner surface with an air gun to remove any residual polishing liquid.

[0077] S6, Obliquely cutting the processed workpiece 7, and inspecting the qualities of its inner surface at the section, where an overall roughness was about Ra 46 nm, and a local roughness was optimally Ra 32 nm.

[0078] Front, rear, left and right of the present disclosure are only relative to FIG. 1 and do not constitute any limitation on the present disclosure.

[0079] The foregoing embodiments are only preferred embodiments of the present disclosure. It should be pointed out that due to the limitation of literal expression there are infinite concrete structures objectively. For ordinary technicians in the technical field, without departing from the principles of the invention, they can also make some improvements, embellishments or changes, or combine the above technical features in an appropriate way; any modification, change or combination, or direct application of the concept and technical scheme of the invention to other occasions without improvement, shall be deemed as the protection scope of the invention.

Claims

1. An abrasive flow polishing device for polishing of an inner surface of slender tubes, comprising a workbench, fluid processing units and a magnetic control fluid unit, wherein there are two fluid processing units symmetrically mounted on left and right sides of the workbench, and left and right ends of a slender tube, i.e., a workpiece, are connected to the fluid processing units on the left and right sides of the workbench, respectively;the magnetic control fluid unit is disposed below the workpiece, and controls magnetic particles in a polishing liquid in the fluid processing units through a magnetic field applied by a magnetic pole to form a magnetic chain with a certain yield strength in a direction of magnetic force and to form a local blocking block adsorbed on an inner surface of the workpiece to reduce an actual aperture for flowing the polishing liquid in the blocking area;each of the fluid processing units comprises a piston, a piston cylinder, a piston rod, a rotating member, a connecting piece and a piston cylinder bracket, wherein the piston cylinder is fixedly connected to the workbench through the piston cylinder bracket an inner end of the piston rod is fixedly connected to the piston the piston rod is slidably connected to an opening of an outer end of the piston cylinder, the piston is slidably connected to an inner surface of the piston cylinder, a cavity between an inner side of the piston and an inner surface of the piston cylinder is filled with polishing liquid, an outlet of an inner end of the piston cylinder is connected to one end of the rotating member, the other end of the rotating member is connected to the connecting piece, and the other end of the connecting piece clamps an end of the workpiece through an internal snap-fit;the magnetic control fluid unit comprises a magnet, a guide rail, a guide rail bracket and a magnetic yoke, wherein the guide rail bracket is disposed below and fixedly connected to the workpiece, the guide rail is installed on the guide rail bracket, an axial direction of the guide rail is parallel to an axial direction of the workpiece, the magnetic yoke is slidably connected to the guide rail, the magnet is fixed on the magnetic yoke, and a distance between the magnet and the workpiece is 1-3 mm; andthe rotating member comprises a fixed section and a rotating section, wherein the fixed section and the rotating section are connected through an internal bearing, the fixed section is connected to the piston cylinder, and the rotating section is connected to the workpiece through the connecting piece.

2. The abrasive flow polishing device for polishing of an inner surface of slender tubes according to claim 1, wherein the device has three guide rails, which are installed at an equal interval in a plane parallel to the workbench.

3. The abrasive flow polishing device for polishing of an inner surface of slender tubes according to claim 1, wherein the device has two magnets, which have the same structure and are symmetrically installed on the magnetic yoke disposed at front and rear sides of the workpiece, each of the magnets comprises a magnetic pole and a magnetic pole tip, the two magnets and the magnetic yoke form an isosceles triangular structure with an upper opening, and a distance between the magnetic pole tip and the workpiece is 1-3 mm.

4. The abrasive flow polishing device for polishing of an inner surface of slender tubes according to claim 1, wherein a rotation speed of the workpiece is 6-20 rpm.

5. The abrasive flow polishing device for polishing of an inner surface of slender tubes according to claim 1, wherein the magnets move along the guide rail to perform magnetic field-assisted polishing at each point distributed in an axis direction of the inner surface of the workpiece.

6. The abrasive flow polishing device for polishing of an inner surface of slender tubes according to claim 1, wherein a polishing medium in the polishing liquid is selected according to a material of the workpiece as follows: cerium oxide is selected when the material of the workpiece is quartz glass, aluminum oxide is selected when the material of the workpiece is stainless steel, and diamond powder is selected when the material of the workpiece is cast iron.

7. A abrasive flow polishing method for polishing of an inner surface of slender tubes, using the abrasive flow polishing device for polishing of an inner surface of slender tubes according to claim 1, and comprising the following steps of:S1, selecting, according to the material of the workpiece, an appropriate polishing medium to prepare polishing liquid, stirring the prepared polishing liquid evenly and then filling it into an inner cavity of the piston cylinder;S2, communicating the outlet of the piston cylinder with the rotating member and the connecting piece through threaded connections, connecting the connecting piece with the workpiece through internal snap-fit of the connecting piece, and checking sealing effectiveness of the device after overall connection;S3, placing the magnet on the magnetic yoke and enabling a distance between the magnetic pole tip and an outer wall of the workpiece to be 1-3 mm;S4, rotating the rotating member through an external transmission device to control the rotation speed of the workpiece at 6-20 rpm;S5, pushing, using an external push rod, the piston rods on left and right sides of the device to move synchronously to ensure that when the piston cylinder at one side of the device pushes out the polishing liquid, the piston cylinder on the other side sucks the polishing liquid, and the piston rod pushes the polishing liquid to flush back and forth against the inner surface of the workpiece thereby polishing the inner surface of the workpieceS6, moving the magnet along the guide rail to adsorb magnetic powder in different areas of the workpiece to make the powder attached to tube walls so as to create a blocking effect;S7, stopping the rotation after completion of the processing, removing the workpiece and putting it into an ultrasonic cleaner for cleaning; andS8, completing the polishing process when the inner surface of the processed workpiece meets quality expectations after inspection.

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