A method and apparatus for homogeneous polishing of stepped inner surfaces of a partitioned hole

Abstract

The application discloses a partition type step hole inner surface homogeneous polishing method and device, adopts independent polishing liquid circulating system and hydraulic control system, motor drives polishing ring rotation, separates hole shoulder polishing function and hole wall polishing function, realizes partition polishing of hole shoulder and hole wall; through real-time feedback of pressure sensor, realizes accurate control of contact pressure between polishing ring and hole shoulder, after hole shoulder polishing is finished, makes polishing ring continue to adhere to respective corresponding hole shoulder, forms physical shielding to processed hole shoulder, protects processed hole shoulder area from influence of subsequent polishing liquid, effectively avoids secondary flushing or over polishing of processed hole shoulder caused by subsequent high pressure polishing liquid, realizes homogeneous polishing of step hole shoulder and hole wall, makes annular flow cross sections of each hole section equal, reduces risk of blockage of abrasive particles in polishing liquid in annular gap, stabilizes polishing liquid flow rate, and improves uniformity of hole wall polishing of each hole section.

Description

Technical Field

[0001] This invention relates to the field of polishing equipment, and more specifically to a method and apparatus for homogeneous polishing of the inner surface of stepped hole parts with multi-segment diameter variation. Background Technology

[0002] With the development of modern high-end manufacturing equipment towards precision and integration, stepped hole structures are widely used in fields such as machinery manufacturing, aerospace, medical and chemical industries, undertaking key functions such as positioning, connection, sealing, and fluid transmission. Due to the complex geometry of stepped holes, stress concentration often occurs at the hole shoulders, and burrs and microscopic defects are easily generated during processing, directly affecting the assembly accuracy, sealing performance, and service life of parts. Therefore, high-quality polishing is required for the inner walls and shoulders of stepped holes to eliminate defects and achieve a smooth transition; however, traditional polishing methods are insufficient to meet the requirements for stepped holes.

[0003] For polishing the inner surface of holes, existing methods mainly include mechanical polishing, abrasive flow polishing, magnetic abrasive polishing, and electrochemical polishing. Mechanical polishing relies on direct contact friction between the tool and the inner wall. Limited by tool size and rigidity, it is difficult to achieve continuous and homogeneous polishing of the hole section and shoulder. Furthermore, existing mechanical polishing devices are mostly designed for holes of uniform diameter and cannot meet the polishing requirements of holes with varying diameters. Abrasive flow polishing utilizes the flow of a viscoelastic medium containing abrasives for micro-cutting, but eddies and abrupt velocity changes easily occur at the shoulder of stepped holes, leading to inconsistent material removal rates between the shoulder and the hole wall. Insufficient pressure results in ineffective processing, while excessive pressure may damage the already processed surface. Magnetic abrasive polishing uses a magnetic field to control magnetic abrasives to form a flexible abrasive brush. Its removal capacity is small, and for workpieces with large wall thickness or low magnetic permeability, the magnetic field cannot effectively penetrate and precisely control the abrasive distribution within the hole. Magnetic field attenuation is severe in small-diameter sections, resulting in uneven polishing at the shoulder and large-diameter sections. Electrochemical polishing achieves surface leveling through anodic dissolution, but the cathode shape needs to be precisely matched with the complex cavity, which is difficult to design. Furthermore, the electric field distortion at the hole shoulder can easily cause local over-corrosion or insufficient polishing.

[0004] Regarding the polishing technology of the inner surface of stepped holes, Chinese Patent Publication No. CN222945222U proposes a polishing device based on elliptical arc expansion. By rotating the inner elliptical axis, two symmetrically arranged outer polishing shafts expand outward along the expansion groove, realizing the function of entering from the small diameter hole segment and polishing the large diameter hole segment. The problems are: on the one hand, the switching and locking of the polishing diameter depends on manual operation, and continuous adaptive adjustment cannot be achieved during the processing; on the other hand, after the outer polishing shafts expand, they form a whole arc polishing surface, which mainly polishes the overall hole wall, and has limited ability to specifically polish the right angle or rounded corner transition area of ​​the hole shoulder, making it difficult to achieve homogeneous polishing of the hole shoulder and hole wall. Chinese Patent Publication No. CN218785451U proposes a flexible, pneumatically driven, bone-chain polishing structure. Three fingers polish the circumferentially arranged bone chains, each composed of multiple hinged joints. A proportional valve controls the air pressure to bend the bone chains and conform them to stepped holes of different inner diameters. However, this design suffers from several problems: the overall bending of the bone chains primarily aims for radial conformation to the hole wall, making precise control of polishing pressure in localized areas of the hole shoulder difficult; and it lacks a mechanism to isolate and protect the polished surface, easily causing secondary damage. Chinese Patent Publication No. CN203266316U proposes a polishing tool for deep stepped edges and electroplated hard metal deposits in stepped holes. However, this tool suffers from several problems: firstly, the polishing head has a fixed tilt angle, making it impossible to dynamically adjust the polishing pressure during polishing to adapt to different hole shoulder shapes or variations in the thickness of the electroplated deposits; secondly, its open structure allows the processed area to be easily scratched by subsequent moving tools or detached abrasive debris during polishing, making it difficult to achieve in-situ isolation and protection of the processed area.

[0005] Therefore, most of the existing stepped hole inner surface polishing technologies mentioned above are designed for specific diameter variations or overall hole wall polishing, and cannot achieve homogeneous polishing of the hole shoulder and inner wall as well as effective protection of the processed area. Therefore, there is an urgent need for a device and method that can homogeneously polish the stepped hole shoulder and inner wall and protect the processed area in real time during the processing. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems existing in the prior art, and to propose a method and apparatus for homogeneous polishing of the inner surface of stepped holes in a partitioned manner, so as to realize the partitioned polishing of the hole shoulder and the inner wall, form a physical shield, protect the processed hole shoulder area from the influence of subsequent polishing liquid, and thus achieve homogeneous polishing of the stepped hole shoulder and the inner wall.

[0007] To achieve the above objectives, the technical solution adopted by the present invention for a partitioned stepped hole inner surface homogenization polishing device is as follows: A front end cover and a rear end cover are fixedly installed to form a sealed chamber. Inside the chamber is a workpiece with stepped holes arranged horizontally front to back, with the smaller hole end facing forward and the larger hole end facing backward. The front end cover has a liquid inlet at its center that communicates with the smaller hole of the stepped hole. The rear end cover has two liquid outlets at its rear end. The rotating shaft is a stepped shaft, passing through the central through hole at the rear end of the rear end cover. The stepped holes of the workpiece and the stepped shaft of the rotating shaft... An annular gap with equal radial cross-section is formed between the shaft and the motor drive at the rear end. On the shaft outside the rear end cover, bearing one, positioning ring two, and bearing two are fixedly fitted from front to back. Sleeves are fitted around bearing one and bearing two, with the front end of the sleeve fixedly connected to the rear end cover and the rear end fixedly connected to the bearing end cover. The bearing end cover and the shaft are sealed together. Each stepped section of the shaft contains 2-4 horizontally distributed piston cylinders along the circumference. Each piston cylinder is connected to a piston end at the front end. The shaft is sealed, and a polishing ring is coaxially mounted on the front side of each piston cylinder. Each polishing ring is coaxially fixedly connected to the corresponding piston. Multiple hydraulic oil channels are arranged inside the shaft. Each hydraulic oil channel includes an axial channel and a radial channel. The number of radial channels is the same as the number of steps on the shaft, and the number of axial channels is the same as the number of piston cylinders. The front end of each axial channel is connected to the bottom of a piston cylinder, and the rear end of each axial channel is connected to a corresponding radial channel. The polishing fluid tank is connected to the inlet via a polishing fluid circulation pump. Outlet 1 is connected to the polishing fluid tank via a two-position two-way solenoid valve, and outlet 2 is connected to the polishing fluid tank via a two-position two-way solenoid valve. The hydraulic oil tank is connected to the hydraulic oil channels via a bidirectional hydraulic pump and a three-position three-way solenoid valve. A pressure sensor is installed on the pipeline between the hydraulic oil channels and the three-position three-way solenoid valve. The control center is connected to the polishing fluid circulation pump, the bidirectional hydraulic pump, two-position two-way solenoid valves 1, 2, and 3, and the three-position three-way solenoid valve, the motor, and the pressure sensor.

[0008] Furthermore, the outer diameter d of each segment of the stepped shaft and the corresponding inner diameter D of the stepped hole in the workpiece satisfy the following equation: d p τ is the maximum particle size of the abrasive particles in the polishing fluid; k is the anti-clogging safety factor, ranging from 8 to 12; y τ is the yield stress of the polishing slurry. When the polishing slurry does not have a yield stress, τ y Set to 0; L is the total length of the stepped hole; P max τ is the maximum output pressure of the polishing slurry circulation pump. max This represents the maximum permissible wall shear stress of the workpiece material.

[0009] Furthermore, the inner diameter of the polishing ring is consistent with the bore diameter of the workpiece in front of it, and the outer diameter is consistent with the bore diameter of the workpiece in which it is located; the working surface shape of the polishing ring is the same as the corresponding shoulder shape.

[0010] Furthermore, the polishing fluid tank contains polishing fluid, which is a fluid polishing medium formed by dispersing abrasive particles in a carrier fluid. The polishing fluid includes the carrier fluid and the abrasive particles dispersed in the carrier fluid. The abrasive particles are selected from one or more of silicon carbide, alumina, and diamond. The carrier fluid is selected from water-based carrier fluid, oil-based carrier fluid, or viscoelastic carrier fluid with a certain yield stress according to the workpiece material and polishing requirements. Dispersants, thickeners, or corrosion inhibitors are added as needed. The type, particle size, and concentration of abrasive particles are determined according to the workpiece material, stepped hole size, initial surface roughness state, and polishing requirements.

[0011] The technical solution of the present invention, a method for homogeneous polishing of the inner surface of a stepped hole in a partitioned manner, includes the following steps:

[0012] Step 1): The control center starts the motor, the shaft rotates, which drives the polishing ring to rotate. The bidirectional hydraulic pump works in the forward direction, and the three-position three-way solenoid valve is controlled to be in the oil inlet state. The hydraulic oil enters the piston cylinder through the hydraulic oil flow channel, pushing the piston forward and causing the polishing ring to press against its corresponding shoulder. The polishing ring polishes the corresponding shoulder while rotating.

[0013] Step 2): After the hole shoulder polishing reaches the preset requirements, control the motor to stop rotating, maintain the hydraulic pressure in the piston cylinder unchanged, and the polishing ring continues to adhere to its corresponding hole shoulder;

[0014] Step 3): Control the two-position two-way solenoid valve to open and start the polishing fluid circulation pump. The polishing fluid is pumped into the workpiece through the inlet and flows in the annular gap to perform homogeneous polishing on the inner wall of each hole section.

[0015] Furthermore, while in step 1), the pressure sensor detects the hydraulic oil pressure in real time and feeds the detection signal back to the control center. The control center controls the working state of the three-position three-way solenoid valve and adjusts the output of the bidirectional hydraulic pump according to the preset pressure value, so that the contact pressure between the polishing ring and its corresponding shoulder remains stable.

[0016] Furthermore, in step 3), after the polishing fluid flows through the inside of the workpiece, it flows out through the outlet and then returns to the polishing fluid tank through the two-position two-way solenoid valve, realizing the circulation of the polishing fluid; the polishing rings always remain in close contact with their corresponding shoulder holes.

[0017] Furthermore, after the inner walls of each hole section of the workpiece are polished, the control center controls the polishing fluid circulation pump and the two-position two-way solenoid valve one to close, and controls the two-position two-way solenoid valve two to open. The polishing fluid remaining inside the workpiece flows back to the polishing fluid tank through the outlet two and the two-position two-way solenoid valve two in sequence. At the same time, the control center controls the three-position three-way solenoid valve to switch directions and controls the bidirectional hydraulic pump to work in reverse, drawing the hydraulic oil in the piston cylinder back to the hydraulic oil tank. The piston retracts, and the polishing ring disengages from the corresponding hole shoulder and resets.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. This invention employs an independent polishing fluid circulation system and a hydraulic control system, and uses a motor to drive the polishing ring to rotate, separating the polishing function of the inner wall of the stepped hole from the polishing function of the hole shoulder, thereby achieving partitioned polishing of the hole shoulder and the inner wall, solving the problem of uneven processing of the hole shoulder in traditional polishing methods.

[0020] 2. This invention achieves zoned polishing of the hole shoulder and inner wall by setting a polishing ring corresponding to the position of the stepped hole shoulder and using an independent hydraulic system and power system to control the extension and rotation of the polishing ring; at the same time, through real-time feedback from a pressure sensor, it achieves precise control of the contact pressure between the polishing ring and the hole shoulder, further ensuring the polishing quality.

[0021] 3. After the hole shoulder polishing is completed, the present invention allows the polishing ring to continue to adhere to the corresponding hole shoulder, forming a physical shield for the processed hole shoulder, protecting the processed hole shoulder area from the influence of subsequent polishing liquid, effectively avoiding secondary scouring or over-polishing of the processed hole shoulder by the subsequent high-pressure polishing liquid, thereby achieving homogeneous polishing of the stepped hole shoulder and inner wall.

[0022] 4. This invention ensures that the diameter of each working section of the rotating shaft satisfies the formula with the corresponding stepped hole diameter, so that the annular gap between the rotating shaft and the inner wall of the stepped hole is within a suitable hydraulic diameter range, and the annular flow cross-sectional area corresponding to each hole section is equal, thereby reducing the risk of abrasive particles in the polishing fluid clogging in the annular gap, stabilizing the flow rate of the polishing fluid, and improving the uniformity of polishing of the inner wall of each hole section.

[0023] 5. The present invention provides rotational support for the shaft through bearings, and provides stable support and positioning for the shaft through a shaft support and positioning assembly consisting of a sleeve, a rear end cover, a positioning ring, and a bearing end cover. It provides radial and axial positioning for the bearings, avoiding the shaft from being in a cantilevered state without support, and improving the positioning accuracy and rotational stability of the shaft without affecting its rotation.

[0024] 6. This invention isolates polishing fluid, bearing lubricating oil, and external impurities through multiple sealing structures. Seal rings one, two, and four prevent polishing fluid leakage from the workpiece, and seal ring four isolates the polishing fluid and bearing lubricating oil. Simultaneously, seal ring three prevents bearing lubricating oil from flowing out and external impurities from entering the bearing installation space, thereby reducing the risk of polishing fluid contamination and bearing working environment contamination, and improving the stability of the device operation and the cleanliness of the working environment.

[0025] 7. This invention is applicable to stepped hole parts of different specifications. By replacing the rotating shaft, polishing ring and related mounting components of the corresponding size, the polishing requirements of different hole diameters and shoulder shapes can be met, which has good versatility and expandability. Attached Figure Description

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments:

[0027] Figure 1 This is a schematic diagram of the structure of a partitioned stepped hole inner surface homogenization polishing device according to the present invention;

[0028] Figure 2 for Figure 1 A magnified schematic diagram of the three-dimensional structure of the hole shoulder polishing, which consists of the polishing ring, piston, and rotating shaft.

[0029] Figure 3 for Figure 2 A three-dimensional sectional view of the hydraulic oil flow channel inside the rotating shaft;

[0030] Figure 4 for Figure 1 The diagram shows the flow direction of the polishing fluid during polishing operations.

[0031] Figure 5 for Figure 1 The diagram shows the flow direction of the polishing fluid after the polishing process is completed.

[0032] In the diagram: 1. Polishing fluid tank; 2. Polishing fluid circulation pump; 3. Two-position two-way solenoid valve; 4. Bolt; 5. Front end cap; 6. Rear end cap; 7. Workpiece; 8. Sealing ring; 9. Inlet; 10. Shaft; 11. Polishing ring; 12. Piston end cap; 13. Piston; 14. Positioning ring; 15. Polishing ring; 16. Piston end cap; 17. Piston; 18. Hydraulic oil passage; 19. Outlet; 20. Sealing ring; 21. Outlet... 21. Motor; 22. Two-position two-way solenoid valve II; 23. Pressure sensor; 24. Three-position three-way solenoid valve; 25. Two-way hydraulic pump; 26. Hydraulic oil tank; 27. Control center; 28. One-way exhaust valve; 39. Piston cylinder I; 30. Piston cylinder II; 31. Bearing I; 32. Sleeve; 33. Bearing II; 34. Bearing end cap; 35. Sealing ring III; 36. Bolt II; 37. Bolt III; 38. Seal ring IV; 49. Positioning ring II. Detailed Implementation

[0033] like Figure 1 and Figure 2As shown, the present invention discloses a partitioned stepped hole inner surface homogeneous polishing device, comprising a front cover 5 and a rear cover 6. The front cover 5 and the rear cover 6 are fixed together by four circumferentially evenly distributed bolts 4, which define the axial position of the workpiece 7. A cavity for accommodating the workpiece 7 is formed between the front cover 5 and the rear cover 6. The workpiece 7, with stepped holes, is located in this cavity, with the smaller end of the stepped holes facing the front cover 5 and the larger end facing the rear cover 6. The front end face of the workpiece 7 is sealed with the front cover 5 using a sealing ring 8, and the rear end face of the workpiece 7 is sealed with the rear cover 6 using a sealing ring 20. The sealing rings 8 and 20 prevent polishing liquid inside the workpiece 7 from flowing out from the mating points between the front cover 5, the rear cover 6, and the workpiece 7.

[0034] A positioning ring 14 is tightly fitted between the inner wall of the rear cover 6 and the outer wall of the workpiece 7 to position the workpiece 7 radially, so that the central axis of the workpiece 7 coincides with the central axis of the front cover 5 and the rear cover 6, ensuring the coaxiality of the workpiece 7 with the front cover 5 and the rear cover 6.

[0035] A liquid inlet 9 is provided at the center of the front cover 5, which is directly connected to the small hole of the stepped hole, allowing the polishing liquid to enter the stepped hole. Two liquid outlets are provided at the rear end of the rear cover 6, arranged facing each other: outlet 19 and outlet 21. Outlet 19 is located at the upper rear end of the rear cover 6, used to discharge and circulate the polishing liquid during the inner wall polishing process. Outlet 21 is located at the lower rear end of the rear cover 6, used to completely discharge any remaining polishing liquid inside the workpiece 7 after polishing. The rear end of the rear cover 6 has a stepped shaft hole structure with a rearward through hole at the center for mounting the rotating shaft 10.

[0036] The rotating shaft 10 is a stepped shaft, and it is installed concentrically with the stepped hole inside the workpiece 7. The positions of the stepped shaft with the largest and smallest outer diameters of the rotating shaft 10 are consistent with the stepped holes with the largest and smallest inner diameters of the workpiece 7. That is, the front end of the rotating shaft 10 is the smallest outer diameter shaft section, extending into the smallest inner diameter hole of the workpiece 7, and the rear end of the rotating shaft 10 is the largest outer diameter shaft section, extending into the largest inner diameter hole of the workpiece 7. Furthermore, the rear section of the largest outer diameter shaft section of the rotating shaft 10 extends rearward from the central through hole at the rear end of the rear end cover 6, located outside the rear end cover 6. A sealing ring 39 is used to seal between the central through hole of the rear end cover 6 and the rotating shaft 10. The sealing ring 39 serves two purposes: firstly, to prevent the polishing fluid inside the workpiece 7 from leaking along the rotating shaft 10 into the bearing mounting space; and secondly, to prevent bearing lubricating oil from entering the interior of the workpiece 7 and contaminating the polishing environment.

[0037] Along the axial direction of the maximum outer diameter section of the rotating shaft 10 outside the rear end cover 6, bearing 32, locating ring 40, and bearing 34 are sequentially fixed from front to back. Locating ring 40 is positioned between bearing 32 and bearing 34 to limit the axial distance between the two bearings. A sleeve 33 is fitted around bearings 32 and 34, radially limiting the outer rings of the two bearings. The front end of sleeve 33 is fixedly connected to the rear end cover 6 by four bolts 38, evenly distributed around the circumference of sleeve 33. The rear end of sleeve 33 is fixedly connected to bearing end cover 35 by four bolts 37, also evenly distributed around the circumference of sleeve 33. The rear end cover 6 provides axial support to the front side of bearing 32, and bearing end cover 35 provides axial support to the rear side of bearing 34. Locating ring 40 limits the axial position between bearing 32 and bearing 34, thereby achieving axial positioning of the two bearings. Bearing 1 (32) and bearing 2 (34) together support and position the rotating shaft 10, enabling it to rotate stably and preventing it from being in a cantilevered state without support. A sealing ring 36 is used to seal between the bearing end cover 35 and the rotating shaft 10 to prevent bearing lubricating oil from flowing out and to prevent external impurities from entering the bearing mounting space.

[0038] The rotating shaft 10 is a stepped shaft that matches the stepped hole inside the workpiece 7. After installation, the axis of the rotating shaft 10 coincides with the axis of the stepped hole in the workpiece 7. The rotating shaft 10 does not contact the inner wall of the stepped hole in the workpiece 7. A circular gap space is formed between the stepped hole and the stepped shaft. The circular space enclosed by the stepped hole and the stepped shaft is the circular channel space for the flow of polishing fluid. The circular area of ​​the radial section between the stepped hole and the stepped shaft is equal everywhere, that is, the cross-sectional area of ​​the circular channel is equal everywhere, so that the polishing fluid maintains a relatively stable flow rate when flowing through different hole diameter sections, thus achieving uniform polishing.

[0039] The outer diameter d of each segment of the stepped shaft of the rotating shaft 10 is determined according to the corresponding stepped hole of the workpiece 7, and the relationship between the outer diameter d and the inner diameter D of each segment of the corresponding stepped hole of the workpiece 7 satisfies the following formula:

[0040]

[0041] In equation (1): d p τ is the maximum particle size of the abrasive particles in the polishing fluid; k is the anti-clogging safety factor, with a value ranging from 8 to 12; y τ is the yield stress of the polishing slurry. When the polishing slurry does not have a yield stress, τ y Set to 0; L is the total length of the stepped hole; P max τ is the maximum output pressure of the polishing fluid circulation pump 2. maxThis represents the maximum permissible wall shear stress of the workpiece material. The constraint relationship between the outer diameter d and the inner diameter D ensures that the size of the annular gap between the rotating shaft 10 and the workpiece 7 is within the appropriate hydraulic diameter range for abrasive flow polishing. This allows the annular gap to accommodate the passage of abrasive particles in the polishing fluid, thereby preventing abrasive blockage and ensuring that the wall shear stress meets the polishing requirements. It also reduces the risk of abrasive particle blockage within the annular gap and the risk of insufficient or excessive polishing in certain areas.

[0042] The rotating shaft 10 has 2-4 piston cylinders 30 inside the first step from front to back, and the 2-4 piston cylinders 30 are evenly distributed along the circumference of the first step. The second step has 2-4 piston cylinders 31 evenly distributed along the circumference. Similarly, each step has 2-4 piston cylinders evenly distributed along the circumference. Figure 1 Only the stepped shaft 10 is shown, with two steps. Each piston cylinder is mounted horizontally front to back, and the central axis of the piston cylinder is parallel to the central axis of the rotating shaft 10.

[0043] like Figure 2 and Figure 3 As shown, piston 13 is installed in piston cylinder 30 and sealed by piston end cap 12 at the front end. A polishing ring 11 is coaxially and fixedly connected to the front end of piston 13 on the outer side of the front of each piston cylinder 30. Piston 17 is installed in piston cylinder 31 and sealed by piston end cap 16. A polishing ring 15 is coaxially and fixedly connected to piston 17 on the outer side of the front of each piston cylinder 31. Similarly, a polishing ring is coaxially and fixedly connected to the corresponding piston in each piston cylinder. The polishing ring is circular, with its inner diameter matching the diameter of the hole in the workpiece 7 in front of it, and its outer diameter matching the diameter of the hole in the workpiece 7. The polishing ring can move back and forth axially. Two to four piston cylinders are evenly distributed along the circumference of the corresponding steps of the rotating shaft 10 to ensure that the polishing ring is subjected to uniform force. During polishing, the polishing ring is close to the shoulder of the hole, and the contact pressure is consistent.

[0044] The rotating shaft 10 has multiple hydraulic oil channels 18 arranged inside. Each hydraulic oil channel 18 includes an axial channel and a radial channel. The number of radial channels is the same as the number of steps of the rotating shaft 10. The radial channels are located at the rear end of the rotating shaft 10. The number of axial channels is the same as the number of piston cylinders. The front end of each axial channel is connected to the bottom (rear end) of a piston cylinder (e.g., piston cylinder 30 and piston cylinder 31). The rear end of each axial channel is connected to a corresponding radial channel, making the hydraulic oil channels 18 L-shaped. That is, the 2-4 axial channels corresponding to the 2-4 piston cylinders connected to the same polishing ring are all connected to the same radial channel. For example, the 2-4 axial channels connected to the 2-4 piston cylinders 30 are all connected to the first radial channel, and the 2-4 axial channels connected to the 2-4 piston cylinders 31 are all connected to the second radial channel. That is, one radial channel is connected to the corresponding 2-4 axial channels. In this way, hydraulic oil is introduced into multiple axial channels and multiple piston cylinders through one radial channel, driving the piston to extend or retract.

[0045] The rear end of the rotating shaft 10 is connected to the motor 22 via a coupling for driving the rotating shaft 10 to rotate. When the motor 22 starts, it drives the rotating shaft 10 to rotate. The rotating shaft 10 drives the piston 13, piston 2 17, polishing ring 11 and polishing ring 2 15 to rotate synchronously, thereby driving polishing ring 11 and polishing ring 2 15 to rotate. Thus, polishing ring 11 and polishing ring 2 15 are used to polish the corresponding hole shoulders, respectively, to achieve rotary polishing of the hole shoulders.

[0046] A polishing slurry circulation system is provided outside the rear cover 6. This system includes a polishing slurry tank 1, which holds the polishing slurry. The tank 1 is connected to the input of a polishing slurry circulation pump 2 via a pipe, and the output of the pump is connected to the inlet 9 of the front cover 5 via a pipe. The outlet 19 of the rear cover 6 is connected to the input of a two-position two-way solenoid valve 3 via a pipe, and the output of the valve is connected to the polishing slurry tank 1 via a pipe, thus forming a polishing slurry circulation path. A one-way exhaust valve 29 is connected to the outlet 19 via an air inlet branch. In addition, the outlet 21 of the rear cover 6 is connected to the input end of the two-position two-way solenoid valve 23 through a pipe, and the output end of the two-position two-way solenoid valve 23 is connected to the polishing liquid tank 1 to form a drainage system for quickly draining the polishing liquid when the work is finished. During the drainage process, the pressure difference between the inside and outside of the workpiece 7 is used to balance the pressure inside and outside of the workpiece 7, so that the polishing liquid remaining inside the workpiece 7 can be smoothly drained back to the polishing liquid tank 1 through the outlet 21.

[0047] The polishing fluid in polishing fluid tank 1 is a fluid polishing medium formed by dispersing abrasive particles in a carrier fluid. It includes the carrier fluid and the abrasive particles dispersed within it. The abrasive particles can be one or more of silicon carbide, alumina, and diamond. The carrier fluid can be water-based, oil-based, or a viscoelastic carrier fluid with a certain yield stress, depending on the workpiece material and polishing requirements. Dispersants, thickeners, or corrosion inhibitors can be added as needed. The type, particle size, and concentration of the abrasive particles are determined based on the workpiece material, stepped hole size, initial surface roughness, and polishing requirements. The maximum particle size d of the abrasive particles is specified in the text. p The annular gap condition defined by equation (1) should be satisfied.

[0048] Hydraulic control system: Hydraulic oil is stored in hydraulic oil tank 27. Hydraulic oil tank 27 is connected to the input end of bidirectional hydraulic pump 26 through a pipeline. The output end of bidirectional hydraulic pump 26 is connected to the input end of three-position three-way solenoid valve 25 through a pipeline. The output end of three-position three-way solenoid valve 25 is connected to each piston cylinder through hydraulic oil flow channel 18 inside rotating shaft 10, such as the bottom of piston cylinder 30 and piston cylinder 31. A pressure sensor 24 is installed in the hydraulic oil passage, on the hydraulic pipeline between hydraulic oil flow channel 18 and three-position three-way solenoid valve 25, to detect hydraulic oil pressure and feed back pressure signals to control center 28.

[0049] The control center 28 is connected to the polishing fluid circulation pump 2, the bidirectional hydraulic pump 26, the two-position two-way solenoid valve 3, the two-position two-way solenoid valve 23, the three-position three-way solenoid valve 25, the motor 22, and the pressure sensor 24, respectively, to realize the automatic control of each controlled component and to receive signals from the pressure sensor 24. Based on the feedback signal from the pressure sensor 24, the control center 28 controls the working state of the three-position three-way solenoid valve 25 and adjusts the output of the bidirectional hydraulic pump 26, so that the polishing ring 11 and the polishing ring 25 apply stable contact pressure to their respective corresponding shoulder holes, and controls the shoulder polishing, shoulder protection, inner wall polishing, fluid drainage, and reset processes according to a preset program.

[0050] The working process of the device of the present invention is as follows:

[0051] Step 1: Installation and Positioning. Install positioning ring 14 between the rear end cover 6 and the workpiece 7. Place workpiece 7 between the front end cover 5 and the rear end cover 6, and fix the front end cover 5, workpiece 7, and rear end cover 6 with four bolts 4. Positioning ring 14 radially positions workpiece 7, aligning the axis of the stepped hole of workpiece 7 with the central axis of the rear end cover 6. Insert the rotating shaft 10 from the rear forward through the central through hole of the rear end cover 6 and into the workpiece 7. Install bearing 32, positioning ring 40, and bearing 34 sequentially along the axial direction of the rotating shaft 10, positioning ring 40 between bearing 32 and bearing 34. Then, sleeve 33 is fitted over bearing 32 and bearing 34, and fixed to the rear end cover 6 with bolt 38. Finally, fixed bearing end cover 35 to sleeve 33 with bolt 37, thus completing the support and positioning of the rotating shaft 10.

[0052] Step 2: Shoulder Polishing. Control center 28 starts motor 22, which drives shaft 10 to rotate via coupling, thereby rotating polishing ring 11 and polishing ring 25. Simultaneously, control center 28 controls bidirectional hydraulic pump 26 to operate in the forward direction and controls three-position three-way solenoid valve 25 to be in the oil inlet state, allowing hydraulic oil to enter piston cylinder 1 30 and piston cylinder 2 31 through hydraulic oil flow channel 18, pushing piston 1 13 and piston 2 17 forward, causing polishing ring 11 and polishing ring 2 15 to press against their respective shoulder. At the same time, pressure sensor 24 monitors the hydraulic oil pressure in real time and feeds the detection signal back to control center 28. Control center 28 controls the operating state of three-position three-way solenoid valve 25 and adjusts the output of bidirectional hydraulic pump 26 according to the preset pressure value, maintaining stable contact pressure between polishing ring 11 and polishing ring 2 15 and their respective shoulder. Polishing ring 11 and polishing ring 2 15 polish their respective shoulders while rotating until the preset polishing requirements are met.

[0053] Step 3: Shoulder Protection. After the shoulder polishing reaches the preset requirements, the control center 28 controls the motor 22 to stop rotating, and controls the bidirectional hydraulic pump 26 and the three-position three-way solenoid valve 25 according to the pressure signal fed back by the pressure sensor 24, maintaining the hydraulic pressure in piston cylinder 1 30 and piston cylinder 2 31 unchanged, so that piston 1 13 and piston 2 17 remain in the extended state. At this time, polishing ring 11 and polishing ring 2 15 continue to adhere to their respective corresponding shoulder, forming a physical shield for the polished shoulder. This shielding state continues until the subsequent inner wall polishing process is completed.

[0054] Step 4: Polish the inner wall. (For example...) Figure 4As shown, the control center 28 controls the two-position two-way solenoid valve 3 to open and start the polishing slurry circulation pump 2. The polishing slurry circulation pump 2 pumps the polishing slurry in the polishing slurry tank 1 into the workpiece 7 through the inlet 9. The polishing slurry flows in the annular channel formed between the inner wall of the stepped hole of the workpiece 7 and the outer wall of the rotating shaft 10. The abrasive particles in the polishing slurry come into contact with the inner wall of the stepped hole under the action of the flow, and polish the inner wall of each hole segment. After the polishing slurry flows into the workpiece 7, it flows out through the outlet 19 and then returns to the polishing slurry tank 1 through the two-position two-way solenoid valve 3, realizing the circulation of the polishing slurry. During this process, the polishing ring 11 and the polishing ring 15 always remain in close contact with their respective hole shoulders to avoid the polishing slurry directly acting on the polished hole shoulders. Since the annular flow cross-sectional area corresponding to each hole segment is equal, the flow velocity of the polishing slurry remains stable when flowing through different hole diameter segments, thereby improving the uniformity of polishing of the inner wall of each hole segment.

[0055] Step 5: Drainage and Reset. After the inner wall of workpiece 7 is polished, the control center 28 controls the polishing fluid circulation pump 2 and the two-position two-way solenoid valve 3 to close, and controls the two-position two-way solenoid valve 23 to open. The one-way air inlet valve 29 is opened under the action of the pressure difference between the inside and outside of workpiece 7 and balances the pressure inside and outside of workpiece 7, so that the polishing fluid remaining inside workpiece 7 flows back to the polishing fluid tank 1 through the outlet 21 and the two-position two-way solenoid valve 23 in sequence. Figure 5 As shown. Simultaneously, the control center 28 controls the three-position three-way solenoid valve 25 to switch directions and controls the bidirectional hydraulic pump 26 to operate in reverse, drawing the hydraulic oil from piston cylinder 1 30 and piston cylinder 2 31 back to the hydraulic oil tank 27, causing piston 1 13 and piston 2 17 to retract, and polishing ring 1 11 and polishing ring 2 15 to disengage from their corresponding shoulders and reset. After drainage and reset are completed, bolt 1 4 is removed, workpiece 7 is taken off, and the entire polishing process is completed.

[0056] In this invention, the inner diameter D of the polishing ring 11 11 The outer diameter D of the polishing ring-11 is equal to the diameter of the first section of the 7-step hole on the workpiece. 12 The second section of the stepped hole in the workpiece has the same diameter as the second section of the hole; the working surface shape of polishing ring 11 is the same as the shoulder shape between the first and second hole sections; the inner diameter D of polishing ring 15 is... 21 The outer diameter D of the polishing ring 15 is equal to the second section diameter of the 7-step hole on the workpiece. 22 The diameter of the third segment of the stepped hole in workpiece 7 is equal to that of the working surface of polishing ring 15, and the shape of the shoulder between the second and third segments is the same. For stepped hole workpieces with different hole diameters, number of segments, or shoulder shapes, the diameter and length of each stepped shaft working segment of rotating shaft 10 can be adjusted accordingly, and polishing rings and related mounting components that match the shoulder can be replaced.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications, equivalent substitutions, and improvements can be made to the present invention without departing from its spirit and principles, and all such modifications, equivalent substitutions, and improvements should be included within the scope of protection of the present invention.

Claims

1. A partitioned stepped hole inner surface homogenization polishing device, wherein a front end cover and a rear end cover are fixedly installed to form a sealed chamber, and the chamber contains a workpiece with stepped holes arranged horizontally front to back, the smaller hole end of the workpiece facing forward and the larger hole end facing backward, characterized in that: The front cover has a liquid inlet (9) at the center that communicates with the small hole of the stepped hole, and the rear cover has a liquid outlet one and a liquid outlet two at the rear end; the rotating shaft (10) is a stepped shaft that passes through the central through hole at the rear end of the rear cover. The stepped hole of the workpiece and the stepped shaft of the rotating shaft (10) form an annular gap with equal radial cross sections at each point. The rear end of the rotating shaft (10) is connected to the motor drive. On the rotating shaft (10) outside the rear end cover, bearing one, positioning ring two and bearing two are fixedly sleeved from front to back. Bearing one and bearing two are sleeved on the outside. The front end of the sleeve is fixedly connected to the rear end cover and the rear end is fixedly connected to the bearing end cover. The bearing end cover and the rotating shaft (10) are sealed. The rotating shaft (10) has 2 to 4 piston cylinders evenly distributed around the circumference in each stepped shaft step. Each piston cylinder is closed by the piston end cap at the front end. A polishing ring is coaxially provided on the front side of each piston cylinder. Each polishing ring is coaxially fixedly connected to the corresponding piston. The rotating shaft (10) has multiple hydraulic oil channels (18) arranged inside. Each hydraulic oil channel (18) includes an axial channel and a radial channel. The number of radial channels is the same as the number of steps of the rotating shaft (10), and the number of axial channels is the same as the number of piston cylinders. The front end of each axial channel is connected to the bottom of a piston cylinder, and the rear end of each axial channel is connected to a corresponding radial channel. The polishing liquid tank (1) is connected to the inlet (9) via the polishing liquid circulation pump (2), and the outlet is connected to the polishing liquid tank (1) via the two-position two-way solenoid valve (3), and the outlet is connected to the polishing liquid tank (1) via the two-position two-way solenoid valve (23). The hydraulic oil tank (27) is connected to the hydraulic oil passage (18) via a two-way hydraulic pump (26) and a three-position three-way solenoid valve (25). A pressure sensor (24) is installed on the pipeline between the hydraulic oil passage (18) and the three-position three-way solenoid valve (25). The control center (28) is connected to the polishing fluid circulation pump (2), the bidirectional hydraulic pump (26), the two-position two-way solenoid valve one (3), the two-position two-way solenoid valve two (23), the three-position three-way solenoid valve (25), the motor, and the pressure sensor (24).

2. The partitioned stepped hole inner surface homogenization polishing device according to claim 1, characterized in that: The outer diameter d of each segment of the stepped shaft of the rotating shaft (10) and the inner diameter D of the corresponding stepped hole of the workpiece satisfy the following formula: d p τ is the maximum particle size of the abrasive particles in the polishing fluid; k is the anti-clogging safety factor, ranging from 8 to 12; y τ is the yield stress of the polishing slurry. When the polishing slurry does not have a yield stress, τ y Set to 0; L is the total length of the stepped hole; P max The maximum output pressure of the polishing fluid circulation pump (2); τ max This represents the maximum permissible wall shear stress of the workpiece material.

3. The partitioned stepped hole inner surface homogenization polishing device according to claim 1, characterized in that: The inner diameter of the polishing ring is the same as the hole diameter of the workpiece in front of it, and the outer diameter is the same as the hole diameter of the workpiece it is in; the working surface shape of the polishing ring is the same as the corresponding shoulder shape.

4. The partitioned stepped hole inner surface homogenization polishing device according to claim 1, characterized in that: The polishing fluid tank (1) contains polishing fluid. The polishing fluid is a fluid polishing medium formed by dispersing abrasive particles in a carrier fluid. It includes the carrier fluid and the abrasive particles dispersed in the carrier fluid. The abrasive particles are selected from one or more of silicon carbide, alumina, and diamond. The carrier fluid is selected from water-based carrier fluid, oil-based carrier fluid, or viscoelastic carrier fluid with a certain yield stress according to the workpiece material and polishing requirements. Dispersants, thickeners, or corrosion inhibitors are added as needed. The type, particle size, and concentration of abrasive particles are determined according to the workpiece material, stepped hole size, initial surface roughness state, and polishing requirements.

5. The partitioned stepped hole inner surface homogenization polishing device according to claim 1, characterized in that: A positioning ring (14) is tightly fitted between the inner wall of the rear cover and the outer wall of the workpiece to position the workpiece radially.

6. A polishing method for a partitioned stepped hole inner surface homogeneous polishing device as described in claim 1, characterized in that... Includes the following steps: Step 1): The control center (28) starts the motor, the shaft (10) rotates, driving the polishing ring to rotate, the bidirectional hydraulic pump (26) works in the forward direction, and controls the three-position three-way solenoid valve (25) to be in the oil inlet state. The hydraulic oil enters the piston cylinder through the hydraulic oil flow channel (18), pushing the piston forward and causing the polishing ring to press against its corresponding shoulder. The polishing ring polishes the corresponding shoulder in the rotating state. Step 2): After the hole shoulder polishing reaches the preset requirements, control the motor to stop rotating, maintain the hydraulic pressure in the piston cylinder unchanged, and the polishing ring continues to adhere to its corresponding hole shoulder; Step 3): Control the two-position two-way solenoid valve (3) to open and start the polishing liquid circulation pump (2). The polishing liquid is pumped into the workpiece through the inlet (9) and flows in the annular gap to perform homogeneous polishing on the inner wall of each hole section.

7. The polishing method according to claim 6, characterized in that: While in step 1), the pressure sensor (24) detects the hydraulic oil pressure in real time and feeds the detection signal back to the control center (28). The control center (28) controls the working state of the three-position three-way solenoid valve (25) and adjusts the output of the bidirectional hydraulic pump (26) according to the preset pressure value, so that the contact pressure between the polishing ring and its corresponding shoulder remains stable.

8. The polishing method according to claim 6, characterized in that: In step 3), after the polishing liquid flows through the inside of the workpiece, it flows out through the outlet (19) and then returns to the polishing liquid tank (1) through the two-position two-way solenoid valve (3) to realize the circulation of the polishing liquid; the polishing ring always stays close to its corresponding shoulder.

9. The polishing method according to claim 6, characterized in that: After the inner wall of each hole section of the workpiece is polished, the control center (28) controls the polishing fluid circulation pump (2) and the two-position two-way solenoid valve (3) to close, and controls the two-position two-way solenoid valve (23) to open. The polishing fluid remaining inside the workpiece flows back to the polishing fluid tank (1) through the outlet (21) and the two-position two-way solenoid valve (23). At the same time, the control center (28) controls the three-position three-way solenoid valve (25) to switch, and controls the bidirectional hydraulic pump (26) to work in reverse, drawing the hydraulic oil in the piston cylinder back to the hydraulic oil tank (27). The piston retracts, and the polishing ring disengages from the corresponding hole shoulder and resets.

10. The polishing method according to claim 6, characterized in that: For workpieces with stepped holes of different diameters, number of hole segments or shoulder shapes, adjust the diameter and length of each stepped shaft of the rotating shaft (10) and replace the polishing ring that matches the shoulder.

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