Double-sided cooperative polishing system and polishing method based on time-varying modulation of abrasive belt rotating speed

Abstract

The application relates to the technical field of optical processing, in particular to a double-face cooperative polishing system and method based on time-varying modulation of a sand belt rotating speed, which comprises an inner surface processing robot, an outer surface processing robot, a workpiece supporting platform, a central control module and a workpiece rotation driving module; the method first measures an error matrix of inner and outer surfaces of a workpiece to be processed, presets a full-aperture processing path shared by the two robots, calculates the residence time of each discrete point according to the length of the processing path, solves the instantaneous linear speed of the sand belt polishing assembly of the inner and outer surfaces according to the target removal amount of the inner and outer surfaces, generates a control file executable by the double robots and the sand belt polishing assembly, and completes double-face cooperative polishing processing. The time-varying modulation of the sand belt rotating speed is used to replace the traditional residence time control, double-face cooperative polishing processing of the workpiece to be processed is realized, the reference eccentricity problem caused by secondary clamping is avoided, and the overall processing efficiency is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of optical processing technology, and particularly relates to a double-sided collaborative polishing system and polishing method based on time-varying modulation of belt rotation speed. Background Technology

[0002] Conformal fairings, as key aero-optical components of high-speed aircraft, are typically made of hard and brittle materials such as sapphire, spinel, or high-strength glass. Their shapes are often highly steep, streamlined bodies of revolution, and they require extremely high uniformity in wall thickness and surface precision. This means that the manufacturing process must not only solve the problem of efficiently removing hard and brittle materials but also overcome the technological challenges posed by geometric features such as deep cavities, thin walls, and variable curvature. Currently, deterministic polishing technologies for high-precision optical components mainly include Computer Controlled Optical Surfacing (CCOS, typically achieved using small grinding heads), magnetorheological polishing, ion beam shaping, and gasbag polishing. While these technologies perform well in machining planar or low-steep aspherical surfaces, they suffer from several inherent drawbacks when dealing with deep cavities and high-steep fairings: 1. Poor geometric interference and accessibility: Magnetorheological polishing wheels, airbag polishing heads, and traditional CCOS grinding discs are relatively large, making them prone to mechanical interference with the workpiece's inner wall when machining the inner surface of the fairing (especially the pointed deep cavity region), resulting in "incomplete grinding" or "workpiece damage." 2. Low surface fit: Hardened small grinding heads struggle to adapt to the drastically changing curvature of the fairing's inner and outer surfaces, easily generating a "edge effect" of localized pressure concentration; while ion beam shaping, although non-contact, has extremely low removal efficiency, making it unsuitable for mass production of fairings. 3. Processing efficiency bottleneck: The aforementioned technologies typically employ a "single-point contact" removal mode, and due to limitations in tool rigidity or removal mechanisms, it is difficult to achieve large-scale material removal while maintaining the surface shape.

[0003] In contrast, robotic belt polishing technology, with its flexible contact, cold cutting, and long cantilever, has become an ideal solution to the challenges of fairing machining. The rubber contact wheel of the abrasive belt has good elasticity, which can adapt to changes in the curvature of the fairing surface; and the slender cantilever structure of the abrasive belt can polish the narrow inner cavities of the fairing, effectively solving the problem of machinability of deep cavities. At the same time, the abrasive belt has a high linear speed, and the material removal rate is far superior to traditional polishing methods.

[0004] Despite the advantages of belt polishing, existing fairing processing technologies generally employ a step-by-step, sequential processing mode, starting with the inner surface and working outwards. This mode is not only inefficient, but the secondary mounting inevitably introduces positioning errors, causing the rotation centers of the inner and outer surfaces to misalign, severely compromising wall thickness uniformity. Although dual-robot collaborative processing technology has been proposed to address the efficiency issue, existing dual-robot collaborative solutions are limited by the collision avoidance requirements of "trajectory space synchronization," and the feed speed (dwell time) of the collaborative robots must be strictly consistent. This creates a new contradiction: when the error distributions of the inner and outer surfaces are inconsistent, the material removal rate modulation mode based on dwell time cannot simultaneously meet the shaping requirements of both sides. Summary of the Invention

[0005] In view of this, the present invention aims to provide a double-sided collaborative polishing system and polishing method based on time-varying belt speed modulation, which replaces the traditional dwell time control with time-varying belt speed modulation to achieve collaborative polishing of both the inner and outer sides of the workpiece.

[0006] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A double-sided collaborative polishing system based on time-varying modulation of belt rotation speed includes: an inner surface processing robot (1), an outer surface processing robot (2), a workpiece support platform (3), a central control module (4), and a workpiece rotation drive module (5). An inner surface sanding belt polishing assembly (7) is fixedly installed on the end effector of the inner surface machining robot (1); an outer surface sanding belt polishing assembly (8) is fixedly installed on the end effector of the outer surface machining robot (2); The workpiece rotation drive module (5) is fixedly installed on the workpiece support platform (3) to fix the workpiece (6) to be processed and drive it to rotate; The central control module (4) is used to control the synchronous movement of the inner surface processing robot (1) and the outer surface processing robot (2) and to control the belt speed of the inner surface sanding belt polishing assembly (7) and the outer surface sanding belt polishing assembly (8) to complete the double-sided collaborative processing of the workpiece (6).

[0007] Furthermore, both the inner surface processing robot (1) and the outer surface processing robot (2) are six-degree-of-freedom robotic arms.

[0008] Furthermore, the central control module (4) includes a host computer computing unit, a main controller, and a communication network; The host computer computing unit is used to calculate the instantaneous linear velocity of the sanding belt of the inner surface sanding belt polishing assembly (7) and the outer surface sanding belt polishing assembly (8); the main controller is used to control the inner surface processing robot (1) and the outer surface processing robot (2) to perform synchronous trajectory movement and receive the instantaneous linear velocity of the sanding belt calculated by the host computer computing unit, and adjust the sanding belt speed of the inner surface sanding belt polishing assembly (7) and the outer surface sanding belt polishing assembly (8) independently in real time through the communication network.

[0009] Furthermore, the workpiece rotation drive module (5) includes an auxiliary support frame (9), a motor (10), a main support plate (11), an active synchronous pulley (12), a synchronous belt (13), and a driven synchronous pulley (14); Among them, the auxiliary support frame (9) and the main support plate (11) are both fixed on the workpiece support platform (3); the motor (10) is fixed on one side of the main support plate (11), and the active synchronous pulley (12) and the driven synchronous pulley (14) are located on the other side of the main support plate (11); the output shaft of the motor (10) is connected to the active synchronous pulley (12), the driven synchronous pulley (14) is rotatably connected to the main support plate (11), and the synchronous belt (13) is tensioned on the driven synchronous pulley (14) and the active synchronous pulley (12); the bottom of the workpiece (6) is fixedly connected to the side of the driven synchronous pulley (14) through a flange, and the top of the workpiece (6) is placed on the auxiliary support frame (9) to limit the radial degree of freedom of the workpiece (6) and prevent its chatter.

[0010] Furthermore, the auxiliary support frame (9) adopts external roller contact support. The rollers that can rotate freely are arranged in a three-point or V-shape on the auxiliary support frame (9). The outer edge of the roller contacts the top outer wall of the workpiece (6) to form a contact radial constraint.

[0011] Furthermore, both the inner surface sanding belt polishing assembly (7) and the outer surface sanding belt polishing assembly (8) include a servo motor, a drive wheel driven by the servo motor, an elastic contact wheel that contacts the workpiece (6), a sanding belt tensioned between the drive wheel and the elastic contact wheel, and a drive force control flange; wherein, the elastic contact wheel presses the working section of the sanding belt against the surface of the workpiece (6); the inner surface sanding belt polishing assembly (7) and the outer surface sanding belt polishing assembly (8) sense the normal contact force in real time through the drive force control flange, and maintain a constant contact center pressure through closed-loop control; the instantaneous linear velocity of the sanding belt is the surface linear velocity of the working section of the sanding belt along its running direction, which is independently driven by the servo motor through the drive wheel, responding to the sanding belt speed command of the central control module (4).

[0012] Furthermore, the workpiece to be processed (6) is a fairing, an aircraft engine nozzle, a ceramic antenna cover, or a deep-sea pressure-resistant glass cover.

[0013] A dual-sided collaborative polishing method based on time-varying belt rotation speed modulation, implemented using a dual-sided collaborative polishing system, includes the following steps: S1: Based on the measurement equipment, full-diameter scanning of the inner and outer surfaces of the workpiece (6) is performed to obtain discrete point cloud data; the discrete point cloud data is mapped to a unified workpiece coordinate system through an interpolation algorithm to obtain the inner surface error matrix. and outer surface error matrix ; S2: In the workpiece coordinate system, design a full-diameter machining path shared by the inner surface machining robot (1) and the outer surface machining robot (2), and set the reference feed rate of both the inner surface machining robot (1) and the outer surface machining robot (2) to be... Calculate each discrete point on the machining path based on its length. Duration of stay ; S3: Discrete each point on the inner and outer surfaces of the workpiece (6) Target removal amount corresponding to surface error and Substitute them into the Preston equation to solve for the instantaneous linear velocity of the abrasive belt corresponding to the inner surface abrasive belt polishing component (7) and the outer surface abrasive belt polishing component (8); S4: Generate executable synchronous motion control files for the inner surface processing robot (1) and the outer surface processing robot (2) based on the processing path, and generate executable sand belt speed control files for the inner surface sand belt polishing component (7) and the outer surface sand belt polishing component (8) based on the instantaneous linear velocity of the sand belt, to complete the double-sided collaborative polishing process.

[0014] Furthermore, in step S2, the residence time The calculation formula is: ; in, For the first on the processing path The arc length of the path element corresponding to each discrete point; At each discrete point Dwell time of the inner surface processing robot (1) Dwell time of the external surface processing robot (2) Because they share the same machining path and the same baseline feed rate, they are forced to be identical and are all set to the same value. .

[0015] Furthermore, in step S3, the instantaneous linear velocity of the inner surface abrasive belt polishing assembly (7) is... and the instantaneous linear velocity of the abrasive belt in the outer surface abrasive belt polishing assembly (8) The calculation formula is: ; ; in, This is the process coefficient. This represents the pressure at the contact center.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) By modulating the sanding belt speed in a time-varying manner, this invention optimizes the adjustment method of the target removal amount on the surface of the workpiece from the traditional dwell time control to the sanding belt speed time-varying modulation control, based on the fact that the processing path of the workpiece remains unchanged, and by utilizing the high-frequency response characteristics of the servo motor, the double-sided collaborative polishing processing of the workpiece is realized. In addition, this invention does not require secondary clamping of the workpiece, avoiding the reference eccentricity problem caused by secondary clamping. From the perspective of physical structure, it ensures that the rotation center height of the inner and outer surfaces of the workpiece is highly coincident, effectively eliminating positioning errors. Moreover, the double-sided collaborative polishing processing mode greatly improves the overall processing efficiency.

[0017] (2) The present invention adopts a synchronous belt drive combined with an open architecture workpiece rotation drive module, which effectively expands the internal operating space of deep cavity thin-walled workpieces to be processed, so that the elastic contact wheel in the sand belt polishing assembly can penetrate into the bottom area of ​​the workpiece to be processed without obstruction to complete the polishing process, realizing full coverage processing of the entire diameter of the workpiece without dead angles, and solving the technical problem that traditional equipment is difficult to process the bottom of the deep cavity of the workpiece.

[0018] (3) The present invention is equipped with an auxiliary support frame with flexible support points, which forms a stable double-end support constraint structure with the driven synchronous pulley fixedly connected to the bottom of the workpiece. At the same time, in conjunction with the force balance effect of the normal alignment machining stroke of the dual robots, the normal grinding force during the polishing process is effectively offset, and the stress deformation and machining vibration of the workpiece are suppressed. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the structure of the double-sided collaborative polishing system based on time-varying belt rotation speed modulation as described in the embodiment of the present invention; Figure 2 A schematic diagram of the workpiece rotation drive module described in an embodiment of the present invention; Figure 3 This is a schematic flowchart of the double-sided collaborative polishing method based on time-varying belt rotation speed modulation, as described in an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1. Inner surface machining robot; 2. Outer surface machining robot; 3. Workpiece support platform; 4. Central control module; 5. Workpiece rotation drive module; 6. Workpiece to be processed; 7. Inner surface sanding belt polishing assembly; 8. Outer surface sanding belt polishing assembly; 9. Auxiliary support frame; 10. Motor; 11. Main support plate; 12. Active synchronous pulley; 13. Synchronous belt; 14. Driven synchronous pulley. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0023] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] like Figures 1 to 2 As shown, this embodiment provides a double-sided collaborative polishing system based on time-varying modulation of belt rotation speed, comprising an inner surface processing robot 1, an outer surface processing robot 2, a workpiece support platform 3, a central control module 4, and a workpiece rotation drive module 5.

[0027] An inner surface sanding belt polishing assembly 7 is fixedly installed on the end effector of the inner surface machining robot 1; an outer surface sanding belt polishing assembly 8 is fixedly installed on the end effector of the outer surface machining robot 2.

[0028] Both the inner surface sanding belt polishing assembly 7 and the outer surface sanding belt polishing assembly 8 include a servo motor, a drive wheel driven by the servo motor, an elastic contact wheel that contacts the workpiece 6, a sanding belt tensioned between the drive wheel and the elastic contact wheel, and a drive force control flange. The elastic contact wheel presses the working section of the sanding belt against the surface of the workpiece 6. The inner surface sanding belt polishing assembly 7 and the outer surface sanding belt polishing assembly 8 sense the normal contact force in real time through the drive force control flange and maintain a constant contact center pressure through closed-loop control. The instantaneous linear velocity of the sanding belt is the surface linear velocity of the working section of the sanding belt along its running direction, which is independently driven by the servo motor through the drive wheel and responds to the sanding belt speed command of the central control module 4.

[0029] The inner surface processing robot 1 and the outer surface processing robot 2 are installed on both sides of the workpiece 6 to be processed. The inner surface processing robot 1 adopts a slender arm structure and uses the open space reserved by the workpiece rotation drive module 5 to go deep into the interior of the workpiece 6 to perform operations. The outer surface processing robot 2 is arranged on the side and is responsible for processing the outer surface of the workpiece 6. The two robots are calibrated in a global coordinate system and share a unified workpiece coordinate system, which can achieve collaborative operation.

[0030] In some embodiments, both the inner surface processing robot 1 and the outer surface processing robot 2 are six-degree-of-freedom robotic arms.

[0031] In some embodiments, the workpiece 6 to be processed can be a fairing, an aircraft engine nozzle, a ceramic antenna radome, or a deep-sea pressure-resistant glass cover.

[0032] The workpiece rotation drive module 5 is fixedly installed on the workpiece support platform 3 to fix the workpiece 6 to be processed and drive it to rotate.

[0033] like Figure 2As shown, the workpiece rotation drive module 5 includes an auxiliary support frame 9, a motor 10, a main support plate 11, a driving synchronous pulley 12, a synchronous belt 13, and a driven synchronous pulley 14. The auxiliary support frame 9 and the main support plate 11 are both fixed to the workpiece support platform 3. The motor 10 is fixed to one side of the main support plate 11, and the driving synchronous pulley 12 and the driven synchronous pulley 14 are located on the other side of the main support plate 11. The output shaft of the motor 10 is connected to the driving synchronous pulley 12, and the driven synchronous pulley 14 is rotatably connected to the main support plate 11. The synchronous belt 13 is tensioned on the driven synchronous pulley 14 and the driving synchronous pulley 12. The bottom of the workpiece 6 is fixedly connected to the side of the driven synchronous pulley 14 via a flange, and the top of the workpiece 6 is placed on the auxiliary support frame 9 to restrict the radial degree of freedom of the workpiece 6 and prevent its chatter.

[0034] To address the issues of traditional rotary table surfaces obstructing the robot's feed path and causing interference, this embodiment's dual-sided collaborative polishing system employs an open synchronous belt drive mechanism (i.e., workpiece rotation drive module 5) as the C-axis drive for the workpiece 6. The C-axis refers to the rotation axis around the workpiece 6's rotation axis. The bottom of the workpiece 6 is coaxially and fixedly connected to the driven synchronous pulley 14. The motor 10 uses a high-precision servo motor connected to the active synchronous pulley 12, enabling precise transmission between the active synchronous pulley 12 and the driven synchronous pulley 14 fixed to the bottom of the workpiece 6 via the synchronous belt 13. This achieves "edge drive," reduces rotational inertia, and provides ample bottom or side feed space for inner surface machining.

[0035] To address the issue of radial runout during cantilever rotation of the workpiece 6, which is a deep-cavity, thin-walled rotating part, the double-sided co-polishing system of this embodiment incorporates an auxiliary support frame 9 at the top of the workpiece 6. This auxiliary support frame 9 employs a three-point or V-shaped structure to provide flexible support to the head of the workpiece 6. While allowing the workpiece 6 to rotate at high speed, the auxiliary support frame 9 effectively restricts its radial degree of freedom, forming a stable support system together with the driven synchronous pulley 14 at the bottom, effectively preventing chatter in the workpiece 6.

[0036] In some embodiments, the auxiliary support frame 9 may employ external roller contact support, with freely rotatable rollers arranged in a three-point or V-shape on the auxiliary support frame 9, the outer edge of which contacts the top outer wall of the workpiece 6 to form a contact radial constraint.

[0037] The central control module 4 is used to control the synchronous movement of the inner surface processing robot 1 and the outer surface processing robot 2, as well as the belt speed of the inner surface sanding and polishing assembly 7 and the outer surface sanding and polishing assembly 8, to complete the double-sided collaborative processing of the workpiece 6.

[0038] The central control module 4 includes a host computer computing unit, a main controller, and a communication network. The host computer computing unit is used to calculate the instantaneous linear velocity of the sanding belts of the inner surface sanding belt polishing assembly 7 and the outer surface sanding belt polishing assembly 8. The main controller is used to control the inner surface processing robot 1 and the outer surface processing robot 2 to perform synchronous trajectory movement and to receive the instantaneous linear velocity of the sanding belts calculated by the host computer computing unit. It also uses the communication network to independently adjust the sanding belt speeds of the inner surface sanding belt polishing assembly 7 and the outer surface sanding belt polishing assembly 8 in real time.

[0039] In this embodiment of the invention, the central control module 4 adopts a distributed control architecture based on EtherCAT real-time industrial Ethernet. The main controller, as the EtherCAT master station, is responsible for the high-precision motion interpolation synchronization of the two robots, ensuring trajectory space coordination; at the same time, based on the time-varying rotation speed generated by the host computer computing unit, it adjusts the belt speed of the servo motors in the inner surface sanding belt polishing component 7 and the outer surface sanding belt polishing component 8 in real time and independently through PDO communication, realizing the logical closed loop of dual-sided collaborative processing.

[0040] In some embodiments, the inner surface abrasive belt polishing assembly 7 and the outer surface abrasive belt polishing assembly 8 can be replaced with a computer-controlled small grinding head, an airbag polishing head, a magnetorheological polishing head, or an ultrasonic vibration-assisted grinding head.

[0041] like Figure 3 As shown, combined with Figures 1 to 2 This invention also provides a double-sided collaborative polishing method based on time-varying modulation of belt rotation speed, implemented using the aforementioned double-sided collaborative polishing system, comprising the following steps: S1: Based on the measuring equipment, full-diameter scanning of the inner and outer surfaces of the workpiece 6 is performed to obtain discrete point cloud data; the discrete point cloud data is mapped to a unified workpiece coordinate system through an interpolation algorithm to obtain the inner surface error matrix. and outer surface error matrix .

[0042] The workpiece coordinate system is based on the rotation axis of the workpiece 6. Axis establishment.

[0043] In some embodiments, a non-contact measuring device can be used to perform full-caliber scanning of the inner and outer surfaces of the workpiece 6 to be processed to obtain discrete point cloud data.

[0044] S2: In the workpiece coordinate system, design a full-diameter machining path shared by the inner surface machining robot 1 and the outer surface machining robot 2, and set the reference feed rate of both the inner surface machining robot 1 and the outer surface machining robot 2 to be... Calculate each discrete point on the machining path based on its length. Duration of stay .

[0045] Duration of stay The calculation formula is: (1); in, For the first on the processing path The arc length of the path element corresponding to each discrete point That is, the first The dwell time at each discrete point is the infinitesimal arc length of the path element at that point multiplied by the reference feed rate. The time required to sweep across. At each discrete point. The dwell time of the inner surface processing robot 1 Dwell time of outer surface processing robot 2 Forced to be identical, all set to .

[0046] In the workpiece coordinate system, a full-diameter machining path is generated, shared by the inner surface machining robot 1 and the outer surface machining robot 2. The two robots share the same motion time reference. Because the two robots must maintain spatial alignment to prevent collisions and ensure reference consistency, the dwell time of the inner surface machining robot 1 is... Dwell time of outer surface processing robot 2 It is a forced constant value, that is... .

[0047] The workpiece 6 to be processed is a rotating body. The function of the workpiece rotation drive module 5 in driving the workpiece 6 to rotate is to provide circumferential (i.e., C-axis) feed motion for processing. During processing, the inner surface processing robot 1 and the outer surface processing robot 2 are only responsible for carrying the inner surface abrasive belt polishing component 7 and the outer surface abrasive belt polishing component 8 along the generatrix direction (axial-radial profile, from the top to the bottom of the workpiece 6). The circumferential point-by-point sweeping of the surface is accomplished by the workpiece rotation drive module 5 driving the workpiece 6 to rotate around its rotation axis. The two are combined into a helical tool feed covering the entire surface. If the workpiece 6 does not rotate, the ends of the inner surface processing robot 1 and the outer surface processing robot 2 can only process along one generatrix to one meridian, and cannot cover the entire circumference. Especially for the inner surface of a deep cavity, due to the narrow space of the deep cavity, the slender cantilever of the inner surface processing robot 1 cannot make circumferential orbiting motion around the workpiece 6 inside the cavity. Therefore, full circumferential coverage can only be achieved by the rotation of the workpiece 6 itself. Furthermore, the rotation of the driven synchronous pulley 14, fixed to the bottom of the workpiece 6, reduces the moment of inertia and allows the inner and outer surfaces to be machined under the same rotational reference. In summary, the full-diameter machining path designed in step S2 is a curved path planned in the workpiece coordinate system. Its generatrix coordinates are given by the feeds of the inner surface machining robot 1 and the outer surface machining robot 2, and its circumferential coordinates are given by the rotation of the workpiece rotation drive module 5. The two work together to achieve full-diameter, dead-angle-free coverage of the inner and outer surfaces.

[0048] S3: Discrete points on the inner and outer surfaces of the workpiece 6. Target removal amount corresponding to surface error and Substitute these values ​​into the Preston equation to solve for the instantaneous linear velocities of the abrasive belts corresponding to the inner surface abrasive belt polishing component 7 and the outer surface abrasive belt polishing component 8.

[0049] The removal mechanism of the double-sided co-polishing method in this invention is based on the Preston equation, and combined with Hertzian contact theory to ensure the stability of the removal function.

[0050] The differential form of the Preston equation is: (2); in, The depth of material removal per unit time. This is a process factor (related to workpiece material and abrasive). Let be the normal contact pressure at the discrete point. The relative velocity between the polishing tool and the workpiece 6 at this discrete point.

[0051] Since the elastic contact wheel that contacts the workpiece 6 is made of elastic rubber, its contact with the hard and brittle workpiece 6 is elastic contact. The normal force is maintained in the active force control flange. Under constant conditions, the contact area is elliptical, and its semi-major axis... and semi-short axis Determined by the following formula: (3); (4); in, , The dimensionless coefficient of Hertzian elliptic contact (i.e., the contact elliptic coefficient) depends on the principal curvature distribution of the two elastic bodies at the contact point (i.e., the eccentricity of the contact ellipse), and can be determined by looking up tables in Hertzian contact theory. An auxiliary angle is introduced. ,make , , It is the relative curvature coefficient between the two principal planes at the contact point (determined by the principal curvature radius of the elastic contact wheel and the surface of the workpiece 6 at that point). , That is to be The coefficients are lookup table values ​​for the independent variable, when the contact area is circular ( )hour ; The equivalent radius of curvature, It is the equivalent elastic modulus.

[0052] From the above equation, it can be seen that in the normal force Under constant conditions, the area of ​​the removed region and internal pressure distribution, i.e., normal contact pressure This means that regardless of subsequent adjustments to the abrasive belt speed, the spatial resolution of the removal function remains constant, preventing any unintended edge removal effects. The elastic contact wheels, machined on both the inner and outer surfaces, apply similar but opposite normal contact pressures along the same normal direction to the surface of the workpiece 6. This creates a force balance, and at the same time, the auxiliary support frame 9 restricts the radial degree of freedom of the workpiece 6 to be processed, so as to suppress the stress deformation and chatter of the workpiece 6 with deep cavity and thin wall characteristics during the processing.

[0053] Due to relative velocity Approximately equal to the linear velocity of the sanding belt Then the removal function per unit time for: (5); For the first on the processing path Let there be discrete points, and their dwell time be . Then the total amount removed at that point for: (6); in, The target error removal amount, The contact center pressure is usually a constant. This is the process coefficient. The instantaneous linear velocity of the sand belt.

[0054] It should be noted that: length of stay The method for determining this is as follows: In traditional residence time control, the linear velocity of the sand belt is constant. These are the design variables derived from the inverse solution of this formula to achieve the target removal amount (i.e., Different dwell times are achieved by changing the feed rate point by point. In this invention, because the inner surface machining robot 1 and the outer surface machining robot 2 must maintain spatial alignment to prevent collisions and ensure a unified reference, their feed rates are locked to the same reference feed rate. Since it cannot be changed independently on each side, the residence time is no longer used as a control variable, but degenerates into a kinematic constant determined solely by the path geometry and feed rate: The first... The dwell time at a discrete point is equal to the arc length of the infinitesimal element of the path at that point. was with The time required to sweep, i.e. Furthermore, since the inner surface processing robot 1 and the outer surface processing robot 2 share the same path and the same time reference, the dwell time of the inner surface processing robot 1 is... Dwell time of outer surface processing robot 2 Forced sameness, i.e. . Since the quantity has been determined as a known quantity by the above formula, only the quantity remaining in formula (6) is... One variable to be determined can be solved by setting the total removal amount of the inner and outer surfaces of the workpiece 6 to be equal to the error at that point, as detailed in equations (7) and (8). This is precisely the essence of the present invention: replacing dwell time modulation with belt speed modulation. Locked at a kinematic constant, the linear velocity of the sanding belt is then independently adjustable on each surface. This is to compensate for the difference in the amount of material removed from the inner and outer surfaces of the workpiece 6. To resolve the above contradiction, this embodiment of the invention uses equation (6) for reverse solution to calculate the instantaneous linear velocity of the abrasive belt of the inner surface abrasive belt polishing assembly 7. and the instantaneous linear velocity of the abrasive belt in the outer surface abrasive belt polishing component 8 This achieves physical decoupling of the amount of material removed.

[0055] Target removal amount of the inner surface at this discrete point The inner surface error at that point Substituting it into equation (6), the instantaneous linear velocity of the inner surface abrasive belt polishing component 7 is obtained by inverse solving. for: (7); Similarly, the target removal amount at this discrete point on the outer surface The outer surface error at that point Substituting it into equation (6), the instantaneous linear velocity of the abrasive belt of the outer surface abrasive belt polishing component 8 is obtained by inverse solution. for: (8).

[0056] S4: Generate executable synchronous motion control files for inner surface machining robot 1 and outer surface machining robot 2 based on the machining path, and generate executable abrasive belt speed control files for inner surface abrasive belt polishing component 7 and outer surface abrasive belt polishing component 8 based on the instantaneous linear velocity of the abrasive belt, thus completing the double-sided collaborative polishing process.

[0057] The instantaneous linear velocity of the abrasive belt calculated by equations (7) and (8) is converted into the angular velocity command of the servo motors in the inner surface abrasive belt polishing component 7 and the outer surface abrasive belt polishing component 8, generating a four-dimensional process file containing position, feed speed, inner surface abrasive belt speed and outer surface abrasive belt speed.

[0058] Under the scheduling of central control module 4, double-sided collaborative processing is initiated: Synchronous motion control: The main controller drives the dual robots and the C-axis of the workpiece 6 to perform high-precision interpolation motion via the EtherCAT bus, ensuring that the elastic contact wheels in the inner surface sanding belt polishing assembly 7 and the outer surface sanding belt polishing assembly 8 are always located in the same normal direction on the surface of the workpiece 6.

[0059] Time-varying speed control: The main controller reads the corresponding speed command based on the real-time feedback of the path positions of the inner surface processing robot 1 and the outer surface processing robot 2, and writes it into the servo motors in the inner surface sanding belt polishing assembly 7 and the outer surface sanding belt polishing assembly 8 in real time through PDO communication.

[0060] The double-sided collaborative polishing method of this invention linearly compensates for the loss of feed speed adjustment freedom due to collaborative motion by time-varying the belt rotation speed, thus ensuring the independent convergence of double-sided errors.

[0061] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0062] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A double-sided collaborative polishing system based on time-varying modulation of belt rotation speed, characterized in that, include: The inner surface processing robot (1), the outer surface processing robot (2), the workpiece support platform (3), the central control module (4) and the workpiece rotation drive module (5); An inner surface sanding belt polishing assembly (7) is fixedly installed on the end effector of the inner surface machining robot (1); an outer surface sanding belt polishing assembly (8) is fixedly installed on the end effector of the outer surface machining robot (2); The workpiece rotation drive module (5) is fixedly installed on the workpiece support platform (3) to fix the workpiece (6) to be processed and drive it to rotate; The central control module (4) is used to control the synchronous movement of the inner surface processing robot (1) and the outer surface processing robot (2) and to control the belt speed of the inner surface sanding belt polishing assembly (7) and the outer surface sanding belt polishing assembly (8) to complete the double-sided collaborative processing of the workpiece (6); The central control module (4) includes a host computer computing unit, a main controller, and a communication network; The host computer computing unit is used to calculate the instantaneous linear velocity of the sand belt of the inner surface sanding belt polishing assembly (7) and the outer surface sanding belt polishing assembly (8); the main controller is used to control the inner surface processing robot (1) and the outer surface processing robot (2) to perform synchronous trajectory motion and receive the instantaneous linear velocity of the sand belt calculated by the host computer computing unit, and adjust the sand belt speed of the inner surface sanding belt polishing assembly (7) and the outer surface sanding belt polishing assembly (8) independently in real time through the communication network; Instantaneous linear velocity of the inner surface abrasive belt polishing assembly (7) and the instantaneous linear velocity of the abrasive belt in the outer surface abrasive belt polishing assembly (8) The calculation formula is: ； ； in, and Each discrete point on the inner and outer surfaces of the workpiece (6) to be processed is respectively The amount of target material removed corresponding to the surface error. For each discrete point on the processing path The length of stay at the place, This is the process coefficient. This represents the pressure at the contact center.

2. The double-sided collaborative polishing system based on time-varying belt rotation speed modulation according to claim 1, characterized in that, Both the inner surface processing robot (1) and the outer surface processing robot (2) are six-degree-of-freedom robotic arms.

3. The double-sided collaborative polishing system based on time-varying belt rotation speed modulation according to claim 1, characterized in that, The workpiece rotation drive module (5) includes an auxiliary support frame (9), a motor (10), a main support plate (11), an active synchronous pulley (12), a synchronous belt (13), and a driven synchronous pulley (14); Among them, the auxiliary support frame (9) and the main support plate (11) are both fixed on the workpiece support platform (3); the motor (10) is fixed on one side of the main support plate (11), and the active synchronous pulley (12) and the driven synchronous pulley (14) are located on the other side of the main support plate (11); the output shaft of the motor (10) is connected to the active synchronous pulley (12), the driven synchronous pulley (14) is rotatably connected to the main support plate (11), and the synchronous belt (13) is tensioned on the driven synchronous pulley (14) and the active synchronous pulley (12); the bottom of the workpiece (6) is fixedly connected to the side of the driven synchronous pulley (14) through a flange, and the top of the workpiece (6) is placed on the auxiliary support frame (9) to limit the radial degree of freedom of the workpiece (6) and prevent its chatter.

4. The double-sided collaborative polishing system based on time-varying belt rotation speed modulation according to claim 3, characterized in that, The auxiliary support frame (9) is supported by external rollers. Rollers that can rotate freely are arranged in a three-point or V-shape on the auxiliary support frame (9). The outer edge of the rollers contacts the top outer wall of the workpiece (6) to form a contact radial constraint.

5. The double-sided collaborative polishing system based on time-varying belt rotation speed modulation according to claim 1, characterized in that, Both the inner surface sanding belt polishing assembly (7) and the outer surface sanding belt polishing assembly (8) include a servo motor, a drive wheel driven by the servo motor, an elastic contact wheel that contacts the workpiece (6), a sanding belt tensioned between the drive wheel and the elastic contact wheel, and a drive force control flange. The elastic contact wheel presses the working section of the sanding belt against the surface of the workpiece (6). The inner surface sanding belt polishing assembly (7) and the outer surface sanding belt polishing assembly (8) sense the normal contact force in real time through the drive force control flange and maintain a constant contact center pressure through closed-loop control. The instantaneous linear velocity of the sanding belt is the surface linear velocity of the working section of the sanding belt along its running direction, which is independently driven by the servo motor through the drive wheel and responds to the sanding belt speed command of the central control module (4).

6. The double-sided collaborative polishing system based on time-varying belt rotation speed modulation according to claim 1, characterized in that, The workpiece to be processed (6) is a fairing, an aircraft engine nozzle, a ceramic antenna cover, or a deep-sea pressure-resistant glass cover.

7. A double-sided collaborative polishing method based on time-varying modulation of belt rotation speed, implemented using the double-sided collaborative polishing system according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Based on the measurement equipment, full-diameter scanning of the inner and outer surfaces of the workpiece (6) is performed to obtain discrete point cloud data; the discrete point cloud data is mapped to a unified workpiece coordinate system through an interpolation algorithm to obtain the inner surface error matrix. and outer surface error matrix ; S2: In the workpiece coordinate system, design a full-diameter machining path shared by the inner surface machining robot (1) and the outer surface machining robot (2), and set the reference feed rate of both the inner surface machining robot (1) and the outer surface machining robot (2) to be... Calculate each discrete point on the machining path based on its length. Duration of stay ; S3: Discrete each point on the inner and outer surfaces of the workpiece (6) Target removal amount corresponding to surface error and Substitute them into the Preston equation to solve for the instantaneous linear velocity of the abrasive belt corresponding to the inner surface abrasive belt polishing component (7) and the outer surface abrasive belt polishing component (8); Instantaneous linear velocity of the inner surface abrasive belt polishing assembly (7) and the instantaneous linear velocity of the abrasive belt in the outer surface abrasive belt polishing assembly (8) The calculation formula is: ； ； in, This is the process coefficient. This refers to the pressure at the center of contact. S4: Generate executable synchronous motion control files for the inner surface processing robot (1) and the outer surface processing robot (2) based on the processing path, and generate executable sand belt speed control files for the inner surface sand belt polishing component (7) and the outer surface sand belt polishing component (8) based on the instantaneous linear velocity of the sand belt, to complete the double-sided collaborative polishing process.

8. The double-sided collaborative polishing method based on time-varying belt rotation speed modulation according to claim 7, characterized in that, In step S2, the dwell time The calculation formula is: ； in, For the first on the processing path The arc length of the path element corresponding to each discrete point; At each discrete point Dwell time of the inner surface processing robot (1) Dwell time of the external surface processing robot (2) Because they share the same machining path and the same baseline feed rate, they are forced to be identical and are all set to the same value. .

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