A self-adaptive pressure and rotating speed control method for multi-head cooperative polishing

Abstract

The application discloses a kind of self-adapting pressure and rotating speed control methods of multiple polishing head coordination polishing, belong to industrial automation control and polishing processing technical field.The method includes: the normal force, rotating speed, driving torque, vibration response, contact temperature and axial displacement data of each polishing head are collected;Identify the contact mechanical impedance between each polishing head and workpiece;Determine the equivalent removal energy input density of each polishing head based on the above parameters;Establish spatial removal superposition matrix;According to the deviation from target energy field, determine the target removal energy distribution of each polishing head;Then, according to the change of contact mechanical impedance, temperature rise state and vibration state, make correction;Finally, under the constraint of corrected distribution, generate the target pressure and target rotating speed of each polishing head.The application unifies pressure and rotating speed into equivalent removal energy constraint, realizes multiple polishing head coordination control, can distinguish different contact conditions, reduces the risk of heat concentration and vibration superposition, improves polishing consistency and stability.

Description

Technical Field

[0001] This invention relates to the field of industrial automation control and polishing technology, and in particular to an adaptive pressure and speed control method for multi-head collaborative polishing. Background Technology

[0002] In polishing large workpieces or high-precision functional surfaces, multiple polishing heads are often used simultaneously on the same workpiece surface to improve processing efficiency. Existing multi-head polishing equipment typically performs independent pressure closed-loop control or speed closed-loop control on each grinding head, treating each grinding head as an independent execution unit.

[0003] However, when multiple grinding heads simultaneously contact the same workpiece, strong coupling occurs between them through the workpiece, fixture, support platform, polishing pad, and polishing fluid film. Changes in the pressure or rotational speed of any grinding head not only affect its own removal state but may also alter the contact stiffness, friction state, temperature rise, and vibration response of adjacent grinding heads. Consequently, the removal contributions of multiple grinding heads on the workpiece surface may become cumulatively mismatched, leading to problems such as localized over-polishing, localized under-polishing, edge collapse, concentrated hot spots, or surface ripples.

[0004] Existing independent pressure control or independent speed control methods mainly focus on the local state of a single grinding head, and their control parameters (such as PID gain, pressure threshold, and speed limit) are usually preset and fixed. They lack the ability to adaptively adjust to changes in workpiece material, grinding head wear, fluctuations in polishing fluid performance, and abrupt changes in contact conditions (such as hard contact, contact loss, hot spot formation, and vibration superposition). When the operating conditions change, fixed-parameter controllers cannot automatically adjust the control strategy and tend to treat all machining errors as ordinary pressure errors, leading to misadjustment, overadjustment, or response lag.

[0005] Therefore, an adaptive multi-grinding head collaborative control method is needed. This method can identify the mechanical impedance of the grinding head-workpiece contact online and automatically adjust the pressure and speed distribution of each grinding head according to changes in the contact state. Simultaneously, it achieves adaptive equilibrium of the global removal energy field through spatial removal of the superposition matrix. Based on the above adaptive control concept, this invention proposes an adaptive pressure and speed control method for multi-grinding head collaborative polishing to overcome the shortcomings of existing fixed-parameter control strategies under complex coupled conditions. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an adaptive pressure and speed control method for multi-head collaborative polishing. It aims to solve the problems in the prior art where multi-head polishing equipment treats each grinding head as an independent control object, which easily leads to contact coupling, concentrated frictional heat, and superposition of vibrations when multiple grinding heads act on the same workpiece surface at the same time.

[0007] To achieve the above-mentioned objectives, the first aspect of this invention proposes an adaptive pressure and speed control method for multi-head collaborative polishing, comprising the following steps: S1, collect data on normal force, rotational speed, driving torque, vibration response, contact temperature and axial displacement of at least three polishing heads during the polishing process; S2, based on the normal force, the vibration response, the contact temperature, and the axial displacement data, identify the contact mechanical resistance between each polishing head and the workpiece; S3, based on the normal force, rotational speed, driving torque, contact area and contact mechanical resistance of each polishing head, determine the equivalent removal energy input density of each polishing head; S4. Based on the removal contribution relationship of each polishing head to different areas of the workpiece surface, a spatial removal superposition matrix is ​​established, and based on the spatial removal superposition matrix and the equivalent removal energy input density of each, the actual equivalent removal energy field of the workpiece surface is determined. S5, determine the target removal energy allocation amount corresponding to each polishing head based on the deviation between the target equivalent removal energy field and the actual equivalent removal energy field; S6. Based on the changes in contact mechanical resistance, temperature rise, and vibration of each polishing head, the target energy removal distribution is corrected to obtain the corrected target energy removal distribution for each polishing head. S7, under the constraint of the corrected target removal energy distribution, the target pressure and target speed of each polishing head are generated in a coordinated manner, so that the pressure adjustment and speed adjustment of each polishing head are jointly constrained by the target equivalent removal energy field.

[0008] Optionally, the contact mechanical impedance includes a contact stiffness component, a damping component, and a phase lag component; wherein, the contact stiffness component is determined based on the change in normal force and the change in axial displacement, the damping component is determined based on the relationship between the vibration velocity response and the force response, and the phase lag component is determined based on the phase difference between the periodic disturbance signal of the main shaft and the normal force fluctuation signal.

[0009] Optionally, the equivalent energy input density is determined based on the normal force, rotational speed, effective friction radius, contact area, friction state coefficient, and contact stability coefficient; wherein the friction state coefficient is determined based on the driving torque, normal force, and effective friction radius, and the contact stability coefficient is corrected based on the contact mechanical impedance, vibration energy, and temperature rise rate.

[0010] Optionally, the workpiece area to be polished is divided into multiple grid areas. Each element in the spatial removal superposition matrix represents the removal contribution coefficient of each polishing head to each grid area. The actual equivalent removal energy input density of each grid area is obtained by multiplying the equivalent removal energy input density of each polishing head by the corresponding removal contribution coefficient and then superimposing them.

[0011] Optionally, the spatial removal superposition matrix is ​​determined based on at least two parameters among the grinding head diameter, polishing pad compression characteristics, grinding head motion trajectory, grinding head spacing, and workpiece feed speed.

[0012] Optionally, in step S6, the removal requirement is first determined based on the deviation between the target equivalent removal energy field and the actual equivalent removal energy field, and then the removal requirement is allocated according to the contact stability margin of each polishing head. When the change in contact mechanical resistance of a certain polishing head increases, the temperature rise rate increases, or the vibration energy increases, the target removal energy allocation corresponding to that polishing head is reduced, and the reduced target removal energy allocation is transferred to other polishing heads that have overlapping removal areas with that polishing head and whose contact stability conditions meet the threshold according to the contact stability margin.

[0013] Optionally, in step S7, when a certain polishing head requires an increased removal amount in a corresponding area and the polishing head is in a stable contact state, the target pressure and target rotation speed of the polishing head are allowed to increase synergistically within a preset constraint range; when the temperature rise rate or vibration energy of the polishing head approaches the corresponding threshold, the target pressure and target rotation speed of the polishing head are restricted from increasing simultaneously, and the equivalent removal energy consistency of the workpiece surface is maintained by at least one of reducing the target pressure, adjusting the target rotation speed, or transferring the target removal energy distribution.

[0014] Optionally, when any polishing head reduces its target removal energy allocation due to increased temperature rise rate, increased vibration energy, sudden change in contact stiffness, or actuator saturation, a set of neighboring polishing heads is selected according to the spatial removal superposition matrix, and the reduced target removal energy allocation of the polishing head is redistributed according to the contact stability margin of each polishing head in the set of neighboring polishing heads; the polishing heads in the set of neighboring polishing heads have overlapping removal areas with the polishing head on the workpiece surface, and their contact mechanical resistance change, temperature rise rate, and vibration energy are all within the corresponding threshold range.

[0015] Optionally, the dominant frequency and phase are extracted based on the vibration response of each polishing head; when the dominant frequency difference between adjacent polishing heads is less than a preset frequency difference threshold and the phase difference is less than a preset phase threshold, a rotational speed offset is applied to at least one adjacent polishing head to make the periodic disturbance phases of the adjacent polishing heads staggered; wherein, the rotational speed offset is 1% to 3% of the target rotational speed, and when the rotational speed offset is applied, the equivalent removal energy input density of the corresponding region is kept within the target range by synchronously adjusting the target pressure.

[0016] Optionally, at least one of the temperature threshold, vibration threshold, and contact stiffness mutation threshold is dynamically updated based on historical data and current contact mechanical impedance within a stable processing window; when the distance from the center of the polishing head to the edge of the workpiece is less than 1.2 times the radius of the polishing head, the edge control mode is entered. In the edge control mode, the contact area is corrected according to the actual overlap area between the polishing head and the workpiece, the target energy removal distribution of the corresponding polishing head is reduced, and the target pressure of the corresponding polishing head is limited.

[0017] The beneficial effects of this invention are: 1. The adaptive pressure and speed control method for multi-head collaborative polishing of the present invention collects data on the normal force, speed, driving torque, vibration response, contact temperature, and axial displacement of each polishing head, and identifies the contact mechanical impedance between each polishing head and the workpiece. This expands the control object from the pressure or speed state of a single polishing head to the contact state between the polishing head and the workpiece. Therefore, the controller can distinguish between different working conditions such as normal load changes, hard contact, contact loss, hot spot formation, and vibration superposition, reducing misadjustments caused by treating all processing errors as ordinary pressure errors. The normal force, speed, driving torque, contact area, and contact mechanical impedance of each polishing head are uniformly mapped to an equivalent removal energy input density, so that pressure and speed regulation are no longer independent control quantities, but are generated collaboratively under the same equivalent removal energy constraint. Therefore, when it is necessary to increase the removal amount, pressure increase, speed adjustment, or neighborhood compensation can be selected according to the contact stability state, rather than simply increasing pressure and speed simultaneously, thereby reducing the risk of frictional heat concentration and vibration energy superposition.

[0018] 2. The adaptive pressure and speed control method for multi-head collaborative polishing of the present invention describes the removal contribution relationship of each polishing head to different areas of the workpiece surface through a spatial removal superposition matrix, and determines the actual equivalent removal energy field of the workpiece surface based on this spatial removal superposition matrix. This transforms the control objective from the local stability of multiple isolated polishing heads to the global equivalent removal energy field stability of the same workpiece surface. Therefore, it helps to reduce the risks of local over-polishing, local under-polishing, and amplification of surface shape errors.

[0019] 3. The adaptive pressure and speed control method for multi-head collaborative polishing of the present invention determines the target removal energy allocation for each polishing head based on the deviation between the target equivalent removal energy field and the actual equivalent removal energy field, and makes corrections based on changes in contact mechanical impedance, temperature rise, and vibration. When a certain polishing head experiences an increase in temperature rise rate, increased vibration energy, a sudden change in contact stiffness, or actuator saturation, the reduced target removal energy allocation for that polishing head can be transferred to other polishing heads that meet the contact stability conditions, thereby maintaining overall removal consistency even in the event of local anomalies.

[0020] 4. The adaptive pressure and speed control method for multi-head collaborative polishing of the present invention, through a vibration phase staggering mechanism, applies a speed offset when the main vibration frequencies and phases of adjacent polishing heads are close, and simultaneously adjusts the pressure, so that the periodic disturbance phases of adjacent polishing heads are staggered. This reduces the risk of surface ripples or resonance amplification caused by multiple polishing heads superimposing on the same frequency band and phase.

[0021] 5. The adaptive pressure and speed control method for multi-head collaborative polishing of the present invention, through an adaptive threshold mechanism, enables the temperature threshold, vibration threshold and contact stiffness mutation threshold to be dynamically updated based on historical data and current contact mechanical impedance within a stable processing window, avoiding the problem of insufficient adaptability of fixed thresholds under different materials, different polishing fluid states, different grinding head wear stages and different contact stiffness states.

[0022] 6. The adaptive pressure and speed control method for multi-head collaborative polishing of the present invention, in edge control mode, corrects the contact area according to the actual overlap area between the polishing head and the workpiece, and reduces the target removal energy distribution and target pressure of the corresponding polishing head, which can reduce the increase in unit area pressure caused by the reduction of edge contact area, thereby reducing the risk of edge collapse. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the adaptive pressure and speed control method for multi-head collaborative polishing of the present invention. Figure 2 This is a block diagram of the controller for the adaptive pressure and speed control method of multi-head collaborative polishing according to the present invention. Figure 3 This is a block diagram of the multi-source state sensing module of the adaptive pressure and speed control method for multi-head collaborative polishing of the present invention. Figure 4 This is a block diagram of the contact mechanical impedance identification module in the adaptive pressure and speed control method for multi-head collaborative polishing of the present invention. Figure 5 This is a block diagram of the equivalent removal energy field calculation module for the adaptive pressure and speed control method of multi-head collaborative polishing of the present invention.

[0024] Explanation of reference numerals in the attached figures: 1. Multi-head collaborative polishing equipment; 2. Workpiece; 10. Multi-head execution module; 11. First grinding head; 12. Second grinding head; 13. Third grinding head; 14. nth grinding head; 20. Pressure loading mechanism; 30. Servo spindle; 31. Spindle motor; 32. Spindle sleeve; 33. Spindle encoder; 40. Polishing disc; 41. Polishing disc backplate; 42. Polishing pad; 43. Polishing liquid film; 50. Multi-source state sensing module; 51. Normal force sensor; 52. Spindle torque sensor; 53. Triaxial vibration sensor; 54. Contact temperature sensor; 55. 56. Displacement sensor; 60. Polishing fluid flow sensor; 61. Controller; 62. Data acquisition interface; 63. Real-time computing unit; 74. Execution command output interface; 75. Contact mechanical impedance identification module; 76. Contact stiffness calculation unit; 77. Damping calculation unit; 78. Phase lag calculation unit; 89. Equivalent removal energy field calculation module; 80. Equivalent removal energy density calculation unit; 81. Spatial removal superposition matrix unit; 82. Target energy field comparison unit; 93. Cooperative pressure-speed control module; 100. Abnormal working condition protection module.

[0025] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] Reference Figures 1-5 This embodiment provides an adaptive pressure and speed control method for multi-head collaborative polishing, which can be executed by the controller 60 in the multi-head collaborative polishing device 1. The multi-head collaborative polishing device 1 includes a multi-head execution module 10, a multi-source state sensing module 50, a contact mechanical impedance identification module 70, an equivalent removal energy field calculation module 80, a collaborative pressure-speed control module 90, an abnormal working condition protection module 100, and a controller 60.

[0029] This invention adopts an adaptive control architecture. The controller can automatically correct the target removal energy distribution of each polishing head based on the real-time identified contact mechanical impedance, temperature rise rate and vibration energy, and dynamically adjust the cooperative generation rules of pressure and speed, so that the control system can maintain stable removal consistency under different materials, different wear stages and different processing environments.

[0030] The multi-head polishing module 10 includes at least three polishing heads, such as a first polishing head 11, a second polishing head 12, a third polishing head 13 to an nth polishing head 14, where n is an integer greater than or equal to 4. Each polishing head includes a pressure loading mechanism 20, a servo spindle 30, and a polishing disc 40. The pressure loading mechanism 20 is used to apply a normal load to the polishing disc 40, and the pressure loading mechanism 20 can be an electric cylinder, a pneumatic-hydraulic servo cylinder, or a voice coil linear actuator. The servo spindle 30 includes a spindle motor 31, a spindle sleeve 32, and a spindle encoder 33. The spindle motor 31 is used to drive the polishing disc 40 to rotate, and the spindle encoder 33 is used to detect the rotational speed of the corresponding polishing head. The polishing disc 40 includes a polishing disc backplate 41 and a polishing pad 42, and a polishing liquid film 43 is formed between the polishing pad 42 and the workpiece 2.

[0031] The multi-source state sensing module 50 includes a normal force sensor 51, a spindle torque sensor 52, a triaxial vibration sensor 53, a contact temperature sensor 54, and a displacement sensor 55. The normal force sensor 51 is used to acquire the normal force of the corresponding polishing head; the spindle torque sensor 52 is used to acquire the drive torque of the servo spindle 30; the triaxial vibration sensor 53 is used to acquire the vibration response of the polishing head; the contact temperature sensor 54 is used to acquire the temperature near the polishing contact area; and the displacement sensor 55 is used to acquire the axial displacement of the polishing head. Furthermore, the multi-source state sensing module 50 may also include a polishing fluid flow sensor 56 for acquiring the polishing fluid supply status.

[0032] The controller 60 includes a data acquisition interface 61, a real-time computing unit 62, and an execution command output interface 63. The data acquisition interface 61 receives data on normal force, rotational speed, drive torque, vibration response, contact temperature, and axial displacement. The real-time computing unit 62 is used to perform contact mechanical impedance identification, equivalent removal energy input density calculation, spatial removal superposition matrix calculation, target removal energy distribution, target pressure generation, and target rotational speed generation. The execution command output interface 63 is used to output control commands to the pressure loading mechanism 20 and the servo spindle 30.

[0033] Let the number of polishing heads be N, and the normal force of the i-th polishing head be F. i angular velocity is ω i The driving torque is T i The contact temperature is θ i The axial displacement is x i The vibration response is ai , where i = 1, 2, ..., N.

[0034] The contact mechanical impedance identification module 70 identifies the contact mechanical impedance Z between the i-th polishing head and the workpiece 2 based on normal force, vibration response, contact temperature, and axial displacement data. i The contact mechanical resistance Z i At least the contact stiffness component K i Damping component C i and phase lag component φ i .

[0035] Contact stiffness calculation unit 71 determines the contact stiffness component K based on the change in normal force and the change in axial displacement. i For example, the change in normal force ΔF can be used within a sampling window. i With axial displacement change Δx i The ratio determines K i Furthermore, the effects of random noise are reduced through filtering or moving average.

[0036] Damping calculation unit 72 determines the damping component C based on the relationship between vibration velocity response and force response. i Specifically, the vibration velocity response can be calculated from the vibration response, and the amplitude and phase relationship between the force response and the velocity response can be determined by combining the corresponding normal force wave signal, thereby obtaining the damping component C. i .

[0037] Phase lag calculation unit 73 determines the phase lag component φ based on the phase difference between the spindle periodic disturbance signal and the normal force fluctuation signal. i The spindle periodic disturbance signal can be obtained from the angular position signal, speed fluctuation signal, or the main frequency component in the vibration response of the spindle encoder 33.

[0038] When K i When the temperature rises and the rate of temperature rise increases, the controller 60 determines that the corresponding polishing head may enter a hard contact or local high friction state; when K i Decrease and F i When the fluctuation increases, the controller 60 determines that the corresponding polishing head may have insufficient contact, excessive liquid film, or local collapse of the polishing pad 42; when the main vibration frequency and phase of adjacent polishing heads are close, the controller 60 determines that there is a risk of vibration superposition.

[0039] The equivalent removal energy density calculation unit 81 converts the pressure, rotation speed and contact state of each polishing head into the equivalent removal energy input density.

[0040] The equivalent energy input density is determined based on the normal force, rotational speed, effective friction radius, contact area, friction state coefficient, and contact stability coefficient; among which, the friction state coefficient is determined based on the driving torque, normal force, and effective friction radius, and the contact stability coefficient is corrected based on the contact mechanical impedance, vibration energy, and temperature rise rate.

[0041] Specifically, the equivalent removal energy input density E of the i-th polishing head i Determined according to the following relationship: E i =μ i ·F i ·R i ·ω i ·ξ i / A i ; Among them, F i R is the normal force of the i-th polishing head. i For the effective friction radius, ω i Let A be the angular velocity. i For the contact area, μ i Let ξ be the friction state coefficient. i This is the contact stability coefficient.

[0042] Friction state coefficient μ i According to the driving torque T i Normal force F i and effective friction radius R i Determined. For example, it can be determined based on T. i / (F i ·R i Estimate μ i This is further corrected by considering the polishing fluid flow rate and contact temperature. Contact stability coefficient ξ i Based on the contact mechanical resistance Z i Corrections for vibration energy and temperature rise rate. When the temperature rise rate increases, the vibration energy increases, or the change in contact mechanical resistance exceeds the corresponding threshold, ξ... i The value is reduced to characterize the decrease in the stable removal capability of the polishing head.

[0043] Contact area A i Determined based on the actual contact range between the polishing head and workpiece 2. Within the internal region of workpiece 2, A... i It can be determined based on the contact geometry and compression state of the polishing pad 42; in the edge region of the workpiece 2, Ai is corrected based on the actual overlap area between the polishing head and the workpiece 2.

[0044] The workpiece to be polished area is divided into multiple grid areas. Each element in the spatial removal superposition matrix represents the removal contribution coefficient of each polishing head to each grid area. The actual equivalent removal energy input density of each grid area is obtained by multiplying the equivalent removal energy input density of each polishing head by the corresponding removal contribution coefficient and then superimposing them.

[0045] Specifically, the spatial removal overlay matrix unit 82 divides the polishing area of ​​workpiece 2 into m grid regions and establishes a spatial removal overlay matrix H. Hgi represents the removal contribution coefficient of the i-th polishing head to the g-th grid region, where g = 1, 2, ..., m, i = 1, 2, ..., n; The spatial removal superposition matrix H can be determined based on at least two parameters among the following: grinding head diameter, polishing pad 42 compression characteristics, grinding head motion trajectory, grinding head spacing, and workpiece 2 feed speed. For the same grid region, if the removal regions of multiple polishing grinding heads overlap, the actual equivalent removal energy input density of that grid region is obtained by superimposing the equivalent removal energy input densities of the multiple polishing grinding heads. The actual equivalent energy input density removed from the g-th grid region Determined according to the following relationship: = .

[0046] In this way, the controller 60 can obtain the actual equivalent energy field removed from the surface of the workpiece 2. If a certain region E g A value lower than the target equivalent removal energy input density indicates a tendency for insufficient removal in that region; if a certain region E g An energy input density higher than the target equivalent removal density indicates an over-removal trend in the region.

[0047] The target energy field comparison unit 83 compares the target equivalent removal energy field with the actual equivalent removal energy field to obtain the energy deviation of each grid region. The controller 60 maps the energy deviation to the corresponding polishing head according to the spatial removal superposition matrix H to determine the target removal energy allocation of each polishing head.

[0048] The stability margin generation unit determines the contact stability margin M based on the changes in contact mechanical resistance, temperature rise, and vibration of each polishing head. i Contact stability margin M i This is used to characterize the ability of the i-th polishing head to handle the target energy removal within the current control cycle. Specifically, when the change in contact mechanical resistance of the i-th polishing head is small, the temperature rise rate is low, and the vibration energy is low, its contact stability margin M is... i The contact stability margin M is relatively high; when the change in contact mechanical resistance increases, the rate of temperature rise increases, or the vibration energy increases, the contact stability margin M decreases. i reduce.

[0049] In step S6, the controller 60 determines the contact stability margin M. i The target removal energy allocation is adjusted. For polishing heads with low contact stability margins, their target removal energy allocation is reduced; for other polishing heads that meet the contact stability conditions and have a removal contribution relationship with the target area, the proportion of target removal energy they can handle is increased. This yields the adjusted target removal energy allocation for each polishing head.

[0050] The pressure target generation unit and the rotation speed target generation unit generate the target pressure F of the i-th polishing head based on the energy distribution amount removed from the corrected target. i and target angular velocity ω i Among them, the target pressure F i This refers to the target normal load or the corresponding pressure loading control quantity.

[0051] When the area corresponding to the i-th polishing head requires increased removal and the polishing head is in a stable contact state, the controller 60 allows the target pressure F. i and target angular velocity ω i The system works collaboratively within preset constraints. When the temperature rise rate or vibration energy of the polishing head approaches a corresponding threshold, the controller 60 limits the target pressure F. i and target angular velocity ω i Simultaneously, the equivalent removal energy input density of the corresponding region is maintained by at least one of the following methods: reducing target pressure, fine-tuning target rotation speed, or shifting the target removal energy distribution.

[0052] In one implementation, the target pressure F i It can be generated based on factors such as removal error, contact stability margin, change in contact mechanical resistance, temperature rise rate, and vibration energy, and is limited to the minimum allowable pressure F. min and maximum permissible pressure F max between.

[0053] In one implementation, the target angular velocity ω i It can be generated based on the following relationship: ω i =Clamp[E i ,target·A i / (μ i ·F i ·R i ·ξ i ), ω min ω max ]; Among them, E i ,target is the equivalent energy input density for the current removal task of the i-th polishing head, ωmin and ω max These represent the minimum and maximum permissible angular velocities, respectively, and Clamp represents the amplitude limiting function.

[0054] Therefore, pressure and rotational speed are constrained within the same equivalent energy removal input relationship. When pressure increases, rotational speed does not necessarily need to increase synchronously; when rotational speed increases, the target pressure can be limited based on contact mechanical resistance, temperature rise, and vibration conditions, thereby reducing the risk of heat concentration and vibration superposition.

[0055] When any polishing head reduces its target removal energy allocation due to increased temperature rise rate, increased vibration energy, sudden change in contact stiffness, or actuator saturation, the neighborhood compensation unit selects a set of neighboring polishing heads based on the spatial removal superposition matrix H. The polishing heads in this set of neighboring heads satisfy the following conditions: they overlap with the removal area on the surface of workpiece 2; the change in contact mechanical resistance is within the corresponding threshold range; the temperature rise rate is within the corresponding threshold range; and the vibration energy is within the corresponding threshold range.

[0056] The controller 60 redistributes the target energy removal amount reduced by the polishing head according to the contact stability margin of each polishing head in the adjacent head set. The adjacent head with a higher contact stability margin bears a larger compensation proportion; the adjacent head with a lower contact stability margin or close to the abnormal threshold bears no or less compensation removal amount. In this way, the equivalent energy removal consistency of the workpiece 2 surface can still be maintained even when there is a local grinding head abnormality.

[0057] In one specific embodiment, when the main oscillation frequencies of the first grinding head 11 and the second grinding head 12 are close and the phase difference is less than 30°, the controller 60 applies a 1% to 3% rotational speed offset to the second grinding head 12 and synchronously adjusts the target pressure of the second grinding head 12 to avoid the periodic disturbances of the two grinding heads from superimposing in the same area.

[0058] The abnormal operating condition protection module 100 sets temperature threshold, vibration threshold, and contact stiffness mutation threshold. At least one of the above thresholds is dynamically updated based on historical data and current contact mechanical impedance within a stable processing window. The stable processing window refers to a processing state in which normal force fluctuation, temperature rise rate, vibration energy, and equivalent removal energy deviation are all within allowable ranges within a preset time range.

[0059] When the contact stiffness component increases or the vibration energy increases, the corresponding temperature threshold can be lowered, allowing the system to enter a protection state earlier. When the contact state is stable and the temperature fluctuation is small, the corresponding temperature threshold can be appropriately increased to reduce unnecessary load reduction. The vibration threshold can be dynamically adjusted according to the current workpiece stiffness, grinding head position, and phase relationship between adjacent grinding heads. When the phases of adjacent grinding heads tend to be synchronized, even if the vibration amplitude of a single grinding head does not exceed the fixed threshold, the controller 60 can trigger phase staggering or energy redistribution.

[0060] When the distance between the center of the polishing head and the edge of the workpiece is less than 1.2 times the radius of the polishing head, the controller 60 enters the edge control mode.

[0061] In edge control mode, the actual overlap area between the polishing head and workpiece 2 is less than the total contact area. Controller 60 adjusts the contact area A based on the actual overlap area. i This reduces the target energy removal distribution of the corresponding polishing head while limiting its target pressure F. i If the edge region still needs to achieve the target equivalent removal energy input density, the controller 60 selects a neighboring grinding head that has a removal contribution relationship with the edge region and is in a stable contact state through the spatial removal superposition matrix H. The neighboring grinding head undertakes part of the compensation removal amount, thereby reducing the risk of edge collapse caused by excessive local pressure at the edge.

[0062] In one embodiment, the multi-head collaborative polishing device 1 includes six polishing heads, each with a diameter of 150 mm. The center-to-center distance between adjacent polishing heads is 180 mm to 240 mm, and the ratio of the distance between the polishing heads to their diameter is 1.2 to 1.6. Each polishing head initially rotates at a speed of 600 r / min to 1500 r / min, and its initial normal load is 80 N to 350 N. During polishing, the controller 60 updates the single-head pressure closed loop at a 10 ms cycle and updates the global equivalent removal energy field at a 50 ms cycle.

[0063] When the contact temperature of the third grinding head 13 rises from 45°C to 68°C and the rate of temperature rise exceeds the adaptive temperature threshold, the controller 60 determines that the third grinding head 13 has a risk of heat concentration based on the contact mechanical impedance. The controller 60 reduces the target pressure of the third grinding head 13 by 12% to 35%, reduces its target rotational speed by 3% to 15%, and simultaneously allocates a portion of the target removal energy to the second grinding head 12 and the fourth grinding head according to the spatial removal superposition matrix H. The second grinding head 12 and the fourth grinding head only undertake the compensation removal amount when their contact mechanical impedance change, temperature rise rate, and vibration energy are all within the corresponding threshold ranges.

[0064] In another embodiment, the number of grinding heads is 3 to 16, the grinding head rotation speed is 150 r / min to 2800 r / min, the normal load of a single grinding head is 20 N to 800 N, the equivalent contact pressure is 0.01 MPa to 0.18 MPa, the workpiece feed speed is 5 mm / s to 150 mm / s, the polishing contact zone temperature is 20 °C to 85 °C, and the vibration frequency of the grinding head-workpiece system is mainly distributed between 8 Hz and 250 Hz. Within the above range, the controller 60 adaptively generates the target pressure and target rotation speed of each polishing grinding head based on the target equivalent removal energy field, contact mechanical impedance, temperature rise state, and vibration state.

[0065] In alternative embodiments, the normal force sensor 51 may be a piezoelectric force sensor, a strain gauge force sensor, or a thin-film force sensor; the contact temperature sensor 54 may be a thermocouple, an infrared temperature sensor, or an embedded thin-film temperature sensor; the displacement sensor 55 may be an eddy current displacement sensor, a grating displacement sensor, or a laser displacement sensor; and the triaxial vibration sensor 53 may be a piezoelectric accelerometer or a MEMS accelerometer.

[0066] In an alternative implementation, the spatial removal overlay matrix H can be obtained through pre-calibration or updated in real time based on the grinding head trajectory, the polishing pad 42 compression model, and online removal error. The target equivalent removal energy field can be determined based on the target surface shape, the amount of target material removed, previous measurement results, or the process formulation.

[0067] In alternative implementations, controller 60 may be an industrial control computer, motion controller, programmable logic controller, embedded controller, or a distributed control system composed of the aforementioned control units. Real-time computing unit 62 can perform contact mechanical impedance identification, equivalent energy input density calculation, spatial superposition matrix calculation, target pressure generation, target rotation speed generation, neighborhood compensation, and vibration phase misalignment via program instructions. These program instructions can be stored in a non-volatile storage medium and executed by a processor.

[0068] The working principle of this embodiment is as follows: Specifically, the adaptive pressure and speed control method for multi-head collaborative polishing described in this embodiment achieves full-domain coordination and adaptive adjustment through the following closed-loop control link. First, the multi-source state sensing module 50 collects multi-source signals such as normal force, speed, driving torque, vibration response, contact temperature, and axial displacement of each polishing head in real time, and inputs the above raw data to the real-time calculation unit 62 of the controller 60 through the data acquisition interface 61. After receiving the above data, the real-time calculation unit 62 synchronously calls the contact mechanical impedance identification module 70, and calculates the contact stiffness component, damping component, and phase lag component between each grinding head and the workpiece 2 based on the ratio of the change in normal force to the change in axial displacement, the amplitude-phase relationship between the vibration velocity response and the force response, and the phase difference between the spindle periodic disturbance signal and the normal force fluctuation signal, thereby outputting the real-time contact mechanical impedance of each grinding head. Based on this, the real-time calculation unit 62 further calls the equivalent removal energy field calculation module 80: First, the equivalent removal energy density calculation unit 81 maps the normal force, rotation speed, friction state, and contact mechanical impedance of each grinding head to an equivalent removal energy input density; then, the spatial removal superposition matrix unit 82 establishes a spatial removal superposition matrix based on the grinding head diameter, trajectory, and spacing, superimposing the energy input density of each grinding head onto each grid area on the workpiece surface to generate the actual equivalent removal energy field; finally, the target energy field comparison unit 83 compares the actual equivalent removal energy field with the target equivalent removal energy field, determines the energy deviation of each region, and reverses the initial target removal energy allocation of each grinding head. Subsequently, the real-time calculation unit 62 calculates the contact stability margin based on the contact mechanical impedance change, temperature rise state, and vibration state of each grinding head, and corrects the initial target removal energy allocation: reducing the allocation of grinding heads with sudden contact impedance changes, excessive temperature rise, or increased vibration, and transferring the reduced portion to neighboring grinding heads that meet the stability conditions according to the spatial removal superposition matrix, thereby obtaining the corrected target removal energy allocation. Based on this, the real-time computing unit 62 calls the collaborative pressure-speed control module 90 to generate target pressure and target speed for each grinding head under the constraint of the corrected target removal energy distribution. The control command is then sent to the pressure loading mechanism 20 and servo spindle 30 in the multi-grinding head execution module 10 via the execution command output interface 63, ensuring that the pressure and speed regulation of each grinding head are both constrained by the same equivalent removal energy field. During the closed-loop operation, the abnormal operating condition protection module 100 continuously receives real-time data from the contact mechanical impedance identification module 70 and the multi-source state sensing module 50, dynamically updating the temperature threshold, vibration threshold, and contact stiffness mutation threshold. When a grinding head parameter exceeds the limit or enters edge control mode, the abnormal operating condition protection module 100 directly triggers the controller 60 to forcibly reduce the target pressure and distribution of the corresponding grinding head and initiates neighborhood compensation or phase shifting operations.The changes in the physical state of each polishing head after the adjustment are collected again by the multi-source state sensing module 50 and transmitted back to the controller 60, forming a complete real-time closed loop of "sensing, recognizing, mapping, decision-making, execution, and re-sensing", which repeats continuously until the processing is completed.

[0069] During multi-head polishing, multiple polishing heads simultaneously contact the workpiece 2. The controller 60 first collects data on the normal force, rotational speed, driving torque, vibration response, contact temperature, and axial displacement of each polishing head. Based on the changes in normal force, axial displacement, vibration velocity response, and the phase relationship between the spindle periodic disturbance signal and the normal force fluctuation signal, the controller 60 identifies the contact mechanical resistance between each polishing head and the workpiece 2.

[0070] Subsequently, the controller 60 converts the normal force, angular velocity, effective friction radius, contact area, friction state coefficient, and contact stability coefficient of each polishing head into an equivalent removal energy input density. Contact mechanical impedance, temperature rise rate, and vibration energy are used to correct the contact stability coefficient, enabling the system to identify changes in the stable removal capacity of the corresponding polishing head.

[0071] Then, the controller 60 calculates the energy contribution of each polishing head to different grid regions on the surface of the workpiece 2 based on the spatial removal superposition matrix H, and obtains the actual equivalent removal energy field. The target energy field comparison unit 83 compares the target equivalent removal energy field with the actual equivalent removal energy field, determines the energy deviation of each region, and determines the target removal energy allocation of each polishing head based on the spatial removal superposition matrix H.

[0072] Before generating execution instructions, the controller 60 adjusts the target energy removal allocation based on the changes in contact mechanical impedance, temperature rise, and vibration of each polishing head. When a polishing head is in a stable contact, low temperature rise, and low vibration state, that polishing head can handle more target energy removal. When a polishing head experiences an increased temperature rise rate, increased vibration energy, or a sudden change in contact stiffness, the controller 60 reduces the target energy removal allocation for that polishing head and transfers the reduced target energy removal allocation to a neighboring polishing head that meets the contact stability conditions.

[0073] Finally, under the constraint of correcting the target removal energy distribution, the controller 60 generates the target pressure and target rotation speed for each polishing head. Pressure and rotation speed are no longer adjusted independently, but are mutually constrained under the same target equivalent removal energy field. When it is necessary to increase the removal amount and contact stability is required, pressure and rotation speed can be increased synergistically within a preset range; when the temperature rise or vibration approaches the threshold, the controller 60 limits the simultaneous increase of pressure and rotation speed, and maintains the consistency of the equivalent removal energy on the workpiece 2 surface through pressure reduction, rotation speed fine-tuning, or neighborhood compensation.

[0074] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An adaptive pressure and speed control method for multi-head collaborative polishing, characterized in that, Includes the following steps: S1, collect data on normal force, rotational speed, driving torque, vibration response, contact temperature and axial displacement of at least three polishing heads during the polishing process; S2, based on the normal force, the vibration response, the contact temperature, and the axial displacement data, identify the contact mechanical resistance between each polishing head and the workpiece; S3, based on the normal force, rotational speed, driving torque, contact area and contact mechanical resistance of each polishing head, determine the equivalent removal energy input density of each polishing head; S4. Based on the removal contribution relationship of each polishing head to different areas of the workpiece surface, a spatial removal superposition matrix is ​​established, and based on the spatial removal superposition matrix and the equivalent removal energy input density of each, the actual equivalent removal energy field of the workpiece surface is determined. S5, determine the target removal energy allocation amount corresponding to each polishing head based on the deviation between the target equivalent removal energy field and the actual equivalent removal energy field; S6. Based on the changes in contact mechanical resistance, temperature rise, and vibration of each polishing head, the target energy removal distribution is corrected to obtain the corrected target energy removal distribution for each polishing head. S7, under the constraint of the corrected target removal energy distribution, the target pressure and target speed of each polishing head are generated in a coordinated manner, so that the pressure adjustment and speed adjustment of each polishing head are jointly constrained by the target equivalent removal energy field.

2. The adaptive pressure and speed control method for multi-head collaborative polishing according to claim 1, characterized in that, The contact mechanical impedance includes a contact stiffness component, a damping component, and a phase lag component; wherein, the contact stiffness component is determined based on the change in normal force and the change in axial displacement, the damping component is determined based on the relationship between vibration velocity response and force response, and the phase lag component is determined based on the phase difference between the periodic disturbance signal of the main shaft and the normal force fluctuation signal.

3. The adaptive pressure and speed control method for multi-head collaborative polishing according to claim 1, characterized in that, The equivalent energy input density is determined based on the normal force, rotational speed, effective friction radius, contact area, friction state coefficient, and contact stability coefficient; wherein, the friction state coefficient is determined based on the driving torque, normal force, and effective friction radius, and the contact stability coefficient is corrected based on the contact mechanical impedance, vibration energy, and temperature rise rate.

4. The adaptive pressure and speed control method for multi-head collaborative polishing according to claim 1, characterized in that, The workpiece to be polished area is divided into multiple grid areas. Each element in the spatial removal superposition matrix represents the removal contribution coefficient of each polishing head to each grid area. The actual equivalent removal energy input density of each grid area is obtained by multiplying the equivalent removal energy input density of each polishing head by the corresponding removal contribution coefficient and then superimposing them.

5. The adaptive pressure and speed control method for multi-head collaborative polishing according to claim 4, characterized in that, The spatial removal overlay matrix is ​​determined based on at least two parameters among the following: grinding head diameter, polishing pad compression characteristics, grinding head motion trajectory, grinding head spacing, and workpiece feed speed.

6. The adaptive pressure and speed control method for multi-head collaborative polishing according to claim 1, characterized in that, In step S6, the removal requirement is first determined based on the deviation between the target equivalent removal energy field and the actual equivalent removal energy field, and then the removal requirement is allocated based on the contact stability margin of each polishing head. When the change in contact mechanical resistance of a certain polishing head increases, the rate of temperature rise increases, or the vibration energy increases, the target removal energy allocation corresponding to that polishing head is reduced, and the reduced target removal energy allocation is transferred to other polishing heads that have overlapping removal areas with that polishing head and whose contact stability margin is greater than a preset stability margin threshold, according to the contact stability margin.

7. The adaptive pressure and speed control method for multi-head collaborative polishing according to claim 1, characterized in that, In step S7, when the area corresponding to a certain polishing head needs to increase the removal amount and the polishing head is in a stable contact state, the target pressure and target rotation speed of the polishing head are allowed to increase synergistically within a preset constraint range; When the temperature rise rate or vibration energy of the polishing head approaches the corresponding threshold, the target pressure and target speed of the polishing head are limited to increase simultaneously, and the equivalent removal energy consistency of the workpiece surface is maintained by at least one of reducing the target pressure, adjusting the target speed, or transferring the target removal energy distribution.

8. The adaptive pressure and speed control method for multi-head collaborative polishing according to claim 1, characterized in that, When any polishing head reduces its target removal energy allocation due to increased temperature rise rate, increased vibration energy, sudden change in contact stiffness, or actuator saturation, a set of neighboring polishing heads is selected according to the spatial removal superposition matrix, and the reduced target removal energy allocation of the polishing head is redistributed according to the contact stability margin of each polishing head in the set of neighboring polishing heads; the polishing heads in the set of neighboring polishing heads have overlapping removal areas with the polishing head on the workpiece surface, and their contact mechanical resistance change, temperature rise rate, and vibration energy are all within the corresponding threshold range.

9. The adaptive pressure and speed control method for multi-head collaborative polishing according to claim 1, characterized in that, The dominant frequency and phase are extracted based on the vibration response of each polishing head. When the dominant frequency difference between adjacent polishing heads is less than a preset frequency difference threshold and the phase difference is less than a preset phase threshold, a rotational speed offset is applied to at least one adjacent polishing head to make the periodic disturbance phases of the adjacent polishing heads staggered. The rotational speed offset is 1% to 3% of the target rotational speed, and when the rotational speed offset is applied, the target pressure is adjusted synchronously to keep the equivalent removal energy input density of the corresponding region within the target range.

10. The adaptive pressure and speed control method for multi-head collaborative polishing according to claim 1, characterized in that, At least one of the temperature threshold, vibration threshold, and contact stiffness mutation threshold is dynamically updated based on historical data and current contact mechanical impedance within a stable processing window; when the distance from the center of the polishing head to the edge of the workpiece is less than 1.2 times the radius of the polishing head, the edge control mode is entered. In the edge control mode, the contact area is corrected according to the actual overlap area between the polishing head and the workpiece, the target energy removal distribution of the corresponding polishing head is reduced, and the target pressure of the corresponding polishing head is limited.

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