Active force-controlled grinding compensation module and control method

Abstract

The present invention discloses an active force-controlled grinding compensation module and control method, comprising a five-axis grinding machine and a workpiece adjustment rotating shaft, as well as a mounting plane, an X-axis fine-tuning compensation mechanism, a Y-axis fine-tuning compensation mechanism, a Z-axis fine-tuning compensation mechanism, a force sensor, a fixture, and a control system. The mounting plane of the workpiece adjustment rotating shaft is vertically mounted with the X-axis fine-tuning compensation mechanism, the Y-axis fine-tuning compensation mechanism, and the Z-axis fine-tuning compensation mechanism. The top of the Z-axis fine-tuning compensation mechanism is fixedly connected to a fixture for mounting the grinding workpiece. The force sensor is mounted between the fixture and the Z-axis fine-tuning compensation mechanism. The control system controls the five-axis grinding machine, the X-axis fine-tuning compensation mechanism, the Y-axis fine-tuning compensation mechanism, the Z-axis fine-tuning compensation mechanism, and the force sensor and receives data information. Advantages: The control method enables the compensation module to adapt to machining surfaces with large curvature changes. The compensation structure is arranged above the workpiece adjustment rotating shaft, requires little mass to be driven, and therefore has a small volume.

Description

Technical Field

[0001] The present invention relates to the technical field of grinding processing, and in particular to an active force-controlled grinding compensation module and a control method. Background Art

[0002] Existing 3C product shells or other workpieces that need to be polished are increasingly using complex surfaces or multi-surface connections, which increases the requirements for machine tools or robotic arm equipment, greatly increasing the cost of the equipment.

[0003] Existing technologies have proposed methods for polishing workpieces through constant-force grinding. Most common methods utilize a floating grinding head, with an adjustment mechanism comprised of a low-resistance cylinder, a servo proportional valve, and a displacement sensor. The entire system is passively adjusted, resulting in a complex structure and slow response. There are also methods that incorporate a force sensor at the end of the robotic arm's grinding process to provide force feedback to the robotic arm, which then performs position adjustment. However, grinding vibrations significantly impact the force sensor's sampling, and since the position adjustment signal is difficult to connect to the robotic arm's control system at the bottom level, this introduces significant latency. Furthermore, position adjustment is delegated to the robotic arm, and the ultimate result ultimately relies on the robotic arm's accuracy. Therefore, an active force-controlled grinding system is needed.

[0004] Patent application number CN116833855A discloses an active force-controlled grinding system that compensates only the Z and Y axes. The C-axis is positioned above the compensation platform, allowing for theoretical force-controlled compensation at any angle during grinding. However, this system cannot compensate for positioning errors in the machine's X-axis and accumulates errors when machining joints or complex curved surfaces, such as fillets. Because the C-axis is positioned above the compensation platform, fine-tuning the compensation requires a relatively large overall structural mass. Ensuring system rigidity requires a larger and heavier overall structure, ultimately creating a cycle that places high demands on the internal space of the multi-axis grinding machine. Furthermore, in practice, most multi-axis grinding machines place the force sensor at the bottom of the entire force-controlled system, which is affected by both the rigidity of the compensation platform system and its inertia during motion, impacting the final grinding effect. Furthermore, the system maintains constant force control, without any additional adjustment for changes in contact area caused by curvature variations on complex curved surfaces or when multiple surfaces connect, ultimately impacting the uniformity of the workpiece surface.

[0005] The Chinese utility model patent, with publication number CN216422106U, discloses a force-controlled compensation device and a five-axis CNC grinding machine, comprising a work platform; a mounting base slidably mounted on the work platform; a Y-axis drive mechanism comprising a Y-axis drive motor disposed adjacent to the mounting base and fixedly mounted on the work platform; and a connecting rod assembly mounted on the output end of the Y-axis drive motor, one end of the connecting rod assembly being hinged to the output end of the Y-axis drive motor and the other end being hinged to the mounting base to drive the sliding movement of the mounting base; and a force-controlled compensation mechanism mounted on the mounting base. Compared to existing technologies, this device effectively reduces the installation height of the force-controlled compensation mechanism, making the overall structure more compact and space-saving, while also improving stability and grinding accuracy. However, this application only implements position compensation in the Y-axis direction, making it incapable of adapting to complex curved surfaces that require grinding.

[0006] Chinese utility model patent publication number CN216298974U discloses a force compensation mechanism for grinding equipment, comprising: a work platform; a mounting base capable of horizontal and longitudinal movement relative to the work platform; a drive assembly mounted on the work platform, the drive assembly comprising a Y-axis drive assembly and a Z-axis drive assembly, the Y-axis drive assembly and the Z-axis drive assembly being configured to drive the mounting base to perform horizontal and longitudinal movement on the work platform without interfering with each other; a force control sensor fixed to the top of the mounting base; and a rotation assembly fixed to the top of the force control sensor, the rotation assembly being provided with a workpiece fixing assembly on top of the rotation assembly, the force control sensor being configured to detect real-time pressure of the workpiece fixing assembly in the horizontal and longitudinal directions, and the rotation assembly being configured to adjust the positioning angle of the workpiece fixing assembly within the horizontal plane. The mechanism can automatically achieve precise compensation during the grinding process. The rotation assembly is mounted above the compensation mechanism. When performing position compensation, the compensation mechanism needs to drive the rotation assembly to move together. This requires a relatively large overall mass of the structure to be driven. To ensure the rigidity of the system, a larger and heavier overall structure is required, placing high demands on the space required to install the compensation structure on the multi-axis grinding machine.

[0007] Patent publication number CN114952623B discloses a control method for actively controlling grinding force during grinding operations on a CNC machine tool. The method comprises: presetting a machining force based on workpiece characteristics and surroundings; actively applying an appropriate force to the workpiece against the grinding head based on the pre-set force; directly incorporating grinding force feedback directly into a driver via force sensor feedback for position control and calculations required for closed-loop control; calculating the compensation amount for the current distance between the grinding head and the workpiece based on the real-time feedback force; and maintaining the grinding force as constant as possible through real-time distance compensation. The control method for actively controlling grinding force during grinding operations on a CNC machine tool according to the present invention actively controls the driving motor of the grinding head based on the real-time feedback grinding force, thereby ensuring constant force control and motion accuracy during grinding operations on the CNC machine tool, enabling faster and more precise grinding operations. While the machining force is pre-set based on workpiece characteristics and surroundings, the method does not address the impact of variations in the actual grinding contact area due to varying surface shapes of the workpiece being ground on the pre-set grinding force and compensation amount.

[0008] Therefore, there is a need for an active force-controlled grinding compensation module that can adapt to grinding workpieces with different shapes and has low requirements for installation space. Summary of the Invention

[0009] The technical problem to be solved by the present invention is that the existing grinding compensation structure is affected by the installation position, resulting in a large volume and affecting the measurement structure. The constant force control cannot adjust to the processing surface with large curvature changes, which ultimately affects the uniformity of the workpiece surface processing.

[0010] In response to the above technical problems, an active force-controlled grinding compensation module is proposed; it is achieved through the following technical solutions:

[0011] It includes a five-axis grinder and a workpiece adjustment rotating shaft, as well as a mounting plane, an X-axis fine-tuning compensation mechanism, a Y-axis fine-tuning compensation mechanism, a Z-axis fine-tuning compensation mechanism, a force sensor, a fixture and a control system. The workpiece adjustment rotating shaft is installed on the five-axis grinder. The X-axis fine-tuning compensation mechanism, the Y-axis fine-tuning compensation mechanism, and the Z-axis fine-tuning compensation mechanism are vertically installed in sequence on the mounting plane of the workpiece adjustment rotating shaft to perform position fine-tuning compensation on the grinded workpiece on the fixture. The top of the Z-axis fine-tuning compensation mechanism is fixedly connected to the fixture, and the fixture is used to install the grinded workpiece. The fixture is provided with a negative pressure installation device including a quick connector, an air pipe and a negative pressure air port. The negative pressure air port is provided on the fixture. The fixture is connected to the air pipe through a quick connector to provide negative pressure to the negative pressure air port, and the grinded workpiece is fixed by the negative pressure. The force sensor is installed between the fixture and the Z-axis fine-tuning compensation mechanism to detect the grinding force on the grinded workpiece and the fixture. The control system controls the five-axis grinder, the X-axis fine-tuning compensation mechanism, the Y-axis fine-tuning compensation mechanism, the Z-axis fine-tuning compensation mechanism and the force sensor and receives data information.

[0012] The control system receives force sensor data and calculates the adjustment distance of the entire compensation module according to the change in the actual processing area of the workpiece. It then controls the displacement of the X-axis fine-tuning compensation mechanism, the Y-axis fine-tuning compensation mechanism, and the Z-axis fine-tuning compensation mechanism to perform position compensation, so that the compensation module can adapt to the processing surface with large curvature changes.

[0013] Preferably, the technical solution of the present invention is that the X-axis fine-tuning compensation mechanism includes a first base, a first slide rail, a first slider and a first micro-servo electric cylinder. The first base is fixedly mounted on the mounting plane of the workpiece adjustment rotating axis. The first base is provided with a first slide rail. The first micro-servo electric cylinder is mounted on the surface of the first base to drive the first slider to move on the first slide rail. The first slide rail is connected to the Y-axis fine-tuning compensation mechanism through the first slider. The X-axis fine-tuning compensation mechanism drives the workpiece to perform position compensation in the X-axis direction.

[0014] Preferably, the technical solution of the present invention is that the Y-axis fine-tuning compensation mechanism includes a second base, a second slide rail, a second slider and a second micro-servo electric cylinder. The second base is fixedly connected to the first slider. The surface of the second base is fixedly connected to the second slide rail and the second slide rail is arranged perpendicular to the first slide rail. The second slide rail is slidably connected to the second slider. The second micro-servo electric cylinder is installed on the surface of the second base to drive the second slider to move on the second slide rail. The Z-axis fine-tuning compensation mechanism is fixedly connected to the second slider. The Y-axis fine-tuning compensation mechanism drives the workpiece to perform position compensation in the Y-axis direction.

[0015] Preferably, the Z-axis fine-tuning compensation mechanism includes a third base, a third micro-servo electric cylinder, a guide column and a linear bearing. The third base is fixedly connected to the top of the second slider. A guide column and a linear bearing are provided at each of the four corners of the third base. A third micro-servo electric cylinder is also provided on the third base. The third base is connected to the fixture through the third micro-servo electric cylinder. The third micro-servo electric cylinder drives the fixture to move, thereby fine-tuning the Z-axis position of the workpiece.

[0016] Preferably, the X-axis fine-tuning compensation mechanism, the Y-axis fine-tuning compensation mechanism and the Z-axis fine-tuning compensation mechanism are provided with a protective shell on the outside. The protective shell includes an upper protective component and a lower protective component. The upper protective component is fixedly installed on the lower side of the fixture through a connecting plate, and the lower protective component is fixedly connected to the installation plane. The protective shell protects the internal structure and improves the stability of the equipment.

[0017] In the preferred embodiment of the technical solution of the present invention, a pipeline groove is provided in the lower protective component, and the power lines, network cables and negative pressure installation devices for providing negative pressure for the fixture of the X-axis fine-tuning compensation mechanism, the Y-axis fine-tuning compensation mechanism and the Z-axis fine-tuning compensation mechanism are installed in the pipeline groove and circled several times and connected from the groove to ensure that the wiring length margin can ensure the normal rotation of the workpiece adjustment rotating shaft.

[0018] In the preferred embodiment of the technical solution of the present invention, a protective cover is provided on the outside of the upper protective component, and a control circuit board is installed inside the protective cover. The X-axis fine-tuning compensation mechanism, the Y-axis fine-tuning compensation mechanism, the Z-axis fine-tuning compensation mechanism and the force sensor are connected to the control circuit board, which provides power for the X-axis fine-tuning compensation mechanism, the Y-axis fine-tuning compensation mechanism, the Z-axis fine-tuning compensation mechanism and the force sensor, receives data from the X-axis fine-tuning compensation mechanism, the Y-axis fine-tuning compensation mechanism, the Z-axis fine-tuning compensation mechanism and the force sensor, and the control circuit board connects to the control system through signals.

[0019] In addition, the present invention also relates to a control method for an active force-controlled grinding compensation module, comprising the following steps:

[0020] S1: Preparation: Input the 3D data of the polishing workpiece and the elastic modulus data of the polishing consumables into the control system;

[0021] Set the grinding adjustment threshold in the control system and the target pressure when the five-axis grinder grinds the workpiece;

[0022] The minimum adjustment step size of the compensation module is input into the control system. The workpiece is polished multiple times, the movement path of the compensation module is recorded, and the difference between the target polishing force and the actual measurement value is calculated. A neural network model is pre-trained to understand the relationship between the difference between the target polishing force and the actual measurement value and the movement path of the compensation module.

[0023] S2: Start working: The control system reads the position data of each axis of the five-axis grinder through the five-axis grinder CNC system, and obtains the equivalent grinding contact area of the workpiece at the real-time grinding position according to the 3D data of the workpiece input in S1, the position data of each axis of the five-axis grinder and the elastic modulus data of the grinding consumables;

[0024] S3: The control system calculates the target grinding force of the five-axis grinder according to the equivalent grinding contact area of the real-time grinding position and the target pressure when the five-axis grinder grinds the workpiece;

[0025] S4: The control system receives the actual measurement value of the force sensor, compares it with the target grinding force, and determines whether the difference between the two falls within a preset grinding adjustment threshold;

[0026] If it does not fall within the grinding adjustment threshold, it will directly enter S2. If it falls within the grinding adjustment threshold, it will enter S5.

[0027] S5: The control system inputs the difference between the actual measurement value of the force sensor and the target grinding force into the neural network model trained in S1 to generate the motion path of the compensation module's XYZ axes;

[0028] S6: The control system generates a position adjustment instruction based on the minimum adjustment step instruction and sends it to the compensation module via the EtherCAT Ethernet field bus to perform real-time adjustment of the XYZ three-axis position of the compensation module.

[0029] Preferably, the training method of the neural network model in S1 is as follows: the input layer receives x, the input value is modeled using the weight w, each hidden layer calculates the output, and the data is ready in the output layer, that is, the motion path of the compensation module is obtained; the neural network model is used to perform several times of workpiece position compensation, and the mean square error between the output value of the compensation module motion path and the actual detection compensation module motion path is used as the loss function, and then the hidden layer is returned and the weight is adjusted before re-polishing test to obtain the loss function value, and multiple iterations are performed until the loss function after training is less than the set value, the training is completed, and a trained neural network model is obtained.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The control system receives the force sensor data and calculates the adjustment distance of the entire compensation module according to the change in the actual processing area of the workpiece. It then controls the displacement of the X-axis fine-tuning compensation mechanism, the Y-axis fine-tuning compensation mechanism, and the Z-axis fine-tuning compensation mechanism to perform position compensation, so that the compensation module can adapt to the processing surface with large curvature changes.

[0032] 2. The compensation structure is arranged above the workpiece adjustment rotation axis. The overall mass of the structure that the compensation structure needs to drive is small, so the volume of the compensation structure is smaller than that of the existing technology;

[0033] 3. A negative pressure mounting device is installed on the fixture to fix the workpiece to be processed by negative pressure, which reduces the situation in which the clamping device of the tooling contacts the grinding knife when the compensation structure of the existing grinding equipment adjusts the position of the workpiece on the fixture, causing the clamping device to be damaged and affecting the judgment of the grinding position of the workpiece to be processed. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 FIG2 is a schematic diagram of the three-dimensional structure of an active force-controlled grinding compensation module of the present invention;

[0035] Figure 2 Shown is a front view of an active force-controlled grinding compensation module of the present invention;

[0036] Figure 3 The figure shows the three-dimensional structure of the internal structure of an active force-controlled grinding compensation module of the present invention. Figure 1 ;

[0037] Figure 4 The figure shows the three-dimensional structure of the internal structure of an active force-controlled grinding compensation module of the present invention. Figure 2 ;

[0038] Figure 5 Shown is a cross-sectional view of an active force-controlled grinding compensation module of the present invention;

[0039] Figure 6 Shown is a schematic structural diagram of the lower surface of the jig of the present invention;

[0040] Figure 7 Shown is a schematic structural diagram of the upper surface of the jig of the present invention;

[0041] Figure 8 Shown is a schematic structural diagram of the Z-axis fine-tuning compensation mechanism of the present invention;

[0042] Figure 9 Shown is a structural schematic diagram of the X-axis fine-tuning compensation mechanism of the present invention;

[0043] Figure 10 FIG2 is a schematic diagram of the control network structure of the active force-controlled grinding compensation module according to a preferred embodiment of the present invention;

[0044] Figure 11 FIG2 is a flow chart of a control method of an active force-controlled grinding compensation module according to a preferred embodiment of the present invention.

[0045] Explanation of the accompanying symbols: 1. Workpiece adjustment rotation axis; 2. Mounting plane; 3. X-axis fine-tuning compensation mechanism; 31. First base; 32. First slide rail; 33. First slider; 34. First micro-servo electric cylinder; 4. Y-axis fine-tuning compensation mechanism; 41. Second base; 42. Second slide rail; 43. Second slider; 44. Second micro-servo electric cylinder; 5. Z-axis fine-tuning compensation mechanism; 51. Third base; 52. Third micro-servo electric cylinder; 53. Guide column and linear bearing; 6. Force sensor; 7. Fixture; 8. Protective shell; 81. Upper protective component; 82. Lower protective component; 83. Connecting plate; 9. Protective cover; 10. Removable observation window; 11. Removable steel adapter sleeve; 12. Pipeline trough; 13. Quick connector; 14. Negative pressure air port. DETAILED DESCRIPTION

[0046] The following is a combination of the embodiments of the present invention Figures 1 to 11 , the technical solutions in the embodiments of the present invention are described in detail.

[0047] Example

[0048] like Figures 1 to 9 As shown, an active force-controlled grinding compensation module includes a five-axis grinder and a workpiece adjustment rotating axis 1, as well as a mounting plane 2, an X-axis fine-tuning compensation mechanism 3, a Y-axis fine-tuning compensation mechanism 4, a Z-axis fine-tuning compensation mechanism 5, a force sensor 6, a fixture 7 and a control system.

[0049] Definition: Set the rectangular coordinate system with the original installation position of the workpiece on the installation plane 2 of the workpiece adjustment rotation axis 1 as the origin, the workpiece adjustment rotation axis 1 as the C axis, the position of the fixture 7 as the top, and the position of the workpiece adjustment rotation axis 1 as the bottom.

[0050] The workpiece adjustment rotating shaft 1 is installed on the existing five-axis grinding machine to adjust the angular position of the workpiece on the C-axis.

[0051] The mounting plane 2 of the workpiece adjustment rotating axis 1 provides mounting locations for the X-axis fine-tuning compensation mechanism 3 , the Y-axis fine-tuning compensation mechanism 4 , and the Z-axis fine-tuning compensation mechanism 5 .

[0052] After the C-axis adjustment is completed, the X-axis fine-tuning compensation mechanism 3 fine-tunes the X-axis position of the workpiece, the Y-axis fine-tuning compensation mechanism 4 fine-tunes the Y-axis position of the workpiece, and the Z-axis fine-tuning compensation mechanism 5 fine-tunes the Z-axis position of the workpiece.

[0053] The fixture 7 is arranged on the Z-axis fine adjustment compensation mechanism 5 to provide a fixed position for processing the workpiece.

[0054] The force sensor 6 is arranged between the jig 7 and the Z-axis fine-tuning compensation mechanism 5 to detect the actual grinding force applied to the workpiece on the jig 7 .

[0055] The control system receives data from the original five-axis grinder CNC system, the X-axis fine-tuning compensation mechanism 3, the Y-axis fine-tuning compensation mechanism 4, the Z-axis fine-tuning compensation mechanism 5 and the force sensor 6, and controls the X-axis fine-tuning compensation mechanism 3, the Y-axis fine-tuning compensation mechanism 4 and the Z-axis fine-tuning compensation mechanism 5 to fine-tune the position of the workpiece.

[0056] The X-axis fine-tuning compensation mechanism 3 includes a first base 31, a first slide rail 32, a first slider 33 and a first micro-servo electric cylinder 34. The first base 31 is a thin metal plate with a rectangular cross-section, which is used to fix the X-axis fine-tuning compensation mechanism 3 and the workpiece adjustment rotation axis 1;

[0057] A first slide rail 32 is welded on the first base 31 . The first slide rail 32 includes two smooth metal blocks with an I-shaped cross section for slidingly mounting the first slider 33 . The first slide rail 32 is arranged in the X-axis direction of the rectangular coordinate system.

[0058] The first slider 33 is slidably connected to the first slide rail 32. The first slider 33 includes four slider bodies. Every two slider bodies are clamped on a metal block. The slider body is welded to the first micro servo electric cylinder 34 through the connecting block and the slider body. The first micro servo electric cylinder 34 drives the slider body to move along the first slide rail 32, thereby simultaneously fine-tuning the Y-axis fine-tuning compensation mechanism 4, the Z-axis fine-tuning compensation mechanism 5 and the X-axis position of the workpiece installed on the fixture 7.

[0059] The upper surface of the first slider 33 is fixedly connected to the Y-axis fine-tuning compensation mechanism 4 by screws. The Y-axis fine-tuning compensation mechanism 4 includes a second base 41 , a second slide rail 42 , a second slider 43 and a second micro servo electric cylinder 44 .

[0060] The second base 41 is a thin metal plate with a rectangular cross section, and is used to fix the X-axis fine-tuning compensation mechanism 3 and the Y-axis fine-tuning compensation mechanism 4 with screws.

[0061] A second slide rail 42 is welded to the upper surface of the second base 41. The second slide rail 42 includes two metal blocks with smooth surfaces and I-shaped cross-sections, which are used to slide and install the second slider 43. The second slide rail 42 is arranged perpendicular to the first slide rail 32 and is arranged in the Y-axis direction of the rectangular coordinate system.

[0062] The second slider 43 is slidably connected to the second slide rail 42. The second slider 43 includes four slider bodies. Every two slider bodies are clamped on a metal block. The second slider 43 is welded to the second micro servo electric cylinder 44 through a connecting block. The second micro servo electric cylinder 44 drives the second slider 43 to move along the Y-axis direction on the second slide rail 42, thereby fine-tuning the Z-axis fine-tuning compensation mechanism 5 and the Y-axis position of the workpiece installed on the fixture 7.

[0063] The Z-axis fine-tuning compensation mechanism 5 is welded on the upper surface of the second slider 43. The Z-axis fine-tuning compensation mechanism 5 includes a third base 51, a third micro-servo electric cylinder 52, a guide column and a linear bearing 53. The third base 51 is also a thin metal plate with a rectangular cross-section. A guide column and a linear bearing 53 are welded on each of the four corners of the upper surface of the third base 51. The guide column and the linear bearing 53 are metal rods.

[0064] Using multiple guide columns and linear bearings 53 to replace the traditional base requires a side wall for mounting the guide rail slider with sufficient rigidity but increased mass, further reducing the overall mass and space occupied by the active force control module.

[0065] The upper end of the third base 51 is connected to the mounting shell, which is a lightweight metal shell with a cavity inside. The third micro servo electric cylinder 52 passes through the internal cavity of the lightweight metal shell and is fixedly connected to the jig 7 by screws. The force sensor 6 is fixedly connected to the jig 7 by screws to detect the grinding force applied to the workpiece on the jig 7.

[0066] The force sensor 6 is arranged at the top of the Z-axis fine-tuning compensation mechanism 5, as close as possible to the fixture 7 and the workpiece to accurately and quickly measure the force on the workpiece during the processing, while avoiding the influence of the system stiffness of the X-axis fine-tuning compensation mechanism 3, the Y-axis fine-tuning compensation mechanism 4, and the Z-axis fine-tuning compensation mechanism 5 itself, reducing the influence of the inertia of the X-axis fine-tuning compensation mechanism 3, the Y-axis fine-tuning compensation mechanism 4, and the Z-axis fine-tuning compensation mechanism 5 itself during movement on the detection results of the force sensor 6, and providing a timely and correct adjustment data basis for the fine-tuning compensation structure; being arranged at the top can also avoid the influence of the mass of other mechanisms, and a smaller range sensor can be selected, which in disguise increases the resolution of the sensor, thereby improving the fine-tuning compensation effect and effectively reducing costs.

[0067] The X-axis fine-tuning compensation mechanism 3, the Y-axis fine-tuning compensation mechanism 4, and the Z-axis fine-tuning compensation mechanism 5 use micro-servo electric cylinders, which are highly integrated and effectively reduce the space occupied by traditional servo motors with lead screws and lead screw fixing seats. The first base 31, the second base 41, and the third base 51 all have U-shaped electric cylinder fixing seats and T-shaped electric cylinder push-pull seats fixed to their base plates by screws, which can provide hard limits for the fine-tuning compensation mechanism while transmitting power.

[0068] A negative pressure mounting device is provided on the jig 7, which fixes the position of the polished workpiece by negative pressure. The negative pressure mounting device includes a quick connector 13, an air pipe and a negative pressure air port 14, a detachable steel adapter sleeve 11 and the air pipe. The negative pressure air port 14 is provided on the jig 7. The jig 7 is connected to the quick connector 13 through the detachable steel adapter sleeve 11. The quick connector 13 is used to connect the air pipe. The air pipe provides negative pressure to the negative pressure air port 14 to fix the workpiece to be processed on the jig 7. The negative pressure mounting device is installed on the jig to fix the workpiece to be processed by negative pressure, thereby reducing the situation in which the clamping device in the existing polishing equipment contacts the polishing knife during polishing, causing damage to the clamping device.

[0069] A protective shell 8 is provided on the outside of the X-axis fine-tuning compensation mechanism 3, the Y-axis fine-tuning compensation mechanism 4 and the Z-axis fine-tuning compensation mechanism 5. The protective shell 8 includes an upper protective component 81 and a lower protective component 82. The upper protective component 81 is fixedly mounted on the lower side of the fixture 7 through a connecting plate 83 and is a cylindrical protective metal shell. The lower protective component 82 is welded to the mounting surface 2. The lower protective component 82 is a cylindrical protective metal shell with a radius smaller than the upper protective component 81. The protective shell 8 protects the internal structure, provides isolation protection against polishing liquid, etc. during processing, and improves the stability of equipment use.

[0070] A pipeline groove 12 is provided in the lower protective component 82. The power lines, network cables and air pipes for providing negative pressure for the fixture 7 of the X-axis fine-tuning compensation mechanism 3, the Y-axis fine-tuning compensation mechanism 4 and the Z-axis fine-tuning compensation mechanism 5 are installed in the pipeline groove 12 and spiraled several times and connected from the groove to ensure that the wiring length margin can ensure the normal rotation of the workpiece adjustment rotating shaft 1.

[0071] A protective cover 9 is welded to the outside of the upper protective component 81, and a control circuit board is installed inside the protective cover 9 to provide power for the X-axis fine-tuning compensation mechanism 3, the Y-axis fine-tuning compensation mechanism 4, the Z-axis fine-tuning compensation mechanism 5 and the force sensor 6, and receive data from the X-axis fine-tuning compensation mechanism 3, the Y-axis fine-tuning compensation mechanism 4, the Z-axis fine-tuning compensation mechanism 5 and the force sensor 6. The control circuit board is connected to the control system via a wireless signal. A detachable observation window 10 is designed on the protective cover 9, which is easy to monitor its working status display light and disassemble and replace.

[0072] The compensation structure is arranged above the workpiece adjustment rotating shaft 1, and there is no need to drive the workpiece adjustment rotating shaft 1 to move. Therefore, the overall mass of the structure that the compensation structure needs to drive is relatively small, and there is no need to require a larger and heavier overall structure to ensure the rigidity of the system. Therefore, the overall volume of the compensation module in this application is smaller than that of the existing technology.

[0073] like Figures 10-11 As shown, the control method of the active force-controlled grinding compensation module includes the following steps:

[0074] S1: Preparation: Input the 3D data of the polishing workpiece and the elastic modulus data of the polishing consumables into the control system;

[0075] Set the grinding adjustment threshold in the control system and the target pressure when the five-axis grinder grinds the workpiece;

[0076] The minimum adjustment step size of the compensation module is input into the control system. The workpiece is polished multiple times, the movement path of the compensation module is recorded, and the difference between the target polishing force and the actual measurement value is calculated. A neural network model is pre-trained to understand the relationship between the difference between the target polishing force and the actual measurement value and the movement path of the compensation module.

[0077] S2: Start working: The control system reads the position data of each axis of the five-axis grinder through the five-axis grinder CNC system, and obtains the equivalent grinding contact area of the workpiece at the real-time grinding position according to the 3D data of the workpiece input in S1, the position data of each axis of the five-axis grinder and the elastic modulus data of the grinding consumables;

[0078] S3: The control system calculates the target grinding force of the five-axis grinder according to the equivalent grinding contact area of the real-time grinding position and the target pressure when the five-axis grinder grinds the workpiece;

[0079] S4: The control system receives the actual measurement value of the force sensor, compares it with the target grinding force, and determines whether the difference between the two falls within a preset grinding adjustment threshold;

[0080] If it does not fall within the grinding adjustment threshold, it will directly enter S2. If it falls within the grinding adjustment threshold, it will enter S5.

[0081] S5: The control system inputs the difference between the actual measurement value of the force sensor and the target grinding force into the neural network model trained in S1 to generate the motion path of the compensation module's XYZ axes;

[0082] S6: The control system generates a position adjustment instruction based on the minimum adjustment step instruction and sends it to the compensation module via the EtherCAT Ethernet field bus to perform real-time adjustment of the XYZ three-axis position of the compensation module.

[0083] In this embodiment, the position compensation principle of the grinding compensation module is as follows: the positions of each axis read from the CNC system of the five-axis grinder and the 3D data of the workpiece and the elastic modulus data of the grinding consumables input into the control system of the grinding compensation module will calculate the equivalent grinding contact area of the real-time grinding position, and then calculate the equivalent grinding force of the real-time grinding position with the input grinding pressure instruction, and compare it with the actual measurement data of the force sensor to reach the input grinding adjustment threshold instruction. After that, the specific adjustment instruction of the three-axis fine-tuning compensation platform is generated according to the minimum adjustment step instruction, and finally sent to the three-axis fine-tuning compensation platform actuator for real-time adjustment.

[0084] In this embodiment, the control system of the module only reads the position data of each axis of the original five-axis grinder's CNC system, bypassing the original five-axis grinder's CNC system and not needing to be integrated into the original five-axis grinder's CNC system.

[0085] In step S1 of this embodiment, the elastic modulus data of the consumables is provided by the consumables supplier, and the operator manually inputs the data into the system during the parameter setting process. The 3D data of the processed workpiece is provided by Party A, which is a standard neural network model of the processed workpiece. When used, the operator needs to manually upload the neural network model to the control system, or input the data set of the neural network model into the control system.

[0086] The grinding adjustment threshold in the control system is set by performing multiple grinding tests on a workpiece to obtain the grinding effects of multiple grindings, the actual measurement value of the force sensor and the target grinding force data. According to the grinding effect, the difference range between the actual measurement value of the force sensor and the target grinding force in this system is determined, that is, the grinding adjustment threshold.

[0087] The target pressure when the five-axis grinder grinds the workpiece is the input value entered by the user at the input end of the control system.

[0088] The minimum adjustment step of the compensation module is input into the control system. The minimum adjustment step of the three axes of X-axis, Y-axis and Z-axis is the set value entered manually. The adjustment distance of the single axis direction in each control cycle is the minimum adjustment step, and the minimum adjustment step can be 0.01cm.

[0089] A neural network model of the relationship between the difference between the target grinding force and the actual measurement value of the force sensor and the motion path of the compensation module is pre-trained based on multiple measurement results, where the actual motion path of the compensation module is obtained by performing contour cutting on the workpiece.

[0090] The training method of the neural network model in S1 is as follows: the input layer receives x, the input value is modeled using the weight w, each hidden layer calculates the output, and the data is ready in the output layer, that is, the compensation module motion path is obtained; the neural network model is used to perform several workpiece position compensations, the input layer receives x as the difference between the actual motion path of the compensation module and the target grinding force and the actual measurement value of the force sensor, and the mean square error between the output value of the compensation module motion path and the actual detection compensation module motion path is used as the loss function, and then returns to the hidden layer and adjusts the weight and then re-performs the grinding test to obtain the loss function value, and performs multiple iterations until the loss function after training is less than the set value. The training is completed and a trained neural network model is obtained.

[0091] In the pre-run process, the compensation module is first not working, the five-axis grinder is adjusted until the value of the force sensor is the target grinding force, and the grinding effect is observed. Then the compensation module is started to fine-tune the processed workpiece, and the data of the force sensor is recorded as the actual measurement value of the force sensor, as well as the change in the grinding effect. According to the range of change in the grinding effect, the data of the force sensor is recorded as the range of the actual measurement value of the force sensor. The difference between the actual measurement value of the force sensor and the target grinding force is used as the grinding adjustment threshold.

[0092] During the fine-tuning process of the compensation module, the workpiece is profiled to obtain the movement path of the compensation module. Combined with the difference between the target grinding force and the actual measurement value of the force sensor, a neural network model of the relationship between the difference between the target grinding force and the actual measurement value of the force sensor and the movement path of the compensation module is trained.

[0093] In this implementation method, a neural network model of the relationship between the difference between the target grinding force and the actual measurement value of the force sensor and the movement path of the compensation module is trained in advance, so that the system can quickly calculate the movement path of the compensation module and reduce the lag of the compensation module.

[0094] In step S2 of this embodiment, the control system reads the position data of each axis of the five-axis grinder through the five-axis grinder CNC system, and calculates the position change of the workpiece based on the 3D data of the workpiece input in S1 and the position data of each axis of the five-axis grinder.

[0095] The position change of the processed workpiece and the elastic modulus data of the grinding consumables are compared and calculated with the position change of the grinding consumables with different elastic moduli under force and the grinding contact area detected in advance to obtain the area at the same stress and the equivalent grinding contact area of the workpiece at the real-time grinding position.

[0096] In step S3 of this embodiment, the control system calculates the target grinding force of the five-axis grinder according to the equivalent grinding contact area of the real-time grinding position and the target pressure when the five-axis grinder grinds the workpiece.

[0097] The target grinding force is the product of the equivalent grinding contact area and the target pressure.

[0098] In step S4 of this embodiment, the control system receives the actual measurement value of the force sensor, compares it with the target grinding force, and determines whether the difference between the two falls within a preset grinding adjustment threshold;

[0099] If it does not fall within the grinding adjustment threshold, it will directly enter S2. If it falls within the grinding adjustment threshold, it will enter S5.

[0100] If the difference between the actual measurement value of the sensor and the target grinding force does not fall within the grinding adjustment threshold, it means that the grinding effect is good, so there is no need to fine-tune the position. After the grinding angle of the workpiece is changed, re-enter step S2. If the difference between the actual measurement value of the sensor and the target grinding force falls within the grinding adjustment threshold, the grinding effect of the workpiece is poor, and the compensation module needs to fine-tune the workpiece position.

[0101] In step S5 of this embodiment, the control system inputs the actual measurement value of the force sensor into the neural network model of the relationship between the target grinding force and the actual measurement value of the force sensor and the motion of the compensation module trained in S1 to generate the motion path of the compensation module XYZ three axes. As the number of grinding times increases, the neural network model of the relationship between the target grinding force and the actual measurement value of the force sensor and the motion of the compensation module will become more and more accurate.

[0102] In step S6 of this embodiment, the control system generates a position adjustment instruction based on the minimum adjustment step instruction and sends it to the compensation module via the EtherCAT Ethernet field bus to perform real-time adjustment of the XYZ three-axis position of the compensation module to optimize the grinding efficiency of the grinder.

[0103] This structure is intuitive and easy to operate. It can fine-tune and compensate multiple workstations in the same five-axis grinding machine with different parameter settings, so as to conduct process tests with different parameters more quickly. In addition, this structure is easy to expand the workstations and has good adaptability and economy for different numbers of workstations in different situations.

[0104] The control system also includes a screen located outside the five-axis grinding machine for interactive display, or a control screen connected to the original grinding machine. The internal part only needs to be connected to a power cord and an eight-core network cable from the outside, which is connected by a ten-core waterproof aviation plug to ensure its safe and reliable protection.

[0105] Through the above-mentioned grinding compensation module control method, the equivalent area and equivalent grinding force of surfaces with different curvatures are calculated and compared with the force value measured by the sensor. The three-axis platform performs fine-tuning compensation to achieve a constant-pressure grinding effect. Different pressures, adjustment thresholds, adjustment step sizes and other parameters can be applied to multiple workstations for simultaneous processing, making the exploration of process parameters and data collection more convenient and quick.

[0106] The above embodiments are only for illustrating the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. An active force-controlled grinding compensation module, comprising a five-axis grinding machine and a workpiece adjustment rotating shaft (1), characterized in that: The invention also includes a mounting plane (2), an X-axis fine-tuning compensation mechanism (3), a Y-axis fine-tuning compensation mechanism (4), a Z-axis fine-tuning compensation mechanism (5), a force sensor (6), a fixture (7) and a control system. The workpiece adjustment rotating shaft (1) is mounted on a five-axis grinding machine. The X-axis fine-tuning compensation mechanism (3), the Y-axis fine-tuning compensation mechanism (4), and the Z-axis fine-tuning compensation mechanism (5) are vertically mounted on the mounting plane (2) of the workpiece adjustment rotating shaft (1) in sequence to perform position fine-tuning compensation on the grinding workpiece on the fixture (7). The top of the Z-axis fine-tuning compensation mechanism (5) is fixedly connected to the fixture (7). The fixture (7) is used to mount the grinding workpiece. The fixture (7) A negative pressure installation device is provided on the fixture (7), including a quick connector (13), an air pipe and a negative pressure air port (14). The negative pressure air port (14) is provided on the fixture (7). The fixture (7) is connected to the air pipe through the quick connector (13) to provide negative pressure for the negative pressure air port (14). The grinding workpiece is fixed by the negative pressure. The force sensor (6) is installed between the fixture (7) and the Z-axis fine-tuning compensation mechanism (5) to detect the grinding force applied to the grinding workpiece and the fixture (7). The control system controls the five-axis grinder, the X-axis fine-tuning compensation mechanism (3), the Y-axis fine-tuning compensation mechanism (4), the Z-axis fine-tuning compensation mechanism (5) and the force sensor (6) and receives data information. The X-axis fine-tuning compensation mechanism (3) comprises a first base (31), a first slide rail (32), a first slider (33) and a first micro-servo electric cylinder (34); the first base (31) is fixedly mounted on the mounting plane (2) of the workpiece adjustment rotation axis (1); a first slide rail (32) is provided on the first base (31); a first micro-servo electric cylinder (34) is mounted on the surface of the first base (31) to drive the first slider (33) to move on the first slide rail (32); and the first slide rail (32) is connected to the Y-axis fine-tuning compensation mechanism (4) via the first slider (33); The Y-axis fine-tuning compensation mechanism (4) comprises a second base (41), a second slide rail (42), a second slider (43) and a second micro-servo electric cylinder (44); the second base (41) is fixedly connected to the first slider (33); the surface of the second base (41) is fixedly connected to the second slide rail (42), and the second slide rail (42) is vertically arranged with the first slide rail (32); the second slide rail (42) is slidably connected to the second slider (43); a second micro-servo electric cylinder (44) is installed on the surface of the second base (41) to drive the second slider (43) to move on the second slide rail (42); and the second slider (43) is fixedly connected to the Z-axis fine-tuning compensation mechanism (5); The Z-axis fine-tuning compensation mechanism (5) includes a third base (51), a third micro-servo electric cylinder (52), a guide column and a linear bearing (53). The third base (51) is fixedly connected to the top of the second slider (43). A guide column and a linear bearing (53) are respectively provided at the four corners of the third base (51). A third micro-servo electric cylinder (52) is also provided on the third base (51). The third base (51) is connected to the fixture (7) through the third micro-servo electric cylinder (52). The third micro-servo electric cylinder (52) drives the fixture (7) to move.

2. The active force-controlled grinding compensation module according to claim 1, characterized in that: A protective shell (8) is provided on the outside of the X-axis fine-tuning compensation mechanism (3), the Y-axis fine-tuning compensation mechanism (4), and the Z-axis fine-tuning compensation mechanism (5). The protective shell (8) includes an upper protective component (81) and a lower protective component (82). The upper protective component (81) is fixedly mounted on the lower side of the fixture (7) through a connecting plate (83), and the lower protective component (82) is fixedly connected to the mounting plane (2).

3. The active force-controlled grinding compensation module according to claim 2, characterized in that: A pipeline groove (12) is provided in the lower protective component (82), and power cables and network cables of the X-axis fine-tuning compensation mechanism (3), the Y-axis fine-tuning compensation mechanism (4), and the Z-axis fine-tuning compensation mechanism (5) and a negative pressure installation device for providing negative pressure for the fixture (7) are installed in the pipeline groove (12).

4. The active force-controlled grinding compensation module according to claim 2, characterized in that: A protective cover (9) is provided on the outside of the upper protective component (81), and a control circuit board is installed inside the protective cover (9). The X-axis fine-tuning compensation mechanism (3), the Y-axis fine-tuning compensation mechanism (4), the Z-axis fine-tuning compensation mechanism (5) and the force sensor (6) are connected to the control circuit board, which provides power to the X-axis fine-tuning compensation mechanism (3), the Y-axis fine-tuning compensation mechanism (4), the Z-axis fine-tuning compensation mechanism (5) and the force sensor (6), receives data from the X-axis fine-tuning compensation mechanism (3), the Y-axis fine-tuning compensation mechanism (4), the Z-axis fine-tuning compensation mechanism (5) and the force sensor (6), and the control circuit board is connected to the control system through signals.

5. The control method of the active force-controlled grinding compensation module according to any one of claims 1 to 4, characterized in that: The steps include: S1: Preparation: Input the 3D data of the polishing workpiece and the elastic modulus data of the polishing consumables into the control system; Set the grinding adjustment threshold in the control system and the target pressure when the five-axis grinder grinds the workpiece; The minimum adjustment step size of the compensation module is input into the control system. The workpiece is polished multiple times, the movement path of the compensation module is recorded, and the difference between the target polishing force and the actual measurement value is calculated. A neural network model is pre-trained to understand the relationship between the difference between the target polishing force and the actual measurement value and the movement path of the compensation module. S2: Start working: The control system reads the position data of each axis of the five-axis grinder through the five-axis grinder CNC system, and obtains the equivalent grinding contact area of the workpiece at the real-time grinding position according to the 3D data of the workpiece input in S1, the position data of each axis of the five-axis grinder and the elastic modulus data of the grinding consumables; S3: The control system calculates the target grinding force of the five-axis grinder according to the equivalent grinding contact area of the real-time grinding position and the target pressure when the five-axis grinder grinds the workpiece; S4: The control system receives the actual measurement value of the force sensor, compares it with the target grinding force, and determines whether the difference between the two falls within a preset grinding adjustment threshold; If it does not fall within the grinding adjustment threshold, it will directly enter S2. If it falls within the grinding adjustment threshold, it will enter S5. S5: The control system inputs the difference between the actual measurement value of the force sensor and the target grinding force into the neural network model trained in S1 to generate the motion path of the compensation module's XYZ axes; S6: The control system generates a position adjustment instruction based on the minimum adjustment step instruction and sends it to the compensation module via the EtherCAT Ethernet field bus to perform real-time adjustment of the XYZ three-axis position of the compensation module.

6. The control method of the active force-controlled grinding compensation module according to claim 5, characterized in that: The training method of the neural network model in S1 is as follows: the input layer receives x, uses weights w to model the input value, each hidden layer calculates the output, and the data is ready in the output layer, that is, the compensation module movement path is obtained; The neural network model is used to perform several times of workpiece position compensation. The mean square error between the output value of the compensation module motion path and the actual detection compensation module motion path is used as the loss function. The hidden layer is then returned and the weight is adjusted before re-polishing the test to obtain the loss function value. Multiple iterations are performed until the loss function after training is less than the set value. The training is completed and a trained neural network model is obtained.

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