Active force control grinding compensation module and control method

Abstract

The active force control grinding compensation module comprises a five-axis grinding machine and a workpiece adjusting rotating shaft, and further comprises a mounting plane, an X-axis fine adjustment compensation mechanism, a Y-axis fine adjustment compensation mechanism, a Z-axis fine adjustment compensation mechanism, a force sensor, a jig and a control system. The X-axis fine-adjustment compensation mechanism, the Y-axis fine-adjustment compensation mechanism and the Z-axis fine-adjustment compensation mechanism are vertically and sequentially installed on the installation plane of the workpiece adjustment rotating shaft, the top end of the Z-axis fine-adjustment compensation mechanism is fixedly connected with the jig, the jig is used for installing a polishing workpiece, and the force sensor is installed between the jig and the Z-axis fine-adjustment compensation mechanism. The control system controls the five-axis grinding machine, the X-axis fine adjustment compensation mechanism, the Y-axis fine adjustment compensation mechanism, the Z-axis fine adjustment compensation mechanism and the force sensor and receives data information. The control method has the advantages that the compensation module adapts to the machining surface with large curvature change due to the control mode, the compensation structure is arranged above the workpiece adjusting rotating shaft, the needed driving mass is small, and therefore the size is small.

Description

Technical Field

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

[0002] Complex curved surfaces or the connection of multiple curved surfaces are increasingly used on the shells of existing 3C products or other workpieces that need to be ground and polished, which raises the requirements for machine tools or robotic arm equipment, greatly increasing the cost of the equipment.

[0003] The prior art has proposed to achieve grinding and polishing of workpieces through the method of constant force grinding. Most of its common methods use a floating grinding head, and the adjustment mechanism is composed of a low-resistance cylinder, a servo proportional valve, a displacement sensor, etc. The entire system is adjusted passively, with a complex structure and a slow response speed. At the same time, a force sensor is added to the execution end of the robotic arm grinding, and the force is fed back to the robotic arm for position adjustment by the robotic arm. However, the vibration during grinding has a great impact on the sampling of the force sensor itself, and it is difficult to integrate the position adjustment signal with the control system of the robotic arm itself from the bottom layer, resulting in a large delay. Moreover, the position adjustment is completed by the robotic arm, and actually the final effect still depends on the accuracy of the robotic arm itself. Therefore, an active force control grinding system is needed.

[0004] The invention patent application with the publication number of CN116833855A: The present invention discloses an active force control grinding system, which only compensates for the Z-axis and Y-axis. The C-axis is designed above the compensation platform, so theoretically, force control compensation at any angle during grinding can be completed. However, it cannot compensate for the positioning error of the X-axis of the machine tool itself, and cumulative errors will also occur during the processing of connection surfaces or complex curved surfaces such as rounded corners; since the C-axis is designed above the compensation platform, the overall mass of the structure that needs to be driven for fine adjustment compensation is relatively large. In order to ensure the stiffness of the system, a larger and heavier overall structure is required, ultimately falling into a cycle, which poses high requirements for the space inside the multi-axis grinding special machine; and in actual layout, most multi-axis grinding special machines arrange the force sensor at the bottom of the entire force control system, which is affected by both the stiffness of the compensation platform system and the inertia during the movement of the compensation platform, affecting the final grinding effect; its control is still constant force control, and there is no additional adjustment and adaptation to the change in the contact area caused by the curvature change during the connection of complex curved surfaces and multiple curved surfaces, ultimately affecting the uniformity of the surface processing of the workpiece.

[0005] Chinese Utility Model Patent with Publication No. CN216422106U: A Force Control Compensation Device and a Five-Axis CNC Grinding Machine, which includes a working platform; a mounting seat slidably mounted on the working platform; a Y-axis driving mechanism, the Y-axis driving mechanism includes a Y-axis driving motor disposed beside the mounting seat and fixedly mounted on the working platform, and a connecting rod assembly mounted on the output end of the Y-axis driving motor, one end of the connecting rod assembly is hinged to the output end of the Y-axis driving motor, and the other end is hinged to the mounting seat to drive the sliding of the mounting seat; a force control compensation mechanism mounted on the mounting seat. Compared with the prior art, this device can effectively reduce the installation height of the force control compensation mechanism, making the structure of the whole machine more compact and occupying less space. At the same time, it improves the stability and grinding accuracy during grinding. However, only the position compensation in the Y-axis direction is realized in this application, and it cannot adapt to complex curved surfaces that need to be ground.

[0006] Chinese Utility Model Patent with Publication No. CN216298974U: Disclosed is a force compensation mechanism for a grinding device, including: a working platform; a mounting seat that can move horizontally and longitudinally relative to the working platform; a driving assembly mounted on the working platform, the driving assembly includes a Y-axis driving assembly and a Z-axis driving assembly, and the Y-axis driving assembly and the Z-axis driving assembly are used to drive the mounting seat to move horizontally and longitudinally on the working platform without interference; a force control sensor fixed to the top of the mounting seat; a rotating assembly fixed to the top of the force control sensor, a workpiece fixing assembly is provided at the top of the rotating assembly, and the force control sensor is used to detect the real-time pressure of the workpiece fixing assembly in the horizontal and longitudinal directions, and the rotating assembly is used to adjust the positioning angle of the workpiece fixing assembly in the horizontal plane; In summary, it can automatically achieve precise compensation during the grinding process. The rotating assembly is installed above the compensation mechanism. When the compensation mechanism performs position compensation, it needs to drive the rotating assembly to move together, and the overall mass of the structure that needs to be driven is relatively large. In order to ensure the stiffness of the system, a larger and heavier overall structure is required. Therefore, high requirements are put forward for the space of the multi-axis grinding special machine to install the compensation structure.

[0007] In the invention patent with the publication number CN114952623B, a control method for the grinding operation of a numerically controlled machine tool for actively controlling the grinding force is disclosed, which includes: setting the magnitude of the processing force in advance according to the workpiece characteristics and the surroundings; actively approaching the grinding head with the workpiece with an appropriate force according to the preset force magnitude; through the feedback of the force sensor, directly introducing the feedback of the grinding force into the driver for position control and performing the calculations required for closed-loop control; calculating through the force feedback in real time to determine the compensation amount of the distance between the current grinding head and the workpiece; and making the grinding force as constant as possible through real-time distance compensation. According to the control method for the grinding operation of a numerically controlled machine tool for actively controlling the grinding force of the present invention, by actively controlling the drive motor of the grinding head by combining the grinding force feedback in real time, the constant force control and the motion accuracy control of the numerically controlled machine tool grinding can be ensured, so that a faster and more accurate grinding operation can be achieved. According to the workpiece characteristics and the surroundings, the magnitude of the processing force is set in advance, and the influence of the change in the actual grinding contact area caused by the different shapes of the grinding surfaces of the workpiece to be ground on the preset grinding force and the compensation amount is not introduced.

[0008] Therefore, an active force control grinding compensation module that can adapt to different shaped surfaces of grinding workpieces and has low requirements for the installation space is needed. 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 be adjusted to adapt to the machining surface with a large curvature change, ultimately affecting the uniformity of the workpiece surface machining.

[0010] In view of the above technical problems, an active force control grinding compensation module is proposed; it is realized through the following technical solutions: It includes a five-axis grinding machine and a workpiece adjustment rotating shaft, and also includes an installation plane, an X-axis fine adjustment compensation mechanism, a Y-axis fine adjustment compensation mechanism, a Z-axis fine adjustment compensation mechanism, a force sensor, a fixture and a control system. The workpiece adjustment rotating shaft is installed on the five-axis grinding machine. The X-axis fine adjustment compensation mechanism, the Y-axis fine adjustment compensation mechanism, and the Z-axis fine adjustment compensation mechanism are vertically installed in sequence on the installation plane of the workpiece adjustment rotating shaft to perform position fine adjustment compensation on the grinding workpiece on the fixture. The top of the Z-axis fine adjustment compensation mechanism is fixedly connected to the fixture. The fixture is used to install the grinding 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 arranged on the fixture. The fixture connects the air pipe through the quick connector to provide negative pressure for the negative pressure air port, and fixes the grinding workpiece through negative pressure. The force sensor is installed between the fixture and the Z-axis fine adjustment compensation mechanism to detect the grinding force received by the grinding workpiece and the fixture. The control system controls the five-axis grinding machine, the X-axis fine adjustment compensation mechanism, the Y-axis fine adjustment compensation mechanism, the Z-axis fine adjustment compensation mechanism and the force sensor and receives data information.

[0011] The force sensor data is received through the control system, and then the adjustment distance of the entire compensation module is calculated according to the change in the actual machining area of the workpiece to be machined. Then, the X-axis fine adjustment compensation mechanism, Y-axis fine adjustment compensation mechanism, and Z-axis fine adjustment compensation mechanism are controlled to displace for position compensation, so that the compensation module adapts to the machining surface with a large curvature change.

[0012] Preferably, the X-axis fine adjustment 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 installed on the installation plane of the workpiece adjustment rotating shaft. A first slide rail is provided on the first base. The first micro servo electric cylinder is installed 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 adjustment compensation mechanism through the first slider, and the X-axis fine adjustment compensation mechanism drives the workpiece to perform position compensation in the X-axis direction.

[0013] Preferably, the Y-axis fine adjustment 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 second slide rail is fixedly connected to the surface of the second base and is 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 adjustment compensation mechanism is fixedly connected to the second slider, and the Y-axis fine adjustment compensation mechanism drives the workpiece to perform position compensation in the Y-axis direction.

[0014] Preferably, the Z-axis fine adjustment compensation mechanism includes a third base, a third micro servo electric cylinder, a guide post, and a linear bearing. The third base is fixedly connected above the second slider. A guide post 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, and the third micro servo electric cylinder drives the fixture to displace for fine adjustment of the Z-axis position of the workpiece.

[0015] Preferably, a protective housing is provided outside the X-axis fine adjustment compensation mechanism, Y-axis fine adjustment compensation mechanism, and Z-axis fine adjustment compensation mechanism. The protective housing includes an upper protective component and a lower protective component. The upper protective component is fixedly installed under the fixture through a connecting plate, and the lower protective component is fixedly connected to the installation plane. The protective housing protects the internal structure and improves the stability of equipment use.

[0016] Preferably, a pipeline groove is provided in the lower protective component. The power lines, network cables of the X-axis fine adjustment compensation mechanism, Y-axis fine adjustment compensation mechanism, Z-axis fine adjustment compensation mechanism, and the negative pressure installation device for providing negative pressure to the fixture are installed in the pipeline groove and coiled several times and led out from the groove opening to ensure that the remaining length of the wire routing can ensure the normal rotation of the workpiece adjustment rotating shaft.

[0017] Preferably, for the technical solution of the present invention, a protective cover is provided on the outer side of the upper protective component, and a control circuit board is installed inside the protective cover. The X-axis fine-tuning compensation mechanism, Y-axis fine-tuning compensation mechanism, Z-axis fine-tuning compensation mechanism and force sensor are connected to the control circuit board to provide power for the X-axis fine-tuning compensation mechanism, Y-axis fine-tuning compensation mechanism, Z-axis fine-tuning compensation mechanism and force sensor, receive data from the X-axis fine-tuning compensation mechanism, Y-axis fine-tuning compensation mechanism, Z-axis fine-tuning compensation mechanism and force sensor, and the control circuit board is connected to the control system through signals.

[0018] In addition, the present invention also relates to a control method for an active force-controlled grinding compensation module, including the following steps: S1: Preparation work: Input the 3D data of the grinding workpiece and the elastic modulus data of the grinding consumables into the control system; Set the grinding adjustment threshold in the control system and the target pressure when the five-axis grinding machine grinds the workpiece; Input the minimum adjustment step of the compensation module into the control system, grind the workpiece multiple times, record the movement route of the compensation module, and calculate the difference between the target grinding force and the actual measurement value. Pre-train the neural network model of the relationship between the difference between the target grinding force and the actual measurement value and the movement route of the compensation module; S2: Start work: The control system reads the position data of each axis of the five-axis grinding machine through the five-axis grinding machine numerical control 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, the position data of each axis of the five-axis grinding machine and the elastic modulus data of the grinding consumables input in S1; S3: The control system calculates the target grinding force of the five-axis grinding machine according to the equivalent grinding contact area at the real-time grinding position and the target pressure when the five-axis grinding machine grinds the workpiece; S4: The control system receives the actual measurement value of the force sensor, compares it with the target grinding force, and judges whether the difference between the two falls within the pre-set grinding adjustment threshold; If it does not fall within the grinding adjustment threshold, it directly enters S2. If it falls within the grinding adjustment threshold, it enters 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 movement routes of the XYZ three axes of the compensation module; S6: The control system generates a position adjustment instruction according to the minimum adjustment step instruction and sends it to the compensation module through the EtherCAT Ethernet fieldbus for real-time adjustment of the positions of the XYZ three axes of the compensation module.

[0019] For the optimization of the technical solution of the present invention, the training method of the neural network model in S1 is as follows: the input layer receives x, uses the weight w to model the input value, each hidden layer calculates the output, and the data is ready at the output layer, that is, the movement route of the compensation module is obtained; use this neural network model to perform the position compensation of the processed workpiece for several times, use the mean square error between the output value of the movement route of the compensation module and the actually detected movement route of the compensation module as the loss function, then return to the hidden layer and adjust the weight and then perform the grinding test again to obtain the loss function value, and perform multiple iterations until the trained loss function is less than the set value, the training ends, and the trained neural network model is obtained.

[0020] The beneficial effects of the present invention compared with the prior art are as follows: 1. The control system receives the force sensor data, then calculates the adjustment distance of the entire compensation module according to the change of the actual processing area of the processed workpiece, and then controls the displacement of the X-axis fine adjustment compensation mechanism, the Y-axis fine adjustment compensation mechanism, and the Z-axis fine adjustment compensation mechanism for position compensation, so that the compensation module adapts to the processing surface with a large curvature change; 2. The compensation structure is arranged above the workpiece adjustment rotation shaft, and 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 prior art; 3. A negative pressure installation device is installed on the fixture, and the workpiece to be processed is fixed by negative pressure, reducing the situation that when the existing grinding equipment adjusts the position of the workpiece on the fixture of the compensation structure, the clamping device of the tooling contacts the grinding tool, resulting in damage to the clamping device and affecting the judgment of the grinding position of the workpiece to be processed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Shown is a three-dimensional structure schematic diagram of an active force control grinding compensation module of the present invention; Figure 2 Shown is a front view of an active force control grinding compensation module of the present invention; Figure 3 Shown is a three-dimensional structure schematic diagram of the internal structure of an active force control grinding compensation module of the present invention Figure 1 ; Figure 4 Shown is a three-dimensional structure schematic diagram of the internal structure of an active force control grinding compensation module of the present invention Figure 2 ; Figure 5 Shown is a cross-sectional view of an active force control grinding compensation module of the present invention; Figure 6 Shown is a structure schematic diagram of the lower surface of the fixture of the present invention; Figure 7 Shown is a structure schematic diagram of the upper surface of the fixture of the present invention; Figure 8The figure shows a schematic structural diagram of the Z-axis fine-tuning compensation mechanism of the present invention; Figure 9 The figure shows a schematic structural diagram of the X-axis fine-tuning compensation mechanism of the present invention; Figure 10 The figure shows a schematic control network structure diagram of the active force control grinding compensation module of the preferred embodiment of the present invention; Figure 11 The figure shows a schematic flow diagram of the control method of the active force control grinding compensation module of the preferred embodiment of the present invention.

[0022] Explanation of reference numerals: 1, workpiece adjustment rotating shaft; 2, installation 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 post and linear bearing; 6, force sensor; 7, fixture; 8, protective housing; 81, upper protective part; 82, lower protective part; 83, connecting plate; 9, protective cover; 10, detachable observation window; 11, detachable steel adapter sleeve; 12, pipeline groove; 13, quick connector; 14, negative pressure air port. Detailed implementation manners

[0023] Next, the technical solutions in the embodiments of the present invention will be described in detail in conjunction with the attached Figures 1 to 11 drawings of the embodiments of the present invention.

[0024] Embodiment

[0025] As Figures 1 to 9 shown, an active force control grinding compensation module includes a five-axis grinding machine and a workpiece adjustment rotating shaft 1, and further includes an installation 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.

[0026] Definition: Taking the original installation position of the processed workpiece on the installation plane 2 of the workpiece adjustment rotating shaft 1 as the origin, a rectangular coordinate system is set, taking the workpiece adjustment rotating shaft 1 as the C axis, the position of the fixture 7 is up, and the position of the workpiece adjustment rotating shaft 1 is down.

[0027] The workpiece adjustment rotating shaft 1 is installed on an existing five-axis grinding machine to adjust the angular position of the processed workpiece on the C axis.

[0028] The installation plane 2 of the workpiece adjustment rotating shaft 1 provides installation positions 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.

[0029] After the C-axis adjustment is completed, the X-axis fine-tuning compensation mechanism 3 fine-tunes the position of the workpiece in the X-axis, the Y-axis fine-tuning compensation mechanism 4 fine-tunes the position of the workpiece in the Y-axis, and the Z-axis fine-tuning compensation mechanism 5 fine-tunes the position of the workpiece in the Z-axis.

[0030] The fixture 7 is arranged on the Z-axis fine-tuning compensation mechanism 5 to provide a fixed position for the workpiece to be processed.

[0031] The force sensor 6 is arranged between the fixture 7 and the Z-axis fine-tuning compensation mechanism 5 to detect the actual grinding force received by the workpiece on the fixture 7.

[0032] The control system receives the data from the original five-axis grinding machine numerical control 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 to be processed.

[0033] 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, and is used for fixedly connecting the X-axis fine-tuning compensation mechanism 3 and the workpiece adjustment rotating shaft 1; The first slide rail 32 is welded on the first base 31. The first slide rail 32 includes two metal blocks with a smooth surface and an I-shaped cross-section, and is used for slidably installing the first slider 33. The first slide rail 32 is arranged in the X-axis direction of the rectangular coordinate system.

[0034] 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 a 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, so as to simultaneously fine-tune the position of the workpiece installed on the Y-axis fine-tuning compensation mechanism 4, the Z-axis fine-tuning compensation mechanism 5 and the fixture 7 in the X-axis direction.

[0035] The upper surface of the first slider 33 is fixedly connected to the Y-axis fine-tuning compensation mechanism 4 through 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.

[0036] The second base 41 is a thin metal plate with a rectangular cross-section, and is used for fixedly connecting the X-axis fine-tuning compensation mechanism 3 and the Y-axis fine-tuning compensation mechanism 4 through screws.

[0037] The second slide rail 42 is welded on 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 perpendicular to the first slide rail 32 and is set in the Y-axis direction of the rectangular coordinate system.

[0038] 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 Y-axis position of the workpiece installed on the Z-axis fine-tuning compensation mechanism 5 and the fixture 7.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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 be processed, so as to accurately and quickly measure the force applied to 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 themselves, and 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 themselves during movement on the detection result of the force sensor 6, 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 sensor with a smaller range can be selected, which in disguise improves the resolution of the sensor, thereby improving the fine-tuning compensation effect and effectively reducing costs.

[0043] The X-axis fine-tuning compensation mechanism 3, Y-axis fine-tuning compensation mechanism 4, and Z-axis fine-tuning compensation mechanism 5 use micro servo electric cylinders. The high integration effectively reduces the space occupied by the traditional servo motor with a lead screw and the lead screw fixing seat. On the first base 31, second base 41, and third base 51, there are U-shaped electric cylinder fixing seats and T-shaped electric cylinder push-pull seats fixed to their bottom plates by screws, which can provide hard limits for the fine-tuning compensation mechanism while transmitting power.

[0044] The fixture 7 is provided with a negative pressure installation device to fix the position of the grinding workpiece through negative pressure. The negative pressure installation device includes a quick connector 13, an air pipe, a negative pressure air port 14, a detachable steel adapter sleeve 11, and an air pipe. The negative pressure air port 14 is arranged on the fixture 7. The fixture 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, and the air pipe provides negative pressure for the negative pressure air port 14 to fix the workpiece on the fixture 7. Installing the negative pressure installation device on the fixture can fix the workpiece to be processed through negative pressure, reducing the situation where the clamping device in the existing grinding equipment contacts the grinding tool during grinding and causes damage to the clamping device.

[0045] The X-axis fine-tuning compensation mechanism 3, Y-axis fine-tuning compensation mechanism 4, and Z-axis fine-tuning compensation mechanism 5 are externally provided with a protective housing 8. The protective housing 8 includes an upper protective part 81 and a lower protective part 82. The upper protective part 81 is fixedly installed on the lower side of the fixture 7 through a connecting plate 83 and is a cylindrical protective metal housing. The lower protective part 82 is welded to the installation surface 2 and is a cylindrical protective metal housing with a radius smaller than that of the upper protective part 81. The protective housing 8 protects the internal structure and provides isolation protection for polishing liquid, etc. during the processing, improving the stability of equipment use.

[0046] A pipeline groove 12 is arranged inside the lower protective part 82. The power lines, network cables of the X-axis fine-tuning compensation mechanism 3, Y-axis fine-tuning compensation mechanism 4, and Z-axis fine-tuning compensation mechanism 5, and the air pipe providing negative pressure for the fixture 7 are installed and coiled several times in the pipeline groove 12 and led out from the groove opening to ensure that the remaining length of the wire routing can ensure the normal rotation of the workpiece adjustment rotating shaft 1.

[0047] A protective cover 9 is welded on the outer side of the upper protective part 81. A control circuit board is installed inside the protective cover 9 to provide power for the X-axis fine-tuning compensation mechanism 3, Y-axis fine-tuning compensation mechanism 4, Z-axis fine-tuning compensation mechanism 5, and the force sensor 6, receive data from the X-axis fine-tuning compensation mechanism 3, Y-axis fine-tuning compensation mechanism 4, Z-axis fine-tuning compensation mechanism 5, and the force sensor 6. The control circuit board is connected to the control system through a wireless signal. A detachable observation window 10 is designed on the protective cover 9, which is easy to monitor its working status display lamp and disassemble and replace.

[0048] The compensation structure is arranged above the workpiece adjustment rotating shaft 1 and does not need to drive the workpiece adjustment rotating shaft 1 to move anymore. Therefore, the overall mass of the structure that the compensation structure needs to drive is relatively small, and there is no need to have a larger and heavier overall structure to ensure the stiffness of the system. Therefore, the overall volume of the compensation module in this application is smaller than that of the prior art.

[0049] As Figures 10 to 11 shown, the control method for the active force control grinding compensation module includes the following steps: S1: Preparation work: Input the 3D data of the grinding workpiece and the elastic modulus data of the grinding consumables into the control system; Set the grinding adjustment threshold in the control system and the target pressure when the five-axis grinding machine grinds the workpiece; Input the minimum adjustment step size of the compensation module into the control system, grind the workpiece multiple times, record the movement route of the compensation module, and calculate the difference between the target grinding force and the actual measured value. Pre-train the neural network model of the relationship between the difference between the target grinding force and the actual measured value and the movement route of the compensation module; S2: Start working: The control system reads the position data of each axis of the five-axis grinding machine through the five-axis grinding machine numerical control 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, the position data of each axis of the five-axis grinding machine, and the elastic modulus data of the grinding consumables input in S1; S3: The control system calculates the target grinding force of the five-axis grinding machine according to the equivalent grinding contact area at the real-time grinding position and the target pressure when the five-axis grinding machine grinds the workpiece; S4: The control system receives the actual measured value of the force sensor, compares it with the target grinding force, and judges whether the difference between the two falls within the pre-set grinding adjustment threshold; If it does not fall within the grinding adjustment threshold, directly enter S2. If it falls within the grinding adjustment threshold, enter S5; S5: The control system inputs the difference between the actual measured value of the force sensor and the target grinding force into the neural network model trained in S1 to generate the movement route of the XYZ three axes of the compensation module; S6: The control system generates a position adjustment instruction according to the minimum adjustment step size instruction and sends it to the compensation module through the EtherCAT Ethernet fieldbus to perform real-time adjustment of the XYZ three-axis positions of the compensation module.

[0050] In this embodiment, the position compensation principle of the grinding compensation module is as follows: the equivalent grinding contact area of the real-time grinding position is calculated based on the positions of each axis read from the numerical control system of the five-axis grinding machine, the 3D data of the workpiece to be processed, and the elastic modulus data of the grinding consumables input into the control system of the grinding compensation module. Then, the equivalent grinding force at the real-time grinding position is calculated by multiplying it with the input grinding pressure command. After comparing with the actual measurement data of the force sensor and reaching the input grinding adjustment threshold command, specific adjustment commands for the three-axis fine-tuning compensation platform are generated according to the minimum adjustment step command, and finally sent to the actuator of the three-axis fine-tuning compensation platform for real-time adjustment.

[0051] In this embodiment, the control system of this module only reads the position data of each axis of the numerical control system of the original five-axis grinding machine, bypasses the numerical control system of the original five-axis grinding machine, and does not need to be integrated into the numerical control system of the original five-axis grinding machine.

[0052] In step S1 of this embodiment, the elastic modulus data of the consumables is provided by the consumables supplier and manually input into the system by the operator during the parameter setting process. The 3D data of the workpiece to be processed is provided by Party A and is the standard neural network model of the workpiece. When in use, the operator needs to manually upload the neural network model to the control system or input the dataset of the neural network model into the control system.

[0053] The grinding adjustment threshold in the control system is set by conducting multiple grinding tests on a type of workpiece to obtain the data of the grinding effect, the actual measurement value of the force sensor, and the target grinding force during multiple grindings. 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.

[0054] The target pressure when the five-axis grinding machine grinds the workpiece is the input value entered by the user at the input end of the control system.

[0055] The minimum adjustment step length of the compensation module is input into the control system. The minimum adjustment step lengths of the X-axis, Y-axis, and Z-axis are set values manually input. The adjustment distance in the single-axis direction for each control cycle is the minimum adjustment step length, and the minimum adjustment step length can be 0.01 cm.

[0056] Based on multiple measurement results, 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 route of the compensation module is pre-trained, where the actual movement route of the compensation module is obtained by copying the tool path of the workpiece.

[0057] The training method of the neural network model in S1 is as follows: The input layer receives x, uses the weight w to model the input value, each hidden layer calculates the output, and the data is ready at the output layer, that is, the movement route of the compensation module is obtained; Use this neural network model to perform several workpiece position compensations. The x received by the input layer is the difference between the actual movement route of the compensation module and the actual measured value of the force sensor of the target grinding force. The mean square error between the output value of the movement route of the compensation module and the actual detected movement route of the compensation module is used as the loss function, and then it returns to the hidden layer and adjusts the weights and then performs the grinding test again to obtain the loss function value. After multiple iterations, until the trained loss function is less than the set value, the training ends, and a trained neural network model is obtained.

[0058] In the pre-run process, first, the compensation module does not work. Adjust the five-axis grinding machine until the value of the force sensor is the target grinding force, and observe the grinding effect. Then start the compensation module to fine-tune the workpiece, record the data of the force sensor as the actual measured value of the force sensor, and the change of the grinding effect. According to the change range of the grinding effect, record the data of the force sensor as the range of the actual measured value of the force sensor. The difference between the actual measured value of the force sensor and the target grinding force is used as the grinding adjustment threshold.

[0059] During the fine-tuning process of the compensation module, a profiling feed is performed on the workpiece to obtain the movement route of the compensation module, and a neural network model of the relationship between the difference between the target grinding force and the actual measured value of the force sensor and the movement route of the compensation module is trained in combination with the change of the difference between the target grinding force and the actual measured value of the force sensor.

[0060] In this implementation method, a neural network model of the relationship between the difference between the target grinding force and the actual measured value of the force sensor and the movement route of the compensation module is trained in advance, which is convenient for the system to quickly calculate the movement route of the compensation module and reduce the hysteresis of the compensation module.

[0061] In step S2 of this embodiment, the control system reads the position data of each axis of the five-axis grinding machine through the five-axis grinding machine numerical control system, and calculates the position change amount of the workpiece according to the 3D data of the workpiece input in S1 and the position data of each axis of the five-axis grinding machine.

[0062] The position change amount of the workpiece, the elastic modulus data of the grinding consumables, and the position change amounts of different elastic modulus grinding consumables with the pre-detected grinding contact area under force are compared and calculated to obtain the area at the same stress, and the equivalent grinding contact area of the workpiece at the real-time grinding position is obtained.

[0063] In step S3 of this embodiment, the control system calculates the target grinding force of the five-axis grinding machine according to the equivalent grinding contact area at the real-time grinding position and the target pressure when the five-axis grinding machine grinds the workpiece.

[0064] The target grinding force is the product of the equivalent grinding contact area and the target pressure.

[0065] 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 the preset grinding adjustment threshold. If it does not fall within the grinding adjustment threshold, it directly enters S2. If it falls within the grinding adjustment threshold, it enters S5. 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 indicates that the grinding effect is good. Therefore, no position fine-tuning is required, and after the grinding angle of the workpiece to be processed is changed, it re-enters 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 to be processed is poor, and the compensation module needs to fine-tune the position of the workpiece.

[0066] 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 difference between the target grinding force and the actual measurement value of the force sensor trained in S1 to generate the movement routes of the X, Y, and Z axes of the compensation module. As the number of grinding times increases, the 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 of the compensation module will become more and more accurate.

[0067] In step S6 of this embodiment, the control system generates a position adjustment command according to the minimum adjustment step command and sends it to the compensation module through the EtherCAT Ethernet fieldbus to perform real-time adjustment of the positions of the X, Y, and Z axes of the compensation module, optimizing the grinding efficiency of the grinding machine.

[0068] This structure is intuitive and easy to operate. It can perform fine-tuning compensation on multiple workstations in the same five-axis grinding special machine with different parameter settings respectively, so as to perform process tests with different parameters faster. Moreover, this structure is easy to expand workstations and has good adaptability and economy for different numbers of workstations in different situations.

[0069] The control system also includes a screen for interactive display located outside the five-axis grinding special machine, or accesses the control screen of the original grinding special machine. Only a power cord and an eight-core network cable need to be introduced from the outside into its internal part, which is transferred by a ten-core waterproof aviation plug, ensuring the safety and reliability of its protection.

[0070] Through the above control method of the grinding compensation module, the equivalent area and equivalent grinding force of curved surfaces with different curvatures are calculated, compared with the force values measured by the sensor, and the three-axis platform performs fine-tuning compensation to achieve the grinding effect of constant pressure; different parameters such as pressure, adjustment threshold, and adjustment step can be applied to multiple workstations for simultaneous processing, making the exploration of process parameters and the collection of data more convenient and fast, etc.

[0071] The above embodiments are only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the present invention.

Claims

1. An active force control grinding compensation module, comprising a five-axis grinding machine and a workpiece adjusting and rotating shaft (1), characterized in that: It also includes an installation 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 installed 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 installed in sequence on the installation plane (2) of the workpiece adjustment rotating shaft (1) 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 install the grinding workpiece. The fixture (7) is provided with a negative-pressure installation device including a quick connector (13), an air pipe, and a negative-pressure air port (14). The negative-pressure air port (14) is arranged 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) to fix the grinding workpiece by 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 received by the grinding workpiece and the fixture (7). The control system controls the five-axis grinding machine, 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.

2. The active force control grinding compensation module according to claim 1, wherein: 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 fixedly installed on the installation plane (2) of the workpiece adjustment rotating shaft (1). A first slide rail (32) is arranged on the first base (31). The first micro servo electric cylinder (34) is installed on the surface of the first base (31) to drive the first slider (33) to move on the first slide rail (32). The first slide rail (32) is connected to the Y-axis fine-tuning compensation mechanism (4) through the first slider (33).

3. The active force control grinding compensation module according to claim 2, characterized in that: 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). The second base (41) is fixedly connected to the first slider (33). The second slide rail (42) is fixedly connected to the surface of the second base (41) and is perpendicular to the first slide rail (32). The second slide rail (42) is slidably connected to the second slider (43). The 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). The Z-axis fine-tuning compensation mechanism (5) is fixedly connected to the second slider (43).

4. The active force control grinding compensation module according to claim 3, wherein: The Z-axis fine-tuning compensation mechanism (5) includes a third base (51), a third micro servo electric cylinder (52), a guide post, and a linear bearing (53). The third base (51) is fixedly connected above the second slider (43). A guide post and a linear bearing (53) are provided at each of 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 jig (7) through the third micro servo electric cylinder (52), and the third micro servo electric cylinder (52) drives the jig (7) to displace.

5. The active force control grinding compensation module according to claim 1, characterized in that: 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 externally provided with a protective housing (8). The protective housing (8) includes an upper protective component (81) and a lower protective component (82). The upper protective component (81) is fixedly installed on the lower side of the jig (7) through a connecting plate (83), and the lower protective component (82) is fixedly connected to the installation plane (2).

6. The active force control grinding compensation module according to claim 5, wherein: A pipeline groove (12) is provided inside the lower protective component (82). The power lines, 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 the negative pressure installation device that provides negative pressure for the jig (7) are installed in the pipeline groove (12).

7. The active force control grinding compensation module according to claim 5, wherein: A protective cover (9) is provided on the outer side of the upper protective component (81). 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 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), 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 a signal.

8. A control method for an active force control grinding compensation module according to any one of claims 1 to 7, characterized in that, It includes the following steps: S1: Preparation work: Input the 3D data of the workpiece to be polished and the elastic modulus data of the polishing consumables into the control system; Set the polishing adjustment threshold in the control system and the target pressure when the five-axis polishing machine polishes the workpiece; Input the minimum adjustment step of the compensation module into the control system. Polish the workpiece multiple times, record the movement route of the compensation module, and calculate the difference between the target polishing force and the actual measured value. Pre-train the neural network model of the relationship between the difference between the target polishing force and the actual measured value and the movement route of the compensation module; S2: Start work: The control system reads the position data of each axis of the five-axis polishing machine through the five-axis polishing machine numerical control system, and obtains the equivalent polishing contact area of the workpiece at the real-time polishing position according to the 3D data of the workpiece, the position data of each axis of the five-axis polishing machine, and the elastic modulus data of the polishing consumables input in S1; S3: The control system calculates the target polishing force of the five-axis polishing machine according to the equivalent polishing contact area at the real-time polishing position and the target pressure when the five-axis polishing machine polishes the workpiece; S4: The control system receives the actual measured value of the force sensor, compares it with the target polishing force, and judges whether the difference between the two falls within the preset polishing adjustment threshold; If it does not fall within the grinding adjustment threshold, it directly enters S2. If it falls within the grinding adjustment threshold, it enters S5; S5: The control system inputs the difference between the actual measured value of the force sensor and the target grinding force into the neural network model trained in S1 to generate the movement routes of the XYZ axes of the compensation module; S6: The control system generates a position adjustment command according to the minimum adjustment step size command and sends it to the compensation module through the EtherCAT Ethernet fieldbus for real-time adjustment of the positions of the XYZ axes of the compensation module.

9. The control method of an active force control grinding compensation module according to claim 8, characterized in that, The training method of the neural network model in S1 is as follows: The input layer receives x, uses the weight w to model the input value, each hidden layer calculates the output, and the data is ready at the output layer, that is, the movement route of the compensation module is obtained; Use this neural network model to perform position compensation for the workpiece to be processed several times. Take the mean square error between the output value of the movement route of the compensation module and the actually detected movement route of the compensation module as the loss function, then return to the hidden layer and adjust the weights, and then perform the grinding test again to obtain the loss function value. Perform multiple iterations until the loss function after training is less than the set value, and the training ends to obtain the trained neural network model.

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