Force-controlled grinding device and control method thereof, grinding robot and control method thereof

Abstract

The present invention relates to a force-controlled grinding device and a control method thereof, a grinding robot and a control method thereof, comprising a housing, wherein the housing is provided with: a transmission assembly, the transmission assembly comprising a spline spindle, a spline nut and a bearing seat, the spline nut being sleeved on the spline end of the spline spindle, the spline nut being matched with the bearing seat; a grinding head, the grinding head being connected to the spline spindle; a rotary drive source, the rotary drive source driving the spline spindle to rotate around its axial direction; a translation drive assembly, the translation drive assembly comprising a hydraulic motor and a first mounting seat, the first mounting seat being fixedly connected to the spline spindle, the hydraulic motor driving the first mounting seat to move axially along the spline spindle; a tension pressure sensor, which is used to monitor the pressure of the grinding head on the workpiece, the tension pressure sensor being located between the first mounting seat and the spline spindle. Active flexible grinding is achieved, and the device has low cost, high grinding precision, good flexible adaptability, simple operation and low grinding noise.

Description

Technical Field

[0001] The present invention relates to the technical field of polishing, and in particular to a force-controlled polishing device and a control method thereof, a polishing robot and a control method thereof. Background Art

[0002] To meet workpiece surface accuracy and roughness requirements, grinding and polishing processes are incorporated into the production process and are crucial for ensuring workpiece quality. As one of the most common production processes in the manufacturing industry, many companies still rely on manual labor for grinding and polishing. These problems, such as low efficiency, high defect rates, and uneven workpiece surface roughness, remain unresolved. During grinding, the contact between the grinding head and the workpiece generates force, and the magnitude of this contact force is a key factor influencing grinding quality. When grinding rigid workpieces, even a slight displacement of the grinding head can generate significant force. Excessive force can affect workpiece quality and even damage the grinding head and drive mechanism. Low force can prevent contact between the grinding head and the workpiece, resulting in substandard grinding quality or incomplete polishing, leading to missed polishing spots. To ensure workpiece quality and the safe operation of the grinding head and drive mechanism, the force between the grinding head and the workpiece must be quickly and accurately controlled to maintain a constant level. Currently, force-controlled grinding systems typically utilize two approaches: a multi-dimensional sensor mounted on the end of the robot, or a one-dimensional force sensor mounted on the end of the grinding tool. During robot grinding operations for workpieces with good appearances, the machining error between the robot end and the workpiece can be controlled within a certain range by planning a precise motion trajectory, thereby keeping the contact force between the robot and the workpiece within a certain range. In actual production, the workpieces to be ground are often irregular, causing the robot to generate additional forces when moving according to the theoretical trajectory. If the additional forces generated cannot be quickly eliminated, the grinding effect of the workpiece will be affected. Although robot technology is relatively mature, it is difficult to achieve fast and accurate constant force control. Developing a fast and accurate constant force grinding system is a difficult problem in the grinding industry.

[0003] With the increasing cost of labor, all walks of life are facing a shortage of workers, especially the heavy industry, which is seeking automated solutions to replace manual labor. Typical areas such as welding, 3D printing, and castings are in urgent need of robotic automated grinding. However, the structural characteristics of welding, additive manufacturing, castings, etc. are complex and non-standard, and the requirements for different materials, surface shapes, and surface roughness are different. Automated grinding has always been a difficulty and pain point in the heavy industry. There are also some grinding equipment on the market, mainly electric spindles and pneumatic spindles, equipped with laser vision sensors, six-dimensional force control equipment, etc. The equipment on the market has the following problems: (1) The price is relatively high; (2) The appearance consistency after grinding is not good; (3) The flexibility and adaptability are poor, the operation is complicated, and the grinding noise is loud; (4) Pneumatic grinding requires an external air source; (5) The grinding tools are heavy and need to be equipped with heavy-duty robots. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the technical defects of the prior art grinding device that is not suitable for irregular workpieces and cannot achieve active constant force grinding.

[0005] In order to solve the above technical problems, the present invention provides a force-controlled grinding device, comprising a housing, wherein the housing is provided with:

[0006] A transmission assembly, comprising a spline main shaft, a spline nut and a bearing seat, wherein the spline nut is sleeved on the spline end of the spline main shaft, and the spline nut is arranged in cooperation with the bearing seat;

[0007] A grinding head, which is used for grinding a workpiece, and the grinding head is connected to the spline spindle;

[0008] a rotational drive source, wherein the rotational drive source drives the spline main shaft to rotate about its axial direction, the rotation of the spline main shaft drives the spline nut to rotate synchronously, and the bearing seat limits the motion of the spline nut;

[0009] A translation drive assembly, the translation drive assembly comprising a hydraulic motor and a first mounting seat, the first mounting seat being fixedly connected to the spline spindle, the hydraulic motor driving the first mounting seat to move axially along the spline spindle, and the movement of the spline spindle drives the grinding head to move closer to or away from the workpiece;

[0010] The tension pressure sensor is used to monitor the pressure of the grinding head on the workpiece, and the tension pressure sensor is located between the first mounting seat and the spline spindle.

[0011] Preferably, the rotational drive source is a servo motor, and a sliding coupling is provided between the servo motor and the spline spindle. The servo motor transmits torque to the spline spindle through the sliding coupling. The sliding coupling allows the spline spindle to float along its axial direction, thereby reducing the influence of friction on the reaction force measured by the compression and tension sensors.

[0012] Preferably, the slidable coupling comprises:

[0013] a first cover and a second cover, wherein the first cover and the second cover cooperate to hold the output shaft of the servo sensor;

[0014] A first rolling assembly and a second rolling assembly are respectively provided on the first cover body and the second cover body, the first rolling assembly includes a first rotating shaft and a first needle roller bearing arranged in cooperation with the first rotating shaft, the first rotating shaft is fixed to the first cover body, the second rolling assembly includes a second rotating shaft and a second needle roller bearing arranged in cooperation with the second rotating shaft, the second rotating shaft is fixed to the second cover body, the first needle roller bearing and the second needle roller bearing are respectively located on both sides of the spline main shaft, and the spline main shaft is flat.

[0015] Preferably, the portion of the splined spindle extending out of the housing is sealed with a rubber ring to isolate it from dust.

[0016] Preferably, the spline spindle is detachably connected to the grinding head.

[0017] Preferably, a dust cover is provided between the bearing seat and the first mounting seat, and the dust cover is sleeved on the outside of the spline main shaft.

[0018] Preferably, an angular contact ball bearing is provided between the first mounting seat and the spline main shaft.

[0019] The present invention discloses a control method for a force-controlled grinding device, based on the above-mentioned grinding device, comprising the following steps:

[0020] S1. Obtain the set value of the grinding force;

[0021] S2. The tension and pressure sensor detects in real time the current grinding force, wherein the current grinding force is the pressure exerted by the grinding head on the workpiece, which is obtained by the tension and pressure sensor detecting the tension and pressure exerted by the spline spindle on the workpiece;

[0022] S3. Comparing the current grinding force with a set value; when the current grinding force is greater than the set value, the hydraulic motor reduces the movement stroke of the output shaft to ensure constant force output of the grinding head; when the current grinding force is less than the set value, the hydraulic motor increases the movement stroke of the output shaft to ensure constant force output of the grinding head;

[0023] The hydraulic motor has a built-in displacement sensor to detect and correct the displacement of the output shaft of the hydraulic motor in real time.

[0024] The invention discloses a polishing robot, comprising a multi-axis manipulator, on which the force-controlled polishing device is installed.

[0025] The present invention discloses a control method for a polishing robot. Based on the above-mentioned polishing robot, the control method comprises the following steps:

[0026] S1. Obtain the set value of the grinding force;

[0027] S2. The tension and pressure sensor detects in real time the current grinding force, wherein the current grinding force is the pressure exerted by the grinding head on the workpiece, which is obtained by the tension and pressure sensor detecting the tension and pressure exerted by the spline spindle on the workpiece;

[0028] S3, compare the current grinding force with the set value;

[0029] When the current grinding force is greater than the set value, and the difference between the current grinding force and the set value is greater than a preset threshold, the multi-axis manipulator drives the power-controlled grinding device to move away from the workpiece to reduce the grinding force;

[0030] When the current grinding force is greater than a set value, and the difference between the current grinding force and the set value is less than a preset threshold, the hydraulic motor reduces the movement stroke of the output shaft to ensure a constant force output of the grinding head;

[0031] When the current grinding force is less than a set value, and the difference between the set value and the current grinding force is greater than a preset threshold, the multi-axis manipulator drives the power-controlled grinding device to move toward the workpiece to increase the grinding force;

[0032] When the current grinding force is less than the set value, and the difference between the set value and the current grinding force is less than a preset threshold, the hydraulic motor increases the movement stroke of the output shaft to ensure constant force output of the grinding head.

[0033] The force-controlled grinding device of the present invention has the following advantages over the prior art:

[0034] 1. The present invention drives the spline spindle to translate through a hydraulic motor, thereby driving the grinding head to approach or move away from the workpiece, and the rotary drive source drives the spline spindle to rotate, thereby realizing the rotation of the grinding head and facilitating the grinding of the workpiece.

[0035] 2. In the present invention, the spline nut can rotate at high speed to provide the grinding head with the torque and speed required for grinding.

[0036] 3. In the present invention, the hydraulic motor overcomes the reaction force of the workpiece on the grinding tool, ensures the consistency of the pressure on the workpiece during grinding through its own floating, and implements feedback of the grinding pressure through the pulling pressure sensor, thereby improving the grinding accuracy and achieving constant force output.

[0037] 4. The grinding device of the present invention can adapt to irregular workpieces and realize active flexible grinding. It has low cost, high grinding precision, good flexible adaptability, simple operation, low grinding noise, no need for external air source, and compact structure.

[0038] The control method of the force-controlled grinding device of the present invention has the following advantages over the prior art:

[0039] 1. The present invention detects the current grinding force through a tension and pressure sensor, compares the current grinding force with the set value, and adjusts the movement stroke of the spline spindle through a hydraulic sensor to achieve constant force output.

[0040] 2. The hydraulic motor of the present invention has a built-in displacement sensor, which facilitates real-time detection and correction of the displacement of the output shaft of the hydraulic motor.

[0041] The polishing robot of the present invention has the following advantages over the prior art:

[0042] 1. The present invention uses a multi-axis manipulator to drive the power-controlled grinding device to move in the area of ​​the workpiece to be ground. It is suitable for irregular workpieces, has good flexibility and adaptability, is easy to operate, and has low grinding noise.

[0043] 2. In the present invention, when the tension and pressure sensor detects that the current grinding force exceeds a certain range, the multi-axis manipulator can compensate for the movement of the grinding head and adjust the grinding head to within the movement range that can be controlled by the hydraulic motor. That is, the multi-axis manipulator realizes the large stroke adjustment of the grinding head, and the hydraulic motor realizes the small stroke adjustment of the grinding head. Through the cooperation of the multi-axis manipulator and the hydraulic motor, constant force grinding can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0045] Figure 1 Schematic diagram of the structure of the force-controlled grinding device of the present invention;

[0046] Figure 2 This is a schematic diagram of the structure of the force-controlled grinding device of the present invention with the housing removed;

[0047] Figure 3 is a cross-sectional view of the force-controlled grinding device of the present invention;

[0048] Figure 4 It is a structural diagram of the coupling, splined main shaft and bearing seat;

[0049] Figure 5 for Figure 4 sectional view of

[0050] Figure 6 This is a schematic diagram of the structure of a force-controlled grinding device for grinding workpieces.

[0051] Explanation of the reference numerals in the specification: 10. Housing; 11. Mounting plate; 20. Grinding head; 30. First mounting seat; 31. Tensile pressure sensor; 32. Angular contact ball bearing; 40. Hydraulic motor; 41. Push plate; 50. Rotary drive source; 60. Slidable coupling; 61. First cover; 62. Second cover; 63. First needle roller bearing; 64. Second needle roller bearing; 65. First rotating shaft; 66. Second rotating shaft; 70. Bearing seat; 80. Spline spindle; 81. Spline nut; 90. Linear guide; 91. Dust cover. DETAILED DESCRIPTION

[0052] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0053] Reference Figures 1-6 As shown, the present invention discloses a force-controlled grinding device, which includes a housing 10 , in which a transmission assembly, a grinding head 20 , a rotation drive source 50 and a translation drive assembly are arranged.

[0054] The transmission assembly includes a splined spindle 80, a splined nut 81, and a bearing seat 70. The splined nut 81 is mounted on the splined end of the splined spindle 80. Because the splined nut 81 cooperates with the splined spindle 80, when the splined spindle 80 rotates, the splined nut 81 rotates synchronously with the splined spindle 80. The bearing seat 70 limits the splined nut 81, preventing it from moving axially. At the same time, because the splined nut cooperates with the splined nut 81 through the spline, the splined spindle 80 can also move axially relative to the splined nut 81.

[0055] The grinding head 20 is used for grinding a workpiece. The grinding head 20 is connected to the spline spindle 80 . Thus, the movement of the spline spindle 80 drives the grinding head 20 to move.

[0056] The rotation driving source 50 drives the spline main shaft 80 to rotate around its axial direction. The spline nut 81 rotates to drive the spline main shaft 80 to rotate synchronously, thereby driving the grinding head 20 to rotate.

[0057] The translation drive assembly includes a hydraulic motor 40 and a first mounting seat 30. The first mounting seat 30 is fixedly connected to the spline spindle 80. The hydraulic motor 40 drives the first mounting seat 30 to move axially along the spline spindle 80. The spline spindle 80 moves to drive the grinding head 20 to approach or move away from the workpiece.

[0058] The tension pressure sensor 31 is used to monitor the pressure of the grinding head 20 on the workpiece. The tension pressure sensor 31 is located between the first mounting seat 30 and the spline spindle 80 .

[0059] The working principle of the present invention is: the hydraulic motor 40 drives the spline spindle 80 to translate, thereby driving the grinding head 20 to approach or move away from the workpiece, and the rotary drive source 50 drives the spline spindle 80 to rotate, thereby realizing the rotation of the grinding head 20, which is convenient for grinding the workpiece. Among them, the spline nut 81 can rotate at high speed to provide the grinding head 20 with the torque and speed required for grinding. In the present invention, the hydraulic motor 40 overcomes the reaction force of the workpiece on the grinding tool, ensures the consistency of the pressure on the workpiece during grinding through its own floating, and implements feedback of the grinding pressure through the pull pressure sensor 31, thereby improving the grinding accuracy and achieving constant force output. The grinding device in the present invention can adapt to irregular workpieces and realize active flexible grinding. It has low cost, high grinding accuracy, good flexible adaptability, simple operation, low grinding noise, does not require an external air source, and has a compact and exquisite structure.

[0060] The rotary drive source 50 is a servo motor. A slidable coupling 60 is interposed between the servo motor and the splined spindle 80. The servo motor transmits torque to the splined spindle 80 via the slidable coupling 60, which allows the splined spindle 80 to float axially. While the slidable coupling 60 securely holds the servo motor's output shaft, the splined spindle 80 is able to float relative to the servo motor. This reduces the effect of friction on the reaction force measured by the tension and pressure sensor 31.

[0061] The slidable coupling 60 includes a first cover 61 and a second cover 62, which cooperate to securely hold the output shaft of the servo sensor. A first rolling assembly and a second rolling assembly are disposed on the first and second covers 61 and 62, respectively. The first rolling assembly includes a first rotating shaft 65 and a first needle roller bearing 63 cooperating with the first rotating shaft 65, which is fixed to the first cover 61. The second rolling assembly includes a second rotating shaft 66 and a second needle roller bearing 64 cooperating with the second rotating shaft 66, which is fixed to the second cover 62. The first and second needle roller bearings 63 and 64 are located on either side of a flat splined main shaft 80. In the present invention, since the spline main shaft 80 is flat, due to the cooperation of the first rolling assembly and the second rolling assembly, when the spline main shaft 80 floats during operation, it rolls relative to the needle bearing to generate rolling friction, so that the influence of friction on the entire force measuring system is reduced to a minimum, the measured reaction force is more accurate, and the grinding quality is improved.

[0062] Specifically, the first cover 61 and the second cover 62 are locked by screws, so that the first cover 61 and the second cover 62 hold the output shaft of the servo motor tightly. A keyway is set on the first cover 61 or the second cover of the coupling to match the key of the servo motor output shaft. In this way, torque can be better transmitted and slippage can be avoided. The first rotating shaft 65 corresponding to the first needle roller bearing 63 is fixed to the first cover 61 by screws, and the second rotating shaft 66 corresponding to the second needle roller bearing 64 is fixed to the second cover 62 by screws. The end of the spline main shaft 80 is flattened and inserted between the two needle rollers and Zoucheng. The torque of the servo motor is transmitted to the spline main shaft through the needle roller bearings. When the spline main shaft floats during operation, it rolls relative to the needle roller bearings to generate rolling friction. The sliding coupling 60 and the spline main shaft 80 in the present invention are rolling friction, and the friction generated is small, which is suitable for high-speed rotation.

[0063] The operating principle of the grinding device with a sliding coupling 60 is as follows: The sliding coupling 60 is clamped onto the output shaft of the servo motor. During operation, the servo motor drives the sliding coupling 60 to rotate, which in turn drives the spline spindle 80 to rotate. The grinding head 20, mounted on the spline spindle 80, rotates together with the spline spindle 80 to begin normal operation. The spline nut 81 is mounted on a bearing inside the bearing seat 70. During operation, the spline spindle 80 drives the ball spline nut 81 to rotate within the bearing seat 70. The bearing seat 70 acts as a guide for the high-speed rotation of the spline spindle 80. When the grinding head 20 floats, the spline spindle 80 can slide linearly relative to the spline nut 81. When the spline nut 81 is a ball spline nut, rolling friction occurs between the two, resulting in minimal friction, allowing the tension and pressure sensor 31 to more accurately detect the reaction force during grinding.

[0064] In the present invention, the sliding coupling 60 uses a needle bearing, and the tail end of the spline main shaft 80 connected to the sliding end is designed to be flat and inserted between the two needle bearings, which reduces the coaxiality requirements between the spline main shaft and the servo motor during installation. In the prior art, most sliding couplings are sliding friction, which can only adapt to low speeds and cannot adapt to high speeds. The sliding coupling in the present invention is rolling friction, with low friction and good stability. The sliding coupling solves the problem that traditional couplings can only transmit torque but cannot make the shaft float, and solves the problem of high friction of ordinary spline telescopic couplings. It is applicable to industries such as grinding that require high force control precision. The external dimensions are smaller than traditional couplings. Based on the bearing capacity of needle bearings, the sliding coupling can transmit large torque.

[0065] In the present invention, the following two forces have a great influence on the reaction force detected by the pulling and pressure sensor 31 of the grinding equipment during grinding: one is the friction force between the ball spline nut 81 and the spline main shaft 80, and the other is the friction force between the sliding coupling 60 and the spline main shaft 80; both are rolling friction forces, and the force values ​​are relatively small. The numerical range of the force can be calculated according to the rolling friction coefficient, which is convenient for shielding during use. The pulling and pressure sensor 31 can more accurately feedback the reaction force during grinding.

[0066] The purpose of the spline nut 81 is to enable both transmission and sliding. The spline tooth profile is not limited to six, four, or two teeth. However, the sliding friction coefficient between the spline spindle 80 and the spline nut 81 must be very low. This friction coefficient affects the force measurement accuracy of the tension and pressure sensor 31 and the overall grinding effect of the grinding tool. After the two are assembled, they are lubricated with grease or oil, or other lubricating methods can be used to ensure the lowest possible friction coefficient between them.

[0067] Force-controlled floating grinding equipment operates in a harsh grinding environment, where dust, splashing, and iron filings are unavoidable. Once these impurities enter the equipment, they can affect the lifespan, precision, and friction of bearings, guide rails, and splines. This can lead to increased frictional resistance, inaccurate force control, and poor grinding results. To ensure grinding effectiveness and extend the equipment's service life, the entire device is enclosed within a housing 10. The portion of the splined spindle 80 extending beyond the housing 10 is sealed with a rubber ring, isolating most dust and impurities from entering the mechanism and affecting normal operation, thereby extending the device's service life.

[0068] The housing 10 is also provided with a mounting plate 11, which is connected to the transition plate by bolts, and the transition plate is connected to the equipment by bolts; the transition plate is required when the equipment is installed on the robot flange and the force-controlled floating grinding equipment is required to be concentric with the sixth axis of the robot. In other cases, the equipment can also be directly connected through the transition plate. The use of the equipment can be equipped with different auxiliary equipment according to the needs of the scene. For example, for workpieces of the same specification that are transported and polished through a conveyor line, they can be directly fixed on the frame, and the conveyed workpieces can be continuously rotated to grind and polish. The equipment has a small size and can meet the use requirements of different working conditions such as robots, three-axis trusses, single-axis robot AGVs and other mechanisms (hereinafter referred to as external motion mechanisms). If used in conjunction with AGV, wireless operation of the grinding equipment can be achieved, and full coverage operations can be achieved at any location.

[0069] A push plate 41 is provided at the power output end of the hydraulic motor 40 , and the push plate 41 is fixed to the first mounting seat 30 . Thus, the spline main shaft 80 can be moved by driving the first mounting seat 30 .

[0070] The force-controlled floating grinding device can be used as a standard tool and can be installed on robots, three-axis trusses, single-axis robots, etc. through the mounting plate 11 or the device body to meet the requirements of different locations.

[0071] A linear guide 90 is provided between the first mounting base 30 and the housing 10. This ensures linear floating of the grinding head 20, thereby supporting the forces generated in various directions during operation. The splined spindle 80 and splined nut 81 transmit torque while maintaining floating motion. The splined nut 81 is constructed of a wear-resistant material, such as copper alloy or manganese alloy, to ensure longevity and reduce friction between the splined spindle 80 and the splined nut 81.

[0072] The spline spindle 80 is detachably connected to the grinding head 20. For example, the spline spindle 80 and the grinding head 20 can be clamped or screwed.

[0073] A bearing seat 70 is provided in the housing 10 , and a spline nut 81 is mounted on the bearing seat 70 ; a dust cover 91 is also provided between the bearing seat 70 and the first mounting seat 30 , and the dust cover 91 is sleeved on the outside of the spline main shaft 80 .

[0074] An angular contact ball bearing 32 is positioned between the first mounting seat 30 and the splined spindle 80. The bearing can withstand the radial and axial forces generated during the grinding process. The bearing is self-sealing to prevent foreign matter and dust from entering and affecting precision.

[0075] The present invention discloses a control method for a force-controlled grinding device, based on the above-mentioned grinding device, comprising the following steps:

[0076] S1. Obtain the set value of the grinding force.

[0077] S2. The tension and pressure sensor 31 detects in real time the current grinding force, wherein the current grinding force is the pressure of the grinding head 20 on the workpiece, and the pressure of the grinding head 20 on the workpiece is obtained by the tension and pressure sensor 31 detecting the tension and pressure of the spline spindle 80 on it.

[0078] S3. Compare the current grinding force with the set value. When the current grinding force is greater than the set value, the hydraulic motor 40 reduces the movement stroke of the output shaft to ensure constant force output of the grinding head 20; when the current grinding force is less than the set value, the hydraulic motor 40 increases the movement stroke of the output shaft to ensure constant force output of the grinding head 20.

[0079] The hydraulic motor 40 has a built-in displacement sensor to detect and correct the displacement of the output shaft of the hydraulic motor 40 in real time.

[0080] The invention discloses a polishing robot, comprising a multi-axis manipulator, on which the force-controlled polishing device is installed.

[0081] The present invention discloses a control method for a polishing robot. Based on the above-mentioned polishing robot, the control method comprises the following steps:

[0082] S1. Obtain the set value of the grinding force.

[0083] S2. The tension and pressure sensor 31 detects in real time the current grinding force, wherein the current grinding force is the pressure of the grinding head 20 on the workpiece, and the pressure of the grinding head 20 on the workpiece is obtained by the tension and pressure sensor 31 detecting the tension and pressure of the spline spindle 80 on it.

[0084] S3. Compare the current grinding force with the set value.

[0085] When the current grinding force is greater than the set value, and the difference between the current grinding force and the set value is greater than a preset threshold, the multi-axis manipulator drives the power-controlled grinding device to move away from the workpiece to reduce the grinding force.

[0086] When the current grinding force is greater than the set value and the difference between the current grinding force and the set value is less than a preset threshold, the hydraulic motor 40 reduces the movement stroke of the output shaft to ensure constant force output of the grinding head 20 .

[0087] When the current grinding force is less than the set value, and the difference between the set value and the current grinding force is greater than a preset threshold, the multi-axis manipulator drives the power-controlled grinding device to move toward the workpiece to increase the grinding force.

[0088] When the current grinding force is less than the set value, and the difference between the set value and the current grinding force is less than a preset threshold, the hydraulic motor 40 increases the movement stroke of the output shaft to ensure constant force output of the grinding head 20 .

[0089] Specifically, the grinding head 20 rotates at high speed driven by a servo motor, and the force-controlled floating grinding device contacts the workpiece to be ground under the drive of an external motion mechanism (a robot, a three-axis truss, a single-axis robot, a multi-axis manipulator, etc. hereinafter referred to as an external motion mechanism). The pressure of the grinding head 20 on the workpiece is monitored by the pull pressure sensor 31 to ensure that the pressure is within a preset force value. The workpiece to be ground is ground according to the grinding process. Since the workpiece is not a regular plane, the grinding head 20 compensates for the height difference within the floating range of the grinding device. When the distance difference is too large and exceeds the compensation range of the grinding device, an external motion mechanism is required to compensate. When grinding irregular surfaces with small height differences, the motion accuracy requirements of the external motion mechanism are relatively loose.

[0090] The grinding head 20 is not only suitable for downward grinding, but also for a wide range of grinding conditions, including vertical grinding, angled grinding, and upward grinding. To accommodate grinding in various postures, a tension and pressure sensor 31 is provided to compensate for the weight of the grinding tool and the floating guide mechanism of the grinding head 20. This eliminates the influence of the equipment's own gravity and the friction of the motion mechanism on the force measurement system, making force measurement more accurate.

[0091] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0092] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0093] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0094] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0095] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A force-controlled grinding device, characterized in that: The invention comprises a housing, wherein the housing is provided with: A transmission assembly, the transmission assembly comprising a spline main shaft, a spline nut and a bearing seat, the spline nut being sleeved on the spline end of the spline main shaft, the spline nut being matched with the bearing seat, and the spline main shaft being flat; A grinding head, which is used for grinding a workpiece, and the grinding head is connected to the spline spindle; a rotational drive source, wherein the rotational drive source drives the spline main shaft to rotate about its axial direction, and the rotation of the spline main shaft drives the spline nut to rotate synchronously, and the bearing seat limits the motion of the spline nut; the rotational drive source is a servo motor; a slidable coupling is provided between the servo motor and the spline main shaft; the servo motor transmits torque to the spline main shaft through the slidable coupling; the slidable coupling allows the spline main shaft to float along its axial direction, thereby reducing the influence of friction on the reaction force measured by the compression and tension force sensor; the slidable coupling includes a first cover body and a second cover body, the first cover body and the second cover body cooperate to clamp the output shaft of the servo sensor; the first cover body and the second cover body are respectively provided with a first rolling assembly and a second rolling assembly, the first rolling assembly includes a first rotating shaft and a first needle roller bearing arranged with the first rotating shaft, the first rotating shaft is fixed to the first cover body, the second rolling assembly includes a second rotating shaft and a second needle roller bearing arranged with the second rotating shaft, the second rotating shaft is fixed to the second cover body, and the first needle roller bearing and the second needle roller bearing are respectively located on both sides of the spline main shaft; A translation drive assembly, the translation drive assembly comprising a hydraulic motor and a first mounting seat, the first mounting seat being fixedly connected to the spline spindle, the hydraulic motor driving the first mounting seat to move axially along the spline spindle, and the movement of the spline spindle drives the grinding head to move closer to or away from the workpiece; The tension pressure sensor is used to monitor the pressure of the grinding head on the workpiece, and the tension pressure sensor is located between the first mounting seat and the spline spindle.

2. The force-controlled grinding device according to claim 1, characterized in that: The part of the spline main shaft extending out of the housing is sealed with a rubber ring to isolate dust.

3. The force-controlled grinding device according to claim 1, characterized in that: The spline spindle is detachably connected to the grinding head.

4. The force-controlled grinding device according to claim 1, characterized in that: A dust cover is further provided between the bearing seat and the first mounting seat, and the dust cover is sleeved on the outside of the spline main shaft.

5. The force-controlled grinding device according to claim 1, characterized in that: An angular contact ball bearing is provided between the first mounting seat and the spline main shaft.

6. A control method for a force-controlled grinding device, based on the grinding device according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Obtain the set value of the grinding force; S2. The tension and pressure sensor detects in real time the current grinding force, wherein the current grinding force is the pressure exerted by the grinding head on the workpiece, which is obtained by the tension and pressure sensor detecting the tension and pressure exerted by the spline spindle on the workpiece; S3. Comparing the current grinding force with a set value; when the current grinding force is greater than the set value, the hydraulic motor reduces the movement stroke of the output shaft to ensure constant force output of the grinding head; when the current grinding force is less than the set value, the hydraulic motor increases the movement stroke of the output shaft to ensure constant force output of the grinding head; The hydraulic motor has a built-in displacement sensor to detect and correct the displacement of the output shaft of the hydraulic motor in real time.

7. A polishing robot, characterized in that: It comprises a multi-axis manipulator, on which the force-controlled grinding device according to any one of claims 1 to 5 is installed.

8. A control method for a polishing robot, based on the polishing robot according to claim 7, characterized in that: The control method comprises the following steps: S1. Obtain the set value of the grinding force; S2. The tension and pressure sensor detects in real time the current grinding force, wherein the current grinding force is the pressure exerted by the grinding head on the workpiece, which is obtained by the tension and pressure sensor detecting the tension and pressure exerted by the spline spindle on the workpiece; S3, compare the current grinding force with the set value; When the current grinding force is greater than the set value, and the difference between the current grinding force and the set value is greater than a preset threshold, the multi-axis manipulator drives the power-controlled grinding device to move away from the workpiece to reduce the grinding force; When the current grinding force is greater than a set value, and the difference between the current grinding force and the set value is less than a preset threshold, the hydraulic motor reduces the movement stroke of the output shaft to ensure a constant force output of the grinding head; When the current grinding force is less than a set value, and the difference between the set value and the current grinding force is greater than a preset threshold, the multi-axis manipulator drives the power-controlled grinding device to move toward the workpiece to increase the grinding force; When the current grinding force is less than the set value, and the difference between the set value and the current grinding force is less than a preset threshold, the hydraulic motor increases the movement stroke of the output shaft to ensure constant force output of the grinding head.

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