A lightweight flexible grinding device suitable for curved surface grinding

Abstract

The present invention relates to a lightweight flexible grinding device adapted to curved surface grinding, comprising a robot flange connecting plate, a force sensor, a force sensor connecting plate, a first pressing plate, a second pressing plate, a rubber plate, a grinding head mounting plate, a grinding head, a reflective plate, and a laser displacement sensor. The force sensor is fixedly connected to the end of the robot through the robot flange connecting plate, and the other end of the force sensor is connected to the rubber plate through the force sensor connecting plate and the first pressing plate. The force sensor connecting plate and the first pressing plate are connected to the middle part of the rubber plate, and the grinding head mounting plate and the second pressing plate are connected to the peripheral side of the rubber plate. In the curved surface grinding process, the rubber plate acts as a buffer and damping component, which can effectively adapt to the grinding and following requirements of different curved surfaces, and at the same time can improve the real-time control characteristics of the force-controlled grinding system with a force sensor and a controller, solving the problems of the current grinding device having poor adaptability to curved surfaces, low grinding force control accuracy, and large grinding head mass.

Description

Technical Field

[0001] The invention relates to the application field of industrial robots, and in particular to a lightweight flexible grinding device suitable for curved surface grinding. Background Art

[0002] In the industrial production process, grinding is a very common process. At present, most grinding processes are completed manually. Due to the harsh environment of the grinding site and the time-consuming and labor-intensive grinding process, as labor costs rise, the grinding operations on industrial sites are also facing an urgent need to replace people with machines.

[0003] For automated grinding, especially robot-based automated grinding systems, the grinding force is required to be constant during the grinding process, and the grinding process is highly adaptable to the workpiece surface, that is, the grinding head is flexible in all directions of the workpiece surface during the grinding process. On the one hand, the grinding head itself is required to have greater rigidity in the Fx, Fy, and Mz directions, and on the other hand, it is required to have good flexibility in the Mx, My, and Fz directions in order to improve the real-time performance and control characteristics of the robot control system during the surface grinding process. At the same time, with the increase of load, the price, quality, and maintenance cost of the robot all rise sharply. Therefore, the lightweight of the robot end grinding device helps to adopt robots with smaller loads and thus reduce corporate costs.

[0004] Patent number CN207171796U (a radial constant force floating device) proposes a grinding device that uses pneumatic means to achieve radial constant force and can absorb vibrations. However, the device has a complex structure, heavy weight, high manufacturing cost, and is inconvenient to use and maintain. Summary of the invention

[0005] In view of the above shortcomings, the present invention designs a lightweight flexible grinding device suitable for curved surface grinding, which solves the disadvantages of the current grinding device that it has poor adaptability to curved surfaces, low grinding force control accuracy, and large grinding head mass.

[0006] In order to achieve the above-mentioned purpose, the present invention includes a robot flange connecting plate, a force sensor, a force sensor connecting plate, a first pressure plate, a second pressure plate, a rubber plate, a grinding head mounting plate, a grinding head, a reflective plate, and a laser displacement sensor; wherein the robot flange connecting plate is connected to the end of the robot, one end of the force sensor is connected to the robot flange connecting plate, the other end of the force sensor is connected to the force sensor connecting plate, the force sensor connecting plate is connected to the middle part of the rubber plate through the first pressure plate, the grinding head mounting plate is connected to the peripheral side of the rubber plate through the second pressure plate, the grinding head is connected to the grinding head mounting plate, the laser displacement sensor is connected to the force sensor connecting plate, and the reflective plate is connected to the grinding head mounting plate.

[0007] The feature of the invention is that the force sensor is a six-dimensional force sensor.

[0008] The characteristics are as follows: the rubber plate is round, the material is preferably silicone rubber, and the Shore hardness is preferably 40 to 60 degrees.

[0009] The invention is characterized in that the force sensor connecting plate and the first pressing plate are connected to the middle part of the rubber plate, the grinding head mounting plate and the second pressing plate are connected to the peripheral side of the rubber plate, and the radial spacing between the connecting parts of the two is 3mm-8mm.

[0010] Its characteristics are as follows: For industrial occasions with relatively high requirements on grinding force and grinding head posture, the angle change between the grinding head and the six-axis force sensor is accurately measured by a laser displacement sensor, and at the same time, combined with the force feedback information of the force sensor, it is ensured that the axis of the six-axis force sensor is precisely coaxial with the axis of the grinding head, thereby achieving precise control of the grinding force and grinding posture.

[0011] Its characteristics are as follows: for cost-sensitive industrial occasions where the requirements for grinding force control accuracy are not high, the angle change between the grinding head and the six-axis force sensor is calculated only through the real-time force and torque data of the force sensor, so as to make corresponding posture adjustments to ensure that the axis of the six-axis force sensor is basically coaxial with the axis of the grinding head, thereby ensuring constant control of the grinding force during the grinding process.

[0012] The present invention has the following advantages and outstanding effects:

[0013] 1. The present invention realizes a lightweight grinding head structure suitable for curved surface grinding. During the curved surface grinding process, the rubber plate serves as a buffer and damping component. At the same time, it has greater rigidity in the Fx, Fy, and Mz directions. On the other hand, it has good flexibility in the Mx, My, and Fz directions, which can effectively adapt to the grinding and following requirements of different curved surfaces. At the same time, the real-time control characteristics of the force-controlled grinding system with force sensors and controllers can be improved.

[0014] 2. During the grinding process, the present invention can use the laser displacement sensor to accurately feedback the angle change of the grinding head and the six-axis force sensor, thereby accurately controlling the coaxiality of the grinding head and the force sensor, thereby ensuring constant grinding force during the grinding process; at the same time, for cost-sensitive industrial occasions with low grinding accuracy requirements, there is no need for a laser displacement sensor. Only the real-time force and torque data of the force sensor can be used to calculate the angle change between the grinding head and the six-axis force sensor, thereby performing corresponding posture adjustments to ensure that the axis of the six-axis force sensor is basically coaxial with the axis of the grinding head, thereby ensuring constant control of the grinding force during the grinding process.

[0015] 3. In addition, the grinding device has a simple structure, light weight, and is easy to use and maintain, which greatly reduces the cost of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram (cross-sectional view) of a lightweight flexible grinding device suitable for curved surface grinding.

[0017] Figure 2 It is an axonometric view and coordinate direction schematic diagram of a lightweight flexible grinding device suitable for curved surface grinding.

[0018] Figure 3 It is a structural schematic diagram (cross-sectional view) of a lightweight flexible grinding device without a laser displacement sensor.

[0019] Figure 4 This is the schematic diagram for determining the angle change between the grinding head and the force sensor using a laser displacement sensor. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings:

[0021] right Figure 1 Each part is described as follows:

[0022] 1. Robot flange connection plate 2. Force sensor 3. Force sensor connection plate 4. First pressure plate

[0023] 5. Second pressing plate 6. Rubber plate 7. Grinding head mounting plate 8. Grinding head 9. Reflection plate 10. Laser displacement sensor 11. Robot end

[0024] like Figure 1 As shown, a lightweight flexible grinding device adapted to curved surface grinding includes a robot flange connection plate 1, a force sensor 2, a force sensor connection plate 3, a first pressure plate 4, a second pressure plate 5, a rubber plate 6, a grinding head mounting plate 7, and a grinding head 8. The force sensor 2 is fixedly connected to the robot end 9 through the robot flange connection plate 1, and the other end of the force sensor 2 is connected to the rubber plate 6 through the force sensor connection plate 3 and the first pressure plate 4; the grinding head 8 is connected to the rubber plate 6 through the grinding head mounting plate 7 and the second pressure plate 4.

[0025] Furthermore, the force sensor 2 is a six-dimensional force sensor, that is, it has the ability to measure in the directions of Fx, Fy, Fz, Mx, My, and Mz, wherein the coordinates of the system are defined as follows: Figure 2 shown.

[0026] The rubber sheet 6 is round and preferably made of silicone rubber, which has good mechanical properties, weather resistance and aging resistance. The hardness of the rubber sheet 6 is preferably 40 to 60 degrees and the thickness is 5 mm to 12 mm. In this example, the hardness is preferably 45 degrees and the thickness is 5 mm.

[0027] The main parts except the rubber plate 6 are made of aluminum alloy, which is light in weight and high in strength.

[0028] Furthermore, the force sensor connecting plate 3 and the first pressing plate 4 are connected to the middle part of the rubber plate 6, and the grinding head mounting plate 7 and the second pressing plate 5 are connected to the circumference of the rubber plate 6 by bolts, and the radial spacing between the connecting parts is 3mm-8mm. In this way, the unpressed part of the rubber plate 6 is annular, so that the device has good flexibility in the Mx, My, and Fz directions, and has relatively large rigidity in the Fx, Fy, and Mz directions.

[0029] For cost-sensitive industrial applications where the requirements for grinding precision are not stringent, laser displacement sensors are not required. The angle change between the grinding head and the six-axis force sensor can be calculated through the real-time force and torque data of the six-axis force sensor, so as to make corresponding posture adjustments to ensure that the axis of the six-axis force sensor is basically coaxial with the axis of the grinding head, thereby ensuring the control of the grinding force and grinding posture during the grinding process. The structural composition of the embodiment is as follows: Figure 3 shown.

[0030] For industrial occasions with relatively high requirements on grinding force and grinding head posture, the laser displacement sensor can be used to accurately measure the angle change between the grinding head and the six-dimensional force sensor. At the same time, combined with the force feedback information of the force sensor, precise control of grinding force and grinding posture can be achieved.

[0031] The specific plan is as follows Figure 4 As shown, three laser displacement sensors 10 (numbered f1, f2, and f3 respectively) are installed on the force sensor connecting plate 3, and a reflector plate 9 is correspondingly installed on the grinding head mounting plate 7. The laser beam emitted by the laser displacement sensor 10 hits the reflector plate 9 and is reflected and received, so that the distance from the laser displacement sensor 10 to the reflector plate 9 can be obtained. In the embodiment, each reflector plate 9 is defined as a plane P in the same plane and is parallel to the connection plane of the grinding head mounting plate 7. The reference position of the laser displacement sensor 9 is in the same plane, defined as a plane Q, and is parallel to the connection plane of the force sensor connecting plate 3 and the force sensor 2. In this way, the plane formed by the laser displacement sensors 9 is parallel to the connection plane of the force sensor 2, and the plane formed by the reflector plate 8 is parallel to the connection surface of the grinding head. During the grinding process, due to the presence of the rubber buffer structure, an angle will appear between the two planes P and Q. At the same time, the angle change between the grinding head and the six-dimensional force sensor can be calculated by an algorithm, and the specific algorithm is as follows:

[0032] In the coordinate system based on the force sensor 2, the normal of plane Q is fixed. Three non-collinear points in space uniquely determine a plane, and the normal of plane P can be obtained based on the above principle. Laser displacement sensor 9 is used to detect the distance change between laser displacement sensor 9 and the corresponding reflector 8. The laser transmission points of laser displacement sensor 9 on reflector 8 are A (x1, y1, z1), B (x2, y2, z2), and C (x3, y3, z3). The laser displacement sensor 9 can detect the coordinates of three points A (x1, y1, z1), B (x2, y2, z2), and C (x3, y3, z3). According to the coordinates of points A, B, and C, two non-collinear vectors T1 and T2 on plane P can be obtained:

[0033]

[0034] Then the normal vector of plane P is for:

[0035]

[0036] After obtaining the normal vector of plane P, the angle between the two planes P and Q can be calculated using the following formula.

[0037]

[0038] The obtained angle change between the grinding head and the six-dimensional force sensor is fed back to the controller, and combined with the force feedback information of the force sensor, precise posture and force control can be achieved.

[0039] The present invention has the following advantages and outstanding effects:

[0040] 1. The present invention realizes a lightweight grinding head structure suitable for curved surface grinding. During the curved surface grinding process, the rubber plate serves as a buffer and damping component. At the same time, it has greater rigidity in the Fx, Fy, and Mz directions. On the other hand, it has good flexibility in the Mx, My, and Fz directions, which can effectively adapt to the grinding and following requirements of different curved surfaces. At the same time, the real-time control characteristics of the force-controlled grinding system with force sensors and controllers can be improved.

[0041] 2. During the grinding process, the present invention can use the laser displacement sensor to accurately feedback the angle change of the grinding head and the six-axis force sensor, thereby accurately controlling the coaxiality of the grinding head and the force sensor, thereby ensuring constant grinding force during the grinding process; at the same time, for cost-sensitive industrial occasions with low grinding accuracy requirements, there is no need for a laser displacement sensor. Only the real-time force and torque data of the force sensor can be used to calculate the angle change between the grinding head and the six-axis force sensor, thereby performing corresponding posture adjustments to ensure that the axis of the six-axis force sensor is basically coaxial with the axis of the grinding head, thereby ensuring constant control of the grinding force during the grinding process.

[0042] 3. In addition, the grinding device has a simple structure, light weight, and is easy to use and maintain, which greatly reduces the cost of the enterprise.

Claims

1. A lightweight flexible grinding device suitable for curved surface grinding, It is characterized in that It includes a robot flange connecting plate, a force sensor, a force sensor connecting plate, a first pressing plate, a second pressing plate, a rubber plate, a grinding head mounting plate, a grinding head, a reflecting plate, and a laser displacement sensor; the robot flange connecting plate is connected to the end of the robot, one end of the force sensor is connected to the robot flange connecting plate, the other end of the force sensor is connected to the force sensor connecting plate, the force sensor connecting plate is connected to the middle of the rubber plate through the first pressing plate, the grinding head mounting plate is connected to the peripheral side of the rubber plate through the second pressing plate, the grinding head is connected to the grinding head mounting plate, the laser displacement sensor is connected to the force sensor connecting plate, and the reflecting plate is connected to the grinding head mounting plate; The laser displacement sensors and reflective plates are arranged in pairs, and the number of the laser displacement sensors and their corresponding reflective plates are 3 or 4; The force sensor is a six-dimensional force sensor; The rubber sheet is round and made of silicone rubber with a Shore hardness of 40 to 60 and a thickness of 8mm to 15mm. The force sensor connecting plate and the first pressing plate are connected to the middle part of the rubber plate, the grinding head mounting plate and the second pressing plate are connected to the peripheral side of the rubber plate, and the radial spacing between the connecting parts of the two is 3mm-8mm.

2. A lightweight flexible grinding device adapted for curved surface grinding according to claim 1, It is characterized in that in, For industrial occasions with relatively high requirements on grinding force and grinding head posture, the laser displacement sensor is used to accurately measure the angle change between the grinding head and the six-axis force sensor. At the same time, combined with the force feedback information of the force sensor, it is ensured that the axis of the six-axis force sensor is precisely coaxial with the axis of the grinding head, thereby achieving precise control of grinding force and grinding posture.

3. A lightweight flexible grinding device adapted for curved surface grinding according to claim 1, It is characterized in that in, For cost-sensitive industrial occasions where the requirements for grinding force control accuracy are not high, the angle change between the grinding head and the six-axis force sensor is calculated only through the real-time force and torque data of the force sensor, so as to make corresponding posture adjustments to ensure that the axis of the six-axis force sensor is basically coaxial with the axis of the grinding head, thereby ensuring the control of the grinding force and grinding posture during the grinding process.

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