A machining device and method for aligning and controlling the depth of holes in weakly rigid components.

Abstract

This invention relates to a machining device and method for aligning and controlling the depth of holes in weakly rigid components. Three laser rangefinders are evenly distributed around the end-effector of a hole-making robot. During hole making, the robotic arm drives the end-effector of the hole-making robot to move above the hole position. The end-effector of the hole-making robot adjusts its posture and feeds in the hole-making direction. The laser rangefinders emit light that falls around the hole position. Before hole making, the distance values ​​measured by the laser rangefinders are used to calculate the normal vector of the hole position to be processed, and this data is fed back to the hole-making robot for end-effector posture adjustment. During the countersinking process, the distance values ​​measured by the laser rangefinders are used to calculate the workpiece surface deformation in real time, and this data is fed back to the hole-making robot for continuous depth compensation, completing the hole-making and countersinking work.

Description

Technical Field

[0001] This invention relates to the field of robotic drilling and countersinking technology, and more specifically, to a processing device and method for hole positioning and depth control of weakly rigid components, for the operation scenario of hole countersinking of weakly rigid structures. Background Technology

[0002] Weakly rigid components, characterized by thin walls, low rigidity, and susceptibility to localized deformation under stress during processing, are widely used in the aerospace field. Precisely creating countersunk holes on the surface of these components is a pressing technical challenge. Taking the countersunk hole creation of a typical weakly rigid component—the surface skin of a drone—as an example, the connection and fixation between the drone's surface skin and internal structure requires numerous countersunk holes. Since drone fuselage skins are mostly molded integrally, their precision is low, easily leading to discrepancies between the actual product and the theoretical model. Processing according to the theoretical model may result in problems such as incorrect hole normal orientation. Furthermore, drone fuselages are mostly over two meters long, making them prone to deformation during surface hole creation, with varying deformation amounts in different areas, leading to inaccurate countersunk hole depths. The hole normal orientation and countersunk hole depth of the drone's surface skin significantly affect the connection strength and fatigue life of the drone, thus having a crucial impact on its performance. Therefore, precise hole creation and countersunk hole creation is a critical step in the drone manufacturing process.

[0003] For hole-making and countersinking of weakly rigid structures, some research has been conducted. Among these, the detection and correction of the hole normal can be mainly divided into contact and non-contact methods based on whether it contacts the product. Depending on the type of sensor, contact detection methods are mainly divided into those based on six-dimensional force sensors and those based on displacement sensors; non-contact detection methods are mainly divided into those based on eddy current sensors and those based on distance sensors. Li Pengcheng et al. improved the contact normal alignment and attitude adjustment algorithm by designing a contact normal alignment pressure angle module, thus realizing hole-making and countersinking of laminated plates. Similarly, Zhang Jin et al. designed a normal alignment mechanism based on pressure foot clamping conditions using an industrial robot, improving the hole-making quality of aircraft. However, these methods require high design capabilities from personnel, and the end-effector hole-making devices are relatively large and complex, making them unsuitable for some compact hole-making equipment configurations. Duan Shukai used a cross-shaped laser as a light source to shine on the skin and used monocular imaging to process the image information of two curves on the skin to obtain the skin normal vector; however, the reflective nature of some product surfaces easily affects the extraction of the cross curves. Ren Ruimin et al. established a coordinate system based on the light spot on the surface to be measured using a laser rangefinder sensor, and calculated the angle between the cutter axis vector and the normal of the surface to be measured, thus achieving surface normal alignment. However, they did not pay attention to issues such as workpiece deformation during the subsequent hole-making and countersinking process. Summary of the Invention

[0004] The technical problem solved by this invention is: facing the demand for large-scale hole drilling and countersinking of weak rigid components, it proposes to integrate a laser rangefinder sensor into the hole drilling robot equipment for real-time normal alignment and workpiece deformation compensation during the hole drilling and countersinking process. This aims to solve the problems of difficult normal alignment and unpredictable workpiece deformation during the hole drilling and countersinking process, which lead to poor control of countersinking depth and low accuracy, and achieve rapid and accurate hole drilling and countersinking.

[0005] The solution to the technical problem of the present invention is: a processing device for aligning and controlling the depth of holes in weakly rigid components, the processing device including a hole-making robot and three laser rangefinders;

[0006] Three laser rangefinders are evenly distributed around the end spindle of the hole-making robot. During hole making, the robotic arm drives the end spindle of the hole-making robot to move above the hole position. The end spindle of the hole-making robot adjusts its posture and feeds in the hole-making direction. The laser rangefinders emit light that falls around the hole position. Before hole making, the distance values ​​measured by the laser rangefinders are used to calculate the normal vector of the hole position to be processed and fed back to the hole-making robot for end-effector posture adjustment. During the countersinking process, the distance values ​​measured by the laser rangefinders are used to calculate the workpiece surface deformation in real time and fed back to the hole-making robot for continuous feed depth compensation to complete the hole-making and countersinking work.

[0007] Preferably, the normal vector of the hole to be processed in the coordinate system of the hole-making robot is:

[0008]

[0009] Wherein, P1, P2, and P3 are the coordinates of the three light points P1, P2, and P3 formed by the light rays emitted from the three laser rangefinders falling around the hole to be processed in the coordinate system of the hole-making robot.

[0010] Cross(·) performs the cross product operation, and norm(·) performs the modulo operation.

[0011] Preferably, the deformation amount Δd is:

[0012] Δd=Z0'-Z0

[0013] Wherein, Z0 is the Z value of the hole surface when the tip of the end-effector of the drilling robot does not contact the hole surface of the workpiece; Z0' is the Z value of the hole surface after the workpiece is deformed due to the tip of the end-effector moving forward along the feed direction.

[0014] Based on the above-mentioned device, the present invention also proposes a method for aligning the hole position of a weakly rigid component, the method comprising the following steps:

[0015] The end effector of the hole-making robot moves to a position above the hole to be processed, so that the laser rangefinder's light falls around the hole to be processed;

[0016] Calculate the normal vector of the hole to be machined in the coordinate system of the hole-making robot;

[0017] The hole-making robot adjusts its end-effector posture based on the normal vector of the hole to be processed, so that the cutter axis is perpendicular to the hole to be processed.

[0018] Preferably, the normal vector of the hole to be processed in the coordinate system of the hole-making robot is:

[0019]

[0020] Wherein, P1, P2, and P3 are the coordinates of the three light points P1, P2, and P3 formed by the light rays emitted from the three laser rangefinders falling around the hole to be processed in the coordinate system of the hole-making robot.

[0021] Cross() performs the cross product operation, and norm() performs the modulo operation.

[0022] Preferably, the coordinates of the three light points P1, P2, and P3 formed by the light rays emitted from the three laser rangefinders falling around the hole to be processed, in the coordinate system of the hole-making robot, are as follows:

[0023] P1=B1+L1l1

[0024] P2=B2+L2l2

[0025] P3=B3+L3l3

[0026] Where B1, B2, and B3 are the coordinates of the light output ports of the three laser rangefinders in the robot coordinate system, l1, l2, and l3 are the direction vectors of the light rays from the three laser rangefinders in the robot coordinate system, and L1, L2, and L3 are the lengths of the light rays emitted from the three laser rangefinders from the light output ports to the light spots.

[0027] Based on the above-described apparatus, the present invention also provides a method for countersinking holes in weakly rigid components, the method comprising the following steps:

[0028] The end effector of the hole-making robot feeds in the direction of hole depth. At the same time, based on the readings of three laser rangefinders, the Z value of the workpiece hole surface in the robot coordinate system is calculated in real time. During the process of the tool tip descending but not yet contacting the workpiece surface, the Z value of the hole surface Z0 is recorded before the tool tip of the end effector of the hole-making robot contacts the workpiece hole surface.

[0029] When the cutting tip descends to contact the workpiece surface and continues to descend to perform the drilling action, the workpiece surface deforms and the Z value changes. The coordinate value of the end of the drilling robot is recorded when the Z value just changes, which is used as the starting point for calculating the forward distance Δz.

[0030] The cutting edge continues to descend to drill. During this process, the robot's current coordinates are continuously compared with the recorded starting coordinates when it contacts the workpiece surface to calculate the cutting edge's forward distance Δz. At the same time, based on the readings of the three laser rangefinders, the Z value Z0' of the hole surface is calculated in real time after the workpiece is deformed due to the cutting edge's forward movement along the feed direction at the robot's end point. The difference between this value and the recorded Z0 is used to obtain the real-time deformation amount Δd. The actual drilling depth h is calculated in real time based on the forward distance and the deformation amount.

[0031] The cutting edge continues to descend to drill, while the actual drilling depth is compared with the theoretical drilling depth. If the required theoretical drilling depth is not reached, the cutting edge is controlled to continue descending until the actual drilling depth reaches the theoretical drilling depth.

[0032] Preferably, the actual drilling depth is:

[0033] h = Δz - Δd.

[0034] Preferably, the deformation amount Δd is:

[0035] Δd=Z0'-Z0

[0036] Wherein, Z0 is the Z value of the hole surface when the tip of the end-effector of the drilling robot does not contact the hole surface of the workpiece; Z0' is the Z value of the hole surface after the workpiece is deformed due to the tip of the end-effector moving forward along the feed direction.

[0037] The advantages of this invention compared to the prior art are:

[0038] This invention is based on a hole-making robot for drilling and countersinking weak rigid components. It proposes to integrate three laser rangefinders at the end of the hole-making robot for aligning the normal direction of the hole position, and to use the data from the laser rangefinders in real time during the hole-making process to compensate for the deformation of the workpiece surface, thereby achieving precise hole-making and countersinking of weak rigid components. Attached Figure Description

[0039] The accompanying drawings are provided to further illustrate the invention and form part of this application. The illustrative examples and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0040] Figure 1 This is a schematic diagram of the end effector of the hole-making robot according to an embodiment of the present invention, wherein 1 is a laser rangefinder, 2 is a connecting frame, 3 is a light beam, 4 is a main shaft, 5 is a cutting tool, and 6 is a weakly rigid workpiece surface;

[0041] Figure 2 This is a simplified diagram of the structure of the laser rangefinder sensor beam striking the workpiece surface according to an embodiment of the present invention;

[0042] Figure 3This is a diagram illustrating the principle of workpiece surface deformation during the robot-assisted hole-making and countersinking process according to an embodiment of the present invention.

[0043] Figure 4 This is a robot-assisted hole-making and countersinking process according to an embodiment of the present invention. Detailed Implementation

[0044] The present invention will be further described below with reference to the embodiments.

[0045] A schematic diagram of the end effector of the complete hole-making robot equipment is shown below. Figure 1 As shown, three laser rangefinders 1 are evenly distributed around the end-effector 4 of the hole-making robot via a connecting frame 2. During hole making, the robotic arm drives the end-effector of the hole-making robot to move above the hole position. The end-effector of the hole-making robot drives the cutting tool 5 to adjust its posture and feed in the hole-making direction. The laser beams 3 emitted by the laser rangefinders fall around the hole position. Before hole making, the distance values ​​measured by the laser rangefinders are used to calculate the normal vector of the hole position on the surface 6 of the weakly rigid workpiece, and fed back to the hole-making robot for end-effector posture adjustment. During the countersinking process, the distance values ​​measured by the laser rangefinders are used to calculate the workpiece surface deformation in real time, and fed back to the hole-making robot for continuous feed depth compensation to complete the hole-making and countersinking work. The specific principle is as follows.

[0046] (1) Hole position normal alignment

[0047] Due to manufacturing and installation errors in laser rangefinders, the sensor installation positions were calibrated before use. Assuming all three laser rangefinders are installed in their theoretical positions, the coordinates of the light outlets B1, B2, and B3 of the three sensors in the robot coordinate system, as well as the direction vectors l1, l2, and l3 of the laser rays emitted from the three sensors in the robot coordinate system, can be determined based on the hole-making robot model and robot kinematics. The lengths L1, L2, and L3 of the laser rays emitted from the three sensors from the light outlets to the light spot can be obtained from the sensor measurements. Figure 2 As shown. As a preferred embodiment, the light emission points of the three laser rangefinders can be mounted on the same plane perpendicular to the main axis, and located on a circle centered at the intersection of the main axis and the plane, with the arc between two adjacent light emission points being 120°.

[0048] The coordinates of the three light points P1, P2, and P3 falling around the workpiece hole in the robot coordinate system can be obtained using the following formula:

[0049] P1=B1+L1l1

[0050] P2=B2+L2l2

[0051] P3=B3+L3l3

[0052] Based on the coordinates of P1, P2, and P3, the normal vector of the hole to be processed in the coordinate system of the hole-making robot is calculated as follows:

[0053]

[0054] Wherein, P1, P2, and P3 are the coordinates of the three light points P1, P2, and P3 formed by the light rays emitted from the three laser rangefinders falling around the hole to be processed in the coordinate system of the hole-making robot.

[0055] Cross(·) performs the cross product operation, and norm(·) performs the modulo operation.

[0056] (2) Control of countersink depth

[0057] Assuming the robot's hole-making feed direction is the Z direction, since the laser rangefinder's landing point range around the workpiece hole is very small, the current Z value of the hole surface can be approximated by the coordinates of the light points P1, P2, and P3:

[0058]

[0059] ZP1, ZP2, and ZP3 are the Z-coordinates of points P1, P2, and P3, respectively.

[0060] Assume the robot's end effector tip travels a distance Δz after contacting the surface of a hole in a weakly rigid workpiece. During this process, the workpiece deforms by an amount Δd, and the actual drilling depth is h. Figure 3 As shown, then:

[0061] h=Δz-Δd

[0062] Δz can be directly read from the robot's coordinate values.

[0063] For the deformation amount Δd, assuming that the Z-value of the hole surface is Z0 when the end effector tip of the drilling robot does not contact the workpiece hole surface; and the Z-value of the hole surface is Z0' after the end effector tip moves forward along the feed direction causing workpiece deformation, then the deformation amount Δd is:

[0064] Δd=Z0'-Z0

[0065] Z0' and Z0 can be calculated in real time from the values ​​of the laser rangefinder, thus the actual borehole depth h can be obtained in real time.

[0066] Throughout the entire process of the robot drilling and countersinking, the laser rangefinder continuously reads the values ​​and calculates the workpiece surface deformation Δd. Then, the actual drilling depth h is compared with the theoretical value, and the difference is returned to the robot control system in real time until the final drilling and countersinking depth reaches the theoretical value, thus completing the processing.

[0067] (3) Hole positioning method

[0068] Based on the above principles, the method for aligning holes in weakly rigid workpieces using a hole-making robot is as follows:

[0069] The end effector of the hole-making robot moves to a position above the hole to be processed, so that the laser rangefinder's light falls around the hole.

[0070] Calculate the normal vector of the hole to be machined in the coordinate system of the hole-making robot;

[0071] The hole-making robot adjusts its end-effector posture based on the normal vector of the hole to be processed, so that the cutter axis is perpendicular to the hole to be processed.

[0072] (4) Hole making and countersinking process

[0073] Based on the above principles, the process of using a hole-making robot to perform hole-making and countersinking on weakly rigid workpieces is as follows: Figure 4 As shown:

[0074] The end effector of the hole-making robot feeds in the direction of hole depth. At the same time, based on the readings of three laser rangefinders, the Z value of the workpiece hole surface in the robot coordinate system is calculated in real time. During the process of the tool tip descending but not yet contacting the workpiece surface, the Z value of the hole surface Z0 is recorded before the tool tip of the end effector of the hole-making robot contacts the workpiece hole surface.

[0075] When the cutting tip descends to contact the workpiece surface and continues to descend to perform the drilling action, the workpiece surface deforms and the Z value changes. The coordinate value of the end of the drilling robot is recorded when the Z value just changes, which is used as the starting point for calculating the forward distance Δz.

[0076] The cutting edge continues to descend to drill. During this process, the robot continuously calculates the forward distance Δz of the cutting edge by subtracting the current coordinate value of the robot from the recorded starting coordinate value when it contacts the workpiece surface. At the same time, based on the readings of the three laser rangefinders, the Z value Z0' of the hole surface after the cutting edge of the robot's end point advances Δz along the feed direction is calculated in real time, and the difference between this value and the recorded Z0 is used to obtain the real-time deformation amount Δd. The actual drilling depth h is calculated in real time based on the forward distance and the deformation amount.

[0077] The actual drilling depth is:

[0078] h = Δz - Δd.

[0079] The cutting edge continues to descend to drill, while the actual drilling depth is compared with the theoretical drilling depth. If the required theoretical drilling depth is not reached, the cutting edge is controlled to continue descending until the actual drilling depth reaches the theoretical drilling depth.

[0080] This invention integrates a laser rangefinder sensor at the end of a hole-making and countersinking robot. Compared with existing technologies, this invention not only achieves the alignment of the hole position normal, but also uses sensor values ​​to complete real-time compensation for workpiece deformation during the countersinking process. This solves the problem of accurate countersinking when the deformation of weak rigid components is unpredictable, thus ensuring processing quality.

[0081] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A machining device for aligning and controlling the depth of holes in weakly rigid components, characterized in that... Includes a drilling robot and three laser rangefinders; Three laser rangefinders are evenly distributed around the end-effector of the hole-making robot. During hole making, the robotic arm moves the end-effector of the hole-making robot above the hole position, and the end-effector adjusts its posture and feeds in the hole-making direction. The laser rangefinders emit light that falls around the hole position. Before hole making, the distance values ​​measured by the laser rangefinders are used to calculate the normal vector of the hole position to be processed, and are fed back to the hole-making robot for end-effector posture adjustment. During the countersinking process, the distance values ​​measured by the laser rangefinders are used to calculate the workpiece surface deformation in real time, and are fed back to the hole-making robot for continuous feed depth compensation to complete the hole-making and countersinking work. The normal vector of the hole to be processed in the coordinate system of the hole-making robot is: in, , , The coordinates of three light points P1, P2, and P3 formed by the light rays emitted from the three laser rangefinders falling around the hole to be processed, in the coordinate system of the hole-making robot. For cross product operation, For modulo operation; The deformation Δd is: in, The Z-value of the hole surface when the tip of the end effector of the hole-making robot does not contact the hole surface of the workpiece. The Z-value of the hole surface is the result of workpiece deformation caused by the robot's end-effector tip moving along the feed direction.

2. A method for aligning the hole position of a weakly rigid component based on the device described in claim 1, characterized in that... Includes the following steps: The end effector of the hole-making robot moves to a position above the hole to be processed, so that the laser rangefinder's light falls around the hole to be processed; Calculate the normal vector of the hole to be machined in the coordinate system of the hole-making robot; The hole-making robot adjusts its end-effector posture based on the normal vector of the hole to be processed, so that the cutter axis is perpendicular to the hole to be processed.

3. A method for aligning the hole position of a weakly rigid component according to claim 2, characterized in that... The normal vector of the hole to be processed in the coordinate system of the hole-making robot is: in, , , The coordinates of three light points P1, P2, and P3 formed by the light rays emitted from the three laser rangefinders falling around the hole to be processed, in the coordinate system of the hole-making robot. For cross product operation, This is a modulo operation.

4. A method for aligning the hole position of a weakly rigid component according to claim 2, characterized in that... The coordinates of the three light points P1, P2, and P3 formed by the light rays emitted from the three laser rangefinders falling around the hole to be processed, in the coordinate system of the hole-making robot, are as follows: Where B1, B2, and B3 are the coordinates of the light output ports of the three laser rangefinders in the robot coordinate system, l1, l2, and l3 are the direction vectors of the light rays from the three laser rangefinders in the robot coordinate system, and L1, L2, and L3 are the lengths of the light rays emitted from the three laser rangefinders from the light output ports to the light spots.

5. A method for countersinking holes in a weakly rigid component using the apparatus described in claim 2, characterized in that... Includes the following steps: The end effector of the hole-making robot feeds in the direction of hole depth. At the same time, based on the readings of three laser rangefinders, the Z value of the workpiece hole surface in the robot coordinate system is calculated in real time. During the process of the tool tip descending but not yet contacting the workpiece surface, the Z value of the hole surface Z0 is recorded before the tool tip of the end effector of the hole-making robot contacts the workpiece hole surface. When the cutting tip descends to contact the workpiece surface and continues to descend to perform the drilling action, the workpiece surface deforms and the Z value changes. The coordinate value of the end of the drilling robot is recorded when the Z value just changes, which is used as the starting point for calculating the forward distance Δz. The cutting edge continues to descend for drilling. During this process, the robot's current coordinates are continuously compared to the recorded starting coordinates at the point of contact with the workpiece surface to calculate the cutting edge's forward distance Δz. Simultaneously, based on readings from three laser rangefinders, the Z-value of the hole surface is calculated in real-time after workpiece deformation caused by the cutting edge's forward movement along the feed direction at the robot's end effector. The real-time deformation Δd is obtained by subtracting it from the recorded Z0, and the actual drilling depth h is calculated in real time based on the forward distance and the deformation. The cutting edge continues to descend to drill, while the actual drilling depth is compared with the theoretical drilling depth. If the required theoretical drilling depth is not reached, the cutting edge is controlled to continue descending until the actual drilling depth reaches the theoretical drilling depth.

6. A method for countersinking holes in a weakly rigid component according to the device described in claim 5, characterized in that, The actual drilling depth is: 。 7. A method for countersinking holes in a weakly rigid component according to the device described in claim 5, characterized in that, The deformation Δd is: in, The Z-value of the hole surface when the tip of the end effector of the hole-making robot does not contact the hole surface of the workpiece. The Z-value of the hole surface is the result of workpiece deformation caused by the robot's end-effector tip moving along the feed direction.

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