Hole site alignment and depth control machining device and method for weak rigidity component

Abstract

The invention relates to a weak rigidity component hole position alignment and depth control machining device and method.Three laser distance measuring sensors are evenly distributed around a spindle at the tail end of a hole making robot, during hole making, a mechanical arm drives the tail end of the hole making robot to move to the position above a hole position, and the tail end of the hole making robot conducts posture adjustment and hole making direction feeding; light emitted by the laser distance measuring sensor falls on the periphery of the hole site, and before hole making machining, the distance value measured by the laser distance measuring sensor is used for calculating the normal vector of the to-be-machined hole site and feeding back the normal vector to the hole making robot for tail end posture adjustment; in the dimple process, the distance value measured by the laser distance measuring sensor is used for calculating the workpiece surface deformation amount in real time and feeding back the workpiece surface deformation amount to the hole making robot for continuous feeding depth compensation, and hole making and dimple work is completed.

Description

Technical Field

[0001] The present invention relates to the technical field of robot drilling and countersinking, and more specifically, to a device and method for hole alignment and depth control of weakly rigid components, which is aimed at the operation scenario of hole countersinking of weakly rigid structures. Background Art

[0002] Weak rigid components have the characteristics of thin walls, weak rigidity, and easy local deformation during processing. They are widely used in the aerospace field. How to accurately make holes and dimples on the surface of weak rigid components is a technical problem that needs to be overcome urgently. Taking the typical weak rigid component hole countersinking of the surface skin of drones as an example, the connection and fixation of the drone surface skin and the internal structure requires a large number of hole countersinking. Since the drone fuselage skin is mostly molded as a whole, the precision is low, which easily leads to differences between the actual product and the theoretical model. Processing according to the theoretical model may cause problems such as incorrect hole normal. In addition, most drone fuselages are more than two meters long, and the skin is prone to deformation when making holes on the surface, and the deformation amount of different parts is different, resulting in inaccurate countersink depth. The hole normal and countersink depth of the drone surface skin affect the connection strength and fatigue life of the drone, and have an important impact on the performance of the drone. Therefore, how to accurately make holes and dimples is a very important part of the drone production process.

[0003] There have been some studies on the countersinking of weak rigid structures. The detection and correction of the hole normal are mainly divided into contact and non-contact types according to whether they touch the product. According to the different types of detection sensors, the contact detection method is mainly divided into six-dimensional force sensor-based and displacement sensor-based; the non-contact detection method is mainly divided into eddy current sensor-based and distance sensor-based. Li Pengcheng et al. designed a contact normal alignment pressure angle module and improved the contact normal alignment and posture adjustment algorithm to realize the hole countersinking of laminated plates. Similarly, Zhang Jin et al. used industrial robots as carriers to design a normal alignment mechanism based on the pressure foot clamping condition, which improved the quality of aircraft hole making. However, these require high design capabilities of personnel, and the terminal hole making device is relatively large and complex, which cannot be applied to some small hole making equipment. Duan Shukai used a cross-shaped laser as a light source to shoot on the skin, and used a monocular shooting method to process the image information of two curves on the skin to obtain the skin normal vector, but the surface of some products is prone to reflection, which affects the extraction of the cross curve. Ren Ruimin and his colleagues established a coordinate system based on a laser ranging sensor and the light spot on the surface to be measured, calculated the angle between the tool axis vector and the normal of the surface to be measured, and achieved surface normal alignment. However, they did not pay attention to problems such as workpiece deformation in the subsequent hole countersinking process. Summary of the invention

[0004] The technical problem solved by the present invention is: in the face of a large number of demands for hole countersinking of weak rigid components, it is proposed to integrate a laser ranging sensor on the hole making robot hole making equipment for normal alignment and real-time compensation of workpiece deformation during hole countersinking, aiming to solve the problem of difficult control of countersinking depth and poor precision caused by difficult normal alignment and unpredictable workpiece deformation during hole countersinking, so as to achieve fast and accurate hole countersinking.

[0005] The solution to the technical problem of the present invention is: a weak rigid component hole position alignment and depth control processing device, the processing device includes a hole making robot and three laser distance measuring sensors;

[0006] Three laser ranging sensors are evenly distributed around the end spindle of the hole-making robot. When making holes, the robotic arm drives the end of the hole-making robot to move above the hole position, and the end of the hole-making robot adjusts its posture and feeds in the hole-making direction; the laser ranging sensor emits light that falls around the hole position. Before the hole-making process, the distance value measured by the laser ranging sensor is used to calculate the normal vector of the hole to be processed, and is fed back to the hole-making robot for end posture adjustment; during the countersinking process, the distance value measured by the laser ranging sensor is used to calculate the surface deformation of the workpiece in real time, and is fed back to the hole-making robot for continuous feed depth compensation to complete the hole-making 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] Among them, P 1 , P 2 , P 3 The coordinates of the three light spots P1, P2, and P3 formed by the light emitted by the three laser distance measuring sensors and falling on the periphery of the hole to be processed in the coordinate system of the hole-making robot;

[0010] Cross(·) is a cross product operation, and norm(·) is a modulo operation.

[0011] Preferably, the deformation amount Δd is:

[0012] Δd=Z 0 '-Z 0

[0013] Among them, Z 0 Z is the Z value of the hole surface when the tool tip of the hole-making robot does not touch the hole surface of the workpiece; 0 ' is the Z value of the hole surface after the tool tip at the end of the robot moves forward along the feed direction, causing the workpiece to deform.

[0014] Based on the above device, the present invention also proposes a method for aligning the hole position of a weak rigid component, which comprises the following steps:

[0015] The end of the hole-making robot moves to the top of the hole to be processed, so that the light of the laser ranging sensor falls on the periphery of the hole to be processed;

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

[0017] The hole-making robot adjusts the end posture according to the normal vector of the hole to be processed, so that the tool 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] Among them, P 1 , P 2 , P 3 The coordinates of the three light spots P1, P2, and P3 formed by the light emitted by the three laser distance measuring sensors and falling on the periphery of the hole to be processed in the coordinate system of the hole-making robot;

[0021] Cross() is a cross product operation, and norm() is a modulo operation.

[0022] Preferably, the coordinates of the three light spots P1, P2, and P3 formed by the light emitted by the three laser distance measuring sensors and falling on the periphery of the hole to be processed in the coordinate system of the hole-making robot are:

[0023] P 1 =B 1 +L 1 l 1

[0024] P 2 =B 2 +L 2 l 2

[0025] P 3 =B 3 +L 3 l 3

[0026] Among them, B 1 , B 2 , B 3 are the coordinates of the light outlets of the three laser ranging sensors in the robot coordinate system, l 1 , l 2 , l 3 are the direction vectors of the three laser ranging sensor lights in the robot coordinate system, L 1 , L 2 , L 3It is the length of the light emitted by the three laser ranging sensors from the light outlet to the light spot.

[0027] Based on the above device, the present invention also provides a method for processing a hole countersink of a weak rigid component, the method comprising the following steps:

[0028] The end of the hole-making robot feeds in the direction of hole-making depth. At the same time, according to the readings of three laser distance measuring sensors, the Z value of the workpiece hole surface in the robot coordinate system is calculated in real time. When the tool tip descends but has not yet touched the workpiece surface, the Z value Z of the hole surface before the tool tip of the hole-making robot touches the workpiece hole surface is recorded. 0 ;

[0029] When the tool tip drops to the surface of the workpiece and continues to drop to perform drilling, the workpiece surface deforms and the Z value changes. The coordinate value of the end of the hole-making robot is recorded when the Z value just changes, which is used as the starting point for calculating the forward distance Δz.

[0030] The tool tip continues to descend to drill. During this process, the tool tip advance distance Δz is calculated 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, the Z value Z of the hole surface is calculated in real time based on the readings of the three laser ranging sensors after the tool tip at the end of the robot moves forward in the feed direction and causes the workpiece to deform. 0 ', and with the recorded Z 0 The real-time deformation Δd is obtained by subtraction, and the actual drilling depth h is calculated in real time according to the advance distance and the deformation;

[0031] The tool tip continues to descend to drill, and the actual drilling depth is compared with the theoretical drilling depth. If the required theoretical drilling depth is not reached, the tool tip is controlled to continue to descend 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=Z 0 '-Z 0

[0036] Among them, Z 0 Z is the Z value of the hole surface when the tool tip of the hole-making robot does not touch the hole surface of the workpiece; 0 ' is the Z value of the hole surface after the tool tip at the end of the robot moves forward along the feed direction, causing the workpiece to deform.

[0037] The beneficial effects of the present invention compared with the prior art are:

[0038] The present invention is based on a hole-making robot equipped with a countersink for weakly rigid components, and proposes integrating three laser ranging sensors at the end of the hole-making robot for normal alignment of the hole position. The data of the laser ranging sensors are used in real time during the hole-making process to compensate for the surface deformation of the workpiece, thereby achieving precise hole-making and countersinking of weakly rigid components. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of this application. The illustrative examples of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0040] Figure 1 Schematic diagram of the end of the hole-making robot according to an embodiment of the present invention, wherein 1 is a laser distance sensor, 2 is a connecting frame, 3 is light, 4 is a main axis, 5 is a tool, and 6 is a weakly rigid workpiece surface;

[0041] Figure 2 This is a simplified structural diagram of the laser distance measuring sensor according to an embodiment of the present invention, wherein light is projected onto the surface of a workpiece;

[0042] Figure 3 This is a diagram for analyzing the principle of workpiece surface deformation during the robot hole countersinking process according to an embodiment of the present invention;

[0043] Figure 4 The present invention is a robot hole countersinking process according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with the embodiments.

[0045] The schematic diagram of the entire hole-making robot equipment terminal is as follows Figure 1 As shown, three laser distance measuring sensors 1 are evenly distributed around the end spindle 4 of the hole-making robot through the connecting frame 2. When making holes, the mechanical arm drives the end of the hole-making robot to move above the hole position, and the end of the hole-making robot drives the tool 5 to adjust the posture and feed in the hole-making direction; the laser distance measuring sensor emits light 3 that falls around the hole position. Before the hole-making process, the distance value measured by the laser distance measuring sensor is used to calculate the normal vector of the hole position to be processed on the surface 6 of the weak rigid workpiece, and is fed back to the hole-making robot for end posture adjustment; during the countersinking process, the distance value measured by the laser distance measuring sensor is used to calculate the deformation of the workpiece surface in real time, and is fed back to the hole-making robot to continuously compensate for the feeding depth to complete the hole-making countersinking work. The specific principle is as follows.

[0046] (1) Hole normal alignment

[0047] Due to the processing and installation errors of laser ranging sensors, the installation position of the sensors has been calibrated before use. Now, assuming that the three laser ranging sensors are installed in the theoretical position, the three sensor light outlets B can be determined according to the hole-making robot model and robot kinematics. 1 , B 2 , B 3 The coordinates in the robot coordinate system and the direction vectors l of the three laser ranging sensor lights in the robot coordinate system 1 , l 2 , l 3 , the length L of the light emitted by the three laser distance sensors from the light outlet to the light spot 1 , L 2 , L 3 It can be obtained by measuring the value of the sensor, such as Figure 2 As a preferred solution, the light-emitting points of the three laser distance measuring sensors can be installed on the same plane perpendicular to the main axis and located on a circle with the center of the intersection of the main axis and the plane, and the arc segment between two adjacent light-emitting points is 120°.

[0048] Then the three light spots P that fall around the workpiece hole 1 , P 2 , P 3 The coordinates in the robot coordinate system can be obtained according to the following formula:

[0049] P 1 =B 1 +L 1 l 1

[0050] P 2 =B 2 +L 2 l 2

[0051] P 3 =B 3 +L 3 l 3

[0052] According to 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 obtained as follows:

[0053]

[0054] Among them, P 1 , P 2 , P 3 The coordinates of the three light spots P1, P2, and P3 formed by the light emitted by the three laser distance measuring sensors and falling on the periphery of the hole to be processed in the coordinate system of the hole-making robot;

[0055] Cross(·) is a cross product operation, and norm(·) is a modulo operation.

[0056] (2) Countersink depth control

[0057] Assuming that the robot’s hole-making feed direction is the Z direction, since the laser ranging sensor’s landing point range around the workpiece hole is very small, the light spot P 1 , P 2 , P 3 The coordinates are approximately used to obtain the Z value of the current hole surface:

[0058]

[0059] Among them ZP 1 , ZP 2 , ZP 3 Point P 1 , P 2 , P 3 The Z value of the coordinate.

[0060] Assume that after the tool tip of the robot contacts the hole surface of the weakly rigid workpiece, the forward distance is Δz. During this process, the workpiece deforms by Δd, and the actual drilling depth is h. Figure 3 As shown, then:

[0061] h=Δz-Δd

[0062] Among them, Δz can be directly read from the robot coordinate value.

[0063] For the deformation Δd, assuming that the end tool tip of the hole-making robot does not touch the hole surface of the workpiece, the Z value of the hole surface is Z 0 ; After the tool tip at the end of the robot moves forward in the feed direction, causing the workpiece to deform, the Z value of the hole surface is Z 0 ', then the deformation Δd is:

[0064] Δd=Z 0 '-Z 0

[0065] And Z 0 ' and Z 0 It can be calculated in real time by the laser ranging sensor value, so the actual drilling depth h can be obtained in real time.

[0066] During the entire robot hole countersinking process, the laser ranging sensor value is read at all times to calculate the surface deformation Δd of the workpiece at this time. 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 countersinking depth reaches the theoretical value and the processing is completed.

[0067] (3) Hole alignment method

[0068] Based on the above principle, the method of using a hole-making robot to align the hole position of a weakly rigid workpiece is as follows:

[0069] The end of the hole-making robot moves to the top of the hole to be processed, so that the light of the laser ranging sensor falls on the periphery of the hole to be processed;

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

[0071] The hole-making robot adjusts the end posture according to the normal vector of the hole to be processed, so that the tool axis is perpendicular to the hole to be processed.

[0072] (4) Hole countersinking process

[0073] According to the above principle, the process of using a hole-making robot to make holes and countersinks on weak rigid workpieces is as follows: Figure 4 As shown:

[0074] The end of the hole-making robot feeds in the direction of hole-making depth. At the same time, according to the readings of three laser distance measuring sensors, the Z value of the workpiece hole surface in the robot coordinate system is calculated in real time. When the tool tip descends but has not yet touched the workpiece surface, the Z value Z of the hole surface before the tool tip of the hole-making robot touches the workpiece hole surface is recorded. 0 ;

[0075] When the tool tip drops to the surface of the workpiece and continues to drop to perform drilling, the workpiece surface deforms and the Z value changes. The coordinate value of the end of the hole-making robot is recorded when the Z value just changes, which is used as the starting point for calculating the forward distance Δz.

[0076] The tool tip continues to descend to drill. During this process, the tool tip advance distance Δz is calculated 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, the Z value Z of the hole surface after the tool tip at the end of the robot advances Δz along the feed direction is calculated in real time based on the readings of the three laser ranging sensors. 0 ', and with the recorded Z 0 The real-time deformation Δd is obtained by subtraction, and the actual drilling depth h is calculated in real time according to the advance distance and the deformation;

[0077] The actual drilling depth is:

[0078] h=Δz-Δd.

[0079] The tool tip continues to descend to drill, and the actual drilling depth is compared with the theoretical drilling depth. If the required theoretical drilling depth is not reached, the tool tip is controlled to continue to descend until the actual drilling depth reaches the theoretical drilling depth.

[0080] Compared with the prior art, the present invention integrates a laser ranging sensor at the end of the hole countersinking robot equipment, which not only realizes the alignment of the hole position normal, but also uses the sensor value to complete the real-time compensation of the workpiece deformation during the countersinking process, solves the problem of accurate countersinking when the deformation of the weak rigid component during the hole countersinking process is unpredictable, and ensures the processing quality.

[0081] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A device for hole alignment and depth control of weak rigid components, characterized in that Includes a hole-making robot and three laser range sensors; Three laser ranging sensors are evenly distributed around the end spindle of the hole-making robot. When making holes, the robotic arm drives the end of the hole-making robot to move above the hole position, and the end of the hole-making robot adjusts its posture and feeds in the hole-making direction; the laser ranging sensor emits light that falls around the hole position. Before the hole-making process, the distance value measured by the laser ranging sensor is used to calculate the normal vector of the hole to be processed, and is fed back to the hole-making robot for end posture adjustment; during the countersinking process, the distance value measured by the laser ranging sensor is used to calculate the surface deformation of the workpiece in real time, and is fed back to the hole-making robot for continuous feed depth compensation to complete the hole-making countersinking work.

2. According to claim 1, a weak rigid component hole alignment and depth control processing device is characterized in that: The normal vector of the hole to be processed in the coordinate system of the hole-making robot is: Among them, P1, P2, and P3 are the coordinates of the three light spots P1, P2, and P3 formed by the light emitted by the three laser ranging sensors falling on the periphery of the hole to be processed in the coordinate system of the hole-making robot; Cross(·) is a cross product operation, and norm(·) is a modulo operation.

3. According to claim 1, a weak rigid component hole alignment and depth control processing device is characterized in that: The deformation Δd is: Δd=Z0'-Z0 Among them, Z0 is the Z value of the hole surface when the tool tip of the end hole-making robot does not touch the hole surface of the workpiece; Z0' is the Z value of the hole surface after the tool tip of the end hole-making robot moves forward along the feed direction, causing the workpiece to deform.

4. A method for aligning the hole position of a weak rigid component based on the device described in claim 1, characterized in that The steps include: The end of the hole-making robot moves to the top of the hole to be processed, so that the light of the laser ranging sensor falls on the periphery of the hole to be processed; Calculate the normal vector of the hole to be processed in the coordinate system of the hole-making robot; The hole-making robot adjusts the end posture according to the normal vector of the hole to be processed, so that the tool axis is perpendicular to the hole to be processed.

5. A method for aligning the hole position of a weakly rigid component according to the device of claim 4, characterized in that The normal vector of the hole to be processed in the coordinate system of the hole-making robot is: Among them, P1, P2, and P3 are the coordinates of the three light spots P1, P2, and P3 formed by the light emitted by the three laser ranging sensors falling on the periphery of the hole to be processed in the coordinate system of the hole-making robot; Cross(·) is a cross product operation, and norm(·) is a modulo operation.

6. A method for aligning the hole position of a weakly rigid component according to the device of claim 4, characterized in that The three laser ranging sensors emit light and fall on the periphery of the hole to be processed to form three light spots P1, P2, and P3. The coordinates of the three light spots P1, P2, and P3 in the coordinate system of the hole-making robot are: P1=B1+L1l1 P2=B2+L2l2 P3=B3+L3l3 Among them, B1, B2, and B3 are the coordinates of the light outlets of the three laser ranging sensors in the robot coordinate system, l1, l2, and l3 are the direction vectors of the light from the three laser ranging sensors in the robot coordinate system, and L1, L2, and L3 are the lengths of the light emitted by the three laser ranging sensors from the light outlet to the light spot.

7. A method for countersinking a weak rigid component according to the device of claim 4, characterized in that The steps include: The end of the hole-making robot feeds in the direction of hole-making depth, and at the same time, calculates the Z value of the workpiece hole surface in the robot coordinate system in real time based on the readings of the three laser range sensors. When the tool tip descends but has not yet touched the workpiece surface, the Z value Z0 of the hole surface is recorded before the tool tip of the hole-making robot ends touches the workpiece hole surface. When the tool tip drops to the surface of the workpiece and continues to drop to perform drilling, the workpiece surface deforms and the Z value changes. The coordinate value of the end of the hole-making robot is recorded when the Z value just changes, which is used as the starting point for calculating the forward distance Δz. The tool tip continues to descend to drill. In this process, the tool tip advance distance Δz is calculated 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, the Z value Z0' of the hole surface after the tool tip at the end of the robot moves forward in the feed direction and causes the workpiece to deform is calculated in real time based on the readings of the three laser ranging sensors. The Z value is subtracted from the recorded Z0 to obtain the real-time deformation Δd. The actual drilling depth h is calculated in real time based on the advance distance and deformation. The tool tip continues to descend to drill, and the actual drilling depth is compared with the theoretical drilling depth. If the required theoretical drilling depth is not reached, the tool tip is controlled to continue to descend until the actual drilling depth reaches the theoretical drilling depth.

8. A method for countersinking a weakly rigid component according to the device of claim 4, characterized in that: The actual drilling depth is: h=Δz-Δd.

9. A method for countersinking a weakly rigid component according to the device of claim 4, characterized in that: The deformation Δd is: Δd=Z0'-Z0 Among them, Z0 is the Z value of the hole surface when the tool tip of the end hole-making robot does not touch the hole surface of the workpiece; Z0' is the Z value of the hole surface after the tool tip of the end hole-making robot moves forward along the feed direction, causing the workpiece to deform.

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