Automated flexible contact hole axis detection alignment device and method

Abstract

The application provides an automatic flexible contact hole axis detection and alignment device and method, which comprises the following steps: a length gauge mounting support is connected with a base; a plurality of ear-shaped bosses are arranged on the front and back opposite surfaces of the length gauge mounting support, which are used for mounting a plurality of length gauges; a probe rod is connected with a probe rod quick connection plate through the length gauge mounting support; the probe rod quick connection plate and the probe rod connected with the probe rod quick connection plate are mounted on an upper mounting disc of a flexible compensation device; a lower mounting disc of the flexible compensation device is connected with a flexible compensation device mounting bottom plate; a flexible compensation device mounting base is connected with a floating end of an axial floating mechanism; a fixed end of the axial floating mechanism is connected with the base; a proximity switch is mounted on a proximity switch mounting seat, and the proximity switch mounting seat is connected with the base. The application is suitable for the characteristics of a small length-diameter ratio (a hole diameter is greater than a thickness) of a primary hole on a thin-walled workpiece, and is suitable for a variety of thicknesses and a variety of hole diameters of a skin.

Description

Technical Field

[0001] This invention relates to the field of automated aircraft assembly, specifically to an automated flexible contact-type hole axis detection and alignment device and method. Background Technology

[0002] The structural rigidity and fatigue strength requirements of aircraft structures necessitate highly precise automated machining equipment. Furthermore, the number of holes to be machined on aircraft skins is in the tens of thousands, and traditional machining methods would be extremely time-consuming, severely limiting the increase in aircraft production capacity. Neither existing automated equipment nor traditional manual machining can complete the initial hole countersinking process with high precision and efficiency.

[0003] This invention targets the field of automated aircraft assembly, specifically addressing the need for automated single-sided countersinking processing of large and medium-sized skins with pre-drilled holes. Aerospace assembly processes place extremely high demands on the coaxiality of the countersink and pre-drilled through holes. Existing technologies cannot simultaneously meet the requirements for high-precision, high-efficiency automated inspection and alignment of pre-drilled holes on thin-walled workpieces.

[0004] The problem this invention aims to solve in automated aircraft assembly is to automatically measure and align the positions and axes of existing through holes on sheet metal workpieces using automated machining equipment. This allows machining tools or assembly parts to align with the through hole features with high precision, resulting in high-quality automated machining.

[0005] Patent document CN109483273A (application number: 201811339924.9) discloses a rapid under-machine alignment device and method, mainly composed of a base plate, an angular positioning component, an end ruler, a dial indicator, a positioning base plate, a positioning disc, and a pressure plate. The end ruler, angular positioning component, and dial indicator are installed on the base plate. The end ruler drives the upper component to rotate, the angular positioning component is used for angular positioning, and the dial indicator is used to detect roundness during rotation. The positioning disc is used for positioning the end face and the inner circle of the part. The positioning base plate is connected to the part by a pressure plate, etc. After clamping and positioning, it is transferred to the worktable of the machine tool along with the tooling. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide an automated flexible contact-type hole axis detection and alignment device and method.

[0007] An automated flexible contact-type hole axis detection and alignment device provided by the present invention includes:

[0008] 1. Length gauge mounting bracket; 2. Probe quick-change adapter plate; 3. Flexible compensation device; 4. Proximity switch; 5. Axial floating mechanism; 6. Flexible compensation device mounting base plate; 7. Proximity switch mounting seat; 8. Base; 9. Length gauge; 10. Probe; and 11. Ear-shaped boss.

[0009] The length gauge mounting bracket 1 is connected to the base 8; the length gauge mounting bracket 1 has a plurality of ear-shaped protrusions 11 with mounting holes on its front and back surfaces for mounting a plurality of length gauges 9.

[0010] The probe 10 passes through the length gauge mounting bracket 1 and is connected to the probe quick connection plate 2;

[0011] The upper mounting plate of the flexible compensation device 3 supports the probe quick-connect plate 2 and the probe 10 connected to the probe quick-connect plate 2; the lower mounting plate of the flexible compensation device 3 is connected to the flexible compensation device mounting base plate 6.

[0012] The flexible compensation device mounting base 6 is connected to the floating end of the axial floating mechanism 5; the fixed end of the axial floating mechanism 5 is connected to the base 8.

[0013] The proximity switch 4 is mounted on the proximity switch mounting base 7, the proximity switch mounting base 7 is connected to the base 8, and the proximity switch 4 is connected to the base 8 through the proximity switch mounting base.

[0014] Preferably, the probe rod 10 utilizes the floating feature of the flexible compensation device 3 to achieve translation in the X and Y axis directions under the action of the profile of the measured feature hole, and to deflect at a certain angle or rotate at a certain angle around a preset position on the reverse extension line of the probe rod axis.

[0015] Preferably, there are at least 8 length gauges 9, which are mounted on the front and back sides of the length gauge mounting bracket 1 via the ear-shaped protrusions 11, forming two layers. The two layers of length gauges are arranged in a mirror image, and the length gauges 9 in each layer are symmetrically arranged with the probe axis as the center.

[0016] Preferably, the probe 10 includes a tapered pin section and a cylindrical section; the tapered pin section and the cylindrical section are coaxially connected; the length gauge 9 passes through the ear-shaped boss 11 with mounting holes, so that the ball end of the length gauge is in close contact with the cylindrical section, while retaining a certain amount of movement margin; when the probe 10 is translated or deflected, the end of the length gauge 9 can always contact the cylindrical section due to the action of the internal spring of the length gauge 9.

[0017] Preferably, during the insertion of the probe 10 into the test hole, the hole wall contacts the tapered pin section of the probe 10, causing the probe to translate and deflect; as the insertion depth of the tapered pin section increases, the tapered pin section fully fits the hole wall of the test hole, so that the tapered pin section and the through hole achieve a preset coaxiality.

[0018] Preferably, when the cylindrical segment deviates from its initial calibration position, the ball heads of multiple length gauges slide against the surface of the cylindrical segment and measure the component of the cylindrical segment's deviance along the length gauge axis.

[0019] Preferably, the proximity switch 4 includes multiple proximity switches 4, which are used to detect the distance d between the automated flexible contact hole axis detection and alignment device and the lower surface of the skin workpiece. p Determine whether the probe 10 has been inserted to a reasonable measurement depth;

[0020] d p ≥(l0-l2)·cosΔγ-l f

[0021] Where l0 represents the probe length; l2 represents the tapered pin section length; Δγ represents the current probe axis deflection angle; l f This indicates the amount of float of the axial floating device.

[0022] According to the calibration method of the automated flexible contact hole axis detection and alignment device provided by the present invention, the following steps are performed using the aforementioned automated flexible contact hole axis detection and alignment device:

[0023] Step C1: Clamp the calibration flat metal test plate on the automatic countersinking equipment. The pressure feet of the upper and lower end actuators in the automatic countersinking equipment are fed to complete the double-sided clamping of the metal test plate and level it.

[0024] Step C2: Replace the spindle of the automatic countersinking equipment with a drilling tool of the same diameter as the initial hole, and perform hole drilling on the metal test plate to drill through holes;

[0025] Step C3: Insert the probe rod in the automated flexible contact hole axis detection and alignment device into the through hole. When the tapered pin section of the probe rod is fully in contact with the hole wall, reset the length gauge reading to zero. At this time, the probe rod axis coincides with the tool axis.

[0026] According to the automated flexible contact hole axis detection and alignment method provided by the present invention, the following steps are performed using the aforementioned automated flexible contact hole axis detection and alignment device:

[0027] Step S1: The center position of the lower end face of the pressure foot of the upper end actuator in the automatic countersinking equipment is the TCP point of the automatic countersinking equipment. After the automatic countersinking equipment is positioned to the theoretical position of the initial hole to be countersinked, the pressure feet of the upper and lower end actuators in the automatic countersinking equipment feed to complete the clamping of the skin workpiece. The feed distance L of the upper and lower pressure feet is measured by a grating ruler. t L b ;

[0028] Step S2: The contact-type measuring device integrated within the pressure foot mechanism measures the normal vector of the skin workpiece surface in the coordinate system of the skin workpiece. Measurements are taken and recorded. The angle between the surface normal and the axis vector used for initial hole alignment can be calculated. If the angle exceeds a set threshold, adjustments can be made according to the surface normal.

[0029] Step S3: Based on the feed distance L t Calculate the coordinates of the TCP point in the automatic countersink coordinate system after the pressure foot is fed, and then calculate the coordinates based on the feed distance L. t L b Calculate the skin thickness d at the current TCP point position. Based on the skin thickness, calculate the coordinates of the corresponding position on the other side of the skin in the automatic countersinking machine coordinate system. Based on the machine tool's structural form, obtain the homogeneous transformation matrix of the skin / workpiece coordinate system in the automatic countersinking machine coordinate system.

[0030] Step S4: The automated flexible contact hole axis detection and alignment device feeds upward under the drive of the linear servo device. The tapered pin at the front end of the probe fits against the hole wall and forces the probe to translate and swing. After the proximity switch determines that the probe has been inserted into place, the axis measurement system composed of multiple length gauges measures the axis position and orientation of the cylindrical end of the probe in real time.

[0031] Step S5: Based on the real-time measured length gauge value, the real-time position and direction of the probe axis can be calculated using a calculation method, thereby realizing closed-loop feedback and continuously adjusting the position and attitude of the skin in real time until the hole axis is aligned.

[0032] Preferably, in step S4, the real-time measurement of the axial position and orientation of the cylindrical end of the probe is performed using:

[0033] The preset center of the ball head of the 8 length measuring endpoints is P. i (x i ,y i ,z i ), where i = 1...8, and the approximate point P0(x0,y0,z0) on the cylindrical axis is calculated based on the center of the ball head at the end of the length gauge.

[0034]

[0035] Among them, z i Since the length gauge is fixed upward along the Z-axis, its position in the Z-direction is constant; for a length gauge mounted on the front of the length gauge mounting bracket 1, z i = z1, where i = 1, 2, 3, 4; for a length gauge installed on the opposite side of the length gauge mounting support 1, z i = z2, where i = 5, 6, 7, 8;

[0036] Let P0 be the origin, and let the unit vector of the hole axis be (i,j,k); point P0 points to P. i Point vector P0P i The angle between P and the unit vector of the hole axis is α; i The projection of point P onto the axis of the cylinder e Then the following relationship holds:

[0037]

[0038]

[0039] i 2 +j 2 +k 2 =1 (4)

[0040] P e P i Let E be the actual radius of the fitted cylinder, and the error between it and the true radius of the cylinder be expressed as:

[0041] Ε=|P e P i |-Rr

[0042] R'=R+r

[0043] Ε=|P e P i |-R' (5)

[0044] Where R represents the radius of the cylindrical section of the probe, and r represents the radius of the ball head of the length gauge;

[0045] make:

[0046]

[0047] After expanding the error formula:

[0048]

[0049] Transform the error equation; let the error equation be:

[0050] Ε=|P e P i |2 -R' 2

[0051] Ε=a i 2 +b i 2 +c i 2 -(i·a i +j·b i +k·c i ) 2 -R' 2 (8)

[0052] The i, j, and k values ​​when E is minimized are obtained using the least squares method, which are the orientations of the cylinder's axis. Combined with the starting point P0(x0,y0,z0), the cylinder's axis Ac in space is fitted.

[0053] Among them, the positions of the eight length gauges relative to the base in the Z direction are fixed, while the position of the flexible compensation hole axis borehole probe measurement and alignment device in the end is measured by an absolute grating ruler, and the spatial expression of the cylindrical axis is obtained in the coordinate system of the automatic countersinking machine tool after coordinate transformation.

[0054] Preferably, step S5 includes:

[0055] Define the plane determined by the pressure foot end face on the automatic countersink as the local cutting plane of the lower surface of the workpiece at the current machining position, and define the intersection point P of the plane with the tool axis. T Point P is the intersection of the target adjustment position and the probe axis. T Current position; tool axis V T Adjust the attitude of the target, probe axis V T This is the current stance;

[0056] Perform hole axis alignment while keeping the current TCP point unchanged, i.e., P. T The position remains unchanged; the adjustment goal is to make the probe cylinder axis vector V... T With the tool axis vector V T 'Equal, V T With V T The included angle is Δγ. Using the inverse kinematics of the equipment, the required adjustment amount for each axis of the equipment can be determined.

[0057] Δγ=arccos(V T gV T ') (9)

[0058] Waiting for V T =V T After ', P T Point and P T The point position error is (x t -xt ', y t -y t '), control the machine tool to move the skin (x t '-x t y t '-y t ), until the measured P T Point and P T The point position error is less than the threshold (x) h ,y h This ultimately results in the workpiece's current pose (P). T V T ) and target pose (P T ',V T ')equal.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] 1. This invention provides a device and method for measuring the initial hole axis on a skin workpiece with high precision and assisting in alignment. It adopts a contact-type indirect measurement method and utilizes the fit between the tapered pin and the hole to obtain good coaxiality. At the same time, it can also overcome the influence of hole diameter error (hole fit tolerance H9).

[0061] 2. This invention is adapted to the characteristics of small aspect ratio (hole diameter is greater than thickness) of initial holes on thin-walled workpieces, and its applicable scope covers various skin thicknesses and various hole diameters;

[0062] 3. The invention incorporates flexible design in many places and is equipped with proximity switches to protect the expensive aircraft skin from damage.

[0063] 4. The probe rod of this invention is easy to install and can be quickly disassembled and replaced using a quick-change device, which can handle the initial hole inspection of different hole diameters;

[0064] 5. This invention greatly improves production efficiency while ensuring that the processing accuracy meets the requirements. Attached Figure Description

[0065] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0066] Figure 1 This is a schematic diagram of an automated flexible contact hole axis detection and alignment device.

[0067] Figure 2 This is an exploded view of an automated flexible contact-type hole axis detection and alignment device.

[0068] Figure 3 This is a diagram showing the relationship between the length gauge and the probe.

[0069] Figure 4 This is a schematic diagram illustrating the relationship between the length gauge and the probe's movement and the principle of measurement data.

[0070] Figure 5 This is a schematic diagram of an automated flexible contact hole axis detection and alignment device.

[0071] Figure 6 This is a schematic diagram illustrating the working principle of an automated flexible contact-type hole axis detection and alignment device.

[0072] Figure 7 To fit the relationship between the cylinder radius and the actual cylinder radius.

[0073] Figure 8 This is a schematic diagram of the expansion pin structure.

[0074] Figure 9 This is a schematic diagram of a flexible compensation module consisting of a planar guide rail slider and a ball joint. Detailed Implementation

[0075] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0076] Example 1

[0077] An automated flexible contact-type hole axis detection and alignment device provided by the present invention, such as Figure 1-3 As shown, it includes:

[0078] 1. Length gauge mounting bracket; 2. Probe quick-change adapter plate; 3. Flexible compensation device; 4. Proximity switch; 5. Axial floating mechanism; 6. Flexible compensation device mounting base plate; 7. Proximity switch mounting seat; 8. Base; 9. Length gauge; 10. Probe; and 11. Ear-shaped boss.

[0079] The length gauge mounting bracket 1 is connected to the base 8; the length gauge mounting bracket 1 has a plurality of ear-shaped protrusions 11 with mounting holes on its front and back surfaces for mounting a plurality of length gauges 9.

[0080] The probe 10 passes through the length gauge mounting bracket 1 and is connected to the probe quick connection plate 2;

[0081] The upper mounting plate of the flexible compensation device 3 supports the probe quick-connect plate 2 and the probe 10 connected to the probe quick-connect plate 2; the lower mounting plate of the flexible compensation device 3 is connected to the flexible compensation device mounting base plate 6.

[0082] The flexible compensation device mounting base 6 is connected to the floating end of the axial floating mechanism 5; the fixed end of the axial floating mechanism 5 is connected to the base 8.

[0083] The proximity switch 4 is mounted on the proximity switch mounting base 7, the proximity switch mounting base 7 is connected to the base 8, and the proximity switch 4 is connected to the base 8 through the proximity switch mounting base.

[0084] Specifically, after the flexible compensation device 3 is released from the locking state, the free end of the disk can freely translate, swing and rotate within a limited range; giving the automated equipment a certain degree of flexibility and improving safety.

[0085] For example, the flexible compensation device 3 includes a flexible compensation device composed of a planar guide rail slider and a ball joint, which can increase the stroke of flexible compensation in the translation and deflection directions, such as... Figure 9 As shown.

[0086] Specifically, the axial floating mechanism 5 can ensure that the measuring mechanism has a certain degree of flexibility when the probe 10 is inserted into the hole being measured, so as to avoid accidental damage to the workpiece.

[0087] Specifically, the probe rod 10 utilizes the floating feature of the flexible compensation device 3 to achieve translation in the X and Y axes under the action of the profile of the measured feature hole, and to deflect at a certain angle at about 1 / 3 of the probe rod length along the reverse extension line of the probe rod axis, or to complete a certain angle rotation around the probe rod's own axis.

[0088] Specifically, the length gauges 9 are mounted on the front and back sides of the length gauge mounting bracket 1 via the ear-shaped protrusions 11, forming two layers. The two layers of length gauges are mirror images of each other, and the length gauges 9 in each layer are symmetrically arranged with the probe axis as the center. For example, there are at least 8 length gauges 9 (9a to 9h), and the length gauges 9a to 9h are arranged in two layers, each layer being arranged in an "X" shape.

[0089] Specifically, the probe 10 includes a tapered pin section and a cylindrical section. The tapered pin section, located at the front end of the probe 10, is a small-tapered pin with a large chamfer that matches the diameter of the initial hole to be measured. It serves as a guide when inserted into the initial hole, accommodating a maximum hole-making error of Φ0.1mm. The cylindrical section, located at the rear end of the probe 10, is thicker, and the tapered pin section is coaxially connected to the cylindrical section; for example, an expansion pin. Figure 8 As shown; the length gauge 9 passes through the ear-shaped boss with mounting holes, so that the ball end of the length gauge is in close contact with the cylindrical section, while retaining a certain amount of movement margin; when the probe 10 is translated or deflected, the end of the length gauge 9 can always contact the cylindrical section.

[0090] Specifically, during the process of inserting the tapered pin section of the probe rod 10 into the test hole, the hole wall contacts the tapered pin section of the probe rod 10 and forces the floating probe rod to translate and deflect; as the insertion depth of the tapered pin section increases, the tapered pin section fully fits the hole wall of the test hole, so that the tapered pin section and the through hole achieve a high degree of coaxiality.

[0091] Specifically, when the cylindrical segment deviates from its initial calibration position, the ball heads of multiple length gauges slide against the surface of the cylindrical segment and measure the component of the cylindrical segment's deviation along the length gauge axis.

[0092] Specifically, the proximity switches 4 include multiple switches, such as 4a and 4b; the multiple proximity switches 4 are used to detect the distance d between the automated flexible contact hole axis detection and alignment device and the lower surface of the skin workpiece. p Determine whether the probe (10) is inserted to a reasonable measurement depth;

[0093] d p ≥(l0-l2)·cosΔγ-l f

[0094] Where l0 represents the probe length; l2 represents the tapered pin section length; Δγ represents the current probe axis deflection angle; l f This indicates the amount of float of the axial floating device.

[0095] Redundancy is designed to improve system reliability and prevent damage to the workpiece caused by the failure of a single proximity switch.

[0096] Taking the countersinking process on the initial hole of the skin workpiece as an example:

[0097] During countersinking, to enhance the rigidity of the thin-walled structure and ensure countersink quality, the upper and lower sides of the skin need to be clamped around the countersink location. This is typically achieved through pressure foot structures on the upper and lower end effectors of automated processing equipment. To avoid the influence of skin deformation on the hole axis, when using the automated flexible compensation hole axis probing and alignment device provided by this invention for measurement and auxiliary adjustment, the skin should maintain the same clamping state as during countersinking.

[0098] To ensure that the coaxiality of the final countersink and the initial hole meets the requirements of aviation standards, it is necessary to measure the hole position and axial direction of the initial hole and compensate for it in the positioning of the countersink tool axis.

[0099] According to the calibration method of the automated flexible contact hole axis detection and alignment device provided by the present invention, the following steps are performed using the aforementioned automated flexible contact hole axis detection and alignment device:

[0100] Step C1: Clamp the calibration flat metal test plate on the automatic countersinking equipment. The pressure feet of the upper and lower end actuators in the automatic countersinking equipment are fed to complete the double-sided clamping of the metal test plate and level it.

[0101] Step C2: Replace the spindle of the automatic countersinking equipment with a drilling tool of the same diameter as the initial hole, and perform hole drilling on the metal test plate to drill through holes;

[0102] Step C3: Insert the probe rod in the automated flexible contact hole axis detection and alignment device into the through hole. When the tapered pin section of the probe rod is fully in contact with the hole wall, reset the length gauge reading to zero. At this time, the probe rod axis coincides with the tool axis.

[0103] According to the present invention, an automated flexible contact hole axis detection and alignment method is provided, which uses the aforementioned automated flexible contact hole axis detection and alignment device to perform the following steps: Figure 5 As shown.

[0104] Step S1: The center position of the lower end face of the pressure foot of the upper end actuator in the automatic countersinking equipment is the TCP point of the automatic countersinking equipment. After the automatic countersinking equipment is positioned to the theoretical position of the initial hole to be countersinked, the pressure feet of the upper and lower end actuators in the automatic countersinking equipment feed to complete the clamping of the skin workpiece. The feed distance L of the upper and lower pressure feet is measured by a grating ruler. t L b ;

[0105] Step S2: The contact-type measuring device integrated within the pressure foot mechanism measures the normal vector of the skin workpiece surface in the coordinate system of the skin workpiece. Measurements are taken and recorded. The angle between the surface normal and the axis vector used for initial hole alignment can be calculated. If the angle exceeds a set threshold, adjustments can be made according to the surface normal.

[0106] Step S3: Based on the feed distance L t Calculate the coordinates of the TCP point in the automatic countersink coordinate system after the pressure foot is fed, and then calculate the coordinates based on the feed distance L. t L b Calculate the skin thickness d at the current TCP point position. Based on the skin thickness, calculate the coordinates of the corresponding position on the other side of the skin in the automatic countersinking machine coordinate system. Based on the machine tool's structural form, obtain the homogeneous transformation matrix of the skin / workpiece coordinate system in the automatic countersinking machine coordinate system.

[0107] Step S4: The automated flexible contact hole axis detection and alignment device feeds upward under the drive of a linear servo device. The tapered pin at the front end of the probe fits against the hole wall, forcing the probe to translate and swing. During the translation and swing of the probe, the eight length gauges extend or shorten with the movement of the probe, and their ball heads always remain in contact with the probe surface. Taking the front layer of the length gauge mounting support as an example (see...) Figure 4 After completing the automated flexible contact hole axis detection calibration as described in claim 8, the positions of the length gauge ball head can be recorded as P1(r,0), P2(0,-r), P3(-r,0), P4(0,r). After the probe moves and swings, the new positions of the length gauge ball head can be recorded as P1'(r+reading,0), P2'(0,-r+reading), P3'(-r-reading,0), P4'(0,r-reading), assuming the reading is positive when the displacement gauge extends. Similarly, the zero point positions P5 to P8 of the length gauge ball head on the reverse side of the length gauge mounting support are the same as the new positions P5' to P8' of the length gauge ball head after the probe moves and swings.

[0108] Step S5: Based on the real-time measured length gauge value, the real-time position and direction of the probe axis can be calculated using a calculation method, thereby realizing closed-loop feedback and continuously adjusting the position and attitude of the skin in real time until the hole axis alignment is completed.

[0109] Specifically, the calculation method for the axial position and orientation of the cylindrical end of the probe in step S4 is as follows:

[0110] The preset center of the ball head of the 8 length measuring endpoints is P. i (x i ,y i ,z i ), where i = 1...8, and the approximate point P0(x0,y0,z0) on the cylindrical axis is calculated based on the center of the ball head at the end of the length gauge.

[0111]

[0112] Among them, z i Since the length gauge is fixed upward along the Z-axis, its position in the Z-direction is constant; for a length gauge mounted on the front of the length gauge mounting bracket 1, z i = z1, where i = 1, 2, 3, 4; for a length gauge installed on the opposite side of the length gauge mounting support 1, z i = z2, where i = 5, 6, 7, 8;

[0113] Let P0 be the origin, and let the unit vector of the hole axis be (i,j,k); point P0 points to P. i Point vector P0P i The angle between P and the unit vector of the hole axis is α; iThe projection of point P onto the axis of the cylinder e Then the following relationship holds:

[0114]

[0115]

[0116] i 2 +j 2 +k 2 =1 (4)

[0117] P e P i The actual fitted radius of the cylinder, and the error E between it and the true radius of the cylinder, are expressed as: (e.g.) Figure 7 As shown,

[0118] Ε=|P e P i |-Rr

[0119] R'=R+r

[0120] Ε=|P e P i |-R' (5)

[0121] Where R represents the radius of the cylindrical section of the probe, and r represents the radius of the ball head of the length gauge;

[0122] make:

[0123]

[0124] After expanding the error formula:

[0125]

[0126] Transform the error equation; let the error equation be:

[0127] Ε=|P e P i | 2 -R' 2

[0128] Ε=a i 2 +b i 2 +c i 2 -(i·a i +j·b i +k·c i ) 2 -R' 2 (8)

[0129] Since there are no radicals, the correlation between the six parameters x0, y0, z0, i, j, and k is greatly reduced. As a result, the quadratic term in the error equation is very small during linearization and can be discarded during adjustment. This significantly reduces the sensitivity of the parameters to the choice of initial values.

[0130] The values ​​of x0, y0, z0, i, j, and k when E is minimized are obtained using the least squares method, which are the orientations of the cylinder's axis. Combined with the starting point P0(x0, y0, z0), the cylinder's axis Ac in space is fitted.

[0131] Among them, the positions of the eight length gauges relative to the base in the Z direction are fixed, while the position of the flexible compensation hole axis borehole probe measurement and alignment device in the end is measured by an absolute grating ruler. After coordinate transformation, the spatial expression of the cylindrical axis is obtained in the coordinate system ${MACHINE} of the automatic countersinking machine tool.

[0132] Alternatively, for the detection method of the initial hole axis, a method is adopted to fit the center of the circle using four length gauges on the upper and lower layers respectively, and the probe / initial hole axis is determined by connecting the two center lines.

[0133] Specifically, step S5 includes: Figure 6 As shown,

[0134] Define the plane determined by the pressure foot end face on the automatic countersink as the local cutting plane of the lower surface of the workpiece at the current machining position, and define the intersection point P of the plane with the tool axis. T Point P is the intersection of the target adjustment position and the probe axis (hole axis). T Current position; tool axis V T Adjust the attitude for the target, probe axis (hole axis) V T This is the current stance.

[0135] The first step is to align the hole axis while keeping the current TCP point unchanged, i.e., P. T The position remains unchanged; the adjustment goal is to make the probe cylinder axis vector V... T With the tool axis vector V T 'Equal, V T With V T The included angle is Δγ. Using the inverse kinematics of the equipment, the required adjustment amount for each axis of the equipment can be determined.

[0136] Δγ=arccos(V T gV T ') (9)

[0137] Step two, wait for V T =V T After ', P T Point and P T The point position error is (xt -x t ', y t -y t '), control the machine tool to move the skin (x t '-x t y t '-y t ), until the measured P T Point and P T The point position error is less than the threshold (x) h ,y h This ultimately results in the workpiece's current pose (P). T V T ) and target pose (P T ',V T ')equal.

[0138] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0139] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An automated flexible contact-type hole axis detection and alignment device, characterized in that, include: Length gauge mounting bracket (1), probe quick-change adapter plate (2), flexible compensation device (3), proximity switch (4), axial floating mechanism (5), flexible compensation device mounting base plate (6), proximity switch mounting seat (7), base (8), length gauge (9), probe (10) and ear-shaped boss (11). The length gauge mounting bracket (1) is connected to the base (8); multiple ear-shaped protrusions (11) with mounting holes are provided on the front and back opposite surfaces of the length gauge mounting bracket (1) for mounting multiple length gauges (9). The probe (10) passes through the length gauge mounting bracket (1) and is connected to the probe quick-connect plate (2); The upper mounting plate of the flexible compensation device (3) supports the probe quick-connect plate (2) and the probe (10) connected to the probe quick-connect plate (2); the lower mounting plate of the flexible compensation device (3) is connected to the mounting base plate (6) of the flexible compensation device. The flexible compensation device mounting base plate (6) is connected to the floating end of the axial floating mechanism (5); the fixed end of the axial floating mechanism (5) is connected to the base (8). The proximity switch (4) is mounted on the proximity switch mounting base (7), which is connected to the base (8). The proximity switch (4) is connected to the base (8) through the proximity switch mounting base.

2. The automated flexible contact hole axis detection and alignment device according to claim 1, characterized in that, The probe (10) utilizes the floating feature of the flexible compensation device (3) to achieve translation in the X and Y axes under the action of the profile of the measured feature hole, and to deflect at a certain angle or rotate at a certain angle around the probe's own axis at a preset position on the reverse extension line of the probe axis.

3. The automated flexible contact hole axis detection and alignment device according to claim 1, characterized in that, There are at least 8 length gauges (9). The length gauges (9) are installed on the front and back sides of the length gauge mounting bracket (1) respectively through the ear-shaped protrusions (11) to form two layers. The two layers of length gauges are set in mirror image. The length gauges (9) in each layer are symmetrically arranged with the probe axis as the center.

4. The automated flexible contact hole axis detection and alignment device according to claim 1, characterized in that, The probe (10) includes a tapered pin section and a cylindrical section; the tapered pin section and the cylindrical section are coaxially connected; the length gauge (9) passes through the ear-shaped boss (11) with mounting holes, so that the ball end of the length gauge is in close contact with the cylindrical section and retains a certain amount of movement margin; when the probe (10) is translated or deflected, the end of the length gauge (9) can always contact the cylindrical section due to the action of the internal spring of the length gauge (9).

5. The automated flexible contact hole axis detection and alignment device according to claim 4, characterized in that, During the process of inserting the probe (10) into the test hole, the hole wall contacts the tapered pin section of the probe (10) and causes the probe to translate and deflect; as the insertion depth of the tapered pin section increases, the tapered pin section fully fits the hole wall of the test hole, so that the tapered pin section and the through hole achieve the coaxiality of the preset state.

6. The automated flexible contact hole axis detection and alignment device according to claim 4, characterized in that, When the cylindrical segment deviates from its initial calibration position, the ball heads of multiple length gauges slide against the surface of the cylindrical segment and measure the component of the cylindrical segment's deviance along the length gauge axis.

7. The automated flexible contact hole axis detection and alignment device according to claim 1, characterized in that, The proximity switches (4) include multiple ones, which are used to detect the distance between the automated flexible contact hole axis detection and alignment device and the lower surface of the skin workpiece. Determine whether the probe (10) is inserted to a reasonable measurement depth; in, Indicates the length of the probe; Indicates the length of the tapered pin section; Axis deflection angle; This indicates the amount of float of the axial floating device.

8. An automated flexible contact-type hole axis detection and calibration method, characterized in that, The automated flexible contact hole axis detection and alignment device according to any one of claims 1-7 is calibrated using the following steps: Step C1: Clamp the calibration flat metal test plate on the automatic countersinking equipment. The pressure feet of the upper and lower end actuators in the automatic countersinking equipment are fed to complete the double-sided clamping of the metal test plate and level it. Step C2: Replace the spindle of the automatic countersinking equipment with a drilling tool of the same diameter as the initial hole, and perform hole drilling on the metal test plate to drill through holes; Step C3: Insert the probe rod in the automated flexible contact hole axis detection and alignment device into the through hole. After the tapered pin section of the probe rod is fully in contact with the hole wall, reset the length gauge reading to zero. The current probe rod axis coincides with the tool axis.

9. An automated flexible contact-type hole axis detection and alignment method, characterized in that, The automated flexible contact hole axis detection and alignment device according to any one of claims 1-7 performs the following steps: Step S1: The center position of the lower end face of the pressure foot of the upper end actuator in the automatic countersinking equipment is the TCP point of the automatic countersinking equipment. After the automatic countersinking equipment is positioned to the theoretical position of the initial hole to be countersinked, the pressure feet of the upper and lower end actuators in the automatic countersinking equipment feed to complete the clamping of the skin workpiece. The feed distance of the upper and lower pressure feet is measured by a grating ruler. , ; Step S2: The contact-type measuring device integrated within the pressure foot mechanism measures the normal vector of the skin workpiece surface in the coordinate system of the skin workpiece. Measure and record, calculate the angle between the surface normal and the axis vector for initial hole alignment. If the angle exceeds the set threshold, adjust according to the surface normal. Step S3: Based on the feed distance Calculate the coordinates of the TCP point in the automatic countersinking machine coordinate system after the pressure foot is fed, and then calculate based on the feed distance. , Calculate the skin thickness d at the current TCP point position. Based on the skin thickness, calculate the coordinates of the corresponding position on the other side of the skin in the automatic countersinking machine coordinate system. Based on the machine tool's structural form, obtain the homogeneous transformation matrix of the skin / workpiece coordinate system in the automatic countersinking machine coordinate system. ; Step S4: The automated flexible contact hole axis detection and alignment device feeds upward under the drive of the linear servo device. The tapered pin at the front end of the probe fits against the hole wall and forces the probe to translate and swing. After the proximity switch determines that the probe has been inserted into place, the axis measurement system composed of multiple length gauges measures the axis position and orientation of the cylindrical end of the probe in real time. Step S5: Based on the real-time measured length gauge value, use the calculation method to calculate the real-time position and direction of the probe axis, thereby realizing closed-loop feedback and continuously adjusting the position and attitude of the skin in real time until the hole axis is aligned.

10. The automated flexible contact hole axis detection and alignment method according to claim 9, characterized in that, In step S4, the real-time measurement of the axial position and orientation of the cylindrical end of the probe is performed using: The preset center of the ball head of the 8 length measuring endpoints is Where i = 1...8, the approximate point on the cylinder axis is calculated based on the center of the ball head at the end of the length gauge. ; （1） in, Since the length gauge is fixed upward along the Z-axis, its position in the Z-direction is constant; for a length gauge mounted on the front of the length gauge mounting bracket (1), the z-axis position is constant. i =z1, where i=1,2,3,4; for a length gauge set on the opposite side of the length gauge mounting support (1), z i =z2, where i=5,6,7,8; Let P0 be the origin, and let the unit vector of the hole axis be (i,j,k); point P0 points to P. i Point vector P0P i The angle between P and the unit vector of the hole axis is α; i The projection of point P onto the axis of the cylinder e Then the following relationship holds: （2） （3） （4） P e P i Let E be the actual radius of the fitted cylinder, and the error between it and the true radius of the cylinder be expressed as: （5） Where R represents the radius of the cylindrical section of the probe, and r represents the radius of the ball head of the length gauge; make: （6） After expanding the error formula: （7） Transform the error equation; let the error equation be: （8） The i, j, and k values ​​when E is minimized are obtained using the least squares method, which are the orientations of the cylinder's axis. Combined with the starting point P0 (x0, y0, z0), the cylinder's axis Ac in space is fitted. Among them, the positions of the eight length gauges relative to the base in the Z direction are fixed, while the position of the flexible compensation hole axis borehole probe measurement and alignment device in the end is measured by an absolute grating ruler, and the spatial expression of the cylindrical axis is obtained in the coordinate system of the automatic countersinking machine tool after coordinate transformation.

11. The automated flexible contact hole axis detection and alignment method according to claim 9, characterized in that, Step S5 includes: Define the plane determined by the pressure foot end face on the automatic countersink as the local cutting plane of the lower surface of the workpiece at the current machining position, and define the intersection point P of the plane with the tool axis. T Point P is the intersection of the target adjustment position and the probe axis. T Current position; tool axis V T Adjust the attitude of the target, probe axis V T This is the current stance; Perform hole axis alignment while keeping the current TCP point unchanged, i.e., P. T The position remains unchanged; the adjustment goal is to make the probe cylinder axis vector V... T With the tool axis vector V T 'Equal, V T With V T The included angle is By using the inverse kinematics of the equipment, the required adjustment amount for each axis of the equipment can be determined; （9） Waiting for V T = V T After ', P T Point and P T The point position error is (x t -x t ', y t -y t '), control the machine tool to move the skin (x t '-x t y t '-y t ), until the measured P T Point and P T The point position error is less than the threshold (x) h ,y h ), ultimately resulting in the workpiece's current pose (P) T V T ) and target pose (P T ',V T ')equal.

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