Milling robot tool setting system and method for trepanning of large spherical shell

Abstract

The invention discloses a milling robot tool setting system and method for large-scale spherical shell tapping, solves the problem that the first cutting amount is too large when a large-scale spherical shell is tapped, and belongs to the field of spherical shell machining. According to the tool setting system, a laser range finder and an electric spindle are installed on a mechanical arm of an industrial robot at the same time, the laser range finder is used for measuring the distance to the surface of a spherical shell, and a milling cutter is clamped on the electric spindle; the tool setting method comprises the steps of setting tool setting points, generating a tool setting program according to coordinates of the tool setting points, operating the tool setting program, obtaining the distance to the position of each tool setting point on the surface of the spherical shell through a laser range finder, obtaining a distance set L, and calculating the minimum difference value delta =-(min (L)-H-delta Z), delta is the coordinate of the first cutting position in the axis direction of the tool under a hole milling workpiece coordinate system {WP}, tool setting is completed, H represents the height of a tool setting safety plane, and delta Z is the difference value of the tool coordinate system {TCP} and the laser range finder coordinate system {DM} in the axis direction of the tool.

Description

Technical Field

[0001] The invention relates to a milling robot tool setting system and method for opening a large spherical shell, and belongs to the field of spherical shell processing. Background Art

[0002] Industrial robots are gradually being used in the manufacturing system of large structural parts due to their multiple degrees of freedom and easy integration of multi-sensory intelligent sensors to form high-performance manufacturing equipment. Reasonable planning and use of intelligent sensors can effectively give play to the performance advantages of industrial robots, improve productivity, expand the flexibility of the system, and enable them to play a more effective role in the field of high-precision manufacturing.

[0003] During the processing of large spherical shells, the industrial robot 6 is installed several meters above the ground to complete the multi-hole processing task on the surface of the spherical shell. The existing technical solution uses manual tool setting, which requires the operator to have very high technical requirements. In addition, the error of human eye tool setting is usually at the millimeter level. In addition to the problem of large tool setting error, the operation process requires personnel to operate the robot while relying on the overhead crane to complete it, which makes it difficult to achieve automated tool setting safely and conveniently. In addition, for the milling of large spherical shells, there is non-uniformity on its outer surface, that is, the spherical shell is uneven, and it is necessary to perform multi-point and multiple tool setting tasks. The manual tool setting process is complicated, and improper tool setting parameters will cause the first tool cutting amount to be too large, thereby causing tool damage or equipment downtime. Therefore, robot automated tool setting has become the preferred choice for industrial robots to perform large spherical shell hole opening tasks. In order to realize the rapid and automated tool setting task, the first thing to solve is to automate and quickly set the tool by integrating intelligent sensors at the end of the industrial robot. By integrating intelligent sensors at the end of the industrial robot, the tool setting process can be simplified to improve efficiency, improve tool setting accuracy, and reduce labor costs.

[0004] Non-contact tool setting solutions are widely used in machine tool processing, and industrial robots used for processing tasks are also suitable for the promotion of this type of tool setting method. Therefore, non-contact intelligent sensors such as laser rangefinders are particularly suitable for high-precision and efficient robot processing tool setting tasks. Compared with machine vision tool setting solutions, this method has strong resistance to environmental interference and good stability. Therefore, integrating the laser rangefinder into the robot processing system can meet the tool setting task requirements for milling and opening holes on the surface of large spherical shells, and can realize fast and automated tool setting. At present, the process of automated tool setting still has the problem that when the robot mills and opens holes, the first cutting position is difficult to determine, and the tool breakage and equipment downtime are caused by the excessive first cutting amount due to the uneven surface of the large spherical shell. Summary of the invention

[0005] Aiming at the problem that the first cutting amount is too large when setting the tool when drilling a hole in a large spherical shell, the present invention provides a milling robot tool setting system and method for drilling a hole in a large spherical shell.

[0006] A milling robot tool setting system for opening a hole in a large spherical shell of the present invention comprises a laser rangefinder, an industrial robot and an electric spindle;

[0007] The laser rangefinder and the electric spindle are installed on the manipulator of the industrial robot at the same time. The laser rangefinder is used to measure the distance to the surface of the ball shell, and the milling cutter is clamped on the electric spindle.

[0008] The control system of the industrial robot is used to calculate the coordinates of the tool setting points according to the number of tool setting points and the hole size of the hole to be milled, generate a tool setting program according to the tool setting point coordinates, run the tool setting program, obtain the distance to each tool setting point position on the surface of the spherical shell through a laser rangefinder, obtain a distance set L, calculate the minimum difference Δ=-(min(L)-H-ΔZ), Δ is used as the coordinate of the first cutting position in the tool axis direction in the milling hole workpiece coordinate system {WP}, complete the tool setting, H represents the height of the tool setting safety plane, ΔZ is the difference between the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM} in the tool axis direction.

[0009] As a preferred method, the difference ΔZ is obtained by:

[0010] According to the pose of the robot flange coordinate system {R6} and the tool coordinate system {TCP}, the homogeneous transformation matrix between the robot flange coordinate system {R6} and the tool coordinate system {TCP} is obtained.

[0011] According to the installation position of the laser rangefinder, the homogeneous transformation matrix between the robot flange coordinate system {R6} and the laser rangefinder coordinate system {DM} is obtained Further determine the homogeneous transformation matrix between the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM} The difference ΔZ between the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM} in the tool axis direction is obtained.

[0012] Preferably, a laser rangefinder is arranged on the side of the electric spindle, and the light beam direction of the laser rangefinder is coaxial with the milling cutter clamped by the electric spindle.

[0013] Preferably, H is the distance of the highest point on the surface of the spherical shell measured by a laser rangefinder.

[0014] As a preferred method, the method for calculating the tool setting point coordinates is:

[0015]

[0016] Where X i,point Y i,point Z i,point Respectively represent the coordinate values ​​of the X, Y, and Z axes of the i-th tool setting point, R holerepresents the radius of the hole to be milled, n represents the number of tool setting points, N * Represents a positive integer.

[0017] Preferably, when the tool setting program is run and the distance to each tool setting point position on the surface of the spherical shell is obtained by a laser rangefinder, a set time is paused at each tool setting point position.

[0018] The present invention also provides a tool setting method for a milling robot used for opening a hole in a large spherical shell. The method is implemented based on a tool setting system, which includes a laser rangefinder, an industrial robot and an electric spindle. The laser rangefinder and the electric spindle are simultaneously installed on the manipulator of the industrial robot, the laser rangefinder is used to measure the distance to the surface of the spherical shell, and the milling cutter is clamped on the electric spindle.

[0019] The tool setting method comprises:

[0020] Determine the conversion relationship between each coordinate system, and obtain the difference ΔZ between the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM} in the tool axis direction;

[0021] Calculate the coordinates of the tool setting points according to the number of tool setting points and the hole size of the hole to be milled;

[0022] Generate a tool setting program based on the tool setting point coordinates, run the tool setting program, obtain the distance to each tool setting point position on the surface of the spherical shell through the laser rangefinder, get the distance set L, calculate the minimum difference Δ=-(min(L)-H-ΔZ), Δ is used as the coordinate of the first cutting position in the tool axis direction in the milling hole workpiece coordinate system {WP}, and complete the tool setting. H represents the height of the tool setting safety plane.

[0023] The beneficial effect of the present invention is that the present invention avoids the problem of tool breakage and equipment downtime caused by excessive first cutting amount due to the non-uniform surface of the large spherical shell, and realizes accurate and reliable automatic rapid tool setting. The present invention can improve the reliability and stability of tool setting and effectively improve the tool setting efficiency. The method is a non-contact method and also ensures the safety of the tool setting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the tool alignment for the industrial robot milling the ball shell surface hole;

[0025] Figure 2 The coordinate transfer relationship diagram between the coordinate systems used for tool setting;

[0026] Figure 3 Diagram of the method for determining the tool coordinate system in the tool setting program

[0027] Figure 4 A schematic diagram of the tool setting point position for setting the circular hole to be milled;

[0028] Figure 5 The calculation principle diagram of tool setting using laser rangefinder;

[0029] Figure 6 Tool setting result diagram. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0033] This embodiment aims to solve the problems of low precision, high risk and complex process brought about by the manual tool setting method in the prior art. The method is mainly implemented through two steps. The first is to determine the conversion relationship between the various coordinate systems, that is, through the tool coordinate system and the rangefinder coordinate system under the flange coordinate system, calculate the relationship between the tool coordinate system and the rangefinder coordinate system, offset the rangefinder coordinate system and set it as the tool coordinate system to generate a tool setting program, and run the tool setting program to calculate the minimum difference between the distance from the laser rangefinder to the surface of the tool setting point ball shell and the installation distance of the laser rangefinder. This embodiment solves the problem of difficulty in determining the first cutting position when the robot is milling a hole. By integrating the laser rangefinder on the industrial robot to realize automated tool setting tasks, considerable efficiency advantages are achieved.

[0034] The milling robot tool setting method for opening a large spherical shell in this embodiment is implemented based on a tool setting system, which includes a laser rangefinder 5, an industrial robot 6 and an electric spindle 4; Figure 1 As shown, the laser rangefinder 5 and the electric spindle 4 are simultaneously installed on the manipulator of the industrial robot 6, the laser rangefinder 5 is used to measure the distance to the surface of the spherical shell, and the milling cutter 3 is clamped on the electric spindle 4; the tool setting system mills a hole on the spherical shell 1; in this embodiment, the laser rangefinder 5 is integrated on the side of the electric spindle, and the beam direction of the laser rangefinder 5 is coaxial with the milling cutter 3 clamped by the electric spindle 4; the tool setting method of this embodiment includes:

[0035] Step 1. When the industrial robot 6 mills the hole on the surface of the ball shell, in order to facilitate the subsequent setting of parameters in the program, several coordinate systems are first clarified: the robot base coordinate system {BASE}, the workpiece coordinate system {WP} of the hole to be milled, the flange coordinate system {R6}, the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM}, so as to determine the transfer relationship between the coordinate systems; these coordinate systems are obtained by measuring and calibrating the laser tracker;

[0036] The workpiece coordinate system of the hole to be milled is determined in the spherical shell center coordinate system. According to the longitude and latitude of the hole on the spherical shell and the radius of the spherical shell, the workpiece coordinate system position is calculated. The calculation method is as follows:

[0037]

[0038] Where X hole , Y hole , Z hole is the origin of the workpiece coordinate system in the spherical center coordinate system. The Z direction of the workpiece coordinate system is outward along the radius of the sphere. The X direction is the tangent of the meridian pointing to the North Pole. R is the radius of the spherical shell. α hole is the longitude of the center of hole 2 to be milled, β hole It is the latitude of the center position of the hole 2 to be milled. The north latitude is defined as a positive value and the south latitude is a negative value.

[0039] The robot base coordinate system and the robot flange coordinates are both established by using the robot single joint swing acquisition fitting;

[0040] Step 2: According to the position and posture of the workpiece coordinate system and the robot base coordinate system, calculate the homogeneous transformation matrix between the workpiece coordinate system on the spherical shell and the robot base coordinate system According to the position and posture of the robot flange coordinate system and the tool coordinate system, the homogeneous transformation matrix between the robot flange coordinate system and the tool coordinate system is obtained According to the installation position of the laser rangefinder 5, the homogeneous transformation matrix between the robot flange coordinate system and the rangefinder coordinate system is obtained according to and Further determine the homogeneous transformation matrix between the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM} The difference ΔZ between the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM} in the tool axis direction is obtained. The laser rangefinder coordinate system is offset by the difference in the Z direction of the tool coordinate system to finally determine the tool coordinate system {DMP} used in the final tool setting program.

[0041] Step 3, setting the tool setting safety plane height H. In order to prevent the end of the industrial robot 6 from colliding with the spherical shell during the measurement process, the distance to the highest point on the surface of the spherical shell can be measured by the laser rangefinder 5 as the value of H.

[0042] Step 4. Calculate the coordinates of the tool setting points according to the number of tool setting points and the hole size of the hole to be milled. In order to set parameters in the program, the more points, the more information the surface can reflect, but efficiency issues must be taken into account. The coordinate value calculation method for each tool setting point is as follows:

[0043]

[0044] Where X i,point Y i,point Z i,point Respectively represent the coordinate values ​​of the X, Y, and Z axes of the i-th tool setting point, R hole represents the radius of the circular hole to be milled, n represents the number of tool setting points, N * Represents a positive integer. The coordinate value of the tool setting point can be calculated and input into the program.

[0045] Thus, the coordinate values ​​of eight tool setting points can be calculated (eight points are selected for efficiency), where H represents the tool setting safety distance, which can be 50 mm in this embodiment. The coordinate values ​​input into the tool setting program are calculated as follows:

[0046] First point: (250,0,H)

[0047] Second point: (176.78,176.78,H)

[0048] The third point: (0,250,H)

[0049] The fourth point: (-176.78,176.78,H)

[0050] The fifth point: (-250,0,H)

[0051] The sixth point: (-176.78,-176.78,H)

[0052] The seventh point: (0,-250,H)

[0053] The eighth point: (176.78,-176.78,H)

[0054] Step 5: Generate a tool setting program based on the tool setting point coordinates. The tool coordinate system in the tool setting program is set to the coordinate system {DMP} after the laser rangefinder is translated relative to the robot flange coordinate system. The conversion relationship is: The tool setting program also includes the workpiece coordinate system of the hole to be milled;

[0055] Step 6, run the tool setting program, record the readings of the laser rangefinder 5 at each tool setting point, calculate the minimum value of the laser rangefinder 5 readings measured on the non-uniform surface of the large spherical shell, and calculate the minimum difference Δ based on the minimum value. Δ is used as the coordinate of the first cutting position in the direction of the tool axis in the milling hole workpiece coordinate system {WP} to complete the tool setting. Subsequently, the corresponding machining program is generated based on this value.

[0056] In step 6, due to the non-uniform surface problem, the laser rangefinder 5 readings at each tool setting point on the marked circle are different. The industrial robot 6 is used to run the generated tool setting program and pause for a few seconds at each tool setting point to record the readings. The readings of the laser rangefinder 5 are recorded as a set L:

[0057] L=[L0,L1,…,L n-1 ]

[0058] The formula for calculating the minimum difference Δ under the non-uniform surface of a large spherical shell is:

[0059] Δ=-(min(L)-H-ΔZ)

[0060] The minimum value of the laser rangefinder 5 is the highest point of the non-uniform surface of the large spherical shell. The calculated Δ is the parameter of the Z-direction offset in the milling hole workpiece coordinate system {WP}, which is a negative value. Finally, the minimum difference Δ is determined to complete the tool setting.

[0061] This automated rapid tool setting method solves the problems of low precision, low efficiency, and low safety of manual tool setting, achieves reliable and efficient tool setting, and provides a guarantee for milling holes on the surface of large spherical shells.

[0062] This embodiment also includes a milling robot tool setting system for opening a hole in a large spherical shell, including a laser rangefinder 5, an industrial robot 6 and an electric spindle 4;

[0063] The laser rangefinder 5 and the electric spindle 4 are simultaneously installed on the manipulator of the industrial robot 6. The laser rangefinder 5 is used to measure the distance to the surface of the ball shell, and the milling cutter 3 is clamped on the electric spindle 4.

[0064] The control system of the industrial robot 6 is used to calculate the coordinates of the tool setting points according to the number of tool setting points set for the hole 2 to be milled, generate a tool setting program according to the tool setting point coordinates, run the tool setting program, obtain the distance to each tool setting point position on the surface of the spherical shell through the laser rangefinder 5, obtain the distance set L, calculate the minimum difference Δ=-(min(L)-H-ΔZ), Δ is used as the coordinate of the first cutting position in the tool axis direction in the milling hole workpiece coordinate system {WP}, complete the tool setting, H represents the height of the tool setting safety plane, ΔZ is the difference between the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM} in the tool axis direction.

[0065] The method for realizing the function of the control system of the industrial robot 6 is the same as the above-mentioned tool setting method.

[0066] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A milling robot tool setting system for opening holes in large spherical shells, characterized in that: The tool setting system includes a laser rangefinder, an industrial robot and an electric spindle; The laser rangefinder and the electric spindle are installed on the manipulator of the industrial robot at the same time. The laser rangefinder is used to measure the distance to the surface of the ball shell, and the milling cutter is clamped on the electric spindle. The control system of the industrial robot is used to calculate the coordinates of the tool setting points according to the number of tool setting points and the hole size of the hole to be milled, generate a tool setting program according to the tool setting point coordinates, run the tool setting program, obtain the distance to each tool setting point position on the surface of the spherical shell through a laser rangefinder, obtain a distance set L, calculate the minimum difference Δ=-(min(L)-H-ΔZ), Δ is used as the coordinate of the first cutting position in the tool axis direction in the milling hole workpiece coordinate system {WP}, complete the tool setting, H represents the height of the tool setting safety plane, ΔZ is the difference between the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM} in the tool axis direction.

2. The milling robot tool setting system for opening holes in large spherical shells according to claim 1 is characterized in that: Method for obtaining the difference ΔZ: According to the pose of the robot flange coordinate system {R6} and the tool coordinate system {TCP}, the homogeneous transformation matrix between the robot flange coordinate system {R6} and the tool coordinate system {TCP} is obtained. According to the installation position of the laser rangefinder, the homogeneous transformation matrix between the robot flange coordinate system {R6} and the laser rangefinder coordinate system {DM} is obtained Further determine the homogeneous transformation matrix between the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM} The difference ΔZ between the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM} in the tool axis direction is obtained.

3. The milling robot tool setting system for opening holes in large spherical shells according to claim 1 is characterized in that: The laser distance meter is arranged on the side of the electric spindle, and the beam direction of the laser distance meter is coaxial with the milling cutter clamped by the electric spindle.

4. The milling robot tool setting system for opening holes in large spherical shells according to claim 1 is characterized in that: H is the distance of the highest point on the surface of the spherical shell measured by a laser rangefinder.

5. The milling robot tool setting system for opening holes in large spherical shells according to claim 1 is characterized in that: Method for calculating tool point coordinates: Where X i,point Y i,point Z i,point Respectively represent the coordinate values ​​of the X, Y, and Z axes of the i-th tool setting point, R hole represents the radius of the hole to be milled, n represents the number of tool setting points, N * Represents a positive integer.

6. The milling robot tool setting system for opening holes in large spherical shells according to claim 1, characterized in that: When running the tool setting program and obtaining the distance to each tool setting point on the surface of the ball shell through the laser rangefinder, pause for a set time at each tool setting point.

7. A milling robot tool setting method for opening a large spherical shell, characterized in that: The tool setting method is implemented based on a tool setting system, which includes a laser rangefinder, an industrial robot and an electric spindle; the laser rangefinder and the electric spindle are simultaneously installed on the manipulator of the industrial robot, the laser rangefinder is used to measure the distance to the surface of the ball shell, and the milling cutter is clamped on the electric spindle; The tool setting method comprises: Determine the conversion relationship between each coordinate system, and obtain the difference ΔZ between the tool coordinate system {TCP} and the laser rangefinder coordinate system {DM} in the tool axis direction; Calculate the coordinates of the tool setting points according to the number of tool setting points and the hole size of the hole to be milled; Generate a tool setting program based on the tool setting point coordinates, run the tool setting program, obtain the distance to each tool setting point position on the surface of the spherical shell through the laser rangefinder, get the distance set L, calculate the minimum difference Δ=-(min(L)-H-ΔZ), Δ is used as the coordinate of the first cutting position in the tool axis direction in the milling hole workpiece coordinate system {WP}, and complete the tool setting. H represents the height of the tool setting safety plane.

8. A computer-readable storage device storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the tool setting method according to claim 7 are implemented.

9. A milling robot tool setting device for opening a hole in a large spherical shell, comprising a storage device, a processor, and a computer program stored in the storage device and executable on the processor, characterized in that: The processor executes the computer program to implement the steps of the tool setting method according to claim 7.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the tool setting method as claimed in claim 7 are implemented.

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