A laser tracker base station calibration physical device

Abstract

The application relates to a laser tracker base station calibration physical device in the technical field of error precision detection of numerical control machine tools and industrial robots, which comprises three parts, namely a precision rotary circular platform device, a precision ball and target mirror adjusting device and four electromagnet adjusting devices, the precision rotary circular platform device comprises a base for fixing the base station calibrator, the precision rotary circular platform is fixedly installed on the base, a stepping motor is fixedly installed on the precision rotary circular platform, and the base of the four electromagnet adjusting devices is fixedly installed on the base through screws. The application adopts a measurement positioning device based on a laser tracking principle, overcomes system error of an existing measurement technology, can accurately measure geometric error of a numerical control machining center, the device is simple, efficient, a new coordinate system is established, influence caused by self error of the numerical control machining center on measurement in a measurement process is effectively avoided, measurement precision is improved, and three-dimensional, accurate and rapid base self-calibration of the laser tracker is realized.

Description

Technical Field

[0001] This invention relates to the field of error and accuracy detection technology for CNC machine tools and industrial robots, and in particular to a physical device for calibrating a laser tracker base station. Background Technology

[0002] With the continuous development of my country's precision manufacturing industry, the accuracy of machine tool errors cannot meet current demands. Laser trackers have inherent advantages in error detection. While laser trackers offer timeliness in operation and measurement, the accuracy of base station self-calibration during measurement has consistently fallen short of requirements. The coordinates used in laser tracker measurements are machine tool reading coordinates, making it impossible to verify whether the machine tool coordinate readings are the actual position coordinates. Furthermore, the instrument's measurement methods have failed to effectively overcome the inherent errors of the CNC machining center spindle, resulting in insufficient measurement accuracy. In recent years, research on base station calibration technology by domestic and international researchers has mainly focused on the impact of base station location layout and the number of base stations on the accuracy of CNC machine tool error measurement. Currently, there is no physical calibration benchmark for laser tracker base station self-calibration. Therefore, we propose a physical device for laser tracker base station calibration. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a physical device for calibrating a laser tracker base station, which effectively avoids the impact of the inherent errors of the CNC machining center on the measurement process, improves measurement accuracy, and enables three-dimensional, accurate, and rapid self-calibration of the laser tracker base station.

[0004] The technical solution of this invention is:

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A physical device for calibrating a laser tracker base station comprises three parts: a precision rotating frustum device, a precision ball and target mirror adjustment device, and four electromagnet adjustment devices.

[0007] In a further technical solution, the precision rotating frustum device includes a base for fixing the base station calibrator, a precision rotating frustum fixedly mounted on the base, a stepper motor fixedly mounted on the precision rotating frustum, and four electromagnet adjustment device bases fixedly mounted on the base by screws.

[0008] In a further technical solution, the precision ball and target mirror adjustment device includes a precision ball and target mirror fixing seat connected to a precision rotating frustum. The precision ball and target mirror fixing seat is equipped with two upper and lower cylindrical guide rails, and guide rail sliders are respectively installed on the two cylindrical guide rails. The guide rail sliders are connected to the precision ball and target mirror adjustment plate. Compression spring one and compression spring two are installed on both sides to keep the guide rail sliders in a balanced state. The precision ball mounting plate is installed inside the precision ball and target mirror adjustment plate. It is prevented from falling out by positioning blocks installed on the precision ball and target mirror adjustment plate. Y-axis balance spring and Z-axis balance spring are installed inside the precision ball and target mirror adjustment plate to keep the precision ball mounting plate in a balanced state. The precision ball is fixedly installed on the precision ball mounting plate. The target mirror fixing seat is also fixedly installed on the precision ball mounting plate. The target mirror is installed on the target mirror fixing seat.

[0009] In a further technical solution, the four electromagnet adjustment devices include electromagnet adjustment device one, electromagnet adjustment device two, electromagnet adjustment device three, and electromagnet adjustment device four, which are respectively mounted on the base. The four electromagnet adjustment devices are evenly distributed around the precision rotating frustum. Electromagnet adjustment device one includes three electromagnets with non-magnetic ball sockets, which are mounted on electromagnet base one. Electromagnet base one is mounted on electromagnet adjustment slider one. Electromagnet adjustment slider one is mounted on electromagnet adjustment support plate one and electromagnet adjustment fixing plate one. Electromagnet adjustment support plate one is mounted on electromagnet adjustment fixing plate one. Electromagnet adjustment device one is mounted on the base through the electromagnet adjustment device base.

[0010] In a further technical solution, the electromagnet adjustment device 2 includes three electromagnets 2 with non-magnetic ball sockets, which are mounted on the electromagnet base 2. The electromagnet base 2 is mounted on the electromagnet adjustment slider 2. The electromagnet adjustment slider 2 is mounted on the electromagnet adjustment support plate 2 and the electromagnet adjustment fixing plate 2. The electromagnet adjustment support plate 2 is mounted on the electromagnet adjustment fixing plate 2. The electromagnet adjustment device 2 is mounted on the base through the electromagnet adjustment base.

[0011] In a further technical solution, the electromagnet adjustment device three includes three electromagnets three with non-magnetic ball sockets, which are mounted on the electromagnet base three. The electromagnet base three is mounted on the electromagnet adjustment slider three. The electromagnet adjustment slider three is mounted on the electromagnet adjustment support plate three and the electromagnet adjustment fixing plate three. The electromagnet adjustment support plate three is mounted on the electromagnet adjustment fixing plate three. The electromagnet adjustment device three is mounted on the base through the electromagnet adjustment base three.

[0012] In a further technical solution, the electromagnet adjustment device four includes three electromagnets four with non-magnetic ball sockets, which are mounted on the electromagnet base four. The electromagnet base four is mounted on the electromagnet adjustment slider four. The electromagnet adjustment slider four is mounted on the electromagnet adjustment support plate four and the electromagnet adjustment fixing plate four. The electromagnet adjustment support plate four is mounted on the electromagnet adjustment fixing plate four. The electromagnet adjustment device four is mounted on the base through the electromagnet adjustment base four.

[0013] The beneficial effects of this invention are:

[0014] This invention employs a measurement and positioning device based on the principle of laser tracking, which overcomes the systematic errors of existing measurement technologies and can accurately measure the geometric errors of CNC machining centers. The device is simple and efficient to operate, establishes a new coordinate system, and effectively avoids the influence of the inherent errors of the CNC machining center on the measurement process, thereby improving measurement accuracy and realizing three-dimensional, accurate, and rapid self-calibration of the laser tracker base station. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of the structure of the precision ball and target mirror adjustment device according to an embodiment of the present invention;

[0017] Figure 3 This is a schematic diagram of the structure of the precision ball and target mirror adjustment device according to an embodiment of the present invention;

[0018] Figure 4 This is a schematic diagram of the structure of the electromagnet adjustment device according to an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures:

[0020] 1. Base; 2. Electromagnet adjustment device base; 3. Electromagnet adjustment support plate one; 4. Electromagnet adjustment slider one; 5. Electromagnet base one; 6. Electromagnet one; 7. Precision ball and target lens fixing seat; 8. Target lens fixing seat; 9. Target lens; 10. Electromagnet base two; 11. Electromagnet two; 12. Electromagnet adjustment slider two; 13. Electromagnet adjustment support plate two; 14. Electromagnet adjustment fixing plate two; 15. Electromagnet three; 16. Electromagnet base three; 17. Electromagnet adjustment slider three; 18. Electromagnet adjustment support plate three; 19. Electromagnet adjustment fixing plate three; 20. Electromagnet... 21. Precision rotating frustum; 22. Electromagnet; 23. Electromagnet base; 24. Electromagnet adjusting slider; 25. Electromagnet adjusting support plate; 26. Electromagnet adjusting base; 27. Electromagnet adjusting support plate; 28. Cylindrical guide rail; 29. ​​Precision ball and target mirror adjusting plate; 30. Precision ball; 31. Positioning block; 32. Y-axis balance spring; 33. Z-axis balance spring; 34. Precision ball mounting plate; 35. Compression spring; 36. Compression spring; 37. Guide rail slider; 38. Stepper motor; 39. Electromagnet adjusting fixing plate. Detailed Implementation

[0021] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0022] Example:

[0023] Reference Figure 1 , Figure 4A physical device for calibrating a laser tracker base station includes a precision rotating frustum. During assembly, the precision rotating frustum 21 and four identical electromagnet adjustment bases 2 are fixedly mounted on a base 1 using screws. Electromagnet adjustment devices one, two, three, and four are fixedly mounted on the base 1 via their respective bases 2. None of the four electromagnet adjustment devices are located around the precision rotating frustum 21. Electromagnet adjustment device one includes three electromagnets 6 with non-magnetic ball sockets, which are mounted on an electromagnet base 5. The electromagnet base 5 is mounted on an electromagnet adjustment slider 4. The electromagnet adjustment slider 4 has grooves designed on it, allowing the electromagnets 6 with non-magnetic ball sockets to make minute adjustments through these grooves. The electromagnet adjustment slider 4 is mounted on the electromagnet adjustment support plate 3 and the electromagnet adjustment fixing plate 39. The electromagnet adjustment support plate 3 is fixedly mounted on the electromagnet adjustment fixing plate 39. Grooves are designed on the electromagnet adjustment support plate 3 and the electromagnet adjustment fixing plate 39 respectively. The electromagnet 6 with a non-magnetic ball socket can move slightly within the grooves of the electromagnet adjustment support plate 3 and the electromagnet adjustment fixing plate 39 through the electromagnet adjustment slider 4. The electromagnet 6 with a non-magnetic ball socket is fixed in the corresponding position by screws. The electromagnet adjustment device 1 is mounted on the base 1 through the electromagnet adjustment device base 2. The assembly principle of the electromagnet adjustment device 2, electromagnet adjustment device 3, and electromagnet adjustment device 4 is the same as that of the electromagnet adjustment device 1, and will not be described in detail here.

[0024] Reference Figure 1 , Figure 2 and Figure 3During assembly, the precision ball and target mirror adjustment device is assembled by fixing the precision ball and target mirror mounting base 7 to the precision rotating frustum 21 with screws. The base is mounted on a mounting hole in one direction of the electromagnet adjustment device. The precision ball and target mirror mounting base 7 has two cylindrical guide rails 28, each with a guide rail slider 37. The guide rail slider 37 engages with the precision ball and target mirror adjustment plate 29. Compression springs 35 and 36 are installed on both sides of the guide rail slider 37 to maintain its balance. The precision ball mounting plate 34 is installed inside the precision ball and target mirror adjustment plate 29 and is prevented from falling out by positioning blocks 31 installed on the plate. A Y-axis balance spring is installed inside the precision ball and target mirror adjustment plate 29. The Z-axis balance spring 32 and Z-axis balance spring 33 keep the precision ball mounting plate 34 in a balanced state. The precision ball 30 is fixedly mounted on the precision ball mounting plate 34. The target mirror mounting base 8 is also fixedly mounted on the precision ball mounting plate 34. The target mirror 9 is mounted on the target mirror mounting base 8. That is, the relative position of the target mirror 9 and the precision ball 30 is in an absolutely fixed state. When a pulling force is applied to the precision ball 30, the balance state of the compression spring 1 35 and compression spring 2 36, as well as the Y-axis balance spring 32 and Z-axis balance spring 33, will be broken. The precision ball 30 and the target mirror 9 will make a slight movement, which will cooperate with the electromagnet 1 6 with a non-magnetic ball socket on the electromagnet adjustment device 1. When this external force is removed, the precision ball 30 and the target mirror 9 return to their original positions and maintain a balanced state.

[0025] Reference Figure 1 , Figure 2 , Figure 3 and Figure 4 Introducing how to use this device:

[0026] After assembling the device, connect it to the spindle of the CNC machining center via the spindle connection device 40, and fix it to the CNC machining center worktable with bolts. Next, measure the reference points. First, the precision ball and target mirror mounting base 7 are fixedly connected to the precision rotary frustum 21 with screws and installed in the mounting hole on one side of the electromagnet adjustment device. At this time, the precision ball 30 and the electromagnet 6 with a non-magnetic ball socket on the first magnet adjustment device are roughly in the same position. When the electromagnet 6 with the non-magnetic ball socket is energized, it gains magnetic force. This magnetic force breaks the balance between the precision ball mounting plate 34 and the target mirror mounting base 8. The precision ball 30 and the electromagnet 6 with the non-magnetic ball socket cooperate to adjust the electromagnet with the non-magnetic ball socket. The precision ball 30 is moved slightly within the grooves on the electromagnet adjusting slider 4, the electromagnet adjusting support plate 3, and the electromagnet adjusting fixing plate 39, so that the precision ball 30 and the electromagnet 6 with the non-magnetic ball socket are fully engaged. The position of the electromagnet 6 with the non-magnetic ball socket is fixed by screws. At this time, the position of the electromagnet 6 with the non-magnetic ball socket is determined, that is, the first spatial position of the target mirror 9 in the device is determined. Then, the electromagnet 6 with the non-magnetic ball socket is de-energized, the electromagnet 6 with the non-magnetic ball socket loses its magnetic force, and the precision ball 30 and the target mirror 9 return to their original positions and maintain a balanced state.

[0027] Start the stepper motor 38 to drive the precision rotating frustum 21 to rotate. Rotate the precision rotating frustum 21 by 90°, causing the precision ball and target mirror fixing seat 7 to rotate to the second electromagnet adjustment device. Repeat the adjustment steps of the first electromagnet adjustment device to make the precision ball 30 fully cooperate with the second electromagnet 11 with the non-magnetic ball socket. Fix the position of the second electromagnet 11 with the non-magnetic ball socket with screws. At this time, the position of the second electromagnet 11 with the non-magnetic ball socket is determined, that is, the second spatial position of the target mirror 9 in the device is determined. Then, de-energize the second electromagnet 11 with the non-magnetic ball socket. The second electromagnet 11 with the non-magnetic ball socket loses its magnetic force, and the precision ball 30 and the target mirror 9 return to their original positions and maintain a balanced state.

[0028] Start the stepper motor 38 to drive the precision rotating table 21 to rotate. Rotate the precision rotating table 21 by 90°, causing the precision ball and target mirror fixing seat 7 to rotate to the third position of the electromagnet adjustment device. Repeat the adjustment steps of the first position of the electromagnet adjustment device to make the precision ball 30 fully cooperate with the electromagnet 3 15 with the non-magnetic ball socket. Fix the position of the electromagnet 3 15 with the non-magnetic ball socket with screws. At this time, the position of the electromagnet 3 15 with the non-magnetic ball socket is determined, that is, the third spatial position of the target mirror 9 in the device is determined. Then, de-energize the electromagnet 3 15 with the non-magnetic ball socket. The electromagnet 3 15 with the non-magnetic ball socket loses its magnetic force, and the precision ball 30 and the target mirror 9 return to their original positions and maintain a balanced state.

[0029] Start the stepper motor 38 to drive the precision rotating frustum 21 to rotate. Rotate the precision rotating frustum 21 by 90°, causing the precision ball and target mirror fixing seat 7 to rotate to the fourth position of the electromagnet adjustment device. Repeat the adjustment steps at the first position of the electromagnet adjustment device to make the precision ball 30 fully cooperate with the electromagnet 4 22 with the non-magnetic ball socket. Fix the position of the electromagnet 4 22 with the non-magnetic ball socket with screws. At this time, the position of the electromagnet 4 22 with the non-magnetic ball socket is determined, that is, the fourth spatial position of the target mirror 9 in the device is determined. Then, de-energize the electromagnet 4 22 with the non-magnetic ball socket. The electromagnet 4 22 with the non-magnetic ball socket loses its magnetic force, and the precision ball 30 and the target mirror 9 return to their original positions and maintain a balanced state.

[0030] Start the stepper motor 38 to drive the precision rotary table 21 to rotate, rotate the precision rotary table 21 90°, and return it to the initial position;

[0031] After completing the above steps, the positions of the four electromagnet adjustment devices are determined, that is, the four spatial positions T1, T2, T3, and T4 of the target mirror within the device are determined. The spatial coordinates of the four target mirror positions in the base station calibration device are calibrated using a high-precision coordinate measuring machine, and then the spatial position of the target mirror within the base station calibration device is derived.

[0032] After completing the geometric parameter calibration process, the laser tracker base station is calibrated. The electromagnet 6 with a non-magnetic ball socket is energized, and it acquires magnetic force. The precision ball 30 and the electromagnet 6 are fully engaged. At this point, the position of the target mirror 9 is determined. The distance measurement reading at this position is recorded using the laser tracker and denoted as l. 1. At this point, the target mirror 9 is at coordinates p1(x1, y1, z1). When the electromagnet 6 with the non-magnetic ball socket is de-energized, it loses its magnetic force, and the precision ball 30 and the target mirror 9 return to their original positions and maintain balance. Then, the stepper motor 38 is started, driving the precision rotating frustum 21 to rotate. Rotating the precision rotating frustum 21 by 90° causes the precision ball and the target mirror mounting base 7 to rotate to the electromagnet adjustment device 2. The electromagnet 11 with the non-magnetic ball socket is then energized, gaining magnetic force. The precision ball 30 and the electromagnet 11 with the non-magnetic ball socket are now perfectly matched. At this point, the position of the target mirror 9 is determined, and the distance is measured using a laser tracker and recorded as l2. The coordinates are p2(x2, y2, z2). The electromagnet 11 with the non-magnetic ball socket is de-energized, and the electromagnet 11 with the non-magnetic ball socket loses its magnetic force. The precision ball 30 and the target mirror 9 return to their original positions and maintain a balanced state. The stepper motor 38 is started, driving the precision rotating frustum 21 to rotate. The precision rotating frustum 21 is rotated 90°, driving the precision ball and the target mirror fixing seat 7 to rotate to the electromagnet adjustment device 3. The electromagnet 15 with the non-magnetic ball socket is energized, and the electromagnet 15 with the non-magnetic ball socket obtains... Magnetic force is applied, and the precision ball 30 and the electromagnet 315 with a non-magnetic ball socket are fully engaged. At this time, the position of the target mirror 9 is determined, and the distance is measured by a laser tracker and recorded as l3, with coordinates p3(x3, y3, z3). The electromagnet 315 with a non-magnetic ball socket is de-energized, and the electromagnet 315 with a non-magnetic ball socket loses its magnetic force. The precision ball 30 and the target mirror 9 return to their original positions and maintain a balanced state. The stepper motor 38 is started, driving the precision rotating platform 21 to rotate. The precision rotating platform 21 is rotated 90°, driving the precision ball and the target mirror fixing seat 7 to rotate to the four positions of the electromagnet adjustment device, and the non-magnetic ball socket is then moved to the four positions of the electromagnet adjustment device. When electromagnet 422 is energized, the electromagnet 422 with non-magnetic ball sockets acquires magnetic force, and precision ball 30 is fully engaged with electromagnet 422 with non-magnetic ball sockets. At this time, the position of target mirror 9 is determined, and the distance is measured by laser tracker and recorded as l4, coordinate p4(x4, y4, z4). When electromagnet 422 with non-magnetic ball sockets is de-energized, electromagnet 422 with non-magnetic ball sockets loses magnetic force, and precision ball 30 and target mirror 9 return to their original positions and maintain a balanced state. Stepper motor 38 is started to drive precision rotating frustum 21 to rotate, and precision rotating frustum 21 is rotated 90° to return to the initial position.

[0033] After measuring the distance readings between the laser tracker and the four target mirrors, as well as the coordinates of the four target mirror positions, data analysis was performed. This involved utilizing the GPS positioning principle and the distance formula between two points. A set of ternary high-order nonlinear redundant equations can be derived:

[0034]

[0035] Solving the above equation, we can find p(x, y, z).

[0036] In summary, the laser tracker base station calibration device of the present invention has good positioning accuracy, can effectively eliminate the errors inherent in the CNC machining center itself, better complete the measurement of the positioning error of the CNC machining center, and achieve high-precision, fast and effective measurement.

[0037] The above embodiments merely illustrate specific implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A physical device for calibrating a laser tracker base station, comprising three parts: a precision rotating frustum device, a precision sphere and target mirror adjustment device, and four electromagnet adjustment devices; characterized in that: The precision rotating frustum device includes a base fixedly mounted on a machining center, a precision rotating frustum fixedly mounted on the base, a stepper motor fixedly mounted on the precision rotating frustum, and four identical electromagnet adjustment device bases fixedly mounted on the base. The precision ball and target mirror adjustment device of the physical device includes a precision ball and target mirror fixing base connected to a precision rotating frustum. The precision ball and target mirror fixing base is equipped with two upper and lower cylindrical guide rails. Guide rail sliders are respectively installed on the two cylindrical guide rails. A precision ball and target mirror adjustment plate is connected to the guide rail sliders. Compression spring one and compression spring two are respectively installed on both sides of the guide rail slider at its top. A precision ball mounting plate is installed inside the precision ball and target mirror adjustment plate. A positioning block is also installed on the precision ball and target mirror adjustment plate. A Y-axis balance spring and a Z-axis balance spring are respectively installed inside the precision ball and target mirror adjustment plate. A precision ball is fixedly installed on the precision ball mounting plate. A target mirror fixing base is also fixedly installed on the precision ball mounting plate. A target mirror is installed on the target mirror fixing base. The physical device includes four electromagnet adjustment devices: Electromagnet Adjustment Device 1, Electromagnet Adjustment Device 2, Electromagnet Adjustment Device 3, and Electromagnet Adjustment Device 4, which are respectively mounted on the base. The four electromagnet adjustment devices are evenly distributed around the precision rotating frustum. Electromagnet Adjustment Device 1 includes three electromagnets with non-magnetic ball sockets. An electromagnet base is mounted on one side of the electromagnet. An electromagnet adjustment slider is mounted on the bottom of the electromagnet base. An electromagnet adjustment support plate and an electromagnet adjustment fixing plate are mounted on the bottom of the electromagnet adjustment slider. The electromagnet adjustment support plate is mounted on the electromagnet adjustment fixing plate. The electromagnet adjustment device is mounted on the base via the electromagnet adjustment base.

2. The physical device for calibrating a laser tracker base station according to claim 1, characterized in that: The electromagnet adjustment device two includes three electromagnets two with non-magnetic ball sockets, an electromagnet base two is installed at the bottom of the electromagnet two, and an electromagnet adjustment slider two is installed at the bottom of the electromagnet base two. The bottom end of the electromagnet adjusting slider two is equipped with an electromagnet adjusting support plate two and an electromagnet adjusting fixing plate two. The electromagnet adjusting support plate two is mounted on the electromagnet adjusting fixing plate two, and the electromagnet adjusting device two is mounted on the base through an electromagnet adjusting base.

3. The physical device for calibrating a laser tracker base station according to claim 1, characterized in that: The electromagnet adjustment device 3 includes three electromagnets 3 with non-magnetic ball sockets 3. An electromagnet base 3 is installed at the bottom end of the electromagnet 3. An electromagnet adjustment slider 3 is installed at the bottom end of the electromagnet base 3. An electromagnet adjustment support plate 3 and an electromagnet adjustment fixing plate 3 are installed at the bottom end of the electromagnet adjustment slider 3. The electromagnet adjustment support plate 3 is installed on the electromagnet adjustment fixing plate 3. The electromagnet adjustment device 3 is installed on the base through the electromagnet adjustment base 3.

4. The physical device for calibrating a laser tracker base station according to claim 1, characterized in that: The electromagnet adjustment device 4 includes three electromagnets 4 with non-magnetic ball sockets 4. An electromagnet base 4 is installed at the bottom end of the electromagnet 4. An electromagnet adjustment slider 4 is installed at the bottom end of the electromagnet base 4. An electromagnet adjustment support plate 4 and an electromagnet adjustment fixing plate are installed at the bottom end of the electromagnet adjustment slider 4. The electromagnet adjustment support plate 4 is installed on the electromagnet adjustment fixing plate. The electromagnet adjustment device 4 is installed on the base through the electromagnet adjustment base 4.

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