Laser tracker target ball assembling tool and method
阅读说明：本技术 激光跟踪仪靶球装配工装及靶球装配方法 (Laser tracker target ball assembling tool and method ) 是由 郑剑和 于 2019-09-20 设计创作，主要内容包括：本发明提供了一种激光跟踪仪靶球装配工装及靶球装配方法,靶球装配工装包含上模和下模,下模中设有用于安装钢球机体和回射器的定位块,在定位块的一侧安装有横向定位仪,在下模上固定有导柱,上模安装在导柱上且上模可沿导柱上下移动,上模上设有用于对靶球进行定位的定位面,在上模上设有同样位于工装中心的纵向定位仪；装配方法步骤如下：涂胶、钢球基体定位、放置光学器件、胶合、保护环安装、光学中心精度检测。本发明能够进一步提高回射器与钢球机体的定位精度,尽可能地减少胶合装配误差,以此来减少靶球光学中心误差,光学器件与球体的安装采用独有的快速和批量高精度的装配方式,使得装配的效率大大提高,从而降低生产的成本。(The invention provides a laser tracker target ball assembly tool and a target ball assembly method, wherein the target ball assembly tool comprises an upper die and a lower die, a positioning block for mounting a steel ball machine body and a retroreflector is arranged in the lower die, a transverse position finder is arranged on one side of the positioning block, a guide pillar is fixed on the lower die, the upper die is mounted on the guide pillar, the upper die can move up and down along the guide pillar, a positioning surface for positioning a target ball is arranged on the upper die, and a longitudinal position finder which is also positioned in the center of the tool is arranged on the upper die; the assembling method comprises the following steps: gluing, positioning a steel ball substrate, placing an optical device, gluing, installing a protection ring and detecting the precision of an optical center. The invention can further improve the positioning precision of the retroreflector and the steel ball body, reduce the gluing assembly error as much as possible, reduce the optical center error of the target ball, and greatly improve the assembly efficiency by adopting a unique rapid and batch high-precision assembly mode for the installation of the optical device and the ball body, thereby reducing the production cost.)
1. The utility model provides a laser tracker target ball assembly fixture which characterized in that: the target ball assembling tool comprises an upper die and a lower die, wherein a positioning block which is located at the center of the tool and used for installing a steel ball machine body and a retroreflector is arranged in the lower die, a transverse position indicator is installed on one side of the positioning block, a guide pillar is fixed on the lower die, the upper die is installed on the guide pillar, the upper die can move up and down along the guide pillar, a positioning surface used for positioning a target ball is arranged on the upper die, and a longitudinal position indicator which is also located at the center of the tool is arranged on the upper die.
2. The laser tracker target ball assembly fixture of claim 1, characterized in that: the upper die is provided with a guide sleeve, and the upper die is arranged on the guide pillar through the guide sleeve.
3. The laser tracker target ball assembly fixture of claim 1, characterized in that: the positioning surface is an arc surface matched with the surface of the target ball.
4. The laser tracker target ball assembly fixture of claim 3, characterized in that: the arc center of the positioning surface is superposed with the center lines of the positioning block and the longitudinal positioning instrument.
5. A laser tracker target ball assembling method is characterized in that: the method comprises the following steps:
gluing, namely adopting epoxy resin glue, and mixing a curing agent A and an adhesive B according to the proportion of 1: 1, using quantitative glue to mix fully and uniformly, and injecting the mixture into the bottom of the cavity of the steel ball matrix;
positioning a steel ball matrix, and placing the steel ball matrix subjected to glue injection into an upper die for preliminary positioning;
placing an optical device, placing the optical device on a lower die, and performing primary positioning;
gluing, closing the lower die and the upper die, and performing precise positioning and fixing;
mounting a protection ring, opening the upper die and the lower die after the glue is dried, taking out the target ball, and mounting the protection ring;
optical center precision detection, namely performing optical center precision detection on the mounted target ball;
and (3) vibration, falling and antifouling decontamination tests are carried out, and the vibration, falling and antifouling decontamination tests are carried out on the target ball after the target ball is installed.
6. The method of assembling a laser tracker target ball of claim 5, wherein: in the gluing step, the glue is epoxy resin glue.
7. The method of assembling a laser tracker target ball of claim 5, wherein: in the optical center precision detection, a rotation test, a swing test and a tracking distance detection are also required to be performed on the target ball.
8. The laser tracker target ball assembly method of claim 7, wherein said rotation test comprises the steps of: the target ball is placed on the reference magnetic base opposite to the laser beam, the tracker is switched to an interferometer mode, the target ball rotates 8 angles around the laser beam, space coordinates of 8 position points are recorded, and the maximum discrete radius of the 8 position points is calculated and is the transverse error of the optical center of the target ball.
9. The laser tracker target ball assembly method of claim 7, wherein the step of the wobble test is as follows: the target ball swings for about 20 degrees around the laser beam in four directions, namely up, down, left and right directions, the space coordinates of position points in the four directions are recorded, and the maximum discrete radius of 4 position points is calculated, so that the longitudinal error of the optical center of the target ball can be approximately obtained; care was taken not to touch the guard ring against the laser beam when the oscillation was at the limit, so as not to obtain a possible erroneous reading.
Technical Field
The invention relates to the technical field of artificial planting, in particular to a laser tracker target ball assembling tool and a target ball assembling method.
Background
The Laser Tracker (Laser Tracker) is a high-precision large-space three-dimensional measuring instrument, integrates advanced technologies such as a Laser ranging technology, a photoelectric detection technology, a precision mechanical technology, a computer and control technology, a modern numerical calculation theory and the like, tracks a space moving target (target ball) and measures a space three-dimensional coordinate of the target in real time. Generally, the system comprises a high-precision laser ranging module (an ADM absolute ranging module or an additional IFM laser interferometer), an azimuth grating encoder and a servo motor thereof, a pitch grating encoder and a servo motor thereof, a position sensing tracking module, a precision level meter, a meteorological station and the like. The method has the characteristics of high precision, high efficiency, real-time tracking measurement, quick installation, simple and convenient operation and the like, and is widely applied to three-dimensional industrial measurement of large-size objects such as aerospace ship heavy industry wind power automobile machinery and the like.
Target ball, SMR (SMR), also known as spherical hollow retroreflector, the core component is a cube corner retroreflector consisting of three high-precision mutually perpendicular optical reflecting surfaces, which is formed by gluing three pieces of glass (or machined by aluminum columns), the retroreflector is glued on a perforated high-precision stainless steel ball, reflects the beam of a laser tracker, provides the target for a laser tracking and ranging system, is similar to a three-coordinate spherical probe, and requires that the optical center of the retroreflector and the center of the steel ball be as coincident as possible in order to reduce the measurement error caused by the target ball, there is another form of target ball, the optical hollow cube corner is directly machined on the steel ball, and is made into three mutually perpendicular mirror surfaces, the mirror surfaces are generally plated with films (gold, silver or aluminum) because there is no inlay (glass or aluminum) as the reflective surface, the target ball can withstand some degree of impact (so as not to damage the surface of the ball).
According to the currently used technology, a high-precision steel ball is generally machined by stainless steel to form a ball body with a cavity, due to the limitation of the machinability of the steel ball in the prior art, the machinability of the steel ball limits the surface hardness of the steel ball to be not too high, the roundness can be adversely affected after the cavity machining, the surface of the steel ball needs to be subjected to a large number of frequent contact measurements with a workpiece, the steel ball is easy to wear and cause error increase, and therefore the steel ball is easy to scrap, and the outer surface needs to be re-machined to recover the due precision of the steel ball.
Disclosure of Invention
The invention aims to provide a laser tracker target ball assembling tool and a laser tracker target ball assembling method, which are used for solving the problems that the target ball is high in assembling difficulty and poor in assembling precision, an optical device is easy to displace and degum, the precision is insufficient and the like.
The invention provides a laser tracker target ball assembly tool which comprises an upper die and a lower die, wherein a positioning block which is positioned in the center of the tool and used for mounting a steel ball machine body and a retroreflector is arranged in the lower die, a transverse position finder is arranged on one side of the positioning block, a guide pillar is fixed on the lower die, the upper die is arranged on the guide pillar, the upper die can move up and down along the guide pillar, a positioning surface used for positioning a target ball is arranged on the upper die, and a longitudinal position finder which is also positioned in the center of the tool is arranged on the upper die.
Further, the upper die is provided with a guide sleeve, and the upper die is arranged on the guide pillar through the guide sleeve.
Furthermore, the positioning surface is an arc surface matched with the surface of the target ball.
Furthermore, the arc center of the positioning surface is superposed with the center lines of the positioning block and the longitudinal positioning instrument.
The invention also provides a laser tracker target ball assembling method, which comprises the following steps:
gluing, namely adopting epoxy resin glue, and mixing a curing agent A and an adhesive B according to the proportion of 1: 1, using quantitative glue to mix fully and uniformly, and injecting the mixture into the bottom of the cavity of the steel ball matrix;
positioning a steel ball matrix, and placing the steel ball matrix subjected to glue injection into an upper die for preliminary positioning;
placing an optical device, placing the optical device on a lower die, and performing primary positioning;
gluing, closing the lower die and the upper die, and performing precise positioning and fixing;
mounting a protection ring, opening the upper die and the lower die after the glue is dried, taking out the target ball, and mounting the protection ring;
and (4) optical center precision detection, namely performing optical center precision detection on the mounted target ball.
Further, in the gluing step, the glue is epoxy resin glue.
Furthermore, in the optical center accuracy detection, a rotation test, a swing test and a tracking distance detection are required to be performed on the target ball.
Further, the steps of the rotation test are as follows: the target ball is placed on the reference magnetic base opposite to the laser beam, the tracker is switched to an interferometer mode, the target ball rotates 8 angles around the laser beam, space coordinates of 8 position points are recorded, and the maximum discrete radius of the 8 position points is calculated and is the transverse error of the optical center of the target ball.
Further, the step of the swing test is as follows: the target ball swings for about 20 degrees around the laser beam in four directions, namely up, down, left and right directions, the space coordinates of position points in the four directions are recorded, and the maximum discrete radius of 4 position points is calculated, so that the longitudinal error of the optical center of the target ball can be approximately obtained; care was taken not to touch the guard ring against the laser beam when the oscillation was at the limit, so as not to obtain a possible erroneous reading.
The technical scheme of the invention has the beneficial effects that: the assembly tool is used, the target ball assembly method is applied to the assembly tool, the positioning accuracy of the retroreflector and the steel ball body is further improved, the gluing assembly error is reduced as much as possible, the optical center error of the target ball is reduced, and the optical device and the ball body are installed in a unique rapid and batch high-accuracy assembly mode, so that the assembly efficiency is greatly improved, and the production cost is reduced.
Drawings
FIG. 1 is a schematic structural diagram according to a first embodiment of the present invention;
FIG. 2 is a schematic view of an embodiment of the present invention with a target ball attached;
FIG. 3 is a Zygo interferogram.
In the figure:
1-upper mould; 2-lower mould; 3-positioning a block; 4-a transverse positioning instrument; 5-guide pillar; 6-positioning surface; 7-guide sleeve; 8-steel ball machine body; 9-a retroreflector; 10-longitudinal positioning instrument.
Detailed Description
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention.
As shown in fig. 1, an embodiment of the present invention provides a laser tracker target ball assembly fixture, which includes an
The embodiment of the invention discloses an assembly method of a laser tracker target ball, which aims to ensure the installation precision to the maximum extent and avoid the interference of uncertain factors of the environment, and the installation environment requirements of optical devices are as follows: 1. no dust; 2. keeping the temperature at 20 ℃ plus or minus 2 ℃; 3. no vibration exists; 4. all parts entering the installation must be guaranteed to be clean and dustless.
The assembly method of the laser tracker target ball comprises the following process steps:
s01, gluing, namely, adopting epoxy resin glue, and mixing the curing agent A and the adhesive B according to the proportion of 1: 1, using quantitative glue to mix fully and uniformly, and injecting the mixture into the bottom of the cavity of the steel ball matrix;
s02: positioning a steel ball matrix, and placing the steel ball matrix subjected to glue injection into an upper die for preliminary positioning;
s03: placing an optical device, placing the optical device on a lower die, and performing primary positioning;
s04: gluing, closing the lower die and the upper die, and performing precise positioning and fixing;
s05: mounting a protection ring, opening the upper die and the lower die after the glue is dried, taking out the target ball, and mounting the protection ring;
s06: optical center precision detection, namely performing optical center precision detection on the mounted target ball;
s07: and (3) vibration, falling and antifouling decontamination tests are carried out, and the vibration, falling and antifouling decontamination tests are carried out on the target ball after the target ball is installed.
In S01, in order to meet the requirements of long-term dimensional stability, peeling strength, vibration prevention and temperature resistance of the optical cube corner retroreflector and the steel ball matrix, after a plurality of tests, the embodiment of the invention adopts a specially prepared epoxy resin glue, and the target ball using the glue still maintains the expected stability performance after 13 months after the glue is cured.
The invention relates to a device and a method for detecting the precision of an optical center, which utilize a customized micrometer and a microscope to test and verify the transverse error and the longitudinal error of a target ball, and in order to consider the convenience of a user for verifying the precision of the target ball center, the scheme also utilizes a zero point of a laser tracker or a magnetic base reference point on a heavy tripod to test and verify. Firstly, ensuring the cleanness, completeness and stability of the magnetic seat; 2. the static repeatability error of the laser tracker is less than 5 microns for at least 5 minutes; otherwise the test results may lose their referential meaning.
And (3) rotation test: the target ball is placed on the reference magnetic base opposite to the laser beam, the tracker is switched to an interferometer mode (if an IFM module is available), the target ball rotates for 8 angles around the laser beam, space coordinates of 8 position points are recorded, and the maximum discrete radius of the 8 position points is calculated and is the transverse error of the optical center of the target ball;
swing test: the target ball swings for about 20 degrees around the laser beam in four directions, namely up, down, left and right directions, the space coordinates of position points in the four directions are recorded, and the maximum discrete radius of 4 position points is calculated, so that the longitudinal error of the optical center of the target ball can be approximately obtained; care was taken not to touch the guard ring against the laser beam when the oscillation was at the limit, so as not to obtain a possible erroneous reading.
And (4) tracking distance detection, wherein the tracking distance of a new target ball is over 40 meters in general. When necessary, the light intensity attenuation value of infrared laser (ADM) of the laser tracker needs to be adjusted, so that the returned laser light intensity reaches a set value of 0.7. Too high (greater than 0.9) or too low (less than 0.1) of return light intensity will render the laser tracker range reading invalid and inoperable, and the settings may vary from manufacturer to manufacturer. This item is a spot check.
The optical center error test results are shown in table 1, in addition, the test of other parameters is shown in fig. 3, fig. 3 is a Zygo interferogram, a Zygo interferometer is adopted to measure multiple indexes of the laser tracker target ball to obtain the result of fig. 3, and the result has detection results such as dihedral angle error, comprehensive angle error, central wavefront distortion and the like, which shows that the laser tracker target ball produced by using the target ball tool and the target ball assembling method in the embodiment of the invention meets various test requirements.
Serial number
Mirror type
Numbering
Optical center error/
1
SMR1.5in
JHM6007
0.005
2
SMR0.5in
JHM8027
0.003
TABLE 1
The following description of experimental parameter terms related to target spheres:
dihedral Angle error (Dihedral-Angle error): on the three reflecting surfaces of an ideal cube corner, the angle between two adjacent mirror surfaces is exactly 90 degrees. Whereas the actual cube corner reflecting surfaces always differ from each other by 90 degrees from the theoretical angle, the difference is typically measured in arc seconds. This difference is called dihedral angle error.
Maximum laser integrated angle error (Max Beam development): theoretically, a laser beam should be coaxial with the incident beam and form 180 degrees after being reflected back through the target sphere. Due to the manufacturing error of the retroreflector, the actually reflected light beam always has an error of several arc seconds with the incident light beam, and the errors of the incident light beam and the incident light beam are different, wherein the error of the maximum laser reflection angle is called as the maximum laser synthetic angle error.
Central wavefront distortion: including effects due to flatness of the panel and dihedral angle errors, both of which affect the wavefront of the laser beam returning from the reflector. Since the laser beam reflected by the laser tracker requires the return path, in the reflection area of the target ball, the area with the diameter of about 7mm near the central point is the most concentrated place of the laser beam energy, and the wave front distortion value is the key.
Polarization error: laser light reflected back into the laser, whether inside an Interferometer (IFM) or an Absolute Distance Meter (ADM), may be sensitive to polarization. If the laser tracker is sensitive to polarization, the reflective properties of the mirror coating of the target sphere become important. The target ball therefore requires a relevant quantitative test to know the polarization properties of the produced target ball.
Optical center error: the optical center error is one of the key indicators of the quality of target ball manufacture. It can be decomposed into lateral and longitudinal errors. The lateral error refers to the radius between the orbit circle of the optical reflection center and the target ball rotation center (sphere center point) after the target ball rotates around the axis of the opening circle for a circle at the fixed magnetic base. Longitudinal error, the deviation of the reflection center from the center of the steel ball of the target ball along the axial direction of the opening circle.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
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