Laser length measuring system of ball screw dynamic stroke error measuring instrument

Abstract

The utility model provides a laser length measuring system of a ball screw dynamic stroke error measuring instrument, and belongs to the technical field of precision measurement. The laser head, the receiver and the pyramid reflector are arranged in parallel, the laser head and the receiver are located on one side of the lead screw, and the pyramid reflector is located on the other side of the lead screw; the spectroscope divides the laser into a light beam 1 and a light beam 2, and the light beam 2 is reflected by the reflector and then enters the receiver; the trihedral corner reflector base is installed on the workbench installed on the lead screw, the first plane mirror, the second plane mirror and the third plane mirror form a corner reflector which is installed on the trihedral corner reflector base, and the intersection point O of the corner reflector coincides with the lead screw measuring point; the pyramid reflector is located on a light path of reflected light through the corner reflector. During working, the workbench moves along the axis of the lead screw, the equivalent measuring point of the laser length measuring system always coincides with the target measuring point of the lead screw, the moving distance of the measuring point of the lead screw is converted into the length of the light path length change, and the Abbe error can be fundamentally eliminated.

Description

Technical Field

[0001] The utility model belongs to the technical field of precision measurement, relates to the field of precision detection of ball screws, and particularly relates to a laser length measurement system of a dynamic stroke error measuring instrument for ball screws. Background Art

[0002] The Abbe error is the main source of the measurement error of the laser length measurement system of the measuring instrument. Suppressing or eliminating the Abbe error is the key to improving the measurement accuracy of the laser length measurement system. The root cause of the Abbe error is that the actual measurement point does not coincide with the target measurement point, and the moving trajectories of the two deviate due to the angular error during the movement of the displacement stage, as shown in Figure 1 .

[0003] Currently, there are mainly two methods for the laser length measurement system to suppress the Abbe error. One is to improve the moving position accuracy of the displacement stage; the other is to simultaneously measure through multiple laser length measurement optical paths, model and separate the Abbe error, and then perform compensation. Patent document CN1510390A discloses a large-length laser interference length measurement system for eliminating the Abbe error, which compensates by modeling and separating the Abbe error through a triangular prism layout of the optical path. The invention patent with the publication number CN1252444C discloses a length measurement system that realizes simultaneous length measurement of multiple optical paths through three beam splitters and receivers. The above methods can compensate the Abbe error to a certain extent. However, the former uses a displacement stage with higher accuracy, resulting in a significant increase in the measurement cost; the latter has high requirements for the positional accuracy between the optical paths during measurement, and is difficult to debug and install, making it difficult to completely eliminate the Abbe error and prone to introducing errors caused by signal asynchronization. Currently, no length measurement system that directly eliminates the Abbe error through single-path laser measurement has been found. Summary of the Invention

[0004] Aiming at the above problems, the utility model provides a new laser length measurement system for a measuring instrument. The system realizes the coincidence of the actual measurement point and the target measurement point through a single-path design, thereby fundamentally eliminating the influence of the Abbe error on the measurement accuracy of the measuring instrument.

[0005] In order to achieve the above object, the technical solution adopted by the utility model is as follows:

[0006] A laser length measurement system of a dynamic stroke error measuring instrument for ball screws, characterized in that it includes a laser head, a receiver, a reflector, a beam splitter, a corner cube reflector, a first plane mirror, a second plane mirror, a third plane mirror, and a corner cube reflector base. The laser head and the corner cube reflector are respectively fixed on both sides of one end of the bed body. The receiver and the laser head are arranged side by side on the same side of the bed body. The beam splitter is installed at the front end of the laser head and is located on the laser output optical path. The beam splitter divides the laser into beam one and beam two, and beam two is reflected by the reflector and then incident on the receiver.

[0007] The base of the trihedral corner reflector is installed on a workbench driven by a lead screw. Measuring points for indicating the moving distance driven by the lead screw are provided on the workbench. The planes where the first plane mirror, the second plane mirror, and the third plane mirror are located are pairwise orthogonal and are all installed on the base of the trihedral corner reflector. The intersection point O of the planes where the first plane mirror, the second plane mirror, and the third plane mirror are located coincides with the measuring point on the workbench. The second plane mirror is installed in the middle of the base of the trihedral corner reflector and forms an angle of 35 ± 10° with the horizontal plane where the bed body is located. The first plane mirror and the third plane mirror are located on both sides of the second plane mirror, and the first plane mirror is located on the optical path of the light beam split by the beam splitter. The light beam is reflected by the first plane mirror and then irradiates on the second plane mirror, and then is reflected by the second plane mirror to the third plane mirror. The corner cube reflector is located on the optical path of the light beam reflected by the third plane mirror. The light beam reflected by the third plane mirror is incident on the corner cube reflector, and after being reflected by the corner cube reflector, the light beam passes through the third plane mirror, the second plane mirror, and the first plane mirror in sequence, and then is incident on the receiver through the beam splitter and the mirror.

[0008] Further, the first plane mirror and the third plane mirror are symmetrically arranged on both sides of the second plane mirror.

[0009] Further, the laser head, the beam splitter, and the first plane mirror are all located on the first optical axis. The third plane mirror and the corner cube reflector are located on the second optical axis. The mirror and the receiver are located on the propagation path of the third optical axis. The first optical axis, the second optical axis, and the third optical axis are all parallel to the axis of the lead screw and are in the same horizontal plane as the axis of the lead screw.

[0010] Further, the laser head, the receiver, the beam splitter, and the corner cube reflector are all installed on a mounting bracket fixed to the bed body.

[0011] Further, the frequency range of the laser emitted by the laser head is 1.9 to 2.4 MHz.

[0012] The present utility model ingeniously sets the reflecting device and the optical path, making the intersection point of the corner reflector formed by the first plane mirror, the second plane mirror, and the third plane mirror coincide with the point to be measured, converting the moving distance of the measuring point of the lead screw into the change in the optical path length, and fundamentally eliminating the Abbe error. Moreover, the structure of the present utility model is simple, the manufacturing cost is low, and it is conducive to wide industrial application. Description of the Drawings

[0013] Figure 1 It is a schematic diagram of the Abbe error.

[0014] Figure 2 It is a schematic structural diagram of the laser length measuring system of the ball screw dynamic stroke error measuring instrument of the present utility model.

[0015] Figure 3This is a schematic diagram of the laser optical path of the laser length measuring instrument for the dynamic stroke error measuring instrument of the ball screw of the present utility model.

[0016] Figure 4 This is a schematic diagram of the beam reflection path of the corner reflector composed of the first plane mirror, the second plane mirror, and the third plane mirror when the tilt angle of the second plane mirror is 35°.

[0017] Figure 5 This is a schematic diagram of the beam reflection path of the laser length measuring system of the ball screw dynamic stroke error measuring instrument of the present invention.

[0018] Figure 6 This is a schematic diagram of the installation structure of the first plane mirror 6, the second plane mirror 7, and the third plane mirror 9.

[0019] Figure 7 This is a schematic diagram of the length measuring principle of the laser length measuring system of the ball screw dynamic stroke error measuring instrument of the present invention.

[0020] In the figure: 1. Laser head; 2. Receiver; 3. Reflecting mirror; 4. Beam splitter; 5. Corner cube reflector; 6. First plane mirror; 7. Second plane mirror; 8. Bed; 9. Third plane mirror; 10. Corner cube reflector base; 11. Workbench; 12. Ball screw; 13. Mounting bracket. Detailed implementation mode

[0021] In order to make the purpose, technical solution and advantages of the present utility model clearer, the present utility model will be described in detail below with reference to the accompanying drawings.

[0022] As Figure 2 shown, the laser length measuring system of the ball screw dynamic stroke error measuring instrument of the present invention includes a laser head 1, a receiver 2, a reflecting mirror 3, a beam splitter 4, a corner cube reflector 5, a first plane mirror 6, a second plane mirror 7, a third plane mirror 9, and a corner cube reflector base 10. Specifically, the ball screw 12 is installed on the bed 8, the workbench 11 is installed on the ball screw, and is driven by the ball screw 12 to move left and right along the axial direction of the ball screw 12 on the bed. A measuring point for indicating the moving distance driven by the ball screw 12 is provided on the workbench 11. The above structures are all installed on the bed 8 and the workbench 11 for measuring the stroke of the ball screw 12.

[0023] As Figure 5As shown in the figure, specifically, the mounting bracket 13 is fixedly installed above one end of the bed body 8. The laser head 1, the receiver 2, the reflecting mirror 3, the beam splitter 4 and the corner cube reflector 5 are all fixed on the mounting bracket 13. Among them, the laser head 1, the receiver 2 and the corner cube reflector 5 are arranged in parallel, and the laser head 1 and the receiver 2 are located on one side of the lead screw 12, while the corner cube reflector 5 is located on the other side of the lead screw 12. The beam splitter 4 is installed at the front end of the laser head 1 and is located on the laser light output path. The beam splitter 4 divides the laser into beam 1 propagating along the original path and beam 2 perpendicular to beam 1. The reflecting mirror 3 is installed on the light path of beam 2 and reflects beam 2 to the receiver 2.

[0024] As Figures 3 - 6 shown, the trihedral corner reflector base 10 is installed on the workbench 11. The planes where the first plane mirror 6, the second plane mirror 7 and the third plane mirror 9 are located are orthogonal to each other pairwise and are all installed on the trihedral corner reflector base 10. The intersection point O of the planes where the first plane mirror 6, the second plane mirror 7 and the third plane mirror 9 are located coincides with the measuring point of the workbench on the measured lead screw. The second plane mirror 7 is installed in the middle of the trihedral corner reflector base 10 and the included angle with the horizontal plane where the bed body 8 is located is 35 ± 10°. The first plane mirror 6 and the third plane mirror 9 are located on both sides of the second plane mirror 7. And the first plane mirror 6 is located on the light path of beam 1 divided by the beam splitter 4 and the included angle with the second plane mirror 7 is an acute angle. Beam 1 is reflected by the first plane mirror 6 and then irradiates on the second plane mirror 7, and then is reflected by the second plane mirror 7 to the third plane mirror 9. The corner cube reflector 5 is located on the light path of the light reflected by the third plane mirror 9.

[0025] As Figure 3 shown, the laser head 1, the beam splitter 4 and the first plane mirror 6 are all located on optical axis 1. The third plane mirror 9 and the corner cube reflector 5 are located on optical axis 2. The reflecting mirror 3 and the receiver 2 are located on the propagation path of optical axis 3. Optical axis 1, optical axis 2 and optical axis 3 are all parallel to the axis of the lead screw 12 and are in the same horizontal plane as the axis of the lead screw 12. Figure 4 It shows the beam reflection path of the corner reflector formed by the first plane mirror 6, the second plane mirror 7 and the third plane mirror 9 when the included angle between the second plane mirror 7 and the horizontal plane where the bed body 8 is located is 35°. As shown in the figure, when beam 1 is incident on the first plane mirror 6, the included angle between beam 1 and the outgoing light ray reflected by the first plane mirror 6 is 109°; the outgoing light ray of the first plane mirror 6 is incident on the second plane mirror 7 and then reflected to the third plane mirror 9. The included angle between the incident light ray and the outgoing light ray of the second plane mirror 7 is 110°, and the included angle between the incident light ray and the outgoing light ray of the third plane mirror 9 is 109°.

[0026] As Figure 5As shown in the figure, specifically, the laser head 1 emits a length measurement beam, which is split into two perpendicular length measurement beams by the beam splitter 4: beam one and beam two. Beam two is directly incident on the receiver 2 through the mirror 3. Beam one is reflected by the first plane mirror 6, the second plane mirror 7, and the third plane mirror 9 in sequence and then incident on the corner cube mirror 5. The parallel beam reflected by the corner cube mirror 5 is incident on the receiver 2 through the third plane mirror 9, the second plane mirror 7, the first plane mirror 6, the beam splitter 4, and the mirror 3 in sequence.

[0027] As Figure 7 shown, the sum of the optical path lengths of the laser length measurement system is denoted as L 总 , O1 is the reflection point of the first plane mirror 6, O2 is the reflection point of the second plane mirror 7, O3 is the reflection point of the third plane mirror 9, O is the intersection point of the first plane mirror 6, the second plane mirror 7, and the third plane mirror 9, and it is also the measuring point of the lead screw. B0 is the reflection point of the corner cube mirror.

[0028] L 总 = A0O1 + O1O2 + O2O3 + O3B0

[0029] The symmetric point of the laser emission point A0 with respect to the first plane mirror 6 is denoted as A1, the symmetric point of A1 with respect to the second plane mirror 7 is A2, and the symmetric point of A2 with respect to the second plane mirror 7 is A3. Therefore, A0 and A3 are centrosymmetric with respect to point O.

[0030] According to the law of reflection, it can be deduced that A1O1 and O1O2 are collinear, and:

[0031] A0O1 = A1O1

[0032] Similarly, it can be obtained that:

[0033] A1O2 = A2O2

[0034] A2O3 = A3O3

[0035] From this, it can be known that:

[0036] A 3 B 0 = L total

[0037] Specifically, A0 and A3 are centrosymmetric with respect to point O. The distance L0 that the measuring point O of the lead screw moves along the axis is:

[0038]

[0039] Specifically, when the laser emission point A0 and the measuring point O of the lead screw do not move, the workbench 11 drives the corner cube mirror base 10 to generate an arbitrary angular deviation, the position of A3 remains unchanged, and the optical path length L of the laser length measurement system 总 remains unchanged. Therefore, this laser length measurement system can effectively eliminate the influence of Abbe error.

[0040] The receiver 2 first obtains the length of the entire transmission path of Beam 1 in this initial state, i.e., 2L, according to the time difference Δt1 between the received Beam 2 and the reflected Beam 1 before the lead screw moves. 总1 ; then, after the lead screw moves, the receiver 2 obtains the length of the entire transmission path of Beam 1 at this time, i.e., 2L, according to the time difference Δt2 between the received Beam 2 and the reflected Beam 1. 总2 ; then, from the difference between L 总1 and L 总2 , i.e., ΔL 总 the moving distance L0 of the measuring point of the lead screw 12 is obtained.

[0041] The above embodiments only represent the implementation modes of the present utility model, but should not be construed as limiting the scope of the present invention patent. It should be noted that for those skilled in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A laser length measuring system for a dynamic stroke error measuring instrument of a ball screw, characterized in that, It includes a laser head (1), a receiver (2), a reflector (3), a beam splitter (4), a corner cube reflector (5), a first plane mirror (6), a second plane mirror (7), a third plane mirror (9), and a corner cube mirror base (10). The laser head (1) and the corner cube reflector (5) are respectively fixed on both sides of one end of the bed body (8). The receiver (2) and the laser head (1) are located on the same side of the bed body (8) and arranged side by side. The beam splitter (4) is installed at the front end of the laser head (1) and is located on the laser output optical path. The beam splitter (4) divides the laser into a first light beam and a second light beam. The second light beam is reflected by the reflector (3) and then incident on the receiver (2). The corner cube mirror base (10) is installed on a workbench (11) driven by a lead screw (12). There are measuring points on the workbench (11) for indicating the moving distance driven by the lead screw (12). The planes where the first plane mirror (6), the second plane mirror (7), and the third plane mirror (9) are located are pairwise orthogonal and are all installed on the corner cube mirror base (10). The intersection point O of the planes where the first plane mirror (6), the second plane mirror (7), and the third plane mirror (9) are located coincides with the measuring point on the workbench (11). The second plane mirror (7) is installed in the middle of the corner cube mirror base (10) and forms an angle of 35 ± 10° with the horizontal plane where the bed body (8) is located. The first plane mirror (6) and the third plane mirror (9) are located on both sides of the second plane mirror (7). And the first plane mirror (6) is located on the optical path of the first light beam divided by the beam splitter (4). The first light beam is reflected by the first plane mirror (6) and then irradiated on the second plane mirror (7), and then reflected by the second plane mirror (7) to the third plane mirror (9). The corner cube reflector (5) is located on the optical path of the light beam reflected by the third plane mirror (9). The light beam reflected by the third plane mirror (9) is incident on the corner cube reflector (5). After being reflected by the corner cube reflector (5), it is reflected by the third plane mirror (9), the second plane mirror (7), and the first plane mirror (6) in sequence, and then incident on the receiver (2) through the beam splitter (4) and the reflector (3).

2. The laser length measuring system of the ball screw dynamic stroke error measuring instrument according to claim 1, wherein The first plane mirror (6) and the third plane mirror (9) are symmetrically arranged on both sides of the second plane mirror (7).

3. The laser length measuring system of the ball screw dynamic stroke error measuring instrument according to claim 1, characterized in that The laser head (1), the beam splitter (4), and the first plane mirror (6) are all located on the first optical axis. The third plane mirror (9) and the corner cube reflector (5) are located on the second optical axis. The reflector (3) and the receiver (2) are located on the propagation path of the third optical axis. The first optical axis, the second optical axis, and the third optical axis are all parallel to the axis of the lead screw (12) and are in the same horizontal plane as the axis of the lead screw (12).

4. The laser length measuring system of the ball screw dynamic stroke error measuring instrument according to claim 1, characterized in that The laser head (1), the receiver (2), the beam splitter (4), and the corner cube reflector (5) are all installed on a mounting bracket (13) fixed on the bed body (8).

5. The laser length measuring system of the ball screw dynamic stroke error measuring instrument according to claim 1, characterized in that, The frequency range of the laser emitted by the laser head (1) is 1.9 to 2.4 MHz.

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