CN111207689A - Non-contact thread measuring device based on spectrum confocal principle - Google Patents
Non-contact thread measuring device based on spectrum confocal principle Download PDFInfo
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- CN111207689A CN111207689A CN202010053823.6A CN202010053823A CN111207689A CN 111207689 A CN111207689 A CN 111207689A CN 202010053823 A CN202010053823 A CN 202010053823A CN 111207689 A CN111207689 A CN 111207689A
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- reflector
- thread
- lens
- light
- measuring device
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/2425—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures of screw-threads
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/14—Measuring arrangements characterised by the use of optical techniques for measuring distance or clearance between spaced objects or spaced apertures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
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- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Microscoopes, Condenser (AREA)
Abstract
The invention provides a non-contact thread measuring device based on a spectrum confocal principle, which comprises a spectrum confocal lens and a reflector, wherein the reflector comprises a reflector surface and a bracket structure, the spectrum confocal lens is connected with the bracket structure of the reflector, one end of the spectrum confocal lens is provided with a light ray inlet, the spectrum confocal lens comprises a lens cone and a plurality of optical lenses, all the optical lenses are used as an optical system to disperse white light passing through the light ray inlet, and the dispersed white light is focused along the axial direction; the reflector splits and turns the light beam, and the light beam is finally focused on the surface of the trapezoidal thread to be measured; the cross section of the reflector surface is an isosceles triangle, the base angle is determined according to the inclination angle of the thread inclined plane to be measured, and after the light is reflected by the reflector, the central light and the thread inclined plane to be measured are ensured to be in a vertical relation. The invention can realize the non-contact method for measuring the profile of the trapezoidal thread, and further extract the thread pitch and the thread form angle.
Description
Technical Field
The invention relates to a measuring device, in particular to a thread measuring device.
Background
The thread is one of basic machines invented by human beings at the earliest time, is widely applied to the fields of spaceflight, chemical engineering, automobiles and the like due to the characteristics of easy assembly and convenient disassembly, and the used thread is generally detected by a thread gauge, and the thread amount is regularly measured by an instrument.
The currently common thread detection methods include:
(1) two-dimensional contact scanning measurement. The precise bearing is adopted to drive the measuring needle to carry out contact scanning on the thread, the grating system records the outline track coordinate in the scanning process, and finally, the software is used for synthesizing and calculating to obtain the comprehensive parameters of the thread.
(2) A non-contact measuring method based on a spectrum confocal principle.
The most approximate realization scheme of the invention is a thread parameter measuring device based on a spectrum confocal sensor. (CN 108592795A). The scheme utilizes a spectrum confocal measuring head to directly scan the thread profile (the optical axis of the measuring head is vertical to the motion direction of a motion platform where the thread to be measured is located) to obtain the profile curve of the thread. And obtaining two-dimensional thread parameters such as thread pitch, thread form angle, taper and the like according to the thread profile.
The existing spectrum confocal thread detection method has the following defects:
the designed measuring angle of the existing spectrum confocal measuring head which can be used for thread measurement is about 45 degrees at most, the measuring range is about 4mm, and although the spectrum confocal lens with larger angle and measuring range is available, the size and the cost are increased greatly. The increase in volume has no effect on the detection of the external thread, but the increase in the lens diameter for the detection of the internal thread results in a very limited type of thread to be detected (only threads having a diameter larger than the lens diameter can be detected). On the other hand, such a spectral confocal lens is feasible for detecting common threads, but cannot be used for detecting trapezoidal threads because the profile angle of trapezoidal threads is 30 °, that is, the flank angle is steeper, which makes it difficult to obtain an effective optical signal for the spectral confocal detection method.
The spectrum confocal detection principle is based on the principle of reflection, and light focuses on the surface to be detected, then gets back to the camera lens through reflection, and for the mirror surface, the design angle is 45 camera lens, can detect 45 inclined plane mirror surface at most, detects 45 inclined plane at most to mirror reflection, and when actually detecting ordinary screw thread, the surface of screw thread is generally the metal material, and does not belong to the mirror surface, and light focus can carry out diffuse reflection at the metal surface, so the spectrum confocal camera lens that the design angle is 45 can detect the metal inclined plane of bigger angle. The tooth form angle (bevel angle) of the common thread is 60 degrees, and empirical experiments prove that the profile of the common thread can be detected by detecting the thread by using a lens with a design angle of 45 degrees. But also undetectable for trapezoidal threads (ramp angle 75 °).
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a device for measuring the trapezoidal thread profile in a non-contact manner based on a spectrum confocal principle, which is used for scanning the measured trapezoidal thread profile and measuring parameters such as thread pitch, thread form angle and the like.
A non-contact thread measuring device based on a spectrum confocal principle comprises a spectrum confocal lens and a reflector, wherein the reflector comprises a reflector surface and a support structure, the spectrum confocal lens is connected with the support structure of the reflector, a light inlet is formed in one end of the spectrum confocal lens, the spectrum confocal lens comprises a lens cone and a plurality of optical lenses, all the optical lenses are used as an optical system to disperse white light passing through the light inlet, and the dispersed white light is focused along the axial direction; the reflector splits and turns the light beam, and the light beam is finally focused on the surface of the trapezoidal thread to be measured; the cross section of the reflector surface is an isosceles triangle, the base angle is determined according to the inclination angle of the thread inclined plane to be measured, and after the light is reflected by the reflector, the vertical relation between the central light and the thread inclined plane to be measured is ensured; the reflector is arranged near the focus of the light beam, and light rays are reflected by the thread surface and the reflector, finally enter the spectrum confocal lens again, are coupled into the optical fiber and are transmitted to a subsequent control system.
As a further improvement of the invention, the whole reflecting mirror and the spectrum confocal lens are connected through threads.
As a further improvement of the invention, the light inlet is an optical fiber, the optical fiber is a multimode optical fiber, and the numerical aperture is 0.1-0.3.
As a further improvement of the invention, the light inlet is a small hole, and the diameter of the small hole is 10-50 microns.
As a further improvement of the invention, the material of the lens barrel is selected from the materials with the thermal expansion coefficient less than or equal to 20.
As a further improvement of the invention, the optical lens is composed of 4-8 lenses, and the lens is a spherical lens or an aspheric lens.
As a further improvement of the invention, the reflector and the support structure are machined on a metal piece, and the reflector and the support structure are integrated.
As a further improvement of the present invention, the vertex angle portion of the mirror surface needs to be sufficiently sharp, and R <0.01mm is required if the radius of the fillet of the vertex angle portion is R.
The invention has the beneficial effects that:
a non-contact thread measuring device based on a spectrum confocal principle is provided with a light path design of an optical measuring head guided by two light beams; the structure design of the reflector of the optical measuring head with double-beam guiding is provided.
The invention can realize the non-contact method to measure the profile of the trapezoidal thread, and further extract the thread pitch and the thread form angle; the included angle between the two mirror surfaces of the reflector and the bottom surface can be designed into different angles, and the thread surfaces with different tooth form angles are measured.
Drawings
FIG. 1: a schematic view of a prior art trapezoidal thread profile;
FIG. 2: a prior art generic thread profile schematic;
FIG. 3: in the prior art, a spectrum confocal lens detects a thread outline schematic diagram;
FIG. 4: in the prior art, a spectrum confocal lens detects a schematic diagram of a mirror object;
FIG. 5: in the prior art, a spectrum confocal lens detects a thread outline schematic diagram;
FIG. 6: the invention is based on the spectrum confocal principle to measure the schematic diagram of the device of the trapezoidal thread;
FIG. 7: the device comprises a schematic diagram (I) of different parts of a measuring head detection thread;
FIG. 8: the device comprises a schematic diagram (II) of different parts of a measuring head detection thread;
FIG. 9: the overall structure of the reflector;
FIG. 10: a structure diagram of a reflector cut-open;
FIG. 11: mirror cut-away view (one);
FIG. 12: a mirror cut-away view (II);
FIG. 13: a schematic cross-sectional view of a reflector;
FIG. 14: the invention is a sectional view of the overall structure.
The names of the components in the figure are as follows:
Detailed Description
The invention is further described below with reference to the accompanying drawings.
A non-contact thread measuring device based on a spectrum confocal principle comprises a spectrum confocal lens 102 and a reflector 103, wherein the spectrum confocal lens 102 and the reflector are preferably connected in a threaded manner integrally, one end of the spectrum confocal lens 102 is provided with a light inlet 101, the light inlet 101 can be an optical fiber, a white light source is led in through the optical fiber, the optical fiber is a multimode optical fiber, and the numerical aperture is 0.1-0.3; the light inlet 101 may also be a small hole with a diameter of 10-50 microns.
The spectral confocal lens 102 includes a lens barrel and an optical lens, and the material of the lens barrel is generally selected to be a material with a low expansion coefficient (thermal expansion coefficient 20 and lower than 20) so as to prevent the optical element from being adversely affected by temperature drift and further reduce the measurement accuracy. The optical lenses are generally composed of 4-8 pieces, each lens can be a spherical lens or an aspherical lens, and all the optical lenses are used as an optical system to disperse white light passing through an optical fiber or a small hole and then focus along the axial direction after dispersion.
The mirror 106 splits and refracts the light beam, and the light beam is finally focused on the surface of the trapezoidal thread to be measured. The cross section of the reflector 106 is an isosceles triangle, the base angle is determined according to the inclination angle of the thread slope to be measured, and after the light is reflected by the reflector, the central light and the thread slope to be measured are ensured to be in a perpendicular relation, for example, the base angle is 62.5 degrees or other angles.
The reflector is arranged near the focus of the light beam, and light rays are reflected by the thread surface and the reflector, finally enter the spectrum confocal lens again, are coupled into the optical fiber and are transmitted to a subsequent control system.
The mirror surface 106 is machined on a metal piece, and the mirror surface 106 and the support structure are integrated, so that the whole rigidity is good, and the mirror surface cannot be easily damaged.
The light beam emitted from the optical fiber or the small hole is approximate to a Gaussian light beam, the energy of the central part is higher, the light beam which is partially reflected to the thread surface through the mirror surface of the reflector is required by the measuring equipment, the reflected light beam also exists at the vertex angle of the reflector, the reflected light beam is directly reflected back to the lens, the light beam is not required in detection and can influence the detection result, so that the vertex angle part of the reflector needs to be sharp enough, and R <0.01mm is required if the radius of the fillet of the vertex angle part is R.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (8)
1. The utility model provides a based on confocal principle non-contact screw thread measuring device of spectrum which characterized in that: the spectrum confocal white light source comprises a spectrum confocal lens (102) and a reflector (103), wherein the reflector (103) comprises a reflector surface (106) and a bracket structure, the spectrum confocal lens (102) is connected with the bracket structure of the reflector, a light inlet (101) is formed in one end of the spectrum confocal lens (102), the spectrum confocal lens (102) comprises a lens barrel and a plurality of optical lenses, all the optical lenses are used as an optical system to disperse white light passing through the light inlet (101), and the dispersed white light is focused along the axial direction; the reflecting mirror surface (106) splits and turns the light beam, and the light beam is finally focused on the surface of the trapezoidal thread to be measured; the cross section of the reflecting mirror surface (106) is an isosceles triangle, the base angle is determined according to the inclination angle of the thread inclined plane to be measured, and after the light is reflected by the reflecting mirror, the vertical relation between the central light and the thread inclined plane to be measured is ensured; the reflector is arranged near the focus of the light beam, and light rays are reflected by the thread surface and the reflector, finally enter the spectrum confocal lens again, are coupled into the optical fiber and are transmitted to a subsequent control system.
2. A non-contact thread measuring device based on spectral confocal principle according to claim 1, characterized in that: the whole reflecting mirror and the spectrum confocal lens (102) are connected through threads.
3. A non-contact thread measuring device based on spectral confocal principle according to claim 1, characterized in that: the light ray inlet (101) is an optical fiber, the optical fiber is a multimode optical fiber, and the numerical aperture is 0.1-0.3.
4. A non-contact thread measuring device based on spectral confocal principle according to claim 1, characterized in that: the light inlet (101) is a small hole, and the diameter of the small hole is 10-50 microns.
5. A non-contact thread measuring device based on spectral confocal principle according to claim 1, characterized in that: the material of the lens cone is selected from a material with a thermal expansion coefficient less than or equal to 20.
6. A non-contact thread measuring device based on spectral confocal principle according to claim 1, characterized in that: the optical lens is composed of 4-8 lenses, and the lens is a spherical lens or an aspheric lens.
7. A non-contact thread measuring device based on spectral confocal principle according to claim 1, characterized in that: the reflector (106) and the support structure are machined on a metal piece, and the reflector and the support structure are integrated.
8. A non-contact thread measuring device based on spectral confocal principle according to claim 1, characterized in that: the vertex angle portion of the mirror surface needs to be sufficiently sharp, and if the radius of the fillet of the vertex angle portion is R, R <0.01mm is required.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010053823.6A CN111207689A (en) | 2020-01-17 | 2020-01-17 | Non-contact thread measuring device based on spectrum confocal principle |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010053823.6A CN111207689A (en) | 2020-01-17 | 2020-01-17 | Non-contact thread measuring device based on spectrum confocal principle |
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| CN111207689A true CN111207689A (en) | 2020-05-29 |
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| CN202010053823.6A Pending CN111207689A (en) | 2020-01-17 | 2020-01-17 | Non-contact thread measuring device based on spectrum confocal principle |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111879505A (en) * | 2020-07-08 | 2020-11-03 | 常州海通石油管业有限公司 | Oil pipe thread detection device for high-pressure oil-gas well operation |
| CN113375550A (en) * | 2021-04-25 | 2021-09-10 | 山西迪迈沃科光电工业有限公司 | Non-contact internal thread detection device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101221039A (en) * | 2007-12-30 | 2008-07-16 | 苏州雷神科技有限公司 | Screw tooth detecting method and detecting device thereof |
| CN208296778U (en) * | 2018-05-16 | 2018-12-28 | 深圳市中图仪器股份有限公司 | A kind of multi-measuring point Spectral Confocal gauge head |
-
2020
- 2020-01-17 CN CN202010053823.6A patent/CN111207689A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101221039A (en) * | 2007-12-30 | 2008-07-16 | 苏州雷神科技有限公司 | Screw tooth detecting method and detecting device thereof |
| CN208296778U (en) * | 2018-05-16 | 2018-12-28 | 深圳市中图仪器股份有限公司 | A kind of multi-measuring point Spectral Confocal gauge head |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111879505A (en) * | 2020-07-08 | 2020-11-03 | 常州海通石油管业有限公司 | Oil pipe thread detection device for high-pressure oil-gas well operation |
| CN111879505B (en) * | 2020-07-08 | 2022-02-08 | 常州海通石油管业有限公司 | Oil pipe thread detection device for high-pressure oil-gas well operation |
| CN113375550A (en) * | 2021-04-25 | 2021-09-10 | 山西迪迈沃科光电工业有限公司 | Non-contact internal thread detection device |
| CN113375550B (en) * | 2021-04-25 | 2022-09-20 | 山西迪迈沃科光电工业有限公司 | Non-contact internal thread detection device |
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Application publication date: 20200529 |
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