Laser welding spectral monitoring instrument

Abstract

This utility model discloses a laser welding spectral monitoring instrument, belonging to the field of spectral detection technology. It includes a monitoring device with an internal spectral monitoring main control circuit board, a first filter, a first photodiode, a second filter, a second photodiode, a third filter, a third photodiode, a first dichroic mirror, and a second dichroic mirror. A reflecting device is located below the monitoring device, and the reflecting device includes a first beam splitter and a connecting tube. The first, second, and third photodiodes are all connected to the spectral monitoring main control circuit board. This utility model provides a solution to the problem that existing spectral monitoring instruments can only monitor a limited wavelength range.

Description

Technical Field

[0001] This utility model belongs to the field of spectral detection technology and relates to a spectral monitoring instrument for laser welding. Background Technology

[0002] Currently, laser monitoring of the laser welding process mainly utilizes high-speed infrared cameras, photodiodes, pyrometers, and photomultiplier tubes. These devices are very attractive for monitoring laser processing; however, these types of sensors are typically sensitive only within a limited spectral range. For example, silicon photodiodes are commonly used for ultraviolet and visible light wavelengths, while germanium and InGaAs photodiodes are preferred for visible to infrared light detection.

[0003] Laser welding generates a wide spectral range, with the molten pool's infrared thermal radiation covering the infrared spectrum (typically 1200nm-1800nm), while plasma emission extends from near-ultraviolet to visible wavelengths (typically 350nm-700nm). The laser's interaction with the material itself produces reflected light (typically 1060nm–1090nm). Currently, existing monitoring instruments often only monitor a limited wavelength range, failing to accurately monitor the various complex situations that arise during laser processing. Their monitoring functions are limited and their applicability narrow. Some manufacturers use multiple monitoring instruments capable of detecting different spectral bands, resulting in complex and bloated systems, and incurring significant monitoring costs. Utility Model Content

[0004] This invention provides a laser welding spectral monitoring instrument to solve the problem that existing spectral monitoring instruments can only monitor the spectrum within a limited wavelength range.

[0005] To solve the above problems, the technical solution adopted by this utility model is as follows: A monitoring device includes an internal spectral monitoring main control circuit board, a first filter, a first photodiode, a second filter, a second photodiode, a third filter, a third photodiode, a first dichroic mirror, and a second dichroic mirror. Below the monitoring device is a reflecting device, which includes a first beam splitter and a connecting tube. The connecting tube is used to connect to the laser welding head. The first beam splitter is a 5:5 beam splitter, capable of reflecting 50% of the incident laser welding spectrum (350-1800nm) to the second dichroic mirror in the longitudinal optical path. The second dichroic mirror is a wavelength-selective optical lens with the characteristics of reflecting light in the 350-700nm band and transmitting light in the 700-1800nm ​​band. The first dichroic mirror is also a wavelength-selective optical lens with the characteristics of reflecting light in the 1060-1090nm band and transmitting light in the 1200-1800nm ​​band. The first filter, the first dichroic mirror, the second dichroic mirror, and the first beam splitter are arranged in a vertical optical path from top to bottom. The first filter is a 1200-1800nm ​​narrowband filter. The first photodiode is disposed above the first filter with its photosensitive surface facing the first filter. It is used to receive 1200-1800nm ​​wavelength light transmitted by the first dichroic mirror and purified by the first filter. The second filter and the first dichroic mirror are distributed from left to right to form a first transverse optical path. The second filter is a 1060-1090nm narrowband filter. The second photodiode is correspondingly disposed on the left side of the second filter, with its photosensitive surface facing the second filter. It is used to receive 1060-1090nm band light reflected by the first dichroic mirror and purified by the second filter. The third filter and the second dichroic mirror are distributed from left to right to form a second transverse optical path. The third filter is a 350-700nm narrowband filter. The third photodiode is correspondingly disposed on the left side of the third filter, with its photosensitive surface facing the third filter. It is used to receive the 350-700nm band light reflected by the second dichroic mirror and purified by the third filter. The 700-1800nm ​​band light transmitted by the second dichroic mirror is transmitted along the longitudinal optical path to the first dichroic mirror. The first beam splitter is tilted relative to the longitudinal optical path and faces the first filter (for guiding 50% of the welding spectrum into the longitudinal optical path), the first dichroic mirror is tilted relative to the first transverse optical path and faces the second filter (for guiding the reflected 1060-1090nm light into the second filter), and the second dichroic mirror is tilted relative to the second transverse optical path and faces the third filter (for guiding the reflected 350-700nm light into the third filter). The first photodiode, the second photodiode, and the third photodiode are all connected to the main control circuit board for spectral monitoring, which can convert the detected optical signals of different bands into current signals. The main control circuit board for spectral monitoring is used to amplify, filter, demodulate, convert A / D and process the current signals, and to determine the welding status by analyzing the changes in the intensity of the three bands of the spectrum.

[0006] A more specific technical solution in the above technical solution may be: a first focusing lens is provided between the first filter and the first dichroic mirror, the optical axis of the first focusing lens is collinear with the longitudinal optical path, and is used to focus the 1200-1800nm ​​light transmitted by the first dichroic mirror onto the first filter, thereby improving the filtering efficiency and the light signal intensity, and ensuring that the light signal is received by the first photodiode.

[0007] Furthermore, a second focusing lens is provided between the second filter and the first dichroic mirror. The optical axis of the second focusing lens is collinear with the first transverse optical path, which is used to focus the 1060-1090nm light reflected by the first dichroic mirror onto the second filter, thereby improving the filtering efficiency and the intensity of the optical signal and ensuring that the optical signal is received by the second photodiode.

[0008] Furthermore, a third focusing lens is provided between the third filter and the second dichroic mirror. The optical axis of the third focusing lens is collinear with the second transverse optical path, and is used to focus the 350-700nm light reflected by the second dichroic mirror onto the third filter, thereby improving the filtering efficiency and the intensity of the optical signal and ensuring that the optical signal is received by the third photodiode.

[0009] Furthermore: a second beam splitter is provided between the third focusing lens and the second dichroic mirror. The second beam splitter is tilted relative to the second transverse optical path and faces the second dichroic mirror. A red light indicator is detachably installed on the housing wall of the monitoring device through a fixing plate and bolt assembly. The light outlet of the red light indicator is aligned with the second beam splitter, and the second beam splitter can reflect red light to the longitudinal optical path and project it onto the welding area through the first beam splitter.

[0010] Furthermore: the first beam splitter is mounted on the bottom shell wall of the reflecting device via a frame and adjusting bolts. By rotating the adjusting bolts, the angle at which the first beam splitter is aligned with the connecting tube can be adjusted so that the light generated by external welding can be transmitted coaxially to the inside of the monitoring device.

[0011] By adopting the above technical solution, this utility model has the following beneficial effects compared with the prior art: Through the synergistic spectral dispersion of the first dichroic mirror (reflection 1060-1090nm, transmission 1200-1800nm) and the second dichroic mirror (reflection 350-700nm, transmission 700-1800nm), combined with narrowband filters of corresponding wavelengths, a three-channel monitoring system covering 350-700nm (plasma emission light), 1060-1090nm (laser reflection light), and 1200-1800nm ​​(molten pool infrared thermal radiation) is constructed, completely capturing the core spectral information of the laser welding process. Compared with existing instruments that can only monitor a single spectral band, or complex solutions requiring multiple devices, this solution, through integrated design, can cover a longer monitoring range during laser processing, and has a simple structure, enabling real-time, accurate, and rapid laser welding monitoring. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of this utility model.

[0013] Figure 2 yes Figure 1 Internal structure diagram from the K-direction view.

[0014] Figure 3 This is the optical path schematic diagram of this utility model.

[0015] In the diagram: 1. Monitoring device; 2. Reflecting device; 3. Connecting pipe; 4. Red light indicator; 5. Fixing plate; 6. Spectral monitoring main control circuit board; 7. First beam splitter; 8. Second beam splitter; 9. First dichroic mirror; 10. Second dichroic mirror; 11. First focusing lens; 12. First filter; 13. First photodiode; 14. Second focusing lens; 15. Second filter; 16. Second photodiode; 17. Third focusing lens; 18. Third filter; 19. Third photodiode; 20. Adjusting bolt; 21. Frame. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and examples: It should be noted in the description that the terms "upper", "lower", "left" and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0017] like Figures 1 to 3The laser welding spectral monitoring instrument shown includes a monitoring device 1 with an internal spectral monitoring main control circuit board 6. Inside the monitoring device 1, a first filter 12, a first photodiode 13, a first focusing lens 11, a second filter 15, a second photodiode 16, a second focusing lens 14, a third filter 18, a third photodiode 19, a third focusing lens 17, a first dichroic mirror 9, a second dichroic mirror 10, and a second beam splitter 8 are mounted via brackets and bolts. A reflecting device 2 is located below the monitoring device 1. The reflecting device 2 includes a first beam splitter 7 and a connecting pipe 3. The first beam splitter 7 is mounted on the bottom shell wall of the reflecting device 2 via a lens frame 21 and bolts. Adjustment is achieved by rotating the adjusting bolt 2. The rotation of the frame 21 adjusts the angle of the first beam splitter 7 aligned with the connecting tube 3, allowing the light generated by external welding to be coaxially transmitted to the monitoring device 1. The connecting tube 3 is used to connect to the laser welding head. The first filter 12, the first focusing lens 11, the first dichroic mirror 9, the second dichroic mirror 10, and the first beam splitter 7 are arranged from top to bottom to form a longitudinal optical path. The first photodiode 13 is positioned above the first filter 12, with its photosensitive surface facing the first filter 12, and is used to receive the 1200-1800nm ​​light transmitted by the first dichroic mirror 9 and purified by the first filter 12. The second filter 15, the second focusing lens 14, and the first dichroic mirror 9 are arranged from left to right to form the first beam splitter 11. In the transverse optical path, the second photodiode 16 is positioned to the left of the second filter 15, with its photosensitive surface facing the second filter 15. It receives 1060-1090nm light after reflection by the first dichroic mirror 9 and purification by the second filter 15. The third filter 18, the third focusing mirror 17, the second beam splitter 8, and the second dichroic mirror 10 are distributed from left to right to form the second transverse optical path. The third photodiode 19 is positioned to the left of the third filter 18, with its photosensitive surface facing the third filter 18. It receives 350-700nm light after reflection by the second dichroic mirror 10 and purification by the third filter 18. The 700-1800nm ​​light transmitted through the second dichroic mirror 10 travels along the longitudinal optical path. The light is transmitted to the first dichroic mirror 9; the first beam splitter 7 is tilted at 45° relative to the longitudinal light path and faces the first filter 12; the first dichroic mirror 9 is tilted at 45° relative to the first transverse light path and faces the second filter 15; the second dichroic mirror 10 is tilted at 45° relative to the second transverse light path and faces the third filter 18; the second beam splitter 8 is tilted at 45° relative to the second transverse light path and faces the second dichroic mirror 10; the housing of the monitoring device 1 is detachably mounted with a red light indicator 4 via a fixing plate 5 and a bolt assembly; the light outlet of the red light indicator 4 is aligned with the second beam splitter 8; and the second beam splitter 8 can reflect red light to the longitudinal light path, which is then projected onto the welding area via the first beam splitter 7.

[0018] In this example, both the first beam splitter 7 and the second beam splitter 8 are 5:5 beam splitters. Both the first dichroic mirror 9 and the second dichroic mirror 10 are wavelength-selective optical lenses. The second dichroic mirror 10 reflects light in the 350-700nm range and transmits light in the 700-1800nm ​​range. The first dichroic mirror 9 reflects light in the 1060-1090nm range and transmits light in the 1200-1800nm ​​range. The first filter 12 is a narrowband filter in the 1200-1800nm ​​range, the second filter 15 is a narrowband filter in the 1060-1090nm range, and the third filter 18 is a narrowband filter in the 350-700nm range.

[0019] In use, the red light emitted by the red light indicator 4 is reflected to the welding area by the second beam splitter 8, the second dichroic mirror 10, and the first beam splitter 7. The spectrum (350-1800nm) generated during the laser welding process passes through the first beam splitter 7, with 50% of the light transmitted to the second dichroic mirror 10 in the longitudinal optical path. When the light passes through the second dichroic mirror 10, the 350-700nm light passes sequentially through the second beam splitter 8, the third focusing mirror 17, and the third filter 18 to the third photodiode 19. When the 700-1800nm ​​light transmitted through the second dichroic mirror 10 is transmitted to the first dichroic mirror 9, the 1060-1090nm light passes sequentially through the second focusing mirror 14 and the second filter 15 to the second photodiode 16. The 1200-1800nm ​​light transmitted through the first dichroic mirror 9 passes sequentially through the first focusing mirror 11 and the first filter 12 to the first photodiode 13. The first photodiode 13, the second photodiode 16, and the third photodiode 19 detect light in different wavelength bands to form current. The current-to-voltage amplification, filtering, demodulation, and A / D conversion are achieved through the spectral monitoring main control circuit board 6. Then, data processing and image construction are performed. Since the intensity of the detected three-band spectrum will change significantly when welding is abnormal, the welding is judged based on the strength of the change, thereby realizing the monitoring of the welding process.

[0020] It should be noted that the spectral monitoring main control circuit board 6 provided by this utility model is a common device in the prior art. It only needs to be connected according to the connection relationship given in the embodiment of this utility model. The technical solution of this utility model can be obtained by conventionally setting the spectral monitoring main control circuit board 6, without involving any improvement in control methods or software. As for the parameter settings and usage methods of the spectral monitoring main control circuit board 6, those skilled in the art can purchase the spectral monitoring main control circuit board 6 and refer to the accompanying instruction manual, and will not be described in detail here.

Claims

1. A laser welding spectral monitor characterized by: The monitoring device includes an internal spectral monitoring main control circuit board, a first filter, a first photodiode, a second filter, a second photodiode, a third filter, a third photodiode, a first dichroic mirror, and a second dichroic mirror. A reflecting device is located below the monitoring device, comprising a first beam splitter and a connecting tube. The first filter, the first dichroic mirror, the second dichroic mirror, and the first beam splitter are arranged sequentially from top to bottom to form a longitudinal optical path. The first photodiode is correspondingly positioned above the first filter. The second filter and the first dichroic mirror are arranged from left to right to form a first transverse optical path. A photodiode is positioned to the left of the second filter. The third filter and the second dichroic mirror are distributed from left to right to form a second transverse optical path. The third photodiode is positioned to the left of the third filter. The first beam splitter is tilted relative to the longitudinal optical path and faces the first filter. The first dichroic mirror is tilted relative to the first transverse optical path and faces the second filter. The second dichroic mirror is tilted relative to the second transverse optical path and faces the third filter. The first photodiode, the second photodiode, and the third photodiode are all connected to the spectral monitoring main control circuit board.

2. The laser welding spectral monitor of claim 1, wherein: A first focusing lens is provided between the first filter and the first dichroic mirror.

3. The laser welding spectral monitor of claim 2, wherein: A second focusing lens is provided between the second filter and the first dichroic mirror.

4. The laser welding spectral monitoring instrument according to claim 3, characterized in that: A third focusing lens is provided between the third filter and the second dichroic mirror.

5. The laser welding spectral monitoring instrument according to claim 4, characterized in that: A second beam splitter is provided between the third focusing lens and the second dichroic mirror. The second beam splitter is tilted relative to the second transverse optical path and faces the second dichroic mirror. The monitoring device is equipped with a red light indicator, and the light outlet of the red light indicator is aligned with the second beam splitter.

6. The laser welding spectral monitoring instrument according to claim 5, characterized in that: The first beam splitter is mounted on the bottom of the reflecting device via a frame and bolts.

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