Laser welding penetration online detection system

Abstract

The utility model relates to the technical field of laser welding, and discloses a laser welding fusion depth on-line detection system which comprises a spectrum analyzer, an optical lens group, a first detection sensor and a reflective mirror, laser is emitted to the optical lens group through the first detection sensor, the laser is divided into two beams through the optical lens group, one beam of laser is emitted to a weld joint of an object to be welded to serve as signal light, the other beam of laser is emitted to the reflector to serve as reference light, the signal light and the reference light return to the spectrum analyzer after being reflected, when the lengths of the signal light and the reference light are consistent, interference occurs to form an interference spectrum, and the interference spectrum is analyzed through the spectrum analyzer to obtain a welding result. And obtaining a scanned cross-sectional image. According to the utility model, the welding penetration depth and appearance of each part of each welding product can be checked, the first-pass yield is greatly improved, the misjudgment rate of CCD (Charge Coupled Device) visual software and manpower is reduced, and the laser welding effects of a battery cover plate and an adapter piece or a tab, peripheral welding, a sealing nail and the like are effectively judged.

Description

Technical Field

[0001] The utility model relates to the technical field of laser welding, in particular to an online detection system for laser welding penetration. Background Art

[0002] As an indispensable energy source in today's world, lithium batteries have the characteristics of high voltage, light weight and high energy density, and can be charged quickly. They are applied to various fields of society, such as automobiles, mobile phones, computers, etc. In recent years, with the rapid development of electric vehicles, power tools, and model aircraft, higher requirements have been put forward for lithium-ion batteries, requiring the battery structure to be stable, consistent, safe and reliable, so it is urgent to continuously improve the materials, processes, equipment, and testing methods of lithium-ion batteries.

[0003] At present, when laser welding inspection is carried out on lithium batteries, it is only judged by CCD visual inspection software after welding. Generally, the laser welding area is captured in the visual image, image extraction is performed, and the size of the explosion point area is calculated using the built-in image algorithm. However, the welding condition is not just about the appearance, but mainly depends on the actual welding depth and welding strength. Judging the welding result only by the explosion point area is relatively simple, and it is impossible to know the internal welding condition of the lithium battery, that is, the effective melting depth of the cover plate and the adapter or the cover plate and the pole ear. Therefore, the first inspection will be carried out before the start of each day. Generally, destructive means such as cutting the welding point for metallographic analysis are used to check the internal condition. Only a small part of the products can be sampled for disassembly, and the disassembled batteries can only be scrapped, causing unnecessary waste. Therefore, there is a certain misjudgment when judging the welding effect only by the size of the explosion point area detected by CCD appearance. It is impossible to know the actual internal welding condition, which may cause misjudgment and lead to a low first-time pass rate. Utility Model Content

[0004] In order to solve the technical problems existing in the background technology, the utility model proposes an online detection system for laser welding penetration.

[0005] The utility model provides an online detection system for laser welding penetration, which comprises a spectrum analyzer, an optical lens group, a first detection sensor, and a reflector. The first detection sensor emits laser to the optical lens group, and the optical lens group divides the laser into two beams, one beam of laser is emitted to the welding seam of an object to be welded as signal light, and the other beam of laser is emitted to the reflector as reference light. The signal light and the reference light are reflected and return to the spectrum analyzer. When the lengths of the signal light and the reference light are consistent, interference occurs to form an interference spectrum. The interference spectrum is analyzed by the spectrum analyzer to obtain a scanned tomographic image, and a real-time penetration curve is drawn.

[0006] As a further optimized solution of the utility model, the first detection sensor includes a light source and a spectral interferometer.

[0007] As a further optimized solution of the utility model, it also includes a welding head system, a high-speed scanning system, and a second detection sensor. The high-speed scanning system and the second detection sensor are both installed on the welding head system. The second detection sensor transmits a detection laser to the high-speed scanning system. The detection laser enters the welding head system through a spectrometer in the high-speed scanning system. The detection laser and the welding laser are synchronously emitted to the object to be welded, directly measuring the laser processing position and the surrounding surface, obtaining a three-dimensional profile of the weld, and detecting the welding penetration and the post-weld morphology in real time.

[0008] As a further optimized solution of the utility model, the high-speed scanning system has an independent swing motor and laser mirror module inside to control the synchronous operation of the detection laser and the welding laser trajectory.

[0009] As a further optimized solution of the utility model, the welding head system includes a welding laser reflection source, a laser receiver, an optical lens and a CCD positioning chip.

[0010] As a further optimized solution of the utility model, the high-speed scanning system can enable the detection light source to scan and detect the penetration depth and width, the distance before welding, and the scanning contour of the post-weld morphology at a set frequency.

[0011] As a further optimized solution of the utility model, an optical lens and a beam splitter connected to the motor are provided in the optical lens assembly.

[0012] The laser welding penetration online detection system proposed by the utility model has the following beneficial effects:

[0013] The utility model divides the detection laser into signal light and reference light, and the signal light and the reference light are reflected back into the spectrum analyzer to interfere with each other to form an interference spectrum. The interference spectrum is analyzed by the spectrum analyzer to obtain a scanned tomographic image so as to draw a real-time penetration curve. In combination with the transmission of the detection laser of the second detection sensor by the high-speed scanning system, the detection laser emitted by the second detection sensor can be synchronously irradiated on the surface of the object to be welded with the welding laser of the welding head system, so that the welding penetration and morphology appearance of each welding product can be checked, the welding pass rate is greatly improved, the misjudgment rate of CCD visual software and manual work is reduced, and the laser welding effects of the battery cover and the adapter or the tab, the peripheral welding, the sealing nail, etc. are effectively judged.

[0014] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the detection principle of welding penetration of the utility model;

[0016] Figure 2 It is a schematic diagram of the detection principle of welding appearance of the utility model.

[0017] Description of the drawings: 1. Welding head system; 2. High-speed scanning system; 3. Second detection sensor; 4. Object to be welded; 5. Spectrum analyzer; 6. Optical lens group; 7. First detection sensor; 8. Reflector. DETAILED DESCRIPTION

[0018] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0019] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0020] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0021] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0023] See also Figure 1 and Figure 2 A laser welding penetration online detection system includes a spectrum analyzer 5, an optical lens group 6, a first detection sensor 7, and a reflector 8. The first detection sensor 7 emits laser light to the optical lens group 6, and the optical lens group 6 divides the laser light into two beams. One beam of laser light is emitted to the weld seam of the object to be welded 4 as signal light, and the other beam of laser light is emitted to the reflector 8 as reference light. The signal light and the reference light are reflected back to the spectrum analyzer 5. When the lengths of the signal light and the reference light are consistent, interference occurs to form an interference spectrum. The interference spectrum is analyzed by the spectrum analyzer 5 to obtain a scanned tomographic image and draw a real-time penetration curve.

[0024] The first detection sensor 7 includes a light source and a spectral interferometer, and has a function of analyzing the interference spectrum between the signal light and the reference light;

[0025] The sample light signal reflected by the object to be welded 4 and the reference light signal reflected by the reflector 8 are superimposed on each other. The higher the optical path length difference between the two light beams, the greater the modulation frequency generated on the interference spectrum. Therefore, by analyzing the spectrum of the reflection wave map by the spectrum analyzer 5, the distance to each surface point where reflection occurs in the imaging area can be measured. These light signals can be processed by a computer to obtain a scanned tomographic image, and then a real-time penetration curve can be drawn through processing. A high-resolution three-dimensional image can also be drawn through the morphology of the cross section of the reflective surface or the translucent surface.

[0026] Specifically, it also includes a welding head system 1, a high-speed scanning system 2, and a second detection sensor 3. The high-speed scanning system 2 and the second detection sensor 3 are both installed on the welding head system 1. The second detection sensor 3 emits a detection laser to the high-speed scanning system 2. The detection laser enters the welding head system 1 through a spectroscope in the high-speed scanning system 2. The detection laser and the welding laser are synchronously emitted to the object to be welded 4, directly measuring the laser processing position and the surrounding surface, obtaining a three-dimensional profile of the weld, and detecting the welding penetration and the post-weld morphology in real time;

[0027] Furthermore, the high-speed scanning system 2 has an independent swing motor and laser mirror module inside, which controls the detection laser and the welding laser to run synchronously;

[0028] During the laser welding process, the detection laser is swung at high speed in the high-speed scanning system 2, and the spectrum is fed back in real time before, during and after the welding laser, and the pre-welding height, welding penetration and post-welding height morphology are formed through analysis;

[0029] Further, the welding head system 1 includes a welding laser reflection source, a laser receiver, an optical lens and a CCD positioning chip;

[0030] Furthermore, the high-speed scanning system 2 can enable the detection light source to scan and detect the penetration depth and width, the distance before welding, and the scanning contour of the post-weld morphology at a set frequency;

[0031] Specifically, the optical lens assembly 6 is provided with an optical lens and a beam splitter connected to the motor;

[0032] When implementing laser welding detection, first move the welding laser head to the processing focus, the first detection sensor 7 emits a detection light source, which is divided into two laser beams by the beam splitter in the optical lens group 6. One laser beam is synchronously or asynchronously used as a detection laser in the welding head system 1, and the other laser beam is reflected by the reflector 8 as a reference light. The detection laser and the reference light are superimposed on each other to interfere. The higher the optical path difference between the two beams, the greater the modulation frequency generated on the interference spectrum. By analyzing the spectrum of the reflection wave diagram, the distance to the surface point where the welding point generates reflection can be measured, thereby determining the height of the initial point position of the welding penetration, which is also the starting welding focus position;

[0033] During the welding process, the detection system scans the working surface at a speed of 7000-25000 measurement points per second. The scanning directly covers the unwelded joint surface, the keyhole of the molten pool and the cooled seam. It can feedback the detection position in real time and with high precision. The detection position is fed back to the software to form countless penetration height points, which are connected into a curve with the maximum penetration depth point to form a welding penetration curve. The effective penetration depth of each point can be visually viewed. By setting the quality acceptance range in the formed penetration curve, the quality of the weld can be directly judged.

[0034] At the same time, the depth of penetration of the molten pool is determined by the depth profile of the molten pool along the welding direction, thereby obtaining the maximum penetration depth of the molten pool. In addition, the surface profile of the cooling weld can be scanned and measured, and the surface forming quality of the weld can be analyzed. By comparing the current weld with the reference weld, the system can determine the deviation and detect the fault, which is then displayed as an abnormal "NOK" signal, thereby judging the quality of the welded product in real time;

[0035] In summary, the welding depth of the connecting piece or the lug cover is more important than the appearance. Therefore, it is more reliable to change the evaluation standard from the explosion point area to the effective welding depth. However, the effective welding depth cannot be known from the CCD image. Now, the traditional laser welding detection device is added with the depth detection system to effectively control each welding product.

[0036] The laser welding penetration online detection system proposed by the utility model divides the detection laser into signal light and reference light. The signal light and the reference light are reflected back to the spectrum analyzer 5 to interfere with each other to form an interference spectrum. The interference spectrum is analyzed by the spectrum analyzer 5 to obtain a scanned tomographic image so as to draw a real-time penetration curve. Combined with the conduction of the detection laser of the second detection sensor 3 by the high-speed scanning system 2, the detection laser emitted by the second detection sensor 3 can be synchronously irradiated on the surface of the object to be welded 4 with the welding laser of the welding head system 1, so that the welding penetration and morphology of each welding product can be checked, which greatly improves the first-time qualified rate of welding, reduces the misjudgment rate of CCD visual software and manual work, and effectively judges the laser welding effects of battery cover and adapter or tab, peripheral welding, sealing nails, etc.

[0037] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A laser welding penetration online detection system, characterized in that: The invention comprises a spectrum analyzer, an optical lens group, a first detection sensor, and a reflector. The first detection sensor emits laser to the optical lens group, and the optical lens group divides the laser into two beams. One beam of laser is emitted to the weld seam of the object to be welded as signal light, and the other beam of laser is emitted to the reflector as reference light. The signal light and the reference light are reflected back to the spectrum analyzer. When the lengths of the signal light and the reference light are consistent, interference occurs to form an interference spectrum. The interference spectrum is analyzed by the spectrum analyzer to obtain a scanned tomographic image and draw a real-time penetration curve.

2. The laser welding penetration online detection system according to claim 1, characterized in that: The first detection sensor includes a light source and a spectral interferometer.

3. The laser welding penetration online detection system according to claim 1, characterized in that: It also includes a welding head system, a high-speed scanning system, and a second detection sensor. The high-speed scanning system and the second detection sensor are both installed on the welding head system. The second detection sensor transmits a detection laser to the high-speed scanning system. The detection laser enters the welding head system through a spectrometer in the high-speed scanning system. The detection laser and the welding laser are synchronously emitted to the object to be welded, directly measuring the laser processing position and the surrounding surface, obtaining a three-dimensional profile of the weld, and detecting the welding penetration and post-weld morphology in real time.

4. The laser welding penetration online detection system according to claim 3 is characterized in that: The high-speed scanning system has an independent swing motor and laser mirror module inside to control the synchronous operation of the detection laser and the welding laser trajectory.

5. The laser welding penetration online detection system according to claim 3 is characterized in that: The welding head system includes a welding laser reflection source, a laser receiver, an optical lens and a CCD positioning chip.

6. The laser welding penetration online detection system according to claim 3, characterized in that: The high-speed scanning system enables the detection light source to scan and detect the penetration depth and width, the distance before welding, and the scanning contour of the morphology after welding at a set frequency.

7. The laser welding penetration online detection system according to claim 1, characterized in that: An optical lens and a beam splitter connected to the motor are arranged in the optical lens assembly.

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