CN109175820B - A device for all-round direct observation of the shape of small holes in deep penetration welding of metal materials - Google Patents

Abstract

The invention provides a device for omnibearing and direct observation of the appearance of a small hole in metal material deep-fusion welding, which comprises a welding head, a composite test piece positioned below the welding head, and an image shooting part for observing the appearance of the small hole; the welding head is a welding head which can use laser or electron beams; the composite test piece comprises an upper metal test piece and a lower GG17 test piece, the top surface of the whole composite test piece, namely the top surface of the metal test piece, is a plane, the bottom surface of the metal test piece and the top surface of the GG17 test piece are both smooth joint surfaces, and the joint surfaces of the metal test piece and the GG17 test piece and the top surface of the composite test piece form an n-degree included angle, wherein n is more than 0 degree and less than 90 degrees; the image capturing means comprises a camera. The device provided by the invention can be used for omnibearing direct observation of the appearance of the small hole in metal material deep-melting welding, has no observation dead angle, and provides more accurate small hole shape for the research of small hole behavior and an energy absorption mechanism in the small hole.

Description

A device for all-round direct observation of the shape of small holes in deep penetration welding of metal materials

technical field

The invention relates to the field of deep-penetration welding, in particular to a device for direct observation of the shape of small holes in deep-penetration welding of metal materials in all directions.

Background technique

As a high-quality and efficient welding method, deep penetration welding (including laser, electron beam, etc.) has the advantages of fast welding speed, large weld aspect ratio, small heat-affected zone and welding deformation, etc. , rail transit, automobile, electronics industry and other military and civil major projects have been more and more widely used, especially in the lightweight of transportation vehicles (thin-walled components and aluminum, magnesium alloys and other lightweight materials welding) playing an increasingly important role.

(1) Current status of small hole observation technology

The essential feature of deep penetration welding (including laser, electron beam, etc.) is the existence of keyholes, that is, when a focused laser or electron beam with high power density irradiates the workpiece material, the workpiece material absorbs the energy of the laser or electron beam to produce melting, The gasification, in turn, under the action of the expansion pressure of the gasification, dislodges the molten material to create small pores. The formation of pinholes completely changes how energy is coupled with materials, such as lasers or electron beams. Before the small hole is formed, the energy of the laser or electron beam can only be absorbed by the surface of the workpiece, and then transmitted to the inside of the workpiece through heat conduction. The welding mode at this time is conduction welding; after the small hole is formed, the laser or electron beam can enter the inside of the small hole, Its energy is directly absorbed inside the workpiece, enabling deep penetration welding. Therefore, the formation and maintenance of small holes are the preconditions for the realization of deep penetration welding such as laser or electron beam, and the determination of the shape of the small holes has also become the research on the energy coupling mechanism of deep penetration welding (including laser, electron beam, etc.) hole effect) and the key to deep penetration welding mechanism.

However, in the process of deep penetration welding of metal materials, the small holes are wrapped in the opaque metal material, which is difficult to observe directly. For this reason, many scholars at home and abroad have been looking for ways to observe small holes for many years, and have made many useful attempts. Japan's Arata et al. took the lead in using transparent glass materials to directly observe the small holes of laser deep penetration welding from the side through high-speed photography. Since it uses ordinary sodium glass, the difference between the melting temperature and the vaporization temperature is very small, so it is difficult to distinguish the small hole from other high-temperature radiation areas. In addition, the used laser power (100 watts) is too small, and the welding speed (1mm/s) Too low, no clear pinhole shape can be observed. For opaque metal materials, Semak, Mohanty and Miyamato et al. used high-speed photography to observe the shape of small holes and molten pools on the surface of the workpiece during laser deep penetration welding from the upper part of the workpiece. The research team of Arata and Matsunawa used X-ray penetration imaging high-speed photography to observe the shape of the small hole in the laser deep penetration welding metal from the side, but the effect was not ideal, because the contrast of the X-ray photo was very small, and the shape of the small hole was not clear enough. Difficult to use for further quantitative analysis studies. In addition to using X-ray penetration imaging to observe the shape of the molten pool during laser deep penetration welding of metals from the side, Wang et al. also set up two high-speed cameras on the top and bottom of the workpiece to observe the shape of the small holes on the surface and bottom of the workpiece. , but the shape of the small hole inside the workpiece cannot be observed.

The applicant has also made some beneficial attempts on the direct observation of small holes in the process of laser deep penetration welding, and has continuously improved the observation method. Similar to the idea of Arata et al., the applicant also initially tried to use transparent materials to directly observe the small holes of laser deep penetration welding. The applicant has found a transparent material, GG17 glass, which can be well applied to simulate the laser deep penetration welding test, replacing the common soda glass used by Arata et al. It has good thermal shock resistance and is not easy to burst during the welding process, which can avoid the collapse or penetration of the small holes in laser deep penetration welding, and ensure that the small holes are complete and not distorted. feasible. Using this transparent specimen material, through high-speed photography (see Figure 1), the shape of the small hole during laser deep penetration welding was completely and clearly observed. Subsequently, in order to directly observe the shape of the small holes during laser deep penetration welding of metal materials, the applicant improved the experimental device shown in Figure 1, and proposed and adopted a multi-layer aluminum film (the so-called "sandwich") sandwiched between two pieces of GG17 glass. ” method, see Figure 2), the method of focusing the laser directly incident on the upper part of the aluminum film and moving along the aluminum film (the joint surface of the GG17 and the aluminum film is parallel to the welding direction, and the welding direction is in the horizontal plane) to simulate the laser deep penetration welding In the metal material process, the shape of the small hole was successfully observed from the side through the GG17 glass. However, this method has a significant disadvantage: the metal film layer used for welding is a loose structure, which is very different from the actual situation of the dense workpiece used in welding, because the loose multi-layer aluminum film is difficult for the laser depth. The effect of heat transfer, mass transfer, and laser energy absorption and transmission process during fusion welding is very different from the dense aluminum alloy materials used in engineering practice. The actual situation of the material is very different. Use such a small hole to theoretically study the small hole effect, especially to calculate the laser power density distribution of the multiple reflection absorption (Fresnel absorption) of the laser passing through the hole wall and the inverse bremsstrahlung absorption of the plasma in the hole. The calculation results It's hard to believe.

In order to overcome the shortcomings of the above-mentioned "sandwich" simulation welding method, the applicant has further improved the method (see Figure 3), using a double-layer composite workpiece (one half is a dense aluminum alloy widely used in engineering practice, and the other half is transparent GG17 glass) to replace the workpiece with the "sandwich" structure, through the method of high-speed photography, using the difference in the luminous intensity of the GG17 glass vapor and the metal plasma, through the transparent glass material, the small size of the laser deep penetration welding aluminum alloy is directly observed from the side. Hole, molten pool shape. This improved "sandwich" method was quickly applied by domestic researchers. However, using the experimental devices shown in Figures 1 to 3 can only directly observe the shape of the small holes in the laser deep penetration welding of aluminum alloys from the side through the transparent glass material, and cannot realize the omnidirectional observation of the small holes.

In summary, it can be found that the existing small hole observation methods can only observe the shape of the small hole during laser deep penetration welding from the top surface, bottom surface or side surface of the workpiece, that is, only the top surface, bottom surface or the moving section of the laser beam axis can be obtained. The shape of the small hole inside (that is, the symmetrical section, which is also the bonding surface of the metal and the GG17), and the real three-dimensional small hole shape cannot be obtained.

(2) Current status of plasma observation technology

In the process of deep penetration welding (including laser, electron beam, etc.), after the formation of the small hole, under the action of high-power density focused laser or electron beam, the metal vapor in the hole is ionized to form plasma. The plasma absorbs the laser energy through anti-bremsstrahlung, and then transfers the absorbed energy to the workpiece material by means of convection, heat conduction and thermal radiation. The anti-bremsstrahlung absorption of the laser by the plasma is another important aspect of the pinhole effect. Plasma with different densities, volumes and states will affect the passing laser beam to different degrees. Due to the appearance of plasma, there are two absorption mechanisms of laser energy, Fresnel absorption and anti-bremsstrahlung absorption. To study the anti-bremsstrahlung absorption of laser by plasma in depth, it is necessary to have all the information of the plasma generated during the laser welding process. The plasma generated by the laser beam acting on the processed workpiece is called photoplasma, which can be divided into the plasma outside the hole and the plasma inside the hole according to the different positions of the workpiece. Due to the convenience of observation of the plasma outside the hole, there are many researches at home and abroad. However, the plasma in the hole is difficult to observe directly because it is wrapped in an opaque metal material. Scholars from various countries have been looking for ways to observe it experimentally. Miyamoto et al. studied the radiation spectrum of the plasma in the small hole by arranging a series of photodiodes at an angle on the upper part of the workpiece, as shown in Figure 4. However, due to the bending of the small hole in the laser deep penetration welding process, there is a dead angle for observation, so it is difficult to obtain all the information of the plasma radiation spectrum in the small hole by this method. Based on the "sandwich" scheme, Zhang Yi et al. used a spectroscope to directly observe the plasma in the hole, and calculated its temperature and density. The results are also unconvincing due to the inherent shortcomings of the aforementioned "sandwich" approach. The applicant once proposed a method for directly observing the plasma in the hole (see Figure 5), the GG17 glass used in this method is amorphous, and its spectral lines are continuous spectral lines without any identifiable characteristic spectral lines (see Figure 9). (a)), and there is no selective absorption of the radiation spectral band of the alloying elements in the aluminum alloy. Through this glass material, the characteristic radiation spectral lines of the alloying elements in the aluminum alloy during the laser deep penetration welding process can be clearly observed. (See Figure 9(b)), so it is completely feasible to use a spectrometer to observe and analyze the metal plasma radiation spectrum during laser deep penetration welding of aluminum alloys through GG17 glass. This method is based on the small hole observation device shown in Fig. 3, replaces the high-speed camera with a multi-channel spectrometer, and directly detects the plasma radiation spectrum in the hole during laser deep penetration welding of aluminum alloys through GG17 transparent glass material from the side. However, this method can only observe the radiation spectrum information in the symmetry plane (that is, the contact surface between the aluminum alloy specimen and the GG17 glass specimen), and cannot directly observe the full distribution information of the plasma radiation spectrum in the cross-section of the small hole at different depths. To obtain all the distribution information of the plasma in the small hole, it is necessary to accurately detect the plasma spectrum in the small hole in all directions.

To sum up, in the prior art, there is neither a device or method that can directly observe the morphology of the metal material deep penetration welding hole in all directions, nor is there a device and method that can directly observe the inside of the metal material deep penetration welding hole. There is no device and method for all-round direct observation of plasma distribution, and there is also no composite specimen that can be used for all-round direct observation of small holes in deep penetration welding of metal materials.

SUMMARY OF THE INVENTION

Therefore, the present invention first provides a composite test piece for direct observation of metal material deep penetration welding small holes in all directions, the composite test piece includes an upper metal test piece and a lower GG17 test piece, and the top of the entire composite test piece is The top surface of the metal test piece is a plane, the bottom surface of the metal test piece and the top surface of the GG17 test piece are smooth joint surfaces, and the joint surface between the metal test piece and the GG17 test piece and the top surface of the composite test piece are the same. There is an included angle of n degrees, and 0°<n<90°.

In a specific embodiment, 1°≤n≤60°, preferably 2°≤n≤45°, more preferably 5°≤n≤30°.

In a specific embodiment, the bottom surface of the composite test piece, that is, the bottom surface of the GG17 test piece is a plane, and the bottom surface of the composite test piece is parallel to the top surface of the composite test piece.

In a specific embodiment, the composite test piece is in the shape of a cuboid or a cube as a whole.

In a specific embodiment, the metal test piece is a triangular prism structure with a top surface, an inclined bottom surface and one vertical side surface, all of which are rectangular, and two opposite vertical sides are right-angled triangles.

In a specific embodiment, the GG17 test piece has a triangular prism structure, or the GG17 test piece has an inclined top surface, a bottom surface, and two opposite vertical sides are rectangular, and the other two opposite The vertical sides of the GG17 are all right-angled trapezoid quadrangular prism structures; and preferably, the GG17 specimens are quadrangular prism structures.

In a specific embodiment, the metal test piece is an aluminum alloy test piece.

The present invention also provides a corresponding device for observing small holes in deep penetration welding, which includes the composite test piece described above, and a reflecting mirror arranged under the composite test piece and used to change the direction of light transmission.

In addition, the present invention provides a device for all-round direct observation of the shape of a small hole in deep penetration welding of metal materials, the device includes a welding head, a composite test piece located under the welding head, and an image capture for observing the shape of the small hole The welding head is a welding head that can use laser or electron beam; the composite test piece includes an upper metal test piece and a lower GG17 test piece, and the top surface of the entire composite test piece is the top of the metal test piece. The surface is a plane, the bottom surface of the metal specimen and the top surface of the GG17 specimen are both smooth joint surfaces, and the joint surface of the metal specimen and the GG17 specimen and the top surface of the composite specimen are at an angle of n degrees. and 0°<n<90°; the image capturing component includes a camera, and the image capturing component can continuously capture the projection of the cross-sectional shape of the small hole on the joint surface of the composite test piece on the horizontal plane from bottom to top.

In a specific embodiment, the image capturing component is integrally arranged on a translation table.

In a specific embodiment, the welding head is a laser welding head, and includes a laser beam, a compressed air inlet, a laser welding nozzle and a GaAs focusing lens; the image capturing component further includes a reflector and a filter.

In a specific embodiment, the device further comprises an argon gas nozzle (11) for preventing metal oxidation and enhancing heat dissipation on the surface of the welded workpiece.

In addition, the present invention also provides a method for all-round direct observation of the shape of a small hole in deep penetration welding of metal materials. The method includes using a composite test piece, and the composite test piece includes a metal test piece and The top surface of the entire composite test piece, that is, the top surface of the metal test piece is flat, and the bottom surface of the metal test piece and the top surface of the GG17 test piece are both smooth joint surfaces. An angle of n degrees is formed between the joint surface of the test piece and the top surface of the composite test piece, and 0°<n<90°; the method includes the following steps:

Step A, the composite test piece is fixedly arranged so that the top surface of the composite test piece is in a horizontal plane, and a welding head is arranged above the composite test piece, and the welding head is a welding head that can use a laser or an electron beam, And the incident direction of the laser or electron beam is vertically downward; and an image capturing part for observing the shape of the pinhole is provided, the image capturing part includes a camera, and the image capturing part can continuously capture the image from bottom to top. The projection of the cross-sectional shape of the small hole on the joint surface of the composite specimen on the horizontal plane;

Step B. Define the intersection line of the joint surface or the extension surface of the joint surface and the top surface of the composite test piece as L, start the welding head to perform deep penetration welding on the composite test piece, and the welding direction is the translation direction of the welding head during the welding process. is the direction perpendicular to the intersection line L in the horizontal plane.

In a specific embodiment, the image capturing component is integrally arranged on a translation table, and the displacement table moves synchronously with the welding direction and welding speed, so as to capture the small holes on the joint surface in time Projected image in the horizontal plane.

In addition, the present invention also provides a device for all-round direct observation of plasma in a small hole of metal material deep penetration welding, the device includes a welding head, a composite test piece located under the welding head, and a device for observing plasma in the small hole The spectroscopic signal detection component of the physical condition; the welding head is a welding head that can use laser or electron beam; the composite test piece includes a metal test piece on the top and a GG17 test piece below, and the top surface of the entire composite test piece is That is, the top surface of the metal test piece is a plane, the bottom surface of the metal test piece and the top surface of the GG17 test piece are smooth joint surfaces, and the joint surface between the metal test piece and the GG17 test piece and the top surface of the composite test piece are The included angle is n degrees, and 0°<n<90°; the spectral signal detection component includes an optical fiber and a spectrometer.

In a specific embodiment, the spectral signal detection component further includes a reflector and an optical fiber fixing plate.

In a specific embodiment, the spectral signal detection component is integrally arranged on a translation table.

In a specific embodiment, the device further includes an image capturing component for direct observation of the shape of the small hole in all directions, the image capturing component includes a camera, and the image capturing component can be continuous from bottom to top The projection of the cross-sectional shape of the small hole on the joint surface of the composite test piece on the horizontal plane is photographed.

In a specific implementation manner, the image capturing component is integrally arranged on a translation table, and preferably the image capturing component further includes a reflector and a filter.

In addition, the present invention also provides a method for all-round direct observation of plasma in a small hole of deep penetration welding of metal materials, the method includes using a composite test piece, and the composite test piece includes a metal test piece on the and the GG17 specimen below, and the top surface of the entire composite specimen, that is, the top surface of the metal specimen, is a plane, and the bottom surface of the metal specimen and the top surface of the GG17 specimen are both smooth joint surfaces. There is an included angle of n degrees between the joint surface of the GG17 specimen and the top surface of the composite specimen, and 0°<n<90°; the method includes the following steps:

Step A, the composite test piece is fixedly arranged so that the top surface of the composite test piece is in a horizontal plane, and a welding head is arranged above the composite test piece, and the welding head is a welding head that can use a laser or an electron beam, and the incident direction of the laser or electron beam is vertically downward; and a spectral signal detection component for observing the plasma condition in the small hole is provided, and the spectral signal detection component includes an optical fiber and a spectrometer;

Step B. Define the intersection line of the joint surface or the extension surface of the joint surface and the top surface of the composite test piece as L, start the welding head to perform deep penetration welding on the composite test piece, and the welding direction is the translation direction of the welding head during the welding process. is the direction perpendicular to the intersection line L in the horizontal plane.

In a specific embodiment, the spectral signal detection component further includes a reflector and an optical fiber fixing plate; preferably, the spectral signal detection component is integrally disposed on a translational displacement table, and the displacement table follows the welding process. The direction and welding speed are moved synchronously in order to capture the spectral signal of the plasma in the small hole in time.

In a specific embodiment, it also includes using an image capturing component to be used in conjunction with the welding head and the composite test piece to directly observe the shape of the small hole in all directions, the image capturing component includes a camera, and the image capturing The component can continuously shoot the projection of the cross-sectional shape of the small hole on the joint surface of the composite test piece on the horizontal plane from bottom to top; specifically, you can first use the image shooting component, the welding head and the composite test piece to observe the shape of the small hole, and arrange the optical fibers reasonably. The position on the optical fiber fixing plate to ensure that the optical fiber can obtain the optical signal in the entire cross-section of the small hole, and then use the spectral signal detection component, the welding head and the composite specimen to observe the plasma in the small hole; or use the spectral signal detection component first , the welding head and the composite specimen to observe the plasma in the small hole, and then use the image capturing component, the welding head and the composite specimen to observe the shape of the small hole.

The present invention has at least the following beneficial effects:

1) The small hole observation experimental device provided by the present invention can clearly and accurately observe the cross-sectional profiles of real three-dimensional small holes at different depths, and there is no observation dead angle, so that the accuracy of subsequent reconstruction of small holes is higher, and it is more in line with the actual small hole. Pore shape, providing more precise pore shape for the study of pore behavior and the energy absorption mechanism in the pore.

2) The plasma observation device in the small hole provided by the present invention can clearly and accurately detect the plasma radiation spectrum information in the real three-dimensional small hole section at different depths, and combined with the reconstructed accurate three-dimensional small hole, the real three-dimensional small hole can be obtained. All the plasma radiation spectral information in the hole has no dead angle of observation, which is more in line with the actual situation, and provides accurate plasma parameters in the hole for the study of plasma anti-bremsstrahlung absorption.

Description of drawings

FIG. 1 is a structural diagram of a first deep penetration welding pinhole topography observation device in the prior art.

FIG. 2 is a structural diagram of a second type of deep penetration welding pinhole topography observation device in the prior art.

FIG. 3 is a structural diagram of a third type of deep penetration welding pinhole topography observation device in the prior art.

FIG. 4 is a structural diagram of a first type of deep penetration welding small hole plasma observation device in the prior art.

FIG. 5 is a structural diagram of a second type of plasma observation device in a small hole for deep penetration welding in the prior art, specifically including FIG. 5( a ) and FIG. 5( b ).

FIG. 6 is a structural diagram of an omnidirectional direct observation device for deep penetration welding pinhole morphology provided by the present invention.

FIG. 7 is a structural diagram of an all-round direct observation device for plasma in a small hole of deep penetration welding provided by the present invention.

FIG. 8 is a schematic structural diagram of the composite test piece of the present invention that has formed small holes in the deep penetration welding process.

In Figures 6 to 8 of the present invention: 1-laser beam, 2-compressed air inlet, 3-laser welding nozzle, 4-metal specimen, 5-GG17 specimen, 6-filter, 7, camera, 8-reflector, 9-pinhole, 10-welding direction, 11-argon gas nozzle, 12-GaAs focusing lens, 13-fiber fixing plate, 14-fiber, 15-spectroscope, 88-joint surface.

FIG. 9 is a spectral line diagram of GG17 glass and aluminum alloy provided by the prior art or the present invention, specifically including FIG. 9( a ) and FIG. 9( b ).

Detailed ways

As shown in FIG. 6 , the present invention provides a device for direct observation of the shape of small holes in deep penetration welding of metal materials in all directions. The welding head is a welding head that can use laser or electron beam; the composite test piece includes a metal test piece 4 above and a GG17 test piece 5 below, and the top surface of the entire composite test piece is That is, the top surface of the metal test piece is a plane, the bottom surface of the metal test piece and the top surface of the GG17 test piece are smooth joint surfaces, and the joint surface 88 of the metal test piece and the GG17 test piece and the top surface of the composite test piece are the same. There is an included angle of n degrees, and 0°<n<90°; the image capturing part includes a camera 7, and the image capturing part can continuously capture the small holes on the joint surface of the composite specimen from bottom to top The projection of the shape on the horizontal plane.

In a specific embodiment, the image capturing component is integrally arranged on a translation table.

In a specific embodiment, the welding head is a laser welding head, and includes a laser beam 1, a compressed air inlet 2, a laser welding nozzle 3 and a GaAs focusing lens 12; the image capturing component further includes a mirror 8 and filter 6.

In a specific embodiment, the device further includes an argon gas nozzle 11 for preventing metal oxidation and enhancing heat dissipation on the surface of the welded workpiece.

In a specific embodiment, 1°≤n≤60°, preferably 2°≤n≤45°, more preferably 5°≤n≤30°.

In a specific embodiment, the bottom surface of the composite test piece, that is, the bottom surface of the GG17 test piece is a plane, and the bottom surface of the composite test piece is parallel to the top surface of the composite test piece.

In a specific embodiment, the composite test piece is in the shape of a cuboid or a cube as a whole.

In a specific embodiment, the metal test piece is a triangular prism structure with a top surface, an inclined bottom surface and one vertical side surface, all of which are rectangular, and two opposite vertical sides are right-angled triangles.

In a specific embodiment, the GG17 test piece has a triangular prism structure, or the GG17 test piece has an inclined top surface, a bottom surface, and two opposite vertical sides are rectangular, and the other two opposite The vertical sides of the GG17 are all right-angled trapezoid quadrangular prism structures; and preferably, the GG17 specimens are quadrangular prism structures.

In a specific embodiment, the metal test piece is an aluminum alloy test piece.

Example 1

A technical solution for directly observing the cross-sectional profile shape of the small hole at different depths by using the device shown in Figure 6.

As shown in Figure 6, a new device for direct observation of the shape of small holes in deep penetration welding of metal materials (laser, electron beam, etc.) includes a laser beam 1, a compressed air inlet 2, a laser welding nozzle 3, an argon Laser welding head composed of gas nozzle 11 and GaAs focusing lens 12 , composite test piece composed of metal test piece 4 and GG17 test piece 5 , and image capturing component composed of filter 6 , camera 7 and reflector 8 .

The experimental principle observed in Figure 6: the present invention adopts a double-layer composite workpiece, that is, the upper part of the metal test piece 4 is a metal widely used in engineering practice, and the lower part of the GG17 test piece 5 is a transparent special glass with good thermal shock resistance GG17, the joint surface of the two is a small angled slope. Using the difference in the luminous intensity of GG17 glass vapor and metal plasma, the high-speed camera directly observes the small holes on the joint surface of the metal specimen and the GG17 glass specimen at different depths during deep penetration welding of the metal material from the lower part of the workpiece through the transparent glass material. molten pool shape. In the case of stable welding, by selecting the appropriate thickness of the filter 6, the high-speed camera can obtain a series of cross-sectional profiles of small holes and molten pools. ) imaging technology. On the basis of the layer-by-layer observation of the cross-sectional shape of the pinhole, the real three-dimensional pinhole shape can be obtained by reconstruction, which provides the accurate pinhole shape basis for the theoretical study of pinhole effect.

The diameter and depth of the small hole will vary depending on the welding power, welding speed, defocusing amount, and workpiece material, but the diameter of the small hole in laser deep penetration welding is usually less than 1mm. In the stable state of deep penetration welding of metal materials, this small hole always exists, and the plasma fills the entire inside of the small hole. That is to say, those skilled in the art in the prior art have already known that the small hole is an irregular curved small hole, which is generally curved in the height direction (vertical direction) and has a pointed tip facing downwards. , and the bending direction of the small hole is opposite to the welding direction, and the shape of the top surface of the small hole is reported to be circular, elliptical or water drop-shaped. And the height of the small hole and the shape of the small hole in the symmetrical section are known in the prior art. However, the cross-sectional shape of the small hole at each depth in the small hole is not clear in the prior art. When the small hole is reconstructed, the cross-sectional shape of the depth can only be described ideally as a circle, an ellipse, a water drop shape, etc. The shape of the top surface of the small hole is similar to the shape of the figure. Many scholars, including the inventor, believe that since the deep penetration welding of metals is a dynamic process, the cross-sectional shape inside the small hole may not be related to the shape of the top of the small hole. However, there is no device in the prior art that can directly observe the morphology of the small holes in deep penetration welding in all directions.

In the welding direction shown in FIG. 6 , the shape of the top surface of the small hole (where the radial dimension is the largest) is initially imaged, and finally the shape of the bottom of the small hole, that is, the shape of the tip portion is imaged. If the welding direction is opposite to the welding direction in FIG. 6 , the shape of the bottom of the small hole, that is, the shape of the tip of the small hole is initially imaged, and finally the shape of the top surface of the small hole is imaged.

In the present invention, the high-speed camera is the abbreviation of high-speed camera, that is, CCD. The high-speed camera shown in Fig. 6 is arranged on the side of the composite specimen, and the main purpose is to prevent the camera from being damaged by metal splashing during deep penetration welding. In the process of laser deep penetration welding, although the direction of laser irradiation can be in any direction, the most commonly used laser irradiation direction is generally vertical downward or slightly inclined. Therefore, the laser is selected to irradiate vertically downward.

Example 2

A technical solution for directly observing plasma information in cross-sections of small holes at different depths using the device shown in Figure 7.

As shown in Figure 7, a new device for direct observation of plasma in small holes for deep penetration welding of metal materials (laser, electron beam, etc.) includes a laser beam 1, a compressed air inlet 2, a laser welding nozzle 3, Laser welding head composed of argon gas nozzle 11, GaAs focusing lens 12, composite specimen composed of metal specimen 4 and GG17 specimen 5, and plasma composed of reflector 8, optical fiber fixing plate 13, optical fiber 14 and spectrometer 15 Bulk spectral signal detection components.

The experimental principle observed in Figure 7: the present invention adopts a double-layer composite workpiece, that is, the upper part of the metal test piece 4 is a metal widely used in engineering practice, the lower part of the GG17 test piece 5 is transparent GG17 glass, and the joint surface of the two is A bevel at a small angle. Through the reasonable arrangement of multiple optical fibers 14, the multi-channel spectrometer 15 is used to directly observe the cross-section of the small hole on the joint surface of the metal specimen and the GG17 glass specimen at different depths through the transparent glass material from the lower part of the workpiece. Plasma Radiation Spectral Information. In the case of stable welding, the multi-channel spectrometer 15 can continuously obtain plasma information in a series of small hole sections, that is, direct observation of slice-by-section sections, similar to CT (Computed Tomography) imaging technology commonly used in medicine. Combined with the real three-dimensional small hole shape obtained by layer-by-layer observation and reconstruction of the cross-sectional shape of the small hole in Example 1, all the spectral distribution information of plasma radiation in the real three-dimensional small hole can be obtained, which provides accurate information for the theoretical study of plasma inverse bremsstrahlung absorption. The plasma parameters in the hole.

In FIG. 7 of the present invention, because one optical fiber can only observe the distribution information of plasma in a certain area, in order to obtain complete plasma information in the small hole, it is necessary to arrange the positions of multiple optical fibers reasonably. The total area observed by the optical fiber is at least larger than the area of the top surface of the small hole (the top surface area of the small hole is the largest cross-sectional area of the entire small hole). For the specific arrangement plan, refer to the top surface of the small hole. In the prior art, the optical fiber is used to observe the longitudinal section information of the small hole, so it only involves the arrangement of the optical fiber in the one-dimensional direction (the central axis of the small hole), while the optical fiber in the present invention involves the two-dimensional direction (the small hole). A reasonable arrangement on the cross section).

Example 3

FIG. 8 is a schematic view of the structure of the composite test piece of the present invention in which the small holes 9 have been formed in the deep penetration welding process. Before deep penetration welding, the composite test piece described in the present invention does not contain pinholes. The composite test piece includes an upper metal test piece 4 and a lower GG17 test piece 5, and the top surface of the entire composite test piece, that is, the top surface of the metal test piece, is a plane, and the bottom surface of the metal test piece is the same as the top surface of the GG17 test piece. The surfaces are smooth joint surfaces, and the joint surface (88) of the metal test piece and the GG17 test piece and the top surface of the composite test piece form an included angle of n degrees, and 0°<n<90°.

In the process of preparing the composite test piece of the present invention (see Figure 8 for its structure), the joint surfaces of the metal test piece and the GG17 test piece are polished smooth, and then the two are fixed together with a clamp to form a composite test piece.

In the present invention, the value of n is, for example, 1°≤n≤60°, preferably 2°≤n≤45°, more preferably 5°≤n≤30°. The larger the angle n is, the closer it is to 90°, the greater the ratio of the height of the composite test piece to the length of the composite test piece in the welding direction. Under the same welding speed, the shape of the small holes on the joint surface changes. Therefore, if n is too large, the shooting speed and accuracy of the high-speed camera may not meet the requirements, which will affect the observation accuracy of small holes. The smaller the angle n is, the closer it is to 0°, the smaller the ratio of the height of the composite test piece to the length of the composite test piece in the welding direction, and at the same welding speed, the smaller the change in the shape of the small holes on the joint surface. Slow, so the smaller n is, the higher the shooting accuracy is. However, if n is too small, the length of the composite test piece (the length in the welding direction) may be too large.

In the present invention, if the metal test piece is in the shape of a quadrangular prism, the shape of the small hole at a depth from the top of the small hole cannot be photographed. Therefore, the metal test piece in the present invention is preferably in the shape of a triangular prism. In the present invention, it is preferable that the bottom surface of the composite test piece is parallel to the top surface of the composite test piece, so that the composite test piece can be fixed by the fixture and observed conveniently.

In the present invention, the lower part of the composite test piece adopts GG17 glass test piece. GG-17 is a kind of fireproof glass, specifically a kind of high borosilicate glass. High borosilicate glass has a very low coefficient of thermal expansion, high temperature resistance, and a 200-degree temperature change. The softening temperature and gasification temperature of GG17 glass are far away, and the thermal shock resistance is good, and it is not easy to burst during the welding process. The spectrum of GG17 glass will not affect and interfere with the observation of deep penetration welding of aluminum alloy, so it is the best glass for the research of deep penetration welding of aluminum alloy. However, if a more suitable lower specimen than GG17 glass is found or researched in the future, it can be used instead of the GG17 specimen in the present invention to obtain a composite specimen.

In addition, in the prior art represented by FIGS. 1 to 5 and the device of the present invention represented by FIGS. 6 to 7 , the purpose of the GaAs focusing lens is to focus the light emitted by the laser beam to form a smaller spot to concentrate energy. The main uses of the protective argon are: ① to isolate the air to avoid oxidation during the welding process of the test piece and affect the welding effect; ② to blow away the plasma formed in the upper part of the small hole, so as to avoid the plasma changing the laser path and affecting the welding heat input; ③ to strengthen the workpiece The surface dissipates heat and effectively reduces the deformation of the workpiece. The purpose of the shielding air, ie the compressed gas, is to avoid welding spatter from damaging the GaAs focusing lens. The purpose of the filter is to take pictures with suitable brightness, which can clearly distinguish the small hole part and the high temperature molten pool part. Obtain a photo of the pinhole cross-section with a clear image. The purpose of setting the displacement table in FIG. 5 is to keep the plasma observation equipment moving synchronously with the small hole formed in the deep penetration welding, and to capture the topography of the cross section of the small hole (on the joint surface) in time.

In the prior art devices represented in FIGS. 1 to 5 , the profiles of the cross-sections (ie, the bonding surfaces) of the small holes are directly photographed from the side, so that no reflector is required to change the direction of the light. In the device of the present invention represented by Figures 6 to 7, the projection of the cross-section of the small hole (that is, the joint surface) on the horizontal plane is taken from the bottom of the composite test piece, so as to avoid the molten metal splashed by high-speed cameras and other equipment. Therefore, in the present invention, a mirror needs to be used to observe the small holes of deep penetration welding. In addition, because the lower part of the composite specimen is transparent glass and the upper part is opaque metal, and the camera shoots from the bottom to the top, the high-speed camera in the present invention observes the small holes and the shape of the molten pool on the bonding surface. And what is directly observed is the projection of the shape on the horizontal plane.

In the device and the corresponding method shown in FIGS. 6 and 7 of the present invention, those skilled in the art can understand that the welding starts from the middle position of the intersection line L, and generally ends when the welding reaches the middle position of the opposite side of the intersection line L. welding; or welding in the opposite way. The speed for deep penetration welding of aluminum alloys is, for example, 1000 mm/min, although other faster or slower welding speeds are also possible.

It can be seen from FIGS. 1-7 that in the prior art, the welding direction line is parallel to or within the bonding surface, while in the present invention, the welding direction line and the bonding surface form an acute included angle.

Different from the prior art, the present invention achieves major breakthroughs in the following aspects.

1) Aiming at the existing small hole topography observation method, only the top surface, bottom surface of the workpiece or the small hole profile shape in the moving section of the laser beam axis (that is, the symmetrical section) can be observed, and the deficiency of the omnidirectional observation of the small hole cannot be realized. The present invention An experimental device for directly observing the cross-sectional profile shape of small holes at different depths through transparent materials is provided, which completely solves the problem of all-round observation of small holes in deep penetration welding of metal materials.

2) Aiming at the deficiency that the existing plasma observation method can only observe the plasma information in the hole outside the hole or in the moving section of the laser beam axis (that is, the symmetrical section), and cannot realize the omnidirectional observation of the plasma information in the small hole, the present invention An experimental device for directly observing the plasma information in the cross-section of the small hole at different depths is provided through a transparent material, which completely solves the problem of all-round observation of the plasma information in the small hole of the metal material deep penetration welding.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deductions and substitutions can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (10)

1. A device for direct observation of the shape of a small hole in deep penetration welding of a metal material in all directions, the device comprises a welding head, a composite test piece positioned below the welding head, and an image capturing component for observing the shape of the small hole; The welding head is a welding head capable of using laser or electron beam; The composite test piece includes an upper metal test piece (4) and a lower GG17 test piece (5), and the top surface of the entire composite test piece, that is, the top surface of the metal test piece, is a plane, and the bottom surface of the metal test piece is the same as the GG17 test piece. The top surfaces of the test pieces are all smooth joint surfaces, the joint surface (88) of the metal test piece and the GG17 test piece and the top surface of the composite test piece are at an angle of n degrees, and 0°<n<90° ; The image capturing component includes a camera (7), and the image capturing component can continuously capture the projection of the shape of the small hole on the joint surface of the composite test piece on the horizontal plane from bottom to top. 2 . The device according to claim 1 , wherein the image capturing component is integrally disposed on a translation table that can move. 3 . 3. The device according to claim 1, wherein the welding head is a laser welding head, and comprises a laser beam (1), a compressed air inlet (2), a laser welding nozzle (3) and a GaAs focusing lens (12) ); the image capturing component further includes a reflector (8) and a filter (6). 4. The device according to claim 1, characterized in that, the device further comprises an argon gas nozzle (11) for preventing metal oxidation and enhancing heat dissipation on the surface of the welded workpiece. 5. The device according to claim 1, wherein 5°≤n≤30°. 6 . The device according to claim 1 , wherein the bottom surface of the composite test piece, that is, the bottom surface of the GG17 test piece, is a plane, and the bottom surface of the composite test piece is parallel to the top surface of the composite test piece. 7 . 7 . The device according to claim 6 , wherein the composite test piece is in the shape of a cuboid or a cube as a whole. 8 . 8 . The device according to claim 7 , wherein the metal test piece is a rectangular prism with a top surface, an inclined bottom surface and a vertical side surface, and two opposite vertical sides are right-angled triangular prisms. 9 . shape structure. 9. The device according to claim 7, wherein the GG17 test piece is a triangular prismatic structure, or the GG17 test piece is a rectangle with an inclined top surface, a bottom surface and two opposite vertical sides. , while the other two opposite vertical sides are both right-angled trapezoid quadrangular prism structures. 10 . The device according to claim 1 , wherein the metal test piece is an aluminum alloy test piece. 11 .