CN116511712B - Diamond wire laser welding method and system - Google Patents

Diamond wire laser welding method and system Download PDF

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Publication number
CN116511712B
CN116511712B CN202310774589.XA CN202310774589A CN116511712B CN 116511712 B CN116511712 B CN 116511712B CN 202310774589 A CN202310774589 A CN 202310774589A CN 116511712 B CN116511712 B CN 116511712B
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welding
end parts
laser
crystal phase
real
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CN116511712A (en
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周禹
付明全
郭翔
薄千顷
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Sichuan Gaojing Solar Energy Technology Co ltd
Guangdong Jinwan Gaojing Solar Energy Technology Co ltd
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Sichuan Gaojing Solar Energy Technology Co ltd
Guangdong Jinwan Gaojing Solar Energy Technology Co ltd
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/20Bonding
    • B23K26/21Bonding by welding
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/0093Working by laser beam, e.g. welding, cutting or boring combined with mechanical machining or metal-working covered by other subclasses than B23K
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/60Preliminary treatment
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00Working by laser beam, e.g. welding, cutting or boring
    • B23K26/70Auxiliary operations or equipment
    • B23K26/702Auxiliary equipment
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23PMETAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P15/00Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00Articles made by soldering, welding or cutting
    • B23K2101/32Wires

Abstract

The invention provides a diamond wire laser welding method and a diamond wire laser welding system, which are used for positioning two ends of a broken wire so that the two ends are opposite; respectively shearing sections of the two end parts, and cleaning; the vision detection module is used for collecting pictures of the two end parts, detecting and calculating concentricity of the two end parts, and controlling the two end parts to automatically adjust positions so that the two end parts are concentric; aligning the target heating light spot of the laser generating module with a molten pool part formed by two end parts and a limited space around the two end parts, and starting laser heating welding; monitoring the real-time temperature and the real-time crystal phase of the molten pool part, adjusting the heating power of the laser generating module according to the real-time temperature, judging whether the matching degree of the real-time crystal phase image and the target crystal phase image is larger than a first threshold value, and stopping welding if the matching degree is larger than the first threshold value; and (5) polishing the welding line, and annealing to finish welding. The welding method has high automation degree, and utilizes the laser generating module to carry out laser welding, so that the heating is quick, the efficiency is high, and the accurate automatic welding is realized by judging the crystal phase image.

Description

Diamond wire laser welding method and system
Technical Field
The invention belongs to the technical field of diamond wire welding, and particularly relates to a diamond wire laser welding method and system.
Background
In the production process of monocrystalline silicon wafers, the silicon rods are subjected to acceleration and deceleration bidirectional cutting through a multi-wire diamond wire network, and in the cutting process, the phenomenon of diamond wire breakage often occurs due to reasons of machinery, electric appliances, process parameters, matching degree of an electric control software system and the like, and after the diamond wire is broken, workers need to weld or replace the diamond wire.
Current diamond wire welding methods include:
the resistance welding is a common welding mode in the current industry, and the welding process has the defects of low welding success rate, long welding time, poor welding appearance and low tensile strength, and greatly influences the production efficiency and yield of the silicon wafer.
Brazing refers to a welding method in which a brazing filler metal with a melting point lower than that of a weldment and the weldment are heated to a brazing filler metal melting temperature at the same time, and then gaps of solid workpieces are filled with liquid brazing filler metal to connect metals. The brazing deformation is small, the joint is smooth and attractive, but after the welding is finished, the tensile strength of the welding seam is relatively low, and the welding seam is easy to fracture again, so that the subsequent use is influenced.
No matter what welding mode, the whole-course manual welding operation is needed, the automation degree is low, the welding method is unreliable, the efficiency is low, and the tensile strength of the welding position is low.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a diamond wire laser welding method and system, which solve the defects that the high-quality and high-efficiency welding of the broken diamond wire cannot be realized in the prior art.
In a first aspect, the present invention provides a diamond wire laser welding method comprising:
positioning the two ends of the broken wire so that the two ends are opposite;
respectively shearing sections of the two end parts, and cleaning;
the vision detection module is used for collecting pictures of the two end parts, detecting and calculating concentricity of the two end parts, and controlling the two end parts to automatically adjust positions so that the two end parts are concentric;
aligning the target heating light spot of the laser generating module with a molten pool part formed by two end parts and a limited space around the two end parts, and starting laser heating welding;
monitoring the real-time temperature and the real-time crystal phase of the molten pool part, adjusting the heating power of the laser generating module according to the real-time temperature, judging whether the matching degree of the real-time crystal phase image and the target crystal phase image is larger than a first threshold value, and stopping welding if the matching degree is larger than the first threshold value;
and (5) polishing the welding line, and annealing to finish welding.
In some embodiments, when laser heating welding is performed, the target heating light spot is aligned to the molten pool part, so that metal is melted and gasified to form a heated hole, whether the vapor pressure in the heated hole is balanced with the surface tension and the gravity of the liquid metal or not is judged by utilizing the visual detection module, and if the vapor pressure in the heated hole is balanced with the surface tension and the gravity of the liquid metal, the target heating light spot is controlled to move along the welding directions of the two end parts, so that a welding seam is formed.
In some embodiments, the molten pool portion is monitored by a near infrared thermal imaging module, a near infrared image and a thermal imaging image are obtained, a switching duty ratio parameter of the laser generating module is determined according to the gray level of the near infrared image and the thermal distribution coefficient of the thermal imaging image, and heating power of the laser generating module is adjusted according to the switching duty ratio parameter.
In some embodiments, the welding period is divided into a plurality of stages, according to diamond wires of different materials, for each stage, a gray level constant of a corresponding near-infrared image and a thermal distribution coefficient constant of a thermal imaging image are determined, corresponding on-off duty ratio parameters are set, and the two ends of the broken wire are subjected to stage welding.
In some embodiments, the laser generating module is a picosecond laser generator, and the laser with the wavelength of 600 nm-700 nm is used for performing staged welding on two ends of the broken wire.
In some embodiments, for diamond wires of different materials and specifications, target crystal phase images are set respectively, the target crystal phase images are configured to select one diamond wire, target heating spots of a laser generating module are aligned to a part of the diamond wire, the balance between vapor pressure and the surface tension and gravity of liquid metal is achieved at the part, and after heating is completed along the radial direction, the obtained crystal phase images are acquired.
In some embodiments, the two ends of the broken wire are placed in a V-shapeThe magnetic platform of the groove is used for pressing the broken wire from top to bottom by using a pressing block, the end part of the broken wire extends out of the magnetic platform for setting an extension distance, and the pressure F applied to the pressing block by an air cylinder<[78500*N/(cos a/2)]-(m 1 +m) g, wherein the mass of the briquette is m, and the mass of the broken wire contacted with the unit area of the magnetic platform is m 1 The included angle of the V-shaped groove in the magnetic platform is a, and the number N of diamond particles is on the contact surface of the broken wire and the magnetic platform.
In some embodiments, when the two end portions are subjected to section shearing, a double-edged ring cutter is adopted, and shearing force is simultaneously applied inwards along the radial direction of a certain section of the broken line, so that a welding section perpendicular to the axial center line of the broken line is formed at the end portions.
In some embodiments, when the welding seam is polished, the welding seam formed on the molten pool part is wrapped by a polishing mechanism, silicon carbide is embedded on the contact surface of the polishing mechanism and the welding seam, and the polishing mechanism is controlled to perform high-hertz micro-amplitude cross-frequency vibration, so that surface bubbles and impurities in the welding seam are eliminated.
In a second aspect, the present invention provides a welding system applied to the above-mentioned diamond wire laser welding method, including:
the positioning mechanism is used for positioning the end parts of the broken wire so that the two end parts are opposite;
the shearing mechanism is used for shearing the sections of the two end parts respectively;
the cleaning mechanism is used for cleaning the two end parts respectively;
the visual detection module is used for collecting pictures of the two end parts, detecting and calculating concentricity of the two end parts, and controlling the positioning mechanism to drive the two end parts to automatically adjust positions so that the two end parts are concentric;
the laser generating module is used for generating target heating light spots aligned with a molten pool part formed by two end parts and a limited space around the two end parts and carrying out laser heating welding;
the detection module is used for monitoring the real-time temperature and the real-time crystal phase of the molten pool part, adjusting the heating power of the laser generation module according to the real-time temperature, judging whether the matching degree of the real-time crystal phase image and the target crystal phase image is larger than a first threshold value, and if so, controlling the laser generation module to stop welding;
the polishing mechanism is used for polishing the welding line;
and the annealing mechanism is used for annealing the polished broken wire.
Compared with the prior art, the invention has the beneficial effects that at least:
when the two end parts of the broken wire are positioned, the vision detection module is used for collecting pictures of the two end parts, controlling the two end parts to automatically adjust positions on three shafts, and ensuring concentricity; aligning a target heating light spot with the molten pool part, enabling the matching degree of a real-time crystalline phase image formed on the molten pool part and the target crystalline phase image to be larger than a first threshold value, completing a welding procedure in an automatic control and detection mode, and finally polishing and annealing to complete welding; the welding method is high in automation degree, laser welding is performed by the aid of the laser generating module, heating is fast, efficiency is high, and accurate automatic welding is achieved through judging of crystal phase images.
The invention is described in further detail below with reference to the drawings and the detailed description.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a flow chart of a diamond wire laser welding method in one embodiment.
FIG. 2 is a schematic flow diagram of laser heat welding in one embodiment.
FIG. 3 is a schematic diagram of a positioning mechanism in one embodiment.
Fig. 4 is a schematic diagram of a press block pressing a broken wire against a V-groove of a magnetic platform in one embodiment.
FIG. 5 is a schematic diagram of the structure of an annealing mechanism in one embodiment.
Reference numerals
10-end; 11-a positioning mechanism; 20-a magnetic platform; 20-a magnetic platform; a 21-V groove; 22-briquetting; 31-a clamping device; 32-heating electrode; 33-insulating material.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, when it is described that a specific device is located between a first device and a second device, an intervening device may or may not be present between the specific device and the first device or the second device. When it is described that a particular device is connected to other devices, the particular device may be directly connected to the other devices without intervening devices, or may be directly connected to the other devices without intervening devices.
Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.
Applicants' studies found that:
when the diamond wire breaks, the prior art generally realizes broken wire welding through resistance welding or brazing, and the two modes have the problems of low welding efficiency, poor consistency, low automation degree, poor quality of the welded diamond wire and obviously reduced cutting performance because of the influence of various welding factors. Particularly, for high-carbon steel with carbon content of 0.92% -0.98% or tungsten steel, cracks are easy to generate due to poor plasticity of the high-carbon steel, the welding performance is poor, the melting point of diamond wires of the tungsten steel is above 2850 ℃, and a common welding machine cannot meet the welding requirement.
In view of this, referring to fig. 1, in a first aspect, there is provided a diamond wire laser welding method including:
positioning the two ends of the broken wire so that the two ends are opposite; the two end parts are spaced a certain distance;
respectively shearing the sections of the two end parts to ensure that the two sections have the same sectional area, and cleaning to remove the oxide films and the greasy dirt on the surfaces of the two end parts of the broken wire;
the vision detection module is used for collecting pictures of the two end parts, detecting and calculating concentricity of the two end parts, and controlling the two end parts to automatically adjust positions so that the two end parts are concentric; the two ends of the broken wire are respectively fixed by a positioning mechanism, the positioning mechanism has a triaxial servo centering function, and the cross sections of the ends can be automatically aligned according to the detection and calculation result of concentricity;
aligning the target heating light spot of the laser generating module with a molten pool part formed by two end parts and a limited space around the two end parts, and starting laser heating welding; before laser heating welding, as the two end parts are spaced, when welding is started, the two end parts are irradiated by the target heating light spots, the target heating light spots cover the cross sections of the two end parts and also cover a section of line body after the cross sections, and under the laser heating of the target heating light spots, a molten pool part formed by the two end parts and a limited space around the two end parts starts to be heated and melted;
monitoring the real-time temperature and the real-time crystalline phase of the molten pool part, adjusting the heating power of the laser generating module according to the real-time temperature, controlling the temperature of the molten pool part to be larger than the melting point of the wire rod, judging whether the matching degree of the real-time crystalline phase image and the target crystalline phase image is larger than a first threshold value, and if so, stopping welding; specifically, the target crystal phase image is tested in advance, broken wires of different diamond wire materials and specifications are welded through the combination of a plurality of groups of laser frequency parameters and power parameters, a plurality of groups of diamond wire welding heads are obtained, each group of diamond wire welding heads is tested in strength, and the optimal target crystal phase image and corresponding welding control parameters are determined according to each material and each specification; in the welding process, corresponding welding control parameters are set according to specific diamond wire materials and specifications, matching degree calculation is carried out on a real-time crystal phase image and a target crystal phase image, and only if the matching degree is larger than a first threshold value, the fact that penetration of a molten pool part is achieved can be judged, an ideal crystal phase state is achieved, and welding is stopped;
and then polishing and welding the welded part of the welded diamond wire, and annealing to finish welding.
According to the laser welding method in the embodiment, the traditional manual welding mode is changed through visual detection and automatic control, automatic welding is realized, and welding efficiency is improved.
Referring to fig. 2, as an embodiment, when laser heating welding is performed, a target heating spot is aligned to a molten pool portion, so that metal is melted and gasified to form a heated hole, in the process, liquid metal outside a heated hole wall flows, the surface tension of a wall layer and the vapor pressure continuously generated in the heated hole cavity are maintained in a maintained dynamic balance, and as a light beam continuously enters the heated hole, metal materials outside the heated hole are maintained in a continuous flow, and when the balanced state is reached, the heated hole is always in a flowing stable state;
therefore, the visual detection module is utilized to judge whether the vapor pressure in the heated hole and the surface tension and the gravity of the liquid metal are balanced, whether the state of the heated hole is stable or not and whether the whole size of the heated hole is not expanded or not is judged in a first time interval, if so, the balance of the current heated hole is judged, the target heating light spots are controlled to move along the welding direction of the two end parts, and along with the movement of the light beams, the heated hole is always in a flowing stable state, that is, the heated hole and the molten metal surrounding the heated hole wall move along with the movement direction of the target heating light spots, and the molten metal fills gaps left after the heated hole moves away to form a welding seam.
The laser fusion welding mode in the embodiment has deeper penetration and larger depth-to-width ratio, and the welding characteristic of the high-carbon steel is made up through the thermal stress generated by more concentrated and less heat energy, so that the welding success rate of the high-carbon steel diamond wire is greatly improved, the welding time of the high-carbon steel diamond wire is shortened, the dependence on the welding skill of personnel during the welding of the high-carbon steel diamond wire is reduced, and the degree of automation is effectively improved. In addition, by using the welding mode, the high energy density characteristic of laser can meet the welding of tungsten steel diamond wires with the melting point temperature of more than 2850 ℃.
As one embodiment, when monitoring the real-time crystal phase of the molten pool portion, a scanning electron microscope is used to collect the real-time crystal phase image of the molten pool portion, and cluster analysis is performed on the real-time crystal phase image, so that two results are confirmed:
the first result is a result obtained based on solid-state crystal phase clustering, primary clustering is carried out through the distribution position of the solid-state crystal phase, and structural feature clustering is carried out on the primary clustering result, so that the first result is obtained;
the second result is a result obtained based on liquid crystal phase clustering, primary clustering is carried out through the distribution position of the liquid crystal phase, and structural feature clustering is carried out on the primary clustering result, so that the second result is obtained;
extracting crystal distribution characteristics aiming at the first result to obtain solid crystal phase position characteristic information;
extracting the crystal distribution characteristics of the second result to obtain liquid crystal phase position characteristic information;
the solid crystal phase position characteristic information and the liquid crystal phase position characteristic information represent position distribution information of the solid crystal phase and the liquid crystal phase in a real-time crystal phase image, and a first proportion of a liquid crystal phase distribution area to the real-time crystal phase image is calculated;
according to the same manner, the clustering analysis is carried out on the target crystal phase image obtained according to the preset optimal welding control parameters aiming at the specific diamond wire material and specification, and the second proportion of the liquid crystal phase distribution area to the target crystal phase image in the target crystal phase image is also obtained;
by means of automatic detection and judgment, only when the ratio of the first ratio to the second ratio is greater than a first threshold value, preferably 98%, it is proved that in actual laser welding, it is judged that the weld pool portion of the diamond wire has been melted through, and welding can be stopped.
Since the main component of the diamond wire is silicon, and also part of carbon or tungsten, each component exists in a solid state before laser heating, and exists in a liquid state after laser heating to melt, and the structural characteristics of solid and liquid crystal phases are different, cluster analysis can be performed. Preferably, the above is a cluster analysis for elemental silicon.
Therefore, in this embodiment, after the target heating light spot is aligned to the molten pool portion, the visual detection module is used to collect an image of the molten pool portion, and determine whether the vapor pressure in the heated hole and the surface tension and gravity of the liquid metal reach balance, and if so, then the target heating light spot is moved to form a weld; and then, acquiring a real-time crystal phase image of the molten pool part by using a scanning electron microscope, carrying out cluster analysis on the real-time crystal phase image comprising at least a part of welding lines, calculating a first proportion of a liquid crystal phase distribution area to the real-time crystal phase image, and comparing the first proportion with a second proportion of the liquid crystal phase distribution area to the target crystal phase image in the target crystal phase image, wherein when the ratio of the first proportion to the second proportion is more than 98%, the diamond wire molten pool part is proved to be completely melted, the liquid crystal phase distribution condition is ideal, and after welding cooling is stopped, the good welding line quality can be realized.
Preferably, for diamond wires of different materials and specifications, target crystal phase images are set respectively, and the target crystal phase images are obtained through the following steps: selecting a diamond wire with specific materials and specifications, aligning a target heating light spot of a laser generating module with a part of the diamond wire, wherein the part is a complete part on the diamond wire, melting and gasifying metal on the part to form a heated hole, observing the heated hole by using a visual detection module until the vapor pressure in the heated hole is balanced with the surface tension and gravity of liquid metal, heating along the radial direction of the diamond wire to form a welding seam, and acquiring a crystal phase image of the welding seam by using a scanning electron microscope to acquire the target crystal phase image.
The whole part is selected on the diamond wire for welding, because the laser welding does not need to additionally add welding materials, only the raw materials at the two ends of the broken wire are fused, and the two raw materials are fused together, so that the welding quality is improved, the welding quality is compared with the welding seam formed after the laser heating on the whole diamond wire, the relative physical parameters of the diamond wire still can meet the cutting process requirements of the monocrystalline silicon wafer after the broken wire welding, and the tensile strength of the welding position basically reaches the original diamond wire level.
Because the target crystal phase image is determined in advance according to the specific diamond wire specification, the target crystal phase image comprises the distribution area of the liquid silicon crystal phase and ideal structural characteristics, the ratio of the distribution area ratio of the liquid crystal phase is judged in an image comparison mode, and the welding is stopped after the error is confirmed by adding an artificial naked eye for rechecking.
In the welding process, a near infrared thermal imaging module is used for monitoring a molten pool part to obtain a near infrared image and a thermal imaging image, the near infrared image and the thermal imaging image are transmitted to an imaging processing module for processing, the gray level of the near infrared image and the thermal distribution coefficient of the thermal imaging image are obtained, the gray level and the thermal distribution coefficient are analyzed and processed to judge which position in the molten pool part has uneven heat distribution, the heating power of the laser generating module is reduced by adjusting the on-off duty ratio parameter of the laser generating module aiming at the area with concentrated heat, and the heating power of the laser generating module is increased by adjusting the on-off duty ratio parameter of the laser generating module aiming at the area with insufficient heat, so that the total power of diamond wires is kept at a stable level in the welding process, and the quality consistency of welding seams is ensured.
As one embodiment, the welding cycle is divided into a plurality of stages, the gray level constant of the corresponding near-infrared image and the thermal distribution coefficient constant of the thermal imaging image are determined for each stage according to the diamond wires made of different materials, the corresponding on-off duty ratio parameters are set, and the two ends of the broken wire are subjected to stage welding.
The welding period can be divided into five welding stages of preheating, cleaning, welding, tempering and tempering, according to diamond wires of specific materials and specifications, welding control parameters are set in advance for each welding stage, after a plurality of groups of tests, the group of parameters with the best welding quality are obtained as the optimal welding control parameters, and the optimal laser welding power is determined for each stage to obtain the corresponding switch duty ratio parameters; additionally, by conducting early experiments on five welding stages, the gray level constant of the ideal near infrared image and the thermal distribution coefficient constant of the thermal imaging image of each stage can be determined for comparison with the near infrared image and the thermal imaging image obtained by the near infrared thermal imaging module in the welding process, so that precise heating control in a plurality of welding stages is realized.
Optionally, the laser generating module is a picosecond laser generator, and the two ends of the broken wire are welded in a staged mode by using 600-700 nm wavelength laser.
Wherein, for five welding stages of preheating, cleaning, welding, tempering, quenching and tempering, according to the demand to heat, to the demand of temperature rise, weld with the laser that suits, like: in the preheating stage, the heat requirement is not too high, and laser with lower frequency and lower energy density can be emitted; in the welding stage, the heat requirement is high, rapid heating is required, and laser with higher frequency and higher energy density can be emitted; in the tempering and tempering stages, a relatively stable heat quantity is required to be maintained, the welding quality is finely adjusted, and laser with relatively high frequency and moderate energy density can be emitted.
The laser adjusting function can be automatically switched to different laser frequencies and energy densities according to a welding stage in a program preset mode, so that welding refinement control is improved, appearance and diameter consistency of a welded diamond wire can be improved through staged laser welding control, and the laser adjusting function is particularly important in control of a welding process because no additional welding material is added and can be used immediately after welding is finished, wherein in a tempering stage, the diameter of a welding seam can be adjusted by laser with higher frequency and moderate energy density, so that the outer diameter basically keeps consistent.
In the welding process, the requirement on the fixing stability of two ends of a broken wire is very high, if the two ends are loose in position in the welding process, the welding quality can be affected, and the appearance and the diameter of a diamond wire are directly inconsistent, so in order to solve the problems, the two ends of the broken wire are placed on a magnetic platform provided with a V-shaped groove, and care is needed to be taken that the topmost end of the broken wire still exceeds the top of the V-shaped groove, then a pressing block is used for pressing the broken wire from top to bottom, the pressing block is made of polyurethane, and is vertically pressed to the broken wire, so that the diamond wire is stressed uniformly as much as possible, the phenomenon that the diamond wire moves circumferentially around the center when being stressed obliquely is prevented, the tensile strength of the diamond wire is reduced, meanwhile, a reasonable pressure value is applied to the diamond wire by the polyurethane pressing block, the polyurethane pressing block has a reasonable hardness value, so that diamond particles on the diamond wire cannot penetrate into a polyurethane body when the pressing block is used for positioning the diamond wire, and the pressing block cannot crush diamond particles.
The end part of the broken wire extends out of the magnetic platform for setting an extension distance, preferably, the extension distance of the diamond wire is a fixed value and is 1.5 to 2 times of the diameter of the diamond wire; in the welding process, the diamond wire is required to feed and fill due to the fact that the diamond wire is high in carbon content and has impurities, so that the magnetic platform can horizontally move under the action of the triaxial servo centering mechanism, when laser welding is carried out, a target heating light spot is aligned to a molten pool part formed by two end parts and a limited space around the two end parts, after the molten pool part begins to melt, the two end parts of the broken wire move in opposite directions and are contacted with each other, and better fusion is achieved. Wherein, servo motor in triaxial servo centering mechanism adopts the mode of ration feeding, makes the buddha's warrior attendant line stretch out forward.
In this process, in order to realize effective control to broken wire, prevent broken wire from taking place displacement or rotation, set up:
the mass of the pressing block is m;
the included angle of the V-shaped groove in the magnetic platform is a;
the two inclined surfaces of the V-shaped groove are respectively subjected to vertical pressure F 1 、F 2
Assuming that the diamond particles are cylindrical, the diameter is 0.005mm;
the mass of broken wire contacted with unit area of the magnetic platform is m 1
The pressure applied to the pressing block by the air cylinder is F;
setting the compressive strength of the artificial diamond to 2000Mpa;
setting N diamond particles on the contact surface;
then there are:
[(m 1 + m)*g+F]*1/2*cos a/2=F1=F2
[(m 1 + m)*g+F]*1/2*cosa/(N*π*0.00000625)<2000Mpa
finally, the pressure F applied to the briquette by the cylinder<[78500*N/ (cosa/2)]-(m 1 + m)*g。
The pressure F applied to the pressing block by the air cylinder needs to meet the above formula to ensure that the diamond particles are not crushed, and maintain effective pressing force to avoid the torsion and displacement of the diamond wire.
In addition, the welding strength of the diamond wire is in direct proportion to the welding area and the welding quality of a molten pool, so that the concentricity of two end faces of the diamond wire is extremely important in the welding process, and the relative parallelism of the cross sections of the two end faces and the flatness of the cross sections and the cross section edges determine the welding quality of a welding line. The traditional mode is to cut by utilizing a straight blade, so that the obtained diamond wire is easy to deform, and comprises easy-to-crimp edges of the cross section, inclined planes of the cross section, straight lines of the cross section and the like, and the welding quality of the diamond wire cut under the condition cannot be guaranteed.
Therefore, in this embodiment, when carrying out the section to both ends and shearing, adopt the double-edged ring cutter utensil, apply the shearing force inwards simultaneously along the radial direction of a certain cross-section of broken string, guarantee that the diamond wire is cut off the external diameter atress of department and is even and atress simultaneously in the cutting process, produce stress crack along the cross-section under even radial force, finally break off along vertical cross-section at the tip of diamond wire, form the welded cross-section of perpendicular to broken string axial line, guarantee the parallelism of both ends welded cross-section, the planarization of cross-section edge, thereby the broken cross-section better fuses when guaranteeing the welding, improve welding quality.
As one implementation mode, when the welding line is polished, the welding line formed on the molten pool part is wrapped by a polishing mechanism, silicon carbide is embedded on the contact surface of the polishing mechanism and the welding line, the polishing mechanism is controlled to perform high-hertz micro-amplitude cross-frequency vibration, and surface bubbles and impurities in the welding line are eliminated in the high-frequency vibration process.
Because after laser welding, the broken wire has realized higher diameter uniformity, and the external diameter of welding seam department is slightly greater than the buddha's warrior attendant external diameter, can directly adopt the mode of accurate grinding this moment, carries out the micro amplitude cross frequency vibration with grinding machanism control under 30~50 khz/s's high frequency, directly utilizes embedded buddha's warrior attendant sand to carry out accurate grinding, and under high frequency, can guarantee that the appearance quality of buddha's warrior attendant line is in better state moreover, realizes the low defective rate of later stage in the silicon chip cutting process.
Referring to fig. 3 to 5, in a second aspect, there is provided a welding system applied to the above-described one diamond wire laser welding method in an embodiment of the present disclosure, including:
a positioning mechanism 11 for positioning the broken wire end 10 so that the two ends are opposed to each other; the positioning mechanism 11 comprises a magnetic platform 20 with a V-shaped groove 21, a pressing block 22 and a triaxial servo centering mechanism, wherein the pressing block 22 presses a broken wire on the V-shaped groove 21 of the magnetic platform 20, and the triaxial servo centering mechanism controls the magnetic platform 20 and the pressing block 22 to synchronously move so as to realize centering and diamond wire feeding; in fig. 3, a single positioning mechanism 11 is shown to fix one of the end portions 10 of the broken wire, and two positioning mechanisms 11 are required to be used to position the two end portions respectively so that the two end portions are opposite to each other in order to complete the laser welding of the diamond wire;
the shearing mechanism is used for shearing the sections of the two end parts respectively; the shearing mechanism adopts a double-blade ring cutter, and the end part of the diamond wire is broken along the vertical section to form a welding section vertical to the axial center line of the broken wire;
the cleaning mechanism is used for cleaning the two end parts respectively; through the mode of spraying alcohol, grease on the surface of the broken wire is dissolved, oxide films and greasy dirt at the end part of the broken wire are removed, and air holes and slag inclusion are prevented in the welding process;
the visual detection module is used for collecting pictures of the two end parts, detecting and calculating concentricity of the two end parts, and controlling the positioning mechanism to drive the two end parts to automatically adjust positions so that the two end parts are concentric;
the laser generating module is used for generating target heating light spots aligned with a molten pool part formed by two end parts and a limited space around the two end parts and carrying out laser heating welding; preferably, the laser generating module is a picosecond laser generator, and the two ends of the broken wire are subjected to staged welding by using 600-700 nm wavelength laser;
the detection module is used for monitoring the real-time temperature and the real-time crystal phase of the molten pool part, adjusting the heating power of the laser generation module according to the real-time temperature, judging whether the matching degree of the real-time crystal phase image and the target crystal phase image is larger than a first threshold value, and if so, controlling the laser generation module to stop welding; the detection module comprises a scanning electron microscope, a near infrared thermal imaging module and a processing module, wherein the scanning electron microscope collects real-time crystal phase images of the molten pool part, the processing module performs cluster analysis on the real-time crystal phase images, and whether the matching degree of the real-time crystal phase images and the target crystal phase images is larger than a first threshold value or not is judged; the near-infrared thermal imaging module monitors the molten pool part to obtain a near-infrared image and a thermal imaging image, the near-infrared image and the thermal imaging image are transmitted to the processing module for processing, the gray level of the near-infrared image and the thermal distribution coefficient of the thermal imaging image are obtained through processing, the on-off duty ratio parameter of the laser generating module is determined, and the heating power of the laser generating module is adjusted according to the on-off duty ratio parameter;
the polishing mechanism is used for polishing the welding line; the polishing mechanism wraps the welding seam formed on the molten pool part, silicon carbide is embedded in the contact surface of the polishing mechanism and the welding seam, the polishing mechanism is controlled to perform high-hertz micro amplitude cross-frequency vibration, and surface bubbles and impurities in the welding seam are eliminated
The annealing mechanism is used for annealing the polished broken wire; a large amount of heat is generated in the process of wire breakage welding of the diamond wire; after welding is finished, some heat energy cannot be released in the room-temperature cooling process, so that thermal stress is generated in the molten pool part and the heat affected zone of the molten pool part, and the tensile strength of the material in the molten pool part and the heat affected zone of the molten pool part is reduced; as shown in fig. 5, in the annealing mechanism, the diamond wire is clamped and suspended by the clamping device 31, the heating electrode 32 of the annealing mechanism contacts both ends of the molten pool portion, the heating electrode 32 is a low-resistance alloy conductor, the molten pool portion and the heat affected zone are heated and annealed, and the insulating material 33 is arranged outside the heating electrode 32 to prevent electric shock.
Compared with the prior art, the invention provides the diamond wire laser welding method and the diamond wire laser welding system, when two ends of a broken wire are positioned, images of the two ends are collected through the visual detection module, the two ends are controlled to automatically adjust positions on three axes, and concentricity is ensured; aligning a target heating light spot with the molten pool part, enabling the matching degree of a real-time crystalline phase image formed on the molten pool part and the target crystalline phase image to be larger than a first threshold value, completing a welding procedure in an automatic control and detection mode, and finally polishing and annealing to complete welding; the welding method is high in automation degree, laser welding is performed by the aid of the laser generating module, heating is fast, efficiency is high, and accurate automatic welding is achieved through judging of crystal phase images.
Finally, it should be emphasized that the present invention is not limited to the above-described embodiments, but is merely preferred embodiments of the invention, and any modifications, equivalents, improvements, etc. within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims (6)

1. A method of laser welding a diamond wire, comprising:
positioning the two ends of the broken wire so that the two ends are opposite;
respectively shearing sections of the two end parts, and cleaning;
the vision detection module is used for collecting pictures of the two end parts, detecting and calculating concentricity of the two end parts, and controlling the two end parts to automatically adjust positions so that the two end parts are concentric;
aligning the target heating light spot of the laser generating module with a molten pool part formed by two end parts and a limited space around the two end parts, and starting laser heating welding;
monitoring the real-time temperature and the real-time crystal phase of the molten pool part, adjusting the heating power of the laser generating module according to the real-time temperature, judging whether the matching degree of the real-time crystal phase image and the target crystal phase image is larger than a first threshold value, and stopping welding if the matching degree is larger than the first threshold value;
polishing and annealing the welding line to finish welding;
when laser heating welding is carried out, a target heating light spot is aligned to a molten pool part, metal is melted and gasified to form a heated hole, whether the steam pressure in the heated hole is balanced with the surface tension and the gravity of liquid metal or not is judged by utilizing a visual detection module, and if the steam pressure in the heated hole is balanced with the surface tension and the gravity of the liquid metal, the target heating light spot is controlled to move along the welding directions of two end parts to form a welding seam;
monitoring the molten pool part by utilizing a near infrared thermal imaging module to obtain a near infrared image and a thermal imaging image, determining a switching duty ratio parameter of the laser generating module according to the gray level of the near infrared image and the thermal distribution coefficient of the thermal imaging image, and adjusting the heating power of the laser generating module according to the switching duty ratio parameter;
dividing a welding period into a plurality of stages, determining a gray level constant of a corresponding near infrared image and a thermal distribution coefficient constant of a thermal imaging image for each stage according to diamond wires made of different materials, setting a corresponding switch duty ratio parameter, and performing staged welding on two ends of a broken wire;
placing two ends of the broken wire on a magnetic platform provided with a V-shaped groove, pressing the broken wire from top to bottom by using a pressing block, and enabling the ends of the broken wire to extend out of the magnetic platformThe platform sets the extension distance, and the pressure F applied to the pressing block by the air cylinder<[78500*N/(cosa/2)]-(m 1 +m) g, wherein the mass of the briquette is m, and the mass of the broken wire contacted with the unit area of the magnetic platform is m 1 The included angle of the V-shaped groove in the magnetic platform is a, and the number N of diamond particles is on the contact surface of the broken wire and the magnetic platform.
2. The method for welding diamond wire according to claim 1, wherein the laser generating module is a picosecond laser generator, and the laser with the wavelength of 600 nm-700 nm is used for welding the two ends of the broken wire in a stepwise manner.
3. The method of claim 2, wherein for diamond wires of different materials and specifications, target crystal phase images are set respectively, the target crystal phase images are configured to select one diamond wire, target heating spots of the laser generating module are aligned to a part of the diamond wire, and after the part reaches the balance of vapor pressure and the surface tension and gravity of the liquid metal, heating is completed along the radial direction, the obtained crystal phase images are acquired.
4. A method of laser welding a diamond wire as claimed in claim 3, wherein, in the case of shearing the cross section of both end portions, a double-edged ring cutter is used to simultaneously apply a shearing force inward in a radial direction of a certain cross section of the broken wire so as to form a welded cross section perpendicular to the axial center line of the broken wire at the end portions.
5. The diamond wire laser welding method as set forth in claim 4, wherein when the welding seam is polished, the welding seam formed on the molten pool part is wrapped by a polishing mechanism, and silicon carbide is embedded on the contact surface of the polishing mechanism and the welding seam, so that the polishing mechanism is controlled to perform high-hertz micro amplitude cross-frequency vibration, and surface bubbles and impurities in the welding seam are eliminated.
6. A welding system applied to a diamond wire laser welding method as claimed in any one of claims 1 to 5, comprising:
the positioning mechanism is used for positioning the end parts of the broken wire so that the two end parts are opposite;
the shearing mechanism is used for shearing the sections of the two end parts respectively;
the cleaning mechanism is used for cleaning the two end parts respectively;
the visual detection module is used for collecting pictures of the two end parts, detecting and calculating concentricity of the two end parts, and controlling the positioning mechanism to drive the two end parts to automatically adjust positions so that the two end parts are concentric;
the laser generating module is used for generating target heating light spots aligned with a molten pool part formed by two end parts and a limited space around the two end parts and carrying out laser heating welding;
the detection module is used for monitoring the real-time temperature and the real-time crystal phase of the molten pool part, adjusting the heating power of the laser generation module according to the real-time temperature, judging whether the matching degree of the real-time crystal phase image and the target crystal phase image is larger than a first threshold value, and if so, controlling the laser generation module to stop welding;
the polishing mechanism is used for polishing the welding line;
and the annealing mechanism is used for annealing the polished broken wire.
CN202310774589.XA 2023-06-28 2023-06-28 Diamond wire laser welding method and system Active CN116511712B (en)

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Publication number Priority date Publication date Assignee Title
CN101581840A (en) * 2008-05-16 2009-11-18 北京京东方光电科技有限公司 Liquid crystal display and method for restoring broken wires
DE102010007717A1 (en) * 2010-02-11 2011-08-11 JENOPTIK Automatisierungstechnik GmbH, 07745 Connecting two workpieces using transmission welding, comprises contacting both workpieces over a contact area extending in x-y direction, where the contact area has a joining area, and directing a laser line to the joining area
CN103572291A (en) * 2012-07-25 2014-02-12 苏州协鑫光伏科技有限公司 Corrosive liquid for electroplated diamond wire saw coating and wire saw broken-wire connection method
CN109482874A (en) * 2018-11-29 2019-03-19 湖南大学 Method and system based on Solidification Structures in image monitoring control laser gain material
CN114131141A (en) * 2021-12-28 2022-03-04 中国计量大学 Large-scale structural part displacement welding quality online monitoring method and system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101581840A (en) * 2008-05-16 2009-11-18 北京京东方光电科技有限公司 Liquid crystal display and method for restoring broken wires
DE102010007717A1 (en) * 2010-02-11 2011-08-11 JENOPTIK Automatisierungstechnik GmbH, 07745 Connecting two workpieces using transmission welding, comprises contacting both workpieces over a contact area extending in x-y direction, where the contact area has a joining area, and directing a laser line to the joining area
CN103572291A (en) * 2012-07-25 2014-02-12 苏州协鑫光伏科技有限公司 Corrosive liquid for electroplated diamond wire saw coating and wire saw broken-wire connection method
CN109482874A (en) * 2018-11-29 2019-03-19 湖南大学 Method and system based on Solidification Structures in image monitoring control laser gain material
CN114131141A (en) * 2021-12-28 2022-03-04 中国计量大学 Large-scale structural part displacement welding quality online monitoring method and system

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