CN105228327B - Laser welding small hole plasma electric properties detection means and method - Google Patents
Laser welding small hole plasma electric properties detection means and method Download PDFInfo
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- CN105228327B CN105228327B CN201510664238.9A CN201510664238A CN105228327B CN 105228327 B CN105228327 B CN 105228327B CN 201510664238 A CN201510664238 A CN 201510664238A CN 105228327 B CN105228327 B CN 105228327B
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/0006—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature
- H05H1/0012—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature using electromagnetic or particle radiation, e.g. interferometry
- H05H1/0018—Details
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/20—Bonding
- B23K26/21—Bonding by welding
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/70—Auxiliary operations or equipment
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Abstract
The present invention discloses laser welding small hole plasma electric properties detection means and method, detection means is made up of upper lid and lower cover, and detection agency, water inlet tap, suction nozzle, faucet, outlet nozzle and connecting tube are set wherein, insulating barrier is set in the basal surface of detection means, for being insulated with workpiece, weld seam.Electrical characteristics detection means is used during laser weld, is connected by rheostat, amplifier and capture card with computer, the electrical characteristics signal of laser welding small hole plasma is directly gathered.Technical scheme stability is stronger, and detection range is bigger, and detection time is longer, for the formation and differentiation of aperture in laser welding processes, and the on-line checking of Laser Welding Quality has important practical significance.
Description
Technical field
The invention belongs to laser processing technology, more specifically, and in particular to wrapped in one kind detection laser beam welding
The detection means and method of electrical characteristics containing plasma in aperture and workpiece upper plasma plumage, aperture of the present invention etc. from
The implication of daughter refers under the conditions of deep penetration welding plasma and the plasma gushed out in aperture in aperture.
Background technology
In laser beam welding, high energy laser beam interacts with workpiece and protective gas, produces plasma, also known as
Laser plasma.Laser Welding can be divided into thermal conductivity weldering and deep penetration welding both of which, specifically, be produced in Laser Deep Penetration Welding
Raw plasma includes the plasma in aperture and the plasma plume above workpiece, and can unite referred to as plasma.
Whether the plasma produced in welding process with welding quality difference has important influence to the stabilization of welding process.So
There is important practical significance to the research of laser plasma.
For dialectical angle, laser plasma is the bridge of our exploring laser light welding processes.On the one hand, laser
The important information on welding process is contained in plasma, such as light, electricity and acoustical signal have more research both at home and abroad,
Essential information on welding process can be obtained by the research of information in article on plasma；On the other hand, plasma is to work
The welding quality of part has important influence, is in particular in that scattering and absorption of the plasma plume to laser beam above workpiece are made
With so that the energy density that laser reaches workpiece surface is reduced, and then influences welding quality.Because the present invention is simply related to laser
The detection of plasma electric signal, therefore the prior art detected in this explanation on laser plasma electric signal.General
In terms of the electrical signal detection of steady-state plasma, the most extensive with Langmuir probes, this is a kind of active probe, but not
The detection of the plasma electric characteristic with certain fluctuation produced suitable for laser beam welding.In addition, on passive electrical
The prior art of probe in detecting laser plasma electrical characteristics has, and the passive electric detection device and method of laser plasma are (specially
Profit number 201310513676.6) and detection laser plasma photoelectricity probe and its application method (patent No.
201110360537.5) obtain Patents mandate.It is worth noting that, under Laser Deep Penetration Welding pattern, being full of in aperture
Plasma, in steam pressure, in the state of molten bath static pressure and surface tension are mutually balanced, aperture maintains to open, and welds
Process stabilization.So, Laser Welding Quality is monitored, it is necessary to which the plasma characteristics in aperture are detected.
But, the method office of photoelectricity probe or Langmuir probes or passive electrical probe in detecting plasma is either utilized now
The plasma plume above workpiece is limited, plasma characteristics in not a kind of aperture detected under Laser Deep Penetration Welding pattern
Device and method.
The content of the invention
It is an object of the invention to overcome prior art plasma electric characteristic in aperture under detection Laser Deep Penetration Welding pattern
Limitation, propose a kind of power source model for including the plasma gushed out in small keyhole plasma and aperture, and herein
A kind of device and method that can be detected to aperture plasma electric properties has been invented on basis, has been realized deep to laser
The detection of aperture plasma electric properties under melting welding pattern.
The technical purpose of the present invention is achieved by following technical proposals：
Laser welding small hole plasma electric properties detection means, including electrical signal detection device, the first connecting wire, second
Connecting wire, rheostat, amplifying circuit, data collecting card and computer, wherein：
Electrical signal detection device is connected by the second connecting wire with rheostat；One end of first connecting wire and rheostat
It is connected, the other end is connected with workpiece；Rheostat is connected with amplifying circuit, and amplifying circuit is connected with data collecting card, data acquisition
Card is connected with computer, and laser beam interacts with workpiece and protective gas, the electric current letter formed in plasma, plasma
Connecting wire number through electrical signal detection device and workpiece is drawn, and external load resistance (i.e. rheostat) is flowed through, by amplifying circuit
The voltage signal at load resistance two ends is gathered with data collecting card, can show that the electric current in plasma is believed by voltage and resistance
Number, final voltage signal and current signal are stored into computer；
Electrical signal detection device includes detection agency, lower cover and upper lid；Detection agency is generally cylindric, upper end open,
Lower end sets catch, and laser action mouthful is set in the center of catch, and gas flow outlet, detection are set in the side of laser action mouthful
The center of mechanism is through-hole structure, to provide passage for laser action；The middle position of upper lid and lower cover is provided with through hole, on
Lid and lower cover are connected as a generally columned housing, in enclosure interior formation cavity, are set and cavity phase on lower lid
Water inlet tap, faucet and suction nozzle even；Outlet nozzle is arranged on the catch of detection agency, and its one end is by connecting pipe with entering
Valve is connected, and the other end is connected with gas flow outlet；Detection agency is integrally located in housing, and the upper end of detection agency is fixedly installed
In the through hole of upper lid, the catch of detection agency be fixedly installed on it is in the through hole of lower cover and concordant with the lower surface of lower cover, jointly
The lower surface of electrical signal detection device is constituted, and heat-resistant insulating layer is set on the lower surface of electrical signal detection device.
In the above-mentioned technical solutions, the center of detection agency is through-hole structure, is coordinated with the laser action mouthful in catch center
There is provided passage for laser action, lasing light emitter by probe mechanism by with laser action mouthful, act on workpiece and carry out Laser Welding
Connect；Through-hole structure is made up of the manhole of upper end and the bellmouth of lower end, maximum gauge and the manhole diameter of bellmouth
Unanimously, be less than or equal to 10mm preferably in 6-10mm, to avoid plasma to the lens effect of laser beam, bellmouth
Minimum diameter is 3-5mm, good with the surface of the lower end bellmouth for the through-hole structure for causing laser plasma and detection agency
Contact.
In the above-mentioned technical solutions, the wall thickness of the cylinder-like structure of the upper end of the catch of detection agency is in 2-3mm.
In the above-mentioned technical solutions, the thickness of heat-resistant insulating layer is within 0.5mm, and material selection is heat-resisting (to be directed to Laser Welding
The temperature connect, can bear and not occur to melt deformation etc.) insulating materials, from coating, adhesion；Using heat-resisting
The purpose of insulating barrier is to cut off the current loop that workpiece upper plasma plumage is constituted with welding workpiece so that in plasma
Current signal flow into detection agency, this equivalent to the current loop changed in plasma, realize using electric signal visit
Survey electrical characteristics this purpose of aperture plasma in device detection laser beam welding.
In the above-mentioned technical solutions, fixture is provided with workpiece to be welded, dress is detected with fixed telecommunication number for clamping
Put.
In the above-mentioned technical solutions, enter for convenience the detection agency in the conduction of horizontal electrical signal, electrical signal detection device, under
Lid, upper lid, water inlet tap, faucet, suction nozzle select metal material, preferably copper, entirely will integrally adopt electrical signal detection device
Prepared with metal material, in order to can be connected at any position of electrical signal detection device with the second connecting wire, to
Outer exporting telecommunication number.
In the above-mentioned technical solutions, water inlet tap and faucet are arranged on the two ends of lower cover diameter, so that cooling water is by intaking
Mouth enters after cavity, flows through after most long distance (i.e. the diameter of lower cover), then is preferably whole electric signal from faucet outflow
Detection means provides cooling treatment.
In the above-mentioned technical solutions, suction nozzle is arranged on the middle position of the circular arc of connection water inlet tap and faucet, is used for
The inert gas of laser welding protection, through connecting pipe, into outlet nozzle, then by gas flow outlet outflow, is realized from suction nozzle
Gas shield to laser welding, exists with the separation for realizing gas and cooling water, while cooling water is realized to connecting pipe
Cooling.
In the above-mentioned technical solutions, the gas flow outlet is arranged on catch and through whole catch, to form air guide
Passage, the axis of air guide channel and the angle of the lower surface (i.e. horizontal direction) of whole electrical signal detection device are 30-50 °,
So that inert gas (nitrogen, helium or argon gas) can be protected (protection to laser and style of work region and its surrounding
Weld seam, prevents it from aoxidizing).
In the above-mentioned technical solutions, the connecting pipe selects soft air-guide pipe.
In the above-mentioned technical solutions, outlet nozzle is connected through a screw thread on the catch for being arranged on detection agency.
In the above-mentioned technical solutions, upper lid and lower cover outer surface diameter are between 60-100mm, 3-5mm of wall thickness, cavity
In the range of highly 30-60mm, to ensure cooling effect.
In the above-mentioned technical solutions, the catch of detection agency is threadedly coupled and fixed with lower cover.
In the above-mentioned technical solutions, the upper end of detection agency is fixedly installed on the through hole of upper lid by backing plate and connecting bolt
In, and connecting bolt extends downwardly and is connected with lower cover, so that detection agency, upper lid and lower cover turn into an entirety.
In the above-mentioned technical solutions, detection agency and Shang Gai, upper lid and lower cover, probe mechanism and lower cover junction are set
Sealing ring, the sealing ring prepared from heat-resistant seal material.
The method that aperture plasma electric characteristic is detected using said apparatus, is carried out as steps described below：
Step 1, electrical signal detection device is connected by the second connecting wire with rheostat；One end of first connecting wire with
Rheostat is connected, and the other end is connected with workpiece；Rheostat is connected with amplifying circuit, and amplifying circuit is connected with data collecting card, number
It is connected according to capture card with computer, enters computer through data collecting card after the amplified circuit of voltage at rheostat two ends；Telecommunications
Number detection means is placed in workpiece surface, and lasing light emitter is aligned to the through hole and laser action of detection agency in electrical signal detection device
Mouthful, so that laser beam can be threaded through reaching workpiece surface, the heat-resistant insulating layer of electrical signal detection device with laser action mouthful
Lower surface and workpiece weld seam upper surface height within 2mm；
Step 2, open lasing light emitter and carry out laser welding, while being flowed out using suction nozzle, connecting pipe, outlet nozzle and gas
Mouth input inert protective gas, utilizes water inlet tap and faucet to carry out water cooling；
Step 3, analog voltage signal is converted to digital electric signal by data collecting card, and digital electric signal is through data acquisition line
Into computer and show and store.
In the above-mentioned technical solutions, because electrical signal detection device can plasma be all surrounded, so collecting
Electric signal it is stable, the scope of collection is also maximum.Change external rheostat resistance (i.e. rheostatic resistance value), make its from it is small to
Big change, often changes a resistance value, measures an electric signal, will eventually get bent on aperture plasma C-V characteristic
Line.
Laser plasma (including plasma plume above the plasma and workpiece in aperture) is considered as a power supply,
As shown in fig. 7, inside plasma, due to longitudinally there is barometric gradient P inside apertureeAnd thermograde Te, by formula
(1) understand that potential difference occurs in the inside of aperture.Inside plasma, due to as a power supply of regarding, in aperture
The direction of portion's thermograde is consistent with the direction of electric potential gradient, so electron stream is by (ne,Te) 2 (at B) flow direction (ne,Te)0(O
Place), labeled as je,h.Plasma plume above workpiece be seen as be power source model a part, due to the heart in the plasma
(ne,Te) 0 (at O) place temperature and pressure higher than outside, so the pass between thermograde and barometric gradient and electric potential gradient
System understands that in plasma plume, electron stream is by center (ne,Te) 0 (at O) with radial to boundary (ne,Te) 1 (at A) stream
It is dynamic, labeled as je,pl.The electron stream in aperture is flowed at O at B in summary, then is flowed at O at A, and this is in plasma
The electronics flow direction in portion.Because plasma is in contact with welding workpiece, therefore the electron stream in plasma can flow to welding workpiece,
In order to measure the electron stream in aperture plasma, detected using the electrical signal detection device of the present invention, due in telecommunications
Number detection means lower surface is coated with a floor heat-resistant insulating layer, so when laser plasma sprays out of aperture, passing through laser
Functional port enters after the through hole of detection agency, and the electron stream in plasma will not enter welding workpiece, but flow into explorer
The detection circuit that structure is constituted with external rheostat, (through hole is led to specific detection circuit theory diagrams using the circle of upper end as shown in Figure 8
Hole and the bellmouth of lower end, are contacted by the surface of lower end bellmouth with laser plasma), it can so realize that Laser Welding is taken over
The detection of aperture plasma electric properties in journey.In view of the influence of plasma mesotheca effect layer, the current potential on detection agency
For formula (2) Suo Shi.
In formula (1), (2)For the electric potential gradient in plasma, neFor electron density, TeFor electron temperature, e
For electron charge, miFor mass of ion, φprobeFor the current potential (current potential i.e. on electrical signal detection device) on detection agency；For electron temperature gradient,For electron density gradient, k is Planck's constant.
Compared with prior art, detection method of the invention and detection means and existing detection laser plasma body method be most
Big is not both to be, detection means proposed by the invention and detection method can be detected in laser welding processes in aperture etc. from
Daughter electrical characteristics, this is that existing technology can not accomplish.In addition, this detection method for laser plasma, surely
Qualitative stronger, detection range is bigger, and detection time is longer, for the formation and differentiation of aperture in laser welding processes, laser welding
The on-line checking of quality has important practical significance.
Brief description of the drawings
Fig. 1 is the general layout signal of aperture plasma electric properties detection means in laser beam welding of the invention
Figure, wherein 13- welding workpieces, 14- weld seams, 15- electric signal detection devices, the connecting wires of 16- first, for connecting welding work
Part, 17- rheostats, 18- amplifying circuits, 19- data collecting cards, 20- computers, the connecting wires of 21- second, for connecting telecommunications
Number detection device, 22- laser beams, 23- fixtures.
Fig. 2 is the three-dimensional appearance schematic diagram of the electric signal detection device of the present invention, wherein 1- detection agencies, 3-lower cover, 4-
Covered on water inlet tap, 5-, 6- backing plates, 7- connecting bolts, 9- suction nozzles, 10- faucets.
Fig. 3 is the top view of the electric signal detection device of the present invention, wherein 1- detection agencies, 4- water inlet taps, is covered on 5-, 6-
Backing plate, 7- connecting bolts, 9- suction nozzles, 10- faucets.
Fig. 4 is the sectional view in B-B directions in corresponding diagram 3, wherein 1- detection agencies, 2- outlet nozzles, 3- lower covers, 4- water inlets
Covered on mouth, 5-, 6- backing plates, 7- connecting bolts, 8- sealing rings, 10- faucets, 12- heat-resistant insulating layers.
Fig. 5 is that the electric signal detection device of the present invention disassembles view, wherein 1- detection agencies, and 1-1 is laser action mouthful,
1-2 is gas flow outlet, 2- outlet nozzles, 3- lower covers, 4- water inlet taps, is covered on 5-, 6- backing plates, 7- connecting bolts, 8- sealing rings, 9-
Suction nozzle, 10- faucets, 11- flexible pipes.
Fig. 6 is the electric signal detection device of the present invention and the position relationship schematic diagram of welding workpiece, wherein 13- Welders
Part, 14- weld seams, 15- electric signal detection devices, 22- laser beams, 23- fixtures, h is detection agency insulating barrier lower surface and welding
The distance between workpiece.
Fig. 7 is aperture plasma electrical source modular concept figure, wherein 13- welding workpieces, and 22- laser beams, 24- welding is molten
Pond, 25- apertures, 26- plasma plumes, B points are located among aperture, and O points are located in plasma plume, and A points are located at welding pool
In, the radius that opens of plasma plume is labeled as R.
Fig. 8 is to utilize aperture plasma electric properties in electric signal detection device proposed by the present invention detection laser welding processes
Circuit theory schematic diagram, wherein 12- heat-resistant insulating layers, 13- welding workpieces, 15- electric signal detection devices, 17- rheostats,
22- laser beams, 24- welding pools, 25- apertures, 26- plasma plumes.
Under Fig. 9 is Laser Deep Penetration Welding pattern, the electric signal of the aperture plasma collected, electric signal is external rheostat
Resistance value is gained under 2000 Ω.
Figure 10 is the face of weld shape appearance figure obtained under Laser Deep Penetration Welding pattern.
Figure 11 is the seam cross-section shape appearance figure obtained under Laser Deep Penetration Welding pattern.
Under Figure 12 is laser thermal conductivity weldering pattern, the electric signal of the aperture plasma collected, electric signal is external variable resistance
Device resistance value is gained under 2000 Ω.
Figure 13 is the face of weld shape appearance figure obtained under laser thermal conductivity weldering pattern.
Figure 14 is the seam cross-section shape appearance figure obtained under laser thermal conductivity weldering pattern.
Figure 15 is the electric signal divided stages schematic diagram of the aperture plasma collected under Laser Deep Penetration Welding pattern.
Figure 16 is the graph of relation between voltage magnitude and external rheostat resistance value in laser beam welding, wherein bent
Line 1 is the welding starting stage --- keyhole formation starting stage (i.e. I-stage) voltage magnitude and the relation of rheostat resistance value are bent
Line chart, curve 2 is the welding stabilization sub stage --- aperture stabilization sub stage (i.e. III stages) voltage magnitude and the pass of rheostat resistance value
It is curve map.
Figure 17 is the laser welding starting stage, i.e. the Voltammetric Relation curve of keyhole formation starting stage aperture plasma
Figure.
Figure 18 is the laser welding stabilization sub stage, i.e. the Voltammetric Relation curve map of aperture stabilization sub stage aperture plasma.
Embodiment
Technical scheme is further illustrated with reference to specific embodiment.
As shown in accompanying drawing 1-5, laser welding small hole plasma electric properties detection means of the invention, including electric signal inspection
Device, the first connecting wire, the second connecting wire, rheostat, amplifying circuit, data collecting card and computer are surveyed, wherein：
Electrical signal detection device is connected by the second connecting wire with rheostat；One end of first connecting wire and rheostat
It is connected, the other end is connected with workpiece；Rheostat is connected with amplifying circuit, and amplifying circuit is connected with data collecting card, data acquisition
Card is connected with computer；
Whole electrical signal detection device is integrally prepared using metallic copper, electrical signal detection device include detection agency,
Lower cover and upper lid；Detection agency is generally cylindric, upper end open, and lower end sets catch, sets laser to make in the center of catch
With mouth, gas flow outlet is set in the side of laser action mouthful, and the center of detection agency is through-hole structure, thinks that laser action is carried
For passage；The middle position of upper lid and lower cover is provided with through hole, and upper lid and lower cover are connected as a generally columned shell
Body, in enclosure interior formation cavity, sets water inlet tap, faucet and the suction nozzle being connected with cavity on lower lid；Outlet nozzle is set
Put on the catch of detection agency, its one end is connected by connecting pipe with suction nozzle, the other end is connected with gas flow outlet, gas
Body flow export is arranged on catch and through whole catch, to form air guide channel, the axis of air guide channel and whole telecommunications
The angle of the lower surface of number detection means is 30 °；Detection agency is integrally located in housing, and the upper end of detection agency is fixedly installed on
In the through hole of upper lid, the catch of detection agency be fixedly installed on it is in the through hole of lower cover and concordant with the lower surface of lower cover, common group
Into the lower surface of electrical signal detection device, and the setting heat-resistant insulating layer 0.5mm on the lower surface of electrical signal detection device.
The center of detection agency is through-hole structure, and the laser action mouthful with catch center is logical with laser action offer is combined into
Road, lasing light emitter by probe mechanism by with laser action mouthful, act on workpiece and carry out laser welding；Through-hole structure is by upper end
Manhole and lower end bellmouth composition, the maximum gauge of bellmouth is consistent with manhole diameter, is 10mm, taper
The minimum diameter in hole is 5mm.The wall thickness of the cylinder-like structure of the upper end of the catch of detection agency is in 2mm.
Water inlet tap and faucet are arranged on the two ends of lower cover diameter, and suction nozzle is arranged on the circle of connection water inlet tap and faucet
The middle position of arc, upper lid is 100mm with lower cover outer surface diameter, and wall thickness 3mm, housing depth is 60mm；Outlet nozzle passes through spiral shell
Line connection is arranged on the catch of detection agency；The catch of detection agency is threadedly coupled and fixed with lower cover；Detection agency it is upper
End is fixedly installed on by backing plate and connecting bolt in the through hole of upper lid, and connecting bolt is extended downwardly and is connected with lower cover, so that
Detection agency, upper lid and lower cover turn into an entirety；The company of detection agency and Shang Gai, upper lid and lower cover, probe mechanism and lower cover
Meet place and sealing ring, the sealing ring prepared from heat-resistant seal material are set.
As shown in fig. 6, the heat-resistant insulating layer of electrical signal detection device lower surface and workpiece weld seam upper surface height
In 2mm, fixture is provided with workpiece to be welded, for clamping and fixed telecommunication detection means.
Electrical signal detection device is connected by the second connecting wire with rheostat；One end of first connecting wire and rheostat
It is connected, the other end is connected with workpiece；Rheostat is connected with amplifying circuit, and amplifying circuit is connected with data collecting card, data acquisition
Card is connected with computer, enters computer through data collecting card after the amplified circuit of voltage at rheostat two ends；Electrical signal detection
Device is placed in workpiece surface, and lasing light emitter is aligned to the through hole and laser action mouthful of detection agency in electrical signal detection device, opened
Lasing light emitter carries out laser welding, while utilizing suction nozzle, connecting pipe, outlet nozzle and gas flow outlet input inertia protection gas
Body, water cooling is carried out using water inlet tap and faucet so that whole electrical signal detection device maintains a relatively low temperature model
Within enclosing, it is to avoid laser welding produces influence of the heat to equipment.
The equipment of the embodiment of the present invention uses Nd:YAG laser, 1.06 μm of optical maser wavelength, condenser lens focal length 300mm,
Welding process is using laser surface from melting method, and thickness of slab 3mm, protection gas used in experiment is Ar gas, throughput 25L/min, defocus
Amount -1mm, material selection Laser Welding plasma erupts stronger A304 stainless steels, and selected welding parameter is as shown in table 1.
Table 1
| Laser power | Speed of welding | Defocusing amount | Protection air-flow amount |
| 1200w | 4mm/s | -1 | 25L/min |
After laser beam welding electric signal is collected, conditioned circuit amplification and filtering utilize capture card to carry out A/D conversions
And store, and it is transferred to computer.
Fig. 9-11 is electric signal, face of weld pattern and the seam cross-section shape appearance figure (telecommunications under Laser Deep Penetration Welding pattern
Number be that external load resistance is gained under 2000 Ω), under stable deep penetration welding pattern, electric signal occur initial stage one compared with
Big peak value, after transition stage, electric signal remains stable.Face of weld is bright and clean smooth, and workpiece is penetrated.This be due to
In welding process, after keyhole formation, the state opened is maintained, laser energy can sufficiently enter aperture.
Figure 12-14 is electric signal, face of weld pattern and the seam cross-section shape appearance figure (telecommunications under laser thermal conductivity weldering pattern
Number it is that external load resistance is gained under 2000 Ω), the electric signal under thermal conductivity weldering pattern is not initial in time domain scale
Peak value, and have the variation tendency completely contradicted with the electric signal under deep penetration welding pattern.With the progress of welding process, electric signal
The absolute value of amplitude first increases remains stable afterwards, and the absolute value of electric signal amplitude is respectively less than deep penetration welding pattern in time domain scale
The initial spike of lower electric signal.Compared with deep penetration welding pattern, the welding seam deep width ratio under thermal conductivity weldering pattern seriously reduces.
The electrical characteristics of the aperture plasma in laser welding are detected, so the present invention chooses the electricity under deep penetration welding pattern
Signal, finds after analyzing it, by electric signal detection to Laser Deep Penetration Welding pattern under electric signal can be with
Illustrate the process of Laser Deep Penetration Welding well.As shown in figure 15, it is electric signal divided stages schematic diagram under deep penetration welding pattern.According to
Conventional result of study can be divided into three phases to it, and (electric signal applied in Figure 15 is that rheostat resistance value is 2000
The electric signal obtained during Ω, intercepts 0.6s time range).
I：The starting stage (under deep penetration welding pattern, the starting stage of keyhole formation) is welded, time range is in 1-10ms；
II：In the welding transition stage (under deep penetration welding pattern, stage of the aperture from formed to stablizing), time range is in 0.5s；III：Weldering
Connect the stabilization sub stage (under deep penetration welding pattern, the aperture stable stage).
For divided three phases, weight analysis welding starting stage (I-stage) and stabilization sub stage (III ranks
Section).Tested using aperture plasma electric properties detection method proposed above, external rheostat resistance value is in 0-25k
Change between Ω, depict the voltage magnitude and resistance of keyhole formation starting stage (I-stage) and aperture stabilization sub stage (III stages)
Relation curve between value.As shown in figure 16, it can be found that during I and III, the absolute value of voltage magnitude is with rheostatic
The increase of resistance value and increase, change little after in 20k Ω, basically reach saturation.Weld the electric signal amplitude of starting stage
Absolute value be higher than the stabilization sub stage electric signal amplitude absolute value.The relation determined between magnitude of voltage and resistance value is bent
Line, and then the VA characteristic curve on aperture starting stage (I-stage) and stabilization sub stage (III stages) can be depicted.
Figure 17 is the in vitro VA characteristic curve figure such as keyhole formation starting stage (I-stage) to weld initial rank, can be with
Find out, at welding starting stage (I-stage), volt-ampere curve is straight line, i.e., under the conditions of laser power is 1200w (cw),
It is certain value (about 2370 ohm) as the internal resistance of the aperture plasma of power supply.And in welding stabilization sub stage (III stages) etc.
The volt-ampere curve (such as Figure 18) of ion is a curve, and the now internal resistance of aperture plasma is not a definite value.
In summary：The present invention proposes a kind of new electricity for including plasma and workpiece upper plasma plumage in aperture
Source model, and a kind of detection means and detection method for detecting aperture plasma electric properties is proposed on this basis, can be with
The detection to the electrical characteristics of aperture plasma in laser welding processes is realized, i.e., laser welding small hole plasma electricity of the invention is special
Property detection means, electrical signal detection device and method in detection laser beam welding in aperture plasma electric properties should
With the electric signal under collection Laser Deep Penetration Welding pattern in the case of fixed outer meeting resistance resistance, in fixed outer meeting resistance resistance
In the case of gather laser thermal conductivity weldering pattern under electric signal, change outer meeting resistance resistance in the case of be directed to Laser Deep Penetration Welding
The relation curve and VA characteristic curve of magnitude of voltage and resistance value under pattern.
Exemplary description is done to the present invention above, it should explanation, in the situation for the core for not departing from the present invention
Under, any simple deformation, modification or other skilled in the art can not spend the equivalent substitution of creative work equal
Fall into protection scope of the present invention.
Claims (8)
1. laser welding small hole plasma electric properties detection means, it is characterised in that including electrical signal detection device, the first connection
Wire, the second connecting wire, rheostat, amplifying circuit, data collecting card and computer, wherein：
Electrical signal detection device is connected by the second connecting wire with rheostat；One end of first connecting wire and rheostat phase
Even, the other end is connected with workpiece；Rheostat is connected with amplifying circuit, and amplifying circuit is connected with data collecting card, data collecting card
It is connected with computer；
Electrical signal detection device includes detection agency, lower cover and upper lid；Detection agency is generally cylindric, upper end open, lower end
Catch is set, laser action mouthful is set in the center of catch, gas flow outlet, detection agency are set in the side of laser action mouthful
Center be through-hole structure, to provide passage for laser action；The middle position of upper lid and lower cover is provided with through hole, upper lid and
Lower cover is connected as a generally columned housing, in enclosure interior formation cavity, sets what is be connected with cavity on lower lid
Water inlet tap, faucet and suction nozzle；Outlet nozzle is arranged on the catch of detection agency, and its one end passes through connecting pipe and suction nozzle
It is connected, the other end is connected with gas flow outlet, gas flow outlet is arranged on catch and through whole catch, led to forming air guide
Road, the axis of air guide channel and the angle of the lower surface of whole electrical signal detection device are 30-50 °；Detection agency entirety position
In in housing, the upper end of detection agency is fixedly installed in the through hole of lid, and the catch of detection agency is fixedly installed on lower cover
It is in through hole and concordant with the lower surface of lower cover, the lower surface of electrical signal detection device is collectively constituted, and in electrical signal detection device
Lower surface on heat-resistant insulating layer is set；The center of detection agency is through-hole structure, is coordinated with the laser action mouthful in catch center
Passage is provided for laser action.
2. laser welding small hole plasma electric properties detection means according to claim 1, it is characterised in that through-hole structure
It is made up of the manhole of upper end and the bellmouth of lower end, the maximum gauge of bellmouth is consistent with manhole diameter, is small
In equal to 10mm, the minimum diameter of bellmouth is 3-5mm.
3. the laser welding small hole plasma electric properties detection means according to claims 1 or 2, it is characterised in that resistance to
The thickness of thermal insulation layer is within 0.5mm.
4. the laser welding small hole plasma electric properties detection means according to claims 1 or 2, it is characterised in that
Fixture is provided with workpiece to be welded, for clamping and fixed telecommunication detection means.
5. the laser welding small hole plasma electric properties detection means according to claims 1 or 2, it is characterised in that enter
Water nozzle and faucet are arranged on the two ends of lower cover diameter, and suction nozzle is arranged on the central position of the circular arc of connection water inlet tap and faucet
Put.
6. the laser welding small hole plasma electric properties detection means according to claims 1 or 2, it is characterised in that go out
Valve is connected through a screw thread on the catch for being arranged on detection agency；The catch of detection agency is threadedly coupled and fixed with lower cover.
7. the laser welding small hole plasma electric properties detection means according to claims 1 or 2, it is characterised in that visit
The upper end for surveying mechanism is fixedly installed on by backing plate and connecting bolt in the through hole of upper lid, and connecting bolt is extended downwardly and lower cover
Connection so that detection agency, upper lid and lower cover turn into entirety, detection agency and Shang Gai, upper lid and lower cover, probe mechanism and
The junction of lower cover sets sealing ring.
8. the laser welding small hole plasma electric properties detection means according to claims 1 or 2, it is characterised in that visit
The wall thickness of cylinder-like structure of the upper end of the catch of mechanism is surveyed in 2-3mm, upper lid is with lower cover outer surface diameter in 60-100mm
Between, 3-5mm of wall thickness, 30-60mm of housing depth.
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| CN201510664238.9A CN105228327B (en) | 2015-10-14 | 2015-10-14 | Laser welding small hole plasma electric properties detection means and method |
| CN201710227628.9A CN107105564B (en) | 2015-10-14 | 2015-10-14 | Laser welding small hole plasma electric properties detection method |
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| CN107438327A (en) * | 2017-08-22 | 2017-12-05 | 华中科技大学 | A kind of plasma electrical signal online measurement apparatus and method |
| CN109175820B (en) * | 2018-11-12 | 2019-07-12 | 湖南大学 | A kind of comprehensive device directly observed of metal material penetration fustion welding keyhole profile |
| CN110702645A (en) * | 2019-09-23 | 2020-01-17 | 天津大学 | Method for detecting expansion speed and space temperature distribution of laser fusion welding plasma |
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| Publication number | Publication date |
|---|---|
| CN107105564A (en) | 2017-08-29 |
| CN105228327A (en) | 2016-01-06 |
| CN107105564B (en) | 2019-03-26 |
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