CN1267579A - Sound signal sensing method and system for the perforative state of plasma arc welding bath - Google Patents
Sound signal sensing method and system for the perforative state of plasma arc welding bath Download PDFInfo
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- CN1267579A CN1267579A CN 00105933 CN00105933A CN1267579A CN 1267579 A CN1267579 A CN 1267579A CN 00105933 CN00105933 CN 00105933 CN 00105933 A CN00105933 A CN 00105933A CN 1267579 A CN1267579 A CN 1267579A
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Abstract
The present invention relates to the quality control in plasma arc welding. By means of microphones installed near plasma welding gun and data collecting system, sound signal is collected and stored in computer during plasma arc welding; the collected sound signal is processed to obtain a sensed signal for the computer to judge whether the bath is perforated or not; and the sensed signal is finally compared with a threshold value to judge the perforative state of the bath. The present invention has simple system structure and low cost and is practical.
Description
The invention belongs to PLASMA ARC WELDING Quality Control Technology field.
In the high energy beam current process technology that is described as " 21st century process technology ", plasma arc has the cheap characteristics of the simple use cost of equipment, in commercial production, especially in the Aero-Space manufacturing industry, be widely used in welding the non-ferrous metal such as aluminium, copper of easy oxidation and alloy thereof, stainless steel, high temperature alloy, titanium or titanium alloy, and the active metal of infusibility etc.Because the energy density high penetrating power of plasma arc is strong, electric arc arc core diameter is thin, the arc core of plasma arc and arc flame are simultaneously to workpiece 10 heating during welding, arc energy is goed deep into the molten bath and is excavated liquid metal, thereby cause the aperture 11 of a penetrability at the molten bath head, the arc-through aperture forms wake flame 12 at back of weld, after this along with welding torch 14 moves forward, liquid metal in the molten bath relies on capillary support, solid-state wall along the molten bath flows to the molten bath afterbody, crystallisation by cooling forms weld seam 13, as shown in Figure 1.This shows that the stable of the medium and small poroid attitude of plasma arc welding termination process is the key that guarantees complete penetration of weld seam and Forming Quality.Yet the fluctuation of various normality conditions is unavoidable in the actual production, will certainly influence the stability of " keyhole effect ", and for example: aperture is closed in welding process, causes occurring not defective such as penetration and has a strong impact on the welding product quality.Propose to detect in real time automatically the Research on Sensing of " aperture " state, so that lay the foundation for plasma arc weld seam penetration Quality Control for this reason.
From the present situation that at present domestic and international plasma welding is delivered a child and produced and study, the method for detection molten bath aperture state has following several, as shown in Figure 2.The method that detects in back of work has: back side light signal is surveyed method, back side electric arc wake flame conductive method and back side voice signal detection method.Back side optical signal detecting method is shown in Fig. 2 a, and this method is to utilize the various photoelectric devices 201 that are placed in workpiece 200 back sides to detect back of weld radiation light intensity, thereby knows whether the molten bath bores a hole.Back side plasma flame flow conductive method is shown in Fig. 2 b, this method is that a copper coin 203 is placed on workpiece 204 back sides, and keep certain distance with workpiece, when the molten bath produces perforation, the plasma flame flow 205 of passing aperture reaches on the copper coin 203, because isoionic conductive characteristic can get access to voltage behind the additional power source on resistance R, with its rectification output U
o, U
oSize and the size of aperture certain relation is arranged.Back side voice signal detection method shown in Fig. 2 c, is mainly used in welded tube, and microphone 206 is placed on pipeline one side, detects the voice signal of pipe interior, judges according to the variation of voice signal whether aperture exists.More than the common feature of various detection methods be that sensor is placed in back of work, therefore to the welding of some labyrinths, its application is restricted.From the positive method that detects of workpiece spectrographic method and CCD camera method are arranged.Spectrographic method is shown in Fig. 2 d, this method is by optical fiber 209 optical signal transmission that area array CCD obtains to be arrived spectroanalysis instrument, judge with respect to line strength of argon whether the molten bath aperture exists by hydrogen in the spectroanalysis instrument detection workpiece 210 frontal arc light signals 211.The CCD camera method is directly observed the aperture image by CCD shown in Fig. 2 e, but because the restriction in space, the molten bath aperture image that uses CCD to photograph in the workpiece front is out of shape, and this can make troubles to subsequent treatment.These two kinds of methods are because causes such as complex structure, equipment price costliness or disposal route complexity also are in conceptual phase, and using on producing has certain difficulty.
The present invention is intended to overcome the deficiency of prior art, by using the voice signal in the welding process, a kind of sound sensor method and device of perforative state of plasma arc welding bath are proposed, for the automatic Penetration control of PLASMA ARC WELDING that realizes cut deal provides necessary feedback information.Owing to utilize voice signal as sensor source signal, therefore have advantages such as system architecture is simple, with low cost, in production practices, promote easily.
The voice signal detection method of a kind of PLASMA ARC WELDING molten bath perforation state that the present invention proposes is characterized in that, may further comprise the steps:
1) utilizes the sound microphone, obtain the voice signal s (t) in the plasma arc welding termination process, voice signal s (t) is gathered and be stored into computing machine in real time by signal acquiring system;
2) processing that the voice signal sequence s (n) that gathers is made the A algorithm is handled, and obtaining can be for the quantitative molten bath of the machine recognition transducing signal A that whether bores a hole
s
3) with A
sThe threshold value of whether boring a hole with molten bath given in advance compares, to judge the state of molten bath perforation at that time.
Described voice signal is processed the A algorithm of processing, may further comprise the steps:
1) design analysis rectangular window function g (n-m), the voice signal sequence s (n) that computing machine is got access to makes discrete windowing Fourier transform (DWFT).
2) to the windowing Fourier transform DWFT as a result that disperses
s(m, k), do following processing:
(f in the formula
1, f
2---the frequency of voice signal, f
1=0Hz,
f
2=100Hz), draw A (m), it is done promptly to get sound sensor signal A after the smoothing processing
s
In the above-mentioned voice signal detection method, the said molten bath threshold decision criterion of whether boring a hole is: set the threshold value of whether boring a hole in the molten bath and the critical value of molten bath transition state, work as A
sWhen signal amplitude is higher than the molten bath transition state critical value of setting, think that the molten bath is in the do not bore a hole perforation or the transition period of or not of boring a hole; Work as A
sSignal amplitude descends and when being lower than the threshold value of whether boring a hole in the molten bath, can confirm that the molten bath bores a hole, has realized normal perforate PLASMA ARC WELDING; And work as A
sWhen signal amplitude is lower than the critical value of molten bath transition state and is higher than the threshold value of whether boring a hole in the molten bath, judge that then the molten bath is puncherless state.
Principle of the present invention is as follows: sound wave is a kind of mechanical wave, by the pulsation of the vibration of solid or fluid and produce.The source of welding current is supplied with arc energy in the welding process, this energy by arcing in the molten bath, the form that wherein portion of energy can be vibrated with the molten bath, the plasma air-flow is pulsed shows, when the molten bath state changes in the welding process, the condition of molten bath vibration changes thereupon, cause the vibration in molten bath, the pulsation changing features of plasma air-flow, this variation also can reflect in voice signal to some extent, thereby might seek the information of reflection molten bath state by analyzing and processing to voice signal.
The realization principle of the inventive method as shown in Figure 3.At first utilize the high precision microphone, obtain the voice signal s (t) in the plasma arc welding termination process, voice signal s (t) is gathered and be stored into computing machine in real time by signal acquiring system.Voice signal itself can not be as transducing signal and directly in order to judge whether the molten bath aperture exists, but this signal is carrying the characteristic information that can reflect molten bath perforation and puncherless state, this characteristic information is handled by the processing of the transducing signal extraction algorithm (A algorithm) of exploitation, and just having obtained can be for the quantitative molten bath perforation state transducing signal A of machine recognition
sFurther combined with the molten bath threshold decision criterion of whether boring a hole of design, A
sWhether signal just can exist in order to detect the molten bath aperture.Wherein transducing signal extraction algorithm and threshold decision method are to realize by the program software of establishment in advance that is stored in the computing machine.
Sound signal collecting system in the plasma arc welding termination process of the present invention is by sound transducer, data collecting card, computing machine and relevant interface, and be stored in the computing machine corresponding sound signal collecting process software and form, as shown in Figure 4, among the figure, voice signal is input to the input terminal of data collecting card by sound transducer, and data collecting card directly inserts the associated socket of computing machine.Wherein, directly by placing near the microphone 43 the welding torch to obtain, data collecting card is finished signals collecting, analog to digital conversion in conjunction with the data collection application of the present invention's exploitation to voice signal, and the interface that utilizes capture card and computing machine with signal storage in computing machine.
Algorithm and the corresponding method for extracting signal that extracts molten bath perforation state transducing signal from the characteristic information that voice signal carries of the present invention is as follows:
1) analysis rectangular window function g (n-m) reasonable in design:
I in the formula---analyze the rectangular window function moving step length, can be according to the actual conditions round numbers
Counting of N---Fourier transform
N, m---natural number, n=0,1,2 ...., m=0,1 ...
2) the voice signal sequence s (n) that computing machine is got access to makes discrete windowing Fourier transform (DWFT):
K-k gets 0,1 in the formula .., N-1
3) to the windowing Fourier transform DWFT as a result that disperses
s(m, k), do following processing:
F in the formula
1, f
2---the frequency of voice signal, f
1=0Hz, f
2=100Hz draws A (m), it is done level and smooth
Promptly get sound sensor signal A after the processing
s
The state threshold judgment criterion is bored a hole as shown in Figure 5 in the molten bath of the present invention's design, and horizontal ordinate is the time among the figure, and ordinate is A
sSignal amplitude, A
sSignal rule signal over time is as curve C.As seen from the figure, A
sSignal can reflect the state in molten bath: when the molten bath is in perforation during the stage, signal amplitude is minimum, shown in BD section on the time shaft; When the molten bath was puncherless state, signal amplitude was higher, as before the A point on the time shaft or E point later shown in; And the molten bath is when boring a hole transition period, and signal amplitude is the highest, shown in AB section on the time shaft or DE section.Threshold method judges that the process whether bore a hole in the molten bath is: work as A
sSignal amplitude is higher than the molten bath transition state critical value T of setting
1The time, think that the molten bath is in the do not bore a hole perforation or the transition period transition period of or not of boring a hole; Work as A
sSignal amplitude is lower than the threshold value T whether bore a hole in the molten bath
2The time, confirm as the molten bath and bore a hole, realized normal perforate PLASMA ARC WELDING; And work as A
sThe critical value T of the low sub-molten bath of signal amplitude transition state
1And be higher than the threshold value T whether bore a hole in the molten bath
2The time, judge that then the molten bath is puncherless state.
Detection method of the present invention is the sensing molten bath state of whether boring a hole effectively, can be the automatic Penetration control of PLASMA ARC WELDING that realizes cut deal necessary feedback information is provided.Owing to utilize sound in the welding process as sensor source signal, therefore have advantages such as system architecture is simple, with low cost with respect to other detection method, be easy in production practices, promote
Brief Description Of Drawings:
Fig. 1 is a perforate plasma arc welding termination process synoptic diagram.
Fig. 2 is several molten bath perforation condition detection method synoptic diagram in the prior art; Wherein,
Fig. 2 a surveys method for back side light signal,
Fig. 2 b is a back side plasma flame flow conductive method,
Fig. 2 c is a back side voice signal detection method,
Fig. 2 d is a spectrographic method,
Fig. 2 e is the CCD camera method.
Fig. 3 is that method of the present invention realizes theory diagram.
Fig. 4 is that sound signal collecting of the present invention system forms synoptic diagram.
The molten bath that Fig. 5 designs for the present invention threshold decision criterion synoptic diagram of whether boring a hole.
Fig. 6 is the software flow block diagram that the A algorithm of present embodiment is realized.
Fig. 7 is that the sound signal collecting system of present embodiment forms synoptic diagram.
Fig. 8 a is the back side fluting Workpiece structure synoptic diagram of present embodiment,
Fig. 8 b is the molten bath perforation status detection sign picture as a result of present embodiment
Fig. 8 c is the transducing signal A of present embodiment acquisition
sCurve map,
The sound signal sensing method and the system embodiment thereof of a kind of perforative state of plasma arc welding bath of the present invention's design are described with reference to the accompanying drawings as follows:
Consider the variation of conditions such as radiating condition in the actual production, thickness of workpiece and welding conditions, present embodiment adopts back side fluting workpiece, set welding variables assurance welding arc is not bored a hole in molten bath, workpiece thick 6mm place, and the perforation of molten bath, 4mm place uses inverter type welder to weld on stainless steel work-piece.
The sound signal collecting system of present embodiment is made up of sound transducer, data collecting card, computing machine and relevant interface, as shown in Figure 7.Voice signal is input to the input terminal of data collecting card then by placing near the microphone 71 the welding torch to obtain, and data collecting card directly inserts the associated socket of computing machine.Microphone adopts high precision sound pressure sensor JL-1, the response band width reaches 20kHz, the voltage of microphone output has the comparatively linear relationship of strictness with the acoustic pressure of voice signal, and the voltage that has guaranteed to be transported to data collecting card like this can reflect the acoustic pressure in the welding process comparatively exactly.The data collecting card model is " PCI-9118HG ", 12 of precision, the highest picking rate 330kHz, each continuous acquisition data capacity can reach 64M, and this card is finished signals collecting, analog to digital conversion in conjunction with the data collection application of the present invention's exploitation, and the interface that utilizes capture card and computing machine with signal storage in computing machine, computing machine adopts PII266, and internal memory 128M is based on the Window98 operating platform.
The sound signal sensing method of the PLASMA ARC WELDING molten bath perforation state of present embodiment is: at first uses the sample frequency of above-mentioned signal acquiring system, gathers the voice signal in the welding process in real time with 50kHz, and the input computing machine.The voice signal A algorithm that adopts the present invention to design is subsequently handled the data that deposit in the computing machine, and Fig. 6 is the process flow diagram with the software implementation algorithm.
Algorithm flow is as follows: read in the voice signal sequence s (n) that collects; Get and analyze rectangular window function moving step length i=1024, with s (n) segmentation M=s (n)/i-1; Give m, and the N assignment (m=1, N=4096).Enter circulation, the computational analysis window function
S (n) is made the windowing Fourier transform
To DWFT
s(m k) deals with
Judge m 〉=M, if vacation m=m+1 then repeats above-mentioned computing; If true, then withdraw from circular treatment.A (m) is carried out smoothing processing, promptly get A
s(m) signal, shown in Fig. 8 c, horizontal ordinate is the time among Fig. 8 c, and unit is s, and ordinate is A
sThe amplitude of signal.
When table 1 has been listed under the variety classes source of welding current condition soldering stainless steel, A
sThe critical value of the threshold value whether bore a hole in the molten bath of signal, molten bath transition state.
Table 1
| Transducing signal | The threshold value T whether bore a hole in the molten bath 2 | The critical value T of molten bath transition state 1 | ||
| Inverter type welder | The magnetic amplifier welding machine | Inverter type welder | The magnetic amplifier welding machine | |
| A s | 25～38 | 25～35 | 80 | 70 |
With the A algorithm voice signal is handled and to be obtained transducing signal A
sAfter, from table 1, find A corresponding to the inverter type welder stainless steel work-piece
sThe threshold value T whether bore a hole in the molten bath of signal
2The critical value T of (being 25～38) and molten bath transition state
1(being 80) according to the threshold decision criterion of molten bath perforation state, works as A
sSignal amplitude is higher than the molten bath transition state critical value T of setting
1, think that the molten bath is in the do not bore a hole perforation or the transition period transition period of or not of boring a hole at=80 o'clock; Work as A
sSignal amplitude is lower than the threshold value T whether bore a hole in the molten bath
2=25～38 o'clock, confirm as the molten bath and bore a hole, realized normal PLASMA ARC WELDING; And work as A
sSignal amplitude is lower than the critical value T of molten bath transition state
1=80 and be higher than the threshold value T whether bore a hole in the molten bath
2, judge that then the molten bath is puncherless state at=25～38 o'clock.Use A
sThe result of input molten bath perforation state is marked among Fig. 8 b, and wherein the AB section is the puncherless stage, and BC and DE section are transition period, and the CD section is the perforation stage.The structure that can see testing result and back side fluting workpiece conforms to the demonstration of molten bath perforation state.In addition, for the processing of giving voice signal provides synchronous reference signal, back of weld mounts phototriode 70 (model is 3DU33) as shown in Figure 7.The same moved further of phototriode and welding torch in the welding process, its output voltage signal with the sampling of 50kHz speed, is sent into computing machine with voice signal, and when molten bath perforation state changed, the output signal of phototriode had single order transitionization.A algorithm process result and the contrast of phototriode output voltage signal, match result is good.This detection technique perforation of sensing molten bath and puncherless state exactly are described thus.
Table 1 shows that welding machine type and welding variables all can cause the difference of aperture transducing signal threshold value, for this reason, needs in actual use to select suitable voice signal judgment threshold for use according to concrete welding implementation condition.
Claims (4)
1. the voice signal detection method of a molten bath for plasma welding perforation state is characterized in that, may further comprise the steps:
1) utilizes the sound microphone, obtain the voice signal s (t) in the plasma arc welding termination process, voice signal s (t) is gathered and be stored into computing machine in real time by signal acquiring system;
2) processing that the voice signal sequence s (n) that gathers is made the A algorithm is handled, and obtaining can be for the quantitative molten bath of the machine recognition transducing signal A that whether bores a hole
s
3) with A
sThe threshold value of whether boring a hole with molten bath given in advance compares, to judge the state of molten bath perforation at that time.
2. voice signal detection method as claimed in claim 1 is characterized in that, said voice signal is processed the A algorithm of processing, may further comprise the steps:
1) design analysis rectangular window function g (n-m), the voice signal sequence s (n) that computing machine is got access to makes discrete windowing Fourier transform (DWFT);
2) to the windowing Fourier transform DWFT as a result that disperses
s(m, k), do following processing:
F in the formula
1, f
2---the frequency of voice signal, f
1=0Hz,
f
2=100Hz draws A (m), and it is done promptly to get sound sensor signal A after the smoothing processing
s
3. voice signal detection method as claimed in claim 1 is characterized in that, the said molten bath threshold decision criterion of whether boring a hole is: set the threshold value of whether boring a hole in the molten bath and the critical value of molten bath transition state, work as A
sWhen signal amplitude is higher than the molten bath transition state critical value of setting, think that the molten bath is in the do not bore a hole perforation or the transition period of or not of boring a hole; Work as A
sSignal amplitude descends and when being lower than the threshold value of whether boring a hole in the molten bath, can confirm that the molten bath bores a hole, is normal perforate PLASMA ARC WELDING; And work as A
sWhen signal amplitude is lower than the critical value of molten bath transition state and is higher than the threshold value of whether boring a hole in the molten bath, judge that then the molten bath is puncherless state.
4. plasma arc welding sound signal collecting system in the method according to claim 1, it is characterized in that, by sound transducer, data collecting card, computing machine and relevant interface, and be stored in the computing machine corresponding sound signal collecting process software and form, wherein, voice signal is at first introduced the input end of sound transducer, the input terminal of the output termination data collecting card of sound transducer, and data collecting card directly inserts the associated socket of computing machine.
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|---|---|---|---|
| CN 00105933 CN1102477C (en) | 2000-04-21 | 2000-04-21 | Sound signal sensing method and system for the perforative state of plasma arc welding bath |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 00105933 CN1102477C (en) | 2000-04-21 | 2000-04-21 | Sound signal sensing method and system for the perforative state of plasma arc welding bath |
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| CN1267579A true CN1267579A (en) | 2000-09-27 |
| CN1102477C CN1102477C (en) | 2003-03-05 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102744493A (en) * | 2012-07-03 | 2012-10-24 | 广东技术师范学院 | Quantitative evaluation method of arc welding process stability based on electric arc sound |
| CN103240551A (en) * | 2013-05-23 | 2013-08-14 | 北京斯达峰控制技术有限公司 | Method, device and system for controlling numerically controlled welding speed |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102744493A (en) * | 2012-07-03 | 2012-10-24 | 广东技术师范学院 | Quantitative evaluation method of arc welding process stability based on electric arc sound |
| CN102744493B (en) * | 2012-07-03 | 2014-10-22 | 广东技术师范学院 | Quantitative evaluation method of arc welding process stability based on electric arc sound |
| CN103240551A (en) * | 2013-05-23 | 2013-08-14 | 北京斯达峰控制技术有限公司 | Method, device and system for controlling numerically controlled welding speed |
| CN103240551B (en) * | 2013-05-23 | 2015-06-24 | 北京斯达峰控制技术有限公司 | Method, device and system for controlling numerically controlled welding speed |
| CN107824989A (en) * | 2017-10-26 | 2018-03-23 | 大族激光科技产业集团股份有限公司 | The detection method and system of a kind of laser beam perforation |
| CN107824989B (en) * | 2017-10-26 | 2019-11-12 | 大族激光科技产业集团股份有限公司 | A kind of detection method and system of laser beam perforation |
| CN111082291A (en) * | 2019-11-19 | 2020-04-28 | 大族激光科技产业集团股份有限公司 | Monitoring device for perforation and fiber laser |
| CN113814586A (en) * | 2021-11-05 | 2021-12-21 | 泰尔重工股份有限公司 | Method for judging puncture state of laser cutting machine based on sound signal |
| CN113814586B (en) * | 2021-11-05 | 2024-04-09 | 泰尔重工股份有限公司 | Method for judging puncture state of laser cutting machine based on sound signal |
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