High speed carbon dioxide solders medium bath stability and welding line figuration

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Summary: Application has the fluid stability theory of free surface, the generation mechanism that solder of the hump when explaining high speed solders, pass the real time picture that forms a process to bath to collected pair of this theory to undertake test and verify. Theoretical analysis and test result all make clear, the frit drop that uses freedom to transfer transfers the form undertakes soldering, workpiece is in from beginning to end solder of electric arc heat below, when high speed solders, bath cannot cool in time, bath spins apparently, by disturb the oscillatory wavelengh that cause is big, when bath spin when reaching certain level, meet those who produce liquid metal miss the appearance that shrinks firmly with the neck, create hump solder line. Put forward on this foundation, can use short circuit to transfer what replace tall voltage to fall freely, the electric arc when using short circuit to transfer extinguishs what can reduce pair of bath periodicly to add quantity of heat, prevent bath to grow too and break firm. Test result makes clear, use short circuit to transfer the generation that solders to prevent hump solder effectively to, rise solder speed. Keyword: High speed solders the important segment that preface of figuration of bath stability welding line solders to be produced as industry, its machine speed to having decisive effect to total productivity. Manufacture efficiency to rise, enhance market competition ability, manufacturing company solders to rising speed raised more and more pressing requirement. But, solder of speed rise can bring a few different issues when soldering with groovy speed. Among them the mainest is difference of welding line figuration, occurrence solder path bites the phenomenon of the edge, when rate rises further, appear " hump " solder (Humping) [1, 2] . The generation mechanism that path of the solder when ever soldering to high speed CO2 in the author job in the past bites an edge undertook study [3] . In the article, will still solder with high speed CO2 for the object, right " hump " the generation mechanism that solder undertakes theoretical analysis and experiment study, the method that this one blemish appears to preventing on the foundation here undertakes trying. The form appearance characteristic of 1 hump blemish is alleged " hump " solder path, be point to welding line metal to go up along direction of welding distributing serious not all blemish of welding line figuration. Graph the exterior that the 1 hump solder that is a model, graph the 2 cross section photographs that for this solder, pursue among them 2a is hump " the peak supports " sectional, graph 2b is " cereal bottom " sectional. Can see, although welding line frit is deep He Rongkuan change is not big, but welding line metal is sectional produced huge change. Additional, notable is, of welding line of hump blemish edge distributing compare the pattern, because this can say the accidental change of condition and parameter does not cause this one appearance, decide by the special situation getting power of the bath when high speed solders however. Graph surface of road of 1 hump solder pursues the cross section that 2 hump solder the relation of figuration of 2 welding line and bath stability 2.

1 solder the stable condition of bath solders bath appearance and figuration of ultimate welding line are the result that bath place gets all sorts of outside force combined action, wait like tension of electric arc force, gravitational, surface. The characteristic of the bath when high speed solders basically is appearance slightness, bath freedom surface is big, right now exterior tension appears to the influence of welding line figuration highlight particularly. Application has the fluid stability theory of free surface, can the generation mechanism that solder of hump of better geographical solution. As qualitative analysis, can will solder bath the post of a paragraph of fluid that brief melt into keeps by exterior tension only, if pursue,3 are shown. Graph of 3 fluid column break firm principle to set fluid column surface to have one tiny disturb, set square of intensity of pressure to to point to liquid interior, intensity of pressure can write the liquid interior that goes up in sectional A and B for following forms [4] : (1)     (the PA in 2) type, PB -- liquid interior intensity of pressure; σ -- exterior tension coefficient; RA, RB -- free surface is in on welding line cross section advocate curvature radius; RA, RB -- free surface is in even if welding line is sectional those who go up advocate curvature radius. In the graph 3 in, set disturb wavelengh is λ , the radius when fluid column is balanced is A, be like λ / A is very small, criterion RA, RB is far be less than A, have RA of RA < < namely, RB of RB < < , be in liquid intensity of pressure to be able to be approximately in sectional A and B right now: (3)     (4) is in namely A is sectional cause negative pressure PA, in B sectional cause pressing PB, the liquid will flow to A from B, reduce thereby disturb the liquid appearance that create is out of shape, make fluid face restores to balance position; But be like λ / A is very big, criterion RA, RB is ambitious at A, because this is in type (1) , (the σ in 2) / RA, σ / RB but oversight, namely type (1) and type (2) is approximately: (5)     (6) as a result of RAPB, create difference of an intensity of pressure in liquid interior so, the liquid will flow to B by A, make RA continues to reduce, RB continues to increase, consequently difference of intensity of pressure increases further, liquid flow is quickened, cause fluid column to produce a neck to till be defeated,shrink in sectional A place. 2.

The bath when 2 high speed solder loses sure account soldering normally below speed, bath is wide and short, volume is minor, its natural frequency is taller, in disturb likewise below the condition, oscillatory wavelengh is small, because of this λ / A is very small, won't produce afore-mentioned breaking commonly firm phenomenon; And when high speed solders, bath spins apparently, and width is reduced, in the meantime, because volume of liquid state metal is larger, natural frequency is inferior, by disturb the oscillatory wavelengh that cause is big. Because of this λ / A increases significantly, when bath spin when reaching certain level, meet those who produce liquid metal break shrink firmly with the neck the phenomenon that defeats, create hump solder line. 3 bath are broken firm the experiment test and verify that produces a course with hump is test and verify afore-mentioned hump produces mechanism, built image of bath of a real time to collect a system to fashion a process in order to observe what hump solder CO2 solder is medium. Pass logical choice filter, the peak value spectral line of spectrum of escape CO2 electric arc, can get better bath picture. Graph the bath image when a group of 4 high speed that gather to use this system solder. Fashion a process from what a hump can see clearly in the graph. A new bath appears and spin gradually (A ~ B) . In picture B, can see bath appeared slight curvature changes, this one change expands ceaselessly (C) , bath occurrence neck shrinks (D ~ F) , till final bath metal is least part above all caky, a new bath is formed again, repeat above process (G ~ H) . Bath is right now hind had collected many liquid metal, cause hump, this one process and go up the theoretical analysis of the section is consistent. Graph the formation of 4 hump process (I=300A, u=31V, v=2.

The measure of stability of the bath when 2m/min) 4 raises high speed to solder can see from theoretical analysis and test result, high speed solders in a when produce hump solder line main reason is bath is excessive spin make bath is broken firm. And the cause that causes bath to grow too, because solder,be of speed raise need to use bigger solder electric current. According to conventional technology, solder in what what when big electric current solders, match voltage is tall also, the frit drop that because this is,uses freedom to transfer transfers the form undertakes soldering. Below this kind of circumstance workpiece is in from beginning to end solder of electric arc heat below, hot input amount is large, in very tall solder below speed, bath cannot cool in time. When than convention speed solders, so the length of fused condition metal grows more, generation bath breaks firm possibility to also rise greatly. Be based on this kind of reason, can use short circuit to transfer what replace tall voltage to fall freely, because the electric arc when crossing passes to extinguish what can reduce pair of bath periodicly to add quantity of heat in short circuit, prevent bath to grow too and break firm. Of course, the stable short circuit that should come true to fall in bigger electric current transfers need to soldering the output of equipment undertakes be controllinged accurately. What the author uses proper motion to develop is odd welder of control inversion CO2 is opposite a machine weaveform use short circuit to crossed the feasibility that crosses implementation high speed to solder to have a test, obtained apparent effect. Graph the 5 bath image when undertaking to use short circuit to transfer high speed solders, with the graph 4 contrast can see, transfer in short circuit below the form, bath length is reduced apparently, because this did not appear,liquid misses firm appearance. Of this experiment solder the effect is shown 6 times like the graph, got sectional and even, figuration is better solder contact. Graph the 5 bath configuration when using short circuit to transfer (I=300A, u=24V, v=2.

2m/min) pursues 6 use short circuit to transfer the effect that undertakes high speed solders 5 conclusion   (1) uses the fluid stability theory that has free face, can the generation mechanism that solder of the hump when better land explains high speed solders. (Of the bath when 2) high speed solders excessive spinning is to cause bath to break firm the main reason that forms hump solder line. (3) uses short circuit to transfer form, reduce length of the bath when high speed solders effectively, prevent to produce hump limitation. CNC Milling CNC Machining