Cut of silk thread of don't go yet electroanalysises the analysis of rustily discharge condition and control
- source:LENA CNC Machining
It Affects Not Only The Surface Accurcy And Mechanical Strength But Also The Cutting Speed.
The Main Causes Leading To Electrolysis In WEDM Are Anodic Dis Solutionand Dielectric Dissociation.
The Present Work Makes A Study On How To Counteract Them.
Also, act The Electrolysis During The WEDM of ～ of It Develops An Anti-electrolysis Power Supply To Directly Counter.
Keywords: Overview of WEDM Anodic Dissoluation Dielectric Dissociation Electrolysis Discharge1 is machined as a result of cut of electric spark line (WEDM, wire-EDM) have the effect that does not suffer treatment material hardness, did not machine stress, treatment precision is tall it is OK to can machine complex form workpiece to reach undertake nobody operate the advantage such as treatment, accordingly, line cut treatment is considered as current a kind of main metal machines a method. In process of treatment of cut of silk thread of don't go yet, the energy that the electrode silk that connects with power source produces through discharge bumps workpiece surface to undertake cutting to workpiece. Workpiece must be conductor, happen to prevent to machine condition of the short circuit in the process, there must be insulation job current to pass between electrode silk and workpiece, such ability have appropriate condition to produce discharge, normally liquid of this kind of insulation is used go ionic water. It has cost to catch fire lowly, not easily, the advantage of facilitating safe production. Below same pulse energy, undertake in water cut can improve treatment productivity discharging. Reduce electrode silk loss and improvement to be machined the exterior quality of workpiece, but, when the sky that is added on discharge clearance when uses pulse power source carries pulse voltage to contain dc heft, undertake cut of electric spark line can arise in water electroanalysis rustily discharge condition, if electrode silk and workpiece can observe apparently,water electroanalysises and zincous metal atom dissolves phenomenon. This is brought about by the out of control of electric corrode process of treatment workpiece surface, exterior precision is damaged; Raised workpiece appearance rustily or oxidation, the mechanical intensity of abate workpiece. Additional, what solution of water and electricity arises is hydric reached oxygen to comprise " volatile " aeriform mixture, explosion produces in the meeting when scintilla discharges, make machine workpiece surface to produce limitation, attaint electrode silk, fasten electrode is mobile, reduced treatment precision. Electric spark of silk of 2 don't go yet electroanalysises in line cut process the analysis of rustily discharge condition is online in cut treatment process, electroanalysis rustily discharge position is very general. This kind of headachy discharge condition basically is concerned with the electric current that has circulated working fluid, if pursue 1 with the graph 2 are shown. In the graph 1 in electrode silk and negative pole of pulse power source are linked together, workpiece electrode namely positive pole and anode of pulse power source are linked together. Graph 2(a) and graph 2(b) show the mechanism weaveform of condition of the discharge in line cut process. Give out in the graph add in the voltage V that changing along with time on negative electrode and the I of discharge electric current that pass in treatment clearance midstream. Pulse power source gives out voltage of a pulse in every cycle, in planning discharge course voltage V achieves Va of voltage peak value, and discharge instant clearance two end voltage drop arrives Ve of discharge clearance voltage. The end clearance as discharge two end voltage drop V arrives 0 bend over. In the meantime, electric current has flowed to be Ie between the electrode in discharge process, electric current of the clearance after discharge ends is Ir. Graph 1 electroanalysis sketch map of rustily discharge condition pursues voltage of the clearance in process of 2 lines cut and voltaic weaveform pursue above all, in machining a process, zincous metal atom dissolves is generation electroanalysises rustily main reason. Because leach be soiled is between electrode, and the electrical conductivity of water is very low, it is commonly a few Xi Menzi arrives every centimeters a few Xi Menzi every centimeters, then clearance voltage amid is formed " leakage current " Ia. The metallic atom ionization that below action of leakage current I workpiece surface dissolves releases metallic cation and free electron, following type place show: Next, solution of water and electricity also can be accelerated electroanalysis rustily speed. Although water is a kind of weak electrolyte, but it can be decomposed piece ionic H+ and anion OH- , following type place show: Below the in electric field action in machining a process, ionic H+ and anion OH- part to move to cathode and positive pole, near electrode silk face, after pH indicator H+ gets an electron, release hydric and those who because discharge causes explosion,increased is dangerous. Additional, space of the discharge when treatment is very little, the metallic cation Mn+ below zincous dissociation has very great opportunity and hydroxyl ion reaction to generate M(OH)n sedimentary deposit is in workpiece surface. Such, the mechanical intensity of workpiece and exterior precision will suffer an effect. Be a few hours commonly as a result of handling time or a few days, and workpiece often is steel, accordingly, electroanalysis what deposit of hydrate of deliquescent, zincous metal and treatment process make the zincous metal that rustily discharge produces is hydric will be become not sufferable by phenomenon of scintilla ignition explosion. Because it destroys precision of treatment metal surface not only, change form of metallic surface geometry, the mechanical intensity of abate workpiece, meanwhile, in still destroying all is in to machine a process, contact with water, can electric machine tool each parts, be like: Workbench, clamping apparatus is mixed electric conduction piece. After treatment ends, rustily to be being electroanalysised metal workpiece undertakes finish machining is achieved far from possibly expect the result, additional, must be measured carefully so that undertake to machine tool component and add and corrective. Accordingly, since electric spark treatment comes out, manufacturer and user search control to electroanalysis with respect to effort the effective prescription clever medicine of rustily discharge condition. Control of treatment of electric spark of cut of silk thread of 3 don't go yet electroanalysises the method of rustily discharge condition is on the foundation that draws lessons from forefathers, developed control of cut of silk thread of a kind of don't go yet to electroanalysis the power source device of rustily discharge condition, if pursue,3 are shown. Its are applied to arrive from rough machining in the different plan standard treatment of finish machining. It is the device of power source of cut of electric spark line in the tradition a group of control are added to electroanalysis on the foundation system of rustily discharge state. As typical zincous protector, this system can control power supply of traditional line cut the because electroanalysis,rustily discharge produces job juice in device electroanalysises reach a series of undesirable phenomena such as ionization of zincous metal atom. Online cut machines the workpiece in loop to serve as positive pole, in the meantime, in electroanalysis in rustily control circuit. Workpiece is used again as cathode. Electroanalysis there is one or more to electroanalysis at least in rustily control circuit control electrode, its number is decided by the complex degree of workpiece. In the graph 3 in, use two to electroanalysis control electrode, their dip is in water or spray water ceaselessly on its, in the meantime, control voltage is added between they and workpiece. In working process, in electroanalysis Ia of electric current of control loop generation and Ie, these two electric current use what Ia and Ie of discharge electric current generate leakage current of loop of quits treatment discharge to electroanalysis rustily discharge. Its eliminated conventional treatment as a result in the method because electroanalysis,the zincous metal of rustily generation dissolves and working fluid electroanalysises phenomenon. Graph 3 control electroanalysis control of cut of silk thread of don't go yet of sketch map of power source of control of rustily discharge state electroanalysises field effect is in charge of semiconductor of oxide of metal of MOSFET(of the nominal power of locomotive in system of power source of rustily discharge status) as switch component. The E of direct current source with identical amplitude and E(100 ～ 150V) pass power MOSFET M1, M2, M3, M4 and R1 of current limliting resistor, R2, R3, R4 to increase working tension electrode silk, workpiece and AE(to electroanalysis directly rustily control) between electrode. Con2 of controller of M1 of controller Con1 control, M2; controls M3, M4, the pulse signal that they output is in phasic on each other differs 180 ° . To get used to different treatment material and treatment process, controller Con1 and controller Con2 are mixed to electrode silk the arteries and veins between workpiece and AE electrode is reached between workpiece wide undertake modulatory respectively with the signal between arteries and veins. Detect circuit K1 and detect circuit K2 detects respectively the voltage signal between AE electrode and workpiece and workpiece and electrode silk machines condition signal and control report to liberate electric state signal namely, these two kinds of signal are in controller Con1 and controller Con2 MOSFET of voltaic attaint power passes in machining a process to prevent with M1 of the control after giving signal to have operation beforehand, M2, M3, M4, with voltaic sensor CK detects the voltaic signal that processes a process, also assured to machine the stability of the process thereby. The 3 ～ that here value of block of the R1 in circuit, R2 is R3, R4 4 times, such, make the absolute value of voltaic Ia and Ie does not exceed leakage current Ia and Ie of discharge electric current. Otherwise, from AE electrode deliquescent metallic cation goes to deposit workpiece apparently, not only short of control electroanalysises rustily purpose, affected the exterior surface roughness of workpiece and exterior precision instead. Control of cut of silk thread of don't go yet electroanalysises the function index of power source of rustily discharge status is: Arteries and veins is wide adjusting range from 1 ～ 100us, the adjusting range between arteries and veins from 10 ～ 1000us, the smallest occupy empty coefficient for 0.
Electric current of 1%; discharge peak value is 50A, voltage of discharge peak value from 100 ～ 150V between adjustable. To restrict actual corrosion of metals, collect appliance to have tall anti-corrosive the metal of ability regards AE electrode as material, be like: Stainless steel, titanium, black lead and exterior besmear have the material of anticorrosive layer to wait like platinum. 4 conclusion the article discussed cut of silk thread of don't go yet to machine electroanalysis in the process the fundamental of rustily discharge condition, developed control to electroanalysis the power source device of rustily discharge condition will control treatment process to electroanalysis rustily discharge condition structure of this power source is simple. Performance/price ratio is high, do not have an influence to machining speed, its are had in workpiece genteel the characteristic that has two-way electricity, this comes true through another support system is being added in conventional treatment power source. In working process, control electroanalysises electric current is smaller than machining electric current normally, because this can achieve good treatment result. The voltage weaveform in its job process sees a picture 4. The clearance voltage that discharges normally for WEDM partly on is undee, arteries and veins is wide for 8us, the part falls to electroanalysis for control for 15us; between arteries and veins the voltage of rustily discharge condition is undee, its arteries and veins is wide for 4us, 20us is between arteries and veins; Can see, control electroanalysises rustily circuit has shed very small control electric current, because can see from its voltage weaveform,make an appointment with those who have 20V to press fall. This control electroanalysises better land completed plant of power source of rustily discharge status rustily to electroanalysising control. The exterior precision of workpiece and mechanical intensity and look of conventional treatment method are very more than rising. Anyhow, regard a kind of new production as the method, control electroanalysises device of power source of rustily discharge status has main effect in lieutenant general of treatment of cut of high accuracy line, its application scope will be more wide. The graph discharges when 4 normal treatment clearance voltage and control electroanalysis rustily voltage is undee CNC Milling