The analysis of error of processing of pattern company electric spark

Summary: The electric spark in listing pattern company processes the common error of existence, undertook in the light of these errors the technology is discussed, to pattern company electric spark treatment has direct sense. Keyword: Electric spark treatment; Fixed position; Electrode material; Electrode shrinks to the limit of one's capacity; Technique; Treatment of 1 foreword electric spark is a kind of when the mould makes main technique, in noting model moulding to build especially, be to producing the effect that hold the balance more. The craft level that still has many pattern companies at present is not quite perfect, the electric spark that a few errors that be in put to often cause mould part in craft machines requirement of the precision that short of books, efficiency. Later development machined common error to undertake more detailed analysis to the electric spark in pattern company. The common error that 2 electric spark process 2.

The precision that the error electric spark of 1 location method machines is controlled and assure to depend on greatly fixed position precision. In the Z axis treatment that uses normally, axis of X, Y assures model antrum position requirement, z axis makes sure the deepness of a treatment antrum asks. The method that implements electric spark to machine fixed position has a variety of, the location method that uses electrode and workpiece to undertake osculatory perceptive (graph 1) in the mould the enterprise is used extensively. Graph 1 electrode and workpiece contact perception to locate this is planted directly location method is relatively simple, it is operation personnel is very familiar. But we can discover, if the precision demand of electric spark treatment is very high, requirement of fixed position error cannot is more than 0.

01 ㎜, like the haing husband slide block in plastic model, fluctuation of modular benevolence to closing, insert the treatment that wears place to wait, these use afore-mentioned methods to will have very great difficulty below the circumstance, assure stable fixed position precision hard, because fixed position out of tolerance causes a part,repair repeatedly, the circumstance that discard as useless happens from time to tome. The perceptive performance that handlers often blames a machine tool is bad to perhaps locate precision is not tall. Actually v/arc be on the throne of current machine tool of electric spark treatment moves the precision of the respect is quite tall, the circumstance that occurrence fixed position forbids is namely on the method that chooses location existence error. Use electrode and workpiece to undertake touching a limit directly, because osculatory area is larger, of the burr on electrode or workpiece, existence subtle and sundry, the element such as the flatness of electrode and workpiece, parallelism, verticality affects fixed position precision, although workpiece and electrode are brushed very neatly,also assure hard 0.

The fixed position precision of 01mm. To workpiece (electrode) abnormity or electrode are too big (too small) reach precision to ask to comparative for tall treatment, have and use indirect location method only, use fiducial ball to have indirect fixed position namely (graph 2) , because method of this kind of location is used is point contact, the error can be eliminated inside the biggest range. Graph indirect fixed position still has 2 fiducial balls at present the method that many pattern companies do not know to use fiducial ball to locate. Use fiducial ball to have fixed position not only assure precision easily, and in workpiece appearance complex case falls, in can realizing cent conveniently; Electrode looked for central process to avoid electrode to make the shift of greater distance to fiducial ball, saved operation time; To the circumstance that many workpiece machine, in needing to use electrode for many times to divide, should divide to fiducial ball only second in can, saved many operation time, the advantage in much electrode treatment particularly apparent. Of course, here is not the advantage that emphasizes using method of fiducial ball location blindly, for not much to amount of a few the treatment that general precision asks, workpiece, electrode circumstance, to improve work efficiency, still use electrode to have fixed position directly normally. The precision of the methodological requirement electrode that uses fiducial ball fixed position additionally and workpiece datum plane wants very tall, can produce bigger fixed position error instead otherwise. 2.

Of the error electrode material that 2 electrode material chooses choose the effect that matters to discharge directly, greatly, of material choose appropriate, decided discharge rate, machine the final circumstance of precision and exterior surface roughness. The effective demand that should machine according to different type mould, what specific aim ground has stuff is choose. The electrode data that electric spark processes basically has tungsten alloy of red copper, black lead, copper. When company of a lot of patterns is choosing electrode material, have a consideration rarely, same habit chooses size electrode akin electrode material. This kind of practice won't discover its corrupt practice in be machined normally, but can discover clear problem in ultimate treatment, affect the result that electric spark machines. If all electrode material choose red copper, often can blame machine tool loss when tall nicety is machined so too big, need uses a lot of electrode to undertake machining, large electrode also chooses red copper, bring about time of treatment place cost a lot of, cost is very high also. This is the error that material of the electrode in electric spark treatment chooses. Material of logical choice electrode, can have a consideration from following respect: Electrode machines figuration whether easily; The discharge of electrode machines function how; Quality of treatment precision, surface how; The cost of electrode material is reasonable; The weight of electrode how. Below a lot of circumstances, the electrode material with different choice has the place of its actor bad each, this captures the crucial essential factor of treatment with respect to the requirement. If undertake high accuracy is machined, that is about to abandon the consideration of electrode cost of material, if ask to undertake high speed is machined, that is about to will machine precision to ask to lower. Red copper can acquire stable treatment position more easily, low caustic compasses is used to allow to be able to be obtained in finish machining clear-cut model antrum, treatment surface is bright and clean degree tall. But because itself material melting point is low, unfavorable bear bigger current density, cannot exceed the treatment of 30A electric current commonly, can make electrode surface serious otherwise damage, chap, the influence machines the effect. Hot coefficient of expansion is bigger, machining deep narrow muscle part, the local high temperature of the generation below bigger electric current makes electrode happening is out of shape very easily. Red copper electrode adopts the treatment requirement of small loss normally, the average electric current that machines as a result of small loss is lesser, its productivity is not tall. Black lead electrode is special apply to treatment corrode to divide an amount bigger model antrum, rough machining of small loss, high speed can come true below circumstance of large area treatment, its distinct treatment advantage can be produced in be being machined like the electric spark that waits for a mould in model of large and plastic mould, forging die, Die Casting. Good mechanical strength is had below high temperature, hot coefficient of expansion is small, suit to be opposite very much narrow seam undertake high accuracy is machined. Because its weight is light, commonly used the production at large electrode. Electric performance is good, treatment rate is rapid, can save many discharge time, price is the 1/2 that copper expects commonly. Its defect is to be in finish machining discharge stability is poorer, transfer easily to discharge to electric arc, can choose the treatment condition with bigger loss to machine only. Machine imperceptible face surface roughness to be differred slightly, fall off easily in treatment, drop broken bits. Electrode of the black lead that make wants special treatment machine. Material of cupreous tungsten alloy is used rarely in be machined normally, the electric spark that reachs a few special situations in tall exact pattern only just is used in treatment. Because contain tungsten the volume is high, resist effectively the loss when electric spark is machined, can assure extremely small electrode loss, in extremely difficult treatment the condition falls to also can realize stable treatment. Defect is the price costly, material origin is difficult. Treatment electron receives plug-in unit kind when high accuracy mould, the appearance to subtle part (be like profound complex and straight wall aperture, small-sized antrum) the requirement is very strict, this is about to beg loss of the electrode in treatment must dinky, choosing cupreous tungsten alloy to make electrode is the main demand of processing technique. Cupreous tungsten electrode is aimed at wolfram steel, high-carbon steel, high temperature resistant exceed hard alloy metal, because common electrode loss is big, rate is slow, cupreous tungsten electrode is first selection material. 2.

3 electrode shrink when the error electric spark that to the limit of one's capacity chooses is machined polar an existence scintilla clearance, give the measure that accords with a requirement for treatment, shrink to electrode put proper measure to machine. Electrode shrinks the size of to the limit of one's capacity is right quality of efficiency of the dimension precision of treatment, profile modeling precision, treatment, surface is influential. Most pattern company withdraws in what choose electrode is when to the limit of one's capacity according to fixed mode, if normally rough machining electrode shrinks,put unilateral 0.

2 ㎜, finish machining electrode shrinks put unilateral 0.

07 ㎜. If the area of electrode is very large, because electrode shrinks,to the limit of one's capacity slants small and bigger discharge parameter cannot be chosen in restricting electric spark to machine, reduced treatment efficiency, this is electrode shrinks the error that to the limit of one's capacity chooses. Electrode shrinks of to the limit of one's capacity choose the factor that should consider many sided. Electric spark treatment has translation treatment and not translation machines two kinds of means, machine tool of numerical control electric spark can use translation treatment commonly, and if machine tool of traditional electric spark did not install translation head to cannot undertake translation is machined. Electrode of means of these two kinds of treatment shrinks of to the limit of one's capacity choosing is distinguishing. When using translation to machine, if the scintilla clearance of place generation is less than electrode,shrink to the limit of one's capacity, the dimension that treatment comes out will be less than mark fiducial value. Contrary, electrode shrinks the dimension after to the limit of one's capacity wants hour of meeting to make machine than actual scintilla clearance is more than mark fiducial value. Because this correct affirmatory electrode shrinks,the size of to the limit of one's capacity is the premise that assures to machine dimension qualification. What affirmatory electrode shrinks to the limit of one's capacity is large hours to want to inspect treatment place is different and reasonable choose. Treatment place divides plastic mould to be mixed for structural sex place commonly shape place. Structural sex position rises in the mould cooperate, the action such as fixed position. The treatment surface surface roughness of these place does not have strict requirement, but requirement measure is machined reach the designated position, the dimension after assuring to machine accords with a requirement. In decide these place scintilla the size of the scintilla clearance of actual generation when treatment is being taken when size. Shape place is to be used shape directly model place. The treatment dimension of this kind of place and exterior surface roughness have corresponding demand. Electric spark machines shape the mark of grain of methodological purify scintilla that place uses polishing after treatment is finished commonly is achieved book exterior surface roughness to ask, be in so decide this kind shapes place electrode shrinks surplus of accurate and affirmatory polish answers when to the limit of one's capacity. General polish surplus takes 4Ra+0.

005mm controls (Ra: The exterior surface roughness that electric spark treatment finishs is worth) , in computation electrode shrinks actual scintilla clearance and polishing surplus the sum are taken when to the limit of one's capacity. Craft of electric spark treatment is to use the electrode of different measurement to use different electric plan to allow commonly by thick complete treatment to essence of life. The dimension after treatment basically decides the control at finish machining. Scintilla of certain precision work the electric parameter condition that big small Shi Yingxian has considered to book exterior surface roughness to want to choose to achieve, the size that makes clear clearance of this condition scintilla decides electrode shrinks again to the limit of one's capacity. Shape the scintilla of place finish machining take odd side commonly 0.

04 ～ 0.

08mm, structural place takes odd side 0.

02 ～ 0.

06mm. Scintilla of affirmatory rough machining with considering to machine speed is mixed when size for finish machining obligate proper surplus is a standard, take odd side commonly 0.

15 ～ 0.

25mm. When using electrode translation to machine, the dimension precision of treatment decides at shrinking to discharge clearance, electrode peace of to the limit of one's capacity uses the control of the quantity. Because the bulk of smooth momentum can control, can move a smooth momentum according to the size of discharge clearance so, can control the dimension of treatment easily, electrode shrinks the size of to the limit of one's capacity is OK also relatively a few bigger, be opposite especially for finish machining, and can come according to a few particular cases choose neatly. It is commonly in rough machining need not translation treatment, electrode shrinks to the limit of one's capacity takes odd side 0.

15, 0.

3mm. Finish machining is used multistage treatment condition improves the condition that discharge bits with the method of translation, obtain stable treatment, can obtain the exterior surface roughness with flank and evener underside. Of electrode shrink to the limit of one's capacity is taken commonly 0.

05, 0.

15 Mm. Be being measured because of translation in common treatment is not very big, won't influential to machining profile modeling precision. But in accurate treatment, because choose the appearance of translation means and treatment appearance to have a difference, to raise profile modeling precision, electrode shrinks to the limit of one's capacity cannot too big, take unilateral commonly 0.

05 Mm is the following. Affirmatory electrode shrinks the treatment performance that still should consider to machine place in detail when the size of to the limit of one's capacity. If be in via kind below the case with good cuttings pick-up, form discharge not easily 2 times, electrode shrinks to the limit of one's capacity is somes small more desirable; And blind aperture kind because cuttings pick-up is not very suitable,machine, the chance that discharges 2 times is more, electrode shrinks to the limit of one's capacity should be taken a few bigger; When large area is machined to achieve rapidder treatment rate, electrode shrinks to the limit of one's capacity is somes big more desirable; The discharge clearance in the treatment that mix pink compares the discharge space that uses treatment of average job fluid to want a little bit big, electrode shrinks to the limit of one's capacity is somes big more desirable; Accurate treatment relatively the electrode that machines normally shrinks to the limit of one's capacity wants a few smaller. But want to notice, to the electrode of thin, pointed appearance, shrink to the limit of one's capacity should choose a little bit small, because this kind of treatment cannot choose big treatment condition, can make electrode is machining medium happening to be out of shape otherwise, additionally bigger electrode shrinks the intensity that to the limit of one's capacity also reduced electrode. 2.

At present the application of machine tool of numerical control electric spark in pattern company popularizes the error of 4 technique more and more. By use tradition electric spark machine tool develops some manufacturer to use machine tool of numerical control electric spark in pattern company, because these enterprises are used the influence of traditional machine tool for long, had formed experience of a lot of treatment. But actually, because the operation of the operation of machine tool of numerical control electric spark and machine tool of traditional electric spark is different, this caused the presence when pattern company is using machine tool of numerical control electric spark a lot of errors. Machine tool of traditional electric spark can use Z axis to undertake perpendicular servo feed is machined only commonly. And at present great majority accuses electric spark machine tool to be able to realize treatment of transverse treatment, much axis linkage. But these functions are in pattern company and did not receive very good application, it is OK that a lot of handlerses think to want to be able to machine the spare parts can machine the spare parts only, the habit uses conservative Z axis treatment. Actually, if can fill the function that distributes brandish machine tool, it is OK marked improvement machines quality, raise those who machine efficiency. The graph shows those who be the one model that note model 3 times to shape mold insert, there is thinner, deep glue all around. If this place uses treatment of Z axis servo, because partial discharge area is small,meet, treatment deepness is big, the phenomenon with not stable discharge can produce in machining a process, then brings about electrode feed to show answer repeatedly retreat, treatment rate is slow, electrode loss is bigger, exterior surface roughness is inhomogenous wait for unusual problem, cannot satisfy treatment requirement. If pass,improve technique, use the transverse servo function of machine tool of numerical control electric spark, make electrode makes transverse servo treatment, can solve afore-mentioned problems, obtain clear improvement the effect, machine speed to be able to rise than using Z axis servo to machine especially multiple. Graph 3 transverse servo machine a graph 4 it is to use electric spark treatment to keep clear of the part of cutting tool R that after cutting is machined, remains, it is commonner treatment type, say again " clear part is machined " . When having this kind of treatment, if use the method of linkage of axis of X, Y, Z3, namely inclined to treatment, because machine place area,can avoid small and the phenomenon that produces discharge to be not stabilized. Graph horn of 4 inclined Xiang Qing machine 3 last words at present company of a few patterns lacks an innovation on technique, lack the understanding of new to the outside technology, this makes enterprise cannot the production level that whole raises a pattern. The common error that above paragraphs processes to pattern company electric spark undertook the technology is analysed, the hope can bring suggestive help to relevant enterprise. Additional, the technique that current electric spark processes had obtained very great progress, if machine tool of electric spark of advanced numerical control emerges in endlessly, can realize efficient accurate treatment; System of the fast location that hold clip (EROWA, 3R) do not need to undertake repetition corrective, fixed position to electrode and workpiece, improved the operation efficiency of treatment greatly; The treatment that mix pink makes the lens face treatment of large area becomes reality, etc. Below the case that in the mould it is thus clear that production technology develops quickly, pattern company should the production demand according to oneself, the quantity is ordered personally make a sound technology, go improving ceaselessly, make the enterprise is in incincible position in the tide with intense competition. CNC Milling