The mould is made in electric spark machines unusual problem and analysis

The Whys Were Analyzed And The Method To Prevent Was Explored.

It Can Be Some References To The Upgrading Of EDM.

Key Words: Treatment of electric spark of foreword of EDM; Mould Quality; Problem; Whys; Countermeasure 1 is made in the mould in it is very important technology segment, make in plastic pattern especially in more important. Mostly plastic pattern spare parts uses electric spark treatment to complete final precision work normally, the assembly that machines finished quality to affect mould part directly function or shape precision. The unusual issue that treatment appears is small create a few needless processing techniques, cause workpiece whole to discard as useless again, lengthened a mould to make cycle, increased a mould to make cost, reduced mould quality, because this is on guard,produce treatment unusual problem has important sense. The quality problem after machining unusual problem to include to machine medium abnormal phenomenon and treatment. The unusual problem with common treatment of 2 electric spark and analysis (dimension of actual measurement of place of the treatment after treatment of 1) mould spare parts is finished is unqualified. The precision that the place that with electric spark treatment finishs can achieve normally is 0.

005mm left and right sides. The treatment precision requirement that place differs in mould spare parts is different, a few precision ask control of tall place dimension public errand is very strict. If machine dimension to not be inside tolerancepublic errand limit, it is unqualified dimension namely. Unqualified dimension has be more than the biggest limit dimension and be less than size of the smallest maximum. The factor that affects treatment dimension size has the following kinds: A.

Electrode size shrinks the influence of to the limit of one's capacity. When electric spark 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. Of electrode shrink put dimension aborning to call electrode to shrink to the limit of one's capacity. When treatment, the scintilla clearance of actual generation and electrode shrink the does not match will immediate impact to machine dimension precision of to the limit of one's capacity. When using electrode 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. When using electrode translation to machine, 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, make clear the 1 unoccupied place size between this condition scintilla to decide electrode scintilla again size. Shape the scintilla of place finish machining it is odd side commonly 0.

04, 0.

08mm, structural place is 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, scintilla take a standard to be worth momentum of peace of subtractive scintilla clearance, scintilla of the electrode in finish machining take odd side commonly 0.

12mm left and right sides. Affirmatory electrode scintilla the treatment performance that still should consider to machine place in detail when size. If be in via kind below the case with good cuttings pick-up, form discharge not easily 2 times, the scintilla gap look of generation is comparative and lesser, and blind aperture kind because cuttings pick-up is not very suitable,machine, the chance that discharges 2 times is more, and make scintilla clearance greatens. Big electrode shrinks to the limit of one's capacity is lesser electrode shrinks to the limit of one's capacity is relatively a few smaller. Energy of the discharge when discharging because of big electrode distributings even, the energy when small electrode discharges is centered. B. Pilot of real measure, smooth momentum affects electrode. When using electrode translation to machine, the measure that the real measure of electrode completes to machining place has conclusive effect. In scintilla of correct affirmatory electrode later, should use reasonable treatment method to assure to make the precision of electrode. When using electrode translation to machine, the control of smooth momentum has conclusive effect to machining dimension. Should the size according to dimension of electrode actual measurement, decide correct smooth momentum will assure to machine dimension to accord with a requirement. C. Electrode is corrective the influence of precision. The corrective precision of the dimension after treatment and electrode has very big concern. The perpendicular and planar umbriferous area that the corrective deviation of electrode can make its are machining feed direction increases, the dimension that makes its machine place is more than normal value. Because this is put in the flank clearance after be being machined with small electrode commonly,compare the situation with the flank largish clearance after be being machined with big electrode. Because the corrective precision of small electrode is impossible,have big electrode tall in that way. The corrective precision that assures good electrode is electric spark treatment the segment with begin phase the most important, it is one of fundamental conditions that assure to machine dimension qualification. D. Electric parameter adjusts the influence of the element. Electric parameter adjusts in mattering to treatment directly actual scintilla size. Each all can affect scintilla space size that changes electric parameter condition. The most apparent to scintilla clearance influence is electric current, as electric current also increase scintilla clearance accordingly. The influence of pulse width also is such. Of pulse clearance add congress to make scintilla clearance decrescent, but action is not apparent. Parameter also affects scintilla in indirect ground related other size. Because this is adjusting,must choose when electric parameter reasonable, the effect that can produce to machining dimension should be cleared up when changing electric parameter. E. The influence of loss of the electrode in treatment. Machining the inevitable existence electrode loss in the process, the dimension that electrode loss makes treatment is finished is less than mark fiducial value. (reason of abnormal loss of too big electrode is expatiatory below) the dimension that must control good electrode loss correctly to assure to machine accords with a standard. F. Machine deepness pilot influence. The deepness that machines feed direction in machining dimension is a particularly important measure. The control precision of deepness is concerning to machine dimension eligible. Affecting deepness to control the element of precision is the to knife precision influence before treatment above all. Be opposite the existence between electrode of Dao Shiru fruit and workpiece is sundry, can make produce deviation to the knife, the deepness that can make treatment is finished normally is less than mark fiducial value. Be in so polar to must assuring when the knife between clean. It is the influence of the mental allowance of obligate next. Size control of treatment place lateral decides the scintilla at electrode. And the obligate of the depth size that deepness control decides to want to machine to place at treatment. Obligate measures choose with electrode scintilla choose a principle identical. It is the influence of fiducial to the knife precision again. Electrode is used must be to the place of the knife those who make clear is fiducial, level off of datum plane Ying Guangjie. Notice in rough machining electrode heats up bulgy influence even finally, make its lengthen and be the surplus of finish machining obligate more than, make machine deepness to slant deep, repair when occurrence finish machining not only phenomenon. (2) machines off quality of surface of the place that finish. Unusual problem has exterior quality commonly carbon deposit, surface roughness does not accord with heavy panel of layer of metamorphism of requirement, surface. These 3 kinds of problems are aimed at below concrete analysis. A.

Carbon deposit. Carbon deposit is exterior quality unusual the most serious problem, produce ruinous result to mould spare parts. It is the child with the unusual discharge in electric spark treatment. Causing the main reason with unusual discharge is electric regulation the choice is undeserved. General carbon deposit happens in finish machining, because space of the discharge when finish machining is little, cuttings pick-up is not easy. Because this is adjusting,want to be a standard in order to observe discharge condition is stabilized when electric parameter, in discharge not stable circumstance falls, should reduce discharge time short, carry knife height increases, pulse width is reduced, pulse clearance increases, servo pressure is reduced etc. In rough machining, in attention of treatment area hour peak value electric current has not wanted big. Also have very big effect to oil next. Force of the means pouring oil of impropriety, strong oil pressure makes electric corrode content cannot successful eduction, make discharge condition very flabby decide and cause electric arc to discharge. The means pouring oil that uses commonly is next strong oil, pour oil toward mouth place, drench oil. To oil pressure force control is inside the critical pressure range that approachs treatment, adoption igneous attar should be cleaner. Want in whole treatment process at any time monitoring treatment stabilizes a condition, through seeing scintilla, listen to electric current of sound, observation, volmeter to come assess. Take corresponding step in time to machining medium abnormal phenomenon. B. Surface roughness does not accord with a requirement. Machining finished exterior surface roughness not to accord with a requirement is the common problem with exterior unusual quality. A few nice place ask treatment gives very fine face to use polishing processing again normally, if treatment will increase polishing amount thickly, the influence machines precision of appearance, dimension. Still have a few products are grain of requirement surface scintilla, the exterior surface roughness that this asks treatment comes out accords with a requirement, whole is even. Accurate option of afore-mentioned phone rule is undeserved with element pouring oil also be the main reason that generation surface surface roughness does not accord with a requirement. Still have the effect of the element such as allowance of material of electrode surface surface roughness, electrode, treatment additionally. Electrode surface surface roughness affects the surface roughness that machines the surface directly. It is the surface electrode duplicates when treatment workpiece surface, because the electrode of this finish machining wants polishing processing normally. Electrode material quality is poor, the organization is inhomogenous, the workpiece surface surface roughness that contains the meeting such as foreign matter to make treatment comes out is inhomogenous, short of books a requirement, when choosing electrode material, should be versed in according to adding the requirement of place is reasonable choose. The treatment allowance of rough machining is very big to the influence of finish machining effect. If stay too little, meeting generation finish machining is repaired not only phenomenon. General rough machining stays for finish machining 0.

15mm undertakes Xiu Guang. Big electrode can stay less appropriately than small electrode a few. A few same model when many amount machine antrum should change in time electrode, after machining many place because of electrode, its surface quality can become poor, make the workpiece surface surface roughness of treatment different. C. Heavy panel of exterior metamorphism layer. The high pressure of instantaneous high temperature of the generation when discharge, and working fluid cools quickly action, the degenerative layer with the generation after making workpiece surface ends in discharge and different performance of raw material work. Usually, exterior metamorphism layer is adverse to machining the influence of the result. Especially heavy panel of exterior metamorphism layer, can make treatment surface wearability, fatigue resistance is reduced greatly, produce adverse effect to work service life. The circumstance of degenerative layer heavy panel produces the surface in treatment place to compare little place commonly, because these increase industry position,discharge energy is very big. The position that gives like treatment has the word of small convex, also cannot use big electricity in rough machining, the hot influence of energy of too big discharge can affect the exterior quality of workpiece. (3) processes positional error. After treatment is finished, discover electrode is hit slanting is the common problem with unusual treatment. The means of the workpiece that hold clip, electrode wants firm, won't machining medium happening to become loose. Assure the corrective precision of good electrode and workpiece. Should choose when fixed position accurate fiducial, exact fixed position pattern will undertake. Ensure fixed position is standard without burr, without sundry. Want to control fixed position precision meticulously in unit process of cargo bandling. Should observe treatment place carefully to have in the begining in treatment without deviation, want to check treatment position position in time to have in treatment indiscriminate. Attentive had done these points to be able to prevent to process positional error the happening of unusual appearance. (In 4) treatment unusual. The unusual appearance in electric spark treatment makes whole treatment process cannot on the rails, the unusual problem that appears in treatment middling commonly has: A. Treatment efficiency is very low. The efficiency that electric spark machines affects a mould to machine efficiency directly, should proper control. Electric parameter is the main reason that affects treatment rate. The volume that processes electric current is the condition with the most apparent effect in electric parameter. It is commonly in rough machining, should be in make sure for finish machining obligate the in principle of proper surplus chooses the biggest electric current, rose to machine efficiency already so, also more of facilitating finish machining undertake. If be in rough machining,electric current has been chosen small, affected the efficiency of rough machining above all, the surplus because of finish machining is more at the same time, also reduced the efficiency of finish machining. Raise pulse frequency to increase pulse breadth namely, reducing pulse gap also is the method that improves treatment efficiency. Other assists electric parameter same very important also, if can grow discharge time, decrease carry knife frequency. But should be premise in order to machine stability, machine division job fluid otherwise cannot seasonable disappear ionization, electric corrode child cannot seasonable eduction, bring about those who machine efficiency to drop instead. Should set discharge time length when large area finish machining for instance for very short, carry frequently knife. Only such ability assure the success of treatment, in discharge stable circumstance falls, rose to machine efficiency essentially. The quality of working fluid, the effect of means pouring oil is apparent also. Should choose high grade electric spark to machine fluid, logical way pouring oil is used to make sure a bits is successful when strong oil, the proposal when big electrode is machined is oiled treatment. Treatment place should have prior operation first, leave proper surplus. Mental allowance spends handling time of much meeting grow in quantity and reduce treatment efficiency greatly. Rough machining shoulds not be too much for the deepness surplus of finish machining obligate, below the circumstance that accumulates in bedding face especially, because the electric corrode capacity of finish machining regulation is very small, can increase treatment difficulty when surplus is overmuch and affect treatment efficiency. B. Electrode loss is very big. Can serious effect machines the profile modeling precision of place, dimension precision when electrode loss is too big. Should analyse correctly cause the reason with electrode very big loss. Electric rule allows midrib to develop width is the main parameter that controls electrode loss, be worth in the pulse width that electrode loss should consider to choose below big case whether too small. The electrode material that asks to should consider to choose below very high case in precision whether achieve small loss to machine a requirement. Check treatment losing polarity to whether be received instead. Whether to because machine electric current,cause loss greatly too when small electrode is machined too big. Develop oil pressure power, velocity of flow also can cause electrode greatly too local loss is too big, answer to be adjusted appropriately. C. Discharge condition is not stable. Discharge condition does not stabilize this kind of situation is the unusual appearance that can discover in machining a process, should seasonable processing, lest cause the consequence of influence treatment quality. The meeting when discharge condition is not stable has a series of corresponding show, if scintilla color is red bright, risk Bai Yan, voice is small and frowsty, discharge is centered at one place, needle of electric current, volmeter watch is inhomogenous quickness swings, index of servo dial gauge swings back and forth etc. When discovering these circumstances, answer to consider the impact of electric parameter first, if whether discharge time grows too, cuttings pick-up height is insufficient, whether does width of electric current, pulse pass big, whether does pulse clearance pass small etc. Should consider to machine place to whether be put in sundry, burr next. Should consider those who develop oil pressure force and way to choose again reasonable. D. Electrode happening is out of shape. Electrode happening is out of shape in seeing the treatment at thin small electrode more. This kind is out of shape basically is heat is out of shape. It is servo pressure next too big. To the treatment of this kind of electrode, discharge energy cannot too big, the time that the quantity of heat in machining a process lasts cannot too long. Reason electric current cannot be chosen too big, discharge time wants short, strong oil wants sufficient. When designing electrode, divide structural itself thin outside little place, other machines the electrode of place to should have enough strength. E.

Model arise in aperture treatment " blowout " . Processing the gas of the generation in the process, assemble is in electrode lower end or grease cup interior, get when gas when electric spark ignition, can resemble " blowout " break through obstruction euqally and eduction, make very easily at this moment electrode and sunken model amlposition, this kind of circumstance happens more easily when the treatment that pump oil. Accordingly, undertake in use grease cup model when aperture is machined, want special attention exhaust, carry appropriately the knife perhaps is all round grease cup coping vent one's anger groove, steam vent, with the gas with benefit accumulative eduction. (The causes not carefully treatment with factitious 5) is unusual. Do not take care as a result of what the person is and bring about treatment quality can happen when unusual aborning. These phenomena basically happen in electric spark operator to go up personally, if set coordinate number the mistake, deepness sets a fault, electrode outfit places directional lane to turn over, take wrong electrode, misread blueprint, numerical control program makes up a fault to wait, still the design makes mistake to number etc, these problems are not to make be in technical on, however the most elementary mistake. But sometimes the consequence that a few small errors cause is very serious however. Should avoid to make a mistake as far as possible, raise the technical level of oneself ceaselessly. 3 last words prevent the happening of unusual problem in electric spark treatment to having important sense to improving mould quality. The each link to machining quality influence in treatment of should proper analysis, had held each link, pay attention to each treatment detail, assure final treatment quality. CNC Milling