Processing technique of Mashan electric spark makes medium application in the mould
- source:TECHEN CNC Machining
Pulse power source 3.
Automatic feed regulating unit 4.
Working fluid 6.
L of workpiece of sketch map of principle of treatment of electric spark of working fluid pump and tool 4 respectively with pulse power source the two output end of 2 joins. Here of 3(of automatic feed regulating unit is hydraulic pressure oil cylinder and piston) make one very little discharge space often maintains between tool and workpiece, add when pulse voltage polar between, be in opposite some space is the least below the condition at that time place or insulation intensity are the weakest place puncture medium, discharge is spent in this local generation fire, instantaneous high temperature makes tool and workpiece surface local and fused, even aerification evaporates and electric corrode drops one fraction metal, form a small indentation severally. After pulse discharge ends, through pulse time interval, after making working fluid restores to be isolated from, voltage of the 2nd pulse is added again polar on, can be in again at that time extremely span leaves opposite the closest or insulation intensity is the weakest place puncture discharge, electric corrode gives a small indentation. Whole treatment surface will be comprised by place of countless small indentation. Per sec. of loop of this kind of discharge repeats number 1000 times to arrive several times, make workpiece surface forms lots and lots of very small indentation, call electric corrode phenomenon. As tool electrode ceaseless feed, the outline dimension of tool electrode by accurate ground " duplicate " go up in workpiece, achieve the goal of processing. Electric spark treatment can process all sorts of data of high melting point, tall hardness, high strenth, tall purity, tall tenacity, and its treatment mechanism and cutting method differ completely, have the following characteristic: 1, the energy density that pulse discharges is high, facilitating treatment uses the work of the special data that common machining method is hard to machine or cannot process and complex form. Do not suffer material hardness effect, do not suffer heat treatment state to affect. 2, pulse discharge duration is extremely short, the quantity of heat of the generation when discharge is conducted diffuse scope is little, incidence of material be heated is small. 3, when treatment, tool electrode and workpiece material are not contacted, both between macroscopical active force is dinky. Tool electrode material does not need to compare workpiece data hard, accordingly, it is easy that tool electrode is made. 4, can reform work structure, simplify treatment craft, improve work service life, reduce worker labor intensity. 2, the quality that the treatment quality of the main factor pattern that affects mould electric spark to machine quality basically includes to machine precision and electric corrode surface. Parameter of the input in machining a process as a result of electric spark, output is much and relatively complex, of the precision holding clip of the production precision that affects a mould to machine the craft element of precision to involve organic bed itself, workpiece, electrode make reach a lot of side such as rake of clearance of loss of the precision that hold clip, electrode, discharge, treatment, affect with clearance of electrode loss, discharge among them bigger. 1, electrode loss is to machining the influence of precision in process of treatment of mould electric spark, pulse discharge can make tool electrode suffers report is corroded and produce loss, understand consequently and grasp electrode loss pattern, adopt a variety of arrange inflict to reduce the loss of tool electrode as far as possible then, can make sure the mould has taller treatment precision. When electric spark is machined, the different position of tool electrode its loss circumstance also is different, the electric field intensity that normally its wait for raised place by the side of pointed horn, arris is high, easy form point discharge, so place of evenness of its loss ratio wants fast, inhomogenous loss brings about those who machine precision to drop necessarily. At the same time the loss of electrode still suffers the heat physics constant of electrode material to affect. The melting point of electrode material, boiling point, specific heat capacity, fused as taller as aerification latent heat, coefficient of thermal conductivity is bigger, its corrosion resistance is better, conduct heat capability is stronger, can reduce the loss of electrode consequently. 2, when discharge clearance machines a mould to machining the influence electric spark of precision, pulse discharge happens to need to hold certain discharge clearance between tool electrode and workpiece, size of the workpiece that makes treatment goes out hole and electrode dimension photograph are compared, clearance of a discharge should differ on edge treatment outline. Discharge clearance basically decides to machine stability, increase time of pulse discharge space to be able to increase treatment stability commonly. And raise peak value electric current to will make productivity rises, but electrode loss will be increased. Degenerative layer deepens the surface, surface roughness can greaten. Want to make discharge clearance keeps stable, indispensible make the electric parameter of pulse power source keeps stable, still should make machine tool precision and stiffness also keep stable in addition, 2 discharge that at the same time child of corrode of special attention report causes are right the influence of discharge clearance. 3, the Ra of affects electric corrode surface parameter of surface roughness assess to treatment surface surface roughness follows pulse to width and voltaic peak value increase and increase. When machining a condition certainly, pulse width and voltaic peak value add congress to make individual pulse energy increases, make the section dimension of electric corrode indentation increases, because this surface surface roughness is main,depend on the size of individual pulse energy. Should reduce exterior surface roughness the value of Ra, must reduce the energy of individual pulse. 4, the exterior change layer that the surface after the electric spark of influence mould classics to mould surface quality machines exterior change layer comprises generation caky layer and hot influence layer. Caky layer is material of workpiece surface layer happen to fuse and fail to cast below the action of instantaneous high temperature that discharges in pulse piece, rapid after pulse discharge ends refrigeration, caky and the metallic layer that reservation comes down, this metal grain is very petty, have stronger fight corrode ability. Hot influence layer is located in between caky layer and workpiece base material, because suffer discharge to nod the high temperature effect that transmits, make material metallographic organization produces change. Machining the electric parameter that chooses as a result of place in the process, the heat treatment state with cooling condition and workpiece former material is different, the hardness change circumstance of metabolic layer is met different. The electric parameter of the ply of exterior change layer and workpiece material and pulse power source is concerned, add along with the accretion of pulse energy thick, caky layer hardness normally taller. Accordingly, the mould surface wearability after electric spark is machined is close friends than common machining. 3, electric spark processing technique uses the rapid development as a result of mould industry mediumly in mould treatment, to satisfy the need of a few special situations, one large quantities of having the mould material of the special function such as high temperature of high strenth, tall hardness, tall tenacity, tall brittleness, ability arises in succession, brought a lot of new difficulty and issue to conventional metallic cutting treatment thereby, with conventional treatment the method satisfies a requirement again hard, at this moment, electric spark processing technique is machined by wide application and mould. Apply as electric spark processing technique at mould industry, to traditional pattern treatment craft produced very big effect, changed a mould to machine technological process. Groovy treatment method is in anneal junior travel milling is machined; Undertake heat treatment, grinding or electric spark are machined next; Manual finally burnish, polish, treatment cycle is very long. Die is out of shape because of quenching constantly or craze and bring about discard as useless. And electric spark processing technique can machine the pattern plate after quenching, avoid heat to be out of shape malady is mixed set spell a structure, simplified already mould structure, can improve mould intensity and life again. Technology of electric spark modified has very big application in mould surface, to improve the quality of mould surface, use discharge of electric spark pulse to produce the working principle of high temperature, with hard alloy (wait like YG8) make electrode material, reach infiltration of hard alloy material to the mould fragile on working surface, form a tall hardness, high strenth, tall wear-resisting, Gao Naiwen, horniness white that does not come off again alloy aggrandizement layer, change exterior physics, chemical property, it is right the mould has the method with very effective finishing. Layer of electric spark aggrandizement is the instant that electrode and workpiece material are discharging new below condition of high temperature high pressure alloy is changed, and formation new alloy layer, not be the besmear Fu with electrode simple stuff and accumulation. The diffusion layer that azotic element has to wait between alloy layer and base metal, as firm as matrix union, extremely impulse withstand. When aggrandizement is handled, because discharge time is very short, the area that discharge selects very small, the hot action of discharge happens in the small zonule of workpiece surface only, and whole workpiece still is in normal temperature condition or warm up inferior, workpiece is in cold conditions, time is short, won't produce anneal or heat to be out of shape. Electric spark modified undertakes in air or liquid medium. It already can action is in the local surface of the spare parts, also can undertake modified to the plane of general geometry appearance or curved surface, for instance cutting tool, mould, mechanical spare parts. Electrode material can choose according to utility freedom, in repair when spare parts of personal tatty machine, can use the material such as carbolic element, red copper, brass to serve as electrode, these material origin are wider, and material wastage is very few also. The modified layer that the control of the adjustment that can pass pair of electric parameter and modified time will come to obtain different ply and exterior surface roughness. Operation method masters easily, do not need the operation staff with technical high order and degree. It can have the effect that achieves hard to many, expensive whole stuff with a few material, the hardness that can improve a product already, wearability reachs the function such as high temperature red rigid, improve the service life of the product significantly, can reduce valuable data greatly again use up, reduce production or maintain cost. The precision expression of mould of nicety of electric spark treatment antrum is in 3 respects such as quality of dimension precision, profile modeling precision, surface. Machine nicety antrum mould. Should analyse its correctly requirement of each place dimension, control the dimension precision of different place neatly. Answer to take the position with those dimension high demands seriously particularly, the important measure public errand in nicety antrum mould can amount to ± (micron of 2 ～ 3) , see the strict sex that its dimension asks. Profile modeling precision asks also tall, model antrum should clear part, edge is clear. Exterior surface roughness is worth even, achieve book exterior essence coarse to spend a worth, value of general requirement Ra is very little, ask lens face is machined even, the ply of degenerative layer wants appearance of place of treatment of scintilla of other dispatches from foreign news agency very small. 4, brief summary nowadays, develop as economic high speed, a series of distinguishing feature that place of technology of electric spark processing has and the tremendous potential that produce benefit field, the main technique field that makes the country such as heart, beautiful, day study eagerly already, of different specifications all sorts of commercializing high speed machine tool also has entered the market, application is made at plane, car and mould wait for an industry. But electric spark processing technique is in mould industry, in machining a process as a result of electric spark, the factor that affects treatment quality is more, in specific treatment Shi Yinggen occupies the treatment of workpiece to ask, the material of electrode and workpiece, the element such as the technology index of treatment comes logical choice machines parameter, experiment through craft and produce practice to master its to change the rule, machine precision in order to raise a pattern, machine productivity and economy. If these asking that the problem is solved proper, believe to be in before long in the future, electric spark processing technique can have wider and wider application in mould industry, also have better and better prospect. CNC Milling CNC Machining