The control of mould finish machining is analysed

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1. Foreword  a mould is become by numerous spare parts matched stack, the quality of the spare parts is affecting the quality of the mould directly, and the final quality of the spare parts is come to those who assure finish by finish machining, because this says count for much of control good precision work.  creates a company in the mould of domestic great majority, the method that finish machining phase uses is grinding commonly, electric treatment and benchwork are handled. Want to control good part to be out of shape in this phase, internal stress, appearance public errand reachs a lot of technology parameter such as dimension precision, in specific manufacturing practice, operation difficulty is more, but the experience method that still has a lot of effective is worth to draw lessons from.  2. The process of mould finish machining controls the treatment of  mould spare parts, a total guiding ideology is in the light of what differ material pledges, different figure, different technique asks to undertake adaptability is machined, it has certain plasticity, can pass the control to treatment, achieve good treatment result.  differs according to the exterior appearance of the spare parts, can distribute the part roughly kind: Axis kind, board kind with abnormity spare parts, its collective process is roughly: Rough machining -- heat treatment (quench, shift is simple) -- essence of life is ground -- report is machined -- benchwork (finishing) -- matched stack treatment.  2.

Heat treatment of 1 spare parts the heat treatment working procedure of  spare parts, in the hardness that makes the spare parts wins a demand while, still need to undertake controlling to internal stress, assure the stability of the dimension when the spare parts is machined, different capable person has different processing kind respectively character. As in recent years the development of mould industry, use material sort grow in quantity, besides Cr12, 40Cr, Cr12MoV, hard alloy, big to intensity of a few jobs, get the protruding with slashing force, sunken model, can choose alloy steel of new material powder, wait like V10, ASP23, this kind of material has taller thermal stability and good constituent state character.  is aimed at the spare parts that pledges for material with Cr12MoV, undertake quenching handling after rough machining, presence of the workpiece after quenching is very large put take stress, bring about the craze in finish machining or job easily, hot temper should be taken the advantage of after the spare parts quenchs, eliminate quench stress. Quench temperature control is in 900 ℃ - 1020 ℃ , cool next to 200 ℃ - 220 ℃ give furnace air cold, subsequently rapid melt down 220 ℃ temper, this kind of method calls sclerotic technology, can obtain higher intensity and wearability, better to giving priority to the mould result that wants invalidation form in order to wear away. A few corner are encountered in production the workpiece with more, complex form, temper still can't be eliminated quench stress, still need to undertake going before finish machining stress anneal or for many times ageing treatment, release stress adequately.  is aimed at the spare parts of pulverous alloy steel such as V10, APS23, can bear because of its high temperature temper, sclerotic technology can be used 2 times when quenching, 1050 ℃ - 1080 ℃ quench, reoccupy 490 ℃ - temper of 520 ℃ high temperature undertakes for many times, can gain taller concussion tenacity and stability, very applicable to giving priority to the mould that wants invalidation form with collapse blade. The cost of pulverous alloy steel is higher, but its performance is good, forming a kind to use a trend extensively. 2.

The grinding of 2 spare partses machines  grinding to machine adoption machine tool to have 3 kinds of main kinds: Round grinder of planar grinder, inside and outside and tool are ground. Want to control grinding strictly to be out of shape when finish machining grinding the generation with grinding crackle, even if very tiny flaw, in follow-up treatment in using, also can show come out. Accordingly, the feed that essence of life grinds wants small, cannot big, cooling fluid wants sufficient, dimension public errand is in 0.

The spare parts of 01mm less than wants as far as possible constant temperature grinding. By computation knowable, the steel with long 300mm, difference in temperature when 3 ℃ , material has 10.

The change that 8 μ M controls, 10.


3 × of 2 × deflection of 3(every 100mm 1.

) of ℃ of 2 μ M/ , working procedure of each finish machining needs mature the influence of this one element. The grinding emery wheel with the very appropriate choice when  essence is ground is very important, the state of tall vanadium tall molybdenum that is aimed at mould rolled steel, choose emery wheel of corundum of GD single crystal more applicable, should machine hard alloy, when quenching the talent with high hardness pledges, preferential the diamond emery wheel that uses organic binder, organic binder emery wheel is good from the sex that grind profit, grind the work that give coarse can amount to Ra=0.

2 μ M, in recent years, as the application of new material, CBN emery wheel, also namely cubic nitrogen changes boracic emery wheel to show very good treatment result, shape in numerical control grind, coordinate grinder, the finish machining on the cylindrical grinder inside CNC, emery wheel of sort of effect excel other. In grinding treatment, want to notice seasonable nap emery wheel, those who hold emery wheel is keen, after emery wheel passivation, can slip in workpiece surface brush, extruding, cause workpiece surface burn, intensity is reduced.  board kind the treatment of the spare parts uses planar grinder treatment for the most part, in treatment regular meeting encounters a kind to grow and small laminose part, the treatment of this kind of spare parts is more difficult. Because add man-hour, below the sorption of magnetic force, workpiece produces deformation, clingy at workbench surface, after taking next work, workpiece can produce a reply to be out of shape again, ply is measured consistent, but requirement of parallelism short of, settlement way can use the filing that lie between magnetism, when grinding in order to wait tall a mat below workpiece, all sides link stopper is touched dead, add man-hour small feed, much smoother knife, after machining good one side, but need not fill up again etc tall piece, attract additional work directly, effect of so ameliorable grinding, achieve parallelism requirement. Axis kind the spare parts has circumgyrate side, its treatment uses round grinder of inside and outside and tool grinding machine extensively. In machining a process, head wearing and tip are equivalent to bus, if its are put in jumpy problem, the workpiece that treatment comes out can produce this problem likewise, affect the quality of the spare parts, because this is before treatment,should do good head to wear those who reach a center to detect the job. Undertake inside when aperture grinding, cooling fluid should irrigate grinding adequately to contact the position, with benefit the successful eduction at grinding. Process thin wall rod kind spare parts, had better use clip to run craft station, clamping force cannot pass big, be in easily otherwise workpiece is circumferential on generation " inside trigonometry " be out of shape. 2.

3 report treatment controls the mould plant with modern  , cannot lack electric treatment, electric treatment can is opposite spare parts of of all kinds abnormity, tall hardness undertakes machining, it divides the cut that it is a line and electric spark 2 kinds. Precision of treatment of cut of silk thread of  don't go yet can amount to ± 0.

003mm, surface roughness Ra=0.

2 μ M. Machine in the begining, want to inspect the condition of the machine tool first, examine water go ion is spent, water is warm, filar verticality, each elements such as tension, ensure good treatment position. Line cut treatment is on a whole material purify is machined, it destroyed the stress with original work to balance, cause stress concentration very easily, be in turning point especially, because this is become R < 0.

2(especially pointed horn) when, answer to put forward to improve a proposal to design branch. The method that stress centers is handled in treatment, can apply vector translation principle, surplus 1mm left and right sides stays first before finish machining, prior operation goes out roughly appearance, have heat treatment again next, let machine stress to be released in the go ahead of the rest before finish machining, assure thermal stability. When  machines punch, the option of silk that cuts the position and way wants careful consideration. Clip of workpiece left end is held, ① of course of the choice when treatment compares course ② to be close friends, maintain place link because of the clip of course ① workpiece and material close together, treatment is stable, if use course ② , after the first feed, workpiece becomes the state that hang a wall, get power difference, affect sequel a few times to machine. Course ③ , use stiletto to wear a treatment, the effect is optimal. Cut of high spirit line is machined, normally cut alls over number to be 4 times, can assure spare parts quality. When treatment contains the sunken module of taper, act on fast and efficient footing, the first rough machining straight edge, taper of the 2nd edge is machined, then again finish machining straight edge, can not need to undertake X so paragraph perpendicular to finish machining, by the side of Duan Zhi of finish machining point, already spare time managing cost. Electric spark treatment should make electrode first, electrode has the branch of thick, essence. Finish machining electrode asks appearance accordance is good, had better finish with treatment of machine tool of CNC numerical control. The material of electrode chooses to go up character, red copper electrode basically is used at general steel treatment. Cu-W alloy electrode, integral performance is good, the wastage in machining a process especially compares red copper apparently small, cooperate full amount erode fluid, suit difficult treatment very much material treatment and sectional form are complex a finish machining. Ag-W alloy electrode compares performance of Cu-W alloy electrode more actor, but its price is high, resource is little, use lesser commonly. When the electrode that make, need the gap amount of computational electrode and electrode amount, when undertake bedding face is accumulated or weighing electrode to machine, workpiece and electrode outfit clip want firm, assure to have enough strength, prevent treatment to become loose. When undertaking late chance to extricateoneself from an awkward position is machined, to electrode everywhere because discharge fluid,loss is reached not the electric arc discharge that free causes, should give attention.  2.

4 finishing and surface of spare parts of matched stack  leave the knife mark, place that grinding mark is stress concentration when treatment, it is the fountainhead with patulous crackle, because this is after treatment end, need undertakes exterior aggrandizement to the spare parts, pass benchwork burnish, processing drops treatment hidden trouble. Undertake to the edge of a few arris of workpiece, acute angle, orifice blunt, r is changed. Popularly, the degenerative and sclerotic layer that report machines the surface to be able to produce M of μ of 6 μ M-10 to control, color shows hoar, sclerotic layer fragile and contain rudimental stress, want to eliminate sclerotic layer adequately before use, the method is exterior polish, hit abrasion to drop sclerotic layer.  is in process of grinding treatment, report treatment, workpiece can have certain magnetization, have weak magnetic force, very easy sorption a few dot, before be being assembled accordingly, want to make demagnetization processing to workpiece, wash the face with fat of second acerbity second. In assembling a process, consult first assembly drawing, make uniform each spare parts, list next each spare parts mutual the equipment between is ordinal, list each answer note, begin to assemble a mould next, assemble install guide pillar guide-post bushing first commonly, install mould bases and punch-die next, be opposite again next everywhere clearance, especially punch-die clearance undertakes matched stack is adjusted, assemble the mould should be carried out to detect after finishing, draw up integral circumstance reports. To the problem of discovery, can use converse thinking method, namely from hind working procedure is forward working procedure, arrive from finish machining rough machining, examination of one by one, until find out crucial point, solve a problem.  3. Last word  carries out a proof, good finish machining process is controlled, can reduce spare parts out of tolerance effectively, discard as useless, improve successful rate of the mould and service life effectively. CNC Milling CNC Machining