The injury of small way milling cutter when imperceptible milling lead is brass studies

Between 1mm ～ 10mm, we say for small way milling cutter. Small way milling cutter is a kind of small cutting tool, compare with groovy milling photograph, because the stiffness of small way milling cutter is low, the feed of the cutting tool in treatment uses every tooth normally a few micron are smaller even, and the radius of cutting blade blunt circle of small way milling cutter measures level in a few micron normally, because this brings about imperceptible milling,medium every tine feed is equal roughly radius of cutting blade blunt circle, at this moment workpiece material falls in the action of the attrition of cutting blade, extruding or plough, generation plays plasticity acutenessly to be out of shape. Negligible in groovy milling element (radius of cutting blade blunt circle, cutting tool is tiny jumpy, those who cut bits interrupt the flexibility that reachs workpiece material to restore to wait) main to generation of imperceptible milling process effect. A lot of research show when cutting deepness or every age feed is far when be less than radius of cutting blade blunt circle, will produce apparent dimension effect. Accordingly, imperceptible cutting craft will distinguish small cutting tool to be machined at the cutting of traditional cutting tool significantly, present distinct scale effect. Current, domestic and international scholar cuts the research that cuts craft to still be centered on the process capability of machine tool cutting tool imperceptibly to small cutting tool, to cutting tool wear away and the research of damaged mechanism is very few still. The article machines experiment and the analysis to invalidation of small way milling cutter through imperceptible milling, when studying imperceptible milling of small way milling cutter wear away, damaged configuration and its failure mechanism, aim to be small cutting tool optimize design, reasonable choose the attrition in reaching its cutting to wear away control provides experimental basis. 1 experiment part 1.

Milling cutter of small way of crop of coating of Shuang Ren TiAlN is used in milling cutter of 1 small way and treatment workpiece experiment, cutting tool matrix is material of hard alloy of K30 fine grain, its material character and geometrical parameter express place to show as follows.

Cutting tool of TiAlN coating hard alloy is the TiAlN coating stuff that will have tall chemical stability and tall hardness besmear is added in bending strength taller K kind (WC+Co) horniness combines meeting matrix surface, then acquires the cutting cutting tool that has tall wearability and property of cutting of good high temperature. The material of small way milling cutter and geometrical parameter express length of material of base material coating (length of Mm) blade ministry (diameter of Mm) blade ministry (Mm) petiole diameter (round role of Mm) blade ministry (the horn before µm) (° ) hind horn (° ) helix angle (° ) K30TiAlN381.

00.

53.

Lead of 0351230 workpiece material is brass (HPb63-3) , its Poisson is compared for 0.

Quantity of 29; stretch model is 105GPa; Linear expansion coefficient is 20.

Density of 5 × 10-6K; is 8.

5g/cm3, plumbic brass is had admirable but cutting sex, and have taller anti-friction property, agree with make small part, be in medical treatment, electron, car, horological the application in waiting for an industry is wide. 1.

The numerical control of 3 axes linkage that test of treatment of cutting of 2 experiments process develops in proper motion of Harbin Institute of Technology is small undertake on small-sized milling machine. Over all dimension of this machine tool is 300 × 300 × 290mm, the biggest rotate speed is main shaft 160, 0000r/min, the biggest radial is jumpy for 1µm, drive system repeats fixed position precision for 0.

25µm, system of machine tool control was used but controller of motion of process designing much axis (PMAC) , feedback into complete closed circuit by grating feet compose. The treatment parameter of small part is plumbic brass respectively: Main shaft rotate speed is 120, 000r/min, every tine feed is 1µm, milling deepness is 10µm, milling width is 200µm, cutting tool is dangerous extend a quantity to be 10mm, cooling means is air to cool, milling means is suitable mill plane. Use electron microscope of HITACHI S-570 scanning (SEM) observation cutting tool is macroscopical, microcosmic wear away configuration, use TN-5502 can chart analyzer (EDS) analysis cutting tool wears away the elemental composition of area material. 2 results and discuss to wear away with cutting tool after wear away configuration undertakes comparative, the exterior form appearance of the cutting tool before experimenting to undertaking cutting above all undertakes observing an analysis below scanning electron microscope. Can see, cutting tool surface presents a lot of tiny indentation and microcosmic grain content protuberant, on the whole exterior quality is not high. Corresponding at before knife face circle is in can chart analysis, pass can chart analysis is knowable, bases of coating of cutting tool surface is Ti element, it is Al element next, also contain the element such as the Cu of minim, Co, W, Fe at the same time, prove WC and Co are enclothed basically by coating place. 2.

1 coating flakes concentration of the Al in the coating of TiAlN coating cutting tool is higher, when cutting the surface can generate Al2O3 of very thin the condition that be not brilliant, inert diaphragm, use effectively at high temperature circumstance, when imperceptible milling lead is brass, coating can rise to raise cutting tool wearability, reduce felt tatty effect.

In test of treatment of cutting of small way milling cutter, tiAlN coating arises easily to destroy and flake.

In treatment of cutting of small way milling cutter, because cutting tool diameter and cutting dosage are very small, the position that shares cutting actually gives priority to cutting blade and place of point of a knife; Advocate cutting blade especially place of point of a knife gets intense extruding, cut, the action such as attrition and concussion. With groovy coating cutting tool (coating ply is general photograph of 6 × M) compares 5 ～ , as a result of the limitation of appearance of cutting tool geometry, the coating of small cutting tool is very thin (coating ply is 1 ～ 2µm) commonly, wearability is poorer.

In the meantime, point of a knife is in coating intensity to compare other position weakness, because the heat between coating and matrix expands,differ, normally in coating generation heats up internal stress. Accordingly, advocate cutting blade especially the coating that point of a knife is in is destroyed the most easily, expression is what typical cutting tool coating flakes to wear away feature. 2.

When damaged of 2 point of a knife showed small way milling cutter machines plumbic brass, when happening of point of a knife destroys loss effect hind the SEM form appearance of knife face. Visible, knife face wears away after the area is approximate triangle, place of point of a knife has base material of whole cutting tool to fall off, present appearance of typical form of damaged of point of a knife.

Damaged of point of a knife of small way milling cutter is concussion, mechanical exhaustion and hot exhaustion the result of integrated action. In imperceptible milling treatment, the radial and jumpy quantity of small cutting tool is a when not allow to ignore main factor, machine photograph comparing with groovy cutting, jumpy radius and cutting tool radius compare cutting tool radial (R0/r) wants a lot of bigger, to milling cutter of two blade small way, when material of brass of imperceptible milling lead, get stuck as a result of the outfit of cutting tool and small be out of shape the deviation that waits for space of the cutting tool axes that causes and main shaft axis, make blade of a cutting is carried out all or great majority milling works, another cutting blade participates in a few cutting only or basic not cutting workpiece, right now, cutting tool place suffers cutting force to increase significantly; Department of point of a knife supports sophisticated machine and the action that heat up coupling load, the pressure between point of a knife and workpiece is greater, stress centers a phenomenon remarkable, in the meantime, the circulation that cuts as a result of cutting and sky in milling changes, produce mechanical and fatigue effect to general of point of a knife.

Accordingly, cutting tool wears away accelerate, probability of damaged of point of a knife increases apparently.

Additional, below the condition that flakes in coating, attrition of bare place of point of a knife increases, cutting temperature will be elevatory, present periodic change, the thermal stress that produces point of a knife then is destroyed, this also is a when cause damaged of point of a knife main reason. Expression of damaged of point of a knife is phenomenon of small collapse blade, to the surface of workpiece treatment quality produces main effect, be the scale effect in cutting of small cutting tool is main reflect. 2.

3 stick together wear away to differ with groovy cutting, radius of blunt circle of blade of cutting of small cutting tool is affected to cutting tool tatty cannot oversight, when imperceptible milling lead is brass, every tine feed is far be less than radius of cutting blade blunt circle, small cutting tool with bigger deputy before horn undertakes cutting, cutting tool chafes with what workpiece asks, effect of extruding, plough is distinct, point of a knife and workpiece contact area are very small, cutting tool place gets radial cutting power very big, because this workpiece is right generation of point of a knife is very large press stress.

The oxidation layer that because cut the attrition of bits, workpiece and cutting tool and extruding to destroy cutting tool point of a knife,is in and adsorptive film, strong stick together action is formed between the new face that just cut from workpiece interior. Can see, cutting tool hind has thing of lump stick together on knife face, undertake to the A place above its can chart analysis, its result.

Through can chart analysis can see, content of Cu, Zn is highest, confirm stick together content is plumbic brass. Content of plumbic brass stick together is plumbic brass falls in cutting or attrition action in small milling process tiny the phenomenon of alleged cold welding that cuts bits to issue generation to plasticity is out of shape and happen in high temperature and high-pressured action. Felt of brass of the lead in the experiment basically happens in small cutting tool hind knife face.

Be more than the sticky exert oneself between cutting tool and stick together content when stick together content and the affinity with brass lead when. Felt interface will arise very big pull stress, the material on cutting tool can be cut bits is taken away, the stick together of face of the knife after fashioning small cutting tool wears away form appearance. In the meantime, felt of stick together content is near blade of cutting of small cutting tool, changed the geometrical form of small cutting tool, increased the cutting power that attrition obstruction and location of point of a knife get, quickened cutting tool wear away. 2.

4 the horniness such as carbide, nitride and oxide is contained to nod in grinding bead to because airframe of the inevitably existence impurity in workpiece material, material is organized,wear away. In cutting these horniness name a person for a particular job cause mechanical wear to cutting tool, in cutting tool apparently lay off a channel grain, form grind bead to wear away. When workpiece of brass of imperceptible milling lead, fe element is contained in plumbic brass, generate FeC horniness easily to nod.

Compare with common cutting photograph, these horniness nod the every tine feed of grain dimension and cutting tool, dimension of grain of cutting tool matrix is very adjacent, the attrition between hard particle and cutting tool undertakes between grain, cause the desquamation of cutting tool material easily, form nick of the tatty that wear bead.

In surface of left point of a knife existence grinds bead significantly to wear away feature. 2.

5 diffuse the analysis diffuses to whether exist certainly phenomenon, wear away in cutting tool achieve after grinding blunt standard, undertake to cutting tool can chart analysis, if B, C, D3 is in.

Among them of B place and C place can table chart, d place did not wear away, its can table chart agrees basically. Wear away in point of a knife B is in (cutting tool base material is completely bare already) , 100 minutes of content of Co element are 16.

4637 Wt% , with not content of the Co in the matrix of hard alloy small milling cutter of cutting (make an appointment with 20 Wt%) photograph to compare, change is not very remarkable, 100 minutes of content of Cu and Zn element are 0, show element of the Cu of workpiece material, Zn, did not diffuse gall of point of a knife. Although the main shaft rotate speed of micro computer bed is very high, but cutting linear velocity is not tall (make an appointment with 188mm/min) , the temperature rise that produces by heat in metal cutting right now did not reach the temperature that material of plumbic brass workpiece diffuses to cutting tool.

Wear away in point of a knife C is in (cutting tool coating grinds thin) apparently, content of the Co on coating is 0.

0875wt% , with content of the Co on coating of the cutting tool before wearing away (0.

6137wt%) photograph is compared decrease somewhat, explain Co happening diffuse flow is broken, diffuse to cut bits and workpiece material. After cutting tool A of content of knife face stick together is in, the content of Co is 0.

2589wt% , proved Co diffuses to cut bits and work further. The 1 humble that diffuses to be not stable state solid captures mood mensurable, among them D is the diffusion coefficient related to temperature, can express with Ar-rhenius equation (type 2) . C=(DC)txx(1)D=D0e-Q/RT(2)D0 and Q part to diffuse constant is mixed diffuse activation can, depend on corporeal composition and structure; R is gas constant, t is thermodynamic temperature. By type 1 with type 2 knowable, diffuse speed and diffusion coefficient and elemental chroma gradient are relevant, and diffusion coefficient and temperature concern into the index. Cutting tool surface and there is taller chroma difference between the fresh underside that cut bits, long the Co after cutting will diffuse to be reached to workpiece cut bits. To cutting tool, as a result of Co diffuse, because of,the carbide such as WC, TiC is met of Co photograph decrease and reduce stick together intensity, then aggravate cutting tool wears away.

Accordingly, mix from SEM image can look on chart analysis, there is the behavior that diffuses each other really between cutting tool and workpiece, but the be lost amount of element of the Co on cutting tool is very small.

Accordingly, diffuse in what what imperceptible milling lead produces when brass material the phenomenon is not to cause tatty of small cutting tool main reason. Tatty feature oxidizes without discovery in the experiment, the analysis is knowable, because cutting linear velocity is inferior, satisfy generation hard remarkable oxidation wears away needs heat in metal cutting, do not have the temperature that oxidation place requires. Accordingly, can forecast oxidation to wear away in cutting of small cutting tool to cutting tool the impact is not big. 3 conclusion are imperceptible in milling of small way milling cutter wear away present distinct scale effect, the main be no longer in force of cutting tool and wear away the area happens in place of point of a knife. When material of brass of imperceptible milling lead, small cutting tool basically is behaved flake for coating, damaged of point of a knife, stick together wears away and grind bead to wear away wait for scathing mechanism. Small way milling cutter is when material of cutting lead brass, existing to diffuse between cutting tool and workpiece action, but diffuse the phenomenon is not to cause cutting tool tatty main reason. CNC Milling