Much blade lathe tool improves the mechanism analysis that machines exterior quality

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1 foreword is in turning treatment, treatment surface quality is reduced as the addition of cutting deepness normally, accordingly, to obtain treatment exterior quality asks, often must reduce cutting deepness, use turning for many times to excise mental allowance. The application of much blade lathe tool can alleviate effectively the contradiction between treatment surface quality and treatment efficiency. Graph the structure of lathe tool of much blade of principle of treatment of lathe tool of 1 two blade is equivalent to combining lathe tool of many Chan Ren together. It is with two blade lathe tool exemple, if the graph is shown 1 times,its machine a principle. The cutting deepness that sets blade of the first cutting is Ap1, the cutting deepness of blade of the 2nd cutting is Ap2, its are the biggest cutting deepness is the sum of deepness of cutting of each cutting blade, namely Ap ＝ Ap1+ap2. When cutting deepness is less than Ap2, blade of the first cutting is impending, only blade of the 2nd cutting works. Basis " first thick hind essence of life " machine a principle, the cutting deepness of each cutting blade should ordinal and degressive, namely Ap1 ＞ Ap2. Compare with photograph of common lathe tool, much blade lathe tool is satisfying same appearance quality to ask to cutting depth increases below the condition, improve treatment efficiency. In the meantime, when mental allowance is certain, use much blade lathe tool to be able to increase treatment accuracy class, reduce stress of treatment surface remains, reduce lathe flutter, improve workpiece surface quality. The treatment that much blade lathe tool applies to workpiece of smooth axis, via, cylinder to wait, but proper broaden needs to retreat knife chamfer when be being used at processing rod of a flight of stairs, have certain restriction to using range. Existence surface surface roughness, wave spends the mechanism machining surface that improvement of lathe tool of 2 much blade machines exterior quality the physics that waits for layer of surface of sum of errors of exterior geometry appearance, mechanical performance varies. In turning treatment, the factor that affects workpiece surface quality basically has the face surface roughness, cold make stress of remains of sclerotic, surface, surface wave spend etc. Use much blade lathe tool to be able to improve workpiece surface quality effectively. Exterior surface roughness uses much blade lathe tool to be able to reduce the cutting deepness of each cutting blade, the plasticity that reduces cutting force and workpiece material thereby is out of shape, because this can obtain lesser exterior surface roughness. Additional, because cut is smaller, the cold welding action of cutting blade and metallic stuff is lesser, can reduce what the tumour that accumulate bits, scale pricks to generate. Accordingly, use much blade lathe tool to be able to raise workpiece surface surface roughness significantly. Cold in making sclerosis be machined in cutting, the plasticity of metallic surface layer is out of shape make the generation between crystal cuts twist of slippage, crystal lattice intercurrent unripe grain spins, broken reach fiber to change, what cause metallic stuff thereby is cold make sclerosis. Cold make sclerosis can make hardness of workpiece surface layer and intensity rise, tenacity is reduced, become hard fragile, the influence machines exterior quality. Because use much blade lathe tool to be able to reduce material plasticity to be out of shape, because this can be reduced cold make sclerotic pitch. In addition, because apart of many cutting blade is closer, heat in metal cutting sends out harder, can make edge and temperature of area of contact of workpiece surface layer elevatory, the part is quits cold make sclerotic action. Exterior remains stress pursues 2 plasticity are out of shape the leftover stress of generation is in cutting treatment, when relative to base material happening when surface layer material appearance and bulk change, in treatment exterior layer will produce leftover stress, its size follows deepness and change, outer stress and surface layer the stress way of boundary of one base material is opposite, mutual balance. Graph 2a, 2b expresses respectively be out of shape by cold plasticity and thermoplastic be out of shape the leftover stress that cause. When treatment, below cutting strength effect, treatment surface layer pulls stress because of sufferring and already produced stretchy plasticity to be out of shape, watch area incline to increases, already machined exterior layer to be in flexibility to be out of shape right now condition. After cutting force purify, the layer in workpiece is restorable, but outer suffer plasticity to be out of shape the influence cannot be completely restorable, produce remains to press stress in surface layer consequently, the layer arises to pull stress to be balanced to it accordingly in, this is cold plasticity is out of shape the leftover stress that cause. Thermoplastic be out of shape the mechanism that causes leftover stress: When treatment, workpiece surface layer produces heat to expand below action of heat in metal cutting, base material suffers li of layer temperature influence is minor, make surface layer heat expands to be restricted and arise press stress. Exceed material flexibility to be out of shape when cutting temperature after limits, surface layer will produce heat build-up plasticity to be out of shape. After cutting machines an end, temperature drops, material expands restore, but surface layer cannot restore completely because of producing heat build-up plasticity to be out of shape, because this produced remains to pull stress in area of surface layer plasticity, what balance to it arise to press stress in base material. The cold plasticity in cutting process is out of shape with thermoplastic be out of shape the leftover stress way of generation is opposite, can offset each other one part. But because cutting treatment is medium cold plasticity is out of shape bigger, thermoplastic be out of shape lesser, so exterior remains stress is behaved on the whole to press stress. When using much blade lathe tool to machine, because heat in metal cutting sends out not easily, cutting temperature is higher, what arise accordingly is thermoplastic be out of shape reach the remains that cause to pull stress SF opposite also bigger, offset each other through be out of shape with cold plasticity the remains that cause presses stress SB, can reduce damage of S of stress of workpiece surface remains finally, computational method is type of S incomplete =sF-sB=aEDt-sB in: A -- E of linear coefficient of expansion -- stretch model measures Dt -- temperature rise shows material 3 times to succumb by the graph intensity curve is knowable, TB/sub> is taller, criterion SB is smaller, SF is bigger, reason S incomplete increases along with temperature rise faster. Graph the relation surface wave of 3 temperature and leftover stress spends workpiece surface wave basically cause by the flutter that processes a system. When lathe radial cuts treatment, if cutting process is disturbed by an instantaneous, make workpiece and cutting tool produce opposite vibration, can leave a paragraph of ripple in workpiece surface; Falling to turn when cutting, cutting tool is taking moire surface cutting, the change of cutting ply can cause cutting force to fluctuate, this kind of treatment that uses next causing in dynamic cutting master piece is stimulated brace up call second birth flutter. The cutting tool that the graph shows 4 times and workpiece are Ya and Yb respectively relative to oscillatory displacement, its equation is {Ya= | Y | Cos(wt+y) Yb= | Y | The heft that Coswt cutting ply changes along with time is U(t)=Ya-Yb= | Y | [Coswt(cosy-1)-sinwtsiny] =- | Y | 2sin(y/2)[sinwtcos(y/2)+coswtsin(y/2)] =2 | Y | Sin(y/2)cos[wt+(p/2+y/2)] pursues because the relatively oscillatory displacement of 4 cutting tool and workpiece is much blade lathe tool of every cutting blade first phasic and different (it is Y1, Y2 respectively, ... ) , the heft U(t) that changes along with time because of this cutting ply also each are not identical, namely the cutting ply that every engrave each cutting blade temporarily is different, destroyed the second birth flutter that processes a system so, reduce treatment surface wave to spend thereby. Because much blade lathe tool has many cutting blade, treatment surface surface roughness and exterior remains stress can be reduced in turning treatment, the part eliminates workpiece appearance cold the second birth flutter that makes sclerosis and treatment system, can rise effectively to be machined thereby the exterior quality of workpiece. CNC Milling CNC Machining