Of emulation model of physics of process of fictitious CNC Machining build

1 cutting force emulates a model to be in the emulation of cutting force, about the model of cutting force, somebody thinks, the cutting power that cutting tool gets can regard as the function that purify of unit time stuff leads. Build flute to get stuck on cutting tool above all coordinate is, get on edge 3 orthogonality force. In Ft=KtStFr=KrSrFa=KaSa(1) type: St, Sr, St -- the umbriferous area that cuts bits to go up in 3 coordinate plane. Kt, Kr, Ka -- the data that gets from inside metallic cutting and cutting speed parameter. The method that afore-mentioned cutting force emulate passes S.

The research of Jayaram the error of force of cutting of numerical control machine tool to 3 axes above is bigger, accordingly this emulates a method to suit to be emulated at the cutting force of 3 axes and the numerical control machine tool under 3 axes only. The cutting force that Hirohisa is based on axial of cutting tool edge put forward a kind to divide cutting tool into the cutting force of a lot of parts to emulate a model on the foundation of even distributinging hypothesis. The article is used on this foundation finite yuan of law (FEM) builds cutting force model, differentiate blade of cutting tool cutting a certain number of small yuan right among them small yuan do analysis getting power. So by J cutting tool is small yuan tangential force DFtj(θ , z) , θ of radial load DFrj(, z) and θ of axial force DFaj(, z) can reach fundamental cutting strength. DFtj(θ , z)=[Kte+Ktchj(θ , θ of Z)]dz=[Kte+KtcStsin θ J]dzdFrj(, z)=[Kre+Krchj(θ , θ of Z)]dz=[Kre+KrcStsin θ J]dzdFaj(, z)=[Kae+Kachj(θ , the Kte in the type on Z)]dz=[Kae+KacStsin θ J]dz(2) , Kre, Kae, ktc, Krc, Kac represents cutting coefficient, can check all sorts of medium feed speed to reach by cutting. Hj(θ , z)=Stsin θ J is not the ply of cutting workpiece. Dz is the axial length differential of cutting tool. Each cutting tool of St is small yuan feed. Above (2) type can reach through begging Jie Wei to divide equation cutting tool is in the instantaneous cutting force of 3 direction. Cutting tool is passed in the summation getting power of 3 direction all small yuan of summation in force of cutting of instantaneous of direction of X, Y, Z beg piece. 3.

The model workpiece machining error of 2 machining error gets the influence of a lot of elements, this is emulated to machining error brought a lot of difficulty, because want to emulate a machining error accurately, not only should consider the impact of each individual element to machining error and the weight that still must consider each factor integratedly. C.

Anderssson wore away to make relatively detailed research respectively to the emulation model of workpiece precision to cutting tool of fixed position sum of errors, huaizhong Li is out of shape to machine tool heat and vibration made the research of deep person wait to the model of workpiece machining error. The factor that affects machining error still includes on size error of error of precision of machine tool motion, cutting tool and main shaft deflection, slideway to be out of shape, the error that heat of clamping force, cutting tool, spare parts is out of shape and flexibility is out of shape error and treatment method are caused. Be based on afore-mentioned research to press ambiguous theory to undertake integrated judge reachs influence workpiece machines the total error pattern of precision blurring to these individual errors. (In 3) type, x(t) , Y(t) , Z(t) is hour T is workpiece apparently the place that makes a point, wi expresses I the weight when error overlay, ei[x(t) , y(t) , z(t)] expresses I the error is worth in the error of hour T. Type can convey the error function that is time T to affect the independent variable of cutting tool position and attitude again on: (The machining error that 4) can be in some a little bit so in fictitious treatment on the workpiece when the computation with convenient error of person of be in harmony gives time T. The treatment model that will get after the theoretical model of the product and material of semifinished product purify next begs difference to be able to get machining error model. In process of treatment of VNC machine tool, machining error model expresses to machine area with different color by error size, through undertaking checking to its, the reason that can reach its to may arise to the size of machining error undertakes analytic judge, the producibility that is a product is evaluated provide a basis. 3.

The real time copy that the 3 models that cut bits to build a course cut bits to build a course is fictitious CNC Machining and effective treatment really " without seam join " the main link that demonstrates with synchronism cuts bits generate, reel-up, break off and generated appearance gets the influence of a lot of elements, for instance the material workpiece of fluid of the geometrical appearance with cutting tool, cutting, workpiece and cutting tool is mixed the attrition force between cutting tool and stress factory department and broadness of meet an emergency, cut bits generate mechanism and heat to be out of shape wait for an element to concern, this studies the result already was used by a lot of scholars. C.

The studies discovery should cut bits ply of Andersson special hour (the ply that is less than 2µm) to cut bits and cutting force are linear relation, relation is: Because B1i(5) of · of Cr=Fr/[(nz+1) · H1n had proved the linear between FH and H1n concerns, the FH in replacing relation with Cr so gets: In Cr=Cr1+Cr2/H1n(6) type, cr gives priority to cutting force, cr1, cr2 is the coefficient constant of cutting force, h1n cuts bits ply. But this considers to still continueing on one hand thorough. The proposal of CIRP working group in the Keynote Paper 1998 strengthens research further from the following respects. Reach the control of Mao Bian and fragment, research that restrains a method to make farther deep person to cutting and the mechanism that cut bits to form. Strengthen finite yuan of law (FEM) , muddleheaded theory (network of Choas Theory) , artificial nerve (ANN)) , reach genetic algorithm (GA) is cutting bits to build mechanism and the research that in emulating, use. The experiment cutting bits that the standard cuts the structural classification of bits and standard to build the whole world to unite joins several databases. 3.

Of 4 cutting tool wear away and of deflection cutting tool wear away of model cutting tool wear away the effective method that emulating is life of estimation cutting tool, it is OK the cutting with multifarious leave out experiments already when economy is saved again, it also is choice cutting tool and cutting condition continent garment is occupied. The cutting experiment that goes up in CNC Milling according to horniness cementite steel, of cutting tool wear away to already hole shape wears away to again plane wears away. The cutting tool that experimental data makes clear distance of every unit feed and unit area wears away bulk Dw/dl and cutting temperature θ and press stress σ to concern, namely: θ of Dw/dl=c1 σ Texp(-c2/ ) (the feature that the C1 in 7) type, C2 is cutting is invariable, θ is the absolutely temperature of cutting. Of cutting tool be out of shape the model is out of shape in grinding cutting tool in the model, the linear of cutting tool is out of shape and nonlinear be out of shape should consider. Learn a model to assume cutting master piece is used in part of point of a knife to facilitate the analysis uses general solid physical power here. Be out of shape from what measure cutting tool can reach the interface between cutting tool and cutting tool collet accumulates pair of cutting tool be out of shape a very big effect, linear of each bits when point of a knife is Z to cutting tool distance is out of shape can press type is calculated. The Fx in the type on Mx(l-z)(8) of · of Fy+Er of · of Y(z)=Eh of ε of My(l-z) of · of Fx+Er of ε X(z)=Eh · and Fy are tangential force is in X, y to component of force, er and Eh are translation and gyral coefficient constant, can get through the experiment, the moment that the cutting force of Mx and place of My point of a knife produces. What L(9) of · of Fx of ＝ of LMy of · of Mx ＝ Fy grinds cutting tool as a result of end is nonlinear be out of shape can be simplified cantilever bridge model, of axis of Z of cutting tool edge nonlinear be out of shape press type is calculated. δ X(z)=Fx · (L-z)2 · (· of 2l+z)/6EJ δ Y(z)=Fy (L-z)2 · (2l+z)/6EJ(10) so, the total deformation that cutting tool nods in random of edge Z axis can get from inside next type: Y(z)(11)3 of δ of Y(z)+ of ε of X(z)Dy(z)= of δ of Dx(z)= ε X(z)+ .

The treatment process of grinding of model of 5 treatment temperature and turning is successive change, continuously model Huaizhong Li of treatment temperature model has given out namely Tstatic=T[1-v Lg(ε / the temperature that the T in ε 0)](12) type is cutting dot, v is the material parameter constant that give out, ε is rate of meet an emergency, ε 0 it is the rate of critical meet an emergency with material insusceptible character. Milling is intermittent cutting process cannot direct will (the temperature that 12) type cuts treatment with Yu Xi is emulated. In intermittent cutting the warm-up of cutting temperature delivers a process to follow change of cutting time T(t) , to arrive with continuously the smooth position with same cutting, tstatic must consider. Warm-up gives out to deliver the temperature model of the process below: T(t)=Tstaticexp(τ / in T)+Tmin(13) type: τ is constant, t is the cutting time that the each mill in a cycle ages; Tmin and Tp are cutting cycle is medium the smallest with highest temperature. Tmin=Tpexp(-t2/ τ ) Tp=Tstatic · [Exp(- τ / T1)/(1-exp(-t2/ τ ) ) ] (the T1 in 14) type, T2 points to the cutting in a cycle and blame cutting time respectively, because the whirl of cutting tool is periodic,be 60/nR(S) , have T1=(60/nR) · so (· of Øgx-Øst)/2 π T2=(60/nR) [1-(Øgx-Øst)/2 π ] (of the milling cutter when the Øgx in 15) type, Øst points to milling respectively cut horn and leave part. In milling the temperature of cutting area uses formula above all (12) computation lasts cutting temperature, pass next (13) ～ (15) type is amended. 3.

6 oscillatory models are in most model, the vibration that considers power of static cutting power to may be caused only also machines those who affect work exterior precision. Can offer the basis that avoid or reduces vibration to choose to machine a condition reasonably to be being emulated oscillatorily in real time. Already did a large number of works in this field learned man and established main emulation theory. But the problem of existence is to make much more important variable parameter be measured hard and measure precision to also assure hard. It is very important to have two respects data: The kinetic parameter of Lai Yu machine tool, workpiece and cutting tool and the position that follow cutting force vector and the system that direction changes. State of cutting tool appearance and the treatment material related to cutting force, material, cutting, cutting tool wears away the kinetic behavior of the change such as type and wear extent. A 2 freedom spend milling vibration model, assume in this model oscillatory direction is the X with mutual and perpendicular edge and Y direction, and feed direction is edge X axis. Coordinate department is secured to be on NC milling machine, axis and advocate amplitude is right neat, milling cutter has N tine and distributing equably. The oscillatory model of milling cutter system by below differential equation gives out: (The M in 16) type, C, K is milling machine emulation model coefficient of the quality in direction of X, Y, damp and bedspring tigidity coefficient, fxj and Fyj are J the milling force on mill tine is in X, Y to component of force, n is the tine number of milling cutter. 3.

The physics such as the temperature that model of 7 attrition force cuts the attrition force of bits and tool cover to affecting the figure that cuts bits, system emulates a lot of medium elements attrition force enters workpiece to arrive inside the time that leaves work in blade of cutting tool cutting is change, the temperature of the size of cutting attrition force and system, workpiece and the plasticity that cut bits are out of shape etc between have very mutual influence, complex concern, this collects bit more critical data with respect to the requirement, so that,build database of the parameter that cut bits better build attrition force to emulate a model, command attrition force effectively. Equation (17) gave out nonlinear attrition force emulates a model. The attrition force that T of the τ in T/k)(17) type of τ T/k=1-exp(µ σ and &sogma;t are tool cover and pressure, k is the shearing force coefficient that cuts bits, µ is the diagnostic parameter constant of material. Of emulation model of physics of 4 brief summary building is the foundation that physics emulates and key. Had done much work in a lot of respects, also gained certain headway, but the author thinks, existing VNC machines a process to emulate a system to cannot give an user accurate result, very the alternant sex that realizes VM only and be enmeshed feeling, the research of the model still remains to be perfected further. The mensurable computation that emulates a model to make accordingly and effective treatment are same, the author suggests must from the following the research that 4 respects strengthen physics to emulate. Experimental respect: The cutting test that establishs physics to emulate whole process joins several databases. Mechanism respect: Emulation mechanism and effective treatment mechanism and both the farther lotus root between joins a concern. Emulation domain: Emulate the molecular power that reachs imperceptible cutting to emulate a domain to expand to the physics of high speed cutting, hard alloy cutting. Emulation method: The diversification of emulation method and method, be like finite yuan of law (network of FEM) , artificial nerve (ANN) . CNC Milling