The cutting tool that machines free curved surface chooses to consider

The rough machining of the curved surface of effective radius computation that 1 flat bottom establishs milling cutter and semifinishing machining all can use flat bottom to establish milling cutter. In effective 5 axes treatment, interference does not happen when to make make the same score De Lixi the knife machines curved surface, often make cutting tool tilts an angle, this dip makes the actual and effective radius that makes the same score De Lixi knife is not equal to milling cutter radius, the effective radius of milling cutter and cutter shaft dip are concerned. Graph 2 circle contact of point of tangency to turn β and α pursue γ of dip of 3 the smallest axes sets Ax of cutter shaft vector to circle cut contact to turn to feed direction F an angle β , still make cutting tool is circled at the same time cut contact deflexion an angle α (say side slants again horny) , if pursue,2 are shown. These two angle can decide the position of cutter shaft completely. Because be machined,the curvature that curved surface is in in differentia is different normally, the cutter shaft that nods each so is azimuthal different also. The cutter shaft vector that makes the same score a bottom to establish milling cutter is rotational after two angle, plane of bottom of its cutting tool is in inside as perpendicular as feed direction normal plane umbriferous for one ellipse, its maths equation expresses as follows: α of X2+y2=1R2(Rcos β Cos) the curvature radius that X of the type on 2 basises can get this ellipse is: α of Cos of ρ =1+(dy)3/2=[1+x2sin2 β ] α of 3/2dxR2-x2d2ysin β Cos [1+x2] √ (if R2-x2)3R2-x2dx2 uses to pass the circular arc of two end points of knife contact and elliptical long axle shaft to participate in below half ellipse of cutting to won't appear approximately precision error. The radius of this circular arc can regard the average and effective radius of cutting tool as Re. The type on basis of α of Cos of R=kR2sin β of α of Re=1+sin2 β Cos2 is knowable, the average and effective radius of cutting tool changes along with the change of β of cutter shaft dip, be in when the obliquitous β of flat bottom knife when 0 ° ～ has a little change inside 15 ° limits, k can produce bigger change, answer in the β when producing cutting to interfere actually as far as possible small (take 3 ° ) for example, can get at this moment bigger (K=9.

The radius of effective cutting tool of 6) . Accordingly, when with smooth De Lixi the knife machines free curved surface, lesser axial dip angle is used below the premise that does not produce cutting interference, can get bigger effective radius. 4.

When area of 2 treatment sunken curved surface, the affirmatory example of cutter shaft dip never produces local interference to consider to decide the smallest axis is obliquitous the analytic result according to above is knowable, trochoid taking a knife is sunken curve. To avoid to interfere and improve cutting condition, must circle the cutter shaft vector that carries milling cutter direction of feed of knife contact edge to rotate an angle γ , in order to acquire quality of better spare parts surface. By the graph 3 knowable, to avert cutting interference, the least inclination should be cutter shaft: In type of Min of γ =arcsin(R) ρ : R -- milling cutter radius, ρ Min -- the least value that machines radius of curvature of way of way of area edge feed, namely: The axial dip that} of ρ Min=min{ρ never produces overall situation to interfere a consideration to decide ultimate cutting tool is OK undertake test and verify through machining software to emulate, inside treatment area, make interference does not happen with part of curved surface other when milling with dip of the smallest axis. In machining a process actually, to assure good cutting case, take cutting tool dip to be: β = γ + γ 0 among them, can take ～ of γ 0=2 ° according to carrying out experience 3 ° . 4.

3 balls head stands the chooses curved surface precision work of diameter of milling cutter cutting tool to often use ball head to establish milling cutter, ball head stands radius of milling cutter cutting tool by curved surface the biggest advocate curvature decision. Those who set curved surface area is the biggest advocate curvature is K1, K2, and K=k1 · K2<0. Set K1>0, k2<0, criterion K1 is corresponding at be being machined of curved surface sunken to, grow to avoid knife step inside cut interference too, answer to decide the radius of cutting tool for the basis with Min{k1} . R<R1=1max{k1} chooses appropriate cutting tool radius according to cutting tool norms next. Graph 4 sunken curved surface machine row spacing 4.

The leftover height of the curved surface of cutting of relation cutting tool of the diameter that 4 balls head stands milling cutter and row spacing is treatment of test and verify the first standard that whether contented precision asks, it not only the geometrical property with curved surface is relevant, and still depend on the type of method span and cutting tool and dimension (show) 4 times like the graph, the computational formula of leftover height is as follows: H= ρ - in RL28R ρ type, h -- leftover height: L -- the row spacing that cutting tool nods in current cutting: ρ -- the law curvature radius that curved surface has feed way in perpendicular Yu Dao: R -- cutting tool radius: By go up type is knowable: (1) is given to curved surface undertakes machining, if precision is affirmatory (namely leftover height H gives) , the cutting tool of large size can take big row spacing, be helpful for what curved surface machines efficiency rising. (Radius of 2) cutting tool must satisfy R<The condition of ρ , otherwise, leftover height H<0, had happened to cut a phenomenon, the curved surface with law curvature so small radius wants to be machined with cutting tool of smaller part diameter. When 5 epilogue are machined to curved surface in use CAD/CAM software, requirement user chooses cutting tool type and cutting tool dimension independently, the computer can avert interference automatically, computation gives cutting tool contrail. Such cutting tool contrail, effectively treatment gives a product, but precision and efficiency are unwarrantable, so, before be machined to free curved surface, be about to do type of good cutting tool and work of choice of cutting tool dimension. CNC Milling CNC Machining