5 freedom spend free curved surface to machine system and its CAM design

Electric spark of numerical control of construction of research horizontal style line cut machine tool, be used at free curved surface face exceed nicety to make. Be based on a robot kinematic theory is built 5 freedom spend system of machine tool coordinate and derivation gives mathematical model. Quantity of displacement of rod of the movement in executive treatment process compensates computation, developed nicety to machine CAM function of the system. Solved the changeover computation problem that orders quantity of each axis displacement from coordinate. Foreword is making a trade, technology of superprecision of nicety of component of free curved surface has special status and important sense, it is one of crucial factors that decide product function. Treatment of cut of electric spark line exceeds technology of accurate non-traditional machining as a kind of nicety, its technology measure has following characteristics that cannot replace: ① can process the electric metal data of any hardness; Won't get in ② treatment process the action of macroscopical force and influence; ③ treatment precision and exterior quality are very high. Although be used extensively at present line cut machine tool can undertake electric spark of traditional four-axle linkage treatment of groovy taper curved surface, even some taper curved surface that also can machine fluctuation abnormity, but right helicoid, spherical wait for abnormity curved surface its are helpless however [1] . To widen the size range of pipe bent of machine tool of cut of electric spark line, author place belongs to a lab own research and development electric spark of a kind of new-style 5 axes linkage that can be used at superprecision of nicety of free curved surface line cut machine tool. The article builds the solution that reachs its key problem to undertake elaborating in the light of what curved surface processes CAM system. Graph of line cut machine tool shows electric spark of numerical control of construction of type of 1 new-style horizontal stroke 1 times for the tradition electric spark of linkage of 5 axes four-axle diagram of system of drive of line cut machine tool. Graph diagram of system of drive of machine tool of 1 traditional WEDM this kind of machine tool, have X, Y besides workbench beyond axis of two numerical control, going up there still is a workbench on filar wearing, installation U, V axis of two numerical control. The motion of axis of U, V makes of electrode silk on end can tilt, thereby cut gives the appearance that has cone angle. When having average cut, the machine tool of this kind of structure can realize very tall treatment precision, but when undertaking curved surface is machined, its are put in such as to machine difficulty however big, precision is low and the issue with the curved surface very narrow range that can machine. To solve afore-mentioned problems, author place belonged to a lab to develop the pattern of new-style horizontal stroke that following graphs show 2 times line cut machines 5 axes electric spark machine tool. Graph this machine tool uses sketch of construction of system of machine tool of WEDM of 2 perverse form the level takes filar system, mechanical drive system also is different from traditional four-axle linkage machine tool. Did not adopt plan of campaign of axis of U, V, designed however swing axial B and C of runner shaft coming back, be installed to be in by treatment workpiece C axis, the roll that uses work, compound movement way that swing and moves, integrate the numerical control system of a development, can undertake cone, spherical wait for a variety of curved surface treatment, in very old rate spread became wide the size range of pipe bent of WEDM machine tool. System of CAM of 2 machine tools pursues the CAM system block diagram of afore-mentioned 3 machine tools that build for this research. Systematic work flow is: Found in Pro/E above all await treatment workpiece model, use its to take tool Pro/toolkit to undertake 2 times developing oneself, found a program to get the exterior figure data of workpiece, this data is three-dimensional (X, y, z) space chooses the form of coordinate. After undertaking necessary surface interferes the processing such as the examination, input CAM system. Use a robot next kinematic manage fall, establish system of machine tool coordinate and derivation is formulary, beg take two asking 5 axes displacement to measure, will final result carries motion to control systematic control to need the relative position between treatment workpiece and electric machinery silk, thereby the curved surface that cut gives place to need. See by afore-mentioned work flow, compare with photograph of system of CAM of machine tool of linkage of two axes, 3 axes, system of CAM of machine tool of 5 axes linkage became much one nods the changeover link that measures to 5 axes displacement from the space, the key that this one link uses system of machine tool CAM to build 5 axes couplet is in [2, 3] . Block diagram of system of graph 3 CAM derivation of model of maths of system of coordinate of machine tool of linkage of 3 5 axes 3.

The derivation of model of maths of machine tool of linkage of 1 5 axes looks from the angle of athletic geometry, can regarding the machine tool is joint robot, to machine tool coordinate the department seeks solution, in the final analysis attributes the problem that kinematic negate solves the robot. It is namely when electrode silk and the relative position relation that process work are foregone, the displacement of each axial joint measures the machine tool that seek solution (include translation displacement and angular displacement) . According to joint robot kinematic manage fall, in the machine tool athletic coordinate is being built on each joint is, be accompanying joint moves, these athletic coordinate departments are opposite coordinate department. Articulatory axes also regards athletic coordinate as an axis of the department normally, on the diagnostic site that coordinate origin selects a on articulatory axes facilitating knowledge to fasten commonly, calculate in order to go to the lavatory [4 | . To the graph 2 show a machine tool to if the graph is shown 4 times,build coordinate system. O0 is a machine tool coordinate was 0 o'clock, it is fixed coordinate department. Go to the lavatory to be calculated later, electrode silk coordinate was being built on electrode silk in the graph is O ω and make direction of its reference axis follows 05 reference axis initiative direction is consistent, department of O ω coordinate also is changeless for opposite machine tool, coordinate of hypothesis O ω fastens origin in the machine tool coordinate fastened the coordinate in O0 at 0 o'clock is {△ X, △ Y, △ Z} . Graph system of coordinate of 4 machine tools pursues from the graph 4 can see, systematic altogether has 7 variable, because D4 and D5 are machine tool constant, what need to seek solution so is mutual 5 displacement are variable: Dl, D2, D3, θ 4 with θ 5, it is axis of displacement of axis of X axis displacement, Y axis displacement, Z, B respectively swing angle of angle and C axis roll. D1, D2 and D3 are mobile variable, θ 4 with θ 5 it is rotational variable [5] . The basis pursues 4 above all according to neat method of second coordinate commutation builds a machine tool the matrix of commutation of connecting rod parameter of each axes, the symbol states O ω coordinate is fastened in O0 coordinate to fasten medium description, the others analogize. type 8 generation of 1 ～ enter relation of following closed circuit among them, θ 4 it is to swing angle, according to the machine tool actual structure, its take value scope is to be in (- 90 ° of 90 ° ～ ) . When Az=0, θ 4 be in ultimate position one 90 ° (Nz<0) or 90 ° (Nz>0) . θ 5 it is rotational angle, θ of Y=cos of existence relation θ 5 with θ X=sin θ 5. So, when θ Y ＞ 0 when, θ 5 be in the first, 4 quadrant; When θ Y<0, θ 5 be in the 2nd, 3 quadrant; When θ Y=0, θ the 5 integer that are equal to 90 ° times. Going up in the derivation of type, the relative position that is hypothesis electrode silk and treatment workpiece is known quantity. So, want to gain final relation, must know above all. Below with spherical for exemple, the method of the specification that seek solution. 3.

The graph seeking solution of 2 spherical treatment shows the spherical model that builds to be in Pro/E 5 times, ball heart dot is O, p is spherical the dot of a treatment that go up. Graph model of 5 spherical CAD is calculated to simplify, the direction of each axes that ball heart coordinate is O can consult coordinate department structure pursues (the O5 coordinate department on graph 4) is built. Hypothesis O5 and O coincide, when treatment P is nodded, the standard that establishs coordinate department in P dot is: X axis direction handles way for electrode silk place, y axis direction is the mobile direction of electrode silk, if take no account of electrode silk radius and discharge clearance, so the plane with XY axis definite place is spherical plane is cut in what P nods, so Z axis points to ball heart O. When the machine tool is machining P to nod, the coordinate on electrode silk fastens O ω to should nod coordinate to fasten P coincide with treatment. The radius that sets a ball is R, p dot sits mediumly in spherical CAD model, y, z) , easy computation goes out will go up type takes the place of (type 10) can be calculated each axes are in a machine tool the displacement quantity when treatment is spherical. Above with spherical it is a method seeking solution that introduced G5, as to other type curved surface, same method can be used to undertake begging solving after building coordinate to fasten. Use this maths model but the changeover of dot of data of three-dimensional face figure that will extract in Pro/E is displacement of the 5 axes in machining a process to measure, solved the crucial problem that builds system of CAM of machine tool of 5 axes linkage. 4 conclusion use line cut processing technique to undertake curved surface treatment has principal port and wide applied perspective, but traditional WEDM machine tool has various limitation in this respect, restricted the precision of its size range of pipe bent and treatment. This research with new-style machine tool of 5 axes linkage is platform, undertake machine tool curved surface machines the design of CAM system, creativity ground introduced robot theory domain of cut of electric spark line, use a robot kinematic theory, build model of machine tool maths, put forward a kind of new-style algorithm, solved the changeover computation problem that orders quantity of each axis displacement from coordinate, built the CAM system of the machine tool in the compose on this foundation, expanded greatly thereby the size range of pipe bent of line cut machine tool. Of new-style structure fetching, can raise the treatment precision of the machine tool greatly, make line cut machine tool can apply at accurate curved surface treatment. CNC Milling