Mechanical Design Technology

Transcription

1 Mechanical Design Technology rof. Tamots Mrakami Assignment #2: Tool ath and NC Code Generation Make a program that generates a tool path for milling a ezier srface sing a ball end mill shos the tool path graphically on a compter display and generates an NC program for the tool path as a text file Offset Srface and Tool ath If the center of a spherical face at the end of a ball end mill is moved along the [x yz] points of a designed srface as they are the manfactred srface is different from the designed srface namely the srface is ct too deeply A designed srface needs to be offset by the radis r of a spherical face of a ball end mill If the center of a ball end mill is moved along the [x yz] points of the offset srface the manfactred srface is the same as the original designed srface Mechanical Design Technology Tool ath and NC Code Generation ne / 9

2 In Assignment #1 e already have mesh points on a ezier srface In this Assignment #2 please calclate an offset point for every mesh point on the ezier srface; Then connect the offset points as a seqence to form a tool path Mechanical Design Technology Tool ath and NC Code Generation ne / 9

3 ne Mechanical Design Technology Tool ath and NC Code Generation 3 / 9 Offset oint of a Srface : a point on a srface : a tangent vector in direction of the srface at : a tangent vector in direction of the srface at : a normal vector of the srface at e : a nit normal vector of the srface at o : an offset point of Vector prodct: v 1 v 2 [x 1 y 1 z 1 ] [x 2 y 2 z 2 ][ y 1 z 2 - z 1 y 2 z 1 x 2 - x 1 z 2 x 1 y 2 - y 1 x 2 ] r z y x z y x z y x o + ] [ e e

4 ne Mechanical Design Technology Tool ath and NC Code Generation 4 / 9 artial Derivative of the ezier Srface [ ] [ ][ ] [ ] [ ] j i

5 NC rogram A program to control NC Nmerical Control machine tools The examples // Remarks belo are presented to help this handot; Yor NC code mst not inclde them %; // rogram start G90; // G90: Absolte command G91: Increment command G92X0.0Y0.0Z50.0; // G92: Absolte preset Set crrent tool position as [0 0 50] S300M03; // S: Spindle speed rpm M03: Spindle on clockise G00Z20.0; // G00: ositioning Rapid feed to the position G01Z10.0F80; // G01: Linear interpolationf: Tool feed speed mm/min // Yor [x yz] seqence begins here X-7.402Y-4.036Z-0.844; // Tool position of the [x yz] seqence X-0.297Y-4.34Z-4.523; X6.762Y-4.709Z-7.214; X13.808Y-5.134Z-9.09; : // Omitted to make the handot short X86.192Y80.135Z-9.09; Work X93.238Y79.71Z-7.214; X Y79.341Z-4.523; X Y79.037Z-0.844; // Yor [x yz] seqence ends here G00Z50.0; X0.0Y0.0; M05; M02; // G00: ositioning Rapid feed to the position // Tool position [x yz] Retrn to the origin // M05: Spindle off // M02: End of program Crrent position Mechanical Design Technology Tool ath and NC Code Generation ne / 9 G92

6 Detailed Reqirement for Assignment #2 ava rogram Implementation Calclate offset points and connect them as a seqence Diameter d of a spherical face at the end of a ball end mill can be specified as a parameter Three display modes can be selectively sitched ezier srface Tool path ezier srface and tool path NC rogram Generation Use diameter d 15mm For x and y the tool path [x yz] seqence shold range a little ider than the ork size 0mm x 75mm0mm y 50mm so that no portion is left nct For z the tool path shold be ithin -20mm z 0mm to avoid too deep heavy ctting The tool path shold start from the point closest to the origin [0 0 0] becase the ball end mill is initially positioned at [0 0 10] in mm Generate an NC program as a text file consisting of The first six lines of the NC program example as they are given Lines describing yor [x yz] seqence The last for lines of the NC program example as they are given Mechanical Design Technology Tool ath and NC Code Generation ne / 9

7 Z 75mm z0 X Y 50mm z mm X Sbmission Deadline: ne 30 rinted copy copies of the to screens 1 tool path 2 ezier srface and tool path Hand this to me in Room #8-222 or send it by inter-department mail Gaknai-bin NC program Send a text file by to mrakami@mech.t.-tokyo.ac.jp; The program can be an text or an attachment file; Either ay be sre to rite yor name and stdent ID nmber. Schedle Change No lectre Q&A is O on ne 30 Assignment #3 and instrction abot an actal machining on ly 7 ill be sent yo by Mechanical Design Technology Tool ath and NC Code Generation ne / 9

8 Implementation Hint pblic class vector3d /* Method to calclate mltiplication of vector V and scalar A */ /* Usage: Vm V.mltiplyA */ pblic vector3d mltiplydoble a doble ne_x ne_y ne_z; ne_x get_x * a; ne_y get_y * a; ne_z get_z * a; retrn ne vector3dne_x ne_y ne_z; pblic class bicbic_bezier_srface private vector3d nit_normalpoint_lattice polygon_net doble doble Mechanical Design Technology Tool ath and NC Code Generation ne / 9

9 Implementation Hint contined private vector3d offset_pointpoint_lattice polygon_net doble doble doble r vector3d p n; p srface_pointpolygon_net ; n nit_normalpolygon_net ; retrn p.add n.mltiply r ; pblic void dra_ctter_pathpoint_lattice polygon_net doble doble doble r doble[][] matrix offset_pointpolygon_net r; pblic void generate_nc_codepoint_lattice polygon_net doble doble doble r offset_pointpolygon_net r; Mechanical Design Technology Tool ath and NC Code Generation ne / 9