Tài liệu Helical Gear – using Surface Features Pro/ENGINEER pdf

1 ME-430 INTRODUCTION TO COMPUTER AIDED DESIGN Helical Gear – using Surface Features Pro/ENGINEER 2001 Dr. Herli Surjanhata Create a one side solid protrusion for base feature of helical involute gear as shown below: Create gear parameters by Set Up -> Parameters -> Part -> Create -> Integer Enter diametral_pitch P Enter a value of 8 Continue to create the following parameters: Parameter Type Value Description N Integer 39 No of teeth AGMA_quality Integer 10 tooth_form String 20 DEG INV 2 – AGMA Full-Depth PA Real Number 20.0 pressure_angle Create relations for the gear parameters. From Part menu, select Relations -> Add Enter the following: DP = N/P or pitch_dia_gear = no_gear_teeth/diametral_pitch Hit Enter key twice. Select Edit Rel and enter the following relations with a text editor. A = 1/P addendum = 1/diametral_pitch B = 1.25/P dedendum = 1.25/diametral_pitch DA = DP + 2 * A outside_dia_gear = pitch_dia_gear + 2*addendum DD = DP – 2 * B root_dia_gear = pitch_dia_gear - 2*dedendum DB = DP * COS(PA) Base_gear_dia = pitch_dia_gear * cos (pressure_angle) CP = PI/P circular_pitch = pi/diametral_pitch FW = 3 * CP Face_width Save the file and exit the editor. Select Show Rel to view parameters and verify the relations. Close the information window. Select Relations and pick the protrusion. Note the diametral dimension e.g. ∅ d0. 3 Select Edit Rel and add the following relations: d0 = DA d1 = FW theta_4 = 360/(2*N) theta_1 = 360/(4*N) phi_p = sqrt((DP/DB)^2-1) theta_2 = 180/pi*phi_p - atan(phi_p) theta_3 = theta_4 - theta_1 - theta_2 alpha = theta_2 + theta_1 Save the file and exit the editor. Done -> Regenerate Rename the coordinate system, Set Up -> Name, pick the coordinate system and enter the new name involute_csys Create a datum curve for the involute tooth profile. Select the Create Datum Curve icon. From Equation -> Done Pick the INVOLUTE_CSYS -> Cylindrical. 4 The text editor appears, and enter the following equations: phi=t*sqrt((DA/DB)^2-1) r=0.5*db*sqrt(1+phi^2) theta=(180/pi*phi-atan(phi))-alpha z=0 File -> Exit -> Yes Preview the curve and select OK. INVOLUTE CURVE 5 Create a second datum curve for the root of the tooth. Select the Create Datum Curve icon. Sketch -> Done Pick datum FRONT for the sketching plane and datum TOP for the TOP reference. In addition to the default references, carefully pick the inside endpoint of the involute datum curve. Sketch a center line through the INVOLUTE_CSYS and create an angular dimension from datum TOP. Sketch a second centerline through the INVOLUTE_CSYS that is also aligned to the inside end point of the involute datum curve. Use the Arc, Center and Ends icon to sketch an arc with the center aligned to the coordinate system, and the ends aligned with the centerlines. The arc should lie inside the datum curve. – see Figure below. Create a diametral dimension for the arc. Second centerline First centerline 6 Use the Line icon to create a line from the inside point of the involute datum curve to the arc. From Sketch pull-down menu, select Relation. Sketch this line! 7 Select Add. Enter the following relations: sd1 = theta_4 sd3 = DD Pick the , and then click the OK button. Mirror the involute profile consisted of 2 datum curves previously created. Feature -> Copy Mirror -> Select -> Dependent -> Done Select the two datum curves from the model tree. Done Sel -> Done Make Datum -> Through Select the datum axis A_1 from the model. Through -> Point/Vertex – make sure Point/Vertex is highlighted, and the rest (e.g. AxisEdgeCurv, Plane, Cylinder) is unchecked. 8 Pick the lowest point as shown on the left. Done The resulted curve is shown on the left. Add helix angle as a new parameter. Setup -> Parameters -> Part -> Create -> Real Number -> beta (for helix angle) -> 20 -> -> Done. Create a sweep trajectory datum curve Select the Create Datum Curve icon. 9 From Equation -> Done Pick the INVOLUTE_CSYS Cylindrical Type the following equations in the editor. File -> Exit -> Yes Preview the curve and select OK. Create a normal trajectory datum curve Select the Create Datum Curve icon. Sketch -> Done Pick the RIGHT datum plane as sketching plane. Okay Top -> Pick the TOP datum plane Pick the right face of the cylinder as an additional reference. 10 Sketch a straight line on the datum axis. Pick the , and then click the OK button. Create a new variable section sweep surface. Select From Insert pull-down menu, select Surface -> Variable Section Sweep Norm To Traj -> Select Traj Pick the sweep trajectory as the origin trajectory. Done Sel -> Done Use Norm Traj -> Done Select Traj – Pick the normal trajectory curve. Done Sel -> Done -> Done Open Ends -> Done Sketch this horizontal line. [...]... Loop, and pick each of the three curve segments needed for surface From Sketch pull-down menu, select References 11 Select all the references in the reference window Delete -> Close Pick the , and then click the OK button Copy the cutting surface From Insert pull-down menu, select Surface Operation -> Transform Move -> Copy -> Done Pick the surface just previously created Done Sel Rotate -> CSys Pick... CSys Pick the INVOLUTE_CSYS Z axis Okay Type in: 360/N Done Move 12 Insert -> Cut -> Use Quilt Query select the transformed surface -> Group the cutting surface and cut Feature -> Group -> Cancel the Open window Local Group Type in: cut Select the last two features (transformed surface and cut from the model tree) Done Sel -> Done Pattern -> Pick the Group CUT from the Model Tree Click on dimension... 45° x d with d = 0.05 at the both sides of the hole Create a cut for the keyway with the dimension as shown on the left Hide the datum curves and surface Select the curves and surface in the model tree, right click mouse button, and select Hide 14 The resulted gear is shown below: 15 . DESIGN Helical Gear – using Surface Features Pro/ENGINEER 2001 Dr. Herli Surjanhata Create a one side solid protrusion for base feature of helical. outside_dia _gear = pitch_dia _gear + 2*addendum DD = DP – 2 * B root_dia _gear = pitch_dia _gear - 2*dedendum DB = DP * COS(PA) Base _gear_ dia = pitch_dia_gear