Tài liệu Oscillating Cam Mechanism doc

1 ME-430 INTRODUCTION TO COMPUTER AIDED DESIGN Oscillating Cam Mechanism Pro/ENGINEER Wildfire 2.0 Dr. Herli Surjanhata There are 5 parts, one subassembly, and one assembly need to be created: • base.prt — the ground body, comprised of two parts • cam.prt — a rounded, elongated solid with flat faces • roller.prt — a wheel with flat faces with that serves as the second cam • follower.prt — a holder for the roller • pin.prt – a cylindrical pin for attaching roller to the follower • follower.asm—a subassembly connecting roller.prt and follower.prt with a pin • cam_follower.asm—an assembly comprised of a cam and a roller follower joint 2 PART: PIN.PRT Create a part called pin.prt as illustrated in the figure below. PART: CAM.PRT Create a part called cam.prt. Note that the cam part is created by extruding both sides using FRONT datum plane as sketching plane. 3 4 PART: BASE.PRT Create a part called base.prt as shown below. Note that a datum point PNT0 should be inserted a center of the hole of the top portion of base.prt. The location of datum point is in the bottom surface of the top portion of base.prt. 5 6 PART: ROLLER.PRT Create a part named roller.prt 7 PART: FOLLOWER.PRT Create a part called follower.prt Insert a datum point PNT0 at the center of shaft as shown in the figure. 8 CREATE A SUB-ASSEMBLY - follower.asm Create an assembly called follower.asm. The assembly should have default datum planes – ASM_FRONT, ASM_RIGHT, and ASM_TOP. Bring in the part follower.prt, and click to assemble the follower.prt at default location. Bring in pin.prt, and constrain the pin to the follower.prt. • Align the axis of the pin with the axis of hole of the follower. • Align the FRONT datum plane of the pin with the ASM_FRONT datum plane of the follower assembly. 9 Bring in the part roller.prt, and click on Connect tab to create a pin Conection_1 as shown below. • Align the axis of the roller with the axis of the pin as Axis alignment constraint. • Align the FRONT datum plane of the roller with the ASM_FRONT datum plane of the follower assembly as Translation constraint. Save the follower.asm assembly. 10 CREATE AN ASSEMBLY – cam_follower.asm [...]... the Click narrow end of cam. prt When an diamond appears on the model, move the cursor to rotate the cam Notice that the cam' s motion does not affect the position of the follower subassembly Click the middle mouse button to stop dragging, and click Close to exit the Drag dialog box Select Mechanism -> Cams or click The Cam- Follower Connections dialog box opens Click New The Cam- Follower Connection... Done Sel Click OK to accept the definition, and Close to exit the Cam- Follower Connections dialog box Mechanism Design adds a cam- follower icon to your mechanism Select Mechanism -> Drag The Drag dialog box opens Click (Point Drag) and rotate cam. prt Note that the motion of the follower subassembly is now linked to the motion of the cam 18 CREATING A SPRING There is a cylinder joint connecting follower.prt... Align offset the back surface of the cam. prt with the front surface of the bottom portion of base.prt as Translation constraint The offset distance is 17.5 mm Rotate the cam to the position as shown in the figure below 13 14 CREATING A CAM- FOLLOWER CONNECTION, SPRING, AND DAMPER CREATING A CAM- FOLLOWER CONNECTION From Application pull down menu select, Mechanism - Mechanism Design begins 15 (Drag) The... dialog box opens 16 On the Cam1 tab, select the Autoselect check box Mechanism Design completes the selection of a set of surfaces after you select enough surfaces to define a cam in Use the arrow button the Surfaces/Curves area to select the curved surface on cam. prt Note: Use Right-Mouse-Button popup menu Pick From List to pick the needed surfaces Done Sel 17 Select the Cam2 tab Select the Autoselect... plane of the follower.asm with the ASM_FRONT datum plane of the cam_ follower.asm assembly as Rotation constraint Make sure to move the follower assembly so that its position as shown in the figure below 11 12 Bring in the part cam. prt, and click on to create Connect tab a pin Conection_2 as shown below • Align the axis of the shaft of the cam with the axis of the hole of the bottom portion of base.prt... unstretched spring length Clear the Default check box and enter 20 in the Icon Diameter area Click OK to accept the definition, and Close to exit the Springs dialog box Mechanism Design adds a spring icon to your mechanism 19 20 CREATING A DAMPER Click Mechanism -> Dampers or click (Define Dampers) The Dampers dialog box opens Click New The Damper Definition dialog box opens Select Point-to-Point under Reference... C, the damping coefficient, in the Properties area Click OK to accept the definition, and Close to exit the Dampers dialog box Mechanism Design adds a damper icon to your mechanism 21 22 CREATING A SERVO MOTOR On the Model Tree, under CONNECTIONS -> JOINTS, expand JOINT_2 (CAMFOLLOWER) by clicking the plus sign (see figure) Highlight ROTATION AXIS, right-click, and select Servo Motor The Servo Motor... click Add all motors) 26 Click Run The model moves through the specified motion To view the analysis results in later sessions of Mechanism Design, you must save them as a playback file Click OK, then Close the Analyses dialog box CREATING AND GRAPHING MEASURES 27 Click Mechanism > Measures The Measure Results dialog box opens Note that Dynamic Oscillations is listed under Result Set Accept Measure... arrow button to select the spring on your mechanism, and accept Each Time Step as the Evaluation Method Click OK to accept the definition and return to the Measure Results dialog box 30 Click (Create new measure) On the Measure Definition dialog box, enter Damper_Load under Name, and select Net Load under Type Use the arrow button to select the damper on your mechanism, and accept Each Time Step as the... Servo_Load under Name, and select Net Load under Type Use the arrow button to select the servo motor on your mechanism, and accept Each Time Step as the Evaluation Method Click OK to accept the definition and return to the Measure Results dialog box Note: Servo motor is located at pin joint between cam. prt and base.prt 31 32 On the Measure Results dialog box, select Follower Position, Follower Velocity, . Close to exit the Cam- Follower Connections dialog box. Mechanism Design adds a cam- follower icon to your mechanism. Select Mechanism -> Drag dialog box. Select Mechanism -> Cams or click . The Cam- Follower Connections dialog box opens. Click New. The Cam- Follower Connection Definition